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   728篇
  免费   27篇
电工技术   14篇
综合类   5篇
化学工业   84篇
金属工艺   18篇
机械仪表   16篇
建筑科学   14篇
矿业工程   8篇
能源动力   26篇
轻工业   59篇
水利工程   1篇
石油天然气   2篇
无线电   107篇
一般工业技术   90篇
冶金工业   213篇
原子能技术   1篇
自动化技术   97篇
  2024年   3篇
  2023年   3篇
  2022年   7篇
  2021年   13篇
  2020年   17篇
  2019年   3篇
  2018年   9篇
  2017年   10篇
  2016年   11篇
  2015年   12篇
  2014年   11篇
  2013年   37篇
  2012年   27篇
  2011年   24篇
  2010年   30篇
  2009年   28篇
  2008年   19篇
  2007年   36篇
  2006年   25篇
  2005年   15篇
  2004年   13篇
  2003年   25篇
  2002年   24篇
  2001年   14篇
  2000年   16篇
  1999年   15篇
  1998年   63篇
  1997年   47篇
  1996年   30篇
  1995年   20篇
  1994年   13篇
  1993年   12篇
  1992年   9篇
  1991年   10篇
  1990年   10篇
  1989年   10篇
  1988年   5篇
  1987年   8篇
  1986年   10篇
  1985年   5篇
  1984年   6篇
  1983年   3篇
  1982年   5篇
  1981年   8篇
  1977年   4篇
  1976年   6篇
  1975年   5篇
  1970年   3篇
  1964年   2篇
  1957年   2篇
排序方式: 共有755条查询结果,搜索用时 15 毫秒
81.
82.
Cell-mediated immunity is a crucial part of recovery from virus infections. Adoptive transfer of T cells into infected animals is restricted by the need for Ag-specific and MHC-restricted T cells. One way to overcome these limitations is to use bifunctional Abs to redirect the T cells against virus-infected cells. We have demonstrated that bifunctional Abs can inhibit virus replication in the presence of activated T cells. To generate a large number of activated T cells in a short time, we tested the ability of the superantigen, staphylococcal enterotoxin B (SEB), to activate T cells. We demonstrate that SEB-activated T cells are effective killers when bridged to Fc receptor-bearing target cells using anti-CD3 Abs. SEB T cells can lyse virus-infected target cells in the presence of HHA6, a bifunctional Ab specific for the V beta 8 TCR product and the H1 hemagglutinin of influenza A/PR/8/34 virus. In addition, bifunctional Ab and SEB T cells can inhibit multicycle virus replication in vitro. In a conventional 4-h chromium release assay, SEB-activated CD8 T cells are efficient killers, whereas CD4 T cells are not. Yet both subpopulations have the ability to inhibit multicycle replication in vitro. Superantigens may represent a potent method for generation of effector cells for use in redirected immunotherapy protocols.  相似文献   
83.
84.
本文根据石宝露天铁矿的实际地质情况及其边坡目前已经产生的一些不良状况,对影响边坡稳定性的诸多因素进行全面的分析,并采用极限平衡法中的Bishop法对该矿的边坡稳定性进行分析计算,通过计算得到的安全系数来判断该边坡是否稳定,并提出一些合理的整改及加固措施,为石宝铁矿的安全生产提供科学依据。  相似文献   
85.
平沟煤矿瓦斯治理中采空区埋管抽放技术的应用   总被引:1,自引:0,他引:1  
详细分析了采煤过程中瓦斯涌出量增大的原因,概述了采空区埋管抽放技术的工作原理。该技术成功地对平沟煤矿0908综采工作面采煤过程中产生的瓦斯进行了有效地治理,保证了采煤工作面安全、稳定、高效的生产。  相似文献   
86.
In many parts of the world, mine production and expansion are increasingly limited by access to water. One solution is to consider a water market that would allow trading of mine site water (worked water) from wetter mines to drier mines. However, there is currently no policy support for such a market and it is likely that without government support via incentives, mines will continue to favour freshwater use because it is relatively inexpensive. Furthermore, mines have a high capacity to pay for the water they use, and freshwater creates few risks for production. The opportunity provided by water savings within a trading scheme could be viewed as a source of money to provide incentives for the transfer of worked water between mines. In this paper, we present a new method to trade water among mines based on a site water balance assessment utilising historical climate data, and apply this method to a demonstration region containing multiple coal mines. On average, 340 ML could be transferred per year to drier mines but there remains 11,440 ML per year of water demand unable to be met by trading. The direct monetary value of the worked water that could be transferred, derived from additional coal mining, would be significant. Irrigation may be an attractive option if available infrastructure can be used to trade the saved fresh water in existing markets, thereby providing indirect monetary value (i.e. external to coal production). Alternative uses of water savings may have considerable additional non-monetary value that directly affects the mining industry’s social license-to-operate and its security of long term water supply.  相似文献   
87.
88.
89.
Pre-screening of cosmetic ingredients is vital for consumer safety. Previous in vivo techniques, such as the Draize test, have proved to be unreliable in predicting ocular irritancy and therefore there is a need for alternate testing methodologies. One such test is the scanning laser in vitro assay system which quantifies irritancy based on the focusing ability of the cultured bovine lens. In combination with confocal microscopy, a more thorough documentation of ocular irritancy can be achieved. This study investigates the response of cultured bovine lenses over time to butyl, methyl and propyl parabens, which are common antimicrobial agents found in cosmetic and ophthalmic products. The focusing ability of the lens was measured with an automated laser scanner over a period of 96 h. At 120 h post-treatment, the lenses were analysed by using a confocal laser scanning microscope to determine the characteristics of nuclei, and the morphology and distribution of mitochondria within the lenses. Irritancy to the three parabens was investigated at both an optical and cellular level. Each of the parabens was tested at 0.002% and 0.2%, where the 0.2% butyl paraben was found to be the most irritating.  相似文献   
90.
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