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   3214篇
  免费   20篇
  国内免费   7篇
电工技术   15篇
化学工业   161篇
金属工艺   18篇
机械仪表   13篇
建筑科学   39篇
能源动力   16篇
轻工业   44篇
水利工程   5篇
无线电   49篇
一般工业技术   123篇
冶金工业   2659篇
原子能技术   5篇
自动化技术   94篇
  2021年   16篇
  2020年   10篇
  2018年   13篇
  2017年   14篇
  2016年   11篇
  2015年   9篇
  2014年   21篇
  2013年   39篇
  2012年   23篇
  2011年   50篇
  2010年   27篇
  2009年   33篇
  2008年   22篇
  2007年   27篇
  2006年   37篇
  2005年   28篇
  2004年   16篇
  2003年   25篇
  2002年   18篇
  2001年   12篇
  2000年   12篇
  1999年   90篇
  1998年   717篇
  1997年   453篇
  1996年   287篇
  1995年   157篇
  1994年   138篇
  1993年   168篇
  1992年   25篇
  1991年   31篇
  1990年   32篇
  1989年   39篇
  1988年   30篇
  1987年   29篇
  1986年   26篇
  1985年   26篇
  1984年   9篇
  1983年   29篇
  1982年   28篇
  1981年   22篇
  1980年   37篇
  1979年   18篇
  1978年   20篇
  1977年   76篇
  1976年   162篇
  1975年   15篇
  1974年   9篇
  1972年   9篇
  1970年   9篇
  1955年   9篇
排序方式: 共有3241条查询结果,搜索用时 812 毫秒
41.
An original operation is proposed for localization of the diverticulum in the descending portion of the duodenum which excludes traumas of the pancreas. Clinical observations are described.  相似文献   
42.
OBJECTIVE: To assess the effect on various aspects of carbohydrate and lipid metabolism of administering a quick-release formulation of bromocriptine (Ergoset) to obese, nondiabetic, hyperinsulinemic women. RESEARCH DESIGN AND METHODS: Hourly concentrations of prolactin, glucose, insulin, free fatty acid (FFA), and triglyceride were measured for 24 h before and after approximately 8 weeks of treatment with Ergoset. In addition, fasting lipid and lipoprotein concentrations and the steady-state plasma glucose (SSPG) concentration in response to a continuous infusion of somatostatin, insulin, and glucose were determined before and after Ergoset administration. RESULTS: Circulating prolactin concentrations were dramatically decreased (P < 0.001) following treatment, associated with a significant fall (P < 0.05) in 24-h-long plasma glucose, FFA, and triglyceride concentrations. Neither circulating plasma insulin concentrations nor the ability of insulin to mediate glucose disposal changed with treatment. Finally, fasting total cholesterol fell (P < 0.05) and the ratio of total to HDL cholesterol decreased (P = 0.06) in association with Ergoset treatment. CONCLUSIONS: The fact that significant metabolic improvement was seen in the obese nondiabetic hyperinsulinemic women studied suggests that Ergoset could be of therapeutic benefit in clinical conditions of hyperglycemia and/or dyslipidemia.  相似文献   
43.
44.
45.
Six men were accidentally exposed to NO2 when they were changing a propeller using a gas burner in the poorly ventilated hold of a ship. All of them were admitted to hospital with shortness of breath and cough. Chest X-ray on admission revealed diffuse, patchy and infiltrative shadows, leading to the diagnosis of pulmonary edema in all five patients. Steroid therapy was effective and followed by a quick recovery in all patients. None developed third phase manifestations characterized pathologically by bronchiolitis obliterans.  相似文献   
46.
The authors report a case of pregnancy in a rudimentary horn diagnosed by laparotomy. The location could not be suspected by any clinical sign. This pregnancy stopped at 19 weeks of amenorrhoea. Any attempts of induction of labour failed. Laparotomy was necessary to assess the diagnosis and to allow the resection of the uterine horn. The authors present a review of literature.  相似文献   
47.
In the context of the radiation exposure of the Ukrainian population resulting from the Chernobyl accident, the quantification of the thyroid doses due to iodine incorporation is of special interest. This first part of a series of planned publications deals with the dose and risk estimation for Kiev citizens. Although these doses are expected to be considerably lower than those for some other regions of Ukraine, the investigations started with this population because the quantification of the thyroid doses due to iodine incorporation is of special interest. This first part of a series of planned publications deals with the dose and risk estimation for Kiev citizens. Although these doses are expected to be considerably lower than those for some other regions of Ukraine, the investigations started with this population because of the availability of rather reliable measurements and because of the size of this population. The methods developed allowed the estimation of individual thyroid doses. The average values of individual thyroid doses for five age groups (birth years 1983-1986, 1979-1982, 1975-1978, 1971-1974, and < 1971) are 104, 62, 19, 18, and 41 mGy, respectively. The collective thyroid doses were estimated as 83 x 10(3) person-Gy for those born before 1971 and as 38 x 10(3) person-Gy for younger inhabitants. The numbers of expected thyroid cancers in the whole Kiev population are 66 and 130, respectively.  相似文献   
48.
Infection by human immunodeficiency virus type 1 (HIV-1) is often complicated by a variety of neurological abnormalities. The most common clinical syndrome, termed acquired immunodeficiency syndrome (AIDS) dementia complex, presents as a subcortical dementia with cognitive, motor, and behavioral disturbances and is unique to HIV-1 infection. The pathogenesis of this syndrome is poorly understood but is believed to involve interactions among virally infected macrophages/microglia, astrocytes, and neurons. In this study, we show that exposure of primary rat and human astrocytes to heat-activated HIV-1 virions, or to eukaryotically expressed HIV-1 and HIV-2 envelope glycoproteins (gp120) stimulates amiloride-sensitive Na+/H+ antiport, potassium conductance, and glutamate efflux. These effects are blocked specifically by amiloride, an inhibitor of Na+/H+ antiport and by the selective removal of gp120 with immobilized monoclonal antibody. As a result of modulation of astrocytic function by gp120, the ensuing neuronal depolarization and glutamate exposure could activate both voltage-gated and N-methyl-D-aspartate-regulated Ca2+ channels, leading to increases in intraneuronal Ca2+ and neuronal death. These findings implicate the astrocyte directly in the pathogenesis of AIDS dementia complex.  相似文献   
49.
50.
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