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   73026篇
  免费   4904篇
  国内免费   296篇
耳鼻咽喉   821篇
儿科学   2026篇
妇产科学   1520篇
基础医学   9958篇
口腔科学   4092篇
临床医学   6089篇
内科学   15405篇
皮肤病学   1482篇
神经病学   6100篇
特种医学   2193篇
外国民族医学   2篇
外科学   10127篇
综合类   754篇
现状与发展   1篇
一般理论   60篇
预防医学   7281篇
眼科学   1157篇
药学   4392篇
中国医学   433篇
肿瘤学   4333篇
  2023年   639篇
  2022年   1466篇
  2021年   2931篇
  2020年   1760篇
  2019年   2398篇
  2018年   2829篇
  2017年   1967篇
  2016年   2053篇
  2015年   2428篇
  2014年   3279篇
  2013年   3929篇
  2012年   5947篇
  2011年   6199篇
  2010年   3238篇
  2009年   2567篇
  2008年   4277篇
  2007年   4308篇
  2006年   3753篇
  2005年   3372篇
  2004年   2955篇
  2003年   2612篇
  2002年   2328篇
  2001年   1013篇
  2000年   1032篇
  1999年   866篇
  1998年   446篇
  1997年   339篇
  1996年   344篇
  1995年   296篇
  1994年   233篇
  1993年   218篇
  1992年   453篇
  1991年   413篇
  1990年   406篇
  1989年   394篇
  1988年   354篇
  1987年   293篇
  1986年   288篇
  1985年   282篇
  1984年   253篇
  1983年   207篇
  1982年   168篇
  1981年   150篇
  1979年   202篇
  1978年   187篇
  1975年   118篇
  1974年   133篇
  1973年   140篇
  1970年   120篇
  1969年   128篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
International Journal of Clinical Oncology - Immune-checkpoint inhibitors (ICIs) are standard treatments for metastatic non-small cell lung cancer (NSCLC). Patients with poor performance status...  相似文献   
2.
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   
3.
4.
5.
6.
7.
Neorickettsia helminthoeca (NH), the agent of salmon poisoning disease or canine neorickettiosis (CN), is a bacterial endosymbiont of the nematode Nanophyetus salmincola, and infections are spreading among specific fish‐eating mammalians. This article describes the pathologic and immunohistochemical findings associated with spontaneous NH‐induced infections in dogs from Southern Brazil. The principal pathologic findings were hypertrophy of Peyer patches and lymphadenopathy with lymphocytic proliferation, chronic interstitial pneumonia, and chronic enteritis associated with positive intralesional immunoreactivity to antigens of NH within macrophages and histiocytes. Positive immunoreactivity against canine parvovirus‐2 (CPV‐2) or/and canine distemper virus was not detected in the evaluated intestinal segments or in the samples from the cerebellum and lungs, respectively, from the dogs evaluated. These findings demonstrated that NH was involved in the enteric, pulmonary, and lymphoid lesions herein described, and provide additional information to confirm the occurrence of this bacterial endosymbiont within this geographical location. It is proposed that chronic pneumonia should be considered as a pathologic manifestation of NH‐induced infections. Additionally, our results show that the occurrences of CN seem to be underdiagnosed in Southern Brazil due to the confusion with the incidence of CPV‐2.  相似文献   
8.
9.
10.
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