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   135篇
  免费   1篇
  国内免费   1篇
电工技术   1篇
综合类   2篇
化学工业   14篇
金属工艺   2篇
机械仪表   2篇
建筑科学   2篇
轻工业   3篇
水利工程   1篇
石油天然气   7篇
无线电   11篇
一般工业技术   12篇
冶金工业   57篇
原子能技术   1篇
自动化技术   22篇
  2022年   2篇
  2021年   2篇
  2018年   1篇
  2017年   1篇
  2014年   2篇
  2013年   4篇
  2012年   6篇
  2011年   3篇
  2010年   3篇
  2009年   1篇
  2008年   3篇
  2007年   2篇
  2006年   4篇
  2005年   3篇
  2004年   8篇
  2003年   3篇
  2002年   4篇
  2001年   1篇
  2000年   6篇
  1999年   6篇
  1998年   9篇
  1997年   12篇
  1996年   6篇
  1995年   6篇
  1994年   3篇
  1993年   8篇
  1991年   2篇
  1990年   4篇
  1989年   5篇
  1988年   2篇
  1987年   4篇
  1985年   1篇
  1984年   2篇
  1981年   1篇
  1980年   2篇
  1977年   1篇
  1976年   2篇
  1969年   1篇
  1966年   1篇
排序方式: 共有137条查询结果,搜索用时 31 毫秒
1.
Press  L. 《Computer》1993,26(12):62-67
It is shown that software export is an attainable goal for developing nations, especially when government policies are favorable, and that the industrialized nations dominating the worldwide market can expect some serious competition. Examples of the efforts of developing nations to export software to North America and Europe are cited  相似文献   
2.
This paper deals with the design of passive coplanar devices in the W-frequency band. As long as coplanar transmission lines are correctly dimensioned, analytical models based on quasi-TEM approximation can be used. Such models are associated with a correct definition of the reference planes at the junctions and employed for junction discontinuities, T- and cross-junctions. In order to validate these assertions, simulated and experimental data on classical quarter-wavelength shunt-stub filters are first presented. Then the design of traditional coupled-line filters is examined. The problems in terms of insertion loss associated with these kinds of narrow-band applications are discussed here. Minimization of insertion losses requires increasing the width of the strips. Consequently, the design becomes complex and modeling using transmission-line models less accurate. Nevertheless, as an optimization procedure is needed to tune the filter theoretically, such a very fast design method is necessary. Simulated and experimental results in the range 500 MHz to 110 GHz are compared throughout the paper.  相似文献   
3.
Examples of formation of troublesome deposits containing ellagic acid in the wood pulping process are mentioned. The deposit from one such process in the U.K. has been examined in detail. This paper is mainly devoted to the determination of some physico-chemical properties of ellagic acid, which are relevant to the study of minimising the formation of the deposit in the wood digester. A specially built apparatus was used for the determination of these properties at 170° (the normal digestion temperature). The ultra-violet and visible absorption spectra measured at different pH values and temperatures were used to determine a dissociation constant of the acid at 20° which was found to be 11·0. The solubility of the acid was determined at 20°, 90° and 170°. From the changes in absorbance at 250 nm the decomposition was found to consist of two consecutive firstorder reactions, the rate constant of the first reaction being inversely proportional to a fractional power of hydrogen ion concentration. The activation energy was estimated to be 5·5 kcal and was independent of pH value.  相似文献   
4.
耐候钢表面锈层稳定化处理用新型涂层研究   总被引:4,自引:0,他引:4  
刘丽宏  李明  李晓刚  卢燕平  齐慧滨 《金属学报》2004,40(11):1195-1199
针对耐候钢裸露使用时出现的锈层稳定化时间过长及早期锈液流挂和飞散的问题,提出了Zn—Ca系磷化 丙烯酸树脂—SiO2复合膜新型耐候钢表面锈层稳定化处理技术.采用干湿周浸实验研究了该复合膜耐候钢试样的腐蚀行为和耐大气腐蚀性能.得出了能有效避免锈液流挂、促进耐候钢表面锈层稳定化的最佳复合膜处理工艺,即Zn—Ca磷化 B—13Si(120℃)复合膜处理.并从理论上探讨了该复合膜提高耐候钢抗大气腐蚀性能、促进表面锈层稳定化的作用机理和模型。  相似文献   
5.
Microsystem Technologies - This study presents the results on the feasibility of a resonant planar chemical capacitive sensor in the microwave frequency range suitable for gas detection and...  相似文献   
6.
In this work we characterize the session-level behavior of users on an Indian mobile phone comparison shopping website. We also correlate the popularity of handset on various news sources to its popularity on the shopping website. There are three aspects to our study: data analysis, correlation between news sources of product information and popularity of a handset, and behavior prediction. We have used KL divergence to show that a time-homogeneous Markov chain is observed when the number of clicks varies from 5 to 30. Our results depict that Markov chain model does not hold in entirety for comparison shopping setting but tells us how far the Markov chain model holds for this setting. Our analysis corroborates intuition that increasing price leads to decrease in popularity. After the strong correlation between various variables and user behavior was found, we predict the users macro (the overall sales of handset) and micro behavior (whether a user will convert or exit the site) using Markov logic networks. Our predictive model validates the intuition that past browsing behavior is an important predictor for future behavior. Methodology of combining data analysis with machine learning is, in our opinion, a new approach to the empirical study of such data sets.  相似文献   
7.
The understanding of violent criminal behavior is hindered by definitional problems in both the legal and research communities. Different definitions of violent criminal behavior and different classifications of the severity of violence are fundamental problems that need to be resolved in order to develop better conceptual models of the precursors to criminal violence that can inform management and treatment of violent young offenders. This study evaluated 6 classifications of violent juvenile offenses derived from the legal system and published research. The authors compare frequencies from different classifications and examine the influence of classifications on observed associations with expected predictor variables. Differences in frequencies and perceived associations between classifications highlight the need to adopt a consistent method of coding violent offenses for research purposes in order to obtain valid results that are capable of informing policy, the judiciary, and the development of effective interventions. The final classification system offers a method of systematic coding based on the type, frequency, and outcome of the violent behavior that distinguishes between levels of violence severity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
8.
9.
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