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   1642696篇
  免费   26965篇
  国内免费   7133篇
电工技术   35097篇
综合类   6527篇
化学工业   278693篇
金属工艺   66484篇
机械仪表   47078篇
建筑科学   48802篇
矿业工程   11790篇
能源动力   50665篇
轻工业   127587篇
水利工程   16755篇
石油天然气   38227篇
武器工业   152篇
无线电   201150篇
一般工业技术   305899篇
冶金工业   231332篇
原子能技术   34560篇
自动化技术   175996篇
  2021年   15817篇
  2020年   12177篇
  2019年   14933篇
  2018年   19290篇
  2017年   18819篇
  2016年   23298篇
  2015年   17885篇
  2014年   29091篇
  2013年   88692篇
  2012年   39283篇
  2011年   54600篇
  2010年   46183篇
  2009年   53724篇
  2008年   49846篇
  2007年   47821篇
  2006年   47448篇
  2005年   43057篇
  2004年   44474篇
  2003年   44133篇
  2002年   42559篇
  2001年   40011篇
  2000年   37966篇
  1999年   38373篇
  1998年   66826篇
  1997年   52338篇
  1996年   43780篇
  1995年   35697篇
  1994年   32702篇
  1993年   32698篇
  1992年   27314篇
  1991年   24561篇
  1990年   24825篇
  1989年   23893篇
  1988年   22417篇
  1987年   20602篇
  1986年   19980篇
  1985年   23249篇
  1984年   22868篇
  1983年   20802篇
  1982年   19679篇
  1981年   19904篇
  1980年   18508篇
  1979年   18830篇
  1978年   18107篇
  1977年   18832篇
  1976年   21339篇
  1975年   16243篇
  1974年   15677篇
  1973年   15831篇
  1972年   13236篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
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   
74.
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   
75.
76.
Programming and Computer Software - Image segmentation using a hierarchical sequence of piecewise constant approximations that minimally differ from the original image in terms of the total squared...  相似文献   
77.
78.

To increase the efficiency of designing systems intended for monitoring surface cracks in aluminum structures during their working life, we have analyzed a two-dimensional symmetric problem on uniaxial extension of an Al-polyimide-Cu layered structure with ideal adhesion between layers and a model crack in the aluminum base. The problem has been first solved for a sample with the crack modeled by a zero-thickness notch using the ANSYS engineering simulation program package. It is shown that this setting of the problem can lead to inadequate results as manifested, in particular, by significantly overstated mechanical stresses in aluminum in the region of crack emergence on the surface. In order to eliminate this difficulty, we propose to use the structure with a model defect in the form of a notch of nonzero thickness in the initial unstressed state of the structure. Recommendations for selecting the thickness of a notch used in the model structure are given.

  相似文献   
79.
80.
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