全文获取类型
收费全文 | 723篇 |
免费 | 9篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 17篇 |
综合类 | 6篇 |
化学工业 | 121篇 |
金属工艺 | 22篇 |
机械仪表 | 29篇 |
建筑科学 | 17篇 |
矿业工程 | 1篇 |
能源动力 | 46篇 |
轻工业 | 29篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
武器工业 | 1篇 |
无线电 | 163篇 |
一般工业技术 | 137篇 |
冶金工业 | 56篇 |
原子能技术 | 3篇 |
自动化技术 | 87篇 |
出版年
2024年 | 1篇 |
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 17篇 |
2013年 | 60篇 |
2012年 | 25篇 |
2011年 | 28篇 |
2010年 | 29篇 |
2009年 | 34篇 |
2008年 | 38篇 |
2007年 | 27篇 |
2006年 | 22篇 |
2005年 | 20篇 |
2004年 | 26篇 |
2003年 | 33篇 |
2002年 | 22篇 |
2001年 | 30篇 |
2000年 | 16篇 |
1999年 | 25篇 |
1998年 | 27篇 |
1997年 | 21篇 |
1996年 | 29篇 |
1995年 | 14篇 |
1994年 | 16篇 |
1993年 | 26篇 |
1992年 | 10篇 |
1991年 | 18篇 |
1990年 | 16篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有739条查询结果,搜索用时 15 毫秒
71.
刘重轩 《纺织高校基础科学学报》1997,10(1):42-45
箱式组合变电站箱内温的特点跟负载特性及箱壳的散热结构有关,而变电站内的电力变压器的负载率又跟箱内温升及箱壳的散热等级有关,本文给出了变压器负载率的计算公式和参考值。 相似文献
72.
Sivertsen K.N. Liou A.E.-L. Emami-Forooshani A. Michelson D.G. 《Wireless Communications, IEEE Transactions on》2009,8(8):3921-3925
We show by simulation that when the fading signals observed on orthogonally polarized diversity branches follow Ricean statistics, the distribution of polarization states on the Poincar′e sphere is well-approximated by a Fisher distribution. Further, we show that the Fisher concentration parameter is: (1) completely determined by the corresponding Ricean Kfactors and the cross-correlation coefficient between the diversity branches, both of which can be estimated from simple measurements of received power vs. time, and (2) a good indicator of the level of cross-polar discrimination (XPD) on the channel. The insights gained are potentially useful to those engaged in the development and validation of schemes that use either polarization re-use or polarized MIMO. 相似文献
73.
Dr. Hsueh‐Yun Lee Dr. Chia‐Ron Yang Dr. Mei‐Jung Lai Han‐Li Huang Yi‐Ling Hsieh Yi‐Min Liu Dr. Teng‐Kuang Yeh Yu‐Hsuan Li Samir Mehndiratta Dr. Che‐Ming Teng Dr. Jing‐Ping Liou 《Chembiochem : a European journal of chemical biology》2013,14(10):1248-1254
A series of 1‐arylsulfonyl‐5‐(N‐hydroxyacrylamide)indolines ( 7 – 15 ) has been developed; the compounds exhibited potent histone deacetylase (HDAC) inhibitory activities. Notably, almost all of this series exhibited better HDAC‐inhibitory and antiproliferative activities than 3‐(1‐benzenesulfonyl‐1H‐indol‐5‐yl)‐N‐hydroxyacrylamide ( 6 ), as reported in a previous study. Among these compounds, 3‐[1‐(4‐methoxybenzenesulfonyl)‐2,3‐dihydro‐1H‐indol‐5‐yl]‐N‐hydroxyacrylamide ( 9 ) showed a two‐ to tenfold increase in activity compared to SAHA ( 1 ) in the suppression of lipopolysaccharide‐induced cytokine production. Compound 9 also caused a marked reduction in carrageenan‐induced acute inflammation in a rat model. Taken together, these data indicated that 1‐arylsulfonyl‐5‐(N‐hydroxyacrylamide)indolines HDAC inhibitors exhibit potent anti‐inflammatory activity. 相似文献
74.
F. J. García Snchez A. Ortiz-Conde J. A. Salcedo J. Muci M. Estrada A. Cerdeira J. J. Liou Y. Yue 《Microelectronics Reliability》2000,40(6)
Our recently proposed method to extract the bulk-charge effect parameter in MOSFETs is scrutinized by studying SOI devices, a-Si:H TFTs and short- as well as long-channel bulk MOSFETs. The method requires measuring the drain current as a function of gate voltage at two small values of drain voltage chosen in the linear region of operation. 相似文献
75.
Various writing assistance tools have been developed through efforts in the areas of natural language processing with different degrees of success of curriculum integration depending on their functional rigor and pedagogical designs. In this paper, we developed a system, WriteAhead, that provides six types of suggestions when non‐native graduate students of English from different disciplines are composing journal abstracts, and assessed its effectiveness. The method involved automatically building domain‐specific corpora of abstracts from the Web via domain names and related keywords as query expansions, and automatically extracting vocabulary and n‐grams from the corpora in order to offer writing suggestions. At runtime, learners' input in the writing area of the system actively triggered a set of corresponding writing suggestions. This abstract writing assistant system facilitates interactions between learners and the system for writing abstracts in an effective and contextualized way, by providing suggestions such as collocations or transitional words. For assessment of WriteAhead, we compared the writing performance of two groups of students with or without using the system, and adopted student perception data. Findings show that the experiment group wrote better, and most students were satisfied with the system concerning most suggestion types, as they can effectively compose quality abstracts through provided language supports from WriteAhead. 相似文献
76.
Abstract A solution of the extended Graetz problem with prescribed wall heat flux and viscous dissipation in a semi‐infinite axial region of a tube is obtained by functional analytic methods. The energy equation is split into a set of partial differential equations to obtain a self‐adjoint formulism. Then, an algebraic characteristic equation of the eigenvalue problem for an arbitrary velocity profile is obtained by an approximation method in L 2[0, 1]. In addition, a backward recursive formula for calculating the expansion coefficients of the solution is developed. 相似文献
77.
Vinson J.E. Liou J.J. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2000,88(12):1878-1902
Electrostatic discharges (ESDs) are everywhere-in our homes and businesses. Even the manufacturers of the electronics experience ESD failures in their factories. Electronic devices are sensitive to ESD. ESD results in failure of our computers, calculators, and car phones. There are ways to protect these sensitive components. This paper looks at ESD protection from a two-pronged approach: reducing the likelihood of having an ESD event and improving the robustness of the devices themselves. The first approach focuses on reducing the amount of charge that is developed and controlling the redistribution of any charges that are developed The second approach reviews ways to improve the circuit robustness by improving individual circuit elements and by adding additional elements for charge flow control and voltage clamping 相似文献
78.
Jih-Wei Liou Bi-Shiou Chiou 《Journal of Materials Science: Materials in Electronics》2000,11(8):645-651
The effect of direct-current (d.c.) biasing on the dielectric properties of Ba0.65Sr0.35TiO3 (BST) with various grain sizes (0.87 μm to 5.43 μm) have been studied in the paraelectric state. The leakage current of BST samples is proportional to the biasing field. Specimens with larger grains exhibit higher leakage current under biasing. The bias equation used in the literature to predict the d.c. field dependence of permittivity is modified by introducing a bias exponent parameter β. This modified bias equation gives a better fit to the experimental results both in this study and in the literature. Similar trends of α (representing the distribution of relaxation times), β, and the variance of lattice distortion with grain sizes suggests that β is a material parameter. It is concluded that the temperature dependence, the frequency response and d.c. field effect for the dielectric characteristics of Ba0.65Sr0.35TiO3 are all suppressed by the transition broadening. 相似文献
79.
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
80.
Liou K.-Y. Koren U. Burrows E.C. Oron M. Miller B.I. Young M. Raybon G. Burrus C.A. 《Photonics Technology Letters, IEEE》1990,2(12):878-880
Monolithic integration of a monitoring detector with an optical amplifier simplifies the use of an amplifier in lightwave systems. The structure and performance are described of a monolithically integrated semiconductor optical amplifier with low-loss Y -branching waveguides and a monitoring p-i-n detector. The photocurrent of the integrated detector can be used as a single control parameter for amplifier output leveling, gain optimization, and in situ monitoring of facet antireflective coatings 相似文献