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   613293篇
  免费   33768篇
  国内免费   614篇
耳鼻咽喉   7656篇
儿科学   20297篇
妇产科学   15004篇
基础医学   96262篇
口腔科学   15036篇
临床医学   50568篇
内科学   113818篇
皮肤病学   12624篇
神经病学   46132篇
特种医学   23017篇
外国民族医学   63篇
外科学   94596篇
综合类   9375篇
一般理论   118篇
预防医学   48146篇
眼科学   13124篇
药学   45502篇
中国医学   1011篇
肿瘤学   35326篇
  2018年   16295篇
  2017年   12961篇
  2016年   15355篇
  2015年   4896篇
  2014年   6367篇
  2013年   9823篇
  2012年   16001篇
  2011年   24345篇
  2010年   16306篇
  2009年   13814篇
  2008年   24273篇
  2007年   27772篇
  2006年   15169篇
  2005年   16344篇
  2004年   16662篇
  2003年   17385篇
  2002年   15956篇
  2001年   24385篇
  2000年   25623篇
  1999年   20763篇
  1998年   5629篇
  1997年   4977篇
  1996年   5206篇
  1995年   4787篇
  1994年   4504篇
  1992年   15864篇
  1991年   16454篇
  1990年   16558篇
  1989年   15921篇
  1988年   14691篇
  1987年   14548篇
  1986年   13705篇
  1985年   13091篇
  1984年   9700篇
  1983年   8321篇
  1982年   4651篇
  1979年   9520篇
  1978年   6922篇
  1977年   5791篇
  1976年   5674篇
  1975年   6397篇
  1974年   7665篇
  1973年   7138篇
  1972年   6960篇
  1971年   6685篇
  1970年   6200篇
  1969年   5926篇
  1968年   5583篇
  1967年   5012篇
  1966年   4450篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
Membrane-bound CD14 acts as a receptor for lipopolysaccharide (LPS) on monocytes/macrophages and neutrophils. Studies have suggested that the activation of monocytes/macrophages by the binding of LPS to membrane-bound CD14 may require the association of a signal-transducing molecule with membrane-bound CD14. The observation that non-CD14 expressing cells, such as endothelial cells, can nevertheless be activated by a complex of LPS and a soluble form of CD14 (sCD14) suggests that the receptor for this complex may be identical to the signal transducing molecule associated with membrane-bound CD14. The studies described show that two CD14-specific MoAb are able to block the LPS-induced activation of endothelial cells but do not affect the response of monocytes to LPS. This suggests that the interaction of the sCD14:LPS complex with endothelial cells is distinct from the interaction of membrane-bound CD14 with its putative signal-transducing molecule.  相似文献   
56.
Palytoxin, a highly toxic natural product isolated from zoanthids of the genus Palythoa, is accumulated by a wide range of fishes and marine invertebrates used as food in the Indo-Pacific. It is responsible for many incidents of human morbidity and mortality. The toxin is a potent smooth muscle spasmogen. The cause of the contraction of smooth muscle is unclear, but recent work strongly suggests that it is primarily initiated by the release of neurotransmitters from the motor innervation of the smooth muscle. We show here that palytoxin caused the swelling of the muscle cells and some internal organelles of the anococcygeus muscle of the rat, but no substantial structural damage to the tissue. Axons and Schwann cells were also swollen but the most dramatic feature was the depletion of synaptic vesicles from putative release sites in the axons. Some axons were physically damaged following exposure to the toxin, but this was relatively uncommon (<10% of all axons studied). In the majority of axons there was no damage to nerve terminal membranes, but there was damage to mitochondria. The depletion of vesicles involved all types – clear, dense-cored, large and small. Our observations and pharmacological data gathered elsewhere, provide a neuropathological basis for the spasmogenic activity of palytoxin.  相似文献   
57.
Factors associated with levels of physical activity at work and during leisure time were analyzed among 577 subjects who had been selected as population controls for a case-control study by random selection from telephone directories. The intensity of physical activity at work was inversely associated with body mass index, the proportion of professionals & managers, consumption of western style breakfast, coffee, butter/margarine, and whisky; and positively associated with rice intake. Frequency of physical activities during leisure time was positively associated with consumption of vegetables, fruits, mushrooms, milk, cheese and coffee, and moderation in eating; and inversely associated with rice intake and the prevalence of gastrointestinal symptoms and medication. The association of physical activity with these factors should be considered in studying its relationship to disease risk.  相似文献   
58.
This paper examines the effect of patient age, tumour grade and extent of surgery on the outcome of treatment of 278 patients with high grade malignant gliomas referred to the Queensland Radium Institute between 1980 and 1987. The aim was to determine whether the extent of surgical resection alters survival rates. The extent of surgery had no effect on survival except for those patients with grade 3 tumours in whom a total excision was possible. Those in whom only a biopsy was done did not have a worse prognosis. Grading was found to be of importance, as patients with grade 3 tumours had a better survival than those with grade 4 tumours. In grade 4 tumours, those under 30 years of age had a better survival than those over 30 years, whereas with grade 3 tumours there was a gradation of age effect (under 40 years best, then 40–49 years, and those 50 years and over doing worst).  相似文献   
59.
60.
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