全文获取类型
收费全文 | 4253篇 |
免费 | 448篇 |
国内免费 | 400篇 |
专业分类
电工技术 | 166篇 |
综合类 | 381篇 |
化学工业 | 39篇 |
金属工艺 | 70篇 |
机械仪表 | 428篇 |
建筑科学 | 71篇 |
矿业工程 | 38篇 |
能源动力 | 19篇 |
轻工业 | 26篇 |
水利工程 | 24篇 |
石油天然气 | 12篇 |
武器工业 | 60篇 |
无线电 | 211篇 |
一般工业技术 | 175篇 |
冶金工业 | 237篇 |
原子能技术 | 5篇 |
自动化技术 | 3139篇 |
出版年
2024年 | 11篇 |
2023年 | 40篇 |
2022年 | 74篇 |
2021年 | 77篇 |
2020年 | 64篇 |
2019年 | 65篇 |
2018年 | 47篇 |
2017年 | 59篇 |
2016年 | 99篇 |
2015年 | 128篇 |
2014年 | 170篇 |
2013年 | 200篇 |
2012年 | 210篇 |
2011年 | 227篇 |
2010年 | 215篇 |
2009年 | 266篇 |
2008年 | 303篇 |
2007年 | 305篇 |
2006年 | 351篇 |
2005年 | 300篇 |
2004年 | 257篇 |
2003年 | 248篇 |
2002年 | 209篇 |
2001年 | 172篇 |
2000年 | 155篇 |
1999年 | 119篇 |
1998年 | 122篇 |
1997年 | 94篇 |
1996年 | 87篇 |
1995年 | 75篇 |
1994年 | 75篇 |
1993年 | 62篇 |
1992年 | 52篇 |
1991年 | 49篇 |
1990年 | 26篇 |
1989年 | 30篇 |
1988年 | 19篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1979年 | 2篇 |
1975年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1962年 | 2篇 |
1961年 | 2篇 |
1959年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有5101条查询结果,搜索用时 15 毫秒
1.
In architectural design, surface shapes are commonly subject to geometric constraints imposed by material, fabrication or assembly. Rationalization algorithms can convert a freeform design into a form feasible for production, but often require design modifications that might not comply with the design intent. In addition, they only offer limited support for exploring alternative feasible shapes, due to the high complexity of the optimization algorithm.We address these shortcomings and present a computational framework for interactive shape exploration of discrete geometric structures in the context of freeform architectural design. Our method is formulated as a mesh optimization subject to shape constraints. Our formulation can enforce soft constraints and hard constraints at the same time, and handles equality constraints and inequality constraints in a unified way. We propose a novel numerical solver that splits the optimization into a sequence of simple subproblems that can be solved efficiently and accurately.Based on this algorithm, we develop a system that allows the user to explore designs satisfying geometric constraints. Our system offers full control over the exploration process, by providing direct access to the specification of the design space. At the same time, the complexity of the underlying optimization is hidden from the user, who communicates with the system through intuitive interfaces. 相似文献
2.
3.
H. D. Saltzstein and T. Kasachkoff (2004) (see record 2004-21519-004) critique the social intuitionist model (J. Haidt, 2001) (see record 2001-18918-008), but the model they critique is a stripped-down version that should be called the "possum" model. They make 3 charges about the possum model that are not true about the social intuitionist model: that it includes no role for reasoning, that it reduces social influence to compliance, and that it does not take a developmental perspective. After a defense of the honor of the social intuitionist model, this article raises 2 areas of legitimate dispute: the scope and nature of moral reasoning and the usefulness of appealing to innate ideas, rather than to learning and reasoning, as the origin of moral knowledge. This article presents 3 clusters of innate moral intuitions, related to sympathy, hierarchy, and reciprocity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Inaki Arrazola Agn s Plainfoss Henri Prade Claudette Testemale 《Information Systems》1989,14(6):487-492
This paper presents different approaches which enable a data base management system to obtain a plausible fuzzy estimate for an attribute value of an item for which the information is not explicitly stored in the data base. This can be made either by a kind of analogical reasoning from information about particular items or by means of expert rules which specify the (fuzzy) sets of possible values of the attribute under consideration, for various classes of items. Another kind of expert rules enables the system to compute an estimate from the attribute value of another item provided that, in other respects, this latter item sufficiently resembles the item, the value of which we are interested in; then these expert rules are used either for controlling the analogical reasoning process or for enlarging the scope of application of the first kind of expert rules. The different approaches are discussed in the framework of possibility theory. 相似文献
5.
Maria Zemankova 《Information Systems》1989,14(6):473-486
FILIP (fuzzy intelligent learning information processing) system is designed with the goal to model human information processing. The issues addressed are uncertain knowledge representation and approximate reasoning based on fuzzy set theory, and knowledge acquisition by “being told” or by “learning from examples”. Concepts that can be “learned” by the system can be imprecise (fuzzy), or the knowledge can be incomplete. In the latter case, FILIP uses the concept of similarity to extrapolate the knowledge to cases that were not covered by examples provided by the user. Concepts are stored in the Knowledge Base and employed in intelligent query processing, based on flexible inference that supports approximate matches between the data in the database and the query.
The architecture of FILIP is discussed, the learning algorithm is described, and examples of the system's performance in the knowledge acquisition and querying modes, together with its explanatory capabilities are shown. 相似文献
6.
The physical gestures that operate music instruments are responsible for the qualities of the sound being produced in a performance.
Gestural information is thereby crucial for a model of music performance, paired with a model of sound synthesis where this
information is applied. The highly constrained nature of performers gestures makes this task suitable to be modeled via a
constraint-based approach, coupled with a strategy aimed at maximizing the gestural comfort of performers. We illustrate the
problem representation, the search strategy and a validation of the model against human performance. 相似文献
7.
8.
9.
We study the computational complexity of the qualitative algebra which is a temporal constraint formalism that combines the point algebra, the point-interval algebra and Allen's interval algebra. We identify all tractable fragments and show that every other fragment is NP-complete. 相似文献
10.
Axel Wabenhorst 《Theoretical computer science》2003,300(1-3):181-207
The Timed Interval Calculus, a timed-trace formalism based on set theory, is introduced. It is extended with an induction law and a unit for concatenation, which facilitates the proof of properties over trace histories. The effectiveness of the extended Timed Interval Calculus is demonstrated via a benchmark case study, the mine pump. Specifically, a safety property relating to the operation of a mine shaft is proved, based on an implementation of the mine pump and assumptions about the environment of the mine. 相似文献