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   105510篇
  免费   8920篇
  国内免费   4789篇
耳鼻咽喉   1332篇
儿科学   1366篇
妇产科学   1391篇
基础医学   13727篇
口腔科学   2046篇
临床医学   11010篇
内科学   16663篇
皮肤病学   1976篇
神经病学   5888篇
特种医学   5268篇
外国民族医学   21篇
外科学   12392篇
综合类   12344篇
现状与发展   28篇
一般理论   16篇
预防医学   6459篇
眼科学   3026篇
药学   10993篇
  68篇
中国医学   4189篇
肿瘤学   9016篇
  2024年   201篇
  2023年   1136篇
  2022年   2865篇
  2021年   4130篇
  2020年   2872篇
  2019年   2927篇
  2018年   3181篇
  2017年   2930篇
  2016年   3157篇
  2015年   4700篇
  2014年   5849篇
  2013年   5944篇
  2012年   8702篇
  2011年   9096篇
  2010年   5931篇
  2009年   5197篇
  2008年   6597篇
  2007年   6193篇
  2006年   5848篇
  2005年   5247篇
  2004年   4154篇
  2003年   4033篇
  2002年   3398篇
  2001年   2441篇
  2000年   2148篇
  1999年   1852篇
  1998年   1004篇
  1997年   898篇
  1996年   770篇
  1995年   687篇
  1994年   640篇
  1993年   445篇
  1992年   615篇
  1991年   528篇
  1990年   463篇
  1989年   428篇
  1988年   317篇
  1987年   293篇
  1986年   234篇
  1985年   164篇
  1984年   133篇
  1983年   87篇
  1982年   88篇
  1981年   71篇
  1980年   70篇
  1979年   72篇
  1978年   50篇
  1977年   48篇
  1973年   43篇
  1972年   50篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
43.
44.
OBJECTIVES: To assess the effectiveness and safety of additional bedtime H2‐receptor antagonists (H2RAs) in suppressing nocturnal gastric acid breakthrough (NAB) via a systematic review. METHODS: Eligible trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 2, 2004), MEDLINE (January 1966–June 2004), EMBASE (January 1980–June 2004) and CINAHL (January 1982–June 2004). Additional hand‐searching was conducted on the proceedings of correlated conferences, eight important Chinese journals and references of all included trials. All randomized controlled trials evaluating H2RAs for the control of NAB were eligible for inclusion. The systematic review was conducted using methods recommended by The Cochrane Collaboration. RESULTS: Only two randomized crossover studies, comprising 32 participants, met the inclusion criteria. Because the design, dosage and duration of the treatments were different between the studies, it was not possible to conduct meta‐analysis. There were no consistent conclusions found between the two included studies in evaluating H2RAs for the control of NAB. CONCLUSIONS: No implications for practice at this stage can be concluded. Appropriately designed large‐scale randomized controlled trials with long‐term follow up are needed to determine the effects of additional bedtime H2RAs in suppressing NAB.  相似文献   
45.
Laparoscopic surgery has several advantages over traditional surgery because it has been shown to be less invasive. The next logical step in the evolution of minimally invasive surgery may be to eliminate all abdominal incisions. The natural orifices provide a port of entry via the gastrointestinal tract to the peritoneal cavity. This approach would require the creation of a perforation, which is considered to be a major complication of endoscopy with significant morbidity and mortality. However, there are several recent studies that have described the technical feasibility and safety of a per‐oral transgastric approach to the peritoneal cavity using conventional endoscopes. Theoretically, this approach could reduce postoperative abdominal wall pain, wound infection, hernia formation, and adhesions. This article aims to summarize the current status of transgastric surgery, currently referred to as natural orifice transluminal endoscopic surgery (NOTES), and to address some of its future challenges.  相似文献   
46.
47.
48.
Mutations in the gene encoding 11beta-hydroxysteroid dehydrogenase type 2, HSD11B2, cause a rare monogenic juvenile hypertensive syndrome called apparent mineralocorticoid excess (AME). In AME, defective HSD11B2 enzyme activity results in overstimulation of the mineralocorticoid receptor (MR) by cortisol, causing sodium retention, hypokalemia, and salt-dependent hypertension. Here, we have studied whether genetic variations in HDS11B2 are implicated in essential hypertension in Japanese hypertensives and the general population. By sequencing the entire coding region and the promoter region of HDS11B2 in 953 Japanese hypertensives, we identified five missense mutations in 11 patients (L14F, n = 5; R74H, n = 1; R147H, n = 3; T156I, n = 1; R335H, n = 1) and one novel frameshift mutation (4884Gdel, n = 1) in a heterozygous state, in addition to 19 genetic variations. All genetic variations identified were rare, with minor allele frequencies less than 0.005. Four of 12 patients with the missense/frameshift mutations showed renal failure. Four missense mutations, L14F, R74H, R147H, and R335H, were successfully genotyped in the general population, with a sample size of 3,655 individuals (2,175 normotensives and 1,480 hypertensives). Mutations L14F, R74H, R147H, and R335H were identified in hypertensives (n = 6, 8, 3, and 0, respectively) and normotensives (n = 8, 12, 5, and 0, respectively) with a similar frequency, suggesting that these missense mutations may not strongly affect the etiology of essential hypertension. Since the allele frequency of all of the genetic variations identified in this study was rare, an association study was not conducted. Taken together, our results indicate that missense mutations in HSD11B2 do not substantially contribute to essential hypertension in Japanese.  相似文献   
49.
目的研究64层CT一次扫描同时完成心脏冠脉成像及心功能分析的可行性。方法96例患者均行MSCT心脏成像扫描和MR心脏检查,数据分别按照冠脉成像和心功能分析要求进行重建和后处理,评估。结果1271段冠脉血管中有约99%血管显示清晰,达到诊断要求;心功能分析数据左室舒张末期容积(LVEDV)、左室收缩末期容积(LVESV)、左室每搏输出量(LVSV)、左室射血分数(LVEF)、左室心肌容积(LVMV)与MR相关数据的相关系数分别为0.84、0.91、0.94、0.89、0.88。结论MSCT可以在一次扫描中完成冠脉成像和心功能数据采集,具有极高应用价值。  相似文献   
50.
管理人员职业紧张常模及转换表研制   总被引:1,自引:1,他引:0  
目的中高层管理人员、一般管理人员职业紧张常模、应用表、分级标准研究。方法采用职业紧张量表(OSI-R),对中高层管理人员263例、一般管理人员569例,共计832例常模样本进行研究。结果首先,采用OSI-R量表分别研制了中高层管理人员、一般管理人员职业紧张常模;其次,在常模的基础上,分别研制了常模样本粗分转换为T分表。职业紧张程度分级职业任务和紧张反应问卷中,T分≥70分者,为高度职业紧张、紧张反应;T分在60分至69分范围内者,为中度职业紧张、紧张反应;T分在40分至59分范围内者,为适度职业紧张和紧张反应;处于正常范围。T分低于40分者,为相对缺乏职业紧张和紧张反应。在应对资源问卷中,T分低于30分者,表明高度缺乏应对资源;T分在30分至39分范围内者,表明中度缺乏应对资源;T分在40分至59分范围之间者,具有适度的应对资源,属于正常范围;T分≥60分者,表明有很强的应对资源。结论将职业紧张的模式结合中高层管理人员、一般管理人员职业紧张常模及应用表,分别针对不同个体主要紧张源、紧张反应、应对资源,采取有针对性的干预(组织、个体)措施,以降低中高层管理人员、一般管理人员职业紧张程度,保护和促进工作能力是职业卫生领域面临的重要任务之一。  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