全文获取类型
收费全文 | 1367篇 |
免费 | 72篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 15篇 |
综合类 | 1篇 |
化学工业 | 324篇 |
金属工艺 | 25篇 |
机械仪表 | 20篇 |
建筑科学 | 52篇 |
矿业工程 | 12篇 |
能源动力 | 47篇 |
轻工业 | 79篇 |
水利工程 | 9篇 |
石油天然气 | 12篇 |
无线电 | 105篇 |
一般工业技术 | 382篇 |
冶金工业 | 84篇 |
原子能技术 | 28篇 |
自动化技术 | 248篇 |
出版年
2024年 | 2篇 |
2023年 | 17篇 |
2022年 | 9篇 |
2021年 | 51篇 |
2020年 | 34篇 |
2019年 | 36篇 |
2018年 | 36篇 |
2017年 | 50篇 |
2016年 | 39篇 |
2015年 | 47篇 |
2014年 | 63篇 |
2013年 | 117篇 |
2012年 | 89篇 |
2011年 | 109篇 |
2010年 | 68篇 |
2009年 | 56篇 |
2008年 | 90篇 |
2007年 | 77篇 |
2006年 | 58篇 |
2005年 | 56篇 |
2004年 | 37篇 |
2003年 | 49篇 |
2002年 | 43篇 |
2001年 | 18篇 |
2000年 | 13篇 |
1999年 | 13篇 |
1998年 | 13篇 |
1997年 | 17篇 |
1996年 | 13篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 11篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1976年 | 3篇 |
1971年 | 5篇 |
1969年 | 2篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1443条查询结果,搜索用时 46 毫秒
101.
Boris Beizer 《Annals of Software Engineering》2000,10(1-4):293-310
The reliability notions that have worked so well for hardware do not work for software. It is not just reliability issues
that makes software engineering different than most traditional engineering disciplines, but fundamental, usually unrecognized
paradigms. Twelve assumptions that are rarely questioned in traditional engineering fields are explored and each is shown
not to hold in software engineering. These differences between software engineering and traditional engineering are often
at the core of misunderstandings between their practitioners.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
102.
Rainer Wesche Pierluigi Bruzzone Stephen March Claudio Marinucci Boris Stepanov Davide Uglietti 《Fusion Engineering and Design》2013,88(9-10):1495-1498
In the last few years, the critical current densities of long commercially available REBa2Cu3O7?x (RE-123, where RE represents Y or a rare earth element) coated conductors have reached values of 250 A/cm-width at 77 K and zero applied field. Even higher values of 600 A/cm-w (77 K, B = 0) have been demonstrated in shorter lengths. The attractive features of the use of these high-Tc superconductors (HTS) are operation temperatures above 20 K and/or magnetic fields higher than those envisaged for the ITER TF coils. Possible operation conditions for HTS fusion magnets have been studied taking into consideration the possible further improvements of RE-123 coated conductors. Investigations of stability and quench behavior indicate that stability is not a problem, whereas quench detection and protection need attention. Because of the high currents necessary for fusion magnets, many tapes need to be assembled into a transposed conductor. The qualification of HTS conductors for fusion magnets would require their test at magnetic fields of 11 T and currents well above 10 kA. The possibilities to test straight HTS conductor samples in SULTAN have been considered. For a test at 4.5 K, only the development of a low resistance joint between the HTS conductor under test and the NbTi transformer of SULTAN would be necessary. Tests up to 20 K would require that the HTS sample is connected with the NbTi transformer by a conduction-cooled HTS bus bar of large thermal resistance similar to the HTS module of a current lead. HTS conductor tests at temperatures around 50 K would be possible with modified cryogenics. 相似文献
103.
Larisa I. Privalova Boris A. Katsnelson Nadezhda V. Loginova Vladimir B. Gurvich Vladimir Y. Shur Yakov B. Beikin Marina P. Sutunkova Ilzira A. Minigalieva Ekaterina V. Shishkina Svetlana V. Pichugova Ludmila G. Tulakina Svetlana V. Beljayeva 《International journal of molecular sciences》2014,15(11):21538-21553
We used stable water suspensions of copper oxide particles with mean diameter 20 nm and of particles containing copper oxide and element copper with mean diameter 340 nm to assess the pulmonary phagocytosis response of rats to a single intratracheal instillation of these suspensions using optical, transmission electron, and semi-contact atomic force microscopy and biochemical indices measured in the bronchoalveolar lavage fluid. Although both nano and submicron ultrafine particles were adversely bioactive, the former were found to be more toxic for lungs as compared with the latter while evoking more pronounced defense recruitment of alveolar macrophages and especially of neutrophil leukocytes and more active phagocytosis. Based on our results and literature data, we consider both copper solubilization and direct contact with cellular organelles (mainly, mitochondria) of persistent particles internalized by phagocytes as probable mechanisms of their cytotoxicity. 相似文献
104.
The effects of rotary swaging and different heat treatment procedures on the W- and γ-phases behavior of PM 92.5W–5Ni–2.5Fe (wt.%) heavy alloy microalloyed with cobalt have been studied. The investigation was performed on sintered and cold rotary swaged samples deformed with area reduction from 5 to 30%. One batch of swaged samples was annealed in vacuum at 1473 K for 7.2 ks and then furnace-cooled to the room temperature, whereas another batch of swaged samples was previously deformed 30% and strain aged in argon and nitrogen in the temperature range between 473 and 1123 K for 3.6 ks. Strengthening of W- and γ-phases was investigated by applying microhardness measurements. Effects of the degree of deformation, parameters of heat treatment and strain aging on microstructural changes have been studied. Mechanical properties, hardness and microhardness of phases as a function of the degree of deformation and heat treatment were analyzed by applying statistical modeling. A correlation between deformation behavior of phases, effect of heat treatment and alloy properties was also discussed. 相似文献
105.
The adhesion of spheroidal particles to spherical drops is calculated and discussed in terms of an equilibrium-penetration index. The present study emphasizes the case of particles that are sufficiently large to affect the drop volume upon penetration. It is shown that the more elongated the particles, the steeper the dependence of the penetration index on the contact angle. The effect of line tension on nanoscale particles is considered. Positive line tensions increase the steepness of the dependence of penetration index on contact angle whereas negative line tensions decrease this dependence. In addition, the energy barrier caused by positive line tensions is presented and discussed. 相似文献
106.
A reanalysis of part of P. Podgorny and R. N. Shepard's (see record 1984-03057-001) data shows that reaction times (RTs) to attended and unattended squares are almost identical when the attended areas are nonunitary and that RTs are related to compactness for unitary attended areas but that this relation breaks down when attention is focused on nonunitary areas. The importance of the actual grid location of probes on RTs is also illustrated. The failure of compactness to reflect these aspects of the spatial nature of attention suggests that this metric is deficient when applied to the study of the spatial determinants of attention. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
Boris Dinzburg 《Sealing Technology》2001,2001(95):7-10
Carbonization of dynamic shaft-seals is a phenomenon that can result in oil leakage. The cause of carbonization has been studied, and suitable test methods have been developed. This article evaluates the phenomenon, looks at its implications, and provides details of these methods. 相似文献
108.
Michael A. Lebedev Boris V. Litvinov Michael M. Rusakov 《International Journal of Impact Engineering》1997,20(6-10):517-523
Results of the laboratory experimental investigation of the impact against the barriers of a number of materials by the shower of tungsten particles (striker) having density equal to 1 g/cm3, mass equal to 0.2 g and velocity up to 24 km/s as well as their head-on collision with relative velocity equal to 48 km/s, the results of analysis and prediction are presented. By using filming with illuminating from explosive the registration has been realized. Penetration, reactive pulse and the character of energy release during the shower deceleration were studied. In the experiment the process development picture (partial explosion during impact and subsequent penetration) which appeared to be intermediate between the complete explosion of the striker on the surface of the barrier and the explosion in the barrier after penetration has been realized. The hypervelocity collision process is also necessary to consider, to investigate and to develop as a system being possessed of its specific properties. The results presented in the report make possible to predict the explosion parameters for the wide range of strikers and barriers. 相似文献
109.
In a series of 6 experiments, two hypotheses were tested: that nominal heading perception is determined by the relative motion of images of objects positioned at different depths (R. F. Wang and J. E. Cutting, 1999) and that static depth information contributes to this determination. By manipulating static depth information while holding retinal-image motion constant during simulated self-movement, the authors found that static depth information played a role in determining perceived heading. Some support was also found for the involvement of R. F. Wang and J. E. Cutting's (1999) categories of object-image relative motion in determining perceived heading. However, results suggested an unexpected functional dominance of information about heading relative to apparently near objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
110.
The fundamental issues associated with solid oxide fuel cell (SOFC) durability have been reviewed with an emphasis on general features in SOFCs and respective anode and cathode related phenomena. As general features, physicochemical properties and cell performance degradation/failure are correlated and bridged by the electrode reaction mechanisms. Particular emphasis is placed on the elemental behaviour of gaseous impurities and the possible role of liquids formed from gaseous substances. The lifetime of a state-of-the-art Ni cermet anodes is limited by a variety of microstructural changes, which mainly result from material transport-, deactivation- and thermomechanical mechanisms. Anode degradation can mainly be influenced by processing, conceptual and operating parameters. Designing a redox stable anode is currently one of the biggest challenges for small scale SOFC systems. Degradation mechanisms of different cathode materials are reviewed with a focus on the intrinsic degradation of doped lanthanum manganites (e.g. LSM) and doped lanthanum ferro-cobaltites (LSCF). Manganese-based perovskites can be regarded to be sufficiently stable, while for the better performing LSCF cathodes some intrinsic degradation was detected. New materials that are supposed to combine a better stability and high performance are also shortly mentioned. 相似文献