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   1086575篇
  免费   73778篇
  国内免费   1447篇
耳鼻咽喉   15408篇
儿科学   35531篇
妇产科学   29061篇
基础医学   154429篇
口腔科学   30172篇
临床医学   95994篇
内科学   205820篇
皮肤病学   24778篇
神经病学   82310篇
特种医学   43506篇
外国民族医学   202篇
外科学   166163篇
综合类   21903篇
现状与发展   2篇
一般理论   269篇
预防医学   75145篇
眼科学   24921篇
药学   86838篇
  7篇
中国医学   2900篇
肿瘤学   66441篇
  2019年   7953篇
  2018年   11647篇
  2017年   9211篇
  2016年   10433篇
  2015年   11561篇
  2014年   15689篇
  2013年   22775篇
  2012年   31347篇
  2011年   33291篇
  2010年   19469篇
  2009年   18103篇
  2008年   30648篇
  2007年   32975篇
  2006年   33572篇
  2005年   32018篇
  2004年   30569篇
  2003年   29345篇
  2002年   28296篇
  2001年   60415篇
  2000年   61953篇
  1999年   51249篇
  1998年   12549篇
  1997年   11081篇
  1996年   11084篇
  1995年   10378篇
  1994年   9379篇
  1993年   8887篇
  1992年   37877篇
  1991年   36334篇
  1990年   35802篇
  1989年   34336篇
  1988年   30902篇
  1987年   30031篇
  1986年   28256篇
  1985年   26485篇
  1984年   19206篇
  1983年   16133篇
  1982年   8831篇
  1979年   17053篇
  1978年   11419篇
  1977年   10239篇
  1976年   8849篇
  1975年   10080篇
  1974年   11679篇
  1973年   11289篇
  1972年   10765篇
  1971年   10112篇
  1970年   9273篇
  1969年   8952篇
  1968年   7928篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
About 85% of the population of two Somali communities harboured soil-transmitted intestinal nematodes and/or protozoa. The commonest parasite (75% in the Lafoole institution and 59% in the Afgoye institution) was Trichuris trichiura. Mixed infections were common. The source of infection is contaminated fields around dwelling quarters, because of indiscriminate defaecation. One of the factors responsible for the higher incidence of hookworm in Lafoole (45%) compared with Afgoye (1.5%) may be the different soil character of the surrounding fields.  相似文献   
992.
The Australian government established the Council on Overseas Professional Qualifications (COPQ) in 1969. In response to approaches by the occupational therapy profession, an Expert Panel in Occupational Therapy was established in 1979 in order to develop a screening examination to be used in assessing the competency of overseas trained occupational therapists. This paper describes the development of the COPQ examination for all overseas qualified occupational therapists wishing to work in Australia; the experience of candidates since its inception in 1983; and the problems associated with achieving recognition of the COPQ examination throughout Australia given the lack of uniform recognition procedures in the various States and Territories. The need for a consistent national approach to the policy of recognition and employment of overseas trained occupational therapists is addressed, with stress placed on the need for all employer groups, in both the public and the private sectors, to cooperate with COPQ's assessment procedures.  相似文献   
993.
994.
995.
Delta hepatitis virus infection in China   总被引:1,自引:0,他引:1  
To assess the prevalence, epidemiological features and prognostic implications of hepatitis D (Delta) in Sichuan Province, The People's Republic of China, 649 sera (515 from HBsAg positive patients and 134 from HBsAg negative subjects) were tested by radioimmunoassay (RIA) for antibody to the hepatitis D virus (anti-HD). Forty-seven sera (7.2%) showed some degree of reactivity. Serial dilutions of these sera indicated that prozoning was not responsible for the equivocal results. Thirty-four of the 47 sera were submitted under code to a second laboratory for independent analysis. According to those results anti-HD antibodies were detected in four of these sera. The overall prevalence of anti-HD in the HBsAg positive patients therefore was 0.8% (4/515). On the basis of clinical, biochemical and histological data 427 HBsAg positive sera were further divided into acute Type B hepatitis, chronic Type B hepatitis, healthy carrier state and hepatocellular carcinoma (HCC) subgroups. Two of 65 (3.1%) anti-HD positive sera belonged to the acute Type B hepatitis group; one of 104 (0.9%), the chronic Type B hepatitis group and one of 246 (0.4%), the healthy carrier group. No antibody was detected in sera from 12 HBsAg positive HCC patients. All HBsAg negative patients were negative for anti-HD antibody. The results of this study indicate that despite a high prevalence of hepatitis B virus infection, positive serology for delta virus is uncommon in Sichuan Province, The People's Republic of China.  相似文献   
996.
997.
The return of fertility following discontinuation of norethisterone oenanthate (NET EN) 200 mg injectable contraceptive after use for a minimum period of six months or more was studied in 69 women who discontinued the method for planning pregnancy. Former users of copper intra-uterine device (CuT 200) were enrolled as a control group. Another 161 women who had discontinued NET EN due to other reasons (e.g. amenorrhoea, excessive bleeding or personal reasons) were also studied for return of fertility after ensuring that they were not using any other method of contraception and were exposed to the risk of pregnancy. The subjects from both groups were followed for a period of one year. The cumulative conception rates at one year were 72.5 and 83.6 per 100 subjects for ex-NET EN and ex-CuT 200 users who had discontinued the method for planning pregnancy and this difference was not statistically significant (P > 0.05). The median time for conception for ex-NET EN users was 7.8 months as compared to 3.7 months in ex-CuT 200 users but the cumulative conception rates at the end of one year show that future return of fertility in NET EN users does not appear to be adversely affected.

In 51 subjects who had discontinued NET EN due to amenorrhoea, the return of fertility was predictably slower and less. The return of fertility in subjects who discontinued NET EN for other reasons (e.g. excessive bleeding and other personal reasons) was similar to ex-NET EN and ex-CuT 200 users.  相似文献   

998.
Growing rats were fed ad libitum soy protein isolate (SPI) or its peptic (SPI-P) or tryptic digest (SPI-T) for a month and their sera were examined for cholesterol and triglyceride levels and enzyme activities such as cholinesterase, glutamate-pyruvate transaminase (GPT) and alkaline phosphatase. The rats fed SPI-P or SPI-T were inferior in growth to those fed SPI. Similarly, the serum glyceride level was lower in the SPI-P and SPI-T groups than in the SPI group. On the other hand, a significant difference was found in the serum cholesterol level between the SPI-P and SPI or SPI-T groups but not between the SPI and SPI-T groups. A similar tendency was observed for serum GPT and alkaline phosphatase activities, although there were no significant differences among dietary groups in small intestinal enzyme activities. As for the atherogenic index being a risk factor inducing atherosclerosis, the order of its value was SPI-P less than SPI less than SPI-T.  相似文献   
999.
Follicular fluids from eight patients with one ovary and from ten patients with two ovaries were investigated for bioactive inhibin, total renin, oestradiol (E2) and progesterone (P4) concentrations. Four follicular fluids were pooled per patient before assessment. All women had been stimulated similarly using a protocol including a GnRH agonist, HMG and HCG. Renin levels were significantly lower and P4 significantly higher in pools of follicular fluid from patients with one ovary, whereas inhibin and E2 concentrations were similar in both patient groups. A significant negative correlation was found in the pools of follicular fluid between inhibin and E2 in both groups. These results suggest a role for inhibin and renin in the paracrine and autocrine control of stimulated follicular development.  相似文献   
1000.
The cytoskeleton is susceptible to oxidative stress and this occurs prior to membrane blebbing and cell lysis. Vimentin intermediary filaments in rheumatoid synoviocytes are more susceptible than in normal synoviocytes and this may have pathological significance. They are however no more susceptible to heat shock than other cell types.  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