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   1371008篇
  免费   101750篇
  国内免费   1784篇
耳鼻咽喉   17374篇
儿科学   44090篇
妇产科学   37231篇
基础医学   206085篇
口腔科学   37802篇
临床医学   126867篇
内科学   268208篇
皮肤病学   28916篇
神经病学   112620篇
特种医学   51180篇
外国民族医学   281篇
外科学   192468篇
综合类   26204篇
现状与发展   4篇
一般理论   672篇
预防医学   116633篇
眼科学   29874篇
药学   99164篇
  6篇
中国医学   2225篇
肿瘤学   76638篇
  2019年   11672篇
  2018年   15619篇
  2017年   12154篇
  2016年   13306篇
  2015年   15324篇
  2014年   21067篇
  2013年   31476篇
  2012年   43647篇
  2011年   46185篇
  2010年   26417篇
  2009年   25651篇
  2008年   43332篇
  2007年   46075篇
  2006年   45504篇
  2005年   44303篇
  2004年   42060篇
  2003年   40285篇
  2002年   38730篇
  2001年   59440篇
  2000年   60454篇
  1999年   51216篇
  1998年   14778篇
  1997年   13372篇
  1996年   13809篇
  1995年   12872篇
  1994年   12015篇
  1993年   11240篇
  1992年   40401篇
  1991年   39662篇
  1990年   38396篇
  1989年   37091篇
  1988年   34356篇
  1987年   33477篇
  1986年   31928篇
  1985年   30164篇
  1984年   22942篇
  1983年   20042篇
  1982年   11840篇
  1979年   21687篇
  1978年   15847篇
  1977年   13185篇
  1976年   12168篇
  1975年   13169篇
  1974年   15986篇
  1973年   15761篇
  1972年   14912篇
  1971年   13924篇
  1970年   13093篇
  1969年   12354篇
  1968年   11534篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
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   
4.
5.
6.
7.
Academic output is just one aspect of a successful career as a plastic surgeon. However, for those with a strong interest in academia, the academic output of a department will likely be a key factor when deciding how to rank jobs. The aim of this study was to quantify and rank the academic output of plastic surgery units across the UK and Ireland. The Institute for Scientific Information (ISI) Web of Science Bibliometric analysis tool was used to collate cumulative (1950–2016), 10 year (2006–2016) and 3 years (2013–2015) research output data for plastic surgery units in the UK and Ireland. Sixty-six plastic surgery units were identified. Departments were ranked for each time period according to the number of papers produced, number of citations (Nc) and h-index (a measure of the impact of scientific output). The top 3 departments for number of papers in the last 10 years were The Royal Free Hospital, London (226) Broomfield Hospital, Chelmsford (218), and Morriston Hospital and Swansea (188). The top 3 for h-number were The Royal Free Hospital (21) Wythenshawe Hospital, Manchester (18) and Morriston Hospital (17). Academic output varies across plastic surgery units in the UK and Ireland. A number of departments have consistently maintained high academic outputs across the years and will be of interest to surgeons hoping to pursue a career in academia.  相似文献   
8.
9.
10.
Pharmaceutical Chemistry Journal - An HPLC-MS method for simultaneous quantitative determination of a novel gestagenic pharmaceutical and two of its metabolites in rat and rabbit blood sera was...  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