全文获取类型
收费全文 | 971篇 |
免费 | 41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 | 377篇 |
金属工艺 | 27篇 |
机械仪表 | 21篇 |
建筑科学 | 34篇 |
矿业工程 | 3篇 |
能源动力 | 26篇 |
轻工业 | 141篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
武器工业 | 1篇 |
无线电 | 65篇 |
一般工业技术 | 168篇 |
冶金工业 | 14篇 |
原子能技术 | 8篇 |
自动化技术 | 112篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 66篇 |
2021年 | 80篇 |
2020年 | 22篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 26篇 |
2016年 | 44篇 |
2015年 | 29篇 |
2014年 | 43篇 |
2013年 | 72篇 |
2012年 | 63篇 |
2011年 | 65篇 |
2010年 | 43篇 |
2009年 | 42篇 |
2008年 | 42篇 |
2007年 | 36篇 |
2006年 | 27篇 |
2005年 | 26篇 |
2004年 | 26篇 |
2003年 | 17篇 |
2002年 | 24篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 11篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1971年 | 1篇 |
排序方式: 共有1016条查询结果,搜索用时 15 毫秒
101.
Metadata requirements for digital museum environments 总被引:1,自引:0,他引:1
Manjula Patel Martin White Nicholaos Mourkoussis Krzysztof Walczak Rafal Wojciechowski Jacek Chmielewski 《International Journal on Digital Libraries》2005,5(3):179-192
We describe a system which addresses all the processes involved in digitally acquiring, modelling, storing, manipulating and creating virtual exhibitions from 3D museum artefacts. More specifically, we examine the significance of metadata in enabling and supporting all of these processes and describe the extensive facilities provided for authoring, maintaining and managing metadata. The development of the system has been heavily influenced by factors relating to interoperability, standards, museum best practice and feedback from two museum pilot sites. Finally, we briefly consider the system in the wider context of applications such as virtual learning environments and distributed repositories of archives. 相似文献
102.
Jacek M. Czaplicki 《Microelectronics Reliability》1985,25(4):695-698
In the paper the model of reliability diagnostic of renewal objects which exploitation process can be described as the interrupting renewal process with the finite time of repair is discussed. The essential relationships between reliability of object and diagnostic parameters are presented. 相似文献
103.
In this paper we present a computational model of electrical conductivity processes via variable range hopping of electrons between localized states (‘sites’) in quasi one-dimensional disordered systems. For two, slightly different models, the temperature dependence of the conductivity of parallel connected systems of filaments and of quasi-infinite, single filaments are discussed and compared with theoretical and experimental results. 相似文献
104.
Jacek A. Michalski 《化学工程与技术》1995,18(6):434-439
A theoretical analysis is presented for the time-dependent vertical motion of spherical particles in a gas stream. Laminar, transitional and turbulent flows are considered, and equations are developed to predict particle velocity and distance travelled as functions of time in both stagnant and slowly-moving gases. In both cases the equations are shown not to be universally applicable, and algorithms for estimating the limits within which they remain valid are briefly presented. 相似文献
105.
This paper describes two ideas and sample simulation results of a heuristic reinforcement-learning system and its application to the problem of digital computer control of a simple nuclear plant model. The idea of the system is interconnection between the well known reactor control heuristic rules [8,9], and the reinforcement learning algorithms [4,5]. The control signal is proposed as a vector depending on complex physical properties of the plant. Such an approach is far more flexible than deterministic or stochastic techniques when dealing with unknown processes and novel control situations. 相似文献
106.
107.
Jacek Chroscielewski Zbigniew Cywinski Ireneusz Kreja Stanislaw Uminski 《Computers & Structures》1983,17(1):37-44
Computer aided finite element analysis has been applied to evaluate the structural behavior of a solid plate representing statically certain box-type construction of a dry dock gate. Possible comparison of particular results following from different procedures, valid for constant plate stiffness and rigid supports, has been performed and the distribution of reactions for variable plate stiffness, within two different numerical accuracies, has been studied. For practical requirements the nonlinear elastic flexibility of dock gate packing has been taken into account and an adequate numerical step-by-step approach, satisfying the considered material characteristics, developed. For last case the deflections, reactions, and internal forces have been examined in detail and a comparison with those for rigid supports presented. 相似文献
108.
A numerical model for the hopping conductivity in 3-D disordered systems is presented. The relation between variable-range hopping conductivity and temperature for the low-temperature range is found. The advantage of the proposed model is that the size of the system investigated is not limited by the computer memory. 相似文献
109.
110.
Waluk J 《Accounts of chemical research》2006,39(12):945-952
Owing to short distances between the inner nitrogen atoms and, therefore, strong intramolecular hydrogen bonds, porphycenes display completely different tautomeric properties than porphyrins, their constitutional isomers. Tunneling splitting caused by delocalization of two inner hydrogen atoms is observed for porphycenes isolated in supersonic jets. The barrier to tautomerization is higher in the lowest excited singlet state than in the ground state. Still, rapid exchange of inner hydrogen atoms is detected in S1. The mechanism of tautomerization involves synchronous double hydrogen tunneling, activated by excitation of a low-frequency mode, which modulates the NH...N separation. This separation can also be strongly altered by peripheral substitution. In porphycenes with alkyl substituents on the ethylene bridges, the NH...N distances become extremely small. For these derivatives, both trans and cis tautomeric forms are detected. Tautomerism in porphycenes was also monitored on a single-molecule level. 相似文献