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   4098篇
  免费   304篇
  国内免费   11篇
耳鼻咽喉   50篇
儿科学   136篇
妇产科学   118篇
基础医学   556篇
口腔科学   243篇
临床医学   289篇
内科学   919篇
皮肤病学   140篇
神经病学   215篇
特种医学   282篇
外科学   613篇
综合类   98篇
一般理论   2篇
预防医学   313篇
眼科学   24篇
药学   197篇
中国医学   45篇
肿瘤学   173篇
  2022年   33篇
  2021年   85篇
  2020年   71篇
  2019年   89篇
  2018年   104篇
  2017年   85篇
  2016年   90篇
  2015年   87篇
  2014年   110篇
  2013年   172篇
  2012年   184篇
  2011年   209篇
  2010年   152篇
  2009年   128篇
  2008年   193篇
  2007年   218篇
  2006年   178篇
  2005年   145篇
  2004年   161篇
  2003年   131篇
  2002年   137篇
  2001年   123篇
  2000年   131篇
  1999年   109篇
  1998年   95篇
  1997年   69篇
  1996年   62篇
  1995年   43篇
  1994年   48篇
  1993年   38篇
  1992年   81篇
  1991年   61篇
  1990年   69篇
  1989年   75篇
  1988年   91篇
  1987年   66篇
  1986年   66篇
  1985年   75篇
  1984年   44篇
  1983年   43篇
  1982年   27篇
  1981年   19篇
  1980年   17篇
  1979年   15篇
  1978年   20篇
  1977年   13篇
  1976年   13篇
  1972年   20篇
  1971年   18篇
  1967年   12篇
排序方式: 共有4413条查询结果,搜索用时 358 毫秒
81.
OBJECTIVE: To review the results and complications of thrombolysis in patients with acute myocardial infarction (AMI) and its complications. METHODS: Since june 1989 to august 1994 we studied patients with AMI, who underwent thrombolysis. Clinical characteristics, complications and angiographic results are described. RESULTS: Of the total population 86.3% patients received Streptokinase (SK) and 13.7% recombinant tissue plasminogen activator (rt-PA). In 20 patients the age was under 40 years, 373 between 40-70 years, and 80 patients over 70 years. 84% were men and 16% women. 72% had smoking habit; 21% diabetes mellitus, 43% hypertension, 54% had previous angina and previous AMI in 22%. The location of AMI was anterior in 234 patients and 239 inferior. In 63% enzyme washout was observed, and rapid electrocardiographic evolution in 81%. Postthrombolisis arrhythmias was observed in 64.7%. Major bleeding in 11.8% and central nervous system hemorrhage in 0.4% only with rt-PA. Postinfarction angina in 22%, and re-infarction in 4%. Cardiac rupture in 1.4%, with shock and death. Mitral insufficiency in 2.1% demonstrated by echocardiogram. Coronary angiography was done in 373 patients (80%), of which 50.7% was made in the first 5 days. The culprit artery was anterior descending in 273 patients and right coronary in 95. Left ventricular dysfunction was seen in 23% in patients with anterior AMI, and 5% with inferior AMI. Cardiogenic shock was seen in 7%. Coronary artery bypass grafting was undertaken in 106 patients and coronary angioplasty in 67. The ten days mortality was 8.8%, principally due to cardiogenic shock, ventricular arrhythmias and ventricular rupture. CONCLUSIONS: The usefull permeability in the culprit artery was obtained in 40%, who had coronary angiography done 145 hours posthrombolysis. Mortality was under 10% in this study.  相似文献   
82.
Neale  GA; Rehg  JE; Goorha  RM 《Blood》1995,86(8):3060-3071
Although the proto-oncogene rhombotin-2 (RBTN-2) is widely expressed in most tissues, it is not expressed in T cells. We investigated the potential for overexpression of RBTN-2 to cause tumors in T cells and other tissues by constructing transgenic mice that expressed RBTN-2 under control of the metallothionein-1 promoter. Despite overexpression of RBTN-2 in all tissues, transgenic mice developed T-cell tumors only, thus indicating that tumorigenesis caused by RBTN-2 is T-cell-specific. Thymic tumors were found between 37 and 71 weeks and were invariably associated with metastasis to nonlymphoid organs. Thymuses from apparently healthy transgenic mice were also examined. In some mice there was an 10-fold increase in the CD4-CD8- thymocyte subset, yet the total number of thymocytes was the same as that in wild-type mice. Thymic homeostasis was maintained by a compensatory reduction in the CD4+CD8+ subset. The expansion of CD4-CD8- thymocytes was associated with increased expression of RBTN-2 and with increased cell proliferation. No differences were found in the proportion of thymocytes undergoing apoptosis in transgenic mice. Furthermore, RBTN-2- induced expansion of CD4-CD8- cells did not block differentiation of these cells. Thymuses with 30% CD4-CD8- cells were essentially monoclonal, indicating that all thymic immunophenotypes were derived from a single clone. Overall, our data are consistent with the following scenario: (1) RBTN-2 expression in T cells causes selective and polyclonal proliferation of CD4-CD8- thymocytes accompanied by a compensatory decrease in other thymocyte subsets; (2) a clone with growth advantage and differentiation potential is selected and populates the thymus; and (3) this clone eventually breaches homeostasis of the thymus, accompanied or followed by metastasis to other organs.  相似文献   
83.
Since the introduction of erythromycin in 1965, no new compounds from the macrolide antimicrobial class were licensed in Canada until the 1990s. Clarithromycin and azithromycin, since their introduction, have become important agents for treating a number of common and uncommon infectious diseases. They have become prime agents in the treatment of respiratory tract infections, and have revolutionized the management of both genital chlamydial infections, by the use of single-dose therapy with azithromycin, and nontuberculous mycobacterial infections, by the use of clarithromycin. The improvement of clarithromycin and azithromycin over the gastrointestinal intolerability of erythromycin has led to supplanting the use of the latter for many primary care physicians. Unfortunately, the use of these agents has also increased the likelihood for misuse and has raised concerns about a resultant increase in the rates of macrolide resistance in many important pathogens, such as Streptococcus pneumoniae. This paper reviews the pharmacology and evidence for the current indications for use of these newer agents, and provides recommendations for appropriate use.Key Words: Azithromycin, Clarithromycin, Erythromycin, Macrolides, Review, Therapeutic useErythromycin A is a naturally occurring, microbiologically active compound of the macrolide class of antibiotics. Chemical modification of erythromycin A''s 14-membered lactone ring has led to the formation of semisynthetic derivatives with not only improved bioavailability and tolerability, but also expanded spectrums of microbiological activity and improved pharmacokinetic profiles. Such modifications produced clarithromycin, classified as a macrolide because it retains the central 14-membered lactone ring (1,2), and azithromycin, classified as an azalide due to its 15-membered aglycone ring (1). The latter two compounds are the newest agents in the macrolide class licensed for use in Canada. Roxithromycin and dirithromycin are available in other countries.These compounds are clinically active against Gram-positive and Gram-negative cocci, and Gram-negative bacilli (primarily Haemophilus influenzae, Legionella species, Moraxella catarrhalis, Campylobacter jejuni, Bordatella pertussis and Helicobacter pylori). Azalides such as azithromycin have exhibited superior activity against Gram-negative pathogens and are generally less active against Gram-positive pathogens. Intracellular pathogens such as Chlamydia species, Mycoplasma species, Ureaplasma species, Borrelia species and nontuberculous mycobacteria species show varying susceptibilities. On the basis of their microbial activity, both the macrolides and azalides have been shown to be clinically useful in the treatment of uncomplicated skin and soft tissue infections, upper and lower respiratory tract infections, sexually transmitted Chlamydia trachomatis infection and peptic ulcer disease. Additionally, the improved pharmacokinetic profiles and acid stability exhibited by the newer agents may lead to enhanced patient adherence through less frequent dosing and improved bioavailability in the presence of food.  相似文献   
84.
85.
86.
87.
During 2010–2012, an outbreak of 210 cases of malaria occurred in Tumbes, in the northern coast of Peru, where no Plasmodium falciparum malaria case had been reported since 2006. To identify the source of the parasite causing this outbreak, we conducted a molecular epidemiology investigation. Microsatellite typing showed an identical genotype in all 54 available isolates. This genotype was also identical to that of parasites isolated in 2010 in the Loreto region of the Peruvian Amazon and closely related to clonet B, a parasite lineage previously reported in the Amazon during 1998–2000. These findings are consistent with travel history of index case-patients. DNA sequencing revealed mutations in the Pfdhfr, Pfdhps, Pfcrt, and Pfmdr1 loci, which are strongly associated with resistance to chloroquine and sulfadoxine/pyrimethamine, and deletion of the Pfhrp2 gene. These results highlight the need for timely molecular epidemiology investigations to trace the parasite source during malaria reintroduction events.  相似文献   
88.
Clinical Rheumatology - The evidence shows that previous infection with enteric pathogens is a requirement to develop pSpA. Based on our previous results, variances on regulation of SIgA might...  相似文献   
89.
90.
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