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   900201篇
  免费   74564篇
  国内免费   1939篇
耳鼻咽喉   13191篇
儿科学   25609篇
妇产科学   26028篇
基础医学   129740篇
口腔科学   26348篇
临床医学   80368篇
内科学   171436篇
皮肤病学   17422篇
神经病学   73652篇
特种医学   36650篇
外国民族医学   227篇
外科学   140928篇
综合类   25446篇
现状与发展   2篇
一般理论   304篇
预防医学   71294篇
眼科学   21511篇
药学   67534篇
中国医学   1617篇
肿瘤学   47397篇
  2018年   7982篇
  2015年   8294篇
  2014年   11957篇
  2013年   18120篇
  2012年   24519篇
  2011年   25591篇
  2010年   14923篇
  2009年   13974篇
  2008年   24271篇
  2007年   26329篇
  2006年   26227篇
  2005年   25825篇
  2004年   25364篇
  2003年   24320篇
  2002年   23386篇
  2001年   36991篇
  2000年   37728篇
  1999年   31999篇
  1998年   9715篇
  1997年   8966篇
  1996年   8860篇
  1995年   8388篇
  1994年   8081篇
  1992年   27483篇
  1991年   26950篇
  1990年   26392篇
  1989年   25457篇
  1988年   24007篇
  1987年   23553篇
  1986年   22411篇
  1985年   21730篇
  1984年   16920篇
  1983年   14455篇
  1982年   9153篇
  1981年   8476篇
  1980年   7943篇
  1979年   17243篇
  1978年   12501篇
  1977年   10507篇
  1976年   9651篇
  1975年   10434篇
  1974年   12974篇
  1973年   12458篇
  1972年   11819篇
  1971年   10939篇
  1970年   10450篇
  1969年   10139篇
  1968年   9135篇
  1967年   8438篇
  1966年   7839篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
The administration of prophylactic antibiotics in surgery is appropriate for many patients. Data have shown extending the duration of prophylaxis beyond 48 hours does not lower the rate of postoperative-infection. The purpose of this project was to concurrently assess the duration of prophylactic antibiotic use. A total of 95 patients were monitored over 3 weeks. Eighty patients (84.2%) received antimicrobial therapy. In 23 of these patients (28.75%) the duration of antibiotic administration was longer than 2 days without clinical or microbiological evidence of infection. In 5 other patients only postoperative antibiotics were prescribed. The cost difference between the actual duration of antibiotic administration and 2 days of the same regimen was +1,364.58. Extrapolating for one year, it can be estimated that antibiotic costs could be reduced about +23,600. Pharmacists can focus on the duration of antibiotic prophylaxis as a cost containment measure.  相似文献   
93.
The percentage uptake of [123I]metaiodobenzylguanidine (MIBG) by tumors of the paraganglion system is compared with the number of neurosecretory granules (assessed by both light and electron microscopy) in the subsequently resected tumors in six patients. Iodine-123 MIBG was injected intravenously; the tumor uptake of [123I]MIBG varied between 0.001% and 0.14% of the injected dose per gram of tumor tissue at 22 hr. The number of neurosecretory granules in tissue sections was scored on a scale of I-III. A direct proportional correlation was found between the percentage uptake of [123I]MIBG by the tumor and the number of neurosecretory granules in the tissue sections but not with plasma or urinary catecholamines. This technique for imaging reflects the storage status of the tumor better than plasma and urinary catecholamine measurements.  相似文献   
94.
95.
96.
Abstract A high frequency of serum complement component C4A deficiency may explain the higher prevalence and greater severity of systemic lupus erythematosus reported in Australian Aborigines. Inherited deficiencies of serum complement components C4A, C4B, and C2 were examined in two Australian Aboriginal populations from Darwin and Alice Springs and compared with the prevalence of complement deficiencies in white Australian blood donors. The frequency of C4A deficiency alleles was 29% in Darwin Aborigines compared with 12% in Alice Springs and 17% in Canberra blood donors. Partial C4B deficiency was also higher in Darwin Aborigines than in the other populations. Inherited deficiency of serum complement component C2 was not observed.  相似文献   
97.
98.
99.
Using cortical cups in chloralose-urethanized rats, the in vivo release of cholecystokinin-like immunoreactivity (CCK-LI) from cerebral cortex was examined. Resting levels of cholecystokinin-like immunoreactivity ranged from 20 to 30 pg/20 min sample. The addition of potassium (40 mM) in excess, resulted in a highly significant elevation in the levels of CCK-LI in the cortical superfusate. Deletion of calcium and the substitution of cobalt (10 mM), resulted in a significant reduction in both resting release and the release otherwise evoked by the addition of potassium. Focal electrical stimulation of the cortex (20 Hz), resulted in a significant (1.9 +/- 0.2-fold, n = 8) increase in the levels of CCK-LI. The addition of glutamate (10(-6)-10(-4) M) of kainic acid (10(-8)-10(-6) M), also resulted in significant elevations in the levels of CCK-LI. The co-administration of a putative glutamate receptor antagonist, kynurenic acid (10(-4) M) resulted in a significant reduction in the levels of release otherwise evoked by the addition of glutamate, but not by electrical stimulation. The addition of GABA (10(-5)-10(-3) M) resulted in a dose-dependent decrease in the resting release of CCK-LI, and the release evoked by glutamate. Picrotoxin (10(-6)-10(-4) M), resulted in a highly significant increase in the levels of CCK-LI in the cortical effluent. These results are consistent with a tonic GABAergic inhibition of CCK-releasing neurons. The treatment of the animal with diazepam (30 mg/kg, i.p.) also resulted in a significant reduction in resting release and the release otherwise evoked by focal cortical stimulation.  相似文献   
100.
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