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   2220篇
  免费   5篇
  国内免费   2篇
电工技术   13篇
化学工业   367篇
金属工艺   103篇
机械仪表   43篇
建筑科学   13篇
矿业工程   23篇
能源动力   18篇
轻工业   47篇
水利工程   9篇
石油天然气   110篇
无线电   43篇
一般工业技术   349篇
冶金工业   1029篇
原子能技术   44篇
自动化技术   16篇
  2022年   20篇
  2021年   26篇
  2019年   20篇
  2018年   33篇
  2017年   35篇
  2016年   49篇
  2015年   26篇
  2014年   33篇
  2013年   28篇
  2012年   47篇
  2011年   47篇
  2010年   34篇
  2009年   45篇
  2008年   30篇
  2007年   33篇
  2006年   48篇
  2005年   31篇
  2004年   21篇
  2003年   25篇
  2002年   18篇
  2001年   22篇
  1999年   29篇
  1998年   271篇
  1997年   174篇
  1996年   121篇
  1995年   59篇
  1994年   52篇
  1993年   60篇
  1992年   22篇
  1991年   26篇
  1990年   29篇
  1989年   29篇
  1988年   23篇
  1987年   22篇
  1986年   29篇
  1985年   34篇
  1984年   19篇
  1982年   36篇
  1981年   22篇
  1980年   24篇
  1979年   24篇
  1978年   29篇
  1977年   56篇
  1976年   128篇
  1975年   23篇
  1974年   20篇
  1973年   22篇
  1972年   22篇
  1971年   19篇
  1969年   17篇
排序方式: 共有2227条查询结果,搜索用时 15 毫秒
1.
The effect of lomefloxacin was studied on mice with experimental infection due to Mycobacterium tuberculosis. The antibiotic was administered in doses of 100 and 200 mg/kg. It was shown that the use of lomefloxacin for a month provided a lower death rate of the animals with progressing acute generalized tuberculosis, a lower level of the lesions in the internal organs and a lower number of the Mycobacterium isolates from them. The efficacy of the treatment depended on the drug dose. When lomefloxacin was used in a dose of 200 mg/kg, the survival rate was much higher and the number of the epithelial unicellular granulomas in the tissue of the lung and spleen was markedly decreased while with the lower dose the indices did not differ from those in the control.  相似文献   
2.
Complexation of chitosan in aqueous solutions by low molecular weight electrolytes is one of the simplest methods for the preparation of aqueous chitosan dispersions. In this work, the influence of storage time, sulfate concentration, method of preparation and surfactant content on some properties of the resultant chitosan dispersions (turbidity, viscosity and zeta potential) was analyzed. Turbidimetry was adequate to monitor the formation of particles, while viscometry was suitable to monitor changes in the dispersing phase. An analysis of the properties of these systems, mainly in terms of particle–particle and macromolecule–macromolecule interactions was carried out. Copyright © 2004 Society of Chemical Industry  相似文献   
3.
4.
5.
The catalytic activity of a wide range of transition metal oxides in oxidation of sulphide ions by air in aqueous medium was studied. Some specific features of the reaction mechanism on some of the studied oxides were considered. The transition metal oxides are promising catalysts for practical application. Some of these oxides will allow the preparation of catalysts possessing activity comparable to that of the cobalt phthalocyanine based catalysts, popular in industrial practice.  相似文献   
6.
7.
The present study, based on 158 HIV seropositives and 167 HIV seronegatives, demonstrates that saliva collected with the Omni-SAL device and tested with GACELISA (an IgG antibody capture ELISA) is an effective non-invasive alternative to serum for anti-HIV IgG antibody screening. The study also shows that a conventional serum Western blot kit can be used, with slight modifications, for confirmatory testing of saliva specimens. Collecting saliva with the Omni-SAL device had a very good acceptance rate among Tanzanian subjects, and although this diagnostic method is not yet known by the general public, 65% of the study participants preferred to give saliva instead of blood for HIV testing.  相似文献   
8.
9.
A method is proposed for calculating the optimum density of lattice of blades of screw pump impeller that ensures, for a given cavitation margin (inlet pressure), the first critical condition on the partial cavitation characteristic of the pump. The equations obtained can be used also to calculate the permissible cavitation margin of screw centrifugal and screw mixed-flow pumps as well as of stand-alone screw impeller, provided the geometric and operating conditions of the screw are given. __________ Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 6, pp. 29–33, June, 2007.  相似文献   
10.
We compared the effects of an allergen challenge on airway responsiveness to methacholine, the slope of the dose-response curve (DRC) and post-methacholine fall in forced vital capacity (FVC) or forced expiratory volume in 1 s (FEV1)/FVC, and determined whether any changes in these parameters were related to the presence and magnitude of the late asthmatic response (LAR) in mild stable asthma. Twenty-three allergic asthmatic subjects had an allergen challenge, preceded and followed 24 (n = 12) and/or 48 (n = 22) h later by a methacholine challenge. Sixteen subjects had a dual asthmatic response to the allergen. On the post-allergen methacholine challenge, as compared with the pre-allergen test, differences in mean fall in FVC or FEV1/FVC at 20% fall in FEV1 and the slope of the DRC did not achieve statistical significance, even in the group with LAR, which showed a significant increase in airway responsiveness at 24 h. There was, however, a correlation between allergen-induced changes in PC20 and (1) the change in post-methacholine FVC fall in the LAR group at 48 h, and (2) the change in the slope of the DRC in the early-asthmatic-response group at 24 h. In conclusion, allergen-challenge-induced changes in airway response to methacholine are heterogeneous among asthmatic subjects and although it may increase airway responsiveness (PC20), particularly in late responders, it minimally affects the other aspects of airway response to methacholine, suggesting that a more powerful or sustained allergic stimulus is required to modify the latter.  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