全文获取类型
收费全文 | 1191篇 |
免费 | 31篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 21篇 |
综合类 | 2篇 |
化学工业 | 289篇 |
金属工艺 | 43篇 |
机械仪表 | 24篇 |
建筑科学 | 43篇 |
能源动力 | 47篇 |
轻工业 | 70篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 147篇 |
一般工业技术 | 256篇 |
冶金工业 | 124篇 |
原子能技术 | 9篇 |
自动化技术 | 142篇 |
出版年
2023年 | 8篇 |
2022年 | 22篇 |
2021年 | 33篇 |
2020年 | 31篇 |
2019年 | 23篇 |
2018年 | 35篇 |
2017年 | 26篇 |
2016年 | 31篇 |
2015年 | 21篇 |
2014年 | 27篇 |
2013年 | 78篇 |
2012年 | 47篇 |
2011年 | 54篇 |
2010年 | 33篇 |
2009年 | 47篇 |
2008年 | 57篇 |
2007年 | 38篇 |
2006年 | 36篇 |
2005年 | 41篇 |
2004年 | 34篇 |
2003年 | 20篇 |
2002年 | 23篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1998年 | 30篇 |
1997年 | 31篇 |
1996年 | 20篇 |
1995年 | 22篇 |
1994年 | 15篇 |
1993年 | 16篇 |
1992年 | 17篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 16篇 |
1983年 | 20篇 |
1982年 | 15篇 |
1980年 | 12篇 |
1979年 | 16篇 |
1978年 | 10篇 |
1976年 | 21篇 |
1975年 | 13篇 |
1974年 | 8篇 |
1973年 | 7篇 |
1971年 | 9篇 |
排序方式: 共有1225条查询结果,搜索用时 15 毫秒
101.
102.
This paper discusses the iterative provision of modelling insights on long-term decarbonisation scenarios for UK energy policy makers. A multi-year model construction process of the UK MARKAL-Macro-hybrid energy-economic model, and four subsequent major policy analyses illustrates the scope of this interaction. The initial set of modelling runs focused on the technical feasibility of long-term 60% carbon dioxide (CO2) reduction scenarios, the role of key technologies, and the underlying uncertainties. Furthermore subsequent modelling studies were aimed to generate insights on more stringent targets, and on issues and uncertainties that may make targets harder to achieve. Hence, this paper analyses the large number of long-term UK CO2 reduction scenarios through a clustering approach on target stringency and barriers to implementation. Robust findings and key uncertainties are highlighted, including the critical role of the power sector, trade-offs between resources, sectors, key energy technologies and behavioural responses, and the increasing level and spread of CO2 marginal prices and GDP impacts. The relevance and use of modelling insights to the UK energy policy process is shown in the continuation of the energy modelling–policy interface. This constitutes both ongoing model development, and nuanced scenario analysis designed to further explore key uncertainties in evolving policy issues. 相似文献
103.
Sarkar Santonu Ramachandran Shubha Kumar G. Sathish Iyengar Madhu K. Rangarajan K. Sivagnanam Saravanan 《Software, IEEE》2009,26(2):28-35
Large software systems, developed over several years, are the backbone of industries such as banking, retail, transportation, and telecommunications. With multiple bug fixes and feature enhancements, these systems gradually deviate from the intended architecture and deteriorate into unmanageable monoliths. This article presents a case study of a banking application besot with such problems and the modularization approach that the company adopted as a solution. It also highlights benefits unearthed as a result of this reengineering exercise. 相似文献
104.
105.
106.
H. B. Sunkara B. G. Penn D. O. Frazier N. Ramachandran 《Journal of Materials Science》1998,33(4):887-894
The photoinitiated bulk polymerization process, which has been used recently in the manufacture of solid optical diffraction filters, is examined to understand the dynamics of both the crystalline colloidal arrays (CCA) and the host monomer species. Our analysis indicates that volume shrinkage of the monomer, changes in the dielectric properties of the monomer, and inhomogeneities of polymerization reaction rate across the dispersion during the polymerization process, are the major contributors for observed lattice compression and lattice disorder of the CCA of silica spheres in polymerized acrylic/methacrylic ester films. The effect of orientation of photocell with respect to the radiation source on Bragg diffraction of CCA indicated the presence of convective stirring in the thin fluid system during the photopolymerization that deleteriously affects the periodic array structures. To devise reproducible and more efficient optical filters, experimental methods to minimize or eliminate convective instabilities in monomeric dispersions during polymerization are suggested. © 1998 Chapman & Hall 相似文献
107.
Non-accidental head injury, be it shaking, impact(s) or a combination of the two, is characterised by subdural and/or subarachnoid haemorrhages with retinal haemorrhages, but minimal or absent external cranio-facial trauma. The classical assault scenario depicts the infant being gripped around the head, face, chest and abdomen and shaken or being gripped by a limb and swung. This gripping might be expected to leave physical evidence in the form of bruising. A study was undertaken to establish the prevalence, distribution and pathological association of external bruising in 24 cases of fatal non-accidental head injury in children. At autopsy, 17 cases had new external bruises, 15 old external bruises and 13, a combination of both. However, seven (29%) cases showed no fresh external bruising and five (21%) showed no external bruising at all. Thus, external bruising may be absent in children with fatal intracranial injury. The face was shown to be the commonest site of bruising followed by the forehead and buttocks. Limb, chest and abdominal bruising were found to be uncommon. Retinal haemorrhages were confirmed in 23 (96%) cases. It is hypothesised that bruising, when present, may be a result of abuse in the form of punches and slaps rather than due to gripping during the assault. We discuss why gripping does not necessarily result in external bruising. 相似文献
108.
Electrochemical copolymerization of diphenylamine (DPA) with o‐chloroaniline (OCA) was performed in aqueous 4M sulfuric acid using the pulse potentiostatic method (PPSM). By employing the tunable parameters in PPSM, polymeric films were deposited under different conditions. Cyclic voltammetry was used for evaluating the characteristics of the deposited polymeric films. A suitable growth equation for the deposition of polymer, relating the charge associated for the film deposition and the pulse parameters in PPSM, was deduced. Various surface parameters are evaluated. The formation of copolymer during PPSM deposition was revealed through critical analysis of the results. The characteristic differences between the individual homopolymers, poly(diphenylamine) and poly(o‐chloroaniline) and the copolymer, poly(diphenylamine‐co‐o‐chloroaniline), were brought out. The copolymer was also synthesized through a chemical method and characterized through infrared and ultraviolet‐visible spectroscopic analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 389–397, 2003 相似文献
109.
Raj R. K. Joseph M. Aanandan C. K. Vasudevan K. Mohanan P. 《Antennas and Propagation, IEEE Transactions on》2006,54(12):3755-3762
A novel compact microstrip fed dual-band coplanar antenna for wireless local area network is presented. The antenna comprises of a rectangular center strip and two lateral strips printed on a dielectric substrate and excited using a 50 Omega microstrip transmission line. The antenna generates two separate resonant modes to cover 2.4/5.2/5.8 GHz WLAN bands. Lower resonant mode of the antenna has an impedance bandwidth (2:1 VSWR) of 330 MHz (2190-2520 MHz), which easily covers the required bandwidth of the 2.4 GHz WLAN, and the upper resonant mode has a bandwidth of 1.23 GHz (4849-6070 MHz), covering 5.2/5.8 GHz WLAN bands. The proposed antenna occupy an area of 217 mm2 when printed on FR4 substrate (epsivr=4.7). A rigorous experimental study has been conducted to confirm the characteristics of the antenna. Design equations for the proposed antenna are also developed 相似文献
110.
P. B. S. N. V. Prasad R. Vasudevan S. K. Seshadri 《Journal of Materials Science Letters》1992,11(21):1424-1425