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   42175篇
  免费   1477篇
  国内免费   219篇
耳鼻咽喉   323篇
儿科学   952篇
妇产科学   623篇
基础医学   5945篇
口腔科学   1635篇
临床医学   3310篇
内科学   7888篇
皮肤病学   702篇
神经病学   3961篇
特种医学   1644篇
外国民族医学   3篇
外科学   5797篇
综合类   1970篇
一般理论   34篇
预防医学   2586篇
眼科学   596篇
药学   3125篇
  28篇
中国医学   138篇
肿瘤学   2611篇
  2023年   236篇
  2022年   570篇
  2021年   1439篇
  2020年   852篇
  2019年   1242篇
  2018年   1915篇
  2017年   1222篇
  2016年   1669篇
  2015年   1886篇
  2014年   2236篇
  2013年   2847篇
  2012年   3035篇
  2011年   2455篇
  2010年   2270篇
  2009年   1800篇
  2008年   2039篇
  2007年   2023篇
  2006年   1854篇
  2005年   1704篇
  2004年   1485篇
  2003年   1074篇
  2002年   904篇
  2001年   587篇
  2000年   670篇
  1999年   587篇
  1998年   337篇
  1997年   280篇
  1996年   245篇
  1995年   174篇
  1994年   187篇
  1993年   172篇
  1992年   359篇
  1991年   295篇
  1990年   291篇
  1989年   259篇
  1988年   223篇
  1987年   199篇
  1986年   203篇
  1985年   178篇
  1984年   149篇
  1983年   89篇
  1982年   89篇
  1981年   63篇
  1980年   71篇
  1979年   89篇
  1977年   56篇
  1972年   69篇
  1971年   66篇
  1970年   58篇
  1968年   73篇
排序方式: 共有10000条查询结果,搜索用时 358 毫秒
41.
A rapid procedure for determining angiotensin II in the blood by inverse voltammetry using a TA-2 device (Tekhnoanalit Company, Tomsk) with a graphite electrode has been developed. The results of analyses using the proposed technique agree with the clinical data. The rapid analytical procedure favors optimization of cardiotropic drug therapy. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 12, pp. 54–56, December, 2006.  相似文献   
42.
The in vitro activities of povidone iodine, potassium peroxymonosulfate, and dimethyldidecylammonium chloride were investigated against 379 nosocomial isolates of Staphylococcus aureus and Pseudomonas aeruginosa responsible for surgical wound infections in patients operated on between July 1995 and June 2001. Overall, the isolates were inhibited by the antiseptics at concentrations below those used routinely. In spite of increasing resistance to the various antibiotics used to treat surgical wound infections, no significant variation in the susceptibility to antiseptics was demonstrated during this 6-year study. Electronic Publication  相似文献   
43.
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   
44.
45.
46.
Background  Stress gated myocardial perfusion single photon emission computed tomography (gSPECT) is increasingly used before and after intercurrent therapeutic intervention and is the basis for ongoing evaluation in the Department of Veterans Affairs clinical outcomes utilizing revascularization and aggressive drug evaluation (COURAGE) trial. Methods and Results  The COURAGE trial is a North American multicenter randomized clinical trial that enrolled 2287 patients to aggressive medical therapy vs percutaneous coronary intervention plus aggressive medical therapy. Three COURAGE nuclear substudies have been designed. The goals of substudy 0 are to examine the diagnostic accuracy of the extent and severity of inducible ischemia at baseline in COURAGE patients compared with patient symptoms and quantitative coronary angiography and to explore the relationship between inducible ischemia and the benefit from revascularization when added to medical therapy. Substudy 1 will correlate the extent and severity of provocative ischemia with the frequency, quality, and instability of recurrent symptoms in postcatheterization patients. Substudy 2 (n _ 300) will examine the usefulness of sequential gSPECT monitoring 6 to 18 months after therapeutic intervention. Together, these nuclear substudies will evaluate the role of gSPECT to determine the effectiveness of aggressive risk-factor modifications, lifestyle interventions, and anti-ischemic medical therapies with or without revascularization in reducing patients’ ischemic burdens. Conclusions  The unfolding of evidence on the application of gSPECT in trials such as COURAGE defines a new era for nuclear cardiology. We hope the evidence that emerges from the COURAGE trial will further establish the role of nuclear imaging in the evidence-based management of patients with stable coronary disease. The COURAGE trial was supported by the Cooperative Studies Program of the Department of Veterans Affairs Office of Research and Development in collaboration with the Canadian Institutes of Health Research. Unrestricted research grants were obtained from Merck & Co; Pfizer Pharmaceuticals; Bristol-Myers Squibb Medical Imaging; Astellas Pharma; Kos Pharmaceuticals; Data Scope; Astra Zeneca Pharmaceuticals; Astra-Zeneca-Canada; Schering-Plough Coorporation, Ltd; Sanofi-Aventis, Inc; First Horizon; and GE Healthcare. All industrial funding for this trial was directed through the Department of Veterans Affairs. Additional funding for this substudy was provided by grants to the Department of Veterans Affairs and Canadian Institutes of Health Research from Astellas Pharma and Bristol-Myers-Squibb Medical Imaging.  相似文献   
47.
48.
FDA’S Perspectives on Cardiovascular Devices   总被引:1,自引:0,他引:1  
The Food and Drug Administration (FDA) decision process for approving or clearing medical devices is often determined by a review of robust clinical data and extensive preclinical testing of the device. The mission statement for the Center for Devices and Radiological Health (CDRH) is to review the information provided by manufacturers so that it can promote and protect the health of the public by ensuring the safety and effectiveness of medical devices deemed appropriate for human use (Food, Drug & Cosmetic Act, §903(b)(1, 2(C)), December 31, 2004; accessed December 17, 2008 ). For high-risk devices, such as ventricular assist devices (VADs), mechanical heart valves, stents, cardiac resynchronization therapy (CRT) devices, pacemakers, and defibrillators, the determination is based on FDA’s review of extensive preclinical bench and animal testing followed by use of the device in a clinical trial in humans. These clinical trials allow the manufacturer to evaluate a device in the intended use population. FDA reviews the data from the clinical trial to determine if the device performed as predicted and the clinical benefits outweigh the risks. This article reviews the regulatory framework for different marketing applications related to cardiovascular devices and describes the process of obtaining approval to study a cardiovascular device in a U.S. clinical trial.  相似文献   
49.
50.
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