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   19124篇
  免费   321篇
  国内免费   36篇
电工技术   222篇
综合类   18篇
化学工业   2162篇
金属工艺   292篇
机械仪表   341篇
建筑科学   561篇
矿业工程   24篇
能源动力   274篇
轻工业   1791篇
水利工程   121篇
石油天然气   32篇
无线电   1541篇
一般工业技术   2162篇
冶金工业   7869篇
原子能技术   176篇
自动化技术   1895篇
  2023年   49篇
  2022年   134篇
  2021年   238篇
  2020年   127篇
  2019年   194篇
  2018年   235篇
  2017年   223篇
  2016年   266篇
  2015年   160篇
  2014年   310篇
  2013年   668篇
  2012年   512篇
  2011年   663篇
  2010年   509篇
  2009年   507篇
  2008年   584篇
  2007年   574篇
  2006年   469篇
  2005年   469篇
  2004年   375篇
  2003年   384篇
  2002年   341篇
  2001年   334篇
  2000年   320篇
  1999年   489篇
  1998年   2474篇
  1997年   1547篇
  1996年   1007篇
  1995年   660篇
  1994年   547篇
  1993年   598篇
  1992年   214篇
  1991年   191篇
  1990年   219篇
  1989年   214篇
  1988年   220篇
  1987年   168篇
  1986年   172篇
  1985年   219篇
  1984年   126篇
  1983年   111篇
  1982年   102篇
  1981年   132篇
  1980年   132篇
  1979年   97篇
  1978年   57篇
  1977年   239篇
  1976年   414篇
  1975年   65篇
  1973年   64篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Proteomics has long been thought to hold the promise of producing results of clinical utility which will influence patient treatment and outcomes. A recent Wellcome Trust/EBI meeting and retreat--“Perspectives in Clinical Proteomics”--brought together experts from a broad range of stakeholder groups with an interest in ensuring proteomics achieves this aim. This viewpoint presents views derived from these forums, proposing a pathway for the development of next-generation proteomic analyses in the clinical setting from selection of candidates through to their validation and ultimate demonstration of utility through health technology assessments. Although not meant to be all encompassing, important elements for proteomics researchers to consider are presented.  相似文献   
72.
A gas-jet micro pump with novel cross-junction channel has been designed and fabricated using a Si micromachining process. The valveless micro pump is composed of a piezoelectric lead zirconate titanate (PZT) diaphragm actuator and fluidic network. The design of the valveless pump focuses on a cross-junction formed by the neck of the pump chamber and one outlet and two opposite inlet channels. The structure of cross-junction allows differences in fluidic resistance and fluidic momentum inside the channels during each PZT diaphragm vibration cycle, which leads to the gas flow being rectified without valves. The flow channels were easily fabricated by using silicon etching process. To investigate the effects of the structure of the cross-junction on the gas flow rate, two types of pump with different cross-junction were studied. The design and simulation were done using ANSYS-Fluent software. The simulations and experimental data revealed that the step-nozzle structure is much more advantageous than the planar structure. A flow rate of 5.2 ml/min was obtained for the pump with step structure when the pump was driven at its resonant frequency of 7.9 kHz by a sinusoidal voltage of 50 Vp–p.  相似文献   
73.
74.
By exploiting a networked virtual environment architecture, we produced the gaming part of an interactive television drama series, TypoToons. For decades TV show makers have been inventing tools and tricks to enhance the stories they tell. Equivalents of, and additions to these conventional tricks in interactive media can only mature an interactive television if multidisciplinary teams can obtain hands on experience of these newly emerging worlds. The production team for TypoToons and the interactively participating audience provided an excellent opportunity to develop such a team  相似文献   
75.
Abstract The Virtual Constructing Tool (VCT) was developed at the Nijmegen School of Management in 1998. The VCT is intended to facilitate the process of writing group papers through the use of construction and communication tools and is based completely on the Internet. The VCT allows a paper to be structured by means of hyperlinking and cooperation between students. Students are allowed to divide tasks, but they are held responsible for the quality of the arguments in the paper as a whole. They are invited to spend time in dealing with validity claims and in building a valid train of thought. Producing a group paper includes four interrelated working processes: exploring the subject, exchanging information, arguing and discussing and editing. Hyperlinking offers a contribution in each of these processes which varies from associative linking of pieces of information to strengthening linear structuring. Therefore, a different perspective has been taken to that of those authors who consider hyperlinking as a tool par excellence for the nonlinear production of information.  相似文献   
76.
In subspace identification methods, the system matrices are usually estimated by least squares, based on estimated Kalman filter state sequences and the observed inputs and outputs. For a finite number of data points, the estimated system matrix is not guaranteed to be stable, even when the true linear system is known to be stable. In this paper, stability is imposed by using regularization. The regularization term used here is the trace of a matrix which involves the dynamical system matrix and a positive (semi) definite weighting matrix. The amount of regularization can be determined from a generalized eigenvalue problem. The data augmentation method of Chui and Maciejowski (1996) is obtained by using specific choices for the weighting matrix in the regularization term  相似文献   
77.
78.
In this paper we discuss the potentialities of a time-coded single photon emissive imaging system for thyroid tomography. We have performed three-dimensional simulation studies in order to answer two questions: 1) does this coded aperture device produce good quality reconstructions, and 2) can the reconstruction be carried out sufficiently fast on a microcomputer. Our study leads to the conclusion that both questions can be answered affirmatively. Hence, time-coded emission tomography is a potentially useful imaging technique for diagnostic clinical practice.  相似文献   
79.
80.
We present a class of similarity measures for quantitatively comparing two strings, that is, two linearly ordered sets of elements. The strings can be of different lengths, the elements come from a single alphabet, and an element may appear any number of times. The limiting values of each measure are 0, when two completely different strings are compared, and 1, when the two strings are identical. Applications of similarity measures are numerous in nonnumerical computations, such as in heuristic search processes in associative networks, in pattern recognition and classification, in game playing programs, and in music and text analysis. We offer a number of feasible measures from among which some are discarded on plausibility grounds. One can select the measure most adequate for one's needs on the basis of a few characteristic examples of strings compared and by considering the specific requirements of the application at hand.  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