维普中文期刊产品整合服务
51篇 您的检索式:作者名="Jiaming Zhou"
    题名 作者 年代 出处 被引量
13D printing of bone tissue engineering scaffolds显示文摘Tissue engineering is promising in realizing successful treatments of human body tissue loss that current methods cannot treat well or achieve satisfactory clinical outcomes.In scaffold-based bone tissue engineering,a high performance scaffold underpins the success of a bone tissue engineering strategy and a major direction in the field is to produce bone tissue engineering scaffolds with desirable shape,structural,physical,chemical and biological features for enhanced biological performance and for regenerating complex bone tissues.Three-dimensional(3D)printing can produce customized scaffolds that are highly desirable for bone tissue engineering.The enormous interest in 3D printing and 3D printed objects by the science,engineering and medical communities has led to various developments of the 3D printing technology and wide investigations of 3D printed products in many industries,including biomedical engineering,over the past decade.It is now possible to create novel bone tissue engineering scaffolds with customized shape,architecture,favorable macro-micro structure,wettability,mechanical strength and cellular responses.This article provides a concise review of recent advances in the R&D of 3D printing of bone tissue engineering scaffolds.It also presents our philosophy and research in the designing and fabrication of bone tissue engineering scaffolds through 3D printing.Chong Wang Wei Huang Yu Zhou Libing He Zhi He Ziling Chen Xiao He Shuo Tian Jiaming Liao Bingheng Lu Yen Wei Min Wang 2020Bioactive Materials2020,5,1:20
2Single-cell transcriptomic atlas of primate cardiopulmonary aging显示文摘Aging is a major risk factor for many diseases,especially in highly prevalent cardiopulmonary comorbidities and infectious diseases including Coronavirus Disease 2019(COVID-19).Resolving cellular and molecular mechanisms associated with aging in higher mammals is therefore urgently needed.Here,we created young and old non-human primate single-nucleus/cell transcriptomic atlases of lung,heart and artery,the top tissues targeted by SARS-CoV-2.Analysis of cell type-specific aging-associated transcriptional changes revealed increased systemic inflammation and compromised virus defense as a hallmark of cardiopulmonary aging.With age,expression of the SARS-CoV-2 receptor angiotensin-converting enzyme 2(ACE2)was increased in the pulmonary alveolar epithelial barrier,cardiomyocytes,and vascular endothelial cells.We found that interleukin 7(IL7)accumulated in aged cardiopulmonary tissues and induced ACE2 expression in human vascular endothelial cells in an NF-κB-dependent manner.Furthermore,treatment with vitamin C blocked IL7-induced ACE2 expression.Altogether,our findings depict the first transcriptomic atlas of the aged primate cardiopulmonary system and provide vital insights into age-linked susceptibility to SARS-CoV-2,suggesting that geroprotective strategies may reduce COVID-19 severity in the elderly.Shuai Ma Shuhui Sun Jiaming Li Yanling Fan Jing Qu Liang Sun Si Wang Yiyuan Zhang Shanshan Yang Zunpeng Liu Zeming Wu Sheng Zhang Qiaoran Wang Aihua Zheng Shuguang Duo Yang Yu Juan Carlos Izpisua Belmonte Piu Chan Qi Zhou Moshi Song Weiqi Zhang Guang-Hui Liu 2021Cell Research2021,31,4:10
3Alendronate loaded graphene oxide functionalized collagen sponge for the dual effects of osteogenesis and anti-osteoclastogenesis in osteoporotic rats显示文摘Graphene Oxide(GO)-related hydrogels have been extensively studied in hard tissue repair,because GO can not only enhance the mechanical properties of polymers but also promote osteogenic differentiation of mesenchymal stem cells.However,simple GO-related hydrogels are not ideal for the repair of osteoporotic bone defects as the overactive osteoclasts in osteoporosis.Alendronate(Aln)is known to inhibit osteoclasts and may bind to GO through covalent connection.Therefore,delivering Aln in GO-related hydrogels may be effective to repair osteoporotic bone defects.Here,we developed a control-released system which is constructed by collagen(Col)-GO sponges loaded with Aln(Col-GO-Aln)for osteoporotic bone defect repair.In vitro,Col-GO-Aln sponges prolonged the release period of Aln,and the sponge containing 0.05%(w/v)GO released Aln faster than sponge with 0.2%GO.Furthermore,tartrate-resistant acid phosphatase(TRAP)and F-actin staining demonstrated that Col-GO-Aln sponges effectively inhibited osteoclastogenesis of monocyte-macrophages.In vivo,micro-CT scan showed that the volume of newborn bone in defect site by 0.05%GO sponge was nearly three times larger than that of other groups.Moreover,the CT and histological examinations of rat femur proved that Col-GO-Aln sponges decreased the number of osteoclasts and suppressed the systemic bone loss in osteoporotic rats.These findings reveal that the application of GO as carriers of anti-osteoporosis drugs is a viable treatment for osteoporosis.The results also underscore the potential of GO-related hydrogels with Aln-releasing capacity for bone regeneration in osteoporosis.Yuyang Zeng Muran Zhou Lifeng Chen Huimin Fang Shaokai Liu Chuchao Zhou Jiaming Sun Zhenxing Wang 2020Bioactive Materials2020,5,4:10
4Incidence and clinical characteristics of inflammatory bowel disease in a developed region of G uangdong P rovince, C hina: A prospective population‐based study显示文摘Zhirong Zeng Zhenhua Zhu Yuyu Yang Weishan Ruan Xiabiao Peng Yuhuan Su Lin Peng Jinquan Chen Quan Yin Chao Zhao Haihua Zhou Shuai Yuan Yuantao Hao Jiaming Qian Siew Chien Ng Minhu Chen Pinjin Hu 2013J Gastroenterol Hepatol2013,,7:5
5Precise temporal regulation of Dux is important for embryo development显示文摘Dear Editor,Zygotic genome activation(ZGA)following fertilization is accomplished through a process termed the maternal-to-zygotic transition,during which the maternal RNAs and proteins are degraded and zygotic genome is transcriptionally activated.In mice,minor ZGA occurs from S phase of the zygote to G1 phase of the two-cell(2C)embryo,while major ZGA takes place during the middle-to-late 2C stage with a burst of transcription of totipotent cleavage stage-specific genes and retrotransposons.Mingyue Guo Yanping Zhang Jianfeng Zhou Yan Bi Junqin Xu Ce Xu Xiaochen Kou Yanhong Zhao Yanhe Li Zhifen Tu Kuisheng Liu Jiaming Lin Peng Yang Shaorong Gao Yixuan Wang 2019Cell Research2019,29,11:5
6Single-nucleus transcriptomic landscape of primate hippocampal aging显示文摘The hippocampus plays a crucial role in learning and memory,and its progressive deterioration with age is functionally linked to a variety of human neurodegenerative diseases.Yet a systematic profiling of the aging effects on various hippocampal cell types in primates is still missing.Here,we reported a variety of new aging-associated phenotypic changes of the primate hippocampus.These include,in particular,increased DNA damage and heterochromatin erosion with time,alongside loss of proteostasis and elevated inflammation.To understand their cellular and molecular causes,we established the first single-nucleus transcriptomic atlas of primate hippocampal aging.Among the 12 identified cell types,neural transiently amplifying progenitor cell(TAPC)and microglia were most affected by aging.In-depth dissection of gene-expression dynamics revealed impaired TAPC division and compromised neuronal function along the neurogenesis trajectory;additionally elevated pro-inflammatory responses in the aged microglia and oligodendrocyte,as well as dysregulated coagulation pathways in the aged endothelial cells may contribute to a hostile microenvironment for neurogenesis.This rich resource for understanding primate hippocampal aging may provide potential diagnostic biomarkers and therapeutic interventions against age-related neurodegenerative diseases.Hui Zhang Jiaming Li Jie Ren Shuhui Sun Shuai Ma Weiqi Zhang Yang Yu Yusheng Cai Kaowen Yan Wei Li Baoyang Hu Piu Chan Guo-Guang Zhao Juan Carlos Izpisua Belmonte Qi Zhou Jing Qu Si Wang Guang-Hui Liu 2021Protein & Cell2021,12,9:5
7Large-Scale Test Model of the Progressive Deformation and Failure of Cracked Soil Slopes显示文摘A large-scale test bed(LWH=6 m×3 m×2.8 m)instrumented with various sensors is used to examine the effects of rainfall infiltration and evaporation on the deformation and failure of cracked soil slopes,taking the Anhui area along the Yangtze River as a field example.The results indicate that(1)during rainfall,the soil around the shallow shrinkage fissures attains transient saturation,and the attendant decrease of matric suction is the primary cause of the shallow slope failure;(2)slope deformation continues during post-rainfall evaporation;(3)if a period of evaporation is followed by heavy rainfall,soil creep is concentrated near the deepest cracks,and two zones of steep gradients in pore pressure form at the crest and toe of the slope.Finally,a saturated zone forms near each crack base and gradually enlarges,eventually forming a continuous saturated layer that induces the slope instability or failure.Zhi Zhou Jiaming Zhang Fulong Ning Yi Luo Lily Chong Kuangbiao Sun 2020Journal of Earth Science2020,31,6:3
8Evaluation of Soil Fertility Suitability of Yiliang Tobacco-growing Areas in Yunnan Province显示文摘Abstract[Objective]This study was conducted to evaluate the soil fertility in Yiliantobacco-growing areas of Hunan Province.[Method]The soil nutrient contents iseven tobacco-growing towns of Yiliang County,Yunnan Province were surveyefrom 2010 to 2013 and integrated soil fertility index(SFI value)was calculated tanalyze the soil fertility suitability in theses areas.[Result]The soil p H,contents oorganic matter,hydrolytic N,rapidly available K and available B were all at an appropriate level,while the contents of rapidly available P,available Mg,available Zand water-soluble Cl-were high.Among them,the contents of available P and water-soluble Cl-had great variation.Finally,the soil fertility suitability of Yiliang tobacco-growing areas was graded based on their SFI values.As a result,20%of thestobacco-growing areas were in Grade I,47.7%in Grade II,29.3%in Grade III1.5%in Grade IV and 1.5%in Grade V.The average SFI was 0.61.From 2010 t2013,the p H value and available Mg content reduced year by year,while the contents of organic matter,hydrolytic N,rapidly available P,rapidly available K,available Zn,available B and water-soluble Cl-were increased.Yujun WANG Jiheng ZHOU Xinlang LU Lijuan CHEN Chao WANG Jiaming YANG 2014Agricultural Science & Technology2014,15,12:2
9Low‐intensity pulsed ultrasound ameliorates angiotensin II-induced cardiac fibrosis by alleviating inflammation via a caveolin-1-dependent pathway显示文摘Objective:Cardiac hypertrophy and fibrosis are major pathological manifestations observed in left ventricular remodeling induced by angiotensin II(AngII).Low-intensity pulsed ultrasound(LIPUS)has been reported to ameliorate cardiac dysfunction and myocardial fibrosis in myocardial infarction(MI)through mechano-transduction and its downstream pathways.In this study,we aimed to investigate whether LIPUS could exert a protective effect by ameliorating AngII-induced cardiac hypertrophy and fibrosis and if so,to further elucidate the underlying molecular mechanisms.Methods:We used AngII to mimic animal and cell culture models of cardiac hypertrophy and fibrosis.LIPUS irradiation was applied in vivo for 20 min every 2 d from one week before mini-pump implantation to four weeks after mini-pump implantation,and in vitro for 20 min on each of two occasions 6 h apart.Cardiac hypertrophy and fibrosis levels were then evaluated by echocardiographic,histopathological,and molecular biological methods.Results:Our results showed that LIPUS could ameliorate left ventricular remodeling in vivo and cardiac fibrosis in vitro by reducing AngII-induced release of inflammatory cytokines,but the protective effects on cardiac hypertrophy were limited in vitro.Given that LIPUS increased the expression of caveolin-1 in response to mechanical stimulation,we inhibited caveolin-1 activity with pyrazolopyrimidine 2(pp2)in vivo and in vitro.LIPUS-induced downregulation of inflammation was reversed and the anti-fibrotic effects of LIPUS were absent.Conclusions:These results indicated that LIPUS could ameliorate AngII-induced cardiac fibrosis by alleviating inflammation via a caveolin-1-dependent pathway,providing new insights for the development of novel therapeutic apparatus in clinical practice.Kun ZHAO Jing ZHANG Tianhua XU Chuanxi YANG LiqingWENG TingtingWU XiaoguangWU Jiaming MIAO Xiasheng GUO Juan TU Dong ZHANG Bin ZHOU Wei SUN Xiangqing KONG 2021Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)2021,22,10:2
10Termination of Transcription of LAT Increases the Amounts of ICP0 mRNA but Does Not Alter the Course of HSV-1 Infection in Latently Infected Murine Ganglia显示文摘On entering sensory ganglia,herpes simplex viruses 1(HSV-1)establishes a latent infection with the synthesis of a latency associated transcript(LAT)or initiates productive infection with expression of a set of immediate early viral proteins.The precise mechanisms how expression of a genes is suppressed during the latency are unknown.One mechanism that has been proposed is illustrated in the case of ICP0,a key immediate early viral regulatory protein.Specifically,the 2 kb LAT intron is complementary to the 30 terminal portion of ICP0 m RNA.To test the hypothesis that accumulation of LAT negatively affects the accumulation of ICP0 m RNA,we inserted a DNA fragment encoding two poly(A)sequences into LAT to early terminate LAT transcript without interrupting the complementary sequence of ICP0 transcript(named as SR1603).Comparisons of the parent(SR1601)and mutant(SR1603)HSV-1 viruses showed the following:Neurons harboring latent SR1603 virus accumulated equivalent amounts of viral DNA but higher amounts of ICP0 m RNA and lower amounts of LAT,when compared to neurons harboring the SR1601 virus.One notable difference between the two viruses is that viral RNA accumulation in explanted ganglia harboring SR1603 virus initiated significantly sooner than that in neurons harboring SR1601 virus,suggesting that ICP0 may act as an activator of viral gene expression in permissive cells.Collectively,these data suggest that increased ICP0 m RNA by suppressed LAT did not affect the establishment of latency in latently infected murine ganglia.Haifang Jiang Jiaming Wu Xianjie Liu Ruitao Lu Manling Zhou Meiling Chen Yonghong Liu Grace Guoying Zhou Wenmin Fu 2021Virologica Sinica2021,36,2:2
11Biomarkers of aging显示文摘Aging biomarkers are a combination of biological parameters to(i)assess age-related changes,(ii)track the physiological aging process,and(iii)predict the transition into a pathological status.Although a broad spectrum of aging biomarkers has been developed,their potential uses and limitations remain poorly characterized.An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research:How old are we?Why do we get old?And how can we age slower?This review aims to address this need.Here,we summarize our current knowledge of biomarkers developed for cellular,organ,and organismal levels of aging,comprising six pillars:physiological characteristics,medical imaging,histological features,cellular alterations,molecular changes,and secretory factors.To fulfill all these requisites,we propose that aging biomarkers should qualify for being specific,systemic,and clinically relevant.Aging Biomarker Consortium Hainan Bao Jiani Cao Mengting Chen Min Chen Wei Chen Xiao Chen Yanhao Chen Yu Chen Yutian Chen Zhiyang Chen Jagadish K Chhetri Yingjie Ding Junlin Feng Jun Guo Mengmeng Guo Chuting He Yujuan Jia Haiping Jiang Ying Jing Dingfeng Li Jiaming Li Jingyi Li Qinhao Liang Rui Liang Feng Liu Xiaoqian Liu Zuojun Liu Oscar Junhong Luo Jianwei Lv Jingyi Ma Kehang Mao Jiawei Nie Xinhua Qiao Xinpei Sun Xiaoqiang Tang Jianfang Wang Qiaoran Wang Siyuan Wang Xuan Wang Yaning Wang Yuhan Wang Rimo Wu Kai Xia Fu-Hui Xiao Lingyan Xu Yingying Xu Haoteng Yan Liang Yang Ruici Yang Yuanxin Yang Yilin Ying Le Zhang Weiwei Zhang Wenwan Zhang Xing Zhang Zhuo Zhang Min Zhou Rui Zhou Qingchen Zhu Zhengmao Zhu Feng Cao Zhongwei Cao Piu Chan Chang Chen Guobing Chen Hou-Zao Chen Jun Chen Weimin Ci Bi-Sen Ding Qiurong Ding Feng Gao Jing-Dong JHan Kai Huang Zhenyu Ju Qing-Peng Kong Ji Li Jian Li Xin Li Baohua Liu Feng Liu Lin Liu Qiang Liu Qiang Liu Xingguo Liu Yong Liu Xianghang Luo Shuai Ma Xinran Ma Zhiyong Mao Jing Nie Yaojin Peng Jing Qu Jie Ren Ruibao Ren Moshi Song Zhou Songyang Yi Eve Sun Yu Sun Mei Tian Shusen Wang Si Wang Xia Wang Xiaoning Wang Yan-Jiang Wang Yunfang Wang Catherine CL Wong Andy Peng Xiang Yichuan Xiao Zhengwei Xie Daichao Xu Jing Ye Rui Yue Cuntai Zhang Hongbo Zhang Liang Zhang Weiqi Zhang Yong Zhang Yun-Wu Zhang Zhuohua Zhang Tongbiao Zhao Yuzheng Zhao Dahai Zhu Weiguo Zou Gang Pei Guang-Hui Liu 2023Science China(Life Sciences)2023,66,5:2
12Synergistic effect of EMS1-shRNA and sorafenib on proliferation, migration, invasion and endocytosis of SMMC-7721显示文摘Jiaming Zhou Li Chen Yixin Zhang Yuanyuan Wu Guilan Wang Song He Zhongying Guo Yingze Wei 2014Journal of Molecular Histology2014,,:1
13Tuning exsolution of nanoparticles in defect engineered layered perovskite oxides for efficient CO_(2) electrolysis显示文摘Solid oxide electrolysis cell(SOEC) could be a potential technology to afford chemical storage of renewable electricity by converting water and carbon dioxide.In this work,we present the Ni-doped layered perovskite oxides,(La_(4)Sr_(n-4))_(0.9)Ti_(0.9n)Ni_(0.1n)O_(3n+2) with n=5,8,and 12(LSTNn) for application as catalysts of CO_(2) electrolysis with the exsolution of Ni nanoparticles through a simple in-situ growth method.It is found that the density,size,and distribution of exsolved Ni nanoparticles are determined by the number of n in LSTNn due to the different stack structures of TiO_6 octahedra along the c axis.The Ni doping in LSTNn significantly improved the electrochemical activity by increasing oxygen vacancies,and the Ni metallic nanoparticles afford much more active sites.The results show that LSTNn cathodes can successfully be manipulated the activity by controlling both the n number and Ni exsolution.Among these LSTNn(n=5,8,and 12),LSTN8 renders a higher activity for electrolysis of CO_(2) with a current density of 1.50A cm^(-2)@2.0 V at 800℃ It is clear from these results that the number of n in(La_(4)Sr_(n-4))_(0.9)Ti_(0.9n)Ni_(0.1n)O_(3n+2)with Ni-doping is a key factor in controlling the electrochemical performance and catalytic activity in SOEC.Zhengrong Liu Jun Zhou Yueyue Sun Xiangling Yue Jiaming Yang Lei Fu Qinyuan Deng Hongfei Zhao Chaofan Yin Kai Wu 2023Journal of Energy Chemistry2023,,9:1
14Dynamically reconfigurable subwavelength optical device for hydrogen sulfide gas sensing显示文摘The importance of tunable subwavelength optical devices in modern electromagnetic and photonic systems is indisputable.Herein,a lithography-free,wide-angle,and reconfigurable subwavelength optical device with high tunability operating in the near-infrared regions is proposed and experimentally demonstrated,based on a reversible nanochemistry approach.The reconfigurable subwavelength optical device basically comprises an ultrathin copper oxide(CuO)thin film on an optical thick gold substrate by utilizing the reversible chemical conversion of CuO to sulfides upon exposure to hydrogen sulfide gas.Proof-of-concept experimental results show that the maximal modulation depth of reflectance can be as high as 90%at the wavelength of 1.79μm with the initial thickness of CuO taken as 150 nm.Partially reflected wave calculations combined with the transfer matrix method are employed to analytically investigate the optical properties of the structure,which show good agreement with experimental results.We believe that the proposed versatile approaches can be implemented for dynamic control management,allowing applications in tunable photonics,active displays,optical encryption,and gas sensing.ZHENGJI WEN JIALIANG LU WEIWEI YU HAO WU HAO XIE XIAOHANG PAN QIANQIAN XU ZIJI ZHOU CHONG TAN DONGJIE ZHOU CHANG LIU YAN SUN NING DAI JIAMING HAO 2021Photonics Research2021,9,10:1
15Nearly Total Absorption of Light and Heat Generation by Plasmonic Metamaterials 显示文摘Hao Jiaming Zhou Lei Qiu Min 2011Physical Review2011,83,16:1
16Intermedin/adrenomedullin 2 protects against tubular cell hypoxia‐reoxygenation injury in vitro by promoting cell proliferation and upregulating cyclin D 1 expression显示文摘Yanhong Wang Rongshan Li Xi Qiao Jihua Tian Xiaole Su Ruiping Wu Ruijing Zhang Xiaoshuang Zhou Jiaming Li Shan Shao 2013Nephrology2013,,9:1
17CoSe_(2)/MoS_(2) Heterostructures to Couple Polysulfide Adsorption and Catalysis in Lithium-Sulfur Batteries显示文摘Lithium-sulfur batteries have been regarded as one of most promising next-generation energy storage devices because of their high energy density and low cost.However,polysulfide shuttling and slow kinetics hinder the practical application.We fabricated hierarchically heterostructured CoSe_(2)/MoS_(2) nanoarrays on carbon clothes as the sulfur cathode host.The resulting heterostructures facilitate electron conduction and improve electrolyte wetting.More importantly,the composite heterostructures couple the strong poly-sulfide adsorption of CoSe_(2) and high catalytic activity of MoS_(2) to synergistically accelerate polysulfide conversion,demonstrating higher catalytic activity than their individual components.Zihan Shen Qingwen Zhou Huiling Yu Jiaming Tian Man Shi Chaoquan Hu Huigang Zhang 2021Chinese Journal of Chemistry2021,39,5:1
18Electromagnetic wave scatterings by anisotropic metamaterials:Generalized 4 * 4 transfermatrix methods显示文摘Has Jiaming Lei Zhou 2008Phys Rev B2008,77,09:1
19Cerium and ruthenium co-doped La_(0.7)Sr_(0.3)FeO_(3-δ) as a high-efficiency electrode for symmetrical solid oxide fuel cell显示文摘Symmetrical solid oxide fuel cells(SSOFCs)could be alternative energy conversion devices due to their simple fabrication process and low cost.Herein,perovskite La_(0.6)Ce_(0.1)Sr_(0.3)Fe_(0.95)Ru_(0.05O3-δ)(LCSFR)was synthesized and evaluated as a high-performance electrode for SSOFCs based on the electrolyte of La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3-δ)(LSGM).LCSFR retains their stable perovskite crystal structure in both reducing and oxidizing atmospheres,though a minor amount of LaSrFeO4 phase is present under reducing conditions.Morphology investigation shows that homogeneously dispersed Ru metallic nanoparticles are exsolved on the surface of LCSFR after being reduced.The polarization resistance(Rp)of LCSFR-CGO(Ce_(0.9)Gd_(0.1O2-δ))is about 0.11Ω·cm^(2)at 800℃in air,while the value of Rp for LCSFR-CGO in wet H_(2)(3%H_(2)O)increases up to 0.32Ω·cm^(2).The symmetrical LCSFR-CGOILSGMILCSFR-CGO cell demonstrates a performance with an open circuit potential(OCV)of 1.07 V and a maximum peak power density of 904 mW/cm^(2)at 800℃using wet H2 as the fuel.This high performance indicates that LCSFR is a candidate electrode for SSOFCs.Junkai Wang Lei Fu Jiaming Yang Ke Wu Jun Zhou Kai Wu 2021Journal of Rare Earths2021,39,9:1
20Growth of α-HgI2 single crystals from physical vapor trans- port in an oil-bath furnace显示文摘Zhou Hantang Lee Chenghsu Chung Jiaming 2003Mater Res Bull2003,38,15:1
返回顶部 每页显示:
共3页 首页 上一页 第1页 下一页 末页 /3 跳转

网站首页 | 关于我们 | 联系我们 | 产品服务 | 客服中心 | 广告服务 | 版权声明 | 网站联盟 | 友情链接 | 售卡网点

版权所有© 渝B2-20050021-1 渝公网安备 50019002500403号 违法和不良信息举报中心

互联网出版许可证 新出网证(渝)字10号 全国400电话 - 免长途话费