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   11600篇
  免费   943篇
  国内免费   143篇
耳鼻咽喉   197篇
儿科学   191篇
妇产科学   165篇
基础医学   2047篇
口腔科学   112篇
临床医学   1056篇
内科学   2216篇
皮肤病学   693篇
神经病学   850篇
特种医学   797篇
外科学   1189篇
综合类   37篇
现状与发展   1篇
一般理论   2篇
预防医学   492篇
眼科学   302篇
药学   1147篇
中国医学   191篇
肿瘤学   1001篇
  2024年   5篇
  2023年   66篇
  2022年   382篇
  2021年   569篇
  2020年   296篇
  2019年   378篇
  2018年   412篇
  2017年   381篇
  2016年   582篇
  2015年   752篇
  2014年   854篇
  2013年   896篇
  2012年   1264篇
  2011年   1161篇
  2010年   701篇
  2009年   560篇
  2008年   690篇
  2007年   626篇
  2006年   497篇
  2005年   472篇
  2004年   349篇
  2003年   296篇
  2002年   231篇
  2001年   45篇
  2000年   39篇
  1999年   25篇
  1998年   29篇
  1997年   20篇
  1996年   13篇
  1995年   15篇
  1994年   8篇
  1993年   7篇
  1992年   5篇
  1991年   11篇
  1990年   8篇
  1989年   9篇
  1988年   6篇
  1987年   3篇
  1986年   1篇
  1985年   7篇
  1984年   5篇
  1983年   1篇
  1981年   1篇
  1980年   2篇
  1979年   4篇
  1976年   1篇
  1962年   1篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
ObjectivesThis study examines receipt of formal sex education as a potential mechanism that may explain the observed associations between disability status and contraceptive use among young women with disabilities.Study designUsing the 2011?2017 National Survey of Family Growth, we analyzed data from 2861 women aged 18 to 24 years, who experienced voluntary first sexual intercourse with a male partner. Women whose first intercourse was involuntary (7% of all women reporting sexual intercourse) were excluded from the analytic sample. Mediation analysis was used to estimate the indirect effect of receipt of formal sex education before first sexual intercourse on the association between disability status and contraceptive use at first intercourse.ResultsCompared to nondisabled women, women with cognitive disabilities were less likely to report receipt of instruction in each of 6 discrete formal sex education topics and received instruction on a fewer number of topics overall (B = ?0.286, 95% CI = ?0.426 to ?0.147), prior to first voluntary intercourse. In turn, the greater number of topics received predicted an increased likelihood of contraceptive use at first voluntary intercourse among these women (B = 0.188, 95% CI = 0.055?0.321). No significant association between noncognitive disabilities and receipt of formal sex education or contraceptive use at first intercourse was observed.ConclusionsGiven the positive association between formal sex education and contraceptive use among young adult women with and without disabilities, ongoing efforts to increase access to formal sex education are needed. Special attention is needed for those women with cognitive disabilities.  相似文献   
62.
Three 1,2-benzothiazine derivatives were synthesized, and their analgesic/anti-inflammatory efficacy and their effects on gastric irritation were evaluated. Among the three compounds, 39 exhibited the most potent analgesic action, but the effect was weaker than that of piroxicam. Nonetheless, the compound showed 4 times more potent analgesic action with less gastric damage than did ibuprofen. These compounds did not show anti-inflammatory effect at an oral dose of 5 mg/kg.  相似文献   
63.
The extracts of sixty Korean plants were evaluated for their biological activities such as antitumor activities against Sarcoma 180, Leukemia SN-36 and Ehrlich ascites carcinoma, antimicrobial activities and behavioral observation in mice. The results are tabulated.  相似文献   
64.
Vitamin H (biotin) was incorporated into a hydrophobically modified polysaccharide, pullulan acetate (PA), in order to improve the cancer-targeting activity and internalization of self-assembled nanoparticles. The biotinylated pullulan acetate (BPA) nanoparticles were prepared by a diafiltration method and the mean diameter was approximately 100 nm. Three samples of biotinylated pullulan acetate (BPA), comprising 7 (BPA 1), 20 (BPA 2), and 39 (BPA 3) vitamin H groups per 100 anhydroglucose units of PA, were synthesized. The critical aggregation concentrations (CAC) of the BPA nanoparticles in distilled water were 3.1 x 10(-3), 4.3 x 10(-3) and 6.8 x 10(-3) mg/ml for BPA 1, BPA 2, and BPA 3, respectively. Adriamycin (ADR) was loaded into the BPA nanoparticles as a model drug. The loading efficiencies and ADR content in the BPA nanoparticles decreased with increasing vitamin H content due to a lower hydrophobicity. The RITC-labeled BPA nanoparticles exhibited very strong adsorption to the HepG2 cells, while the RITC-labeled PA nanoparticles did not show any significant interaction. The degree of the interaction increased with increasing vitamin H content. Confocal laser microscopy also revealed that internalization of the BPA nanoparticles into the cancer cells depended on the vitamin H content.  相似文献   
65.
66.
67.
68.
69.
Targeted application of next-generation sequencing (NGS) technology allows detection of specific mutations that can provide treatment opportunities for cancer patients. We evaluated the applicability of the Ion AmpliSeq Cancer Hotspot Panel V2 (CHV2) using formalin-fixed, paraffin-embedded (FFPE) tissue of clinical specimens.Thirty-five FFPE tumour samples with known mutational status were collected from four different hospitals and sequenced with CHV2 using an Ion Chef System and Ion S5 XL system. Out of 35 cases, seven were sequenced with Oncomine focus Assay Panel for comparison. For the limit of detection test, we used an FFPE reference standard, a cell line that included an engineered 50% EGFR T790?M in an RKO cell line background. Coverage analysis results including number of mapped reads, on target percent, mean depth, and uniformity were not different according to hospitals. Sensitivity for mutation detection down to 3% was demonstrated. NGS results showed 100% concordance with the results from single molecular pathology tests Assay in 30 cases with 24 known positive mutations and 14 known negative mutations, and another NGS panel of the Oncomine focus in seven cases.The CHV2 NGS test for solid tumours using Ion chef system and S5 XL system in clinical molecular pathology laboratories for analysis of solid tumours could be routinely used and could replace some single molecular pathology tests after a stringent and thorough validation process.  相似文献   
70.
Abstract

IgG consists of four subclasses: IgG1, IgG2, IgG3, and IgG4. Changes in the serum concentration of each subclass reflect different clinical situations, and quantification of each subclass is important to assess patients’ clinical states. Herein, we evaluated the analytical performance of the SPAPLUS turbidimetric analyzer (The Binding Site, Birmingham, UK) for IgG subclass. Precision, linearity, comparison with the BNII system (Siemens Healthineers, Erlangen, Germany), and reference interval were assessed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The repeatability and within-laboratory precision were within 5% for all IgG subclasses. The coefficient of determination (R2) was higher than 0.99 for the analytical measurement range in all IgG subclasses. Comparison between SPAPLUS and BNII revealed significant differences in IgG1, IgG3, and IgG4 (p?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