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171.
ULTIMA is a project which proposes to use superfluid 3He as a sensitive medium for direct dark matter search. In this paper we report on new, detailed calibrations of our bolometric cells as a function of the magnetic field. An influence on the order of 20% on the peak height after an energy deposition is observed for magnetic fields up to 330 mT. Simultaneous measurements of neutron capture and heater events, releasing both a well defined energy, show that the effect is similar for both, and that it is possible to maintain a good calibration by an appropriate correction.   相似文献   
172.
At what layer does mobility belong?   总被引:4,自引:0,他引:4  
Internetworking is a complex problem, traditionally tackled by splitting responsibilities between several layers of protocols arranged in a stack. A shortcoming of the current Internet suite's layers is that the responsibilities of individual layers are somewhat ill defined. The result is that frequently a feature may cause problems for higher layers when it unexpectedly exists lower in the stack, or may be unnecessarily and inefficiently implemented in multiple layers. Mobility is one such feature with no well defined place in classical protocol stacks. If a link layer hands over between two distinctly administered networks, a network layer protocol will likely need to acquire a new address. Similarly, if mobility is implemented at the network layer, such as with mobile IP, transport layer protocols must be prepared to deal with a slew of problems (rapid changes in available capacity and delay, the asymmetry of triangle routes, and security policies, to name a few). Code for higher-level protocols (above transport) is less frequently reused, so higher-layer mobility schemes fail to leverage the large base of TCP sockets code. We discuss the various strengths and weaknesses of implementing mobility at three different layers of the protocol stack, concluding that a transport layer mobility scheme is likely to suit today's mobile Internet users best, and that ideally there should be more communication between layers to avoid conflict and inefficiency.  相似文献   
173.
This study examined theoretical, methodological, and statistical problems involved in evaluating the outcome of aggression on the playground for a universal preventive intervention for conduct disorder. Moderately aggressive children were hypothesized most likely to benefit. Aggression was measured on the playground using observers blind to the group status of the children. Behavior was microcoded in real time to minimize potential expectancy biases. The effectiveness of the intervention was strongly relate to initial levels of aggressiveness. The most aggressive children improved the most. Models that incorporated corrections for low reliability (the ratio of variance due to true time-stable individual differences to total variance) and censoring (a floor effect in the rate data due to short periods of observation) obtained effect sizes 5 times larger than models without such corrections with respect to children who were initially 2 SDs above the mean on aggressiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
174.
A novel hepta-substituted beta-cyclodextrin bearing the methoxyethylamine group linked to the upper cyclodextrin rim was successfully used as a chiral selector for enantiomeric separation of non-steroidal anti-inflammatory drugs (NSAIDs) and phenoxypropionic acid herbicides (PPAHs). Separation parameters such as pH and concentration were found to have major influences on enantiomeric resolution of the NSAIDs and PPAHs. Results indicate that heptakis(6-methoxyethylamine-6-deoxy)-beta-cyclodextrin [beta-CD-OMe (VII)] performs exceptionally well for the enantiomeric resolution of NSAIDs: indoprofen and fenoprofen (Rs = 11 and 14, respectively). In addition, baseline enantiomeric separation of a mixture of six pairs of PPAHs was achieved in under 30 min. Compared to other cationic beta-cyclodextrins reported in the literature, the beta-CD-OMe (VII) showed improved selectivity for both classes of the aforementioned anionic racemates.  相似文献   
175.
Low and high consistent pro-socials and pro-selfs were primed with neutral, morality, or might concepts in mixed-motive situations. The authors expected participants' social value orientation to influence cooperative behavior among (a) high consistent individuals in all prime conditions and (b) low consistent individuals in the neutral prime condition only. The authors also expected the primes to influence cooperative behavior more among low than high consistent individuals. Four experiments using supraliminal (Experiments 1, 2, and 4) or subliminal (Experiment 3) priming and 2-person (Experiments 1-3) or N-person (Experiment 4) social dilemmas partially supported these initial predictions. One intriguing exception was that morality primes reduced cooperation among high consistent pro-selfs. Experiments 2-4 allowed testing for the potential role of expectations in shaping participants' cooperative behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
176.
本文主要研究在超薄埋氧SOI器件内,位于硅薄膜内的单点缺陷造成的随机电报噪声(RTN)。通过低频噪声测试和时域测试,硅薄膜内单点缺陷RTN得到了识别和分析。RTN的相对幅值dID/ID与前栅、背栅、源漏电压的关系得到了具体的分析。实验结果显示,交换源漏电极位置时,不同单点缺陷的dID/ID与VDS的相关性会呈现一致性或者非一致性。这是由于单点缺陷在源漏方向的位置不同所致。文中还做了进一步的仿真研究,对这一点进行验证和解释。  相似文献   
177.
We describe the design of a knowledge-building environment and examine the role of knowledge-building portfolios in characterizing and scaffolding collaborative inquiry. Our goal is to examine collaborative knowledge building in the context of exploring the alignment of learning, collaboration, and assessment in computer forums. The key design principle involved turning over epistemic agency to students; guided by several knowledge-building principles, they were asked to identify clusters of computer notes that indicated knowledge-building episodes in the computer discourse. Three classes of 9th grade students in Hong Kong used Knowledge Forum in several conditions: Knowledge Forum only, Knowledge Forum with portfolios, and Knowledge Forum with portfolios and principles. Results showed: (1) Students working on portfolios guided knowledge-building principles showed deeper inquiry and more conceptual understanding than their counterpart (2) Students' knowledge-building discourse, reflected in portfolio scores, contributed to their domain understanding; and (3) Knowledge-building portfolios helped to assess and foster collective knowledge advances: A portfolio with multiple contributions from students is a group accomplishment that captures the distributed and progressive nature of knowledge building. Students extended their collective understanding by analyzing the discourse, and the portfolio scaffolded the complex interactions between individual and collective knowledge advancements. An erratum to this article is available at .  相似文献   
178.
Large spatial-scale atmospheric aerosol characterization is commonly accomplished from high-speed aircraft platforms using subisokinetic sampling. The aspiration efficiencies in these inlets are commonly determined from the empirical correlation of Belyaev and Levin [1974. Techniques for collection of representative aerosol samples. Journal of Aerosol Science, 5, 325–338] (B&L), though the correlation was obtained from experiments under conditions very different from those encountered during high-speed aircraft sampling. Aircraft inlets are generally thick-walled, often have a blunt-body downstream, operate at a large freestream to sampling velocity ratio, and under conditions of low ambient pressures. The dependence of sampling characteristics on these parameters is studied using computational fluid dynamics (CFD) modeling. The CFD calculations show that the anisokinetic inlet sampling characteristics are strongly influenced by the operating conditions and sampler geometry, especially the presence of an aft blunt body. It is observed that these dependencies are not accurately captured by the existing correlations. The presence of even a moderately sized blunt-body aft of a sampling inlet can greatly influence the sampling characteristics of a straight tube inlet. A new correlation is derived based on the CFD simulation results, and this correlation is seen to greatly improve prediction of inlet sampling characteristics considering their geometries.  相似文献   
179.
Field data obtained in 2003–2004 are used to describe the influence of atmospheric and riverine forcing on the thermal history of fjord-type lakes using Quesnel Lake, British Columbia, Canada as an example. Typical of fjord-type lakes, Quesnel Lake is narrow, long (> 100 km total thalweg), multi-armed (three arms of comparable size), deep (maximum depth > 500 m), and has multiple basins separated by sills. The lake's annual thermal history responds to the joint forcing of surface heat exchange, river inputs, and wind stress. The lake's annual heat budget is dominated by surface radiative fluxes, and riverine input of heat is insignificant in this medium residence time lake (10 years). Despite being insignificant to the annual heat budget, the three major rivers that feed the three arms of the lake contribute to the overall lake circulation pattern. Since these rivers have differing salinities, it is possible to identify, using temperature/salinity correlation diagrams, patterns of riverine circulation interflowing in the lake. Data from a 1-year thermistor-chain record suggests exchange between surface and intermediate waters occurs twice annually, but deep-waters below 150–250 m are mainly renewed during autumn, by strong and episodic atmospheric forcing. This is because wind-forced turbulent diffusion and gravitational convection triggered by wind forced displacement of isotherms (initiating thermobaric instability) are required for full overturn and deep-water renewal.  相似文献   
180.
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