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   150585篇
  免费   30956篇
  国内免费   2399篇
耳鼻咽喉   5162篇
儿科学   5403篇
妇产科学   2414篇
基础医学   3088篇
口腔科学   1523篇
临床医学   26590篇
内科学   47093篇
皮肤病学   7485篇
神经病学   14739篇
特种医学   6322篇
外科学   40813篇
综合类   251篇
现状与发展   72篇
一般理论   2篇
预防医学   7093篇
眼科学   3319篇
药学   903篇
中国医学   6篇
肿瘤学   11662篇
  2024年   686篇
  2023年   4790篇
  2022年   1195篇
  2021年   3088篇
  2020年   6019篇
  2019年   2153篇
  2018年   7375篇
  2017年   7331篇
  2016年   8411篇
  2015年   8392篇
  2014年   15467篇
  2013年   15581篇
  2012年   5415篇
  2011年   5434篇
  2010年   10328篇
  2009年   14220篇
  2008年   5743篇
  2007年   3996篇
  2006年   6439篇
  2005年   3715篇
  2004年   3005篇
  2003年   1956篇
  2002年   2048篇
  2001年   3771篇
  2000年   2985篇
  1999年   3192篇
  1998年   3634篇
  1997年   3453篇
  1996年   3353篇
  1995年   3205篇
  1994年   1936篇
  1993年   1558篇
  1992年   1370篇
  1991年   1404篇
  1990年   1050篇
  1989年   1176篇
  1988年   1010篇
  1987年   850篇
  1986年   881篇
  1985年   712篇
  1984年   547篇
  1983年   523篇
  1982年   515篇
  1981年   403篇
  1980年   359篇
  1979年   306篇
  1978年   330篇
  1977年   398篇
  1975年   278篇
  1972年   303篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The efficacy and safety of ketoprofen and paracetamol were compared for the treatment of acute migraine in a randomized, double-blind study of 64 patients. Thirty-four patients received ketoprofen 100 mg intramuscularly, and 30 patients received paracetamol 500 mg intramuscularly. Partial or complete relief of pain and other symptoms was achieved 15 to 20 minutes after administration in the ketoprofen group and within 35 minutes in the paracetamol group. Complete relief of pain was achieved within 30 to 40 minutes after ketoprofen in 28 patients (82.5%) compared to 5 patients (17.5%) in the paracetamol group. Six of the patients treated with ketoprofen needed a second dose for complete relief of pain during the 4-hour follow-up period. Side effects were rare and minimal. Our findings suggest that ketoprofen produced statistically significant benefit in the treatment of acute migraine.  相似文献   
92.
93.
94.
95.
96.
97.
Human adult endothelial cells were enzymatically harvested from adipose tissue. Cell viability was established by Trypan blue exclusion and transmission and scanning electron microscopy. Endothelial cells were identified by immunocytochemical investigation at light microscopy, transmission electron microscopy, and scanning electron microscopy. Isolated cells were positive for actin and vimentin, negative for desmin. Factor VIII RA was mainly expressed at cell surface and occasionally disclosed in the cytoplasm. Reactivity for UEA I and J15 was weak or undetectable. Human endothelial cells were seeded and left to adhere for one hour onto different nonvascular substrates (glass, poly-l-lysine, formvar-carbon, fibronectin, Teflon). Scanning electron microscopy defined surface features, suggesting tenacious cell adhesion on the substrate. Different vascular substrates were tested (preclotted Dacron, albumin Dacron, Hemashield Dacron, Gelseal Dacron, ePTFE, fibronectin-ePTFE). Commercially available coated grafts showed qualitative and quantitative differences in cell adhesion. In particular, Gelseal Dacron provided the best quantitative results, even though a wide variability was observed. In contrast, fibronectin-coated ePTFE gave more reliable results and high spreading efficiency. In the short term, coated grafts do not seem to offer greater advantages than fibronectin-coated ePTFE. However, specific incubation times for each coated graft should be selected and the long-term approach (graft culture) should also be attempted.  相似文献   
98.
99.
100.
BACKGROUND: Endothelin, a peptide with strong vasoconstrictive and mitogenic properties, has been found to increase after cardiac transplantation. We therefore assessed the association between its precursor peptide, big endothelin-1, and intimal hyperplasia and coronary flow reserve after heart transplantation. METHODS: Thirty-five patients without hemodynamically significant coronary artery disease after heart transplantation were investigated: Average peak flow velocity in the left anterior descending artery (LAD) was assessed by intracoronary Doppler at baseline as well as after injection of adenosine; coronary flow reserve was calculated as a ratio of both and was corrected for patient age and baseline average peak flow velocity. Lumen, intima + media and total vessel area were measured by intracoronary ultrasound. The plasma concentration of big endothelin-1 in venous blood was determined by radioimmunoassay. RESULTS: Patients with elevated big endothelin-1 levels (>2 fmol/ml) tended to have a decreased corrected coronary flow reserve (2.60 +/- 0.9 vs 3.21 +/- 1.0, p = 0.078). They also had a significantly larger intima + media area (5.82 +/- 2.9 vs 2.37 +/- 2.9 mm(2), p = 0.004) and total vessel area (18.36 +/- 5.8 vs 12.81 +/- 4.8 mm(2), p = 0.012) than those with normal plasma concentrations. CONCLUSIONS: Our study suggests an association between elevated big endothelin-1 plasma levels and the development of intimal hyperplasia and reduction of coronary flow reserve after cardiac transplantation.  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