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   528032篇
  免费   5107篇
  国内免费   928篇
电工技术   9647篇
综合类   640篇
化学工业   82072篇
金属工艺   23954篇
机械仪表   17740篇
建筑科学   11563篇
矿业工程   4428篇
能源动力   11714篇
轻工业   38646篇
水利工程   6305篇
石油天然气   15300篇
武器工业   34篇
无线电   56409篇
一般工业技术   113719篇
冶金工业   84902篇
原子能技术   15603篇
自动化技术   41391篇
  2021年   4640篇
  2019年   4496篇
  2018年   8317篇
  2017年   8449篇
  2016年   8885篇
  2015年   5198篇
  2014年   9089篇
  2013年   22845篇
  2012年   13691篇
  2011年   17820篇
  2010年   14225篇
  2009年   16167篇
  2008年   16653篇
  2007年   16343篇
  2006年   13958篇
  2005年   12659篇
  2004年   12469篇
  2003年   12115篇
  2002年   11782篇
  2001年   11832篇
  2000年   11410篇
  1999年   11157篇
  1998年   23685篇
  1997年   17772篇
  1996年   13844篇
  1995年   11007篇
  1994年   10104篇
  1993年   10057篇
  1992年   8097篇
  1991年   8010篇
  1990年   8000篇
  1989年   7785篇
  1988年   7529篇
  1987年   6807篇
  1986年   6832篇
  1985年   7692篇
  1984年   7181篇
  1983年   6847篇
  1982年   6253篇
  1981年   6484篇
  1980年   6207篇
  1979年   6332篇
  1978年   6372篇
  1977年   6944篇
  1976年   8428篇
  1975年   5702篇
  1974年   5663篇
  1973年   5725篇
  1972年   4968篇
  1971年   4504篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
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   
92.
It is not known whether impaired hematopoiesis noted during human immunodeficiency virus (HIV) infection results from infection of stem/progenitor cells or of cells of the bone marrow microenvironment. Normal adherent primary stromal layers were exposed to HIV to determine which of this mixture of endothelial cells, fibroblasts, and macrophages are susceptible to the virus. Viral p24 in supernatants was noted with monocytotropic HIV-1Ada, HIV-1Ba-L, and HIV-1JR-FL but not with lymphotropic HIV-1LAI nor HIV-1MN strain, and only stromal macrophages expressed the viral antigens. Coculture of the layers with PHA-activated normal lymphocytes failed to rescue lymphotropic virus. No p24 was produced when macrophage-depleted stromal cells were exposed to either HIV-1Ba-L or HIV-1LAI; proviral DNA was then amplified by PCR in cells exposed to either virus, though coculture with lymphocytes rescued only HIV-1Ba-L. Altogether, these data indicate that macrophages are the major targets of HIV in cultured stromal layers. As virus replication in macrophages did not affect the profile of major cytokines involved in regulating hematopoiesis, HIV infection could alter hematopoiesis by other as yet unspecified mechanisms.  相似文献   
93.
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   
94.
Given the enormous size of the genome and that there are potentially many other types of measurements we need to do to understand it, it has become necessary to pick and choose one's targets to measure because it is still impossible to evaluate the entire genome all at once. What has emerged is a need to have rapidly customizable microarrays. There are two dominant methods to accomplish custom microarray synthesis, Affymetrix-like microarrays manufactured using light projection rather than semiconductor-like masks used by Affymetrix to mass manufacture their GeneChip/sup TM/ arrays now, or the ink-jet printing method employed by Agilent. The manufacture of these custom Affymetrix-like microarrays can now be done on a digital optical chemistry (DOC) machine developed at the University of Texas Southwestern Medical Center, and this method offers much higher feature numbers and feature density than is possible with ink-jet printed arrays. On a microarray, each feature contains a single genetic measurement. The initial DOC prototype has been described in several publications, but that has now led to a second-generation machine. This machine reliably produces a number of arrays daily, has been deployed against a number of biomedical questions, is being used in new ways and has also led to a number of spin-off technologies.  相似文献   
95.
96.
97.
Functional Properties and Food Applications of Rapeseed Protein Concentrate   总被引:1,自引:0,他引:1  
Rapeseed protein concentrate (RC), prepared with 2% hexameta-phosphate, was tested for its functionality and performance in some foods. The RC had good nitrogen solubility, fat absorption, emulsification, and whipping capacities but poor water absorption and gelling properties. It increased the emulsion stability, and protein but lowered the fat content of wieners. It also increased the cooking yield, reduced the shrinkage and tenderized meat patties. Results were similar to soybean isolate except for the poorer color and flavor. The cooking yield of RC supplemented wieners was less than the all-meat control and soybean-supplemented wieners. A 9% RC dispersion mixed with an equal volume of eggwhite produced a meringue of comparable stability and texture to that of eggwhite alone.  相似文献   
98.
99.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989.  相似文献   
100.
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989.  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