首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   68篇
  免费   0篇
  国内免费   3篇
化学   35篇
晶体学   1篇
数学   13篇
物理学   22篇
  2023年   2篇
  2015年   1篇
  2014年   1篇
  2013年   3篇
  2012年   4篇
  2011年   4篇
  2010年   4篇
  2008年   4篇
  2007年   4篇
  2005年   5篇
  2004年   1篇
  2003年   3篇
  2002年   2篇
  2001年   7篇
  2000年   3篇
  1999年   5篇
  1998年   2篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1989年   1篇
  1988年   1篇
  1986年   2篇
  1985年   3篇
  1983年   1篇
  1980年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有71条查询结果,搜索用时 15 毫秒
1.
Prior research has argued that cognitive style can have a significant impact on group decision making. In addition, several scholars have proposed that cognitive style can play a key role in the design and use of group decision support systems. However, cognitive style has not received a great deal of attention in the problem structuring methods (PSMs) community. This is surprising, given that PSMs are specifically developed to support a group in their decision making. The purpose of this paper is thus to examine the significance of cognitive style within PSMs. The paper identifies and explores the role of four different cognitive style functions in problem structuring interventions. This analysis is carried out by focusing on the different tasks embedded within a group process supported by PSMs. Implications for the research and practice of PSMs are then discussed.  相似文献   
2.
From a sample of 1172 +/- 61 D(+)-->pi(-)pi(+)pi(+) decays, we find gamma(D(+)-->pi(-)pi(+)pi(+))/gamma(D(+)-->K-pi(+)pi(+)) = 0.0311 +/- 0.0018(+0.0016)(-0.0026). Using a coherent amplitude analysis to fit the Dalitz plot of these decays, we find strong evidence that a scalar resonance of mass 478(+24)(-23) +/- 17 MeV/c(2) and width 324(+42)(-40) +/- 21 MeV/c(2) accounts for approximately half of all decays.  相似文献   
3.
Chameleon sequences are amino acid sequences found in several distinct configurations in experiment. They challenge our understanding of the link between sequence and structure, and provide insight into structural competition in proteins. Here, we study the energy landscapes for three such sequences, and interrogate how pulling and twisting forces impact the available structural ensembles. Chameleon sequences do not necessarily exhibit multiple structural ensembles on a multifunnel energy landscape when we consider them in isolation. The application of even small forces leads to drastic changes in the energy landscapes. For pulling forces, we observe transitions from helical to extended structures in a very small span of forces. For twisting forces, the picture is much more complex, and highly dependent on the magnitude and handedness of the applied force as well as the reference angle for the twist. Depending on these parameters, more complex and more simplistic energy landscapes are observed alongside more and less diverse structural ensembles. The impact of even small forces is significant, confirming their likely role in folding events. In addition, small forces exerted by the remaining scaffold of a protein may be sufficient to lead to the adoption of a specific structural ensemble by a chameleon sequence.  相似文献   
4.
A survey of strategic planning managers was considered to identify the current practice of developing corporate visions, with a particular focus on how the vision was developed. The paper begins with a brief review of the literature concerning organisational visions and their development. The issues addressed by the survey and the research methodology are then described, and the results of the research presented. The paper ends with a discussion of the findings of the survey, and suggests ways of progressing research in this area.  相似文献   
5.
Simple (equally weighted) moving averages are frequently used to estimate the current level of a time series, with this value being projected as a forecast for future observations. A key measure of the effectiveness of the method is the sampling error of the estimator, which this paper defines in terms of characteristics of the data. This enables the optimal length of the average for any steady state model to be established and the lead time forecast error derived. A comparison of the performance of a simple moving average (SMA) with an exponentially weighted moving average (EWMA) is made. It is shown that, for a steady state model, the variance of the forecast error is typically less than 3% higher than the appropriate EWMA. This relatively small difference may explain the inconclusive results from the empirical studies about the relative predictive performance of the two methods.  相似文献   
6.
A new block elimination method for bordered systems is proposedand its numerical properties are analysed. In the case wherethe leading principal block is ill-conditioned or singular andthe method becomes unstable a perturbation approach is usedto enhance the stability. Results of experiments performed onthe SGI Power Challenge 8000 and on the Cray J-9x illustratethe performance of the new algorithm and compare it with thecurrent best approach. It is shown that the new method worksfaster while preserving stability.  相似文献   
7.
The purpose of this paper is to propose and explore a general framework within which a wide variety of model construction techniques from contemporary set theory can be subsumed. Taking our inspiration from presheaf constructions in category theory and Boolean ultrapowers, we will show that generic extensions, ultrapowers, extenders and generic ultrapowers can be construed as examples of a single model construction technique. In particular, we will show that Łoś's theorem can be construed as a specific case of Cohen's truth lemma, and we isolate the weakest conditions a filter must satisfy in order for the truth lemma to work.  相似文献   
8.
Studies in which BABAR data have shown evidence for mixing in the neutral charm meson system are presented. A new measurement of the lifetime difference parameter ycp = (1.16±0.22±0.18)% is described. Results are also presented from a systematic study of DK and D*K invariant mass distributions from a 470 fb^-1 sample of asymmetric e^+e^- interactions recorded by the BABAR detector at the PEP-Ⅱ storage rings. A new charmed-strange meson has been observed with mass [3044 ± 8stat (-5^+30 )syst] MeV/c^2 and width [239± 35stat (-42^+46)syst]MeV/c^2.  相似文献   
9.
10.
The main scope of the article is to investigate the effect of ferrite cores gap in a universal matchbox on an ultrasonic vibrating system. A gapped transformer mechanism in a universal matchbox has been thoroughly studied. Characteristics of an ultrasonic vibrating system have been recorded such as mechanical vibrations, inductance, resonant frequencies, current and voltage levels as the gap of ferrite cores gradually increases. In addition, the phase difference between the supplied voltage and the current is also computed and displayed in a Lissajous curve in order to determine the optimal gap between two ferrite cores in the universal matchbox. Explanations supplement the experiment results.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号