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   1018101篇
  免费   82465篇
  国内免费   6540篇
耳鼻咽喉   14720篇
儿科学   28046篇
妇产科学   29194篇
基础医学   146399篇
口腔科学   29498篇
临床医学   89931篇
内科学   191679篇
皮肤病学   19786篇
神经病学   79943篇
特种医学   41208篇
外国民族医学   193篇
外科学   156447篇
综合类   37735篇
现状与发展   16篇
一般理论   303篇
预防医学   78042篇
眼科学   24340篇
药学   79223篇
  51篇
中国医学   5069篇
肿瘤学   55283篇
  2021年   8519篇
  2018年   10460篇
  2016年   9324篇
  2015年   11497篇
  2014年   15747篇
  2013年   21949篇
  2012年   30143篇
  2011年   31748篇
  2010年   19202篇
  2009年   17436篇
  2008年   28614篇
  2007年   30918篇
  2006年   30433篇
  2005年   29714篇
  2004年   28322篇
  2003年   27381篇
  2002年   26039篇
  2001年   42745篇
  2000年   43198篇
  1999年   36643篇
  1998年   11351篇
  1997年   10272篇
  1996年   9630篇
  1995年   9172篇
  1994年   8678篇
  1992年   30140篇
  1991年   29613篇
  1990年   28856篇
  1989年   27921篇
  1988年   26309篇
  1987年   25818篇
  1986年   24563篇
  1985年   23784篇
  1984年   18253篇
  1983年   15622篇
  1982年   9760篇
  1981年   8936篇
  1979年   18450篇
  1978年   13186篇
  1977年   11073篇
  1976年   10163篇
  1975年   11245篇
  1974年   13875篇
  1973年   13421篇
  1972年   12779篇
  1971年   11840篇
  1970年   11265篇
  1969年   10941篇
  1968年   9859篇
  1967年   9064篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
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   
23.
24.
25.
26.
27.
28.
29.
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   
30.
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   
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