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   1532077篇
  免费   114767篇
  国内免费   5126篇
耳鼻咽喉   19014篇
儿科学   48636篇
妇产科学   40075篇
基础医学   222442篇
口腔科学   39792篇
临床医学   150005篇
内科学   299352篇
皮肤病学   29241篇
神经病学   131998篇
特种医学   57027篇
外国民族医学   379篇
外科学   215190篇
综合类   31021篇
现状与发展   2篇
一般理论   624篇
预防医学   128475篇
眼科学   33843篇
药学   111937篇
  7篇
中国医学   3448篇
肿瘤学   89462篇
  2021年   15311篇
  2019年   15823篇
  2018年   21412篇
  2017年   15996篇
  2016年   17353篇
  2015年   19953篇
  2014年   27797篇
  2013年   41554篇
  2012年   58613篇
  2011年   61989篇
  2010年   35643篇
  2009年   32849篇
  2008年   56092篇
  2007年   59133篇
  2006年   58951篇
  2005年   57263篇
  2004年   54381篇
  2003年   51224篇
  2002年   49441篇
  2001年   62512篇
  2000年   63755篇
  1999年   54002篇
  1998年   16958篇
  1997年   15166篇
  1996年   14767篇
  1995年   13975篇
  1994年   12959篇
  1993年   12212篇
  1992年   42425篇
  1991年   41538篇
  1990年   40114篇
  1989年   37974篇
  1988年   35173篇
  1987年   34242篇
  1986年   32696篇
  1985年   31219篇
  1984年   23792篇
  1983年   20257篇
  1982年   12631篇
  1981年   11105篇
  1979年   21195篇
  1978年   15276篇
  1977年   12450篇
  1976年   12240篇
  1975年   12378篇
  1974年   15068篇
  1973年   14703篇
  1972年   13513篇
  1971年   12563篇
  1970年   11577篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Art and soul     
L Dopson 《Nursing times》1987,83(46):16-17
  相似文献   
942.
The structural behaviour of cobalt(II)phthalocyanine-tetrasodium sulfonate (CoPc(NaSO3)4) ( 1 ), a catalyst used in thiol oxidation, was investigated in the presence of ionenes (poly-quaternary ammonium salts), ( 2 ) using visible light spectroscopy. It was observed that ionenes, which have been shown to promote the catalytic activity, strongly enhance the aggregation of the cobalt complex. No cobalt site isolation occurred up to N+/Co = 105. Furthermore, a stoichiometric CoPc(NaSO3)4/ionene complex appeared to be formed with an N+/Co-ratio of 4:1. This ratio was found to hold for ionenes with M?n varying from 6 100 to 22 000 and charge densities from 0,8 to 1,5. As the charge density was increased, the observed CoPc(NaSO3)4 spectrum was more affected. Experiments with oxygen in alkaline solution revealed that the complex was resistant toward oxygen adduct formation in the presence of ionenes. This phenomenon is discussed in relation to the catalytic activity of the system.  相似文献   
943.
944.
945.
Adenoviruses are commonly used as vectors in human clinical gene therapy trials. High doses of intravenous adenovirus vectors have been associated with development of thrombocytopenia of undetermined origin. Viral internalization requires the presence cell surface integrins, alpha(v)beta(3) or alpha(v)beta(5), that can blind ligands with a arginine-glycine-aspartic acid (RGD) sequence. This sequence is found in the adenovirus penton base. Platelets express the alpha(v)beta(3) integrin and other integrins that bind the RGD sequence of ligands such as fibrinogen, laminin, vitronectin, and von Willebrand factor (vWF). Platelet aggregation is mediated, in part, by the binding of the RGD sequence of fibrinogen to a platelet surface integrin, glycoprotein IIb/IIIa (GP IIb/IIIa). We investigated whether adenovirus particles could interfere with or potentiate agonist-induced platelet aggregation. Incubation of platelet-rich plasma with adenovirus under stirred conditions did not promote spontaneous aggregation. The addition of physiological platelet agonists, ADP, collagen, or epinephrine, induced platelet aggregation. However, the presence of adenovirus in a wide range of concentrations did not inhibit or potentiate agonist-induced aggregation. These results suggest that the adenovirus-associated thrombocytopenia observed in vivo is independent of a direct effect of the virus on platelet aggregation.  相似文献   
946.
Interest in inguinal hernia surgery has increased significantly with the introduction of new operating techniques during the past decade. This multicenter study compared short-term results in patients treated by the laparoscopic transabdominal preperitoneal patch technique (TAPP; n=518) and the Shouldice technique (n=524). We evaluated demographics, operative data, complications, hospital stay, postoperative pain, use of analgesics, functional status, sick leave, and complaints up to 3 months postoperatively. The median operating time was shorter in the Shouldice group (55 vs. 65 min), but there were no significant differences in complication rates, and major complications were rare. The hospital stay was 1 day or less in over 98% of cases in both groups, but more operations were performed on outpatient basis in the Shouldice group. In the TAPP group postoperative pain and analgesic consumption were less, postoperative functional status was better, and sick leave was shorter (10 vs. 14 days). These results show that the two methods are equally safe and have few major complications. The TAPP operation is associated with less postoperative pain, better postoperative functional status, and shorter sick leave, but at the price of a longer operating time. Electronic Publication  相似文献   
947.
The carcinogenicity of dextran and 3 kinds of dextran sulfate sodium with different molecular weights and almost the same sulfur content were compared in ACI rats. Dextran sulfate sodium of molecular weight 54,000 showed a strong carcinogenic activity when it was given orally as 2.5% diet, whereas dextran sulfate sodium of molecular weight 520,000 and 9500 and dextran showed no significant carcinogenicity, i.e. the peak of carcinogenic activity of dextran sulfate sodium appeared at molecular weight 54,000, and dextran sulfates with larger or smaller molecular weights had no carcinogenic activity.  相似文献   
948.
949.
950.
Nonhair-bearing skin should be used when grafting is necessary during urethroplasty for stricture or hypospadias repair. Occasionally, this is not possible or hair-bearing skin is used inadvertently. Traditionally, electrocoagulation has been the method used for epilation when intraluminal hair has become a problem, such as interfering with flow, as a focus for recurrent urinary tract infection or acting as a nidus for calculus formation. Electrocautery also is performed during grafting in an attempt to prevent the growth of hair when hair-bearing skin is used. Unfortunately, due to lack of penetration the hair follicles are not destroyed and the epilating procedure fails or is only partially successful. The neodymium:YAG surgical laser can photocoagulate tissue to a depth up to 5.0 mm, and thus, has the ability to destroy hair follicles. We report 4 cases presenting with clinical problems directly related to hair-bearing urethral grafts successfully treated by neodymium:YAG laser epilation.  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