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   1698239篇
  免费   124112篇
  国内免费   3789篇
耳鼻咽喉   21755篇
儿科学   55809篇
妇产科学   46236篇
基础医学   241675篇
口腔科学   48843篇
临床医学   151582篇
内科学   334024篇
皮肤病学   38908篇
神经病学   131339篇
特种医学   63909篇
外国民族医学   242篇
外科学   257476篇
综合类   39008篇
现状与发展   4篇
一般理论   531篇
预防医学   124427篇
眼科学   40404篇
药学   123952篇
  7篇
中国医学   4493篇
肿瘤学   101516篇
  2021年   13000篇
  2019年   13648篇
  2018年   20095篇
  2017年   15313篇
  2016年   16745篇
  2015年   19066篇
  2014年   26370篇
  2013年   38115篇
  2012年   52967篇
  2011年   55654篇
  2010年   32928篇
  2009年   30816篇
  2008年   51674篇
  2007年   54927篇
  2006年   55398篇
  2005年   52671篇
  2004年   50858篇
  2003年   48249篇
  2002年   46481篇
  2001年   91810篇
  2000年   93655篇
  1999年   76994篇
  1998年   19742篇
  1997年   17285篇
  1996年   17404篇
  1995年   16753篇
  1994年   15299篇
  1993年   14078篇
  1992年   57398篇
  1991年   55283篇
  1990年   52990篇
  1989年   50760篇
  1988年   46145篇
  1987年   44945篇
  1986年   42234篇
  1985年   39994篇
  1984年   29352篇
  1983年   24914篇
  1982年   13901篇
  1979年   25535篇
  1978年   17578篇
  1977年   14910篇
  1976年   13875篇
  1975年   14565篇
  1974年   17633篇
  1973年   16946篇
  1972年   15676篇
  1971年   14459篇
  1970年   13432篇
  1969年   12519篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Mean cell volume and mean cell water content were examined in Plasmodium yoelii-infected mouse erythrocytes by gas chromatography and 3H-sucrose. Mean cell volume increased by 16% in infected erythrocytes with late trophozoites and schizonts. Mean cell water content further increased by 23% in the infected erythrocytes. Measurement of the erythrocyte potassium and sodium concentrations by an atomic absorption spectrophotometer revealed that the infected erythrocytes contained highly elevated sodium and slightly reduced potassium levels when calculated per single erythrocyte. It is suggested that membrane transport processes of sodium and potassium are changed in P. yoelii-infected erythrocytes and that a passive inflow of sodium takes place, which results in an increase in intra-erythrocytic water content.  相似文献   
992.
993.
994.
995.
Although jejunoileal bypass surgery proved effective in controlling morbid obesity, the serious adverse effects from the operation were ultimately found to outweigh the benefits. Gastric partitioning results in weight loss by restricting the volume of food ingested rather than by interfering with absorption. Vertical banded gastroplasty has fewer complications than Roux-en-Y gastric bypass and is currently the surgical procedure of choice for morbid obesity.  相似文献   
996.
The nuclear content, area and perimeter of the nucleus of lymphocytes in the C.S.F. were determined quantitatively by means of image analysis technique. 26 cases of central nervous system lymphocytic leukemia (CNLL), and 8 suspected cases were studied, other 56 cases who did not have leukemic and neoplastic diseases and had normal C.S.F. lymphocytes were taken as a control. Our data showed that all the mean nuclear content (MNC), mean nuclear area (MNA), mean nuclear perimeter (MNP), and the maximum and minimum nuclear contents of the 2 groups of former patients were obviously higher than those of the contral (P less than 0.01). These results presented suggestion that the image analysis technique can be used for differentiating the leukemic lymphocyte from normal one especially in suspected cases, and thus the diagnosis of CNLL might be improved.  相似文献   
997.
We have succeeded in recording short and middle latency vestibular evoked responses in human subjects. The head was held rigidly in a special, patented head holder, constructed individually for each subject, which gripped the teeth of the upper jaw. The stimulus consisted of 2/sec steps of angular acceleration impulses produced by a special motor with intensities of about 10,000 degrees/sec 2 and with a rise time of 1-2 msec. The electrical activity was recorded as the potential difference between special forehead and mastoid electrodes having a large, secure contact area with the skin. The activity was digitally filtered and averaged in 2 separate channels by means of a Microshev 2000 evoked response system. The short latency responses, with peaks at about 3.5 msec (forehead positive), 6.0 msec (forehead negative) and 8.4 msec (forehead positive; bandpass: 200-2000 Hz; average of 1024 trials), had amplitudes of about 0.5 microV. The middle latency responses had peaks at about 8.8 msec (forehead positive), 18.8 msec (forehead negative) and 26.8 msec (forehead positive; 30-300 Hz; N = 128 trials), with larger amplitudes (about 15 microV). These responses were consistently recorded in the same subject at different times and were similar in different normal subjects. Strenuous control experiments were conducted in order to ensure that these responses are not artefacts due to the movement of conducting media (head, electrodes and leads) in the electromagnetic field of the motor and are elicited by activation of normal labyrinths.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
998.
999.
Novel method for detecting micro-organisms in blood cultures.   总被引:13,自引:3,他引:10       下载免费PDF全文
A method for detecting the growth of micro-organisms in blood culture by a visual signal is described. The system utilises a single blood culture medium that has been specifically formulated to support growth of aerobic, anaerobic, and microaerophilic micro-organisms. The system is based on the principle that when micro-organisms grow in the medium in a sealed bottle their metabolic products create positive pressure. This positive pressure displaces the infected blood and broth into an upper chamber, which acts as a visual signal of microbial activity. All the test micro-organisms, when inoculated at less than 20 colony forming units into simulated human blood cultures, gave a positive signal.  相似文献   
1000.
Burkitt's lymphoma, characterized by jaw and abdominal tumors, is the most common early childhood malignancy in Central Africa and well-known in the United States, with only sporadic reports coming from other countries. Considered to be the fastest growing tumor in man, it is thought to be of viral etiology with warm, humid climate and malaria regarded as co-factors. This is the first case of Burkitt's lymphoma reported from Greece.  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