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   6343篇
  免费   652篇
  国内免费   288篇
电工技术   360篇
综合类   384篇
化学工业   1074篇
金属工艺   413篇
机械仪表   426篇
建筑科学   415篇
矿业工程   163篇
能源动力   202篇
轻工业   695篇
水利工程   113篇
石油天然气   192篇
武器工业   29篇
无线电   703篇
一般工业技术   803篇
冶金工业   361篇
原子能技术   92篇
自动化技术   858篇
  2024年   38篇
  2023年   129篇
  2022年   275篇
  2021年   326篇
  2020年   229篇
  2019年   163篇
  2018年   208篇
  2017年   221篇
  2016年   223篇
  2015年   278篇
  2014年   358篇
  2013年   455篇
  2012年   442篇
  2011年   464篇
  2010年   351篇
  2009年   393篇
  2008年   358篇
  2007年   309篇
  2006年   318篇
  2005年   249篇
  2004年   159篇
  2003年   182篇
  2002年   177篇
  2001年   154篇
  2000年   111篇
  1999年   103篇
  1998年   106篇
  1997年   61篇
  1996年   68篇
  1995年   83篇
  1994年   53篇
  1993年   45篇
  1992年   35篇
  1991年   27篇
  1990年   21篇
  1989年   14篇
  1988年   17篇
  1987年   11篇
  1986年   6篇
  1985年   5篇
  1984年   4篇
  1983年   6篇
  1981年   8篇
  1980年   6篇
  1977年   6篇
  1976年   6篇
  1975年   3篇
  1974年   3篇
  1969年   4篇
  1951年   2篇
排序方式: 共有7283条查询结果,搜索用时 4 毫秒
1.
余满春  张立红 《辽宁化工》2003,32(8):354-356
介绍了书籍装订热熔胶生产工艺及产品的技术指标,对1000t/a生产装置的投资与产品成本进行了核算。分析结果表明,总投资110万元,年利润达266万元。  相似文献   
2.
This paper gives a first comparison of specific absorption rate (SAR) induced in a child-sized (CS) head and an adult head using a dual-band mobile phone. In the second study, the visible human head is considered and comparison of SAR induced in a CS or child-like (CL) head and an adult head using a dual-band mobile phone is given. All the peaks of average SAR over a mass of 10 and 1 g in the head and the power budget are determined in the two comparisons using the finite-difference time-domain method. The differences between the results for adult and CS or CL heads are given at 900 and 1800 MHz. No important differences are noted for the peak SAR averaged over 10 g (SAR10 g), between the two adult head models, as well as between the two child head models. The peak SAR10 g in the brain of the CS or CL head is slightly more significant than that for the adult one.  相似文献   
3.
Methods are proposed for designing interpolation models for the preliminary determination and subsequent forecasting of general and fractional breakthrough coefficients for dust used with granular filters, as employed in energy-saving and high-performance dust trapping from technological gases and ventilation discharges in refractory production. The models are supplied with nomograms, which makes them widely suitable for experts working in environmental protection at refractory-producing organizations. The main factors are identified that influence the performance. The results are of interest to experts in related areas of industry such as building materials and engineering ceramics and so on. Translated from Novye Ogneupory, No. 4, pp. 64–67, April, 2008.  相似文献   
4.
5.
提出一种金属圆锥弹簧与橡胶圆锥弹簧复合而成的弹簧.分析表明:它可以应用于弹性耦合激励振动筛和座式直线振动筛。  相似文献   
6.
本文介绍了一些国内原有的及近年来发展的用于石材开采的成型爆破方法,简单扼要地阐明了这些方法的原理、装药结构及主要特点,对全面认识及合理选择这些方法有一定帮助。  相似文献   
7.
The rapid advances in molecular biology have begun to shift many of the bottlenecks in genome research from the laboratory to the data analysis facility. The pace at which this has occurred creates a situation in which software development always has to catch up with the flow of data. Since such large-scale processes were not anticipated, the analysis infrastructure has not been fully established. Furthermore, most systems that have been built were designed by the biologists who collected the data. More recently, computer scientists, mathematicians, and engineers have taken an interest in this problem. This has had a positive effect, since it has created a tight synergy between the informatics and the biology. Several principles affected the design of the system developed at TIGR. Each of the sample preparation, sequencing, and analysis steps had to be managed, scheduled, and tracked. This information had to be made readily available to those who needed it for carrying out their tasks. Different skill levels of the users had to be taken into account. The degree of human intervention at each step had to be evaluated and built into the design. A mixed processing environment of Macintosh and Unix platforms had to be integrated. Most importantly, the system had to save time, reduce error, and ensure uniformity of the analysis and quality of the results. In the authors' experience, the tools they have built work well because of their early decisions as to which systems to use for development. The authors settled on a robust relational database management system (Sybase) and a portable development environment (C, C++)  相似文献   
8.
A structured genetic algorithm (SGA) approach is developed for robust controller design based on the concept of an H loop-shaping technique and the method of inequalities. Such an SGA is capable of simultaneously searching the orders and coefficients of the precompensator and postcompensator for the weighted plant. It is, therefore, not necessary to predefine the order of compensators as in usual practice. A multiple objective ranking approach is also incorporated so that the design criteria of extreme plants can be easily achieved. The effectiveness of such a technique is illustrated by a high-purity distillation column design example  相似文献   
9.
This paper introduces genetic algorithms (GA) as a complete entity, in which knowledge of this emerging technology can be integrated together to form the framework of a design tool for industrial engineers. An attempt has also been made to explain “why” and “when” GA should be used as an optimization tool  相似文献   
10.
根据转炉炼钢的物理化学反应机理,从质量平衡和能量平衡的计算出发,通过小参数变动,导出了增量式静态模型中矿石方程和供氧方程的系数。所得结论与新日铁资料基本相符。同时,还进行了炉料和产物的计算,分析了改变废钢比对生产的影响。  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