全文获取类型
收费全文 | 1599篇 |
免费 | 50篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 480篇 |
金属工艺 | 33篇 |
机械仪表 | 9篇 |
建筑科学 | 64篇 |
矿业工程 | 2篇 |
能源动力 | 32篇 |
轻工业 | 172篇 |
水利工程 | 10篇 |
石油天然气 | 8篇 |
无线电 | 166篇 |
一般工业技术 | 301篇 |
冶金工业 | 143篇 |
原子能技术 | 13篇 |
自动化技术 | 212篇 |
出版年
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 10篇 |
2019年 | 13篇 |
2018年 | 19篇 |
2017年 | 25篇 |
2016年 | 26篇 |
2015年 | 26篇 |
2014年 | 41篇 |
2013年 | 87篇 |
2012年 | 58篇 |
2011年 | 97篇 |
2010年 | 67篇 |
2009年 | 70篇 |
2008年 | 91篇 |
2007年 | 64篇 |
2006年 | 71篇 |
2005年 | 52篇 |
2004年 | 62篇 |
2003年 | 52篇 |
2002年 | 69篇 |
2001年 | 32篇 |
2000年 | 32篇 |
1999年 | 36篇 |
1998年 | 32篇 |
1997年 | 20篇 |
1996年 | 25篇 |
1995年 | 24篇 |
1994年 | 26篇 |
1993年 | 25篇 |
1992年 | 24篇 |
1991年 | 16篇 |
1990年 | 18篇 |
1989年 | 23篇 |
1988年 | 19篇 |
1987年 | 15篇 |
1986年 | 16篇 |
1985年 | 30篇 |
1984年 | 13篇 |
1983年 | 23篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 15篇 |
1976年 | 16篇 |
1975年 | 20篇 |
1974年 | 10篇 |
1966年 | 7篇 |
排序方式: 共有1659条查询结果,搜索用时 15 毫秒
91.
Quang Huy Nguyen Claude Kirchner Hélène Kirchner 《Journal of Automated Reasoning》2002,29(3-4):309-336
This paper presents the design, the implementation, and experiments of the integration of syntactic, conditional possibly associative-commutative term rewriting into proof assistants based on constructive type theory. Our approach is called external because it consists in performing term rewriting in a specific and efficient environment and checking the computations later in a proof assistant. Two typical systems are considered in this work: ELAN, based on the rewriting calculus, as the term rewriting-based environment, and Coq, based on the calculus of inductive constructions as the proof assistant. We first formalize the proof terms for deduction by rewriting and strategies in ELAN using the rewriting calculus with explicit substitutions. We then show how these proof terms can soundly be translated into Coq syntax where they can be directly type checked. For the method to be applicable for rewriting modulo associativity and commutativity, we provide an effective method to prove equalities modulo these axioms in Coq using ELAN. These results have been integrated into an ELAN-based rewriting tactic in Coq. 相似文献
92.
TGV: theory, principles and algorithms 总被引:3,自引:0,他引:3
Claude Jard Thierry Jéron 《International Journal on Software Tools for Technology Transfer (STTT)》2005,7(4):297-315
This paper presents the TGV tool, which allows for the automatic synthesis of conformance test cases from a formal specification of a (non-deterministic) reactive system. TGV was developed by Irisa Rennes and Verimag Grenoble, with the support of the Vasy team of Inria Rhônes-Alpes. The paper describes the main elements of the underlying testing theory, which is based on a model of transitions system which distinguishes inputs, outputs and internal actions, and is based on the concept of conformance relation. The principles of the test synthesis process, as well as the main algorithms, are explained. We then describe the main characteristics of the TGV tool and refer to some industrial experiments that have been conducted to validate the approach. As a conclusion, we describe some ongoing work on test synthesis. 相似文献
93.
Eric Cancès Claude LeBris Yvon Maday Gabriel Turinici 《Journal of scientific computing》2002,17(1-4):461-469
Due to the high dimensionality of the spaces where the problems are set, adapted discretization basis are often advocated in complex physical problems (Navier–Stokes equations, solid mecanics, ab initio electronic structure computations) to express the solution in terms of solution of similar (but easier to solve) problems. However, very few mathematical studies have been undertaken to asses the numerical properties of these approximations. Within this context, we will present in this paper an overview of the tools required to develop more rigorous reduced basis approaches for quantum chemistry: a posteriori numerical analysis and fast exponential decay of the n-width of the solution set. 相似文献
94.
95.
A prototype, all-sky flux mapper has been developed at the Solar Energy Research Institute (SERI). The flux mapper is a video system which provides a rapid, real time processing of daylightning luminance data. The system uses an orthographic-projection fish-eye lens to project the entire image of a 180° field onto a vidicon target. The signal is then digitized and may be plotted as equal brightness comtours or recorded on tape for later analysis. The system has great potential for use in delineating illuminance distribution of the sky and of interior spaces. 相似文献
96.
The radiosity method is particularly suitable for global illumination calculations in static environments. Nonetheless, recent applications of image synthesis such as architectural simulation or lighting design require the ability to modify environments. Previous methods have attempted to deal with dynamic environments (environments where the geometry, the material properties, etc., can change)but still suffer some limitations in the case of moving objects. One of the main problems remaining is the efficient and accurate detection of which form factors must really be recomputed, since their calculation is the most time-consuming part of the radiosity method. To correctly understand and solve this problem, we start with a method in 2D for polygonal scenes using the visibility complex. It is a powerful data structure representing the visibility relationships between objects in the plane. We have developed and implemented an algorithm which uses this structure to efficiently compute the discontinuity mesh and the form factors for static scenes. We also propose an extension to our algorithm to efficiently update only the modified form factors when an object is moving. This approach enhances our understanding and will hopefully lead to efficient solutions in 3D. 相似文献
97.
The authors have treated a statistical model which describes time intervals distribution between successive echos scattered by a fluctuating surface. A sonar signal scattered by sea surface is taken as a practical example. It is shown that scattered echos are achieved by random deleting of transmitted signals. 相似文献
98.
Adult male Ithomiinae feed at plants containing pyrrolizidine alkaloids. Certain species secrete on hairs of the costal fringe, a specialized organ on their hindwings, a novel -lactone structurally related to the unusual branched-chain acids that are unique to these alkaloids. 相似文献
99.
Summary Poly(-malic acid) is a new synthetic functional polyester of the poly(-hydroxy-acid)-type whose properties are investigated in regard to possible uses as bioresorbable polyvalent drug-carrier. Degradation of polymer chains in 0.15 N phosphate buffer at pH=7.5 is monitored by aqueous GPC on SEPHADEX gels and by enzymatic titration of ultimate degradation products. It is shown that the rate of degradation obeys first order kinetics at the begining and that poly(-malic acid) degrades to malic acid at last.Presented at the 26th IUPAC Microsymposium on Macromolecules: Polymers in Medicine and Biology, Prague, July 9–12, 1984 相似文献
100.
Cathignol Dominique J. Fourcade Claude Chapelon Jean-Yvey 《IEEE transactions on bio-medical engineering》1980,(1):30-36
In order to obviate the limitations of the conventional coherent ultrasonic Doppler flowmeters we have developed a new device. In this apparatus the continuous wave is replaced by a pseudorandom signal. We show, both theoretically (Waag et al. [12]) and experimentally, that the pseudorandom system offers advantages. The most important result concerns the improvement of the signal-to-noise ratio which can be as large as 20 dB. Furthermore, it is possible to decrease the frequency and the distance ambiguity by a factor of two. Compared to the "random noise flowmeter" (Newhouse et al. [7], Jethwa et al. [5]) our system measures flow near the wall of vessels or in ultrasonic field in which there are important fixed echoes. To illustrate the feasibility of this new device, we show some results obtained by the transcutaneous method. 相似文献