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   405027篇
  免费   29639篇
  国内免费   18998篇
电工技术   25331篇
技术理论   75篇
综合类   50372篇
化学工业   45357篇
金属工艺   11902篇
机械仪表   18691篇
建筑科学   61423篇
矿业工程   23329篇
能源动力   14344篇
轻工业   21297篇
水利工程   31564篇
石油天然气   19956篇
武器工业   2967篇
无线电   23596篇
一般工业技术   25190篇
冶金工业   23324篇
原子能技术   3986篇
自动化技术   50960篇
  2024年   1161篇
  2023年   3779篇
  2022年   7358篇
  2021年   9095篇
  2020年   9830篇
  2019年   7943篇
  2018年   7514篇
  2017年   9373篇
  2016年   11042篇
  2015年   12101篇
  2014年   24642篇
  2013年   22195篇
  2012年   27729篇
  2011年   29369篇
  2010年   23047篇
  2009年   24074篇
  2008年   22501篇
  2007年   29054篇
  2006年   27130篇
  2005年   23771篇
  2004年   20017篇
  2003年   18051篇
  2002年   14937篇
  2001年   12255篇
  2000年   10261篇
  1999年   8193篇
  1998年   6083篇
  1997年   5161篇
  1996年   4600篇
  1995年   3943篇
  1994年   3331篇
  1993年   2507篇
  1992年   2159篇
  1991年   1623篇
  1990年   1365篇
  1989年   1252篇
  1988年   981篇
  1987年   704篇
  1986年   574篇
  1985年   511篇
  1984年   478篇
  1983年   368篇
  1982年   262篇
  1981年   191篇
  1980年   157篇
  1979年   138篇
  1978年   70篇
  1977年   97篇
  1976年   65篇
  1975年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Buffalo milk Cheddar cheese samples of different ages were analysed for compositional attributes (CA), ripening indices (RI) and Instron Textural Profile (ITP). All samples were compositionally alike, except for pH and salt-in-moisture (SM) contents. RI showed significant variations. CA and RI showed highly significant correlations within themselves and with each other, except for moisture with pH, SM with moisture, MNFS, Fat and FDM and Fat with MNFS. The ITPs of cheeses showed significant variations and had highly significant intercorrelations indicating their interdependence. CA (except moisture and MNFS) and RI showed a highly significant correlationship with ITPs. Moisture content showed a highly significant correlationship with all ITPs, except cohesiveness and springiness, where it was significant. MNFS content showed significant correlations only with hardness and brittleness. Stepwise regression analysis revealed that MI was the most predominant factor influencing cheese texture, followed by pH, SM, FDM and TVFA. Knowing Ca and RI, the textural properties of cheeses can be forecast through mathematical equations. Similarly the age of cheese can also be predicted if RI and/or textural properties are known.  相似文献   
112.
钛容器的特点   总被引:2,自引:1,他引:1  
根据钛材的化学、物理、力学和工艺性能介绍了钛容器在设计、制造、检验和应用方面的特点。  相似文献   
113.
In executing tasks involving intelligent information processing, the human brain performs better than the digital computer. The human brain derives its power from a large number [O(1011)] of neurons which are interconnected by a dense interconnection network [O(105) connections per neuron]. Artificial neural network (ANN) paradigms adopt the structure of the brain to try to emulate the intelligent information processing methods of the brain. ANN techniques are being employed to solve problems in areas such as pattern recognition, and robotic processing. Simulation of ANNs involves implementation of large number of neurons and a massive interconnection network. In this paper, we discuss various simulation models of ANNs and their implementation on distributed memory systems. Our investigations reveal that communication-efficient networks of distributed memory systems perform better than other topologies in implementing ANNs.  相似文献   
114.
What has become known as Community Operational Research has been around in the UK for many years. The election of Jonathan Rosenhead as President of the UK OR Society in 1986–87 was the catalyst for bringing together and expanding activities which had been carried out largely by individuals working in isolation on a voluntary basis. The following five years have seen the establishment of the Community OR Unit at Northern College, the Centre for Community OR at Hull University and the Community OR Network, which supports the activities of volunteer OR workers across the UK. This paper reviews the range and types of work which have been undertaken by various practitioners. An assessment of the success of community OR is made and a number of issues which have arisen are discussed. Finally, given the diverse nature of community OR, its practice and practitioners, there is some discussion about the future of the area.  相似文献   
115.
The hydrolysis of isocyanic acid in the gaseous phase has been investigated at temperatures between 553 and 613 K by mass spectrometry and evaluated to obtain the corresponding kinetic data. The reaction order and reaction constant have been determined. Finally, the influence of water on the catalysed formation of melamine from isocyanic acid under the operating conditions employed has been investigated in order to determine whether there is a need to try the process gas.  相似文献   
116.
对洪水分级的浅见   总被引:1,自引:0,他引:1  
洪水的等级划分应考虑流量、水位、防洪能力及灾害等因素,综合这些因素把洪水分成5个等级。1、2级洪水,洪水流量小,水位低,基本无灾;3级洪水,洪水流量较大或水位较高,有一定灾害;4级洪水,为大洪水或高水位,有较大灾害;5级洪水,为特大洪水或高水位,灾情严重。  相似文献   
117.
Solid-waste management, and in particular the disposal of used packaging, is currently the subject of much topical debate. This is driven by both consumer and legislative pressures. Consumers see used packaging as a highly visible element of municipal solid waste, complaining of excessive packaging and low levels of recycling. Legislators, perhaps in pandering to the views expressed by consumer bodies, have been active within the CEC and individual Member States by introducing (or proposing) legislation or similar regulatory tools and targets to facilitate a greater diversion of used packaging from disposal by landfill to alternative solid-waste management practices, in particular recycling, which are widely accepted to have a lower impact on the environment. In this paper the relative environmental profiles of pursuing alternative solid-waste management practices to disposal by landfill are explored, focusing not just on solid waste per se but also on associated considerations of energy consumption and emissions, which are invariably overlooked as factors contributing to the environmental impact of solid-waste management practices.  相似文献   
118.
Effective management of construction projects depends on good access to and control of data, especially data pertaining to cost and schedule control functions. However, the proper design and development of automated mechanisms have not had the facility to acquire and store quality data in a timely manner. The purpose of this paper, then, is to discuss a prototype, automated data acquisition system that was developed to support an integrated project management system. The data acquisition system is composed of an integrated set of electronic forms used in conjunction with a bar coding data-entry tool.  相似文献   
119.
Editorial.     
With this volume, the 47-year old Canadian Journal of Psychology takes a new name and makes a renewed commitment. In retitling the journal the Canadian Journal of Experimental Psychology, the intention is to reflect more clearly what has always been the major goal of the journal--to publish the best new research in experimental psychology, both Canadian and international, in both French and English. I am honoured to become the tenth editor of the major journal for experimental psychology in Canada. CJP has served the field very well; my primary goal is to ensure that CJEP continues to do so. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
120.
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