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   251802篇
  免费   1818篇
  国内免费   267篇
电工技术   4053篇
综合类   93篇
化学工业   40771篇
金属工艺   15193篇
机械仪表   10117篇
建筑科学   4268篇
矿业工程   3769篇
能源动力   3916篇
轻工业   10200篇
水利工程   4109篇
石油天然气   13016篇
武器工业   28篇
无线电   20301篇
一般工业技术   63195篇
冶金工业   32896篇
原子能技术   11141篇
自动化技术   16821篇
  2021年   2801篇
  2019年   2771篇
  2018年   5506篇
  2017年   5805篇
  2016年   6146篇
  2015年   3132篇
  2014年   5417篇
  2013年   10289篇
  2012年   7485篇
  2011年   9094篇
  2010年   7433篇
  2009年   8218篇
  2008年   8308篇
  2007年   7984篇
  2006年   6428篇
  2005年   5621篇
  2004年   5546篇
  2003年   5357篇
  2002年   5186篇
  2001年   4983篇
  2000年   4969篇
  1999年   4293篇
  1998年   7438篇
  1997年   5985篇
  1996年   4535篇
  1995年   3729篇
  1994年   3470篇
  1993年   3673篇
  1992年   3236篇
  1991年   3381篇
  1990年   3501篇
  1989年   3379篇
  1988年   3279篇
  1987年   3272篇
  1986年   3163篇
  1985年   3321篇
  1984年   3255篇
  1983年   3153篇
  1982年   3001篇
  1981年   3049篇
  1980年   3074篇
  1979年   3258篇
  1978年   3491篇
  1977年   3467篇
  1976年   3932篇
  1975年   3212篇
  1974年   3294篇
  1973年   3343篇
  1972年   2988篇
  1971年   2754篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Several in vivo and in vitro methods for monitoring immunological properties of two allergoids obtained by formaldehyde treatment of ovalbumin (OA) were developed. The calculated molecular weight of allergoids was 80 kD (OA-F1) and 165 kD (OA-F2), respectively. The allergenic activity in vitro of allergoids in mast-cell histamine release assay was 1000 times lower than of OA. Both allergoids showed reduced ability to induce passive cutaneous anaphylaxis in the Sprague-Dawley rats or systemic anaphylaxis in Dunkin-Harley guinea-pigs. The ability of OA and allergoids to bind to the OA-specific IgE antibodies was measured in vivo by the inhibition of passive cutaneous anaphylaxis (PCA-inhibition). Allergoid binding to IgE was 51-66% lower than the native allergen. Moreover, the avidity of OA-specific IgG antibodies, measured by ELISA-inhibition, for allergoids and allergen was of the same order. Allergoids induced a different pattern of humoral immune response from that, induced by the native allergen. Thus, after immunization of BALB/c mouse, both allergoids induced a higher production of IgG and a lower production of IgE than OA, only OA-F2 induced a lower production of IgG1. The differences in the IgA response to the immunogens was not significant. Delayed hypersensitivity studies in the BALB/c mouse showed that allergoids were 5- to 12-times less effective in inducing a cell-mediated immune response than OA. The present study provides a battery of immunological methods for preclinical testing of modified allergens.  相似文献   
42.
The effectiveness of the hybrid system sonication followed by wet oxidation (SONIWO) to treat otherwise refractory waste has been demonstrated. In such a hybrid system homogeneous CuSO4 catalyst was found to be very efficient.  相似文献   
43.
The technological process of cold forging applied for the first time in the production of the casing of the internal joint with races is described. The process operations of cold forging and the annealing and carburizing regimes for this part me described.  相似文献   
44.
A method is considered for increasing the immunity from interference of broadband systems for measuring and transmitting information. It is based on utilizing nonlinear methods to process spread-spectrum signals. The possibility is investigated of using a quasioptimal receiving device which can be implemented in practice. It is shown that the proposed method makes it possible to solve the rejection problem at the physical level. Translated from Izmeritel'naya Tekhnika, No. 11, pp. 13–15, November, 1996.  相似文献   
45.
46.
47.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989.  相似文献   
48.
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989.  相似文献   
49.
50.
A method for fabricating single crystal blades that combines the techniques of seed crystals and selection is suggested. The method realizes the advantages of both techniques, i.e., the high structural perfection and the possibility of fabricating single crystals with specified spatial orientation. Metallographic and x-ray diffraction analyses are used to study the processes of nucleation of the single crystal structure of blade castings fabricated from high-temperature nickel alloys by the method of selection and seed crystals. A commercial process for fabricating cast single crystal turbine blades by the new method is suggested.  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