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   939241篇
  免费   66685篇
  国内免费   1374篇
耳鼻咽喉   13055篇
儿科学   24516篇
妇产科学   23405篇
基础医学   133843篇
口腔科学   28394篇
临床医学   81014篇
内科学   185232篇
皮肤病学   19367篇
神经病学   72703篇
特种医学   36982篇
外国民族医学   79篇
外科学   153327篇
综合类   18060篇
现状与发展   1篇
一般理论   234篇
预防医学   61974篇
眼科学   21460篇
药学   73163篇
  3篇
中国医学   2168篇
肿瘤学   58320篇
  2018年   9093篇
  2017年   7145篇
  2016年   7909篇
  2015年   9001篇
  2014年   12168篇
  2013年   17761篇
  2012年   24457篇
  2011年   25487篇
  2010年   15013篇
  2009年   14478篇
  2008年   24947篇
  2007年   26041篇
  2006年   26820篇
  2005年   25779篇
  2004年   24955篇
  2003年   23996篇
  2002年   23539篇
  2001年   54916篇
  2000年   56719篇
  1999年   47118篇
  1998年   10832篇
  1997年   9535篇
  1996年   9644篇
  1995年   8970篇
  1994年   8318篇
  1993年   7635篇
  1992年   35597篇
  1991年   34008篇
  1990年   32826篇
  1989年   31979篇
  1988年   29092篇
  1987年   28354篇
  1986年   26402篇
  1985年   25219篇
  1984年   17906篇
  1983年   15212篇
  1982年   7846篇
  1981年   6797篇
  1979年   15851篇
  1978年   10633篇
  1977年   9092篇
  1976年   7903篇
  1975年   8676篇
  1974年   10497篇
  1973年   9891篇
  1972年   9387篇
  1971年   8880篇
  1970年   8455篇
  1969年   7953篇
  1968年   7229篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
An analysis of mortality data for the years 1982-5 was carried out for the Micronesian population (aged 15 years and over) of the central Pacific Island, Nauru. Among males, the most common causes of death were circulatory system disorders (33.3%), accidents (25.2%), and diabetes mellitus (12.1%). The majority of accidents occurred in the 15-34 year age group and involved motor vehicles. Among females, neoplasms (almost all lung and cervix) (22.4%), circulatory system disorders (20.7%), and diabetes mellitus (17.2%) were the most common causes of death. When accidents are excluded, 59.4% of deaths were in persons with diabetes. Compared with Australia, mortality rates in almost all age groups were at least five times higher for males and females for a comparable period. Nauruan life expectancy (39.5 years for men and 48.5 years for women) is one of the lowest in the world. These data confirm the high mortality associated with diabetes mellitus in Nauruans as evidenced in earlier studies. Modernization of this society through the affluence acquired by the mining of phosphate has led to serious public health problems relating to non-communicable diseases so that the mortality trends now mirror those of developed societies.  相似文献   
102.
103.
104.
In the doubly-labelled water (2H2(18)O) method for the measurement of carbon dioxide production rate in man, single exponential disappearance curves for 2H2O and H2(18)O in body water are used; the precision with which the slopes and intercepts of the curves are estimated determines the precision of the estimate of carbon dioxide production rate. In studies with infants, and in computer simulations, the effect of different experimental regimes on the overall precision of the carbon dioxide production estimate was investigated. When the number of data points used was progressively reduced by shortening the total observation period from 7 d (about 3 biological half-lives for the isotopes) to 1 d there was a deleterious effect on precision and in the infants there was an upward bias in the values for carbon dioxide production. When the number of data points was reduced by removing points from the middle of the exponential curves with the maintenance of the 7-d experimental period, precision was also reduced but by less than in the former procedure and there were no consistent trends in the average values for carbon dioxide production.  相似文献   
105.
Recurrent erosion   总被引:1,自引:0,他引:1  
  相似文献   
106.
107.
108.
109.
Selective protection of the normal host tissues from the toxic effects of anticancer agents would allow the use of higher, probably more effective, doses of the drugs. It has been demonstrated that delayed high-dose uridine administration after 5-fluorouracil decreases the extent of myelosuppression and causes faster regeneration of the bone marrow. We studied the biochemical consequences of the gastrointestinal toxicity caused by 5-fluorouracil and the potential of high-dose uridine treatment to influence these adverse effects. 5-Fluorouracil caused dose-related decreases in the biochemical parameters (thymidine kinase, sucrase, maltase, alkaline phosphatase) selected as early markers of the impaired metabolic activity of the intestinal mucosa. The nadir of the biochemical changes was reached between 24 h and 72 h after 5-fluorouracil treatment, and complete regeneration of the mucosa took 6–7 days. Delayed high-dose uridine administration failed to mitigate the severity of the gastrointestinal damage that ensued after 5-fluorouracil treatment, but caused significantly earlier regeneration of the mucosa.  相似文献   
110.
The present study evaluated99mTc(V) DMSA as an agent for the visualization of inflammatory lesions in comparison to99mTc(HI) DMSA and99mTc-HIG. All three radiopharmaceuticals were prepared with commercial kits.99mTc(V) DMSA was prepared at neutral pH by the addition of first bicarbonate and then pertechnetate to the kit contents. The labeling efficiency was 99% as determined by ITLC. Abscesses were induced by i.m. injection of 50 μl turpentine into the right thighs of 36 Swiss albino mice. Six days later 3.7 MBq of each radiopharmaceutical was i.v. administered to 12 mice. The mice were sacrificed at 1,3,6 and 24 h later. Scintigrams were obtained with a gamma camera. The abscesses were better visualized on scintigrams with99mTc(V) DMSA compared to99mTc(III) DMSA, starting at 1 h. The animals were dissected and the organs were removed, weighed and the radioactivity determined with a gamma counter. The abscess to other tissue ratios were higher with99mTc(V) DMSA than the other radiopharmaceuticals. The max. abscess/muscle ratios were 9.46 ± 3.20 (24 h), 4.19 ± 1.39 (6 h) and 5.98 ± 1.17 (24 h) and max. abscess/blood ratios were 6.22 ± 1.41, 4.09 ± 0.84 and 0.914 ± 0.351 all at 24 h for99mTc(V) DMSA,99mTc(III) DMSA and99mTc-HIG, respectively. Experimental arthritis was produced in 6 New Zealand white rabbits by intra-articular injection of ovalbumin. Four days later 37 MBq of99mTc(V) DMSA and99mTc-HIG were each i.v. administered to 3 rabbits. Scintigrams obtained at 1, 3, 6, and 24 h clearly demonstrated arthritic joints. ROFs over arthritic joints were compared to contralateral normal joints (A/C). The max. A/C ratios were 2.10 ± 0.31 (3 h) and 2.92 ± 0.99 (24 h) for99mTc(V) DMSA and99mTc-HIG, respectively. Our results indicated the feasibility of imaging inflammatory lesions with99mTc(V) DMSA.  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