全文获取类型
收费全文 | 8556篇 |
免费 | 1040篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 113篇 |
综合类 | 4篇 |
化学工业 | 2380篇 |
金属工艺 | 263篇 |
机械仪表 | 459篇 |
建筑科学 | 182篇 |
矿业工程 | 7篇 |
能源动力 | 377篇 |
轻工业 | 1082篇 |
水利工程 | 40篇 |
石油天然气 | 13篇 |
无线电 | 1217篇 |
一般工业技术 | 1993篇 |
冶金工业 | 379篇 |
原子能技术 | 101篇 |
自动化技术 | 1007篇 |
出版年
2024年 | 10篇 |
2023年 | 116篇 |
2022年 | 189篇 |
2021年 | 347篇 |
2020年 | 283篇 |
2019年 | 338篇 |
2018年 | 399篇 |
2017年 | 418篇 |
2016年 | 515篇 |
2015年 | 382篇 |
2014年 | 521篇 |
2013年 | 662篇 |
2012年 | 677篇 |
2011年 | 771篇 |
2010年 | 548篇 |
2009年 | 516篇 |
2008年 | 441篇 |
2007年 | 376篇 |
2006年 | 283篇 |
2005年 | 232篇 |
2004年 | 210篇 |
2003年 | 186篇 |
2002年 | 178篇 |
2001年 | 164篇 |
2000年 | 135篇 |
1999年 | 119篇 |
1998年 | 121篇 |
1997年 | 77篇 |
1996年 | 69篇 |
1995年 | 49篇 |
1994年 | 38篇 |
1993年 | 27篇 |
1992年 | 33篇 |
1991年 | 27篇 |
1990年 | 20篇 |
1989年 | 25篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有9617条查询结果,搜索用时 562 毫秒
31.
The crystallization of poly(phenylene sulfide) (PPS) in a polymer–magnetic Nd—Fe—B powder suspension was studied. Isothermal crystallization behavior was analyzed by way of differential scanning calorimetry, and the kinetics were described via the Avrami equation. The Avrami parameters and the crystallization times were strongly affected by both the particle size and the presence of a coupling agent coated on the filler particles. The small Nd—Fe—B particles exhibited long induction and half‐times, whereas the large particles tended to have short crystallization times. Particles ranging from 38 to 150 μ appeared to have similar crystallization times and to have no significant change in the value of Avrami index with melt crystallization temperature. As a result of these analyses, the dynamic mechanical properties were determined to correlate the fundamental polymer crystallization characteristics and the physical properties of the PPS binder. The enhancement of the wetting of the filler to the binder was promoted through the coupling agent, as confirmed by dynamic mechanical testing performed on the samples. The storage modulus typically decreased because of the presence of the uncoated small particles. Conversely, the loss modulus was enhanced because of the presence of the coated small particles in the PPS binder. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1091–1102, 2002 相似文献
32.
A practical approach to develop a more realistic fault-tree model with a consideration of various conditions endured by a human operator is proposed. In safety-critical systems, the generation failure of an actuation signal is caused by the concurrent failures of the automated systems and an operator action. These two sources of safety signals are complicatedly correlated. The failures of sensors or automated systems will cause a lack of necessary information for a human operator and result in error-forcing contexts such as the loss of corresponding alarms and indications. It is well known that the error-forcing contexts largely affect the operator's performance. An automated system which consists of multiple processing channels and complex components is also affected by the availability of the sensors. This paper proposes a condition-based human reliability assessment (CBHRA) method in order to address these complicated conditions in a practical way. We apply the CBHRA method to the manual actuation of the safety features such as a reactor trip and auxiliary feedwater actuation in Korean Standard Nuclear Power Plants. Even the human error probability of each given condition is simply assumed, the application results prove that the CBHRA effectively accommodates the complicated error-forcing contexts into the fault trees. 相似文献
33.
Paulo S. André António L. Teixeira Armando N. Pinto Lara P. Pellegrino Berta B. Neto José F. Rocha Joäo L. Pinto Paulo N. Monteiro 《ETRI Journal》2006,28(2):257-259
In this letter, we will evaluate the performance degradation of a 40 km high‐speed (40 Gb/s) optical system, induced by optical fiber variations of the chromatic dispersion induced by temperature changes. The chromatic dispersion temperature sensitivity will be estimated based on the signal quality parameters. 相似文献
34.
Public participation is essential in each step of the nuclear-related decision-making process. Recently, the electronic systems using the Internet have become quite popular, and have emerged as a good medium for communicating with the public. In this study, a comprehensive utilization of electronic public participation was used to analyze public opinion on a given nuclear-related decision-making process. The degree of deliberation and meditation of the public participating in an electronic poll survey was evaluated, and the decision-making factors representing the personal characteristics of the poll respondents such as age, income, education, residence, degree of knowledge and concern were carefully incorporated when preparing the poll-survey questionnaire for its evaluation. Fuzzy analysis was used to assess and aggregate the responses to each decision-making factor. As a case study, this procedure was used to analyzing public opinion on the location of a low-level radioactive waste disposal facility on the campus of Seoul National University. The results show that there is a tendency of respondents who are on the negative side of the argument to be more deliberate and meditative in their decision-making process than those on the positive side. Knowledge and residence were found to be important decision-making factors. 相似文献
35.
36.
37.
This paper proposes a new LDMOSFET structure with a trenched sinker for high‐power RF amplifiers. Using a low‐temperature, deep‐trench technology, we succeeded in drastically shrinking the sinker area to one‐third the size of the conventional diffusion‐type structure. The RF performance of the proposed device with a channel width of 5 mm showed a small signal gain of 16.5 dB and a maximum peak power of 32 dBm with a power‐added efficiency of 25% at 2 GHz. Furthermore, the trench sinker, which was applied to the guard ring to suppress coupling between inductors, showed an excellent blocking performance below ?40 dB at a frequency of up to 20 GHz. These results confirm that the proposed trenched sinker should be an effective technology both as a compact sinker for RF power devices and as a guard ring against coupling. 相似文献
38.
We propose an efficient scheme for camera motion characterization in MPEG‐compressed video. The proposed scheme detects six types of basic camera motions through threshold‐based qualitative interpretation, in which fixed thresholds are applied to motion model parameters estimated from MPEG motion vectors (MVs). The efficiency and robustness of the scheme are validated by the experiment with real compressed video sequences. 相似文献
39.
Munhyoung Cho Chong Hyun Lee Soohong Kim Joohwan Chun 《AEUE-International Journal of Electronics and Communications》2004,58(4):299-301
In this paper, we propose a new robust code division multiple access (CDMA) receiver of which weight vector is obtained by projecting the effective spatio-temporal signature waveform onto the signal subspace of the data covariance matrix. We verified our proposed algorithm by the field measured data obtained with a custom-built wideband CDMA test-bed. It will be shown that the proposed algorithm is robust to the signal mismatch. 相似文献
40.