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   408437篇
  免费   24486篇
  国内免费   1980篇
耳鼻咽喉   5721篇
儿科学   13075篇
妇产科学   14193篇
基础医学   62271篇
口腔科学   10991篇
临床医学   32913篇
内科学   76156篇
皮肤病学   8634篇
神经病学   28612篇
特种医学   15447篇
外国民族医学   46篇
外科学   62510篇
综合类   12871篇
现状与发展   1篇
一般理论   193篇
预防医学   28192篇
眼科学   9612篇
药学   30656篇
中国医学   1594篇
肿瘤学   21215篇
  2021年   3145篇
  2019年   3239篇
  2018年   5154篇
  2017年   3762篇
  2016年   4184篇
  2015年   4849篇
  2014年   6384篇
  2013年   9507篇
  2012年   12370篇
  2011年   12999篇
  2010年   8273篇
  2009年   7493篇
  2008年   11852篇
  2007年   12871篇
  2006年   12751篇
  2005年   11917篇
  2004年   11460篇
  2003年   10750篇
  2002年   10203篇
  2001年   19692篇
  2000年   20195篇
  1999年   16863篇
  1998年   4803篇
  1997年   4120篇
  1996年   3524篇
  1995年   3361篇
  1992年   11886篇
  1991年   12089篇
  1990年   11662篇
  1989年   11489篇
  1988年   10616篇
  1987年   10248篇
  1986年   9702篇
  1985年   9373篇
  1984年   6740篇
  1983年   5832篇
  1982年   3416篇
  1979年   6276篇
  1978年   4357篇
  1977年   3674篇
  1976年   3391篇
  1975年   3972篇
  1974年   4650篇
  1973年   4727篇
  1972年   4415篇
  1971年   4153篇
  1970年   3930篇
  1969年   3673篇
  1968年   3528篇
  1967年   3238篇
排序方式: 共有10000条查询结果,搜索用时 306 毫秒
11.
12.
13.
We report a Chinese family with members affected by epidermolytic ichthyosis (EI), caused by KRT gene mutations. The proband was a 14‐year‐old boy who had simultaneous appearance of nephroblastoma and epidermolytic ichthyosis (EI). Both the patient and his mother exhibited the specific clinical and pathological manifestations of EI. We analysed all exons and flanking sequences of the KRT1 and KRT10 genes using PCR, and found that the proband and his mother had a G>C transition at nucleotide position 1432 in exon 7 of KRT1, resulting in an amino acid substitution of glutamate (GAA) to glutamine (CAA) at codon 478 (E478Q). The KRT10 gene had no mutations.  相似文献   
14.
15.
16.
Bipolar disorder (BD) is a common psychiatric mood disorder affecting more than 1-2% of the general population of different European countries. Unfortunately, there is no objective laboratory-based test to aid BD diagnosis or monitor its progression, and little is known about the molecular basis of BD. Here, we performed a comparative proteomic study to identify differentially expressed plasma proteins in various BD mood states (depressed BD, manic BD, and euthymic BD) relative to healthy controls. A total of 10 euthymic BD, 20 depressed BD, 15 manic BD, and 20 demographically matched healthy control subjects were recruited. Seven high-abundance proteins were immunodepleted in plasma samples from the 4 experimental groups, which were then subjected to proteome-wide expression profiling by two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-time-of-flight/time-of-flight tandem mass spectrometry. Proteomic results were validated by immunoblotting and bioinformatically analyzed using MetaCore. From a total of 32 proteins identified with 1.5-fold changes in expression compared with healthy controls, 16 proteins were perturbed in BD independent of mood state, while 16 proteins were specifically associated with particular BD mood states. Two mood-independent differential proteins, apolipoprotein (Apo) A1 and Apo L1, suggest that BD pathophysiology may be associated with early perturbations in lipid metabolism. Moreover, down-regulation of one mood-dependent protein, carbonic anhydrase 1 (CA-1), suggests it may be involved in the pathophysiology of depressive episodes in BD. Thus, BD pathophysiology may be associated with early perturbations in lipid metabolism that are independent of mood state, while CA-1 may be involved in the pathophysiology of depressive episodes.  相似文献   
17.
Analyzing functional species’ characteristics (species traits) that represent physiological, life history and morphological characteristics of species help understanding the impacts of various stressors on aquatic communities at field conditions. This research aimed to study the combined effects of pesticides and other environmental factors (temperature, dissolved oxygen, dissolved organic carbon, floating macrophytes cover, phosphate, nitrite, and nitrate) on the trait modality distribution of aquatic macrofauna communities. To this purpose, a field inventory was performed in a flower bulb growing area of the Netherlands with significant variation in pesticides pressures. Macrofauna community composition, water chemistry parameters and pesticide concentrations in ditches next to flower bulb fields were determined. Trait modalities of nine traits (feeding mode, respiration mode, locomotion type, resistance form, reproduction mode, life stage, voltinism, saprobity, maximum body size) likely to indicate pesticides impacts were analyzed. According to a redundancy analysis, phosphate -and not pesticides- constituted the main factor structuring the trait modality distribution of aquatic macrofauna. The functional composition could be ascribed for 2–4 % to pesticides, and for 3–11 % to phosphate. The lack of trait responses to pesticides may indicate that species may have used alternative strategies to adapt to ambient pesticides stress. Biomass of animals exhibiting trait modalities related to feeding by predation and grazing, presence of diapause form or dormancy, reproduction by free clutches and ovoviviparity, life stage of larvae and pupa, was negatively correlated to the concentration of phosphate. Hence, despite the high pesticide pollution in the area, variation in nutrient-related stressors seems to be the dominant driver of the functional composition of aquatic macrofauna assembly in agricultural ditches.  相似文献   
18.
19.
20.
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