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   1314318篇
  免费   97223篇
  国内免费   2135篇
耳鼻咽喉   18784篇
儿科学   43296篇
妇产科学   38508篇
基础医学   192222篇
口腔科学   35909篇
临床医学   112206篇
内科学   259399篇
皮肤病学   26943篇
神经病学   103016篇
特种医学   51484篇
外国民族医学   366篇
外科学   204199篇
综合类   27258篇
现状与发展   2篇
一般理论   339篇
预防医学   95686篇
眼科学   29575篇
药学   100495篇
  1篇
中国医学   2551篇
肿瘤学   71437篇
  2018年   12970篇
  2016年   10977篇
  2015年   12714篇
  2014年   17456篇
  2013年   26282篇
  2012年   36686篇
  2011年   39160篇
  2010年   23001篇
  2009年   21651篇
  2008年   37633篇
  2007年   40681篇
  2006年   41166篇
  2005年   40481篇
  2004年   38801篇
  2003年   37680篇
  2002年   37006篇
  2001年   58448篇
  2000年   59827篇
  1999年   51012篇
  1998年   14665篇
  1997年   13182篇
  1996年   13393篇
  1995年   12644篇
  1994年   12016篇
  1993年   11092篇
  1992年   41176篇
  1991年   40522篇
  1990年   40042篇
  1989年   38845篇
  1988年   36251篇
  1987年   35466篇
  1986年   33831篇
  1985年   32231篇
  1984年   24037篇
  1983年   20912篇
  1982年   12509篇
  1981年   11066篇
  1979年   22695篇
  1978年   15942篇
  1977年   13786篇
  1976年   13019篇
  1975年   14248篇
  1974年   16716篇
  1973年   16127篇
  1972年   15347篇
  1971年   14253篇
  1970年   13234篇
  1969年   12751篇
  1968年   12001篇
  1967年   10502篇
排序方式: 共有10000条查询结果,搜索用时 718 毫秒
1.
2.
Die Anaesthesiologie - Auch wenn für Anästhesiologen über Jahrzehnte die Prophylaxe und Therapie postoperativer Schmerzen im Rahmen des postoperativen Patientenkomforts an vorderster...  相似文献   
3.
4.
5.
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   
6.
7.
8.
Vaccination is a vital health care initiative to prevent individual and population infection. To increase vaccination rates the federal government implemented the ‘No Jab, No Pay’ policy, where eligibility for several government benefits required children to be fully vaccinated by removing ‘conscientious objections’ and expanding the age range of children whose families receive benefits. This study assesses the impact of this policy at a local area within a single medical practice community in NSW, Australia. A retrospective clinical audit was performed between 2012 and 2017 on a single general practice's vaccination records for children ≤19 years. Catch-up vaccinations were assessed based on age at vaccination. Incidence of catch-up vaccinations was assessed for each of four years before and two years after the implementation of the ‘No Jab, No Pay’ policy in January 2016, along with the age of children and vaccination(s) given. Catch-up vaccinations were assessed temporally either side of implementation of ‘No Jab, No Pay’. Comparing the average annual vaccination catch-up incidence rate of 6.2% pre-implementation (2012–2015), there was an increase to 9.2% in 2016 (p < .001) and 7.8% in 2017 (p = .027). Secondary outcome measurement of catch-up vaccination incidence rates before (2012–2015) and after (2016–2017) ‘No Jab, No Pay’ implementation showed statistically significant increases for children aged 8–11 years (3.2%–5.6%, p = .038), 12–15 years (7.5%–14.7%, p < .001) and 16–19 years (3.3%–10.2%, p < .001) along with a statistically significant reduction in children aged 1–3 years (11.4%–6.2%, p = .015). Also, catch-up rates for DTPa significantly increased after program implementation. This study demonstrates that the Australian federal government vaccination policy ‘No Jab, No Pay’ was coincident with an increase in catch-up vaccinations within a rural NSW community served by one medical practice, especially for older children.  相似文献   
9.
10.
Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100?nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability.  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