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   1487196篇
  免费   95071篇
  国内免费   2044篇
耳鼻咽喉   19772篇
儿科学   49815篇
妇产科学   41570篇
基础医学   209985篇
口腔科学   37834篇
临床医学   122345篇
内科学   290384篇
皮肤病学   27839篇
神经病学   118042篇
特种医学   59734篇
外国民族医学   366篇
外科学   232611篇
综合类   29316篇
现状与发展   1篇
一般理论   306篇
预防医学   112867篇
眼科学   32453篇
药学   109003篇
  1篇
中国医学   3216篇
肿瘤学   86851篇
  2018年   35025篇
  2017年   27387篇
  2016年   31599篇
  2015年   13211篇
  2014年   17588篇
  2013年   26177篇
  2012年   41981篇
  2011年   58967篇
  2010年   41028篇
  2009年   32775篇
  2008年   57249篇
  2007年   63496篇
  2006年   40442篇
  2005年   41774篇
  2004年   41816篇
  2003年   42303篇
  2002年   39498篇
  2001年   58776篇
  2000年   60524篇
  1999年   51196篇
  1998年   14695篇
  1997年   13292篇
  1996年   13346篇
  1995年   12637篇
  1994年   12069篇
  1993年   11118篇
  1992年   41211篇
  1991年   40611篇
  1990年   40144篇
  1989年   38930篇
  1988年   36295篇
  1987年   35549篇
  1986年   33872篇
  1985年   32293篇
  1984年   24051篇
  1983年   20938篇
  1982年   12504篇
  1981年   10993篇
  1979年   22760篇
  1978年   15983篇
  1977年   13781篇
  1976年   13072篇
  1975年   14238篇
  1974年   16741篇
  1973年   16115篇
  1972年   15335篇
  1971年   14251篇
  1970年   13262篇
  1969年   12794篇
  1968年   12021篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
von Hippel-Lindau disease affecting 43 members of a single kindred   总被引:22,自引:0,他引:22  
We present a 6-generation kindred of over 221 members, 43 of whom were affected with von Hippel-Lindau (vHL) disease. Through a simple screening protocol, we diagnosed vHL retrospectively in 15 cases, and for the first time in 28, 11 of whom were presymptomatic. We found many complications of vHL in previously diagnosed relatives and in new cases. This study has demonstrated the utility and benefit of preventive surveillance in those known to have vHL, and of presymptomatic screening for affected relatives in families with vHL. The features of vHL were reviewed in our 43 cases and 511 cases from the medical literature. The patterns, frequencies, and ages of onset for each lesion were compared. Renal malignancies caused almost as much mortality in vHL as CNS malignancies. This family was exceptional for absence of pheochromocytoma and erythrocythemia, for more renal and pancreatic cysts and malignancies, and for slightly fewer eye or CNS lesions. Bilateral renal adenocarcinomata were found presymptomatically in five young subjects, who had bilateral nephrectomy and hemodialysis. Three survived long-term after renal transplants. Five relatives had pancreatic malignancies, which are definite although uncommon manifestations of vHL. Recommendations are made for family screening, which was economical and effective. Bayesian calculations help to predict risks for genetic counseling. The molecular basis of vHL may soon be found, since it has been linked to DNA markers on the short arm of chromosome 3.  相似文献   
992.
Prostaglandins (PGs) A1 and J2 were found to potently suppress the proliferation of human K562 erythroleukemia cells and to induce the synthesis of a 74-kDa protein (p74) that was identified as a heat shock protein related to the major 70-kDa heat shock protein group. p74 synthesis was stimulated at doses of PGA1 and PGJ2 that inhibited cell replication, and its accumulation ceased upon removal of the PG-induced proliferation block. PGs that did not affect K562 cell replication did not induce p74 synthesis. p74 was found to be localized mainly in the cytoplasm of PG-treated cells, but moderate amounts were found also in dense areas of the nucleus after PGJ2 treatment. p74 synthesis was not necessarily associated with cytotoxicity or with inhibition of cell protein synthesis. The results described support the hypothesis that synthesis of the 70-kDa heat shock proteins is associated with changes in cell proliferation. The observation that PGs can induce the synthesis of heat shock proteins expands our understanding of the mechanism of action of these compounds whose regulatory role is well known in many physiological phenomena, including the control of fever production.  相似文献   
993.
Histological sections of brain from patients showing evidence of advanced pathology of Alzheimer disease (AD) were examined for the presence of herpes simplex type-1 (HSV-1) nucleic acids by a sensitive in-situ hybridization technique. Samples from neurologically normal patients were examined in parallel. Sensitivity of the assay was verified by the detection of HSV-1 nucleic acids in neurons of trigeminal ganglia taken from cases of AD and normal controls. This indicated that the hybridization reaction was sufficiently sensitive to detect latent HSV-1 infections. Positive hybridization in the brain was only detected in a confirmed case of herpes simplex virus encephalitis. These results appear to confirm previous reports that HSV-1 infection is not directly involved in the pathology associated with AD.  相似文献   
994.
L G Strauss 《Der Radiologe》1989,29(7):318-321
Positron emission tomography with metabolically active substances is a noninvasive imaging modality to determine tumor metabolism. Quantification of tumor metabolism provides valuable information, e.g., for the differential diagnosis of malignancies. Radiolabeled therapeutic substances can be traced with PET. Measurement of fluorouracil metabolite concentrations provides data about the accumulation pattern of the cytostatic agent and allows assessment of the therapeutic outcome.  相似文献   
995.
996.
997.
998.
In the search for HLA-linked immune response genes that control susceptibility to tuberculosis, we performed HLA typing and measured antibody titers to well-defined Mycobacterium tuberculosis antigenic determinants in 101 patients with sputum smear-positive pulmonary tuberculosis and 64 healthy controls from Surabaya, Indonesia. HLA-DR2 and DQw1 were associated with sputum smear-positive pulmonary tuberculosis (attributable risk = 36% and 39%, respectively), while DQw3 was associated even more strongly with the control group (preventive fraction = 57%). Antibody titers to the TB71 and TB72 epitopes of the 38-kDa protein, present only on tubercle bacilli, were strongly associated with DR2 (Pcorr = .001 and .024, respectively). The association of both the disease and the antibody response to the 38-kDa antigen of M. tuberculosis with Class II HLA genes HLA-DR2 indicates that Ir-gene-mediated regulation of the immune response to this antigen may be of pathogenic significance for the development of sputum smear-positive tuberculosis.  相似文献   
999.
1000.
M E Astiz  E C Rackow  P Haydon  G Karras  M H Weil 《Chest》1989,96(2):363-366
Alterations in peripheral vascular tone are presumed to contribute to circulatory failure during severe sepsis. Decreased venous tone with venous pooling may decrease effective circulatory blood volume, while decreased arterial tone with redistribution of systemic blood may compromise tissue nutrient flow. We compared forearm arterial and venous tone and forearm blood flow in ten patients with and ten patients without sepsis. The FVT, MVC, and FBF were measured by air plethysmography. In the septic patients, MCV was 1.4 +/- 0.1 ml compared with 3.1 +/- 0.2 ml in nonseptic patients (p less than 0.01). The FVT was 13.4 +/- 1.0 mm Hg/ml in septic patients versus 7.0 +/- 0.5 mm Hg/ml in nonseptic patients (p less than 0.01). The ratio of FBF to cardiac output was 0.28 +/- 0.07 percent in septic patients and 0.31 +/- 0.07 percent in nonseptic patients. These data suggest that increased peripheral venous capacitance and redistribution of skeletal muscle blood flow are not present in patients with sepsis.  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