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   2923265篇
  免费   226550篇
  国内免费   5528篇
耳鼻咽喉   39521篇
儿科学   96469篇
妇产科学   80860篇
基础医学   415695篇
口腔科学   86782篇
临床医学   264711篇
内科学   563976篇
皮肤病学   64358篇
神经病学   232313篇
特种医学   113452篇
外国民族医学   704篇
外科学   442601篇
综合类   70899篇
现状与发展   6篇
一般理论   1066篇
预防医学   225886篇
眼科学   69074篇
药学   218394篇
  9篇
中国医学   6409篇
肿瘤学   162158篇
  2018年   31141篇
  2017年   23919篇
  2016年   26380篇
  2015年   30191篇
  2014年   41896篇
  2013年   62727篇
  2012年   85820篇
  2011年   90512篇
  2010年   53532篇
  2009年   50335篇
  2008年   84957篇
  2007年   90173篇
  2006年   90993篇
  2005年   87821篇
  2004年   85591篇
  2003年   81689篇
  2002年   79320篇
  2001年   141920篇
  2000年   145971篇
  1999年   122303篇
  1998年   33453篇
  1997年   29698篇
  1996年   29621篇
  1995年   28568篇
  1994年   26645篇
  1993年   24764篇
  1992年   96942篇
  1991年   94149篇
  1990年   91265篇
  1989年   88043篇
  1988年   81166篇
  1987年   79580篇
  1986年   75597篇
  1985年   72593篇
  1984年   53954篇
  1983年   46341篇
  1982年   26807篇
  1981年   23972篇
  1979年   49955篇
  1978年   34479篇
  1977年   29337篇
  1976年   27555篇
  1975年   29116篇
  1974年   35507篇
  1973年   34085篇
  1972年   31497篇
  1971年   29536篇
  1970年   27345篇
  1969年   25617篇
  1968年   23590篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
953.
954.
High-dosage, tocolytic magnesium sulfate (MgSO4) administered to pregnant women during preterm labor can be toxic, and sometimes lethal, for their newborns (Cochrane Database of Systematic Reviews (relative mortality risk 2.82, 95% confidence interval 1.2-6.6)). Based on the results of the Magnesium and Neurologic Endpoints Trial and the work of many others, a unifying triangular concept is proposed to account for the increased prevalence of brain lesions, with their likely resultant mortality, in neonates and infants exposed to high-dose MgSO4 in the context of preterm labor. We review the evidence that: (1) elevated circulating levels of serum ionized magnesium occurring in mothers, and therefore in their babies, at the time of delivery are associated with subsequent neonatal intraventricular hemorrhage (IVH); (2) neonatal IVH is strongly associated with lenticulostriate vasculopathy (LSV), an unusual mineralizing lesion involving the thalami and basal ganglia of the neonate; and, (3) exposure to 50 g or more of tocolytic MgSO4 during preterm labor is associated with the development of LSV.  相似文献   
955.
Radiological lymphography presents drawbacks among which the risk of aggravation of the edema is most prominent. The authors report their experience with isotopic lymphography which best reproduces the physiological conditions of lymphatic drainage; it provides informations on the dermal or canalicular drainage route, the possible peripheral stasis or lymph leakage.  相似文献   
956.
A surgical technique was used to establish chronic intestinal ulcers in Sprague-Dawley rats. A 2-cm-long segment of the distal ileum was excised and left attached on the mesentery. The ileum was reanastomosed. The excluded ileal segment formed a 'cyst' of various sizes. Initially, the anastomoses healed well, but after 6-8 weeks para-anastomotic ulcers developed in more than 50% of the rats. Histopathology showed a chronic inflammatory reaction with a predominance of mononuclear cells and increased numbers of eosinophilic granulocytes. The surface of the ulcers was covered with bacteria. Penetrating ulcers with fistula formation occurred. It is concluded that this experimental model may be useful for time sequential studies of the development of chronic and ulcerative ileitis. It may also be used to study the effect of medical and surgical regimens for the treatment of non-specific chronic inflammatory bowel disease.  相似文献   
957.
In order to study the biological activity of endogenous digitalis-like substance (DLS) and Na-K-ATPase inhibitor (ATPI), human urine was partially purified and administered to rats, and its effects on the urinary volume, urinary Na excretion and blood pressure (BP) were determined. In addition, the effect on myocardial Na-K-ATPase activity was also measured. After the extraction of 40L of urine with a reversed phase cartridge column (S-fraction), 20 ml of chloroform was added and extraction was repeated. The chloroform layer was applied to an open silica gel column, and at a fraction with ethylacetate: methanol (60: 40, T-1 fraction), DLS and ATPI were eluted at the highest concentration. The water layer was treated with charcoal (D-1 fraction). The acute administration of K-1, T-1 fraction to rats in vivo caused significant rises in urinary volume, urinary Na excretion and BP. In chronic administration of K-1 fraction, urinary Na excretion was significantly elevated and myocardial Na-K-ATPase activity was also significantly suppressed. These results suggest that DLS and ATPI cause increase in the urinary volume and urinary Na excretion and also possess a hypertensive action; and moreover, these substance may affect the heart like cardiotonic steroids and regulate BP by increasing cardiac contractility.  相似文献   
958.
S Raam  D M Vrabel 《Clinical chemistry》1988,34(10):2053-2057
We present evidence to show that monoclonal antibodies to estrogen receptors (ER) in solid phase recognize the secondary estrogen binding sites with moderate to low affinity for estradiol (E2). An excellent quantitative agreement was found in five cytosols between the ER values obtained by the enzyme immunoassay (ER-EIA) and the amount of secondary estrogen binding sites measured by the assay involving dextran-coated charcoal (Clin Chem 1986;32:1496). The immunoreactive protein recognized by the antibody-coated beads, when allowed to react with ER(+) cytosols, is shown to bind [3H]estradiol only when the ligand concentration exceeds 8 nmol/L. Further biochemical and functional characterization of the immunoreactive protein is required to establish similarities/dissimilarities between this protein, high-affinity Type I ER sites, and the secondary sites such as Type II sites.  相似文献   
959.
960.
In einer clusteranalytischen Untersuchung mit 137 Patienten, die einen Parasuizid verübt hatten, wurden 6 Subgruppen unter Berücksichtigung der Klassifikationsvariable “suicide intent” isoliert. Es wurde die Hypothese geprüft, dass sich sowohl die Motivstrukturen als auch die Raten an wiederholten Parasuiziden in Abh?ngigkeit der Clusterl?sung bedeutsam voneinander unterscheiden. Die Ergebnisse unterstützen die Annahme einer zunehmenden Ausdifferenzierung der interpersonell orientierten Motivstrukturen mit sinkendem bzw. einer Einengung der Motivstruktur auf den Todeswunsch mit steigendem “suicide intent”. Es wurden folgende Subgruppen differenziert: eine Suizid-Hochrisikogruppe mit ausschlie?licher Todesintention und -motivation, 2 moderate Suizid-Risikogruppen mit hoher Todesintention und leichten Tendenzen zu interpersoneller Motivation, eine Subgruppe, gekennzeichnet durch eine manipulativ/strategisch orientierte Motivstruktur und auff?llig h?ufigen Parasuizidwiederholungen, eine Subgruppe mit vorrangig appellativ orientierten Motiven, Kontrollverlust und vergleichsweise seltenen Parasuizidwiederholungen und eine Subgruppe mit ambivalenter Motivstruktur (interpersonell und todesorientiert).  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