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   1754335篇
  免费   129279篇
  国内免费   4350篇
耳鼻咽喉   23928篇
儿科学   58713篇
妇产科学   50147篇
基础医学   251640篇
口腔科学   48990篇
临床医学   153984篇
内科学   345414篇
皮肤病学   38822篇
神经病学   139735篇
特种医学   69189篇
外国民族医学   622篇
外科学   268636篇
综合类   39983篇
一般理论   615篇
预防医学   133183篇
眼科学   40280篇
药学   126592篇
  4篇
中国医学   3539篇
肿瘤学   93948篇
  2018年   17989篇
  2017年   14094篇
  2016年   15656篇
  2015年   17706篇
  2014年   24632篇
  2013年   38114篇
  2012年   50482篇
  2011年   53716篇
  2010年   32448篇
  2009年   30672篇
  2008年   50908篇
  2007年   53880篇
  2006年   54576篇
  2005年   53007篇
  2004年   51162篇
  2003年   49369篇
  2002年   48171篇
  2001年   80314篇
  2000年   82485篇
  1999年   69802篇
  1998年   19575篇
  1997年   17772篇
  1996年   17770篇
  1995年   16802篇
  1994年   15799篇
  1993年   14859篇
  1992年   55572篇
  1991年   53774篇
  1990年   52877篇
  1989年   50899篇
  1988年   46698篇
  1987年   46501篇
  1986年   44068篇
  1985年   42311篇
  1984年   31681篇
  1983年   26968篇
  1982年   16202篇
  1981年   14391篇
  1979年   29424篇
  1978年   20953篇
  1977年   17771篇
  1976年   16742篇
  1975年   17961篇
  1974年   21619篇
  1973年   20802篇
  1972年   19384篇
  1971年   17969篇
  1970年   16987篇
  1969年   15882篇
  1968年   14861篇
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
991.
992.
Summary Cytosine arabinsodie (ara-C) and etoposide (VP-16) display synergy in the laboratory. Twenty-six patients participated in a phase I study of high-dose ara-C in combination with VP-16. The dose of VP-16 was held constant at 50 mg/m2 as an intermittent infusion over 33 h; escalating doses of ara-C were given as infusions during hours 9–12 and 21–24. Myelosuppression was the dose-limiting toxicity and occurred with doses considerably less than those expected from studies of the two drugs as single agents. The suggested initial doses for phase II trials with this schedule are 750 mg/m2×2 doses of ara-C and 50 mg/m2 of VP-16. Nonhematologic toxicity was minimal; therefore, further dose escalation is feasible in patients in whom myelosuppression is acceptable.Supported in part by grants from the National Cancer Institute (CA-12197 and CA-09422) and the American Cancer Society CF-85-182  相似文献   
993.
Rat brain hippocampal slices were incubated with or without the convulsant 4-aminopyridine (4-AP). From these slices a crude mitochondrial/synaptosomal membrane fraction was prepared and analyzed for endogenous protein phosphorylation. 4-AP (10(-5) M) stimulated the phosphorylation of a 50 kDa protein by 86%. The phosphorylation of this 50 kDa protein is Ca2+/calmodulin-dependent and we suggest that this protein is the lower molecular weight subunit of Ca2+/calmodulin-dependent protein kinase II (CaMK II).  相似文献   
994.
Retinitis pigmentosa (RP) is the most common hereditary dystrophic disease of the retina. About 10% of the affected families show the X-linked trait. The close link observed between the gene locus (RP2) and a polymorphic DNA marker (DXS7) on the proximal short arm of the X-chromosome permits an indirect genotype diagnosis and can be helpful in carrier detection and genetic counseling. A case is presented in which the carrier risk of a female consultant dropped from 50% a priori to less than 2% by the use of clinical findings and DNA analysis.  相似文献   
995.
996.
997.
In 1982 the levels of lead (Pb), cadmium (Cd), vanadium (V), copper (Cu), and selenium (Se) were determined in hair of 231 four- to five-year-old children. The objective was to explore the feasibility of using metal-in-hair levels in groups of children as an indicator of environmental pollution. The study was carried out in four areas, which were assumed to differ in ambient pollution by metals. A questionnaire on personal data, socioeconomic status, intake of beverages, and life-style was completed by the parents. The metal-in-hair levels covered a large range. The variables pertaining to location together with sex, presence of a garden, and drinking of coffee and/or tea explained 32% of the variance of Pb, 24% of the variance of Cd, and 21% of the variance of V. The total variance explained by all measured questionnaire items was at best 38%. The location was the most important factor. Cu and Se levels did not differ between the locations.  相似文献   
998.
Advances in Contraception - During 1983, 823 first trimester therapeutic abortions were performed at the University Hospital of Trondheim, Norway. Of these patients, 229 had an IUD inserted at the...  相似文献   
999.
Angiotensin-converting enzyme (ACE) was studied immunohistochemically in conjunctival biopsies from 6 patients with systemic sarcoidosis, 4 patients with posterior non-sarcoid uveitis and in specimens from 4 patients with chalazion of the eyelid. Specimens with sarcoid granulomas showed intense ACE-positive immunoreactivity in epitheloid cells of the granuloma, whereas chalazion granulomas did not contain ACE-immunoreactivity. There was no difference in staining patterns between specimens without granulomas. Thus immunohistochemical staining for ACE may be of help in differentiating conjunctival granulomatous tissue of a chalazion from sarcoid granuloma.  相似文献   
1000.
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