全文获取类型
收费全文 | 6506篇 |
免费 | 315篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 73篇 |
综合类 | 7篇 |
化学工业 | 1534篇 |
金属工艺 | 107篇 |
机械仪表 | 148篇 |
建筑科学 | 327篇 |
矿业工程 | 9篇 |
能源动力 | 226篇 |
轻工业 | 540篇 |
水利工程 | 61篇 |
石油天然气 | 26篇 |
武器工业 | 2篇 |
无线电 | 581篇 |
一般工业技术 | 1107篇 |
冶金工业 | 913篇 |
原子能技术 | 34篇 |
自动化技术 | 1143篇 |
出版年
2023年 | 67篇 |
2022年 | 107篇 |
2021年 | 173篇 |
2020年 | 123篇 |
2019年 | 125篇 |
2018年 | 175篇 |
2017年 | 157篇 |
2016年 | 192篇 |
2015年 | 160篇 |
2014年 | 223篇 |
2013年 | 406篇 |
2012年 | 366篇 |
2011年 | 428篇 |
2010年 | 325篇 |
2009年 | 369篇 |
2008年 | 353篇 |
2007年 | 367篇 |
2006年 | 262篇 |
2005年 | 253篇 |
2004年 | 204篇 |
2003年 | 183篇 |
2002年 | 157篇 |
2001年 | 105篇 |
2000年 | 111篇 |
1999年 | 107篇 |
1998年 | 103篇 |
1997年 | 111篇 |
1996年 | 80篇 |
1995年 | 100篇 |
1994年 | 87篇 |
1993年 | 63篇 |
1992年 | 64篇 |
1991年 | 31篇 |
1990年 | 46篇 |
1989年 | 65篇 |
1988年 | 49篇 |
1987年 | 37篇 |
1986年 | 51篇 |
1985年 | 57篇 |
1984年 | 44篇 |
1983年 | 54篇 |
1982年 | 35篇 |
1981年 | 35篇 |
1980年 | 32篇 |
1979年 | 26篇 |
1978年 | 19篇 |
1977年 | 17篇 |
1976年 | 24篇 |
1975年 | 29篇 |
1974年 | 22篇 |
排序方式: 共有6838条查询结果,搜索用时 15 毫秒
61.
Ma Shizhou Beazley Karen F. Nussey Patrick Greene Christopher S. 《Water Resources Management》2021,35(14):4825-4840
Water Resources Management - The Active River Area (ARA) is a spatial approach for identifying the extent of functional riparian area. Given known limitations in terms of input elevation data... 相似文献
62.
Stream habitat restoration is an important tool for fisheries management in impaired lotic systems. Although small‐scale benefits of stream habitat restoration are commonly investigated, it is difficult to demonstrate population effects. The Pahsimeroi River Chinook salmon Oncorhynchus tshawytscha population was previously restricted to the lower portion of the river by multiple irrigation structures. To address fish passage issues, a combination of restoration projects was initiated including barrier removals, instream flow enhancements and installation of fish screens on diversions. The largest barrier was removed in 2009, more than doubling the amount of accessible linear habitat. We hypothesized restoration efforts would expand the distribution of spawning salmon in the Pahsimeroi River watershed, leading to a broader distribution of juveniles. We also hypothesized a broader juvenile distribution would have population effects by reducing the prevalence of density‐dependent growth and survival. Redds were documented in newly accessible habitat immediately following barrier removal and accounted for a median of 42% of all redds in the Pahsimeroi River watershed during 2009–2015. Snorkel surveys also documented juvenile rearing in newly accessible habitat. Juvenile productivity increased from a median of 64 smolts/female spawner for brood years 2002–2008 to 99 smolts/female spawner for brood years 2009–2014. Overall, results suggested increased habitat accessibility in the Pahsimeroi River broadened the distribution of spawning adult and rearing juvenile salmon and reduced the effects of density‐dependent survival. Large‐scale stream restoration efforts can have a population effect. Despite the large‐scale effort and response, habitat restoration alone is likely not sufficient to restore this population. 相似文献
63.
Artificial intelligence (AI) has been heralded by many as the next source of business value. Grounded on the resource-based theory of the firm and on recent work on AI at the organizational context, this study (1) identifies the AI-specific resources that jointly create an AI capability and provides a definition, (2) develops an instrument to capture the AI capability of the firms, and (3) examines the relationship between an AI capability and organizational creativity and performance. Findings empirically support the suggested theoretical framework and corresponding instrument and provide evidence that an AI capability results in increased organizational creativity and performance. 相似文献
64.
Sidney D'Mello Andrew Olney Claire Williams Patrick Hays 《International journal of human-computer studies》2012,70(5):377-398
We developed an intelligent tutoring system (ITS) that aims to promote engagement and learning by dynamically detecting and responding to students' boredom and disengagement. The tutor uses a commercial eye tracker to monitor a student's gaze patterns and identify when the student is bored, disengaged, or is zoning out. The tutor then attempts to reengage the student with dialog moves that direct the student to reorient his or her attentional patterns towards the animated pedagogical agent embodying the tutor. We evaluated the efficacy of the gaze-reactive tutor in promoting learning, motivation, and engagement in a controlled experiment where 48 students were tutored on four biology topics with both gaze-reactive and non-gaze-reactive (control condition) versions of the tutor. The results indicated that: (a) gaze-sensitive dialogs were successful in dynamically reorienting students’ attentional patterns to the important areas of the interface, (b) gaze-reactivity was effective in promoting learning gains for questions that required deep reasoning, (c) gaze-reactivity had minimal impact on students’ state motivation and on self-reported engagement, and (d) individual differences in scholastic aptitude moderated the impact of gaze-reactivity on overall learning gains. We discuss the implications of our findings, limitations, future work, and consider the possibility of using gaze-reactive ITSs in classrooms. 相似文献
65.
Peter Demeester Burak Bilgin Patrick De Causmaecker Greet Vanden Berghe 《Journal of Scheduling》2012,15(1):83-103
Many researchers studying examination timetabling problems focus on either benchmark problems or problems from practice encountered
in their institutions. Hyperheuristics are proposed as generic optimisation methods which explore the search space of heuristics
rather than direct solutions. In the present study, the performance of tournament-based hyperheuristics for the exam timetabling
problem are investigated. The target instances include both the Toronto and ITC 2007 benchmarks and the examination timetabling
problem at KAHO Sint-Lieven (Ghent, Belgium). The Toronto and ITC 2007 benchmarks are post-enrolment-based examination timetabling
problems, whereas the KAHO Sint-Lieven case is a curriculum-based examination timetabling problem. We drastically improve
the previous (manually created) solution for the KAHO Sint-Lieven problem by generating a timetable that satisfies all the
hard and soft constraints. We also make improvements on the best known results in the examination timetabling literature for
seven out of thirteen instances for the To ronto benchmarks. The results are competitive with those of the finalists of the
examination timetabling track of the International Timetabling Competition. 相似文献
66.
Monique Jackson Ines Benkhemis Micka?l Begon Philippe Sardain Claude Vallée Patrick Lacouture 《Multibody System Dynamics》2012,28(3):225-237
Optimal synthesis of human movement or the prediction of the kinematics of a new movement require not only that the multi-body system be modeled but also that a performance criterion is specified. For sub-maximal movements the selection of a suitable performance criterion, able to generate realistic dynamic behavior is difficult. A two-dimensional simulation model of the take-off phase of a sub-maximal long jump was developed to study the effect of criterion choice on the realism of simulated movements. A parametric optimization technique was employed to obtain solutions to the constrained equations of motion. Seven different criteria were evaluated, by comparing simulated movements with an actual performance, to identify the criterion which most closely approximated that spontaneously minimized by the athlete. Synthesis of the take-off phase of a sub-maximal long jump was found to be sensitive to the chosen criterion, with a criterion based on minimizing joint intersegmental forces found to perform well. 相似文献
67.
Patrick Heymans Quentin Boucher Andreas Classen Arnaud Bourdoux Laurent Demonceau 《International Journal on Software Tools for Technology Transfer (STTT)》2012,14(5):553-566
Software product line engineering seeks to systematise reuse when developing families of similar software systems so as to minimise development time, cost and defects. To realise variability at the code level, product line methods classically advocate usage of inheritance, components, frameworks, aspects or generative techniques. However, these might require unaffordable paradigm shifts for developers if the software was not thought at the outset as a product line. Furthermore, these techniques can be conflicting with a company’s coding practices or external regulations. These concerns were the motivation for the industry–university collaboration described in this paper in which we developed a minimally intrusive coding technique based on tags. The approach was complemented with traceability from code to feature diagrams which were exploited for automated configuration. It is supported by a toolchain and is now in use in the partner company for the development of flight-grade satellite communication software libraries. 相似文献
68.
Successful planning and control of robots strongly depends on the quality of kinematic models, which define mappings between
configuration space (e.g. joint angles) and task space (e.g. Cartesian coordinates of the end effector). Often these models
are predefined, in which case, for example, unforeseen bodily changes may result in unpredictable behavior. We are interested
in a learning approach that can adapt to such changes—be they due to motor or sensory failures, or also due to the flexible
extension of the robot body by, for example, the usage of tools. We focus on learning locally linear forward velocity kinematics
models by means of the neuro-evolution approach XCSF. The algorithm learns self-supervised, executing movements autonomously
by means of goal-babbling. It preserves actuator redundancies, which can be exploited during movement execution to fulfill
current task constraints. For detailed evaluation purposes, we study the performance of XCSF when learning to control an anthropomorphic
seven degrees of freedom arm in simulation. We show that XCSF can learn large forward velocity kinematic mappings autonomously
and rather independently of the task space representation provided. The resulting mapping is highly suitable to resolve redundancies
on the fly during inverse, goal-directed control. 相似文献
69.
Qishi Wu Mengxia Zhu Yi Gu Patrick Brown Xukang Lu Wuyin Lin Yangang Liu 《Journal of Grid Computing》2012,10(3):367-393
Next-generation scientific applications feature complex workflows comprised of many computing modules with intricate inter-module dependencies. Supporting such scientific workflows in wide-area networks especially Grids and optimizing their performance are crucial to the success of collaborative scientific discovery. We develop a Scientific Workflow Automation and Management Platform (SWAMP), which enables scientists to conveniently assemble, execute, monitor, control, and steer computing workflows in distributed environments via a unified web-based user interface. The SWAMP architecture is built entirely on a seamless composition of web services: the functionalities of its own are provided and its interactions with other tools or systems are enabled through web services for easy access over standard Internet protocols while being independent of different platforms and programming languages. SWAMP also incorporates a class of efficient workflow mapping schemes to achieve optimal end-to-end performance based on rigorous performance modeling and algorithm design. The performance superiority of SWAMP over existing workflow mapping schemes is justified by extensive simulations, and the system efficacy is illustrated by large-scale experiments on real-life scientific workflows for climate modeling through effective system implementation, deployment, and testing on the Open Science Grid. 相似文献
70.
Dr. Armin Welker Dr. Christian Kersten Dr. Christin Müller Dr. Ramakanth Madhugiri Collin Zimmer Patrick Müller Robert Zimmermann Stefan Hammerschmidt Hannah Maus Prof. John Ziebuhr Prof. Christoph Sotriffer Prof. Tanja Schirmeister 《ChemMedChem》2021,16(2):340-354
Inhibition of coronavirus (CoV)-encoded papain-like cysteine proteases (PLpro) represents an attractive strategy to treat infections by these important human pathogens. Herein we report on structure-activity relationships (SAR) of the noncovalent active-site directed inhibitor (R)-5-amino-2-methyl-N-(1-(naphthalen-1-yl)ethyl) benzamide ( 2 b ), which is known to bind into the S3 and S4 pockets of the SARS-CoV PLpro. Moreover, we report the discovery of isoindolines as a new class of potent PLpro inhibitors. The studies also provide a deeper understanding of the binding modes of this inhibitor class. Importantly, the inhibitors were also confirmed to inhibit SARS-CoV-2 replication in cell culture suggesting that, due to the high structural similarities of the target proteases, inhibitors identified against SARS-CoV PLpro are valuable starting points for the development of new pan-coronaviral inhibitors. 相似文献