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   19424篇
  免费   1194篇
  国内免费   49篇
耳鼻咽喉   158篇
儿科学   656篇
妇产科学   437篇
基础医学   2918篇
口腔科学   295篇
临床医学   1937篇
内科学   4296篇
皮肤病学   242篇
神经病学   2136篇
特种医学   744篇
外国民族医学   3篇
外科学   2412篇
综合类   197篇
一般理论   7篇
预防医学   1217篇
眼科学   662篇
药学   923篇
中国医学   41篇
肿瘤学   1386篇
  2021年   227篇
  2020年   148篇
  2019年   265篇
  2018年   302篇
  2017年   243篇
  2016年   288篇
  2015年   314篇
  2014年   401篇
  2013年   597篇
  2012年   882篇
  2011年   939篇
  2010年   521篇
  2009年   485篇
  2008年   756篇
  2007年   888篇
  2006年   880篇
  2005年   845篇
  2004年   855篇
  2003年   758篇
  2002年   791篇
  2001年   631篇
  2000年   615篇
  1999年   491篇
  1998年   208篇
  1997年   182篇
  1996年   152篇
  1995年   176篇
  1994年   147篇
  1993年   143篇
  1992年   437篇
  1991年   416篇
  1990年   411篇
  1989年   358篇
  1988年   350篇
  1987年   340篇
  1986年   349篇
  1985年   314篇
  1984年   267篇
  1983年   229篇
  1982年   163篇
  1981年   158篇
  1980年   137篇
  1979年   219篇
  1978年   188篇
  1976年   139篇
  1975年   140篇
  1974年   170篇
  1973年   164篇
  1972年   135篇
  1971年   135篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Antibodies against neutrophils have been detected in sera from patients with primary sclerosing cholangitis and inflammatory bowel diseases either by immunofluorescence or by enzyme-linked immunosorbent assay. To assess primary sclerosing cholangitis-specific antibodies, we examined sera from 30 patients with clinically and morphologically well-established primary sclerosing cholangitis by Western blotting against neutrophils and compared these results with those obtained by testing sera from patients with inflammatory bowel diseases. By Western blot using sonified neutrophils, 24 (80%) of 30 primary sclerosing cholangitis sera were positive. Five antigenic determinants at 95, 60, 55, 40 and 30 kD were visualized. Twenty-eight of the primary sclerosing cholangitis sera also showed the characteristic perinuclear fluorescence pattern by immunofluorescence on neutrophils. Thus a serological diagnosis of primary sclerosing cholangitis could be made in 80% of patients based on these two methods. In contrast, only 9% of 23 patients with ulcerative colitis and 10% of 60 patients with Crohn's disease were positive by Western blot, and these patients also showed positive perinuclear fluorescence pattern by immunofluorescence, suggesting an overlap between inflammatory bowel diseases and primary sclerosing cholangitis. Although some patients with classical primary biliary cirrhosis and autoimmune chronic active hepatitis had antibodies against primary sclerosing cholangitis epitopes, none of the patients with obstructive bile duct disorders, collagen diseases, Wegener's granulomatosis or other hepatic and nonhepatic disorders were positive by Western blot, indicating the specificity of these five primary sclerosing cholangitis-related neutrophilic epitopes.  相似文献   
22.
The Toronto Sexual Contact Study comprises a cohort of 249 male sexual contacts of men with HIV disease which has been followed every 3 months for almost 5 years. On enrollment 143 were seropositive and 16 seroconverted during the follow-up period. By 31 December 1989, 41 of the 159 seropositive cohort members had developed AIDS. Using Cox relative risk regression models, we investigated the association of a number of laboratory and clinical variables and progression to AIDS. Fixed covariate models examined laboratory variables from the enrollment visit of cohort members, with time calculated from this date. In models assessing time dependent covariates, time was calculated from the estimated date of HIV infection. In the univariate models of either fixed or time dependent covariates, many variables were significantly associated with risk of progression to AIDS (T4 cell count, T4/T8 ratio, blastogenic responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen, serum IgA, appearance of p24 antigen, and the development of oral hairy leukoplakia, thrush, or herpes zoster). Appearance of persistent generalized lymphadenopathy was not associated with increased risk of progression. In the multivariate model which evaluated fixed laboratory covariates, T4/T8 ratio, IgA level, and PHA response at enrollment were significantly associated with elevated risk.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
23.
24.
25.
Hearing aids with signal processors use advanced circuitry to enhance speech recognition in noise. The effectiveness of these processors has not been well established. The purpose of this study was to evaluate performance on a speech recognition in noise task for listeners wearing a Zeta signal processor aid with the processor turned on and with the processor turned off. In addition, comparisons were made to performance while unaided and aided with a conventional hearing aid. A simple adaptive procedure and a psychometric function were the procedures used. Results for normal-hearing subjects indicate performance was usually better without a hearing aid. Performance when aided was similar for the processor on and the conventional aid. Performance in both of these conditions was clearly better than with the signal processor off. Although results for the hearing-impaired subjects varied widely, there was a trend for better performance with the conventional aid and with the signal processor on than for the signal processor off condition.  相似文献   
26.
27.
28.
78 geriatric patients predominantly suffering from cardiocerebrovascular diseases (stroke, heart insufficiency) and lesions respectively operations of the locomotion system (fractures, arthroses) were admitted in 1987 from acute hospitals for after-treatment (short-term care). 35 (= 45%) of them (average age 80 (61-92) could be discharged after 63.5 days on average, 11 died from intercurrent complications, 9 remained for long-term care as inrehabilitable. Besides other concomiting troubles mainly cardiac and circulation affections were present in the majority of patients. Their identification (a. o. by means of ultrasonic methods) and therapy also means a secondary prevention of cerebral as well as of fall and injuries inducing risk factors. The results confirm the principal rehabilitation chance of multimorbid geriatric patients by use of the diagnostic and therapeutic special potential of geriatrics.  相似文献   
29.
30.
A prospective study of 35 patients in the neonatal intensive care unit was conducted to examine the safety and feasibility of percutaneous Silastic central venous catheters for the provision of prolonged parenteral alimentation. Particular attention was directed to the possibility of maintaining these lines through intercurrent episodes of infection. Catheters were placed in 34 infants (97%). At the time of insertion, 21 patients (62%) weighed less than 1000 gm and 13 patients (38%) weighed less than 750 gm. The average duration of catheterization was 32.0 +/- 18.2 (SD) days; 19 patients (56%) had lines in place for more than 30 days. Mechanical difficulties complicated the course of five patients (15%). Four cases of bacteremia were identified; this represents 3.7 infections/1000 days of catheter use. All infections were caused by methicillin-resistant staphylococci. Two patients required catheter removal to clear their infection, but in two of the four bacteremic patients, the infection was cleared and the line was sterilized by the administration of antibiotic therapy through the central catheter. We conclude that Silastic central venous catheters can be used safely to deliver intravenous nutrition to extremely small preterm infants over a prolonged period of time, and in carefully selected patients, successful treatment of complicating infections may be achieved without catheter removal.  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