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   10994篇
  免费   778篇
  国内免费   55篇
耳鼻咽喉   94篇
儿科学   492篇
妇产科学   162篇
基础医学   1538篇
口腔科学   188篇
临床医学   983篇
内科学   2099篇
皮肤病学   217篇
神经病学   1137篇
特种医学   806篇
外国民族医学   5篇
外科学   1537篇
综合类   91篇
一般理论   6篇
预防医学   535篇
眼科学   239篇
药学   987篇
中国医学   6篇
肿瘤学   705篇
  2021年   108篇
  2019年   102篇
  2018年   154篇
  2017年   104篇
  2016年   164篇
  2015年   195篇
  2014年   205篇
  2013年   322篇
  2012年   395篇
  2011年   449篇
  2010年   283篇
  2009年   252篇
  2008年   378篇
  2007年   420篇
  2006年   429篇
  2005年   378篇
  2004年   434篇
  2003年   403篇
  2002年   339篇
  2001年   348篇
  2000年   349篇
  1999年   280篇
  1998年   219篇
  1997年   206篇
  1996年   205篇
  1995年   166篇
  1994年   135篇
  1993年   153篇
  1992年   237篇
  1991年   238篇
  1990年   225篇
  1989年   293篇
  1988年   256篇
  1987年   243篇
  1986年   230篇
  1985年   252篇
  1984年   155篇
  1983年   121篇
  1982年   116篇
  1981年   98篇
  1980年   117篇
  1979年   151篇
  1978年   105篇
  1977年   96篇
  1976年   127篇
  1975年   123篇
  1974年   94篇
  1973年   75篇
  1971年   89篇
  1970年   83篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
41.
In an animal model of drug idiosyncrasy, rats cotreated with nonhepatotoxic doses of lipopolysaccharide (LPS) and ranitidine (RAN) develop hepatocellular injury, whereas rats treated with LPS and famotidine (FAM) do not. The coagulation system and neutrophils (PMNs) are requisite mediators of LPS/RAN-induced liver injury. We tested the hypothesis that unique gene expression in LPS/RAN-treated rats requires coagulation system activation and that these changes are absent in rats given LPS and FAM. Rats were treated with a nonhepatotoxic dose of LPS (44.4 x 10(6) endotoxin units/kg i.v.) or its vehicle, and then 1 h later, they were treated with heparin (3000 U/kg) or its vehicle. One hour thereafter, they were given RAN (30 mg/kg), FAM (6 mg/kg, a pharmacologically equiefficacious dose, or 28.8 mg/kg, an equimolar dose), or vehicle (i.v.). They were killed 2 or 6 h after drug treatment for evaluation of hepatotoxicity, coagulation system activation, and liver gene expression (2 h only). Statistical filtering of gene array results and real-time polymerase chain reaction identified groups of genes expressed in LPS/RAN-treated rats but not LPS/FAM-treated rats that were either changed or unchanged by heparin administration. For example, LPS/RAN-induced mRNA expression of the inflammatory mediators interleukin-6, cyclooxygenase-2, and macrophage inflammatory protein-2 (MIP-2) was reduced by anticoagulation. Enhancement of serum MIP-2 and plasminogen activator inhibitor-1 concentrations in LPS/RAN-treated rats was prevented by anticoagulation. The results suggest cross-talk between hemostasis-induced gene expression and inflammation (e.g., PMN function) in the genesis of hepatocellular injury in LPS/RAN-treated rats. In contrast, neither the expression of such genes nor hepatocellular necrosis occurred in rats treated with LPS/FAM.  相似文献   
42.
Tang SJ  Raman S  Reber HA  Bedford R  Roth BE 《Endoscopy》2002,34(12):1028-1029
  相似文献   
43.
44.
45.
46.
Bode RK, Heinemann AW, Butt Z, Stallings J, Taylor C, Rowe M, Roth EJ. Development and validation of participation and positive psychologic function measures for stroke survivors.

Objective

To evaluate the reliability and validity of Neurologic Quality of Life (NeuroQOL) item banks that assess quality-of-life (QOL) domains not typically included in poststroke measures.

Design

Secondary analysis of item responses to selected NeuroQOL domains.

Setting

Community.

Participants

Community-dwelling stroke survivors (n=111) who were at least 12 months poststroke.

Interventions

Not applicable.

Main Outcome Measures

Five measures developed for 3 NeuroQoL domains: ability to participate in social activities, satisfaction with participation in social activities, and positive psychologic function.

Results

A single bank was developed for the positive psychologic function domain, but 2 banks each were developed for the ability-to-participate and satisfaction-with-participation domains. The resulting item banks showed good psychometric properties and external construct validity with correlations with the legacy instruments, ranging from .53 to .71. Using these measures, stroke survivors in this sample reported an overall high level of QOL.

Conclusions

The NeuroQoL-derived measures are promising and valid methods for assessing aspects of QOL not typically measured in this population.  相似文献   
47.
We analyzed preoperative patient characteristics and postoperative functional outcomes to identify the most predictive preoperative characteristics of postoperative functional outcome for Cruciate Retaining (CR) TKA. In a prospective, multicenter study, 307 knees with minimum 2-year follow-up were first divided into groups based on 2-year functional performance. Logistic regression then determined SF-36 General Health Score (GHS) to be the most predictive preoperative patient characteristic. Subsequently, a second analysis was performed using preoperative SF-36 GHS to stratify patients into groups. Statistical significance was achieved in both analyses by gender, BMI and hypertension. Statistical significance was achieved in a single analysis by age, preoperative narcotic use, preoperative metabolic medication usage, preoperative pulmonary disease and preoperative use of medication for anxiety or depression.  相似文献   
48.
Cerebrospinal fluid (CSF)/plasma ratios of 1 to 30% were obtained in rhesus monkeys for the 3'-azido- and 2',3'-dideoxy-analogs of thymidine, deoxycytidine and deoxyuridine. Penetration of thymidine and deoxyuridine analogs was much greater than for deoxycytidine analogs. Octanol/buffer partition coefficients varied more than 30-fold, but did not correlate with CSF entry. Plasma protein binding was insignificant for all compounds. The presence or absence of the azido group at position 3' did not appear to influence the extent of CSF penetration. Although we do not fully understand the mechanistic basis for the penetration of these nucleosides into the CSF, it is apparent that the structural specificity is related more closely to the nucleobase than the sugar. Based upon elimination rates from the CSF after direct intrathecal injection, the differences in net penetration are determined by influx rather than efflux processes.  相似文献   
49.
50.
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