首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4348353篇
  免费   348783篇
  国内免费   14683篇
耳鼻咽喉   60323篇
儿科学   139405篇
妇产科学   114204篇
基础医学   666724篇
口腔科学   117973篇
临床医学   396993篇
内科学   790518篇
皮肤病学   107732篇
神经病学   368297篇
特种医学   169453篇
外国民族医学   753篇
外科学   656309篇
综合类   121266篇
现状与发展   24篇
一般理论   2614篇
预防医学   360315篇
眼科学   100879篇
药学   307573篇
  26篇
中国医学   11935篇
肿瘤学   218503篇
  2021年   56146篇
  2020年   35812篇
  2019年   58804篇
  2018年   74375篇
  2017年   56996篇
  2016年   63120篇
  2015年   76084篇
  2014年   110299篇
  2013年   175808篇
  2012年   124232篇
  2011年   128938篇
  2010年   125874篇
  2009年   127609篇
  2008年   115157篇
  2007年   122452篇
  2006年   131257篇
  2005年   125348篇
  2004年   126656篇
  2003年   116857篇
  2002年   106112篇
  2001年   166968篇
  2000年   162027篇
  1999年   148685篇
  1998年   71665篇
  1997年   67608篇
  1996年   65628篇
  1995年   61051篇
  1994年   54971篇
  1993年   51019篇
  1992年   106639篇
  1991年   101395篇
  1990年   97253篇
  1989年   94834篇
  1988年   87153篇
  1987年   85328篇
  1986年   80214篇
  1985年   78374篇
  1984年   65405篇
  1983年   58203篇
  1982年   47198篇
  1981年   43861篇
  1980年   41076篇
  1979年   55113篇
  1978年   44766篇
  1977年   39989篇
  1976年   36839篇
  1975年   36808篇
  1974年   39611篇
  1973年   37752篇
  1972年   35363篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
The coronavirus disease 2019 (COVID-19) pandemic has rapidly created widespread impacts on global health and the economy. Data suggest that women are less susceptible to severe illness. However, sex-disaggregated data are incomplete, leaving room for misinterpretation, and focusing only on biologic sex underestimates the gendered impact of the pandemic on women. This narrative review summarizes what is known about gender disparities during the COVID-19 pandemic and the economic, domestic, and health burdens along with overlapping vulnerabilities related to the pandemic. In addition, this review outlines recommended strategies that advocacy groups, community leaders, and policymakers should implement to mitigate the widening gender disparities related to COVID-19.  相似文献   
33.
34.
35.
The coronavirus 2019 pandemic has affected almost every aspect of health care delivery in the United States, and the emergency medicine system has been hit particularly hard while dealing with this public health crisis. In an unprecedented time in our history, medical systems and clinicians have been asked to be creative, flexible, and innovative, all while continuing to uphold the important standards in the US health care system. To continue providing quality services to patients during this extraordinary time, care providers, organizations, administrators, and insurers have needed to alter longstanding models and procedures to respond to the dynamics of a pandemic. The Emergency Medicine Treatment and Active Labor Act of 1986, or EMTALA, is 1 example of where these alterations have allowed health care facilities and clinicians to continue their work of caring for patients while protecting both the patients and the clinicians themselves from infectious exposures at the same time.  相似文献   
36.
Isolated patellofemoral arthritis is an increasingly recognized entity, and is usually associated with previous patellofemoral dysplasia or instability. Patellofemoral arthroplasty (PFA) has evolved significantly in recent years, both in terms of implant design and importantly in the understanding of appropriate patient selection. This review outlines the indications and investigations for PFA, provides a brief history of the development of contemporary implants, and presents the clinical outcomes for the prostheses most commonly used in the UK. In addition, it provides a detailed surgical technique for implantation of an onlay implant, with tips on how to optimize patellofemoral biomechanics and thus achieve a consistently good outcome.  相似文献   
37.
38.
39.
40.
Amacrine cells of the retina are conspicuously variable in their morphologies, their population demographics, and their ensuing functions. Vesicular glutamate transporter 3 (VGluT3) amacrine cells are a recently characterized type of amacrine cell exhibiting local dendritic autonomy. The present analysis has examined three features of this VGluT3 population, including their density, local distribution, and dendritic spread, to discern the extent to which these are interrelated, using male and female mice. We first demonstrate that Bax-mediated cell death transforms the mosaic of VGluT3 cells from a random distribution into a regular mosaic. We subsequently examine the relationship between cell density and mosaic regularity across recombinant inbred strains of mice, finding that, although both traits vary across the strains, they exhibit minimal covariation. Other genetic determinants must therefore contribute independently to final cell number and to mosaic order. Using a conditional KO approach, we further demonstrate that Bax acts via the bipolar cell population, rather than cell-intrinsically, to control VGluT3 cell number. Finally, we consider the relationship between the dendritic arbors of single VGluT3 cells and the distribution of their homotypic neighbors. Dendritic field area was found to be independent of Voronoi domain area, while dendritic coverage of single cells was not conserved, simply increasing with the size of the dendritic field. Bax-KO retinas exhibited a threefold increase in dendritic coverage. Each cell, however, contributed less dendrites at each depth within the plexus, intermingling their processes with those of neighboring cells to approximate a constant volumetric density, yielding a uniformity in process coverage across the population.SIGNIFICANCE STATEMENT Different types of retinal neuron spread their processes across the surface of the retina to achieve a degree of dendritic coverage that is characteristic of each type. Many of these types achieve a constant coverage by varying their dendritic field area inversely with the local density of like-type neighbors. Here we report a population of retinal amacrine cells that do not develop dendritic arbors in relation to the spatial positioning of such homotypic neighbors; rather, this cell type modulates the extent of its dendritic branching when faced with a variable number of overlapping dendritic fields to approximate a uniformity in dendritic density across the retina.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号