全文获取类型
收费全文 | 1730篇 |
免费 | 76篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 42篇 |
综合类 | 5篇 |
化学工业 | 249篇 |
金属工艺 | 39篇 |
机械仪表 | 45篇 |
建筑科学 | 140篇 |
矿业工程 | 7篇 |
能源动力 | 98篇 |
轻工业 | 136篇 |
水利工程 | 16篇 |
石油天然气 | 6篇 |
无线电 | 197篇 |
一般工业技术 | 223篇 |
冶金工业 | 181篇 |
原子能技术 | 7篇 |
自动化技术 | 416篇 |
出版年
2023年 | 12篇 |
2022年 | 18篇 |
2021年 | 34篇 |
2020年 | 25篇 |
2019年 | 18篇 |
2018年 | 47篇 |
2017年 | 33篇 |
2016年 | 50篇 |
2015年 | 48篇 |
2014年 | 47篇 |
2013年 | 136篇 |
2012年 | 95篇 |
2011年 | 88篇 |
2010年 | 100篇 |
2009年 | 79篇 |
2008年 | 78篇 |
2007年 | 106篇 |
2006年 | 83篇 |
2005年 | 53篇 |
2004年 | 57篇 |
2003年 | 64篇 |
2002年 | 36篇 |
2001年 | 29篇 |
2000年 | 37篇 |
1999年 | 25篇 |
1998年 | 43篇 |
1997年 | 22篇 |
1996年 | 38篇 |
1995年 | 19篇 |
1994年 | 17篇 |
1993年 | 23篇 |
1992年 | 28篇 |
1991年 | 22篇 |
1990年 | 18篇 |
1989年 | 17篇 |
1988年 | 14篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 19篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1973年 | 7篇 |
1971年 | 3篇 |
排序方式: 共有1807条查询结果,搜索用时 15 毫秒
141.
142.
Nontexture Inpainting by Curvature-Driven Diffusions 总被引:4,自引:0,他引:4
Inpainting is an image interpolation problem, often referring to interpolations over large-scale missing domains. In this paper, guided by the connectivity principle of human visual perception, we introduce a nonlinear PDE inpainting model based upon curvature-driven diffusions for nontexture images. This third-order PDE model improves the second-order total variation inpainting model introduced earlier by Chan and Shen (SIAM J. Appl. Math., in press, 2001). Computational schemes and digital examples are given. 相似文献
143.
144.
145.
High crude oil prices, uncertainties about the consequences of climate change and the eventual decline of conventional oil production raise the issue of alternative fuels, such as non-conventional oil and biofuels. This paper describes a simple probabilistic model of the costs of non-conventional oil, including the role of learning-by-doing in driving down costs. This forward-looking analysis quantifies the effects of both learning and production constraints on the costs of supplying bitumen, which can then be upgraded into synthetic crude oil, a substitute to conventional oil. The results show large uncertainties in the future costs of supplying bitumen from Canadian oil sands deposits, with a 90% confidence interval of $7–12 in 2030, and $6–15 in 2060 (2005 US$). The influence of each parameter on the supply costs is examined, with the minimum supply cost, the learning rate (LR), and the depletion curve exponent having the largest influence. Over time, the influence of the LR on the supply costs decreases, while the influence of the depletion curve exponent increases. 相似文献
146.
A high-speed directional comparison relay based on an evaluation of the locally measured deviations of the voltage and the phase-shifted current from their prefault values is described. The operation of the relay depends on the power frequency components of the voltage and phase-shifted current deviation signals. The direction to a fault is determined by an amplitude comparator technique which compares a discriminant value with a positive or negative threshold. Simulation studies on a three-phase power system model show that the direction to a fault is determined within the first few milliseconds following the inception of a fault. Studies over a wide range of faults and source impedance angles show that the proposed amplitude comparator technique performs better than an analogous phase comparator technique 相似文献
147.
Prakash K.S. Malik O.P. Hope G.S. Hancock G.C. Wong K.K. 《Power Delivery, IEEE Transactions on》1990,5(4):1687-1694
A directional comparison digital protection scheme has been implemented with a 16-b single-board computer at each end of a physical model of a transmission line, with communication between the two ends. The protection algorithm makes use of the fundamental frequency components of the deviation signals of the voltage and phase-shifted current. Software routines have been developed for fault monitoring, directional determination, and the trip/block decision. Graphics features incorporated in the software are explained. Tests for various faults conducted on the physical model of a double-circuit transmission line show that the direction to a fault is determined in 3 to 7 ms. The blocking features of the relay are demonstrated 相似文献
148.
Cover Picture: Discovery of MK‐8970: An Acetal Carbonate Prodrug of Raltegravir with Enhanced Colonic Absorption (ChemMedChem 2/2015) 下载免费PDF全文
Dr. Abbas M. Walji Dr. Rosa I. Sanchez Dr. Sophie‐Dorothee Clas Dr. Rebecca Nofsinger Dr. Manuel de Lera Ruiz Dr. Jing Li Dr. Amrithraj Bennet Christopher John Dr. David Jonathan Bennett Dr. John M. Sanders Christina N. Di Marco Somang Hope Kim Dr. Jaume Balsells Scott S. Ceglia Dr. Qun Dang Kimberly Manser Becky Nissley Dr. John S. Wai Dr. Michael Hafey Junying Wang Gene Chessen Dr. Allen Templeton Dr. John Higgins Dr. Ronald Smith Dr. Yunhui Wu Dr. Jay Grobler Dr. Paul J. Coleman 《ChemMedChem》2015,10(2):213-213
149.
Hope Badawy Jér?me Brunellière Marina Veryaskina Guillaume Brotons Sophie Sablé Isabelle Lanneluc Kelly Lambert Pascal Marmey Amy Milsted Teresa Cutright Arnaud Nourry Jean-Luc Mouget Pamela Pasetto 《International journal of molecular sciences》2015,16(3):4392-4415
There has been an intense research effort in the last decades in the field of biofouling prevention as it concerns many aspects of everyday life and causes problems to devices, the environment, and human health. Many different antifouling and antimicrobial materials have been developed to struggle against bacteria and other micro- and macro-organism attachment to different surfaces. However the “miracle solution” has still to be found. The research presented here concerns the synthesis of bio-based polymeric materials and the biological tests that showed their antifouling and, at the same time, antibacterial activity. The raw material used for the coating synthesis was natural rubber. The polyisoprene chains were fragmented to obtain oligomers, which had reactive chemical groups at their chain ends, therefore they could be modified to insert polymerizable and biocidal groups. Films were obtained by radical photopolymerization of the natural rubber derived oligomers and their structure was altered, in order to understand the mechanism of attachment inhibition and to increase the efficiency of the anti-biofouling action. The adhesion of three species of pathogenic bacteria and six strains of marine bacteria was studied. The coatings were able to inhibit bacterial attachment by contact, as it was verified that no detectable leaching of toxic molecules occurred. 相似文献
150.
Tony Manzi 《Housing Studies》2010,25(1):5-19
This paper examines housing policies aimed at establishing mixed income communities. Based on stakeholder interviews and case study analysis in England and Scotland, the paper pays particular attention to the impact of interventions in housing management. The first part considers the policy context for mixed communities and considers the conceptual basis underlying contemporary housing management through discourses of culture and social control. The second part considers how this agenda has resulted in the adoption of intensive management strategies within mixed communities; illustrated in the development of allocation policies, initiatives designed to tackle anti-social behaviour, and proposals to develop sustainable communities. The main argument is that given that the concept of mixed communities is based on the premise of social housing failure, citizenship has been defined largely in response to private sector interests. This approach to management has been a contributory factor in the construction of social housing as a form of second-class citizenship. 相似文献