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   622300篇
  免费   8537篇
  国内免费   1882篇
电工技术   11318篇
综合类   1166篇
化学工业   93704篇
金属工艺   23930篇
机械仪表   19577篇
建筑科学   13695篇
矿业工程   3625篇
能源动力   15929篇
轻工业   49945篇
水利工程   6585篇
石油天然气   11497篇
武器工业   48篇
无线电   69062篇
一般工业技术   118956篇
冶金工业   126861篇
原子能技术   13438篇
自动化技术   53383篇
  2021年   5362篇
  2020年   3971篇
  2019年   5177篇
  2018年   9167篇
  2017年   9357篇
  2016年   10309篇
  2015年   6616篇
  2014年   10227篇
  2013年   28235篇
  2012年   17604篇
  2011年   23528篇
  2010年   17609篇
  2009年   19729篇
  2008年   20232篇
  2007年   20093篇
  2006年   18043篇
  2005年   18580篇
  2004年   17148篇
  2003年   16475篇
  2002年   14958篇
  2001年   14605篇
  2000年   13427篇
  1999年   14027篇
  1998年   38170篇
  1997年   26214篇
  1996年   20000篇
  1995年   14798篇
  1994年   12839篇
  1993年   12847篇
  1992年   9138篇
  1991年   8554篇
  1990年   8702篇
  1989年   8248篇
  1988年   7921篇
  1987年   6913篇
  1986年   6819篇
  1985年   7731篇
  1984年   7105篇
  1983年   6434篇
  1982年   5999篇
  1981年   6201篇
  1980年   5845篇
  1979年   5559篇
  1978年   5612篇
  1977年   6741篇
  1976年   9175篇
  1975年   4877篇
  1974年   4543篇
  1973年   4700篇
  1972年   3953篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Kamar  M. S.  Shalan  A. S.  Youssef  W. M.  Hussein  A. E. M.  Khawassek  Y. M.  Taha  M. H. 《Radiochemistry》2022,64(2):244-256
Radiochemistry - Ferrugination, sericitization, desulfitization, chloritization, and kaolinitization of hydrothermal origin are the main wall rock alterations occurring within the NNW shear zones...  相似文献   
42.

Modern metrics for evaluating agreement coefficients between the experimental results and expert opinion are compared, and the possibility of using these metrics in experimental research in automatic text processing by machine learning methods is assessed. The choice of Cohen’s kappa coefficient as a measure of expert opinion agreement in the NLP and Text Mining problems is justified. An example of using Cohen’s kappa coefficient for evaluating the level of agreement between the opinion of an expert and the results of ML classification and the measure of agreement of expert opinions in the alignment of sentences of the Kazakh-Russian parallel corpus is given. Based on this analysis, it is proved that Cohen’s kappa coefficient is one of the best statistical methods for determining the level of agreement in experimental studies due to its ease of use, computing simplicity, and high accuracy of the results.

  相似文献   
43.
Wireless Personal Communications - Multiple inputs multiple outputs (MIMO) is a reliable technique which can manage the increased wireless data traffic in the future generation of wireless...  相似文献   
44.
Russian Engineering Research - The stability of robot-mower motion in a specific direction is considered. The direction is regulated by means of an angular sensor and a programmable controller...  相似文献   
45.
This review examines the application, limitations, and potential alternatives to the Hagberg–Perten falling number (FN) method used in the global wheat industry for detecting the risk of poor end-product quality mainly due to starch degradation by the enzyme α-amylase. By viscometry, the FN test indirectly detects the presence of α-amylase, the primary enzyme that digests starch. Elevated α-amylase results in low FN and damages wheat product quality resulting in cakes that fall, and sticky bread and noodles. Low FN can occur from preharvest sprouting (PHS) and late maturity α-amylase (LMA). Moist or rainy conditions before harvest cause PHS on the mother plant. Continuously cool or fluctuating temperatures during the grain filling stage cause LMA. Due to the expression of additional hydrolytic enzymes, PHS has a stronger negative impact than LMA. Wheat grain with low FN/high α-amylase results in serious losses for farmers, traders, millers, and bakers worldwide. Although blending of low FN grain with sound wheat may be used as a means of moving affected grain through the marketplace, care must be taken to avoid grain lots from falling below contract-specified FN. A large amount of sound wheat can be ruined if mixed with a small amount of sprouted wheat. The FN method is widely employed to detect α-amylase after harvest. However, it has several limitations, including sampling variability, high cost, labor intensiveness, the destructive nature of the test, and an inability to differentiate between LMA and PHS. Faster, cheaper, and more accurate alternatives could improve breeding for resistance to PHS and LMA and could preserve the value of wheat grain by avoiding inadvertent mixing of high- and low-FN grain by enabling testing at more stages of the value stream including at harvest, delivery, transport, storage, and milling. Alternatives to the FN method explored here include the Rapid Visco Analyzer, enzyme assays, immunoassays, near-infrared spectroscopy, and hyperspectral imaging.  相似文献   
46.
Multimedia Tools and Applications - Discovering the relevant web services for specific applications in the dynamically changing business world becomes very critical. Researchers have used many...  相似文献   
47.
Journal of Materials Science - For transformers and inductors to meet the world’s growing demand for electrical power, more efficient soft magnetic materials with high saturation magnetic...  相似文献   
48.
Mobile Networks and Applications - 5G/6G communication are first generation high speed wireless communication network which integrates the aerial data, terrestrial data and maritime data via...  相似文献   
49.
Theoretical Foundations of Chemical Engineering - The effect of the electrolyte composition, mass-transfer conditions, pore diameter, interpore distance, and electric parameters on the formation of...  相似文献   
50.
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