全文获取类型
收费全文 | 2200篇 |
免费 | 111篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 39篇 |
化学工业 | 419篇 |
金属工艺 | 42篇 |
机械仪表 | 32篇 |
建筑科学 | 46篇 |
矿业工程 | 3篇 |
能源动力 | 65篇 |
轻工业 | 297篇 |
水利工程 | 12篇 |
石油天然气 | 10篇 |
无线电 | 197篇 |
一般工业技术 | 330篇 |
冶金工业 | 465篇 |
原子能技术 | 8篇 |
自动化技术 | 347篇 |
出版年
2023年 | 15篇 |
2022年 | 21篇 |
2021年 | 38篇 |
2020年 | 25篇 |
2019年 | 43篇 |
2018年 | 54篇 |
2017年 | 50篇 |
2016年 | 65篇 |
2015年 | 40篇 |
2014年 | 68篇 |
2013年 | 115篇 |
2012年 | 109篇 |
2011年 | 115篇 |
2010年 | 109篇 |
2009年 | 75篇 |
2008年 | 118篇 |
2007年 | 95篇 |
2006年 | 94篇 |
2005年 | 86篇 |
2004年 | 73篇 |
2003年 | 58篇 |
2002年 | 52篇 |
2001年 | 45篇 |
2000年 | 40篇 |
1999年 | 51篇 |
1998年 | 120篇 |
1997年 | 77篇 |
1996年 | 58篇 |
1995年 | 33篇 |
1994年 | 30篇 |
1993年 | 41篇 |
1992年 | 19篇 |
1991年 | 18篇 |
1990年 | 22篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 19篇 |
1984年 | 21篇 |
1983年 | 23篇 |
1982年 | 11篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1976年 | 15篇 |
1974年 | 8篇 |
1973年 | 7篇 |
1972年 | 5篇 |
排序方式: 共有2312条查询结果,搜索用时 31 毫秒
1.
Varani L. Reggiani L. Kuhn T. Gonzalez T. Pardo D. 《Electron Devices, IEEE Transactions on》1994,41(11):1916-1925
We present a microscopic interpretation of electronic noise in semiconductor materials and two-terminal devices. The theory is based on Monte Carlo simulations of the carrier motion self-consistently coupled with a Poisson solver. Current and voltage noise operations are applied and their respective representations discussed. As application we consider the cases of homogeneous materials, resistors, n+nn + structures, and Schottky-barrier diodes. Phenomena associated with coupling between fluctuations in carrier velocity and self-consistent electric field are quantitatively investigated for the first time. At increasing applied fields hot-carrier effects are found to be of relevant importance in all the cases considered here. As a general result, noise spectroscopy is found to be a source of valuable information to investigate and characterize transport properties of semiconductor materials and devices 相似文献
2.
This paper looks at the concepts of entities, identities, identifiers and credentials, their definitions, and how they combine
to authenticate an identity to an account, or function, within a service. Credentials can be divided into several different
types on the basis of their use, origin and characteristics. In particular, types such as composite, dynamic and derived credentials
will be considered, and their applicability within an identity management system. Each credential must be managed through
its entire life cycle from initial registration, general use and suspension, to deletion. The notion of public (i.e. freely
distributable) and private (i.e. known only to you) aspects of a credential is explored. The bindings, by trusted third parties,
of identifiers and public credentials into permits and instruments of proof is explained along with the convenience, but greater
exposure, of local information. Several scenarios are analysed in terms of how different types of credentials are employed
during the authentication process. 相似文献
3.
O Bernard B Chachuat A Hélias B Le Dantec B Sialve J-P Steyer L Lardon P Neveu S Lambert J Gallop M Dixon P Ratini A Quintabà S Frattesi J M Lema E Roca G Ruiz J Rodriguez A Franco P Vanrolleghem U Zaher D J W De Pauw K De Neve K Lievens D Dochaine O Schoefs H Fibrianto R Farina V Alcaraz Gonzalez V Gonzalez Alvarez P Lemaire J A Martinez F Esandi O Duclaud J F Lavigne 《Water science and technology》2005,52(1-2):457-464
The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem. 相似文献
4.
Penedo Frank J.; Dahn Jason R.; Gonzalez Jeffrey S.; Molton Ivan; Carver Charles S.; Antoni Michael H.; Roos Bernard A.; Schneiderman Neil 《Canadian Metallurgical Quarterly》2003,22(2):220
This study evaluated relations among optimism, perceived stress management skills (PSMS), and positive mood in 46 men who had surgical treatment for localized prostate cancer. The authors found that optimism, PSMS, and positive mood scores were positively correlated. Positive mood was unrelated to demographic and disease-related control variables. In a hierarchical regression model controlling for PSMS, the relationship between optimism and positive mood became nonsignificant, whereas PSMS remained a correlate of positive mood. Results suggest that the relationship between optimism and positive mood may be mediated by belief in being able to use stress management techniques effectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
6.
Gonzalez A. Valero-Garcia M. Diaz de Cerio L. 《Parallel and Distributed Systems, IEEE Transactions on》1995,6(8):803-814
Many parallel algorithms use hypercubes as the communication topology among their processes. When such algorithms are executed on hypercube multicomputers the communication cost is kept minimum since processes can be allocated to processors in such a way that only communication between neighbor processors is required. However, the scalability of hypercube multicomputers is constrained by the fact that the interconnection cost-per-node increases with the total number of nodes. From scalability point of view, meshes and toruses are more interesting classes of interconnection topologies. This paper focuses on the execution of algorithms with hypercube communication topology on multicomputers with mesh or torus interconnection topologies. The proposed approach is based on looking at different embeddings of hypercube graphs onto mesh or torus graphs. The paper concentrates on toruses since an already known embedding, which is called standard embedding, is optimal for meshes. In this paper, an embedding of hypercubes onto toruses of any given dimension is proposed. This novel embedding is called xor embedding. The paper presents a set of performance figures for both the standard and the xor embeddings and shows that the latter outperforms the former for any torus. In addition, it is proven that for a one-dimensional torus (a ring) the xor embedding is optimal in the sense that it minimizes the execution time of a class of parallel algorithms with hypercube topology. This class of algorithms is frequently found in real applications, such as FFT and some class of sorting algorithms 相似文献
7.
Borman Walter C.; Hanson Mary Ann; Oppler Scott H.; Pulakos Elaine D.; White Leonard A. 《Canadian Metallurgical Quarterly》1993,78(3):443
Explores the role of early supervisory experience and cognitive ability in 1st-line supervisor performance. Similar to the F. L. Schmidt et al (see record 1986-31441-001) study of nonsupervisors, this research tested structural models hypothesizing relationships among supervisory experience, cognitive ability, supervisory knowledge and proficiency, and performance ratings, using a sample of 570 2nd-tour soldiers. The Schmidt et al model with an additional ability?→?experience path provided the best fit. The significant ability?→?experience path was interpreted as indicating that demonstrated ability contributes to soldiers being given the opportunity to obtain supervisory experience. Experience had a greater impact on supervisor proficiency than on supervisor knowledge. Ability had a greater impact on supervisor knowledge than on proficiency. Discussion focuses on the personal characteristics that might be involved in being assigned supervisory responsibilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
One reason for the limited attention to existential psychology in child treatment is the assumption that children are restricted in the amount of freedom and responsibility they can assume. However, current research on child development reveals that children actively influence their social and physical environment and hence begin from birth the process of self-determination. This article presents guidelines for implementing existential psychology with children derived from theoretical tenets and case study findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
M. Grana A. D'Anjou F.X. Albizuri M. Hernandez F.J. Torrealdea A. de la Hera A.I. Gonzalez 《Applied Intelligence》1997,7(4):287-303
This work reports the results obtained with the application of High Order Boltzmann Machines without hidden units to construct classifiers for some problems that represent different learning paradigms. The Boltzmann Machine weight updating algorithm remains the same even when some of the units can take values in a discrete set or in a continuous interval. The absence of hidden units and the restriction to classification problems allows for the estimation of the connection statistics, without the computational cost involved in the application of simulated annealing. In this setting, the learning process can be sped up several orders of magnitude with no appreciable loss of quality of the results obtained. 相似文献
10.