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   707篇
  免费   25篇
  国内免费   2篇
电工技术   7篇
化学工业   197篇
金属工艺   1篇
机械仪表   12篇
建筑科学   12篇
能源动力   23篇
轻工业   73篇
水利工程   2篇
石油天然气   1篇
无线电   68篇
一般工业技术   95篇
冶金工业   169篇
原子能技术   12篇
自动化技术   62篇
  2023年   5篇
  2022年   31篇
  2021年   21篇
  2020年   10篇
  2019年   13篇
  2018年   17篇
  2017年   16篇
  2016年   11篇
  2015年   13篇
  2014年   14篇
  2013年   32篇
  2012年   28篇
  2011年   24篇
  2010年   26篇
  2009年   25篇
  2008年   32篇
  2007年   21篇
  2006年   17篇
  2005年   17篇
  2004年   21篇
  2003年   25篇
  2002年   17篇
  2001年   18篇
  2000年   8篇
  1999年   6篇
  1998年   55篇
  1997年   33篇
  1996年   37篇
  1995年   20篇
  1994年   15篇
  1993年   10篇
  1992年   4篇
  1991年   3篇
  1990年   8篇
  1989年   5篇
  1985年   4篇
  1984年   3篇
  1983年   4篇
  1981年   7篇
  1980年   4篇
  1979年   3篇
  1978年   2篇
  1977年   7篇
  1976年   11篇
  1975年   2篇
  1974年   2篇
  1972年   3篇
  1971年   4篇
  1967年   3篇
  1965年   5篇
排序方式: 共有734条查询结果,搜索用时 15 毫秒
1.
Galli  Carlo  Sala  Roberto  Colangelo  Maria Teresa  Guizzardi  Stefano 《Scientometrics》2022,127(7):3879-3910
Scientometrics - A literature search on the in vitro testing of anti-inflammatory compounds of natural origin revealed a considerable number of studies adopting a similar template for data...  相似文献   
2.
Journal of Low Temperature Physics - We have investigated disorder phenomena in solid 4He near megting in presence of vacancies by means of Quantum Monte Carlo (MC) simulations using the Shadow...  相似文献   
3.
In human esophageal cancers, no ras gene mutations but a relatively high prevalence of p53 gene mutations have been reported. We found a high prevalence of point mutations in Ha-ras and p53 genes in N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumors in two strains of rats (BD VI and F344). Our analysis showed the point mutation GGA-->GAA (expected from the known mechanisms of action of NMBA) at Ha-ras codon 12 in 22 of 46 (48%) and 22 of 38 (58%) papillomas from BD VI and F344 rats, respectively. There was no significant difference in the prevalence of ras mutations in tumors induced by high doses (5.0 mg/kg) and low doses (2.5 mg/kg) of NMBA. Eleven papillomas from each strain were analyzed for p53 mutations. The prevalent mutations found were G-->A and C-->T transitions. The frequency of p53 mutation was 36% (four of 11) for each strain. No apparent hot-spot codon or exon was found in the p53 gene, and two papillomas contained double mutations in this gene. The high prevalence of G-->A mutations in the rat Ha-ras gene contrasts with that in the human gene, in which no ras mutations have been found in primary tumors, and suggests either that the biology of esophageal carcinogenesis differs in humans and rats or that nitrosamines are not the major etiological risk factor for human esophageal cancers.  相似文献   
4.
The a.c. conductivity of the proteins lysozyme and subtilisin, both in their active and inactive or inhibited forms were determined theoretically. For this, quantum mechanical calculations and a random walk theory were used. The conclusions are that these enzymatic proteins can easily transport electrons which is most probably important in their role as catalysators of biochemical reactions. The electron transport is sensitive to three-dimensional changes of the active sites of these enzymes which have more flexibility than the whole molecule. Therefore, the flexibility of the active sites of enzyme catalysts is not only important for the conformational fitting with the reactants, but also strongly influences the transport in biochemical reactions.  相似文献   
5.
6.
A wandering spleen and splenic cysts are uncommon conditions in children. A combination of both entities has only rarely been reported in the literature. Another case of this complex pathology in 12-year-old girl is presented. She was initially referred for evaluation of a large abdominal mass. Diagnostic studies raised the suspicion of a hematoma in an abnormally located spleen, but the definitive diagnosis was established at laparotomy. Successful surgical management consisted of total cystectomy and splenopexy.  相似文献   
7.
The use of online arithmetic was often proposed for hardware implementations of complex digital-signal processing (DSP) algorithms. However, several important issues in the design process of such algorithms using online arithmetic are rarely discussed in the literature. This paper presents these issues and provides a methodology to analyze the behavior of networks of online arithmetic modules performing serial computation over fixed-point numbers. The methodology is presented, applied in several examples, and finally used to design an efficient field programmable gate arrays implementation of the Levinson-Durbin algorithm in an application of the Yule-Walker power spectrum estimation. The methodology can be applied to other algorithms as well and it simplifies the task of designing and verifying a network of online modules. The experimental results show the advantages of online arithmetic in the design of complex DSP algorithms.  相似文献   
8.
9.
We have developed a monoclonal antibody (BAT) to Daudi B lymphoblastoid cell line membranes. The antibody was selected for its ability to stimulate lymphocyte proliferation. Splenocytes of BALB/c or C57BL mice given i.v. injections of 10 micrograms/mouse of BAT exhibited increased proliferation and cytotoxic activity. A single i.v. administration of BAT monoclonal antibody 2 weeks after B16 melanoma cell inoculation resulted in a striking antitumor effect as manifested by the elimination of lung metastases and prolonged survival of the treated mice. BAT monoclonal antibody was also effective in the regression of tumors in mice bearing 3LL (Lewis lung carcinoma) and MCA-105 (fibrosarcoma). Transfer of 10(7)-10(8) splenocytes from mice that had been given injections of BAT to B16- or 3LL-inoculated recipients led to a reduction of lung metastases. Splenocytes from B16-inoculated mice that were cured by BAT were more effective than those from mice treated with BAT alone against recipients bearing either B16 or 3LL tumors. The antitumor activity of BAT is related to its immunostimulatory properties.  相似文献   
10.
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