全文获取类型
收费全文 | 17079篇 |
免费 | 1233篇 |
国内免费 | 48篇 |
专业分类
电工技术 | 229篇 |
综合类 | 16篇 |
化学工业 | 3761篇 |
金属工艺 | 604篇 |
机械仪表 | 1237篇 |
建筑科学 | 318篇 |
矿业工程 | 3篇 |
能源动力 | 715篇 |
轻工业 | 1427篇 |
水利工程 | 95篇 |
石油天然气 | 19篇 |
无线电 | 3202篇 |
一般工业技术 | 3772篇 |
冶金工业 | 872篇 |
原子能技术 | 248篇 |
自动化技术 | 1842篇 |
出版年
2024年 | 9篇 |
2023年 | 199篇 |
2022年 | 221篇 |
2021年 | 569篇 |
2020年 | 385篇 |
2019年 | 458篇 |
2018年 | 517篇 |
2017年 | 596篇 |
2016年 | 658篇 |
2015年 | 569篇 |
2014年 | 787篇 |
2013年 | 1154篇 |
2012年 | 1200篇 |
2011年 | 1467篇 |
2010年 | 989篇 |
2009年 | 1063篇 |
2008年 | 940篇 |
2007年 | 760篇 |
2006年 | 653篇 |
2005年 | 585篇 |
2004年 | 535篇 |
2003年 | 513篇 |
2002年 | 507篇 |
2001年 | 408篇 |
2000年 | 360篇 |
1999年 | 329篇 |
1998年 | 431篇 |
1997年 | 281篇 |
1996年 | 227篇 |
1995年 | 163篇 |
1994年 | 145篇 |
1993年 | 107篇 |
1992年 | 85篇 |
1991年 | 75篇 |
1990年 | 65篇 |
1989年 | 80篇 |
1988年 | 42篇 |
1987年 | 52篇 |
1986年 | 34篇 |
1985年 | 40篇 |
1984年 | 27篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
A neural network-based power system stabilizer (neuro-PSS) is designed for a generator connected to a multi-machine power system utilizing the nonlinear power flow dynamics. The use of power flow dynamics provides a PSS for a wide range of operation with reduced size neural networks. The neuro-PSS consists of two neural networks: neuro-identifier and neuro-controller. The low-frequency oscillation is modeled by the neuro-identifier using the power flow dynamics, then a generalized backpropagation-through-time (GBTT) algorithm is developed to train the neuro-controller. The simulation results show that the neuro-PSS designed in this paper performs well with good damping in a wide operation range compared with the conventional PSS 相似文献
82.
83.
84.
Jae-Hee Han Su Hong Lee A.S. Berdinsky Yong Weon Kim Ji-Beom Yoo Chong-Yun Park Jin Ju Choi Taewon Jung In Taek Han Jong Min Kim 《Diamond and Related Materials》2005,14(11-12):1891
In this report, the FE characteristics of carbon nanotubes (CNTs) treated using both thermal annealing and mechanical coatings on the as-grown CNTs systematically studied. It was found that in the high temperature annealed samples, CNTs were attacked at its root during annealing due to a small amount of oxygen, and were pulled out of the substrate in places after FE measurements because of the contact resistance. However, for the mechanically coated samples both with spin on glass (SOG) and polymethyl methacrylate (PMMA), CNTs were found to be nearly intact after FE measurements and showed reliable FE characteristics over repeatable voltage scan. The reliability of CNTs during FE could be owing to the strong adhesion of CNTs to the substrate both by SOG and PMMA coatings. 相似文献
85.
Hyun-Ho Choi Sang-Yoon Lee Il-Yoon Choi Hyo-Nam Cho Sankaran Mahadevan 《Reliability Engineering & System Safety》2006,91(6):674-688
Until now, in many forensic reports, the failure cause assessments are usually carried out by a deterministic approach so far. However, it may be possible for the forensic investigation to lead to unreasonable results far from the real collapse scenario, because the deterministic approach does not systematically take into account any information on the uncertainties involved in the failures of structures.Reliability-based failure cause assessment (reliability-based forensic engineering) methodology is developed which can incorporate the uncertainties involved in structural failures and structures, and to apply them to the collapsed bridge in order to identify the most critical failure scenario and find the cause that triggered the bridge collapse. Moreover, to save the time and cost of evaluation, an algorithm of automated event tree analysis (ETA) is proposed and possible to automatically calculate the failure probabilities of the failure events and the occurrence probabilities of failure scenarios. Also, for reliability analysis, uncertainties are estimated more reasonably by using the Bayesian approach based on the experimental laboratory testing data in the forensic report. For the applicability, the proposed approach is applied to the Hang-ju Grand Bridge, which collapsed during construction, and compared with deterministic approach. 相似文献
86.
For multi-step heterogeneous consecutive reactions affected entirely by interphase diffusion under isothermal condition, the
equations for the effectiveness factors, the surface concentrations and the point yields were derived in terms of the Damkoehler
numbers or the measurables from the mass balances set up on the assumption that the mass-transfer rate balances the surface-reaction
rate at steady state.
From the analyses of the equations derived, the effectiveness factors for the intermediate steps and the surface concentrations
of intermediates were understood to be enhanced by the measurables inclusive of the concentrations and the mass-transfer coefficients.
Then the effect of the concentrations was concluded to be most significant. The effects of these measurables to the effectiveness
factors and the surface concentrations were qualitatively discussed for simple consecutive reactions and also for additive
consecutive reactions. Especially, as for two-step additive consecutive reactions, the effects of measurables η Da and the
concentrations to the effectiveness factors were examined with graphical presentations.
Finally, the brief discussion of the dependency of the Damkoehler number upon reaction time and the effect of the Renolds
number and diffusivity to the extent of the mass-transfer resistance were presented. 相似文献
87.
A compact dipole antenna for the terrestrial digital multimedia broadcasting (TDMB) application is presented. The length of the antenna is about 0.06λ at the TDMB resonance frequency of 190 MHz. Miniaturization of the antenna is achieved by using meander structures and lumped elements. The proposed antenna has two resonance frequencies and covers the TDMB band from 174 MHz to 216 MHz in Korea. The antenna has good impedance bandwidth and radiation characteristics for the TDMB. The experimental results of the designed dipole antenna are presented and analyzed. 相似文献
88.
Characterisation of a BioFET for detection of albumin in a mixture of human urine is presented. To avoid electrolyte effect of the urine, it was measured in PBS (phosphate buffer saline) at a fixed pH after albumin binding. The drain current was modulated by the albumin bound to the anti-albumin immobilised on the gate surface of the BioFET. The current variation ratio was likely to be proportional to the concentration of the albumin in the range 50-250 mg/1. The results show the feasibility of the BioFET as a urinary albumin sensor. 相似文献
89.
Joon C. Park Author Vitae Author Vitae 《Computer aided design》2003,35(9):807-812
Presented in this paper is a topology reconstruction algorithm from a set of unorganized trimmed surfaces. Error-prone small geometric elements are handled to give proper topological information. It gives complete topology to topologically complete models, and it is also tolerant to incomplete models. The proposed algorithm is vertex-based in that clues for topological information are searched from the set of vertices first, not from that of edges. 相似文献
90.
Effects of austenitizing treatment temperatures on aqueous corrosion properties of martensitic stainless steels were investigated by electrochemical tests (potentiodynamic test, potentiostatic test and electrochemical impedance spectroscopy), and surface analyses (optical microscopy and XRD). The results of potentiodynamic test revealed that the breakdown potential increased with the increased austenitizing temperature, indicating increased relative resistance to initiation of localized corrosion. EIS measurements showed that MSS3 (1030 °C) exhibits larger polarization resistance value than MSS1 (970 °C) and MSS2 (1000 °C) at passive and breakdown states. This was caused by decreasing the amount of Cr-rich M23C6 carbide which acts as preferential sites for pitting corrosion. 相似文献