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   4690篇
  免费   106篇
  国内免费   4篇
电工技术   38篇
综合类   1篇
化学工业   1023篇
金属工艺   56篇
机械仪表   81篇
建筑科学   242篇
矿业工程   21篇
能源动力   75篇
轻工业   438篇
水利工程   35篇
石油天然气   22篇
无线电   222篇
一般工业技术   858篇
冶金工业   1093篇
原子能技术   33篇
自动化技术   562篇
  2022年   31篇
  2021年   43篇
  2020年   46篇
  2019年   46篇
  2018年   58篇
  2017年   42篇
  2016年   72篇
  2015年   67篇
  2014年   127篇
  2013年   274篇
  2012年   188篇
  2011年   250篇
  2010年   169篇
  2009年   183篇
  2008年   236篇
  2007年   200篇
  2006年   212篇
  2005年   189篇
  2004年   147篇
  2003年   138篇
  2002年   127篇
  2001年   84篇
  2000年   101篇
  1999年   74篇
  1998年   78篇
  1997年   96篇
  1996年   88篇
  1995年   70篇
  1994年   77篇
  1993年   85篇
  1992年   81篇
  1991年   53篇
  1990年   78篇
  1989年   73篇
  1988年   55篇
  1987年   76篇
  1986年   70篇
  1985年   78篇
  1984年   76篇
  1983年   56篇
  1982年   58篇
  1981年   61篇
  1980年   35篇
  1979年   51篇
  1978年   48篇
  1977年   37篇
  1976年   33篇
  1975年   34篇
  1974年   30篇
  1972年   27篇
排序方式: 共有4800条查询结果,搜索用时 15 毫秒
21.
This study investigated whether sex discrimination existed in recruiters' evaluations of applicants in real employment interviews and, if so, whether other variables could explain it. The variables examined were the perceived similarity of the applicant to the recruiter, the interpersonal attraction felt by the recruiter toward the applicant, and the applicant's objectively measured and subjectively measured qualifications. Applicant sex did not directly or indirectly affect recruiters' evaluations of applicants in campus interviews, providing no evidence of sex discrimination. Instead, subjective qualifications had a significant effect on evaluations and also mediated the effects of perceived similarity, interpersonal attraction, and objective qualifications on evaluations. Recruiters saw stronger subjective qualifications in applicants with high scholastic performance whom they viewed as similar to themselves and whom they liked. Perceptions of these qualifications, in turn, were the primary determinant of evaluations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
22.
The last decade has seen the development of a number of approaches for estimating those variables which are difficult to measure on-line in industrial process situations. Whilst a range of techniques is available, a common element is the use of process knowledge in the form of a system model. In the case of bioprocess systems, although a large range of models has been presented in the literature, their use in estimation schemes on an industrial scale has been limited. A number of reasons can be identified for their low level of utilisation. Of particular significance is the uncertainty which exists in quantifying system performance and the process-model mismatch which inevitably results. The level of ‘pre-defined model’ uncertainty, together with the knowledge gained during the course of the fermentation, serves to dictate estimator structure. The paper considers a range of estimation strategies and contrasts, through industrial applications, their performance characteristics and utility.  相似文献   
23.
24.
As demonstrated by Aaronson and his colleagues over five decades or so, the structure, energy, and dynamic response of interphase boundaries in metallic systems are strongly correlated. It has also become clear that very few, if any, solid/solid transformation interfaces can be considered truly “incoherent.” Most treatments of the geometry of irrational interfaces (facet planes) have focused on the density of coincidence sites or near-coincidence sites (NCS); this naturally involves consideration of the matching of densely packed atomic planes lying parallel to the facet. Edge-to-edge plane matching represents an alternative and, perhaps, more general approach to the geometry of transformation interfaces. For diffusional transformations, growth ledges are required to displace and reproduce the structure of the facet plane; their geometrical properties are distinct from those of the interfacial facets. The role of local thermodynamic driving force in determining the migration mode is assessed. Several recent observations of the transient faceting of irrational interfaces, for which the density of NCS is relatively low, have stimulated considerations of the significance of the invariant-line condition and of edge-to-edge plane matching as criteria for local minima in interfacial free energy. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.  相似文献   
25.
26.
The differential effectiveness of group psychotherapy was estimated in a meta-analysis of 111 experimental and quasi-experimental studies published over the past 20 years. A number of client, therapist, group, and methodological variables were examined in an attempt to determine specific as well as generic effectiveness. Three different effect sizes were computed: active versus wait list, active versus alternative treatment, and pre- to posttreatment improvement rates. The active versus wait list overall effect size (0.58) indicated that the average recipient of group treatment is better off than 72% of untreated controls. Improvement was related to group composition, setting, and diagnosis. Findings are discussed within the context of what the authors have learned about group treatment, meta-analytic studies of the extant group literature, and what remains for future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
27.
MRI techniques were developed and employed for non-destructive and noninvasive study of seedcoat cracking in low moisture soybean kernels during heated air drying. Proton density image and transient moisture distribution profile of a single soybean kernel can be obtained using MRI. These MRI techniques proved to be particularly useful for the continuous observation of initiation and propagation of seedcoat cracking during the entire period of drying process without interruption.

The proton density images of soybean kernels showed that seedcoat cracking was initiated perpendicular to the long axis of the kernel near the hilum. The transient moisture distribution profiles in soybean kernels during drying indicate that moisture gradient developed during drying was higher in the seedcoat than in the cotyledon. Drying temperature and initial average moisture content were positively correlated with the soyhean seedcoat crackig. The location of the  相似文献   
28.
Comments on B. Vandenberg's (see record 1992-12211-001) article on epistemology and an existential consideration of development, taking exception with both his definition of existentialism and his characterization of Piaget's work. Existentialism, it is argued, is not an alternative to epistemology, but a particular style of responding to philosophic questions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
29.
30.
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