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   11485篇
  免费   550篇
  国内免费   40篇
耳鼻咽喉   179篇
儿科学   223篇
妇产科学   190篇
基础医学   1844篇
口腔科学   228篇
临床医学   919篇
内科学   2437篇
皮肤病学   217篇
神经病学   1061篇
特种医学   661篇
外国民族医学   1篇
外科学   1318篇
综合类   77篇
预防医学   557篇
眼科学   323篇
药学   1069篇
中国医学   65篇
肿瘤学   706篇
  2022年   63篇
  2021年   163篇
  2020年   96篇
  2019年   122篇
  2018年   155篇
  2017年   142篇
  2016年   190篇
  2015年   250篇
  2014年   309篇
  2013年   428篇
  2012年   603篇
  2011年   648篇
  2010年   392篇
  2009年   397篇
  2008年   650篇
  2007年   736篇
  2006年   666篇
  2005年   702篇
  2004年   693篇
  2003年   663篇
  2002年   644篇
  2001年   153篇
  2000年   147篇
  1999年   178篇
  1998年   147篇
  1997年   135篇
  1996年   107篇
  1995年   94篇
  1994年   98篇
  1993年   109篇
  1992年   100篇
  1991年   76篇
  1990年   80篇
  1989年   97篇
  1988年   86篇
  1987年   87篇
  1986年   85篇
  1985年   84篇
  1984年   66篇
  1983年   59篇
  1982年   66篇
  1981年   72篇
  1980年   47篇
  1979年   53篇
  1978年   45篇
  1977年   65篇
  1976年   44篇
  1975年   46篇
  1974年   40篇
  1973年   38篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Volume and profile of alcohol consumption among students and classmates as predictors of aggression and victimization: a multilevel analysis among Swiss adolescents

Objective:  

To test the effects of the volume of alcohol consumption and drinking patterns on alcohol-related aggression and victimization, both at the individual and class levels.  相似文献   
3.
A series of 5-hydroxy and 5-benzyloxy analogs of the antiarrhythmic and multidrug resistance (MDR) modulating drug propafenone was synthesized and the MDR-modulating activity of the compounds was evaluated using a daunomycin efflux assay system. The key step of the synthesis is the selective reduction of the double bond in 1 without cleavage of the benzyl group thus leading to the phenol 3 . Alkylation with epichlorohydrine followed by nucleophilic epoxide ring opening gave the benzylated target compounds 5a–d . Subsequent cleavage of the benzyl group gave the 5-hydroxy analogs 6a–d . Structure activity relationship studies showed, that the 5-hydroxy derivates 6a–d fit the log P/log potency correlation line previously established for a series of propafenone analogs. In contrast, all four 5-benzyloxy analogs 5a–d showed almost identical EC50 values, independent of their log P value.  相似文献   
4.
Development of the central nervous system (CNS) involves the transformation of a two-dimensional epithelial sheet of uniform ectodermal cells, the neuroectoderm, into a highly complex three-dimensional structure consisting of a huge variety of different neural cell types. Characteristic numbers of each cell type become arranged in reproducible spatial patterns, which is a prerequisite for the establishment of specific functional contacts. The fruitfly Drosophila is a suitable model to approach the mechanisms controlling the generation of cell diversity and pattern in the developing CNS, as it allows linking of gene function to individually identifiable cells. This review addresses aspects of the formation and specification of neural stem cells (neuroblasts) in Drosophila in the light of recent studies on their segmental diversification.  相似文献   
5.
In a single outbreak on the East coast of Madagascar, more than 500 people, 98 of whom died, were poisoned by the flesh of a shark, Carcharhinus amboinensis. From clinical symptoms it can be concluded that this poisoning is due to ciguatera toxins. It is the first case of a severe outbreak caused by a shark, and it is the first case with a mortality rate of 20%.  相似文献   
6.
7.
A mutation in the JH2 pseudokinase domain of the Janus kinase 2 gene (JAK2 V617F) has been described in chronic myeloproliferative disorders (MPD). We screened 79 acute myeloid leukemia (AML) cell lines and found five positive for JAK2 V617F (HEL, MB-02, MUTZ-8, SET-2, UKE-1), 4/5 with histories of MPD/MDS. While SET-2 expressed both mutant (mu) and wild-type (wt) JAK2, remaining positives carried homo-/hemizygous JAK2 mutations. Microsatellite analysis confirmed losses of heterozygosity (LOH) affecting the JAK2 region on chromosome 9p in MB-02, MUTZ-8 and UKE-1, but also in HEL, the only JAK2mu cell line lacking any reported MPD/MDS history. All five JAK2mu cell lines displayed cytogenetic hallmarks of MDS, namely losses of 5q or 7q, remarkably in 4/5 cases affecting both chromosomes. Our combined FISH and microsatellite analysis uncovered a novel mechanism to supplement mitotic recombination previously proposed to explain JAK2 LOH, namely chromosome deletion with/without selective JAK2mu amplification. Confirming the importance of the mutated JAK2 protein for growth and prevention of apoptosis, JAK2mu cell lines displayed higher sensitivities to JAK2 inhibition than JAK2wt cell lines. In summary, JAK2 V617F cell lines, derived from patients with history of MPD/MDS, represent novel research tools for elucidating the pathobiology of this JAK2 mutation.  相似文献   
8.
9.
Basic materials for contact lenses were obtained by radical copolymerization of linear α,ω-bis(methacryloyloxy)-terminated oligo- and poly(dimethylsiloxane)s, methyl methacrylate and 2,2,3,3,4,4,4-heptafuorobutyl methacrylate. Oxygen permeabilities, contact angles and ball indentation hardness were determined.  相似文献   
10.
Positron emission tomography (PET) using [(11)C]PK 11195, a ligand for peripheral benzodiazepine receptor binding sites, offers the opportunity to image activated microglia in vivo. This tool may therefore be used to display the occurrence of microglial activation in the course of neurodegeneration. A patient with the clinical diagnosis of corticobasal degeneration (CBD) and left-sided symptoms was studied using fluorodeoxyglucose (FDG) and [(11)C]PK 11195 PET. We found a marked right hemispheric hypometabolism and asymmetric microglial activation in corresponding areas of the basal ganglia and right temporal and parietal cortex. [(11)C]PK 11195 PET suggests involvement of microglial activation in the pathogenesis of CBD.  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