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   656篇
  免费   45篇
  国内免费   13篇
电工技术   3篇
综合类   30篇
化学工业   63篇
金属工艺   22篇
机械仪表   19篇
建筑科学   26篇
矿业工程   16篇
能源动力   13篇
轻工业   273篇
水利工程   1篇
石油天然气   11篇
武器工业   3篇
无线电   11篇
一般工业技术   185篇
冶金工业   15篇
原子能技术   9篇
自动化技术   14篇
  2024年   2篇
  2023年   19篇
  2022年   13篇
  2021年   31篇
  2020年   21篇
  2019年   21篇
  2018年   21篇
  2017年   21篇
  2016年   15篇
  2015年   17篇
  2014年   31篇
  2013年   47篇
  2012年   35篇
  2011年   42篇
  2010年   25篇
  2009年   29篇
  2008年   46篇
  2007年   39篇
  2006年   32篇
  2005年   26篇
  2004年   24篇
  2003年   26篇
  2002年   25篇
  2001年   15篇
  2000年   16篇
  1999年   12篇
  1998年   11篇
  1997年   11篇
  1996年   7篇
  1995年   6篇
  1993年   3篇
  1992年   4篇
  1991年   4篇
  1990年   5篇
  1989年   2篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1980年   2篇
  1978年   1篇
  1951年   1篇
排序方式: 共有714条查询结果,搜索用时 15 毫秒
1.
2.
稠油微生物开采技术现状及进展   总被引:2,自引:0,他引:2  
邓勇  易绍金 《油田化学》2006,23(3):289-292
综述了用微生物方法开采稠油的技术现状与进展,论题如下。①概述。②基本方法:异源微生物采油,包括微生物吞吐和微生物驱;本源微生物采油压大港孔店油田的实例。③主要机理,包括产表面活性剂,降解稠油中重质组分及其他。④技术研究,包括机理性、可行性及经济效益研究,列举了国内外6个实例。⑤现场应用,包括国外1个、国内6个实例。⑥该技术的优势及问题。参22。  相似文献   
3.
P. Cappa 《Strain》1989,25(4):139-142
The effects of the uncertainties associated ith the apparent strain and gauge factor data, given by the manufacturer, in the evaluation of principal strains are examined. Principal strains are obtained by a reduction of the strains measured ith electrical resistance strain gauge rectangular or delta rosettes. The theoretical analysis points out the relevance of the effects caused.  相似文献   
4.
The proposed models for irreversible finite deformation of initially anisotropic solids are based on the hypothesis of the parameters of state, for which the authors have chosen a universal parameter (temperature) and a strain component, which is analogous to volume strains in an isotropic body and represents thermal strains of an unconstrained (stress-free) anisotropic solid. The application of this hypothesis allows the strain tensor to be resolved into a reversible and irreversible components. For irreversible processes of finite deformation of hardenable materials, the authors have proposed a deformation-type model, which makes it possible to describe a change in the type of anisotropy of initially anisotropic materials in the course of deformation. For the flow-theory-type model, the limiting state function, as given in the space of irreversible strains, allows for the experimentally observed plastic flow of anisotropic crystals under the action of hydrostatic pressure only.  相似文献   
5.
微生物法处理含硫工业废气   总被引:11,自引:0,他引:11  
指出了含硫工业废气传统处理方法的缺陷 ,介绍了微生物处理方法的优势所在 ;对微生物菌种的共同特征以及无机硫和有机硫脱除时菌种的选择依据进行了讨论 ,并对微生物法脱硫的机理进行了分析 ;评述了国内外生物滤池法、生物滴滤池法和生物吸收法等生物膜法脱硫的工艺及其工业化应用。指出了微生物法脱硫技术有待深入研究的问题、发展趋势和应用前景。  相似文献   
6.
Experiments were conducted to (1) determine whether the electroantennogram (EAG) can detect differences among the responses of antennae from males derived from the three strains ofOstrinia nubilalis (Hübner), and (2) characterize the EAG responses of each strain to isomeric forms of the natural pheromone, (E)- and (Z)-11-tetradecen-1-ol acetate (TDA), and analogs possessing differences in the terminal alkyl group, cyclopropyl (CPA), ortert-butyl (TBA).EAG responses differed among the strains in two ways: (1) Antennae fromZZ males always produced an EAG to (Z)-TDA with an extended duration of response. This signature EAG response was found to be unique to the antennal response ofZZ males to (Z)-TDA, thus providing a relatively easy method of distinguishing liveZZ males fromEE orZE males. Correlated with this longer EAG response was a longer disadaptation time, i.e., the EAG response ofZZ antennae disadapted more slowly (ca. 10 min) than the response ofEE antennae. (2) Strain differences in the relative EAG amplitudes to isomers and analogs were observed at the stimulus amounts eliciting the peak EAG amplitude as follows: TDA CPA > TBA forZZ males and both isomers; TDA > CPA TBA and CPA TDA > TBA forEE males and theE andZ isomers, respectively; CPA > TBA TDA forZE males and both isomers. Dose—response relationships were seen for all compounds if amplitude (peak height) of the EAG was used as a measure of response. However, if width of the EAG at half the peak height (peak width) was used, then only theZZ antennal response to (Z)-TDA resulted in a meaningful dose-response relationship. For all strains, the EAG amplitudes elicited by theZ isomers of any of the tested compounds were greater than those elicited by the correspondingE isomers. Therefore, correlations between the relative EAG and upwind flight responses were observed in theZZ (r = 0.86) andZE (r = 0.80) strains but were not correlated in theEE strain (r = 0.18). Temporal studies showed that adaptation, not postexcision deterioration, was responsible for the observed decreases in the EAG amplitude after repetitive stimulation or after stimulation with amounts in a descending order. Disa-daptation required at least 20 min for a moderate dose (10 g for 1 sec). Developmental studies showed that antennae from 2-day-old adults had the greatest EAG response.  相似文献   
7.
从土样中分离出34株脂肪酶产生菌,在维多利亚蓝培养基上初筛出透明圈与菌落直径比值较大的6株菌,复筛出产脂肪酶活性较高的菌株FM-1,其所产脂肪酶主要为胞内酶,产脂肪酶活力为132 U/g cell。通过反复的驯化培养方式将菌株FM-1驯化成耐甲醇的优良菌株。在甲醇质量浓度为11 mg/L的培养基中驯化后的脂肪酶相对活力为35%,而出发菌株在此环境中不能生长。  相似文献   
8.
The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with the use of finite element method. The influences of the borehole diameter(d), the initial stresses and the ratio of the initial principle stresses on the variations of the remained stress and the released stress in function of the relief depth(h) were discussed. The relation between the non-dimensional ratio of the released principle strains and that of the initial principle stresses, and the effect of the elastic modulus and the Poisson ratio of the rock mass on the stress relief curves were studied. The results show that the stress relief behavior formulated with the non-dimensional ratio of the released stress and the ratio of h/d is only sensitive to the ratio of the initial principle stresses and the Poisson ratio. The stresses are completely released when h equals 1.6d, and the tensile stresses take place on the bore core surface in the relief measurement process. Finally, a non-complete relief method of annular hole-drilling for measuring surface stress in surrounding rocks is proposed and the procedure is presented.  相似文献   
9.
DEPENDENCEOFPREDICTIONMODELOFFORMINGLIMITSTRAINSONFORMINGMETHODANDMECHANICALPROPERTIESOFSHEETMETALS①ZhouWeixianDepartmentofAe...  相似文献   
10.
The presence of a concentration gradient across a thin liquid film leads to the phenomenon of isothermal liquid film migration (LFM). In most cases, the concentration gradient is due to coherency stresses, and the migration of the liquid film results in the relaxation of these stresses. It is also possible to envisage cases in which LFM occurs as a result of chemical solubility differences between stable and metastable phases. Both situations are examined in this contribution with special emphasis on the effect of adding a second solute element to the liquid phase. The kinetics of LFM is examined as a function of the initial liquid concentration and the ratio of the solute diffusion coefficients in a model coherency-driven ternary system. The growth of the Γ2 inside δ particles in the Zn-Fe-Al system is presented as a possible example of chemically driven LFM. This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University.  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