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   1905篇
  免费   56篇
  国内免费   5篇
电工技术   33篇
综合类   2篇
化学工业   285篇
金属工艺   26篇
机械仪表   64篇
建筑科学   96篇
矿业工程   6篇
能源动力   78篇
轻工业   121篇
水利工程   29篇
石油天然气   13篇
无线电   153篇
一般工业技术   324篇
冶金工业   428篇
原子能技术   4篇
自动化技术   304篇
  2023年   12篇
  2022年   26篇
  2021年   23篇
  2020年   17篇
  2019年   32篇
  2018年   29篇
  2017年   30篇
  2016年   41篇
  2015年   27篇
  2014年   45篇
  2013年   136篇
  2012年   77篇
  2011年   104篇
  2010年   103篇
  2009年   82篇
  2008年   92篇
  2007年   93篇
  2006年   95篇
  2005年   88篇
  2004年   56篇
  2003年   53篇
  2002年   43篇
  2001年   30篇
  2000年   23篇
  1999年   30篇
  1998年   45篇
  1997年   42篇
  1996年   33篇
  1995年   29篇
  1994年   21篇
  1993年   30篇
  1992年   28篇
  1991年   9篇
  1990年   22篇
  1989年   22篇
  1988年   21篇
  1987年   16篇
  1986年   18篇
  1985年   24篇
  1984年   25篇
  1983年   22篇
  1982年   10篇
  1981年   15篇
  1980年   12篇
  1979年   16篇
  1977年   15篇
  1976年   11篇
  1975年   17篇
  1970年   8篇
  1969年   8篇
排序方式: 共有1966条查询结果,搜索用时 16 毫秒
101.
Expert systems are rapidly growing in diversity of application and usage worldwide. Even though expert system development has been slow in applying expert systems to the specific field of structures, expert system technology has been pervasive in other areas of engineering and manufacturing. This paper provides a short introduction on expert systems, looking at their development, application and future trends.  相似文献   
102.
103.
Randomly assigned 48 21-56 yr. Old females to 1 of 4 groups given different information with regard to a hypnotist's warmth and experience. The 6 male graduate student hypnotists had previously been judged on their objective warmth and competent appearance. Following structuring, all ss underwent individual hypnotic induction. As predicted, ss run by the objectively warmer, more competent appearing es obtained significantly higher susceptibility scores. Structured warmth produced significant differences only in ss run by the objectively less warm es. Both structured warmth and experience affected ss' subjective impressions of whether they thought they had been hypnotized. The complex relationship between antecedent variables and the various objective and subjective dependent indicators of hypnotic phenomena are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
104.
Investigated the relationships between marital status and the incidence and prognosis of schizophrenia, based on a considerably more representative sample (N = 213) than previously available. Results provide strong evidence that the rate differentials and differences in outcome so often observed for marital status categories do not derive from inadequate or inappropriate sampling or statistical manipulation. In additional analyses, controlling for differential social class and severity of pathology, however, the relationships with prognosis could no longer be observed. These latter findings suggest that a process of selection by marriage is the more tenable interpretation of the relationships under consideration. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
105.
Finite difference treatment of two-dimensional problems in elastostatics is usually based on the differential equations for the displacement vector or the Airy stress function, depending on whether boundary conditions are on displacement or stress. In either case, determination of stresses requires numerical differentiation and therefore use of a rather fine grid. Moreover, neither method is suited to the treatment of mixed boundary conditions. The alternative method developed in this paper uses the first derivatives of the displacement components at the grid points as basic variables and hence does not require numerical differentiation in the evaluation of stresses. Appropriate finite difference equations are established, and their use is discussed in connection with a specific example with known explicit solution.  相似文献   
106.
Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent in Johne's disease in cattle and causes diarrhea, decreased milk production, emaciation, and frequently death. The ability to detect MAP rapidly and accurately is an integral part of herd management. However, detection of this bacterium is complicated due to its slow division time and its ability to enter dormancy. Culture methods are considered the "gold standard," but they have their limitations. Many enzyme-linked immunosorbent assay methods and conventional PCR methods have been used as diagnostic tools. The present study compares the results of a PCR prescreen to two culture methods of detection paired with confirmatory PCR to determine the most accurate, rapid, and sensitive method using U.S. Department of Agriculture (USDA) fecal check samples. This study involving two laboratories (Marshfield Clinic Laboratories, using solid culture medium [Herrold's egg yolk agar], and TREK Diagnostic Systems Research and Development, using liquid culture medium [ESP Culture System II]) showed that the PCR prescreening method used in this study lacked specificity and sensitivity as a stand-alone test in fecal samples. However, the combination of liquid enrichment culture using the ESP II system, and PCR confirmation with the hspX primer set, was not only 100% sensitive and specific but also correlated with viable MAP and USDA culture results.  相似文献   
107.
Journal of the American Oil Chemists' Society - A dynamic foam test for evaluation of hand-dish-washing compositions has been developed which gives good correlation with semipractical plate...  相似文献   
108.
Blind deblurring of spiral CT images   总被引:7,自引:0,他引:7  
To discriminate fine anatomical features in the inner ear, it has been desirable that spiral computed tomography (CT) may perform beyond their current resolution limits with the aid of digital image processing techniques. In this paper, we develop a blind deblurring approach to enhance image resolution retrospectively without complete knowledge of the underlying point spread function (PSF). An oblique CT image can be approximated as the convolution of an isotropic Gaussian PSF and the actual cross section. Practically, the parameter of the PSF is often unavailable. Hence, estimation of the parameter for the underlying PSF is crucially important for blind image deblurring. Based on the iterative deblurring theory, we formulate an edge-to-noise ratio (ENR) to characterize the image quality change due to deblurring. Our blind deblurring algorithm estimates the parameter of the PSF by maximizing the ENR, and deblurs images. In the phantom studies, the blind deblurring algorithm reduces image blurring by about 24%, according to our blurring residual measure. Also, the blind deblurring algorithm works well in patient studies. After fully automatic blind deblurring, the conspicuity of the submillimeter features of the cochlea is substantially improved.  相似文献   
109.

Volume Contents

Contents of Volume 111 (2001)  相似文献   
110.
Mechanical flexing of plastic substrates coated with thin film permeation barriers causes stress-induced cracks that may lead to device degradation. This phenomenon is of particular importance for organic light emitting diodes, an emerging display technology that can be implemented on flexible substrates but imposes stringent requirements on the barrier performance. We demonstrate a dry-etch-based method to highlight cracks in thin films of transparent materials and make them visible under a conventional optical microscope on samples in a neutral, relaxed position. This approach allows for rapid evaluation of the mechanical performance of thin film barriers on flexible substrates.  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