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   2263篇
  免费   229篇
  国内免费   31篇
耳鼻咽喉   15篇
儿科学   147篇
妇产科学   65篇
基础医学   269篇
口腔科学   38篇
临床医学   319篇
内科学   342篇
皮肤病学   39篇
神经病学   200篇
特种医学   193篇
外科学   231篇
综合类   74篇
一般理论   1篇
预防医学   274篇
眼科学   11篇
药学   185篇
中国医学   1篇
肿瘤学   119篇
  2022年   18篇
  2021年   46篇
  2020年   36篇
  2019年   45篇
  2018年   51篇
  2017年   36篇
  2016年   40篇
  2015年   47篇
  2014年   62篇
  2013年   83篇
  2012年   88篇
  2011年   92篇
  2010年   53篇
  2009年   62篇
  2008年   82篇
  2007年   98篇
  2006年   72篇
  2005年   88篇
  2004年   70篇
  2003年   63篇
  2002年   61篇
  2001年   61篇
  2000年   67篇
  1999年   59篇
  1998年   66篇
  1997年   58篇
  1996年   62篇
  1995年   54篇
  1994年   35篇
  1993年   42篇
  1992年   46篇
  1991年   37篇
  1990年   31篇
  1989年   49篇
  1988年   42篇
  1987年   25篇
  1986年   31篇
  1985年   50篇
  1984年   39篇
  1982年   19篇
  1981年   19篇
  1979年   19篇
  1977年   22篇
  1975年   17篇
  1971年   19篇
  1970年   21篇
  1969年   18篇
  1968年   19篇
  1966年   17篇
  1965年   20篇
排序方式: 共有2523条查询结果,搜索用时 15 毫秒
11.
The management of patients with asymptomatic hyperparathyroidism remains controversial. This study examined the extent to which the presence of prospect of bone disease should influence treatment. Bone mineral content (BMC) of the distal forearm was measured by single photon absorptiometry in 67 patients with mild hyperparathyroidism. Twenty-six patients treated surgically and 17 managed conservatively were reviewed regularly for up to 4 years. Eighty per cent of patients had a baseline fat-corrected BMC within the local reference interval for age and sex, but about 75 per cent of values fell below the mean. BMC at the 'distal' site of the surgically treated patients improved or stabilized, but a continuing decline was seen in the patients managed conservatively (P less than 0.01). Differences were small and concern about future osteoporotic fracture should seldom be a major factor in making decisions about surgical correction of mild hyperparathyroidism.  相似文献   
12.
Olson  MA; Becker  GJ 《Radiology》1986,159(1):25-26
An anomalous pulmonary vein draining into the subdiaphragmatic inferior vena cava was initially demonstrated on computed tomographic (CT) scans. The diagnosis of scimitar syndrome was confirmed with digital subtraction angiography. In retrospect, the anomalous vein and dextroposition of the heart were shown on chest radiographs.  相似文献   
13.
14.
15.
One-hundred and six male children aged 6-23 months with a history of acute watery diarrhoea of less than 72 h duration were randomized to receive either folic acid in a dose of 5 mg at 8-h intervals or placebo for 5 d. There were 54 children in the folic acid group and 52 in the placebo group. The admission characteristics were comparable between the two groups. No significant differences were observed in the intake of oral rehydration solution or stool output between the groups. The mean ± SD of total stool output (g kg−1) was 532 ± 476 vs 479 ± 354 and the duration (h) of diarrhoea was 108 ± 68 vs 103 ± 53 in the folic acid vs placebo group, respectively. The findings, therefore, should have a positive influence on preventing the inappropriate use of folic acid in acute diarrhoea.  相似文献   
16.
17.
Gramzinski  RA; Broze  GJ Jr; Carson  SD 《Blood》1989,73(4):983-989
Studies of proteins that inhibit tissue factor activity have generally been conducted using either an extracted tissue homogenate ("thromboplastin") or tissue factor protein reconstituted into phospholipid vesicles rather than with tissue factor expressed in cell membranes (its physiological environment). In the present study, a human fibroblast cell strain was used to evaluate the effects of lipoprotein associated coagulation inhibitor (LACI), placental anticoagulant protein (PAP), and apolipoprotein A-II (apo A-II) on human tissue factor in cell membranes. LACI was tested from 7.8 to 500 pmol/L on fibroblasts cultured at cell densities ranging from 3,500 to 9,925 cells/well, and caused a progressive inhibition of tissue factor activity. PAP was tested from 3.9 nmol/L to 1 mumol/L at cell densities ranging from 4,500 to 15,400 cells/well and caused up to 83% inhibition of tissue factor activity. Inhibition by these proteins appeared to be influenced by cell density as well as whether the cells were intact or disrupted. Apo A-II, up to 1 mumol/L, did not inhibit the tissue factor activity of intact or disrupted fibroblasts at any cell density examined even though it did inhibit the activity of tissue factor in phospholipid vesicles. Of these inhibitors of tissue factor-dependent activation of factor X, LACI was the most effective in suppressing the generation of factor Xa activity. The effects obtained with apo A-II are clearly dependent on the nature of the tissue factor preparation with which it is tested. The disparity between the inhibitory effect of apo A-II on the activity of tissue factor reconstituted into lipid vesicles and the absence of effect on the activity of tissue factor remaining in cell membranes serves to reemphasize the necessity of reexamining results obtained with model systems using as nearly physiological reagents as possible.  相似文献   
18.
A nontoxigenic strain of Vibrio cholerae O group 1 was isolated in Florida from the stool of a patient with severe diarrhea. The strain had the same hemolytic and unique phage-sensitivity pattern as all toxigenic isolates from recent cases of cholera in Texas and Louisiana. Identical strains were transiently isolated from sewerage systems in two other Florida communities, suggesting that multiple human infections had occurred. This is the first indication that V. cholerae O1 strains which do not produce cholera toxin may be able to cause gastrointestinal disease in humans. The identification of these strains also raises questions about the relationship between toxigenic and nontoxigenic strains of V. cholerae O1 along the Gulf Coast of the United States.  相似文献   
19.
20.
Human infections caused by coagulase-negative staphylococci have steadily increased in numbers and severity. Causes may be the use of artificial prostheses, immunocompromising chemotherapy and radiation therapy, and sophisticated surgical techniques, to name a few. Although the infectivity of coagulase-negative staphylococci as a group has been well documented for humans, attempts to study the pathogenesis of infections caused by individual species of coagulase-negative staphylococci have been hampered by the lack of an animal model that is not refractory to infection by these organisms. In the study reported here, a 2-day-old-mouse weight retardation test was used to assay the virulence of 60 clinical and reference strains of coagulase-negative staphylococci. These strains represented eight species of coagulase-negative staphylococci. The most virulent strains were demonstrated to be of the species Staphylococcus haemolyticus, S. saprophyticus, and S. epidermidis. The data further suggest that production of slime is a marker of virulence in S. epidermidis and that intraspecies differences in virulence occur.  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