全文获取类型
收费全文 | 437篇 |
免费 | 5篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 59篇 |
金属工艺 | 22篇 |
机械仪表 | 7篇 |
建筑科学 | 55篇 |
能源动力 | 3篇 |
轻工业 | 53篇 |
水利工程 | 10篇 |
无线电 | 14篇 |
一般工业技术 | 116篇 |
冶金工业 | 49篇 |
原子能技术 | 1篇 |
自动化技术 | 51篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 15篇 |
2014年 | 15篇 |
2013年 | 18篇 |
2012年 | 33篇 |
2011年 | 33篇 |
2010年 | 16篇 |
2009年 | 20篇 |
2008年 | 25篇 |
2007年 | 24篇 |
2006年 | 23篇 |
2005年 | 15篇 |
2004年 | 20篇 |
2003年 | 12篇 |
2002年 | 26篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有442条查询结果,搜索用时 10 毫秒
41.
Knut Hinkelmann Helge Hintze 《Annals of Mathematics and Artificial Intelligence》1997,20(1-4):335-356
Redundant computations in bottom‐up evaluation of logic programs and rule‐based systems can be avoided by caching intermediate
joins – i.e., partial rule instantiations – for later use. Joins can be cached either at representation level by program transformation
techniques introducing supplementary predicates or at implementation level by specialized implementation techniques using
internal memory cells. The efficiency of these state‐saving techniques depends on the selection of premises for storing the
joins. In this paper we first present a general program transformation technique for saving joins which heuristically reorders
subgoals and performs predicate splitting optimization, an extension of unfolding. This state‐saving transformation can be
applied for any goal‐directed and model‐generation evaluation. It does not require any information about the query. We show
that the program transformation approach is equivalent to the specialized state‐saving implementations known from production
systems and model‐generation theorem provers. To use the efficient and complete bottom‐up evaluation also for query answering,
we improve the supplementary extensions of Generalized Magic Sets and Magic Templates rewriting strategies by the presented
state‐saving transformation.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
42.
Zusammenfassung Der vorliegende Beitrag stellt die Ergebnisse eines Vergleichs von Software zur Verpackungslogistik vor. Es werden vier Programmpakete gegenübergestellt, die von deutschen bzw. englischen Firmen derzeit angeboten werden. 相似文献
43.
The microstructures of 0.40 w/s-ratio pastes of tricalcium silicate (C3S), alite and Portland cement have been studied at the hydration times 24 h and 1 month. A field-emission SEM (FE-SEM) was used to obtain high-resolution backscattered electron images. Comparison revealed no microstructural differences between C3S and alite, but there were considerable differences in microstructure between C3S and Portland cement pastes. The microstructure of the C3S paste was simpler than that of the Portland cement, and could be described by a few characteristic features. Distribution of the reaction products differed substantially in the two systems. While hollow shells (Hadley grains) were a prominent feature of the Portland cement paste, their occurrence was more limited in the C3S and alite pastes. Hollow shells were restricted to grains smaller than about 5 μm in the C3S and alite pastes, and gapped hollow shells were not a common feature. 相似文献
44.
Dr.-Ing. Dipl.-Wirt. Ing. Michael Friedewald Dr. rer. pol. Knut Blind Dr. rer. pol. Jakob Edler 《WIRTSCHAFTSINFORMATIK》2002,44(2):151-161
In this article we present the results of two empirical studies focusing on the structure and extent of the innovation activities of the German Software Industry and analyze distinctive features of Software Innovations. We distinguish the activities of the primary (core) Software Industry and secondary industries such as Mechanical and Electrical Engineering, Motor Industry and Telecommunications. A special focus is put on the question if innovations in Software are sequential, on the role of Open Source Software and the importance of interoperability. 相似文献
45.
Hans Erik Vatne PhD Roar Ørsund PhD Knut Marthinsen PhD Erik Nes 《Metallurgical and Materials Transactions A》1996,27(12):4133-4144
A physically based model for the evolution of recrystallization microstructures and textures during hot rolling of aluminum
is presented. The approach taken differs from similar models developed for steels. The present model is based on recent experimental
investigations directed toward identifying the nature of the nucleation sites for recrystallized grains of different crystallographic
orientations. Particle stimulated nucleation (PSN) and nucleation from cube bands and grain boundary regions have been incorporated
in the model. The multipass aspect complicates the modeling due to partial recrystallization between the rolling passes. Two
different approaches have been suggested to handle this. The model has been applied to predictions of recrystallization kinetics,
recrystallized grain sizes, and recrystallization textures during multipass hot rolling of aluminum. The predictions are reasonable
compared to experimental results. 相似文献
46.
The potentiation of masculine copulatory behavior in castrated male rats following systemic parachlorophenylalanine (PCPA) treatment was found to be dependent upon the strain of rat and the recency of castration. Wistar (W) and Sprague-Dawley (SD) males displayed a decline in behavioral responsiveness to PCPA treatment following castration, the Ws retaining their behavioral responsiveness longer than SDs. Castrated Ws were also behaviorally more responsive to androgen replacement than were SDs. Ovariectomized W and SD females receiving estrogen replacement displayed a strain difference in hormonal sensitivity. In tests for feminine copulatory behavior, ovariectomized Ws were behaviorally more sensitive to estrogen treatment than SDs. Ovariectomized and estrogen-primed females of both strains displayed potentiated lordotic behavior following chronic PCPA treatment. Concomitant treatment with dexamethasone to reduce adrenal steroid output abolished the potentiation of lordotic behavior found with PCPA treatment. (47 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
47.
48.
The paper describes the present state-of-the-art in analyses of ship vibration and elaborates on the difficulties regarding the finite element modelling.Some suggestions to enable better modelling of the structure, dependent on the aims of the analyses, the accuracy of input data, time and cost are given.It is shown that the main resonant frequencies of global and local structures may be predicted with sufficient accuracy, and a good indication of the forced response level may be obtained at the design stage. 相似文献
49.
Zusammenfassung Vergleichend-anatomische Untersuchungen des Holzes vonPopulus Simonii undPopulus robusta ergaben, da? die besten Unterscheidungsmerkmale für diese beiden Pappelarten Unterschiede in den Markstrahlh?hen und im Reichtum
an Strangparenchym sind. Auf Grund der vergleichend-physikalischen Untersuchung wird das Holz vonP. robusta als “ziemlich schwer”, das Holz vonP. Simonii als “mittelschwer” befunden. BeiP. Simonii besteht au?erdem eine Beziehung zwischen Rohwichte und Raumschwindung. Die Schwindung im Splint der Balsampappel ist wesentlich
geringer als diejenige beiP. robusta.
Comparative study on the anatomical and physical properties of wood ofPopulus Simonii andPopulus robusta
Summary Comparative anatomical studies on the wood of Populus Simonii and Populus robusta proved that their differences in ray height and richness in parenchyma are the most reliable characteristics for the distinction of these two poplar species. According to the results of comparative physical investigations the wood of P. robusta is designated as “rather heavy”, the wood of P. Simonii is found to be of “medium weight”. In the case of P. Simonii there is also a relationship between density and volume shrinkage. The shrinkage in the sapwood of balsam-poplar is considerably less than that of P. robusta.相似文献
50.
Die Auswirkungen des Querdrucks auf die Größe der Umformung nichtzug - und zugbeanspruchter Drähte werden theoretisch eingegrenzt, versuchsmäßig untermauert und graphisch dargestellt. Die Querpressung wird von Drähten gleicher Art ausgeübt. Die Einflüsse des Querdruckes aus der Verseilung auf das Tragverhalten eines vollverschlossenen Spiralseiles werden anhand eines Beispieles diskutiert. 相似文献