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   1391763篇
  免费   120066篇
  国内免费   10418篇
耳鼻咽喉   17338篇
儿科学   43561篇
妇产科学   37082篇
基础医学   189314篇
口腔科学   37117篇
临床医学   127799篇
内科学   285611篇
皮肤病学   32415篇
神经病学   113105篇
特种医学   57754篇
外国民族医学   310篇
外科学   216364篇
综合类   42213篇
现状与发展   15篇
一般理论   417篇
预防医学   110498篇
眼科学   29672篇
药学   99849篇
  57篇
中国医学   6332篇
肿瘤学   75424篇
  2021年   11484篇
  2018年   15333篇
  2017年   12583篇
  2016年   14544篇
  2015年   17099篇
  2014年   23490篇
  2013年   32985篇
  2012年   40975篇
  2011年   43963篇
  2010年   27895篇
  2009年   26755篇
  2008年   39647篇
  2007年   41807篇
  2006年   42863篇
  2005年   41228篇
  2004年   38486篇
  2003年   37493篇
  2002年   35222篇
  2001年   67144篇
  2000年   68931篇
  1999年   57570篇
  1998年   17354篇
  1997年   15581篇
  1996年   16482篇
  1995年   16672篇
  1994年   15429篇
  1993年   14407篇
  1992年   47374篇
  1991年   46020篇
  1990年   44148篇
  1989年   41953篇
  1988年   38921篇
  1987年   38211篇
  1986年   35953篇
  1985年   34705篇
  1984年   26416篇
  1983年   22137篇
  1982年   13873篇
  1981年   12474篇
  1980年   11739篇
  1979年   23574篇
  1978年   17083篇
  1977年   14393篇
  1976年   13189篇
  1975年   13732篇
  1974年   16096篇
  1973年   15408篇
  1972年   14181篇
  1971年   13038篇
  1970年   11884篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
1.
Die Anaesthesiologie - Phantomschmerzen haben eine hohe Prävalenz nach Majoramputationen und sind mit einer zusätzlichen Einschränkung der Lebensqualität verbunden....  相似文献   
2.
3.
Journal of Behavioral Medicine - Evidence supports the use of graphic warnings to educate the public about the health harms of smoking and suggests warnings eliciting negative emotional responses...  相似文献   
4.
Background and objective: Myocardial infarction (MI) is a common critical disease of the cardiovascular system. The process of MI is often accompanied by the excessive activation of cardiac sympathetic nerves, which leads to arrhythmia. Resiniferatoxin (RTX) is a transient receptor potential vanilloid 1 (TRPV1), involved in the cardiac sympathetic afferent reflex. However, whether RTX can reduce the occurrence of arrhythmia and exert a cardioprotective effect by inhibiting the sympathetic reflex during MI is still unknown. Methods: The left anterior descending artery of cardiac was clamped to construct a model of MI. RTX (50 μg/ml) was used by epicardial application in MI rats. Ventricular electrophysiologic properties were continuously monitored by a body surface ECG. Yrosine hydroxylase (TH) and growth associated protein 43 (GAP43) were detected by Immunofluorescence staining. Connexin43 and transforming growth factor beta receptor 1 (TGF-β1) were detected by western blot. Norepinephrine (NE) and BNP levels in blood and tissue were determined by ELISA. Cardiac function was assessed by echocardiography. Results: The ERP, APD90, QRS, QT and the Tend-Tpeak intervals in MI rats were all prolonged, but decreased after RTX treatment (n = 3, P<0.05). In contrast, the RR interval was shortened in the MI group, but prolonged in the MI+RTX group (n = 3, P<0.05). RTX treatment significantly reduced ventricular arrhythmias after MI. TH- and GAP43-positive nerve densities and TGF-β1, and cx-43 protein expression were up-regulated in the MI group compared to the sham group, and they were decreased in the MI+RTX group compared to the MI group (n = 3, P<0.05). RTX can decrease serum and tissue NE and BNP levels (n = 3, P<0.05). RTX pretreatment significantly decreased heart rate, HW/BW ratio and LVIDS, and increased LVEF andLVFS values (n = 3, P<0.05). Conclusion: RTX improved cardiac dysfunction, ventricular electrophysiologic properties, and sympathetic nerve remodeling in rats with MI by inhibiting the excessive cardiac sympathetic drive.  相似文献   
5.
Bone mineral density (BMD) is a highly heritable predictor of osteoporotic fracture. GWAS have identified hundreds of loci influencing BMD, but few have been functionally analyzed. In this study, we show that SNPs within a BMD locus on chromosome 14q32.32 alter splicing and expression of PAR-1a/microtubule affinity regulating kinase 3 (MARK3), a conserved serine/threonine kinase known to regulate bioenergetics, cell division, and polarity. Mice lacking Mark3 either globally or selectively in osteoblasts have increased bone mass at maturity. RNA profiling from Mark3-deficient osteoblasts suggested changes in the expression of components of the Notch signaling pathway. Mark3-deficient osteoblasts exhibited greater matrix mineralization compared with controls that was accompanied by reduced Jag1/Hes1 expression and diminished downstream JNK signaling. Overexpression of Jag1 in Mark3-deficient osteoblasts both in vitro and in vivo normalized mineralization capacity and bone mass, respectively. Together, these findings reveal a mechanism whereby genetically regulated alterations in Mark3 expression perturb cell signaling in osteoblasts to influence bone mass.  相似文献   
6.
7.
8.
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   
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