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   2228602篇
  免费   165804篇
  国内免费   4334篇
耳鼻咽喉   29797篇
儿科学   68649篇
妇产科学   60333篇
基础医学   314950篇
口腔科学   61903篇
临床医学   195859篇
内科学   441850篇
皮肤病学   48884篇
神经病学   181602篇
特种医学   86305篇
外国民族医学   536篇
外科学   346029篇
综合类   47374篇
现状与发展   4篇
一般理论   678篇
预防医学   166740篇
眼科学   50029篇
药学   161802篇
  4篇
中国医学   4847篇
肿瘤学   130565篇
  2019年   15966篇
  2018年   32249篇
  2017年   25112篇
  2016年   28654篇
  2015年   22736篇
  2014年   31499篇
  2013年   46773篇
  2012年   65736篇
  2011年   74963篇
  2010年   46024篇
  2009年   42640篇
  2008年   71429篇
  2007年   76846篇
  2006年   67737篇
  2005年   67152篇
  2004年   64766篇
  2003年   63088篇
  2002年   60354篇
  2001年   114540篇
  2000年   117659篇
  1999年   97513篇
  1998年   25641篇
  1997年   23010篇
  1996年   23056篇
  1995年   21810篇
  1994年   19926篇
  1993年   18582篇
  1992年   74061篇
  1991年   70874篇
  1990年   68176篇
  1989年   65708篇
  1988年   60177篇
  1987年   58749篇
  1986年   54683篇
  1985年   52400篇
  1984年   38741篇
  1983年   32689篇
  1982年   18704篇
  1981年   16411篇
  1979年   34217篇
  1978年   23571篇
  1977年   19831篇
  1976年   18098篇
  1975年   19017篇
  1974年   23089篇
  1973年   22073篇
  1972年   20769篇
  1971年   19213篇
  1970年   18334篇
  1969年   17113篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
31.
32.
33.
Pharmaceutical Chemistry Journal - An HPLC-MS method for simultaneous quantitative determination of a novel gestagenic pharmaceutical and two of its metabolites in rat and rabbit blood sera was...  相似文献   
34.
Aims: In neuropsychological evaluations, it is often difficult to ascertain whether poor performance on measures of validity is due to poor effort or malingering, or whether there is genuine cognitive impairment. Dunham and Denney created an algorithm to assess this question using the Medical Symptom Validity Test (MSVT). We assessed the ability of their algorithm to detect poor validity versus probable impairment, and concordance of failure on the MSVT with other freestanding tests of performance validity.

Methods: Two previously published datasets (n?=?153 and n?=?641, respectively) from outpatient neuropsychological evaluations were used to test Dunham and Denney’s algorithm, and to assess concordance of failure rates with the Test of Memory Malingering and the forced choice measure of the California Verbal Learning Test, two commonly used performance validity tests.

Results: In both datasets, none of the four cutoff scores for failure on the MSVT (70%, 75%, 80%, or 85%) identified a poor validity group with proportionally aligned failure rates on other freestanding measures of performance validity. Additionally, the protocols with probable impairment did not differ from those with poor validity on cognitive measures.

Conclusions: Despite what appeared to be a promising approach to evaluating failure on the easy MSVT subtests when clinical data are unavailable (as recommended in the advanced interpretation program, or advanced interpretation [AI], of the MSVT), the current findings indicate the AI remains the gold standard for doing so. Future research should build on this effort to address shortcomings in measures of effort in neuropsychological evaluations.  相似文献   

35.
36.
37.
38.

Objectives

Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.

Methods

Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.

Results

A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.

Conclusions

Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight.  相似文献   
39.
Metabolism describes the series of chemical reactions that are concerned with the provision of energy to biological systems. They may be divided into reactions involved in energy yield (catabolism: demand exceeds supply), and energy storage (anabolism: supply exceeds demand). Regulation of these pathways is critical for homeostasis, and derangements in metabolism are seen in a wide variety of pathological processes. Understanding metabolism is key to the treatment of many diseases, notably diabetes, as well as underpinning clinical nutritional support.  相似文献   
40.
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