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   278650篇
  免费   5329篇
  国内免费   2131篇
电工技术   5844篇
技术理论   5篇
综合类   1706篇
化学工业   45445篇
金属工艺   11477篇
机械仪表   8388篇
建筑科学   7373篇
矿业工程   1839篇
能源动力   6096篇
轻工业   27506篇
水利工程   3111篇
石油天然气   6164篇
武器工业   270篇
无线电   29843篇
一般工业技术   51546篇
冶金工业   50188篇
原子能技术   5748篇
自动化技术   23561篇
  2021年   2915篇
  2020年   1917篇
  2019年   2428篇
  2018年   3733篇
  2017年   3677篇
  2016年   4049篇
  2015年   3127篇
  2014年   5069篇
  2013年   12255篇
  2012年   8386篇
  2011年   11040篇
  2010年   8799篇
  2009年   9397篇
  2008年   10169篇
  2007年   10307篇
  2006年   9039篇
  2005年   7905篇
  2004年   7268篇
  2003年   7026篇
  2002年   7324篇
  2001年   7257篇
  2000年   6428篇
  1999年   6323篇
  1998年   13905篇
  1997年   10198篇
  1996年   7783篇
  1995年   5880篇
  1994年   5346篇
  1993年   5237篇
  1992年   4103篇
  1991年   3870篇
  1990年   3942篇
  1989年   3886篇
  1988年   3639篇
  1987年   3116篇
  1986年   3144篇
  1985年   3540篇
  1984年   3392篇
  1983年   3151篇
  1982年   2769篇
  1981年   2987篇
  1980年   2729篇
  1979年   2893篇
  1978年   2776篇
  1977年   2924篇
  1976年   3856篇
  1975年   2502篇
  1974年   2318篇
  1973年   2366篇
  1972年   2010篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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   
2.
Qin  Yi  Tao  Xianping  Huang  Yu    Jian 《World Wide Web》2019,22(1):1-37
World Wide Web - Rule mechanism has been widely used in many areas, such as databases, artificial intelligent and pervasive computing. In a rule mechanism, rule activation decides which rules are...  相似文献   
3.
4.
5.
6.
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications.  相似文献   
7.
The viability and β‐galactosidase activity of four Lactobacillus strains in milk drink containing gums during 28 days of refrigerated storage at 4 °C were assessed. The population of Lactobacillus rhamnosus GGB101 and Lactobacillus rhamnosus GGB103 were maintained, whereas the population of Lactobacillus reuteri DSM20016 and Lactobacillus reuteri SD2112 significantly decreased. The recommended level of 6 log CFU g?1 was exceeded for all tested trains throughout storage. The highest viable number of Lactobacillus rhamnosus GGB103 (8.76 ± 0.03 log CFU mL?1) was obtained in the product containing carrageenan–maltodextrin. The addition of guar–locust bean–carrageenan led to 20‐fold increase in the level of β‐galactosidase activity for L. rhamnosus GGB101 (1208 ± 2.12 Miller units mL?1) compared to the control (61 ± 2.83 Miller units mL?1). Our results suggested that gums could be added to milk to improve viability and enhance β‐galactosidase activity of Lactobacillus.  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