全文获取类型
收费全文 | 9848篇 |
免费 | 585篇 |
国内免费 | 22篇 |
专业分类
电工技术 | 148篇 |
综合类 | 18篇 |
化学工业 | 2496篇 |
金属工艺 | 185篇 |
机械仪表 | 219篇 |
建筑科学 | 344篇 |
矿业工程 | 38篇 |
能源动力 | 244篇 |
轻工业 | 497篇 |
水利工程 | 77篇 |
石油天然气 | 32篇 |
无线电 | 863篇 |
一般工业技术 | 2383篇 |
冶金工业 | 1151篇 |
原子能技术 | 84篇 |
自动化技术 | 1676篇 |
出版年
2023年 | 156篇 |
2022年 | 382篇 |
2021年 | 427篇 |
2020年 | 292篇 |
2019年 | 263篇 |
2018年 | 322篇 |
2017年 | 275篇 |
2016年 | 357篇 |
2015年 | 314篇 |
2014年 | 469篇 |
2013年 | 596篇 |
2012年 | 569篇 |
2011年 | 653篇 |
2010年 | 448篇 |
2009年 | 458篇 |
2008年 | 460篇 |
2007年 | 440篇 |
2006年 | 350篇 |
2005年 | 272篇 |
2004年 | 242篇 |
2003年 | 223篇 |
2002年 | 221篇 |
2001年 | 150篇 |
2000年 | 127篇 |
1999年 | 135篇 |
1998年 | 265篇 |
1997年 | 192篇 |
1996年 | 136篇 |
1995年 | 96篇 |
1994年 | 93篇 |
1993年 | 104篇 |
1992年 | 62篇 |
1991年 | 57篇 |
1990年 | 56篇 |
1989年 | 48篇 |
1988年 | 52篇 |
1987年 | 49篇 |
1986年 | 37篇 |
1985年 | 46篇 |
1984年 | 41篇 |
1983年 | 34篇 |
1982年 | 34篇 |
1981年 | 35篇 |
1980年 | 25篇 |
1979年 | 25篇 |
1978年 | 31篇 |
1977年 | 28篇 |
1976年 | 68篇 |
1975年 | 30篇 |
1971年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Game AI is Dead. Long Live Game AI! 总被引:1,自引:0,他引:1
Alexander Nareyek 《Intelligent Systems, IEEE》2007,22(1):9-11
This paper discusses how the recent advances in game AI technology can help benefit industry and the academia. Some of these advances include large-scale automated art and content generation, automated storytelling, goal-driven virtual actors, and the ability to adapt to the player's preferences and mental state 相似文献
12.
E Orgnero de Gaisán C Maldonado MF Diaz Gavier A Aoki 《Canadian Metallurgical Quarterly》1997,179(5):453-460
A bioassay system for rapid detection of carcinogenic agents has been developed using male Fischer 344 rats to bridge the gap between long-term carcinogenicity tests and short-term screening assays. The system, called the medium-term liver bioassay, is fundamentally based on the 2-stage hypothesis of tumor production, employing initiation by diethylnitrosamine (200 mg/kg, i.p.) in the first stage and test chemical administration during the second, in combination with two-thirds partial hepatectomy. It requires only 8 wk for animal experimentation and a further few weeks for quantitative analysis of immunohistochemically demonstrated glutathione S-transferase placental form positive hepatic foci. A total of 291 chemicals/substances have already been analyzed in our laboratory. Among 63 chemicals that were proved to be carcinogenic in the liver of rat and/or mouse, 57 (90%) gave positive results irrespective of their mutagenicity. Negative compounds include peroxisome proliferators and tamoxifen. Even nonhepatocarcinogens were positive at a rate of 24%. Eighty-six percent (12/14) of mouse liver carcinogens were also positive. On the other hand, only 2 out of 45 noncarcinogens showed very weak positivity. Thus, the efficacy of the system for hepatocarcinogens has been well established. This bioassay is increasingly regarded as an appropriate alternative test for carcinogenicity risk assessment and is practically used for a rapid evaluation of hepatocarcinogenicity of chemicals. 相似文献
13.
14.
Grant A.J. Alexander P.D. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1998,44(7):2832-2836
The effect of using randomly selected sequence multisets for the uplink of a synchronous code-division multiple-access channel is considered. A tight lower bound on the expected value of the sum capacity over the ensemble of randomly selected sequence multisets is given. For large systems, the sum rate penalty for using randomly selected multisets is shown to be at most 1 nat and to vanish as the number of users becomes large, compared to the sequence length 相似文献
15.
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
16.
Ellen Y. Sun Kathleen B. Alexander Paul F. Becher Shyh-Lung Hwang 《Journal of the American Ceramic Society》1996,79(10):2626-2632
Interfacial microstructures in βP-Si3 N4 ( w )-Si-Al-Y-O-N-glass systems were investigated by systematically varying the nitrogen content and the Al:Y ratio of the glass matrix. High-resolution and analytical transmission electron microscopy (HREM and AEM) studies revealed that the interfacial microstructure is a function of the glass composition. No interfacial phases were formed in glasses with low Al:Y ratios and in glasses with high Al:Y ratios and low nitrogen content, whereas epitaxial growth of an interfacial layer (100–200 μm thick) on the βP-Si3 N4 ( w ) occurred in a glass matrix with high Al:Y ratio and high nitrogen content. The interfacial layer was identified to be a β'-SiAION phase. Interfaces containing the SiAION layer exhibited high debonding energy compared to Si3 N4 ( w )–glass interfaces. HREM studies indicated that the lattice-mismatch strain in the SiAION layer was relieved by dislocation formation at the SiAION–Si3 N4 ( w ) interface. The difference in interfacial debonding energy was, hence, attributed to the local atomic structure and bonding between the glass-β-Si3 N4 and the glass–β'-SiAION phases. This observation was clear evidence of the strong influence of glass chemistry on the interfacial debonding behavior by altering the interfacial microstructure. 相似文献
17.
Collaborative work is an important part of tertiary education but it is very difficult to arrange and supervise for extremely large classes of students in their first year. The possibility that computer-mediated communication can be used to facilitate this type of learning is appealing from a pragmatic organisational point of view. This paper explains in detail what a ‘virtual team’ is in the educational context. It reports on an interpretive field study where students taking an introductory course were allowed to choose where and when they did the required collaborative work. The paper discusses the factors that should be taken into account when offering students the option of working as a virtual team. These include factors that influence the students’ choice. The project cannot be considered to have been successful but indicates reasons for the lack of success and suggests contexts in which it would be valuable to repeat the project. The importance of extensive preparation in terms of teaching the students necessary social and technological skills cannot be over emphasised. 相似文献
18.
Staub Adrian; Rayner Keith; Pollatsek Alexander; Hy?n? Jukka; Majewski Helen 《Canadian Metallurgical Quarterly》2007,33(6):1162
Readers' eye movements were monitored as they read sentences containing noun-noun compounds that varied in frequency (e.g., elevator mechanic, mountain lion). The left constituent of the compound was either plausible or implausible as a head noun at the point at which it appeared, whereas the compound as a whole was always plausible. When the head noun analysis of the left constituent was implausible, reading times on this word were inflated, beginning with the first fixation. This finding is consistent with previous demonstrations of very rapid effects of plausibility on eye movements. Compound frequency did not modulate the plausibility effect, and all disruption was resolved by the time readers' eyes moved to the next word. These findings suggest (contra Kennison, 2005) that the parser initially analyzes a singular noun as a head instead of a modifier. In addition, the findings confirm that the very rapid effect of plausibility on eye movements is not due to strategic factors, because in the present experiment, unlike in previous demonstrations, this effect appeared in sentences that were globally plausible. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
Gkatzianas M.A. Balanis C.A. Diaz R.E. 《Microwave and Wireless Components Letters, IEEE》2004,14(5):219-221
This paper proposes an alternative expression for the in-cell capacitance of a photoelectrical cell (PEC)-mounted slot, which is the conceptual cornerstone of the Gilbert-Holland subcell finite difference time domain (FDTD) model. By treating a slightly modified electrostatic problem, the extraneous charge singularity on the PEC edges touching the cell, which is characteristic of the originally proposed model, is removed. The latter offers better physical grounds for a new expression of the capacitance and the effective permittivity used in the update equations. High resolution standard FDTD simulation results are presented in support of the new expression. 相似文献
20.