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   241410篇
  免费   2632篇
  国内免费   427篇
电工技术   4292篇
综合类   257篇
化学工业   39412篇
金属工艺   9383篇
机械仪表   7398篇
建筑科学   5463篇
矿业工程   1391篇
能源动力   5162篇
轻工业   24826篇
水利工程   2477篇
石油天然气   5092篇
武器工业   32篇
无线电   25048篇
一般工业技术   44793篇
冶金工业   45389篇
原子能技术   5950篇
自动化技术   18104篇
  2021年   2108篇
  2019年   2017篇
  2018年   3490篇
  2017年   3426篇
  2016年   3689篇
  2015年   2236篇
  2014年   3901篇
  2013年   10189篇
  2012年   6152篇
  2011年   8316篇
  2010年   6560篇
  2009年   7239篇
  2008年   7589篇
  2007年   7721篇
  2006年   6891篇
  2005年   6051篇
  2004年   5820篇
  2003年   5600篇
  2002年   5676篇
  2001年   5563篇
  2000年   5385篇
  1999年   5303篇
  1998年   12593篇
  1997年   8912篇
  1996年   6860篇
  1995年   5336篇
  1994年   4739篇
  1993年   4626篇
  1992年   3669篇
  1991年   3389篇
  1990年   3594篇
  1989年   3473篇
  1988年   3303篇
  1987年   2895篇
  1986年   2932篇
  1985年   3373篇
  1984年   3219篇
  1983年   2892篇
  1982年   2738篇
  1981年   2822篇
  1980年   2721篇
  1979年   2625篇
  1978年   2684篇
  1977年   2948篇
  1976年   3808篇
  1975年   2368篇
  1974年   2242篇
  1973年   2376篇
  1972年   1970篇
  1971年   1858篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
871.
872.
873.
874.
Nine children of the ALL-REZ BFM 87 and 90 trial received L-Asparginase (L-ASP) as a continuous infusion for 48-72 hs (i.e. 25 therapy cycles). Seven patients had had an allergic reaction towards an i.m. application (i.m., 29 therapy cycles). Two further patients got L-ASP initially as continuous infusion. The i.m. applications were carried out 19 times with Erwinia and 10 times with E. coli-Asparaginase, the continuous infusions 15 times with Erwinia and 10 times with E. coli-Asparaginase. In case of four patients continuous infusions of the same L-ASP type (E. coli or Erwinia) was well tolerated, after there had been an allergic reaction after i.m. application. Allergic reactions after i.m. application occurred during 10 courses as local painful erythema, during five courses as urticaria, during four courses as a general exanthema during one course as difficult breathing and during a further course as drop in blood pressure. After continuous infusion of L-ASP urticaria and difficult breathing occurred once and a transient exanthema two times. There was no anaphylactic reaction in any case. These data show that i.m. application of L-ASP causes no life-threatening side effects but allergic reactions (local pain and swelling) which clearly impaired general condition. Continuous infusion is a pharmacologically equivalent alternative with less impairment of the patients' general condition.  相似文献   
875.
The effects of the plasma etching process induced gate oxide damages on device's low frequency noise behavior are investigated on MOSFET's fabricated with different field plate perimeter to gate area ratio antennas. Abnormal 1/f noise spectrum with a shoulder centered in the frequency range of 100 and to 1 kHz was frequently observed in small geometry devices, and it is attributable to a nonuniform distribution of oxide traps induced by plasma etching process  相似文献   
876.
Familial dysautonomia (FD), a recessively inherited disease, has been mapped to chromosome 9q31. Highly polymorphic dinucleotide repeat markers flanking the genetic locus and at the same genetic location have been identified. We describe the prenatal diagnosis of FD using linkage and linkage disequilibrium analyses with these markers. Twelve families were analysed for informativeness and of these, seven went on to have prenatal testing (a total of eight fetuses tested). All of these fetuses were predicted to be heterozygous unaffected (FD carriers). Seven fetuses have come to term and are normal. In the absence of a recombinant proband, a panel of three proximal and three distal markers is sufficient to provide informative flanking markers and an 87-96 per cent likelihood of a highly predictive test. In an additional family at 1:4 risk for FD, no DNA was available from the propositus. This family was analysed using linkage disequilibrium to the #18 allele of the tightly linked marker D9S58 in conjunction with linkage analysis using data from two unaffected children. Prenatal diagnosis in this family indicated an affected fetus.  相似文献   
877.
878.
879.
880.
Cerebral lateralization in visual perception was investigated in 9 severe stuttering, 11 mild stuttering and 48 fluent speakers. The subjects were asked to identify words presented in the left or right visual field for 20 ms. Children responded by pointing to the exposed test word on a response card which contained four different words. Errors committed in the left and right visual fields were analyzed. The data showed a left hemisphere superiority in the processing of words in both the mild stutterers and the fluent speakers, but a right hemisphere advantage in the severe stutterers. The results suggest a close relationship between the severity of stuttering and functional brain organization.  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