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   1682829篇
  免费   118797篇
  国内免费   2535篇
耳鼻咽喉   23977篇
儿科学   55770篇
妇产科学   48704篇
基础医学   252329篇
口腔科学   47670篇
临床医学   143239篇
内科学   324191篇
皮肤病学   36428篇
神经病学   128347篇
特种医学   64652篇
外国民族医学   426篇
外科学   258317篇
综合类   33667篇
现状与发展   1篇
一般理论   407篇
预防医学   124026篇
眼科学   39141篇
药学   129280篇
  1篇
中国医学   3239篇
肿瘤学   90349篇
  2018年   15634篇
  2015年   15133篇
  2014年   20875篇
  2013年   31987篇
  2012年   43749篇
  2011年   47208篇
  2010年   27804篇
  2009年   26233篇
  2008年   45665篇
  2007年   49435篇
  2006年   50233篇
  2005年   49055篇
  2004年   47358篇
  2003年   45841篇
  2002年   45265篇
  2001年   76456篇
  2000年   78782篇
  1999年   66468篇
  1998年   18507篇
  1997年   16460篇
  1996年   16947篇
  1995年   15926篇
  1994年   15049篇
  1993年   14070篇
  1992年   53056篇
  1991年   52921篇
  1990年   52578篇
  1989年   50958篇
  1988年   47463篇
  1987年   46577篇
  1986年   44304篇
  1985年   42360篇
  1984年   31460篇
  1983年   27304篇
  1982年   15947篇
  1981年   14276篇
  1979年   30146篇
  1978年   21382篇
  1977年   18371篇
  1976年   17465篇
  1975年   19343篇
  1974年   22878篇
  1973年   21919篇
  1972年   20956篇
  1971年   19646篇
  1970年   18324篇
  1969年   17674篇
  1968年   16612篇
  1967年   14702篇
  1966年   13446篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Others have reported that spinal cord transection non-uniformly affects the activities of the cardiac, renal and splenic nerves. We were unable to confirm this finding while recording the wide band (1-1000 Hz) discharges of these sympathetic nerves in baroreceptor-denervated, chloralose-anesthetized cats. Most of the power in nerve discharges was below 6 Hz. There was high coherence between the low frequency discharges of different nerves, and power below 15 Hz was essentially eliminated by spinal transection. Evidence is presented that the disparities between this and past studies are, in part, due to the use of a 30-Hz high-pass filter in the earlier studies.  相似文献   
992.
993.
994.
995.
Encephalo-myelo-radiculo-ganglionitis presenting as pandysautonomia   总被引:2,自引:0,他引:2  
A 68-year-old man developed pandysautonomia with severe orthostatic dysfunction, fixed heart rate, low serum levels of norepinephrine and epinephrine, absent sympathetic skin responses, and pupillary abnormalities. CSF protein was 92 mg/dl. In spite of a good recovery following corticosteroid administration, a relapse occurred, with accompanying sensory symptoms confined to both arms. Fatal sudden cardiac arrest occurred after 4 months. Autopsy revealed numerous lymphocytic infiltrates, predominantly in autonomic and sensory ganglia and, to a lesser extent, in the nerve roots, spinal cord, and brainstem without evidence for an underlying tumor. This case provides histopathologic evidence for an inflammatory etiology of panautonomic neuropathy in some patients.  相似文献   
996.
The ability of native and oxidized lipids and lipoproteins to stimulate production of reactive oxygen species (ROS; superoxide and hydrogen peroxide) by human blood monocytes has been studied in vitro. Neither native human low density lipoprotein (LDL), ''altered'' LDL (oxidized either by lipoxygenase, activated human monocytes or air) nor oxidized cholesterol had any significant effect on ROS production of monocytes. However, different oxidation products of a lipid emulsion (Lipofundin; largely consisting of linoleic acid oxidized either by lipoxygenase, Fe3+ or ultraviolet irradiation) greatly enhanced ROS production of monocytes. A hypothesis that activation of circulating leucocytes by oxidized fatty acids may generate oxidized plasma LDL, was tested in rabbits. Characteristics of LDL, separated from rabbit plasma 6 h after intravenous injection of an oxidized lipid emulsion, was compared to that of LDL isolated before the lipid treatment. Post-treatment LDL-fraction of plasma had increased lipid peroxide content and compared to the pretreatment LDL, caused a threefold increase in the incorporation of cholesterol into cultured (rat aortic) endothelial cells. The observed intense and lasting stimulation of monocytes by oxidized polyunsaturated fatty acids in vitro, and the generation of ''altered'' LDL by these oxidized lipids in vivo suggests a mechanism by which atherogenic oxidized LDL could form in the circulation.  相似文献   
997.
G Balogh 《Orvosi hetilap》1991,132(38):2075-2080
Experiences obtained with 400 cases of thoracal empyema are described. The fact that the rate of lethality was 18.7% until present points out to the severity of the disease. The semi-conservative therapeutical methods used by the author (drainage, drainage and pleura lavage, pleura lavage and thoracoscopy, balance drainage) are presented. With their sensibly more frequent use the rate of operation could be reduced by 8% (from 36.5% to 28.5%) and the lethality rate by 7.6% (from 18.7% to 11.1). Further improvement of the results may be expected of the increased number of early detection (basic care), concentration of empyemic patients in special institutes (departments, wards) and due to it of a more efficient special treatment of uniform contemplation.  相似文献   
998.
A simple gas chromatographic procedure has been developed for the determination of methyltestosterone in bulk powders and in tablets. Two new silyl ether derivatives of methyltestosterone have been prepared using dimethylethylsilylimidazole (DMESI) and dimethylisopropylsilylimidazole (DMiPSI). The method is accurate and selective for methyltestosterone within the concentration range 0.1-1.5 micrograms microliters-1.  相似文献   
999.
A combined LC/RIA procedure is described for the selective determination of dexamethasone (DEX) and its prodrug dexamethasone-21-isonicotinate (DIN) in plasma. The low affinity of the employed dexamethasone antiserum for DIN (cross-reactivity less than 0.5%) allowed the direct determination of DEX in plasma extracts. For the determination of DIN, both substances of interest were separated by LC, the DIN containing fraction was collected, hydrolysed and the generated DEX was consequently assayed by radioimmunoassay. The assay detection limits were 0.1 ng ml-1 for DEX and 0.75 ng ml-1 for DIN. For both substances, inter- and intra-day variabilities (RSDs) were 6 and 12%, respectively.  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