全文获取类型
收费全文 | 2345篇 |
免费 | 87篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 774篇 |
金属工艺 | 36篇 |
机械仪表 | 46篇 |
建筑科学 | 42篇 |
矿业工程 | 2篇 |
能源动力 | 116篇 |
轻工业 | 205篇 |
水利工程 | 16篇 |
石油天然气 | 5篇 |
无线电 | 217篇 |
一般工业技术 | 440篇 |
冶金工业 | 133篇 |
原子能技术 | 19篇 |
自动化技术 | 378篇 |
出版年
2024年 | 3篇 |
2023年 | 32篇 |
2022年 | 91篇 |
2021年 | 103篇 |
2020年 | 83篇 |
2019年 | 96篇 |
2018年 | 102篇 |
2017年 | 89篇 |
2016年 | 73篇 |
2015年 | 50篇 |
2014年 | 105篇 |
2013年 | 334篇 |
2012年 | 105篇 |
2011年 | 99篇 |
2010年 | 94篇 |
2009年 | 87篇 |
2008年 | 88篇 |
2007年 | 73篇 |
2006年 | 75篇 |
2005年 | 52篇 |
2004年 | 33篇 |
2003年 | 35篇 |
2002年 | 28篇 |
2001年 | 24篇 |
2000年 | 23篇 |
1999年 | 29篇 |
1998年 | 57篇 |
1997年 | 26篇 |
1996年 | 33篇 |
1995年 | 22篇 |
1994年 | 33篇 |
1993年 | 20篇 |
1992年 | 22篇 |
1991年 | 13篇 |
1990年 | 20篇 |
1989年 | 25篇 |
1988年 | 19篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 19篇 |
1982年 | 15篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1977年 | 3篇 |
1976年 | 11篇 |
1975年 | 4篇 |
排序方式: 共有2443条查询结果,搜索用时 15 毫秒
1.
Effects of DEM Source,Spatial Resolution and Drainage Area Threshold Values on Hydrological Modeling
Water Resources Management - Automated computation of hydrological and morphometric parameters of any watershed are not only depended on Digital Elevation Model (DEM) resolution but also affected... 相似文献
2.
3.
4.
We report on the use of pulsed plasma-enhanced chemical vapor deposition (P-PECVD) technique and show that “state-of-the-art” amorphous silicon (a-Si:H) materials and solar cells can be produced at a deposition rate of up to 15 Å/s using a modulation frequency in the range 1–100 kHz. The approach has also been developed to deposit materials and devices onto large area, 30 cm×40 cm, substrates with thickness uniformity (<5%), and gas utilization rate (>25%). We have developed a new “hot wire” chemical vapor deposition (HWCVD) method and report that our new filament material, graphite, has so far shown no appreciable degradation even after deposition of 500 μm of amorphous silicon. We report that this technique can produce “state-of-the-art” a-Si:H and that a solar cell of p/i/n configuration exhibited an initial efficiency approaching 9%. The use of microcrystalline silicon (μc-Si) materials to produce low-cost stable solar cells is gaining considerable attention. We show that both of these techniques can produce thin film μc-Si, dependent on process conditions, with 1 1 1 and/or 2 2 0 orientations and with a grain size of approx. 500 A. Inclusion of these types of materials into a solar cell configuration will be discussed. 相似文献
5.
Arun K. Nanda Honda Shing Ten-Hwan Tzen Lionel M. Ni 《Journal of Parallel and Distributed Computing》1991,12(4)
A standard metric conventionally employed to compare the performance of different multiprocessor systems is speedup. Although providing a measure of the improvement in execution speed achievable on a system, this metric does not yield any insight into the factors responsible for limiting the potential improvement in speed. This paper studies the performance degradation in shared-memory multiprocessors as a result of contention for shared-memory resources. A replicate workload framework with a flexible mechanism for workload specification is proposed for measuring performance. Two normalized performance metrics—efficiency and overhead factor—are introduced to quantify the factors limiting performance and facilitate comparison across architectures. Finally, the proposed model is employed to measure and compare the performance of three contemporary shared-memory systems, with special emphasis on the newly released BBN Butterfly-II (TC2000), currently undergoing Beta test. 相似文献
6.
We investigated the effect of repeated cold stress (RCS) on the capsaicin-evoked release of glutamate from the primary afferent fibers of the rat, and compared this with the effect of inoculation of complete Freund's adjuvant (adjuvant inoculation). The release of glutamate was measured using a fluorometric on-line continuous monitoring system in which the immobilized glutamate dehydrogenase column was connected to an in vitro superfusion system. In the presence of 0.3 microM tetrodotoxin, the application of 1 microM capsaicin to spinal dorsal horn slices evoked glutamate release (18.6 +/- 1.2 pmol mg(-1) protein, n = 11). In rats subjected to RCS (RCS rats), the release of glutamate evoked by 1 microM capsaicin was markedly increased to 272% (n = 6, P < 0.05) of the value for the control group, although the basal release was not significantly altered (n = 6, P > 0.05). Adjuvant inoculation produced a significant increase in the basal and capsaicin (1 microM) evoked release of glutamate to 141 and 344% (n = 6, P < 0.05) of the value for the control group, respectively. The present results suggest that the facilitated release of glutamate from capsaicin-sensitive primary afferent terminals in the spinal dorsal horn is, at least in part, involved in the hyperalgesia of RCS rats as well as the complete Freund's adjuvant-induced hyperalgesia. 相似文献
7.
8.
9.
A method for evaluating the accuracy of a device model and its tendency toward convergence problems before implementing it as a SPICE primitive is presented. Two different GaAs MESFET models suitable for analyzing nonlinear analog and microwave circuits are implemented using generic SPICE primitives. It is shown that no modification to the SPICE program is required. Controlled sources are extensively used in implementing the models using this method 相似文献
10.
A dynamic rcsring dnim war built to study the effects of air temperature, moisture content and grain shape on fragility of the air dried kernels. For drying rares under 0.05 kglkg min. the fragility of kernels could br described empirically as a function of the three experimental parameters. 相似文献