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| 1 | Cold-chain food contamination as the possible origin of COVID-19 resurgence in Beijing显示文摘COVID-19,caused by SARS-CoV-2[1,2],has been contained in China through stringent non-pharmaceutical interventions.Border control and quarantine have effectively prevented the virus from being spread by infected travellers,but the risk of resurgence caused by other routes of introduction and transmission remains unclear,and current strategies to prevent resurgence could be flawed.Since July,SARS-CoV-2 RNA contaminations in frozen food imported from countries with ongoing epidemics have been reported in nine provinces in China[3,4].However,there is no robust evidence of COVID-19 outbreaks initiated by environmentto-human transmission.Here we add to evidence of such transmission by investigating the recent COVID-19 resurgence in Beijing. | Xinghuo Pang Lili Ren Shuangsheng Wu Wentai Ma Jian Yang Lin Di Jie Li Yan Xiao Lu Kang Shichang Du Jing Du Jing Wang Gang Li Shuguang Zhai Lijuan Chen Wenxiong Zhou Shengjie Lai Lei Gao Yang Pan Quanyi Wang Mingkun Li Jianbin Wang Yanyi Huang Jianwei Wang COVID-19 Field Response Group COVID-19 Laboratory Testing Group | 2020 | National Science Review2020，7，12： | 51 |
| 2 | Quasi-static Analysis of Thrust-loaded Angular Contact Ball Bearings Part Ⅰ:Theoretical Formulation显示文摘Ball bearings play an important role in various rotating machineries,but the complicated kinematic and tribological features of ball bearings make many aspects of their operating behaviors still inconclusive.Most theoretical analyses of ball bearings up to date are based on either the hypothesis of race control or other empirical models to determine the ball motion of ball bearings,but none of these strategies can reveal and consequently employ the intrinsic coupling mechanism between the spin and the tangential traction of contacting bodies rolling upon one another.To remedy the deficiency of current analytical models for ball bearing analysis,the rolling contact theory is employed to establish an explicit link between motions and interactions within ball bearings.A differential slip model is established to precisely define the slip component due to the significant curvature of the common contact patches between the ball and inner/outer raceways.The creepage and the spin ratio are formulated to accurately define the relative rigid motion between the ball and the inner/outer raceway.Then a quasi-static analytical model is established that can accurately determine the motions of the balls and races of the ball bearing.It can also give a vivid description of the slip and traction distributions within the contact area.The analytical model can be effectively used to analyze the operational conditions and tribological features of solid-lubricated ball bearings.It can also be used optimize the construction of ball bearings for specific applications. | CHEN Wenhua1,2,MA Zikui1,GAO Liang1,LI Xinglin3,and PAN Jun2 1 Institute of Mechanical Design,Zhejiang University,Hangzhou 310027,China 2 Institute of Mechanical Design and Manufacturing,Zhejiang Sci-Tech University,Hangzhou 310018,China 3 State Testing Laboratory of Hangzhou Bearing Test & Research Center,Hangzhou 310022,China | 2012 | Chinese Journal of Mechanical Engineering2012，25，1： | 16 |
| 3 | Experimental studies on perturbed acoustic resonant spectroscopy by a small rock sample in a cylindrical cavity显示文摘A measurement system for acoustic resonant spectroscopy (ARS) is estab-lished,and the effects of resonant cavity geometry,inner perturbation samples and envi-ronmental temperature on the ARS are investigated. The ARSs of the small samples with various sizes and acoustic properties are measured. The results show that at the normal pressure,the resonant frequency decreases gradually with the increase of liquid tem-perature in the cylindrical cavity,while the resonant amplitude increases. At certain pres-sure and temperature,both the resonant frequency and the amplitude decrease greatly when there exist air bubbles inside the cavity fluid. The ARS is apparently affected by the sample porosity and the sample location in the resonant cavity. At the middle of the cavity,the resonant frequencies reach their maximum values for all of the measurement samples. The resonant frequencies of the porous rock samples are smaller than those of the com-pacted samples if other acoustic parameters are the same. As the sample is moved from the top to the middle of the cavity along its axis,the resonant amplitude increases gradu-ally for the compacted rocks while decreases for the unconsolidated rocks. Furthermore,the resonant amplitude increases firstly and then decreases if the porosity of the rock sample is relatively small. In addition,through the comparisons between the experimental and theoretical results,it is found that the effects of the acoustic parameters and sizes of the samples and the size of the cylindrical cavity on the laboratory results agree well with the theoretical ones qualitatively. These results may provide basic reference for the ex-periment study of rock acoustic properties in a low frequency using ARS. | CHEN Dehua1,2,WANG Xiuming2,3,CONG Jiansheng1,XU Delong1,SONG Yanjie1 & MA Shuilong4 1. Department of Geophysics,Daqing Petroleum Institute,Daqing 163318,China 2. Institute of Acoustics,Chinese Academy of Sciences,Beijing 100080,China 3. Division of Petroleum,Australian Commonwealth Scientific and Industrial Research Organization,Bent-ley WA 6102,Australia 4. Daqing Testing and Technology Services Corporation,Daqing 163153,China | 2006 | Science China(Physics,Mechanics & Astronomy)2006，49，6： | 8 |
| 4 | Quasi-static Analysis of Thrust-loaded Angular Contact Ball Bearings Part Ⅱ:Results and Discussion显示文摘Ball bearings are widely employed mechanical components characterized by high precision and quality,and usually play important roles in various rotary machines and mechanisms.Many advanced applications require a deep understanding of their various kinematic and tribological characteristics that are essential to predict the fatigue endurance,relieve the vibration and minimize the power dissipation of ball bearings in particular applications.An angular contact ball bearing under a specified operating condition is simulated with the quasi-static/creepage analytical model proposed in the preceding article.The results demonstrate that the ball bearing is a statically determinate system.That the balls spin on both inner and outer races means the ball is controlled by neither the inner nor the outer raceway.The friction between the ball and raceway renders the inner and outer contact angles unequal.The larger the coefficient of friction is,the larger the angle deviation.The tangential traction perpendicular to the rolling direction due to the spin induces a gyro-like rotation of the ball with respect to the raceway even if no inertial effects are considered.The tangential elastic compliance of contacting surfaces gives rise to locked areas within the contact patch and transforms the sliding lines from circles into spirals.The differential slip due to the close conformity of the ball and raceway makes the sliding and traction distributions asymmetric,which will influence the location of the spinning center of the ball with respect to the raceway.The quasi-static/creepage model can be used to reveal the operating behaviors of ball bearings running under steady conditions and to optimize the design of ball bearings for specific applications. | CHEN Wenhua1,2,MA Zikui1,GAO Liang1,LI Xinglin3,and PAN Jun2 1 Institute of Mechanical Design,Zhejiang University,Hangzhou 310027,China 2 Institute of Mechanical Design and Manufacturing,Zhejiang Sci-Tech University,Hangzhou 310018,China 3 State Testing Laboratory of Hangzhou Bearing Test & Research Center,Hangzhou 310022,China | 2012 | Chinese Journal of Mechanical Engineering2012，25，1： | 7 |
| 5 | Extrohospital manajement of severe mental illness: feasibility and effects of social functioning显示文摘 | Marx AJ Test MA stein LI | 1973 | Archgen Psychiatry1973，29，： | 1 |
| 6 | Practical guidelines for the community treatment of markedly impaired patients 显示文摘 | Test MA Stein LI | 1976 | Community Mental Health Journal1976，12，： | 1 |
| 7 | Training in community living 显示文摘 | Test MA | 1992 | In Liberman RP editor handbook of psychiatric rehabilitation1992，，： | 1 |
| 8 | Expert Consensus on Polymyxin Antimicrobial Susceptibility Testing and Clinical Interpretation显示文摘The polymyxins are important antimicrobial agents against antibiotic-resistant gram-negative bacilli.In 2020,the Clinical and Laboratory Standards Institute modified the clinical breakpoints for polymyxin susceptibility test by eliminating the'susceptible'interpretive category,only reporting intermediate(≤2 mg/L)and resistant(≥4 mg/L).However,the European Committee on Antimicrobial Susceptibility Testing recommended the use of clinical breakpoints of W2 mg/L as susceptible and>2 mg/L as resistant.The first-line laboratorians and clinicians in China have been perplexed by the inconsistence of international polymyxin clinical breakpoints and discouraged by the difficulty of conducting polymyxin susceptibility testing.Therefore,it is urgently needed to make it clear for the laboratorians in China to know how to accurately carry out polymyxin susceptibility testing and standardize the interpretation of susceptibility testing results.To this end,the experts from relevant fields were convened to formulate this consensus statement on the testing and clinical interpretation of polymyxin susceptibility.Relevant recommendations are proposed accordingly for laboratorians and clinicians to streamline their daily work. | Qiwen Yang Xiaoling Ma Fupin Hu Jing Zhang Tongwen Sun Baiyi Chen Yingchun Xu Youning Liu Chinese Committee on Antimicrobial Susceptibility Testing(ChiCAST) Expert Committee on Infectious Diseases,China Medical Education Association | 2021 | Chinese Medical Sciences Journal2021，36，1： | 1 |
| 9 | Continuity of care in community treatment 显示文摘 | Test MA | 1979 | New Dir Ment Health Serv1979，2，： | 1 |
| 10 | Ahemative to the hospital: a controlled study 显示文摘 | Stein LI Test MA Marx AJ | 1975 | American Journal of Psychiatry1975，132，： | 1 |
| 11 | economic benefitcost analysis 显示文摘 | Weisbrod BA Test MA Stein LL Ahemative to mental hospital treatment: Ⅱ | 1980 | Archives of General Psychiatry1980，37，： | 1 |
| 12 | The effects of antihypertensive therapy on the quality of life显示文摘 | Groog SH Levine S Teste MA | 1986 | N Engl J Med1986，314，： | 1 |
| 13 | The relationship of clinical factors and environmental opportunities to social functioning in young adults with schizophrenia显示文摘 | Angell B Test MA | | 0，，2： | 1 |
| 14 | Review on Commissioning Test of Three Gorges Power Transmission & Substation Project显示文摘Holding the greatest power transmission capacity in China, Three Gorges power transmission and substation (T&S) project is an important landmark in the | Yang Wankai1,Yin Yonghua1,Zeng Nanchao1,Wang Minxin1,Chong Zhiyi2,Ma Weimin2,Kang Jian3 1. China Electric Power Research Institute 2. State Grid Direct Current Project Construction Company Limited 3. Hubei Electric Power Test Research Institute Yang Xiaoli | 2009 | Electricity2009，20，2： | 0 |
| 15 | STUDY ON THE BEHAVIOR OF RARE EARTH IONS BY PHOSPHORESCENT PROBE METHOD显示文摘STUDYONTHEBEHAVIOROFRAREEARTHIONSBYPHOSPHORESCENTPROBEMETHOD￥GuiBinMA;FeiGAO;LiangCHENandPinYANG(DepartmentofChemistry,Shanxi... | Gui Bin MA Fei GAO Liang CHEN and Pin YANG (Department of Chemistry, Shanxi University, Taiyuan,03006) (Institute of Molecular Science,Shanxi University, Taiyuan, 030006) (Center of Test and Analysis, Shanxi University,Taiyuan,030006) | 1996 | Chinese Chemical Letters1996，7，7： | 0 |
| 16 | A New Orthorhombic Phase of ZrW_(1.6) Mo_(0.4)O_8 at Ambient Pressure显示文摘Nanocrystallite δ ′ ZrW 1.6 Mo 0.4 O 8 was prepared in the precursor route synthesis. The characterization by means of powder X ray diffraction (XRD) and selected area electron diffraction (SAED) showed it crystallized in a orthorhombic crystal system with a =0.896 9(7) nm, b =0.701 1(8) nm, c =0.596(1) nm. The possible space group is Pnnm (58) or Pnn2 (34). The compound crystallizes in a metastable phase during the synthesis process depending on temperature and crystallization time. | ZHAO Xin hua 1** , WANG Qi 1 and MA Hui 2 1. Department of Chemistry 2. Analyzing and Testing Center, Beijing Normal University, Beijing 100875, P. R. China | 2002 | Chemical Research in Chinese Universities2002，18，3： | 0 |
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