全文获取类型
收费全文 | 265421篇 |
免费 | 29186篇 |
国内免费 | 9149篇 |
专业分类
电工技术 | 13146篇 |
技术理论 | 24篇 |
综合类 | 14164篇 |
化学工业 | 54671篇 |
金属工艺 | 13450篇 |
机械仪表 | 15218篇 |
建筑科学 | 19221篇 |
矿业工程 | 7504篇 |
能源动力 | 7192篇 |
轻工业 | 20185篇 |
水利工程 | 3871篇 |
石油天然气 | 16665篇 |
武器工业 | 1647篇 |
无线电 | 31353篇 |
一般工业技术 | 37596篇 |
冶金工业 | 13454篇 |
原子能技术 | 2264篇 |
自动化技术 | 32131篇 |
出版年
2024年 | 994篇 |
2023年 | 3801篇 |
2022年 | 6485篇 |
2021年 | 9281篇 |
2020年 | 8323篇 |
2019年 | 8776篇 |
2018年 | 9476篇 |
2017年 | 10607篇 |
2016年 | 10250篇 |
2015年 | 12463篇 |
2014年 | 14817篇 |
2013年 | 17917篇 |
2012年 | 16685篇 |
2011年 | 17587篇 |
2010年 | 15849篇 |
2009年 | 14992篇 |
2008年 | 14254篇 |
2007年 | 13609篇 |
2006年 | 13919篇 |
2005年 | 12052篇 |
2004年 | 8561篇 |
2003年 | 7489篇 |
2002年 | 6708篇 |
2001年 | 5970篇 |
2000年 | 6486篇 |
1999年 | 6898篇 |
1998年 | 5551篇 |
1997年 | 4517篇 |
1996年 | 4238篇 |
1995年 | 3545篇 |
1994年 | 2841篇 |
1993年 | 1996篇 |
1992年 | 1558篇 |
1991年 | 1245篇 |
1990年 | 952篇 |
1989年 | 757篇 |
1988年 | 549篇 |
1987年 | 345篇 |
1986年 | 294篇 |
1985年 | 212篇 |
1984年 | 151篇 |
1983年 | 130篇 |
1982年 | 133篇 |
1981年 | 106篇 |
1980年 | 87篇 |
1979年 | 46篇 |
1978年 | 31篇 |
1977年 | 25篇 |
1976年 | 50篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Two kinds of biosensors for amino acids (one with nonspecific enzyme as bioelement, the other with specific enzyme(s) as bioelement),
including their principles, applications, recent researches and future trends were discussed in detail. 61 references were
given.
A part of work for gaining Ph. D in chemical and biochemical application at FPMs (Mons, Belgique)
Synopsis of the first author Xia Jinlan, Male, born in 1963, now at Facult’e Polytechnique de Mons, Belgique 相似文献
103.
Liu Y. Blostein S.D. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1992,38(1):177-182
Bayesian analysis is used to show that Wald's sequential probability ratio test with varying thresholds is optimal for the nonstationary situation, where the observed samples are independent but not identically distributed. Some important properties useful for the design of the test thresholds are discussed. Wald's lower bound, generalized to the nonstationary situation, is also presented. The results have important applications in situations where the observed signal is time-varying. such as in radar signal processing, image processing, and spread spectrum communications 相似文献
104.
J. Weise Dr.‐Ing. O. Yezerska M. Busse M. Haesche V. Zanetti‐Bueckmann M. Schmitt 《Materialwissenschaft und Werkstofftechnik》2007,38(11):901-906
Micro‐porous syntactic foams were produced by means of integration of glass bubbles into aluminium and zinc matrices. Preforms of glass bubbles were pressure infiltrated with the alloys AlSi9Cu9 ans ZnAl4Cu using squeeze casting. The preforms were sintered thermically without the use of bonding agents. Using the combination of different sintering steps syntactic foams with locally different densities could be produced. The mechanical properties of the foams were tested indicating a high compression strength of the foams and a very good compression energy absorption. Furthermore, corrosion behaviour and behaviour at higher temperatures were investigated. 相似文献
105.
We define the very rich language of composed conditionals on a three‐valued logic and use this language as the communication tool between man and machine. Communication takes place for three reasons: knowledge acquisition, query, and response. Learning, thinking, and answering questions are of a pure information theoretical nature. The pivot of this knowledge processing concept is the amount of information (bit) we receive if a conditional becomes true. We follow an axiomatic approach to information theory rather than the classical probabilistic approach of Shannon; information comes first, and then comes probability. In the light of this philosophy, query and response experience new interpretations. Both, acquisition and response are realized by maximizing entropy and minimizing relative entropy, respectively. The iterative solution of these mathematical optimization problems gives new insights into the adaptation of prior knowledge to new information. Our expert system shell SPIRIT supports this kind of knowledge processing, which will be established by suitable examples. © 2003 Wiley Periodicals, Inc. 相似文献
106.
Methods of optimizing the design of electrical machines are discussed. The augmented Lagrangian multiplier method is described, and an algorithm for this method is introduced. The method is compared with the more familiar exterior penalty function method using, as an example, the cost optimization of permanent magnetic variable-speed drive motors. The improved method is shown to be superior, both in its ability to reach an optimum consistently and in the number of required iterations 相似文献
107.
Wood has long traditions as a building material, and is often used in construction elements, and as interior and exterior surfaces in the Nordic countries. In most applications, there are reaction to fire requirements to products used as surfaces, e.g. in escape routes and larger public spaces. Most wood products will therefore have to be treated with fire retardant (FR) agents to fulfil the strict requirements to properties connected to heat release and flame spread. Unfortunately, FR agents usually also increase the smoke production, as they cause a more incomplete combustion of the wood. The wood product manufacturers seek to find the optimal amount of FR additives where both heat release and smoke production in the classifying test are within the requirements given in the building regulations. This paper describes models for prediction of the European reaction to fire classes of wood products. The models are based on multivariate statistical analysis, and use test results from the cone calorimeter test as input. The presented models are, with very good precision, able to predict which Euroclass and additional smoke class a wood based product would obtain if it were to be tested in the single burning item test. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
108.
This paper examines bidding strategies in a bilateral market in which generating companies submit bids to loads. A load accepts electricity delivery from the generator with the lowest bid at its bid price as long as this price is not higher than the load's willingness to pay. Necessary and sufficient conditions of Nash equilibrium (NE) bidding strategy are derived based on a generic generating cost matrix and the loads' willingness to pay vector. The study shows that in any NE, efficient allocation is achieved. Furthermore, all Nash equilibria are revenue equivalent for the generators. Based on the necessary and sufficient conditions, this problem is formulated as an optimal assignment problem. Network optimization techniques are applied to calculate NE bid prices for the generators 相似文献
109.
HHD型核子秤电离室已成功地使用于HCS型核子秤.对它的各种物理性能指标进行了检测,各项性能指标都达到了设计要求。 相似文献
110.