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   1516514篇
  免费   109706篇
  国内免费   1975篇
耳鼻咽喉   20220篇
儿科学   49851篇
妇产科学   43736篇
基础医学   226308篇
口腔科学   41435篇
临床医学   139318篇
内科学   294253篇
皮肤病学   32763篇
神经病学   120020篇
特种医学   56716篇
外国民族医学   304篇
外科学   218605篇
综合类   32356篇
现状与发展   4篇
一般理论   718篇
预防医学   122415篇
眼科学   34176篇
药学   110340篇
  10篇
中国医学   2699篇
肿瘤学   81948篇
  2018年   16534篇
  2017年   12581篇
  2016年   13870篇
  2015年   15976篇
  2014年   21960篇
  2013年   33811篇
  2012年   45424篇
  2011年   48228篇
  2010年   28419篇
  2009年   27045篇
  2008年   45230篇
  2007年   48562篇
  2006年   48119篇
  2005年   46830篇
  2004年   45182篇
  2003年   43207篇
  2002年   41665篇
  2001年   66724篇
  2000年   68031篇
  1999年   57361篇
  1998年   16051篇
  1997年   14608篇
  1996年   14848篇
  1995年   14039篇
  1994年   13111篇
  1993年   12274篇
  1992年   45141篇
  1991年   44690篇
  1990年   43298篇
  1989年   42044篇
  1988年   38877篇
  1987年   37959篇
  1986年   36251篇
  1985年   34352篇
  1984年   25984篇
  1983年   22689篇
  1982年   13481篇
  1981年   12142篇
  1979年   24725篇
  1978年   18088篇
  1977年   15135篇
  1976年   14029篇
  1975年   15228篇
  1974年   18498篇
  1973年   18291篇
  1972年   17202篇
  1971年   16124篇
  1970年   15274篇
  1969年   14291篇
  1968年   13462篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
HYPOTHESIS: Based on recent findings on the association between vascular risk factors and hippocampal atrophy, we hypothesized that hypertension and diabetes mellitus (DM) are associated with medial temporal lobe atrophy (MTA) in subjects without disability, independent of the severity of white matter hyperintensities. METHODS: In the Leukoaraiosis And DISability in the elderly (LADIS) study, we investigated the relationships between DM, hypertension, blood pressure and MTA in 582 subjects, stratified by white matter hyperintensity severity, using multinomial logistic regression. MTA was visually scored for the left and right medial temporal lobe (score 0-4), and meaned. RESULTS: Mean age was 73.5 years (sd 5.1), 54% was female. Of the subjects, 15% had DM, and 70% had a history of hypertension. The likelihood of having MTA score 3 was significantly higher in subjects with DM (OR 2.9; 95% CI: 1.1-7.8) compared with an MTA score of 0 (no atrophy). The odds ratio for MTA score 2 was not significantly increased (OR 1.8; CI: 0.9-4). Systolic and diastolic blood pressure and a history of hypertension were not associated with MTA. There was no interaction between DM and hypertension. Stratification on white matter hyperintensities (WMH) did not alter the associations. CONCLUSION: Our study strengthens the observation that MTA is associated with DM, independently of the amount of small vessel disease as reflected by WMH.  相似文献   
992.
Degranulating mast cells are increased in the airway smooth muscle (ASM) of asthmatics, where they may influence ASM function. The aim of the present study was to determine whether histamine and tryptase modulate ASM cell granulocyte-macrophage colony-stimulating factor (GM-CSF) and RANTES (regulated on activation, normal T-cell expressed and secreted) release and also to examine which receptors are involved in this release. Confluent, quiescent ASM cells from asthmatic and nonasthmatic donors were treated with histamine (1 microM-100 microM) with and without histamine receptor antagonist pre-treatment, or the protease-activated receptor (PAR)-2 agonists tryptase (0.5-5 nM) and SLIGKV (100 and 400 microM). The cells were then stimulated with interleukin (IL)-1beta and/or tumour necrosis factor (TNF)-alpha (10 ng.mL(-1)) or left unstimulated for 24 h. Release of GM-CSF and RANTES was determined by ELISA and prostaglandin (PG)E(2) measured by enzyme immunoassay. Neither histamine nor tryptase induced ASM GM-CSF or RANTES secretion. However, histamine increased IL-1beta-induced GM-CSF release and markedly reduced TNF-alpha-induced RANTES release by both asthmatic and nonasthmatic cells to a similar extent, but did not modulate PGE(2) release. All changes involved activation of the histamine H1 receptor as they were partially or fully blocked by chlorpheniramine, but not ranitidine. Tryptase, via its proteolytic activity, also potentiated GM-CSF, but not RANTES, release from asthmatic and nonasthmatic ASM cells induced by both cytokines. PAR-2 involvement in the tryptase potentiation was unlikely because SLIGKV had no effect. In conclusion, mast cells, through histamine and tryptase, may locally modulate airway smooth muscle-induced inflammation in asthma.  相似文献   
993.
Objectives: Heavy smokers are a segment of the smoking population who are at increased risk of smoking-related morbidity and least likely to achieve cessation. This study identifies the impact of heavy smoking on quality of life by gender and describes the subpopulation for improved targeting.Methods: South Australian representative population data (n = 3010) was used to compare the health-related quality of life status of male and female heavy smokers as assessed by the SF-36.  相似文献   
994.
In a prospective, randomized multicenter trial, 175 patients with abdominal aortic aneurysms were treated by conventional operation. Two types of polyester prostheses (Gelsoft Plus, Vascute Terumo Corp., Hamburg, Germany or Microvel, Boston Scientific, Ratingen, Germany) were selected randomly for implantation. Diameters ranged from 14 to 20 mm. The diameters of the grafts were measured by ultrasound postoperatively, as well as 6, 12, and 24 months after operation. Local and systemic complications were recorded. Dilation of the main body of the “Gelsoft plus” prosthesis was 19% within the first 12 months and 30% for the Microvel prosthesis. Extreme dilation was not observed. Thus, vascular prostheses must be chosen small enough and the dilation of 20–30% should be considered. The most frequent complication was incisional hernia (32%).  相似文献   
995.
996.
997.
998.
999.
1000.
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