全文获取类型
收费全文 | 1340篇 |
免费 | 30篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 232篇 |
金属工艺 | 13篇 |
机械仪表 | 20篇 |
建筑科学 | 52篇 |
矿业工程 | 5篇 |
能源动力 | 35篇 |
轻工业 | 119篇 |
水利工程 | 12篇 |
石油天然气 | 3篇 |
无线电 | 126篇 |
一般工业技术 | 203篇 |
冶金工业 | 311篇 |
原子能技术 | 11篇 |
自动化技术 | 212篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 11篇 |
2019年 | 16篇 |
2018年 | 19篇 |
2017年 | 13篇 |
2016年 | 27篇 |
2015年 | 24篇 |
2014年 | 44篇 |
2013年 | 45篇 |
2012年 | 42篇 |
2011年 | 60篇 |
2010年 | 62篇 |
2009年 | 39篇 |
2008年 | 58篇 |
2007年 | 55篇 |
2006年 | 36篇 |
2005年 | 41篇 |
2004年 | 25篇 |
2003年 | 34篇 |
2002年 | 29篇 |
2001年 | 30篇 |
2000年 | 23篇 |
1999年 | 22篇 |
1998年 | 97篇 |
1997年 | 77篇 |
1996年 | 47篇 |
1995年 | 19篇 |
1994年 | 26篇 |
1993年 | 22篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 11篇 |
1986年 | 17篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 26篇 |
1976年 | 23篇 |
1975年 | 9篇 |
1970年 | 8篇 |
1967年 | 6篇 |
排序方式: 共有1371条查询结果,搜索用时 0 毫秒
101.
102.
From Images to Shape Models for Object Detection 总被引:2,自引:0,他引:2
Vittorio Ferrari Frederic Jurie Cordelia Schmid 《International Journal of Computer Vision》2010,87(3):284-303
We present an object class detection approach which fully integrates the complementary strengths offered by shape matchers.
Like an object detector, it can learn class models directly from images, and can localize novel instances in the presence
of intra-class variations, clutter, and scale changes. Like a shape matcher, it finds the boundaries of objects, rather than
just their bounding-boxes. This is achieved by a novel technique for learning a shape model of an object class given images of example instances. Furthermore, we also integrate Hough-style voting with a non-rigid point matching algorithm to localize
the model in cluttered images. As demonstrated by an extensive evaluation, our method can localize object boundaries accurately
and does not need segmented examples for training (only bounding-boxes). 相似文献
103.
Silver (Ag) and copper (Cu) are regarded as advanced material for metallization systems in microelectronic devices because of their high electrical conductivity and enhanced electromigration resistance. Typically, organic circuit boards as well as ceramic and glass–ceramic substrates use galvanic deposited Cu films or screen-printed metallization for this purpose. When applying the latter approach, however, the lateral resolution in the μm-region being required e.g. for novel high frequency applications can not be guaranteed. Hence, sputter deposition is envisaged for the realization of thin film metallization systems. The reliability of 300?nm thick Cu and Ag thin films is comparatively investigated under accelerated aging conditions, utilizing a test structure which consists of parallel lines stressed with current densities up to 2.5?×?106?A?cm?2 at temperatures up to 300°C on Si/SiO2, glass, LTCC (low temperature co-fired ceramics) and alumina substrates. To detect the degradation via the temporal characteristics of the current signal a constant voltage is applied according to the overall resistance of the test structure. Knowing the mean time to failure (MTF) and the activation energy at elevated temperatures conclusions on the migration mechanism can be drawn. Whereas on LTCC substrates the activation energy Ea is about 0.75?eV for both Ag and Cu thin films, the higher activation energies of about Ea?~?1?eV measured for Cu on glass and alumina indicate a suppression of back diffusion especially at enhanced temperature levels. This effect is predominantly caused by a stable oxide layer which is formed at high temperatures and which acts as passivation layer. Therefore, the overall electromigration resistance is lower compared to Ag. 相似文献
104.
We present a technique for inducing functional programs from few, well chosen input/output-examples (I/O-examples). Potential applications for automatic program or algorithm induction are to enable end users to create their own simple programs, to assist professional programmers, or to automatically invent completely new and efficient algorithms. In our approach, functional programs are represented as constructor term rewriting systems (CSs) containing recursive rules. I/O-examples for a target function to be implemented are a set of pairs of terms (F(ii),oi) meaning that F(ii)—denoting application of function F to input ii—is rewritten to oi by a CS implementing the function F. Induction is based on detecting syntactic regularities between example terms. In this paper we present theoretical results and describe an algorithm for inducing CSs over arbitrary signatures/data types which consist of one function defined by an arbitrary number of rules with an arbitrary number of non-nested recursive calls in each rule. Moreover, we present empirical results based on a prototypical implementation. 相似文献
105.
Robert Schmid 《Automatica》2007,43(9):1666-1669
The papers by Xu and Tan [Robust optimal design and convergence properties analysis of iterative learning control approaches, Automatica 38 (2002) 1867-1880], and Xu and Tan [On the P-type and Newton-type ILC schemes for dynamic systems with non-affine input factors, Automatica 38 (2002) 1237-1242], give a convergence analysis for several iterative learning control approaches. Unfortunately, these papers contains several mathematical errors that render the proofs of the claimed results invalid. As there are no obvious ways to correct these errors, the results presented in these papers are questionable. 相似文献
106.
A remotely steered millimetre wave launcher for electron cyclotron heating and current drive on ITER
W.A. Bongers M.F. Graswinckel W. Kasparek Á. Fernández Curto M.A. van den Berg B.S.Q. Elzendoorn P. Ivanov B. Lamers B. Piosczyk D.M.S. Ronden M. Schmid 《Fusion Engineering and Design》2010,85(1):69-86
High-power millimetre wave beams employed on ITER for heating and current drive at the 170 GHz electron cyclotron resonance frequency require agile steering and tight focusing of the beams to suppress neoclassical tearing modes. This paper presents experimental validation of the remote steering (RS) concept of the ITER upper port millimetre wave beam launcher. Remote steering at the entrance of the upper port launcher rather than at the plasma side offers advantages in reliability and maintenance of the mechanically vulnerable steering system. A one-to-one scale mock-up consisting of a transmission line, mitre bends, remote steering unit, vacuum window, square corrugated waveguide and front mirror simulates the ITER launcher design configuration. Validation is based on low-power heterodyne measurements of the complex amplitude and phase distribution of the steered Gaussian beam. High-power (400 kW) short pulse (10 ms) operation under vacuum, diagnosed by calorimetry and thermography of the near- and far-field beam patterns, confirms high-power operation, but shows increased power loss attributed to deteriorating input beam quality compared with low-power operation. Polarization measurements show little variation with steering, which is important for effective current drive requiring elliptical polarization for O-mode excitation. Results show that a RS range of up to −12° to +12° can be achieved with acceptable beam quality. These measurements confirm the back-up design of the ITER ECRH&CD launcher with future application for DEMO. 相似文献
107.
It still is a challenging development goal to improve sizing of di discontinuities by using NDT, since essential characteristics, as for instance crack depth extension, in many cases only can be evaluated within the scope of a large scale measurement: New NDT-techniques such as specially designed UT-probes to suit the test problem, and also a substantially extended theoretical background contribute to reliable statements concerning crack depth.The development of imaging UT-reconstruction methods will help to improve this situation. Practical experience with genuine testing problems are needed to judge the evidence of these methods. Experience with manual crack depth measurements is quite useful to create a practicable and reliable instrument based on reconstruction methods. 相似文献
108.
109.
110.
Schmid M. Weber R. Graf T. Roos M. Weber H.P. 《Quantum Electronics, IEEE Journal of》2000,36(5):620-626
The results of numerical simulations based on finite-element methods for thermally induced birefringence in Nd:YAG crystal rods are compared with measurements and analytical solutions. A novel analytical solution for inhomogeneous pumping is presented. It is shown that the behavior of thermally induced birefringence is very sensitive to the pump geometry 相似文献