全文获取类型
收费全文 | 1374篇 |
免费 | 72篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 273篇 |
金属工艺 | 12篇 |
机械仪表 | 18篇 |
建筑科学 | 105篇 |
矿业工程 | 2篇 |
能源动力 | 17篇 |
轻工业 | 194篇 |
水利工程 | 14篇 |
石油天然气 | 7篇 |
无线电 | 82篇 |
一般工业技术 | 234篇 |
冶金工业 | 286篇 |
原子能技术 | 2篇 |
自动化技术 | 198篇 |
出版年
2023年 | 16篇 |
2022年 | 23篇 |
2021年 | 59篇 |
2020年 | 30篇 |
2019年 | 51篇 |
2018年 | 29篇 |
2017年 | 44篇 |
2016年 | 53篇 |
2015年 | 46篇 |
2014年 | 54篇 |
2013年 | 107篇 |
2012年 | 68篇 |
2011年 | 110篇 |
2010年 | 90篇 |
2009年 | 76篇 |
2008年 | 97篇 |
2007年 | 64篇 |
2006年 | 56篇 |
2005年 | 50篇 |
2004年 | 38篇 |
2003年 | 45篇 |
2002年 | 38篇 |
2001年 | 18篇 |
2000年 | 16篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 16篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1966年 | 2篇 |
1963年 | 2篇 |
排序方式: 共有1448条查询结果,搜索用时 15 毫秒
31.
Angela Bonifati Elaine Chang Terence Ho Laks V. S. Lakshmanan Rachel Pottinger Yongik Chung 《The VLDB Journal The International Journal on Very Large Data Bases》2010,19(2):231-256
Peers in a peer-to-peer data management system often have heterogeneous schemas and no mediated global schema. To translate queries across peers, we assume each peer provides correspondences between its schema and a small number of other peer schemas. We focus on query reformulation in the presence of heterogeneous XML schemas, including data–metadata conflicts. We develop an algorithm for inferring precise mapping rules from informal schema correspondences. We define the semantics of query answering in this setting and develop query translation algorithm. Our translation handles an expressive fragment of XQuery and works both along and against the direction of mapping rules. We describe the HePToX heterogeneous P2P XML data management system which incorporates our results. We report the results of extensive experiments on HePToX on both synthetic and real datasets. We demonstrate our system utility and scalability on different P2P distributions. 相似文献
32.
A new semantics in terms of mean field equations is presented for WSCCS (Weighted Synchronous Calculus of Communicating Systems). The semantics captures the average behaviour of the system over time, but without computing the entire state space, therefore avoiding the state space explosion problem. This allows easy investigation of models with large numbers of components. The new semantics is shown to be equivalent to the standard Discrete Time Markov Chain semantics of WSCCS as the number of processes tends to infinity. The method of deriving the semantics is illustrated with examples drawn from biology and from computing. 相似文献
33.
Rachel Cardell-Oliver 《Formal Aspects of Computing》2000,12(5):350-371
A method is introduced for testing the conformance of implemented real-time systems to timed automata specifications. Uppaal
timed automata are transformed into testable timed transition systems (TTTSs) using a test view. Fault hypotheses and a test
generation algorithm for TTTSs are defined. Results of applying the method are presented.
Received October 1999 / Accepted in revised form November 2000 相似文献
34.
Maria Koutantji Peter McCulloch Shabnam Undre Sanjay Gautama Simon Cunniffe Nick Sevdalis Rachel Davis Piers Thomas Charles Vincent Ara Darzi 《Cognition, Technology & Work》2008,10(4):275-285
We developed a module for surgical team training using briefings in simulated crisis scenarios and here we report preliminary
findings. Nine surgical teams (34 trainees) participated in a pre-training simulation, followed by an interactive workshop
on briefing and checklists, and then a post-training simulation. Both technical and non-technical skills were assessed via
observation during simulations by expert trainers who provided feedback on performances at the end of simulation. Trainees
also reported their attitudes to briefings and evaluated the training. Pre-training attitudes to briefing were positive, some
of which improved post-training and trainees’ evaluation of the training was positive. Surgeons’ technical skill improved
significantly post-training, but their decision-making skill was rated lower than other non-technical skills, compared to
other trainees. The training did not appear to greatly improve non-technical skill performance. Training surgical teams in
simulation is feasible but much more work is needed on measurement development and training strategy to confirm its efficacy
and utility. 相似文献
35.
Steve Whittaker Simon Tucker Kumutha Swampillai Rachel Laban 《Personal and Ubiquitous Computing》2008,12(3):197-221
Although many recent systems have been built to support Information Capture and Retrieval (ICR), these have not generally
been successful. This paper presents studies that evaluate two different hypotheses for this failure, firstly that systems
fail to address user needs and secondly that they provide only rudimentary support for ICR. Having first presented a taxonomy
of different systems built to support ICR, we then describe a study that attempts to identify user needs for ICR. On the basis
of that study we carried out two user-oriented evaluations. In the first, we carried out a task-based evaluation of a state-of-the-art
ICR system, finding that it failed to provide users with abstract ways to view meetings data, and did not present users with
information categories that they considered to be important. In a second study, we introduce a new method for comparative
evaluation of different techniques for accessing meetings data. The second study showed that simple interface techniques that
extracted key information from meetings were effective in allowing users to extract gist from meetings data. We conclude with
a discussion of outstanding issues and future directions for ICR research. 相似文献
36.
Rachel Edita Oñate Roxas Allan Borra Charibeth Ko Cheng Nathalie Rose Lim Ethel Chuajoy Ong Michelle Wendy Tan 《Language Resources and Evaluation》2008,42(2):183-195
In this paper, we present the building of various language resources for a multi-engine bi-directional English-Filipino Machine
Translation (MT) system. Since linguistics information on Philippine languages are available, but as of yet, the focus has
been on theoretical linguistics and little is done on the computational aspects of these languages, attempts are reported
here on the manual construction of these language resources such as the grammar, lexicon, morphological information, and the
corpora which were literally built from almost non-existent digital forms. Due to the inherent difficulties of manual construction,
we also discuss our experiments on various technologies for automatic extraction of these resources to handle the intricacies
of the Filipino language, designed with the intention of using them for the MT system. To implement the different MT engines
and to ensure the improvement of translation quality, other language tools (such as the morphological analyzer and generator,
and the part of speech tagger) were developed. 相似文献
37.
Link-based information structures such as the web can be enhanced through the addition of hotlinks. Assume that each node in the information structure is associated with a weight representing the access frequency of the node by users. In order to access a particular node, the user must follow a path leading to it from the root. By adding new hotlinks to the tree, it may be possible to reduce the access cost of the system, namely, the expected number of steps needed to reach a leaf from the root, assuming the user can decide which hotlinks to follow in each step. The hotlink assignment problem involves finding a set of hotlinks (with at most K=O(1) hotlinks emanating from every node) maximizing the gain in the expected cost. The paper addresses this problem in two user models, namely, the traditional clairvoyant user model employed in [P. Bose, J. Czyzowicz, L. Gasieniec, E. Kranakis, D. Krizanc, A. Pelc, M.V. Martin, Strategies for hotlink assignments, in: Proc. 11th Symp. on Algorithms and Computation, 2000, pp. 23–34; E. Kranakis, D. Krizanc, S. Shende, Approximating hotlink assignments, in: Proc. 12th Symp. on Algorithms and Computation, 2001, pp. 756–767; P. Bose, D. Krizanc, S. Langerman, P. Morin, Asymmetrical communication protocols via hotlink assignments, in: Proc. 9th Colloq. on Structural Information and Communication Complexity, 2002, pp. 33–39; R. Matichin, D. Peleg, Approximation algorithm for hotlink assignments in web directories, in: Proc. Workshop on Algorithms and Data Structures, 2003, pp. 271–280] and the more realistic greedy user model recently introduced in [O. Gerstel, S. Kutten, R. Matichin, D. Peleg, Hotlink enhancement algorithms for web directories, in: Proc. 14th Symp. on Algorithms and Computation, 2003, pp. 68–77], and presents a polynomial time 2-approximation algorithm for the hotlink assignment problem on rooted directed trees. 相似文献
38.
Dr. P. Pottinger 《Computing》1976,17(2):163-167
Some estimations for the relative projection constantP(∏ n+k k ,Csik[a,b]) are given. By constructing an associated polynomial operatorL n :C 0[a,b]→∏ n 0 to a given polynomial operatorH n+k :C k [a,b]→∏ n+k k we get a lower bound for the projection constant. An upper bound forP(∏ n+k k ,C k [a,b]) is obtained by the determination of the norms of appropriate polynomial operatorsP n+k :C k [a,b]→∏ n+k k . Further we give a convergence property for the sequence (P n+k ) n∈?. 相似文献
39.
Love John M.; Kisker Ellen Eliason; Ross Christine; Raikes Helen; Constantine Jill; Boller Kimberly; Brooks-Gunn Jeanne; Chazan-Cohen Rachel; Tarullo Louisa Banks; Brady-Smith Christy; Fuligni Allison Sidle; Schochet Peter Z.; Paulsell Diane; Vogel Cheri 《Canadian Metallurgical Quarterly》2005,41(6):885
Early Head Start, a federal program begun in 1995 for low-income pregnant women and families with infants and toddlers, was evaluated through a randomized trial of 3,001 families in 17 programs. Interviews with primary caregivers, child assessments, and observations of parent-child interactions were completed when children were 3 years old. Caregivers were diverse in race-ethnicity, language, and other characteristics. Regression-adjusted impact analyses showed that 3-year-old program children performed better than did control children in cognitive and language development, displayed higher emotional engagement of the parent and sustained attention with play objects, and were lower in aggressive behavior. Compared with controls, Early Head Start parents were more emotionally supportive, provided more language and learning stimulation, read to their children more, and spanked less. The strongest and most numerous impacts were for programs that offered a mix of home-visiting and center-based services and that fully implemented the performance standards early. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
40.
Some aspects of "second-generation" Positive Psychology are analyzed and their origins explored. In particular, Seligman's importation of the concept of eudaimonia from Aristotelian ethics is critiqued and found to be problematic. This conclusion is reached through an examination of the concept of eudaimonia as it was employed in ancient philosophy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献