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   303篇
  免费   6篇
  国内免费   1篇
电工技术   3篇
化学工业   33篇
金属工艺   14篇
机械仪表   17篇
建筑科学   3篇
能源动力   14篇
轻工业   17篇
水利工程   1篇
石油天然气   14篇
无线电   15篇
一般工业技术   106篇
冶金工业   56篇
原子能技术   2篇
自动化技术   15篇
  2023年   2篇
  2022年   1篇
  2021年   6篇
  2020年   7篇
  2019年   9篇
  2018年   10篇
  2017年   11篇
  2016年   6篇
  2015年   9篇
  2014年   8篇
  2013年   23篇
  2012年   11篇
  2011年   13篇
  2010年   16篇
  2009年   19篇
  2008年   18篇
  2007年   11篇
  2006年   13篇
  2005年   6篇
  2004年   8篇
  2003年   2篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
  1999年   2篇
  1998年   3篇
  1997年   4篇
  1996年   12篇
  1995年   6篇
  1994年   5篇
  1993年   5篇
  1992年   4篇
  1991年   7篇
  1990年   2篇
  1989年   5篇
  1988年   7篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1982年   3篇
  1981年   6篇
  1980年   2篇
  1979年   2篇
  1974年   1篇
  1969年   1篇
排序方式: 共有310条查询结果,搜索用时 31 毫秒
1.
2.
3.
Cajanus trypsin inhibitor (CTI) and Cajanus trypsin-chymotrypsin inhibitor (CTCI) previously purified from cv TAT-10 were further characterised. The modification of the inhibitors revealed the presence of lysine at the trypsin reactive site in both CTI and CTCI. Modification of tyrosine at the reactive site of CTCI did not abolish chymotrypsin inhibition suggesting the presence of leucine or phenylalanine as reported in other chymotrypsin inhibitors. CTCI did not contain tryptophan. Dissociation constants for the inhibitors with bovine trypsin were in the region of 0.69 nmol (CTCI) and 0.029 nmol (CTI). Although the protease inhibitors lost their inhibitory activity on exposure to 2-mercaptoethanol they remained attached to the enzyme. The inhibitors were not very effective against the protease from Helicoverpa armigera which is a serious field pest of Cajanus. Dissociation constants for the inhibitors with the larval enzyme were in the region of 100 nmol.  相似文献   
4.
5.
Fixed-bed column studies were conducted to evaluate the potential of co-immobilized (activated carbon and Bacillus subtilis) (CI) beads for the removal of Cr(VI) from aqueous solution. The impact of various parameters such as initial Cr(VI) concentrations (100, 150, and 200 mg/L), flow rate (3, 9, and 15 mL/min), and bed depth (10, 15, and 20 cm) on Cr(VI) adsorption onto CI beads were investigated. The breakthrough time increased with a decrease in initial Cr(VI) concentration and flow rate, and an increase in bed height. The breakthrough data obtained for Cr(VI) removal was more adequately described by the Thomas model with high correlation coefficients (R 2 = 0.982). The eluent, 0.1 M NaOH, provided high elution efficiencies (~90 %) in all the six cycles. Obtained results pointed out that CI beads could potentially be used for the removal of Cr(VI) from aqueous solution.  相似文献   
6.
The red emitting Ca0.5Gd(WO4)2:Eu3+ was synthesized by a solid-state reaction method. X-ray diffraction patterns were used to characterize crystal structure as well as phase purity. The results suggest that the as synthesized powder phosphor possess scheelite crystal structure with tetragonal symmetry along with the space group of I41/a. SEM studies reveal that the as synthesized sample show polyhedral morphology with particle size of 5.5 µm. Photoluminescence excitation spectrum depicts that a broad band (from 200 to 300 nm) centered at 242 nm is attributed to the ligand to metal charge transfer transition of WO4 2? and three intense with sharp absorption bands (observed at 394, 464 and 535 nm) are designated as f–f electronic transitions of Eu3+. Photoluminescence emission studies indicate that, under 394 nm UV excitation, a hypersensitive red emission was observed at 617 nm due to the transition from upper 5D0 level to the 7F2 lower level of Eu3+ ion. The spectroscopic behaviour of the as synthesized phosphor Ca0.5Gd(WO4)2:Eu3+ was determined using Judd–Ofelt theory. The CIE color coordinates, colour correlated temperature and luminous efficacies of radiation were estimated. The as obtained results indicating that the Ca0.5Gd(WO4)2:Eu3+ red phosphor is most suitable for solid state lighting applications.  相似文献   
7.
In this paper we classify the complexity of several problems based on Abelian permutation groups and linear congruences using logspace counting classes. The problems we consider were defined by McKenzie & Cook (1987).  相似文献   
8.
Drilling trials have been carried out on glass Fibre reinforced plastics (GFRP) with plain high speed steel (HSS), TiN coated HSS and tipped tungsten carbide drills. Most of the defects in drilling of composites are due to thrust force experienced by the workpiece. The parametric influence on cutting force was experimentally evaluated. The experimental results show that the defects toleranced drilling can be attained by proper selection of cutting parameters and tool material. This is substantiated by monitoring flank wear, hole shrinkage and acoustic emission during drilling.  相似文献   
9.
Journal of Mechanical Science and Technology - This paper investigates the tribological characteristics of modified jojoba oil (MJO) as a base stoke for SAE20W40 mineral oil (LO). In addition, a...  相似文献   
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