全文获取类型
收费全文 | 636篇 |
免费 | 7篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 66篇 |
金属工艺 | 7篇 |
机械仪表 | 20篇 |
建筑科学 | 6篇 |
能源动力 | 36篇 |
轻工业 | 33篇 |
水利工程 | 1篇 |
石油天然气 | 9篇 |
无线电 | 182篇 |
一般工业技术 | 82篇 |
冶金工业 | 70篇 |
原子能技术 | 3篇 |
自动化技术 | 122篇 |
出版年
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 64篇 |
2012年 | 20篇 |
2011年 | 17篇 |
2010年 | 22篇 |
2009年 | 19篇 |
2008年 | 32篇 |
2007年 | 38篇 |
2006年 | 28篇 |
2005年 | 27篇 |
2004年 | 15篇 |
2003年 | 23篇 |
2002年 | 27篇 |
2001年 | 22篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 39篇 |
1997年 | 22篇 |
1996年 | 22篇 |
1995年 | 9篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 21篇 |
1991年 | 14篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有645条查询结果,搜索用时 15 毫秒
51.
ABSTRACT Structure, Interaction, and phase transition of a vacuum residue fractions In various apolar solvents were Investigated, using viscosity measurements and small angle neutron scattering. Both light and heavy ended fractions form colloidal particles of spherical shape with average sizes of -40 and -60 A respectively. The size distributions follow a Schultz distribution function approximately. Rheological studies of these fractions indicated significant particle solvation. The solvation mechanism is through association of the solvent molecules with individual VR colloids, instead of through solvent entrapment between agglomerated colloids. The viscosity, as a function of temperature, suggested a glass-like transition at approximately 254?K for the heavy ended fraction at 0.5 volume fraction. The small angle neutron scattering measurements confirmed the colloidal structure determined from rheological study. It also provided the information about the total colloids/solvent Interfacial area, from which we found that VR colloids have a rough surface 相似文献
52.
The long-term current instability of AlGaAs/GaAs heterojunction bipolar transistor (HBT) is studied, and the physical mechanism contributing to such a behavior is investigated. Based on this, a model capable of predicting the HBT long-term current drift and mean time to failure (MTTF) is developed. In addition, such a model is implemented into SPICE circuit simulator, thus allowing the simulation of HBT circuits subjected to an electrical and thermal stress condition. 相似文献
53.
Sheu J.-P. Han-Lih Wang Chi-He Chang Yu-Chee Tseng 《Broadcasting, IEEE Transactions on》2004,50(2):120-125
Broadcasting is a prospective approach to support near video-on-demand services with light communication overhead. By letting clients share channels, such approaches involve partitioning a video into segments and repeatedly broadcasting these segments in multiple channels. An early paper proposed a broadcasting scheme called RFS (recursive frequency splitting), which can significantly reduce clients' waiting time. While efficient, RFS suffers from a high computational complexity of O(nlogn), where n is the number of segments of the video, which is typically very large. This paper proposes an efficient segmentation scheme, which can significantly reduce the computational overhead by slightly sacrificing the number of segments that can be arranged as compared to RFS. 相似文献
54.
Nitride-Based ultraviolet metal-semiconductor-metal photodetectors with a low-temperature GaN layer 总被引:1,自引:0,他引:1
J. K. Sheu C. J. Kao M. L. Lee W. C. Lai L. S. Yeh G. C. Chi S. J. Chang Y. K. Su J. M. Tsai 《Journal of Electronic Materials》2003,32(5):400-402
The GaN metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors with a low-temperature (LT)-GaN layer have been demonstrated.
It was found that we could achieve a two orders of magnitude smaller, photodetector-dark current by introducing a LT-GaN layer,
which could be attributed to the larger Schottky-barrier height between the Ni/Au metal contact and the LT-GaN layer. It was
also found that photodetectors with the LT-GaN layer could provide a larger photocurrent to dark-current contrast ratio and
a larger UV-to-visible rejection ratio. The maximum responsivity was found to be 3.3 A/W and 0.13 A/W when the photodetector
with a LT-GaN layer was biased at 5 V and 1 V, respectively. 相似文献
55.
Richard H. Tsai Bing J. Sheu Theodore W. Berger 《Analog Integrated Circuits and Signal Processing》1998,15(2):201-213
The hippocampal region of the brain system can be analyzed with the nonlinear system modeling approach. The input-output relationship of the neural units is best represented by the kernel functions of different complexities. The modeling expression of the first and second order kernels are computed in analog current-mode instead of digital data processing in order to fully explore massively parallel processing capability of the neural networks. Two distinct methods are utilized: the table-look-up approach and the model-based approach. The former can achieve high accuracy but consumes large silicon area while the latter saves silicon area and maintains moderately high accuracy. Circuit-level simulation results and experimental data from two test structures are presented. 相似文献
56.
Meng-Lieh Sheu 《Analog Integrated Circuits and Signal Processing》2002,31(3):191-192
57.
Shey-Huei Sheu 《Microelectronics Reliability》1992,32(5)
A system is subject to shocks that arrive according to a nonhomogeneous Poisson process. The system is replaced at age T at a fixed cost c0. If the k-th shock arrives at time Sk<T, it is either a fatal shock with probability p(Sk) or a nonfatal shock with probability 1−p(Sk). The fatal shock causes the system total breakdown, and the system is replacd at a cost c∞. The nonfatal shock weakens the system and makes it more expensive to run. The aim of the paper is to find the optimal T which minimizes the long run expected cost per unit time of the policy. Various special cases are considered. 相似文献
58.
Ming-Hwa Sheu Su-Hon Lin Chichyang Chen Shyue-Wen Yang 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2004,51(3):152-155
In this paper, we present a new four-moduli set (2/sup n/-3,2/sup n/+1,2/sup n/-1,2/sup n/+3) and an efficient residue to binary (R/B) converter design. The merits of the proposed four-moduli set include 1) larger dynamic range; 2) higher degree of parallelism for conversion; 3) balanced bit-width for internal RNS arithmetic operations; and 4) flexible moduli set selection. According to the relation between the proposed moduli, the divide-and-conquer technique is used to design a two-level converter architecture which has lower hardware cost and shorter critical delay. For the R/B converter designed with 12-b (n=3), our architecture has about 47% saving in hardware cost and 40% saving in critical delay compared to the last work. 相似文献
59.
EY Sheu 《Canadian Metallurgical Quarterly》1992,45(4):2428-2438
60.
Bing-Joe Hwang Shao-Kang Hu Ching-Hsiang Chen Chun-Yu Chen Hwo-Shuenn Sheu 《Journal of power sources》2007
The structural changes of pristine and ZrO2-coated LiMn0.5Ni0.5O2 cathode materials were investigated by using in situ X-ray diffraction (XRD) during charging process. An obviously solid solution phase transition from a hexagonal structure (H1) to another hexagonal structure (H2) was observed during the charging process at a constant current of 0.3 mA in the potential range of 2.5–5.7 V. The second hexagonal structure has a shorter a-axis and a longer c-axis before the crystal collapse. Before the structure collapses the c-axis length increases to maximum and then significantly decreases to 14.1 Å. The c-axis length of the pristine and ZrO2-coated LiMn0.5Ni0.5O2 increases to the maximum at the charge capacity of 119.2 and 180.9 mAh g−1, respectively. It can be concluded that the ZrO2 coating can strongly stabilize the crystal structure of the LiMn0.5Ni0.5O2 compound from the comparison of the lattice parameter variations between the pristine and the ZrO2-coated LiMn0.5Ni0.5O2 compounds upon charge. The potential fluctuation resulting from the decomposition of electrolytes starts at the charge capacity of around 200 and 260 mAh g−1 for the pristine and ZrO2-coated LiMn0.5Ni0.5O2, respectively. It suggests that the ZrO2 coating layer can impede the reaction between the cathode material and electrolyte. 相似文献