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   584945篇
  免费   7628篇
  国内免费   1325篇
电工技术   10936篇
综合类   1022篇
化学工业   93701篇
金属工艺   23799篇
机械仪表   19141篇
建筑科学   13376篇
矿业工程   4504篇
能源动力   14986篇
轻工业   47500篇
水利工程   7161篇
石油天然气   15294篇
武器工业   67篇
无线电   62355篇
一般工业技术   118676篇
冶金工业   98141篇
原子能技术   14792篇
自动化技术   48447篇
  2021年   6012篇
  2020年   4314篇
  2019年   5629篇
  2018年   9614篇
  2017年   9798篇
  2016年   10273篇
  2015年   6417篇
  2014年   10805篇
  2013年   27085篇
  2012年   16553篇
  2011年   22191篇
  2010年   17747篇
  2009年   19589篇
  2008年   19876篇
  2007年   19618篇
  2006年   16948篇
  2005年   15254篇
  2004年   14609篇
  2003年   14501篇
  2002年   14324篇
  2001年   13769篇
  2000年   12837篇
  1999年   12423篇
  1998年   28528篇
  1997年   20613篇
  1996年   16068篇
  1995年   12305篇
  1994年   11100篇
  1993年   10858篇
  1992年   8473篇
  1991年   8197篇
  1990年   8096篇
  1989年   7856篇
  1988年   7575篇
  1987年   6832篇
  1986年   6610篇
  1985年   7502篇
  1984年   6762篇
  1983年   6499篇
  1982年   5840篇
  1981年   5967篇
  1980年   5697篇
  1979年   5781篇
  1978年   5700篇
  1977年   6255篇
  1976年   7837篇
  1975年   5148篇
  1974年   4923篇
  1973年   5013篇
  1972年   4299篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
This paper presents part of the work ComEd and Quanta Technology have performed to quantify the locational and temporal value of DER to avoid distribution grid upgrade investments. It focuses on the formulation of a robust and efficient algorithm for DER optimal dispatch on a distribution feeder to mitigate the violation of current and voltage limits using the allocated cost of capacity and locational marginal value of real and reactive DER injection/withdrawal.  相似文献   
2.
3.
Alcohol-free beer with isotonic properties is getting more popular and its production can be carried out by different production strategies; however, interrupted fermentation is still a challenge. Therefore, the objective of this study was to develop a low-alcohol isotonic beer (<0.5% v/v) by interrupted fermentation. Moreover, the major objective is to compare the developed product to commercial beverages (sports drinks, ‘Pilsen' regular beer, alcohol-free beers and low-alcohol isotonic beer). The beverages were evaluated based on pH, alcohol content (% v/v), total titratable acidity (mEq L−1), osmolality (mOsmol kg−1), bitterness International Bitterness Units, colour European Brewery Convention, total phenolic compounds (mg L−1 gallic acid), reducing and total sugars (%) and Na and K contents (mg L−1). The developed low-alcohol isotonic beer presented characteristics similar to sports drinks, with the advantage of being richer in phenolic compounds and suitable osmolality. Despite salts were added in its formulation, the grades attributed to all beers employed in the sensory evaluation, as well as the purchase intention did not present significant differences.  相似文献   
4.
In this study, amaranth flour was used as an ingredient to prepare gluten-free cookies. The production process and attributes of amaranth cookies were characterised, and the potential use of amaranth flour as a functional ingredient was analysed. Cookies exhibited a non-uniform reddish brown colour and a cookie factor ratio of 4.5 ± 0.6. Storage studies indicated that after 3 weeks at room temperature cookies presented slight variations in the texture. Simulated gastrointestinal digestion of this product was able to release peptides capable of exerting potential antithrombotic and antihypertensive activities, IC50 values of 0.22 ± 0.04 and 0.23 ± 0.03 mg mL−1 protein, respectively. This work demonstrates for the first time that food made with amaranth flour exerts potential antithrombotic and antihypertensive activity. In conclusion, these amaranth cookies could be an alternative way of incorporating potentially health beneficial products for people who choose a conscious diet, including coeliac or vegan consumers.  相似文献   
5.
6.
7.
8.
9.
10.

Stability constants and formation enthalpies of supramolecular complexes of crown ethers and their cyclic and acyclic analogues are determined on the basis of experimental data obtained by different physicochemical methods in the terms of a general approach developed and implemented in the ChemEqui software package. The established regularities of variation of stability of complexes are discussed as dependent on the ligand structure, nature of the cation, solvent, and anion. The applicability of the suggested method of determining complexation selectivity is shown for multicomponent equilibria in solutions.

  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