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| 1 | Existence of periodic and subharmonic solutions for second-order superlinear difference equations显示文摘By critical point theory, a new approach is provided to study the existence and multiplicity results of periodic and subharmonic solutions for difference equations. For secord-order difference equations △2xn-1 + f(n,xn) = 0,some new results are obtained for the above problems when f(t, z) has superlinear growth at zero and at infinity in z. | 郭志明 庾建设 | 2003 | Science China Mathematics2003，46，4： | 51 |
| 2 | 西南典型喀斯特地区石漠化时空演变特征--以贵州省普定县为例显示文摘为揭示我国西南典型喀斯特地区石漠化时空演变特征,选取贵州省普定县为研究对象,基于Landsat、DEM等影像数据,提取了坡度和4期植被覆盖度、岩石裸露率分布图,并利用地理探测器获得各自的贡献率,反演了1990—2015年4期石漠化空间分布信息,进而讨论了石漠化时空演变特征。结果表明:(1)在1990—2015年间,普定县石漠化演变复杂,经历了由好转到恶化再到好转的阶段,总体趋势在好转,局部恶化,石漠化治理仍需加大力度;(2)中度以上石漠化集中分布在三岔河沿岸附近,轻度以下石漠化则分布较散乱;(3)潜在和轻度石漠化演变方向复杂,潜在石漠化平均变化速率最大(2.75 km2/a),在1997—2006年间更是达到了16.5 km2/a;(4)植被覆盖度与岩石裸露率的变化主要呈负相关,前者的增加主导了石漠化的好转,而后者的增加则控制了石漠化的恶化;(5)石漠化演变存在突变,在三岔河沿岸附近,存在无/潜在石漠化突变为重度以上石漠化的现象;在靠近城乡居民地附近,存在重度以上石漠化突变为无/潜在石漠化的现象;(6)植被覆盖度、岩石裸露率、坡度能较准确反演石漠化,贡献率分别为44%、42%、14%。本文提供的石漠化反演方法快速高效,制作的图件、数据为同行提供了参考,得出的结论为石漠化治理提供了科学支撑。 | 习慧鹏 王世杰 白晓永 唐红 吴路华 陈飞 肖建勇 王明明 李汇文 操玥 陈欢 冉晨 罗旭玲 | 2018 | 生态学报2018，38，24： | 33 |
| 3 | The characteristics of atmospheric CO_2 concentration variation of four national background stations in China显示文摘Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concen- tration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution. | LIU LiXin, ZHOU LingXi, ZHANG XiaoChun, WEN Min, ZHANG Fang, YAO Bo & FANG ShuangXi Key Laboratory for Atmospheric Chemistry, Centre for Atmosphere Watch and Services (CAWAS), Chinese Academy of Meteoro- logical Sciences (CAMS), China Meteorological Administration (CMA), Beijing 100081, China | 2009 | Science China Earth Sciences2009，52，11： | 26 |
| 4 | Kinematics Modeling and Experiments of Pectoral Oscillation Propulsion Robotic Fish显示文摘A robotic fish driven by oscillating fins, 'Cownose Ray-I', is developed, which is in dorsoventrally flattened shape withouta tail. The robotic fish is composed of a body and two lateral fins. A three-factor kinematic model is established and used in thedesign of a mechanism. By controlling the three kinematic parameters, the robotic fish can accelerate and maneuver. Forwardvelocity is dependent on the largest amplitude and the number of waves in the fins, while the relative contribution of fin beatfrequency to the forward velocity of the robotic fish is different from the usual result. On the other hand, experimental results onmaneuvering show that phase difference has a stronger effect on swerving than the largest amplitude to some extent. In addition,as propulsion waves pass from the trailing edge to the leading edge, the robotic fish attains a backward velocity of 0. 15 m·s-1. | Shao-bo Yang,Jing Qiu,Xiao-yun HanInstitute of Mechatronical Engineering and Automatization,National University of Defense Technology,Changsha 410073,P.R.China | 2009 | Journal of Bionic Engineering2009，6，2： | 25 |
| 5 | Use of venous-to-arterial carbon dioxide tension difference to guide resuscitation therapy in septic shock显示文摘The mixed venous-to-arterial carbon dioxide(CO_2)tension difference[P(v-a) CO_2]is the difference between carbon dioxide tension(PCO_2) in mixed venous blood(sampled from a pulmonary artery catheter) and the PCO_2 in arterial blood.P(v-a) CO_2 depends on the cardiac output and the global CO_2 production,and on the complex relationship between PCO_2 and CO_2 content.Experimental and clinical studies support the evidence that P(v-a) CO_2 cannot serve as an indicator of tissue hypoxia,and should be regarded as an indicator of the adequacy of venous blood to wash out the total CO_2generated by the peripheral tissues.P(v-a) CO_2 can be replaced by the central venous-to-arterial CO_2 difference(△PCO_2),which is calculated from simultaneous sampling of central venous blood from a central vein catheter and arterial blood and,therefore,more easy to obtain at the bedside.Determining the △PCO_2 during the resuscitation of septic shock patients might be useful when deciding when to continue resuscitation despite a central venous oxygen saturation(SCVO_2) > 70%associated with elevated blood lactate levels.Because high blood lactate levels is not a discriminatory factor in determining the source of that stress,an increased △PCO_2(> 6 mmHg)could be used to identify patients who still remain inadequately resuscitated.Monitoring the △PCO_2 from the beginning of the reanimation of septic shock patients might be a valuable means to evaluate the adequacy of cardiac output in tissue perfusion and,thus,guiding the therapy.In this respect,it can aid to titrate inotropes to adjust oxygen delivery to CO_2 production,or to choose between hemoglobin correction or fluid/inotrope infusion in patients with a too low ScvO_2 related to metabolic demand.The combination of P(v-a) CO_2 or △PCO_2 with oxygen-derived parameters through the calculation of the P(v-a) CO_2 or △PCO_2/arteriovenous oxygen content difference ratio can detect the presence of global anaerobic metabolism. | Jihad Mallat Malcolm Lemyze Laurent Tronchon Beno?t Vallet Didier Thevenin | 2016 | World Journal of Critical Care Medicine2016，5，1： | 25 |
| 6 | Combined APACH Ⅱ score and arterial blood lactate clearance rate to predict the prognosis of ARDS patients显示文摘Objective:To explore the easily applicable indicators of practical value to evaluate the prognosis of acute respiratory distress syndrome(ARDS).Methods:Blood and biochemical tests and bloodgas analyses were performed upon entry into the ICUs,12 h,24 h,48 h and 72 h after that in 72 ARDS patients(who were admitted to the ICUs of our hospital from January 2000 to December 2009).Then APACHEⅡscores were achieved by combining relevant physiological parameters and laboratory results.Results:There was a statistical difference between the death group and survival group at different time points upon entering the ICUs in terms of APACHEⅡscore, alveolar-arterial oxygen difference and arterial blood lactate clearance rate.PaO2/FiO2 values were recorded to be statistically different between the death group and survival group 24 h,48 h and 72 h,respectively after entry into the ICUs.In addition,registered linear regression existed between APACHEⅡscore,alveolar-arterial oxygen difference or PaO2/FiO2 value and time. APACHEⅡscore 24 h and 72 h after entering ICUs predicted mortality with an area under the ROC curve(AUC) standing respectively at 0.919 and 0.9SS.Arterial blood lactate clearance rate 12 h, 24 h,48 h and 72 h after entering ICUs predicted mortality with an area under the ROC curve (AUC) at 0.918,0.918,0.909 and 0.991,respectively.Conclusions:APACHEⅡscore applied in combination with arterial blood lactate clearance rate is of clinical significance in assessing the prognosis of ARDS patients. | Wen-Hui Wu Yuan-Yuan Niu Chang-Ran Zhang Long-Bin Xiao Hui-Shao Ye De-Mao Pan Mian Zeng | 2012 | Asian Pacific Journal of Tropical Medicine2012，5，8： | 21 |
| 7 | Finite difference scheme based on proper orthogonal decomposition for the nonstationary Navier-Stokes equations显示文摘The proper orthogonal decomposition(POD)and the singular value decomposition(SVD) are used to study the finite difference scheme(FDS)for the nonstationary Navier-Stokes equations. Ensembles of data are compiled from the transient solutions computed from the discrete equation system derived from the FDS for the nonstationary Navier-Stokes equations.The optimal orthogonal bases are reconstructed by the elements of the ensemble with POD and SVD.Combining the above procedures with a Galerkin projection approach yields a new optimizing FDS model with lower dimensions and a high accuracy for the nonstationary Navier-Stokes equations.The errors between POD approximate solutions and FDS solutions are analyzed.It is shown by considering the results obtained for numerical simulations of cavity flows that the error between POD approximate solution and FDS solution is consistent with theoretical results.Moreover,it is also shown that this validates the feasibility and efficiency of POD method. | Zhen-dong LUO Rui-wen WANG Jiang ZHU | 2007 | Science China Mathematics2007，50，8： | 20 |
| 8 | Finite difference method and analysis for three-dimensional semiconductor device of heat conduction显示文摘The mathematical model of the three-dimensional semiconductor devices of heat conduction is described by a system of four quasilinear partial differential equations for initial boundary value problem. One equation in elliptic form is for the electric potential; two equations of convection-dominated diffusion type are for the electron and hole concentration; and one heat conduction equation is for temperature. Characteristic finite difference schemes for two kinds of boundary value problems are put forward. By using the thick and thin grids to form a complete set and treating the product threefold-quadratic interpolation, variable time step method with the boundary condition, calculus of variations and the theory of prior estimates and techniques, the optimal error estimates in L2 norm are derived in the approximate solutions. | 袁益让 | 1996 | Science China Mathematics1996，39，11： | 19 |
| 9 | Estimates for the zeros of differences of meromorphic functions显示文摘Let f be a transcendental meromorphic function and g(z)=f(z+c1)+f(z+c2)-2f(z) and g2(z)=f(z+c1)·f(z+c2)-f2(z).The exponents of convergence of zeros of differences g(z),g2(z),g(z)/f(z),and g2(z)/f2(z) are estimated accurately. | SHON Kwang Ho | 2009 | Science China Mathematics2009，52，11： | 18 |
| 10 | A new method for judging the computational stability of the difference schemes of nonlinear evolution equations显示文摘For the non-conservative difference schemes of nonlinear evolution equations with aperiodic boundary conditions, taken one-dimensional nonlinear advection equation as an example, a new method for judging the computational stability is given. It is proved to be practical and effective through several numerical examples. The stability criteria obtained by this method are really the necessary conditions of computational stability. | LIN Wantao Jl Zhongzhen WANG Bin YANG Xiaozhong | 2000 | Chinese Science Bulletin2000，45，15： | 18 |
| 11 | EXISTENCE OF ALMOST PERIODIC SOLUTIONS FOR DIFFERENCE SYSTEMS显示文摘In this work, we first define the notions of almost periodic sequences, asymptotically almost periodic sequences, as well as uniformly almost periodic sequences,and reveal their basic properties. Then for the almost periodic difference systems of general form we establish the criteria of existence for almost periodic solutions.Especially, several existence theorems are proved in terms of discrete Liapunov functions. | 张书年 | 2000 | Annals of Differential Equations2000，16，2： | 17 |
| 12 | Self-memorization Equation in Atmospheric Motion显示文摘In view of the fact that the atmospheric motion isan irreversible process, a memory function which can recall observational data in the past is suggested. In terms of defining an inner product in Hilbert space, a new concept of self-memorization in the atmospheric motion is proposed, thus the traditional atmospheric motion equation is generalized to a self-memorization equation in inclusion of multi-time observations. Self-memorization equations of a barotropic nondivergent model and a barotropic primitive equation model are exemplified.It is proved that some existing difference schemes can be derived from the self-memorization equation by giving particular values to memory function. However, it demonstrates that multi-time numerical prediction models can be unified into a framework of self-memorization equation. If a stochastic method in solving the memory function is taken, the selfmemorization equation will be transformed to a sort of dynamic-stochastic prediction model. | 曹鸿兴 | 1993 | Science China Chemistry1993，36，7： | 16 |
| 13 | Hanning self-convolution window and its application to harmonic analysis显示文摘The Hanning self-convolution window (HSCW) is proposed in this paper. And the phase difference correction algorithm based on the discrete spectrum and the HSCW is given. The HSCW has a low peak side lobe level, a high side lobe roll-off rate, and a simple spectrum representation. Hence, leakage errors and harmonic interferences can be considerably reduced by weighting samples with the HSCW, the parameter estimation by the HSCW-based phase difference correction algorithm is free of solving high order equations, and the overall method can be easily implemented in embedded systems. Simulation and application results show that the HSCW-based phase difference correction algorithm can suppress the impacts of fundamental frequency fluctuation and white noise on harmonic parameter estimation, and the HSCW is advantageous over existing combined cosine windows in terms of harmonic analysis performance. | WEN He TENG ZhaoSheng GUO SiYu WANG JingXun YANG BuMing WANG Yi CHEN Tao | 2009 | Science China(Technological Sciences)2009，52，2： | 15 |
| 14 | Rare earth upconversion nanophosphors: synthesis, functionalization and application as biolabels and energy transfer donors显示文摘This review focused on rare earth upconversion nanophosphors (UCNPs), a particular class of emitters whose photoluminescence mechanism is of fundamental difference from that of conventional dyes and semiconductor quantum dots. We in the first section gave a brief summary on a variety of synthetic methodologies developed during the past decades. Instead of presenting an exhaustive reference list, we selected only a few representative examples, illustrating the merits and limits of each involved synthetic route. Then we surveyed the recent progress in the functionalization techniques for these nanomaterials, depicting the modification in microstructures and improvement in properties with respect to the parent nanoparticles. And finally, we emphasized their application in the research fields of biolabeling and energy transfer, narrating their superior performance benefiting from the unique excitation and emission properties. | 张超 孙聆东 张亚文 严纯华 | 2010 | Journal of Rare Earths2010，28，6： | 14 |
| 15 | 传感器并联型局部放电监测与定位方法显示文摘局部放电监测作为绝缘诊断的重要手段,因其能在早期及时有效地发现电气设备的绝缘缺陷,正为电力部门所推广。然而目前变电站局部放电在线监测都是针对单个设备进行的,要对变电站多设备实施监测,需要安装多个监测装置,存在成本高、系统维护工作量大等问题。本文提出了一种基于传感器并联结构的低成本变电站多设备局部放电监测与初定位方法。该方法通过在一环状信号总线上并联多个安装在不同设备的局部放电传感器,达到仅用一套采集系统监控多个设备的目的,同时利用各个传感器所检测的局部放电脉冲信号到达信号总线两端的时差固定且各自不同,实现局部放电源的初定位。在阐述该新型局部放电监测与初定位原理基础上,本文还对实现该原理的监测系统结构、定位算法进行了初步研究,并进行了实验验证。 | 高鹏路 胡岳 刘斌 曹灵钰 江秀臣 盛戈皞 | 2014 | 电工技术学报2014，29，2： | 14 |
| 16 | HAMILTONIAN ALGORITHMS FOR HAMILTONIAN DYNAMICAL SYSTEMS | 冯康 秦孟兆 | 1991 | Progress in Natural Science:Materials International1991，1，2： | 14 |
| 17 | 固定化藻菌去除淡水养殖废水氨氮效果及模型拟建(摘要)(英文)显示文摘[目的]研究固定化藻菌去除水养殖废水氨氮效果及模型拟建。[方法]利用固定化藻菌(ABI)处理淡水养殖废水中的氨氮,采用多因子正交试验得到温度(T)、PH、光照强度(I)、溶解氧(DO)和填充率五因子与氨氮去除率(AR)之间的关系数据,拟建五因子与氨氮去除率关系模型。[结果]五因子对氨氮去除率均具有显著影响,最佳去氨氮组合为,温度30℃、pH值7.0、光照强度6000lx、溶解氧5.0mg/L、填充率10%。根据实验数据拟建的方程模型决定系数R2=0.8648,相伴概率P<0.05,对氨氮去除率的模型预测值与实际测值进行样本T-检验,结果表明总体均值差异显著值sig.为0.978(P>0.05),模型预测值与实际测值数据组无显著性差异,模型具有较高拟合度。[结论]为实现养殖废水中氨氮去除或浓度降低提供参考依据。 | 邹万生 张景来 刘良国 邓武军 | 2010 | Agricultural Science & Technology2010，11，5： | 14 |
| 18 | Characteristic Finite Difference Methods for Moving Boundary Value Problem of Numerical Simulation of Oil Deposit显示文摘The software for oil-gas transport and accumulation is to describe the history of oil-gas transport and accumulation in basin evolution. It is of great value in rational evaluation of prospecting and exploiting oil-gas resources. The mathematical model can be described as a coupled system of nonlinear partial differential equations with moving boundary value problem. This paper puts forward a kind of characteristic finite difference schemes, and derives from them optimal order estimates in l^2 norm for the error in the approximate solutions. The research is important both theoretically and practically for the model analysis in the field, for model numerical method and for software development. | 袁益让 | 1994 | Science China Mathematics1994，37，12： | 12 |
| 19 | Utility of linked color imaging for endoscopic diagnosis of early gastric cancer显示文摘BACKGROUND Linked color imaging(LCI) is a method of endoscopic imaging that emphasizes slight differences in red mucosal color.AIM To evaluate LCI in diagnostic endoscopy of early gastric cancer and to compare LCI and pathological findings.METHODS Endoscopic images were obtained for 39 patients(43 lesions) with early gastric cancer. Three endoscopists evaluated lesion recognition with white light imaging(WLI) and LCI. Color values in Commission Internationale de l'Eclairage(CIE)1976 L*a*b* color space were used to calculate the color difference(ΔE) between cancer lesions and non-cancer areas. After endoscopic submucosal dissection,blood vessel density in the surface layer of the gastric epithelium was evaluated pathologically. The identical region of interest was selected for analyses of endoscopic images(WLI and LCI) and pathological analyses.RESULTS LCI was superior for lesion recognition(P < 0.0001), and ΔE between cancer and non-cancer areas was significantly greater with LCI than WLI(29.4 vs 18.6, P <0.0001). Blood vessel density was significantly higher in cancer lesions(5.96% vs4.15%, P = 0.0004). An a* cut-off of ≥ 24 in CIE 1976 L*a*b* color space identified a cancer lesion using LCI with sensitivity of 76.7%, specificity of 93.0%, and accuracy of 84.9%.CONCLUSION LCI is more effective for recognition of early gastric cancer compared to WLI as a result of improved visualization of changes in redness. Surface blood vessel density was significantly higher in cancer lesions, and this result is consistent with LCI image analysis. | Toshihisa Fujiyoshi Ryoji Miyahara Kohei Funasaka Kazuhiro Furukawa Tsunaki Sawada Keiko Maeda Takeshi Yamamura Takuya Ishikawa Eizaburo Ohno Masanao Nakamura Hiroki Kawashima Masato Nakaguro Masahiro Nakatochi Yoshiki Hirooka | 2019 | World Journal of Gastroenterology2019，25，10： | 12 |
| 20 | THE LIMITING CASE OF THIELE'S INTERPOLATING CONTINUED FRACTION EXPANSION显示文摘By means of the determinantal formulae for inverse and reciprocal differences with coincident data points, the limiting case of Thiele’s interpolating continued fraction expansion is studied in this paper and given numerical example shows that the limiting Thiele’s continued fraction expansion can be determined once for all instead of carrying out computations for each step to obtain each convergent as done in [3]. | Jie-qing Tan (Institute of Applied Mathematics, College of Science and CAD/CG Division College of Computer & Information Hefei, University of Technology, Hefei 230009, China) | 2001 | Journal of Computational Mathematics2001，19，4： | 12 |
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