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   1859篇
  免费   74篇
  国内免费   16篇
耳鼻咽喉   23篇
儿科学   28篇
妇产科学   82篇
基础医学   181篇
口腔科学   131篇
临床医学   124篇
内科学   398篇
皮肤病学   25篇
神经病学   174篇
特种医学   119篇
外科学   279篇
综合类   14篇
一般理论   2篇
预防医学   148篇
眼科学   15篇
药学   135篇
中国医学   18篇
肿瘤学   53篇
  2023年   6篇
  2022年   39篇
  2021年   52篇
  2020年   23篇
  2019年   48篇
  2018年   50篇
  2017年   27篇
  2016年   46篇
  2015年   66篇
  2014年   97篇
  2013年   93篇
  2012年   149篇
  2011年   164篇
  2010年   95篇
  2009年   58篇
  2008年   98篇
  2007年   117篇
  2006年   86篇
  2005年   92篇
  2004年   88篇
  2003年   67篇
  2002年   66篇
  2001年   19篇
  2000年   18篇
  1999年   17篇
  1998年   13篇
  1997年   9篇
  1996年   8篇
  1995年   6篇
  1994年   7篇
  1992年   8篇
  1991年   15篇
  1990年   6篇
  1989年   17篇
  1988年   10篇
  1987年   15篇
  1986年   10篇
  1985年   10篇
  1984年   17篇
  1983年   10篇
  1982年   15篇
  1981年   5篇
  1980年   11篇
  1978年   7篇
  1976年   10篇
  1975年   7篇
  1974年   10篇
  1973年   7篇
  1970年   4篇
  1967年   4篇
排序方式: 共有1949条查询结果,搜索用时 15 毫秒
21.
The aim of this study was to assess the levels of oxidative, inflammatory, and fibrinolytic biomarkers as well as DNA strand breakage in hypercholesterolemic subjects. Fasting glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, uric acid, total protein, albumin, apolipoprotein (Apo) A, Apo B, advanced oxidation protein products (AOPP), increased ischemia-modified albumin (IMA), ―SH, NOx, IL-6, and D-dimer levels were assessed, and DNA strand breakage was evaluated using comet assay in 38 patients with hypercholesterolemia and 20 healthy controls. Total cholesterol, triglycerides, LDL cholesterol, Apo A, Apo B, AOPP, IMA, IL-6, and D-dimer concentrations were significantly higher in subjects with hypercholesterolemia. However, NOx and plasma ―SH group concentrations were lower in hypercholesterolemic subjects, while no significant differences were observed with respect to DNA strand breakage between the two groups. Hypercholesterolemia is related to oxidative stress and inflammation. Accordingly, AOPP concentration was higher in subjects with hypercholesterolemia, and we speculate that AOPP can reflect the enhancement of protein oxidation and inflammation.  相似文献   
22.
23.
24.
Uganda is the only African country whose onchocerciasis elimination program uses a two-pronged approach of vector control and mass drug distribution. The Ugandan program relies heavily upon the use of serosurveys of children to monitor progress toward elimination. The program has tested over 39,000 individuals from 11 foci for Onchocerca volvulus exposure, using the Ov16 ELISA test. The data show that the Ov16 ELISA is a useful operational tool to monitor onchocerciasis transmission interruption in Africa at the World Health Organization (WHO) recommended threshold of < 0.1% in children. The Ugandan experience has also resulted in a re-examination of the statistical methods used to estimate the boundary of the upper 95% confidence interval for the WHO prevalence threshold when all samples tested are negative. This has resulted in the development of Bayesian and hypergeometric statistical methods that reduce the number of individuals who must be tested to meet the WHO criterion.  相似文献   
25.
26.
27.
BACKGROUND: Few reports have addressed the value of unfractionated heparin (UFH) or low-molecular-weight heparin in treating the full spectrum of patients with venous thromboembolism (VTE), including recurrent VTE and pulmonary embolism. METHODS: In an open, multicenter clinical trial, 720 consecutive patients with acute symptomatic VTE, including 119 noncritically ill patients (16.5%) with pulmonary embolism and 102 (14.2%) with recurrent VTE, were randomly assigned to treatment with subcutaneous UFH with dose adjusted by activated partial thromboplastin time by means of a weight-based algorithm (preceded by an intravenous loading dose), or fixed-dose (adjusted only to body weight) subcutaneous nadroparin calcium. Oral anticoagulant therapy was started concomitantly and continued for at least 3 months. We recorded the incidence of major bleeding during the initial heparin treatment and that of recurrent VTE and death during 3 months of follow-up. RESULTS: Fifteen (4.2%) of the 360 patients assigned to UFH had recurrent thromboembolic events, as compared with 14 (3.9%) of the 360 patients assigned to nadroparin (absolute difference between rates, 0.3%; 95% confidence interval, -2.5% to 3.1%). Four patients assigned to UFH (1.1%) and 3 patients assigned to nadroparin (0.8%) had episodes of major bleeding (absolute difference between rates, 0.3%; 95% confidence interval, -1.2% to 1.7%). Overall mortality was 3.3% in each group. CONCLUSIONS: Subcutaneous UFH with dose adjusted by activated partial thromboplastin time by means of a weight-based algorithm is as effective and safe as fixed-dose nadroparin for the initial treatment of patients with VTE, including those with pulmonary embolism and recurrent VTE.  相似文献   
28.
Tetraethylammonium (Et(4)N(+)) ions depressed the amplitude and accelerated the decay rate of spontaneously occurring and nerve-evoked endplate currents (EPCs) in frog sartorius muscle. The relationship between peak EPC amplitude and membrane potential became nonlinear in the presence of 100 muM Et(4)N(+), and with drug concentrations of 250 muM or greater the current-voltage relationship exhibited negative conductance in the hyperpolarized region. Et(4)N(+) modified the exponential dependence of the EPC decay on membrane potential such that the decays between -150 and -50 mV were abbreviated and voltage independent but remained near control levels at more positive membrane potentials. The minimal effective concentration of Et(4)N(+) for altering the EPC time course was 10, and maximal effects were attained with 100 muM. Little additional shortening in the EPC decay phase was detected on raising the drug concentration to 1000 muM. Acetylcholine noise analysis revealed a voltage-dependent reduction in the mean channel open time, which was comparable in magnitude to the shortening in the EPC decay, and a depression of single-channel conductance. In concomitant biochemical studies, Et(4)N(+) was found to inhibit the binding of both [(3)H]acetylcholine and [(3)H]perhydrohistrionicotoxin to receptor-rich membranes from the electric organ of Torpedo ocellata with K(i) values of 200 muM and 280 muM, respectively. These results suggest that Et(4)N(+) interacts with both the acetylcholine receptor and its associated ionic channel. The voltage-dependent actions of Et(4)N(+) are attributed to blockade of the ionic channel in closed as well as open conformation.  相似文献   
29.
30.
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