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   71615篇
  免费   5007篇
  国内免费   200篇
耳鼻咽喉   529篇
儿科学   2094篇
妇产科学   1166篇
基础医学   9834篇
口腔科学   1505篇
临床医学   7522篇
内科学   15223篇
皮肤病学   981篇
神经病学   6824篇
特种医学   2228篇
外国民族医学   1篇
外科学   10043篇
综合类   878篇
一般理论   72篇
预防医学   6399篇
眼科学   1737篇
药学   4905篇
  1篇
中国医学   80篇
肿瘤学   4800篇
  2023年   376篇
  2022年   520篇
  2021年   1396篇
  2020年   839篇
  2019年   1365篇
  2018年   1659篇
  2017年   1237篇
  2016年   1356篇
  2015年   1582篇
  2014年   2367篇
  2013年   3210篇
  2012年   5236篇
  2011年   5368篇
  2010年   3001篇
  2009年   2666篇
  2008年   4873篇
  2007年   5332篇
  2006年   5237篇
  2005年   4971篇
  2004年   4767篇
  2003年   4310篇
  2002年   4206篇
  2001年   576篇
  2000年   413篇
  1999年   637篇
  1998年   899篇
  1997年   755篇
  1996年   634篇
  1995年   605篇
  1994年   490篇
  1993年   464篇
  1992年   348篇
  1991年   304篇
  1990年   256篇
  1989年   246篇
  1988年   261篇
  1987年   213篇
  1986年   231篇
  1985年   240篇
  1984年   308篇
  1983年   324篇
  1982年   384篇
  1981年   369篇
  1980年   343篇
  1979年   197篇
  1978年   239篇
  1977年   191篇
  1976年   133篇
  1975年   102篇
  1974年   105篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
971.
972.
This was a web-based survey of members of the British Society for Gynaecological Endoscopy to establish what features of integrated theatres are considered desirable to surgeons. A secondary aim was to assess if there are differences in preference between those surgeons who use these theatres regularly and those who have never used them. Respondents were asked to rank a list of 14 features of integrated theatres in terms of desirability with 1 being most desirable and 14 being least desirable. They were separately asked to rate each feature according to importance. The main outcome measures were the ranking and rating of each feature. In all 121/639 (18.9 %) surgeons responded, 83 (68.6 %) were male and 38 (31.4 %) were female. Ninety-two (76.0 %) were consultants and 29 (24.0 %) junior doctors. Sixty-six (54.5 %) had never used an integrated theatre, 24 (19.8 %) occasionally (one to six times/year) and 31 (25.6 %) regularly (greater than six times/year). There was significant regional variation in the usage of integrated theatres with the more affluent parts of the country (London and south of England) having a higher usage rate than more deprived areas (north of England). Some features of integrated theatres are consistently rated more highly than others. There were differences in preference between surgeons who use integrated theatres regularly and those who do not. It may be worth consulting with surgeons with experience of both purchasing and using these theatres in order to get the most appropriate system both in terms of cost and ergonomics.  相似文献   
973.
974.
Ectopic Mer expression promotes pro-survival signaling and contributes to leukemogenesis and chemoresistance in childhood acute lymphoblastic leukemia (ALL). Consequently, Mer kinase inhibitors may promote leukemic cell death and further act as chemosensitizers increasing efficacy and reducing toxicities of current ALL regimens. We have applied a structure-based design approach to discover novel small molecule Mer kinase inhibitors. Several pyrazolopyrimidine derivatives effectively inhibit Mer kinase activity at sub-nanomolar concentrations. Furthermore, the lead compound shows a promising selectivity profile against a panel of 72 kinases and has excellent pharmacokinetic properties. We also describe the crystal structure of the complex between the lead compound and Mer, opening new opportunities for further optimization and new template design.  相似文献   
975.
976.
Allergic rhinitis (AR) with or without conjunctivitis (AR/C) is associated with a significant health and economic burden, and is often accompanied by asthma. Pharmacotherapies are the mainstay treatment options for AR and asthma, but guidelines also recommend allergy immunotherapy (AIT). Unlike pharmacotherapies, AIT has the ability to modify the underlying immunologic mechanisms of AR and asthma with the potential for long-term benefits after treatment is discontinued. Immunotherapy may also prevent progression of AR/C to asthma. Sublingual immunotherapy (SLIT)-tablets are a self-administered alternative to subcutaneous immunotherapy that provide the benefits of AIT without the cost and inconvenience of frequent office visits or the discomfort of injections. SLIT-tablets are also an option that can be utilized by primary care clinicians. Pharmacotherapies are generally effective in mild disease although a number of patients remain uncontrolled. SLIT-tablets have proven efficacy for AR in adults, children, and poly-sensitized allergic patients. Indirect comparisons indicate that SLIT-tablets have superior or comparable efficacy compared with traditional pharmacotherapies for seasonal AR, and superior efficacy for perennial AR. House dust mite (HDM) SLIT-tablets have also demonstrated clinically relevant benefits for asthma, with significant observed reductions in daily inhaled corticosteroid use, risk of asthma exacerbations, and asthma symptoms. SLIT-tablets are well tolerated, with minimal risk of systemic allergic reactions. The most common treatment-related adverse events are oral site reactions such as oral pruritus and throat irritation. Based on the favorable efficacy and safety profile, as well as the convenience of at-home oral administration and disease-modifying effects, SLIT-tablets should be considered as an alternative or add-on treatment to pharmacotherapy for AR/C, and as an add-on treatment for HDM allergic asthma.  相似文献   
977.
A 56-year-old woman developed progressive headache, mental status changes, and diplopia after trauma. She was diagnosed with alternating skew deviation caused by intracranial hypotension. This is the first case of alternating skew deviation reported from intracranial hypotension and perhaps a differential pressure between intracranial and intraspinal spaces plays a role in the development of these findings.  相似文献   
978.
979.
Background: Nitrate is a widespread groundwater contaminant and a leading cause of drinking water quality violations in California. Associations between nitrate exposure and select adverse birth outcomes have been suggested, but few studies have examined gestational exposures to nitrate and risk of preterm birth (before 37 wk gestation).Objective: We investigated the association between elevated nitrate in drinking water and spontaneous preterm birth through a within-mother retrospective cohort study of births in California.Methods: We acquired over 6 million birth certificate records linked with Office of Statewide Health Planning and Development hospital discharge data for California births from 2000–2011. We used public water system monitoring records to estimate nitrate concentrations in drinking water for each woman’s residence during gestation. After exclusions, we constructed a sample of 1,443,318 consecutive sibling births in order to conduct a within-mother analysis. We used separate conditional logistic regression models to estimate the odds of preterm birth at 20–31 and 32–36 wk, respectively, among women whose nitrate exposure changed between consecutive pregnancies.Results: Spontaneous preterm birth at 20–31 wk was increased in association with tap water nitrate concentrations during pregnancy of 5 to <10mg/L [odds ratio (OR)=1.47; 95% confidence interval (CI): 1.29, 1.67] and 10mg/L (OR=2.52; 95% CI: 1.49, 4.26) compared with <5mg/L (as nitrogen). Corresponding estimates for spontaneous preterm birth at 32–36 wk were positive but close to the null for 5 to <10mg/L nitrate (OR=1.08; 95% CI: 1.02, 1.15) and for 10mg/L nitrate (OR=1.05; 95% CI: 0.85, 1.31) vs. <5mg/L nitrate. Our findings were similar in several secondary and sensitivity analyses, including in a conventional individual-level design.Discussion: The results suggest that nitrate in drinking water is associated with increased odds of spontaneous preterm birth. Notably, we estimated modestly increased odds associated with tap water nitrate concentrations of 5 to <10mg/L (below the federal drinking water standard of 10mg/L) relative to <5mg/L. https://doi.org/10.1289/EHP8205  相似文献   
980.
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