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871.
Schneider C 《Science and engineering ethics》2000,6(1):49-56
After summarising three recent case histories of alleged scientific misconduct in Germany, the efforts of the Deutsche Forschungsgemeinschaft (German Research Council) and the Hochschulrektorenkonferenz (German Rectors' Conference) to promote academic and procedural safeguards in favour of professional self-regulation in science and scholarship are described in outline. 相似文献
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English contains many nominals that would be absent in Chinese because Chinese makes greater use of zero anaphora, which is an empty grammatical slot in a sentence standing for a previously mentioned referent. Native Chinese and native English speakers were compared in comprehending modified English passages from a standardized reading test with nominals deleted that would be absent in Chinese. In three experiments, Chinese speakers showed superior comprehension as measured by objective multiple-choice questions in this case, but not when no words were deleted or when nominals were deleted that would not be absent in Chinese. These results imply that native Chinese speakers develop reference tracking strategies that they transfer to comprehending English.This research was supported in part by United States Army Research Institute Contracts MDA903-93-K-0010, DASW01-96-K-0010, DASW01-99-K-0002, and DASW01-03-K-0002 to the University of Colorado (Alice Healy, Principal Investigator).We thank Lyle Bourne and Barbara Fox for stimulating discussions about this research. We are also grateful to the Institute of Cognitive Science at the University of Colorado for their support of this research.Experiments 1 and 2 were reported at the International Conference on Functional Approaches to Grammar, Albuquerque, NM, July 25, 1995, and at the 37th Annual Meeting of the Psychonomic Society, Chicago, IL, November 3, 1996, and all three experiments were reported at the 2001 American Association for Applied Linguistics conference, St. Louis, MO, February 24, 2001. 相似文献
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Nicotinic cholinergic synaptic mechanisms in the ventral tegmental area contribute to nicotine addiction 总被引:16,自引:0,他引:16
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Pidoplichko VI Noguchi J Areola OO Liang Y Peterson J Zhang T Dani JA 《Learning & memory (Cold Spring Harbor, N.Y.)》2004,11(1):60-69
Tobacco use is a major health problem that is estimated to cause 4 million deaths a year worldwide. Nicotine is the main addictive component of tobacco. It acts as an agonist to activate and desensitize nicotinic acetylcholine receptors (nAChRs). A component of nicotine's addictive power is attributable to actions on the mesolimbic dopaminergic system, which serves a fundamental role in the acquisition of behaviors that are inappropriately reinforced by addictive drugs. Here we show that nicotine, in the same concentration and time ranges as obtained from tobacco, has three main actions that regulate the activity of midbrain dopamine (DA) neurons. Nicotine first activates and then desensitizes nAChRs on the DA neurons. This process directly excites the DA neurons for a short period of time before the nAChRs desensitize. Nicotine also enhances glutamatergic excitation and decreases GABAergic inhibition onto DA neurons. These events increase the probability for synaptic plasticity, such as long-term potentiation. The short-lived direct excitation of the DA neurons coupled with the enhanced glutamatergic afferent activity provides the presynaptic and postsynaptic coincidence necessary to initiate synaptic potentiation. In total, these synaptic events lead to a relatively long-lasting heightened activity of midbrain DA neurons. Consistent with other summarized studies, this work indicates that the synaptic changes normally associated with learning and memory can be influenced and commandeered during the nicotine addiction process. 相似文献
877.
探讨阅读文章难易程度与文章字词和内容在小学生篇章阅读迁移中的作用。被试分为阅读水平高、低两组。采用个别方式施测,以阅读时间和阅读准确性为阅读迁移的指标。结果表明,低水平组被试的篇章阅读迁移主要依赖词汇表征;高水平组被试的篇章阅读迁移主要依赖内容表征,换言之,容易文章主要以内容表征进行迁移;困难文章主要以词汇表征进行迁移。 相似文献
878.
Previous studies have shown that an aphasic patient (AB) with a semantic short-term memory deficit (STM) had difficulties comprehending and producing sentences with structures that demanded the simultaneous retention of several individual word meanings (Martin & Freedman, 2001a, 2001b; Martin & Romani, 1994; Martin, Shelton, & Yaffee, 1994). The present study provides a replication of these findings with an additional case (ML) who shows a striking dissociation between preserved semantic knowledge and disrupted semantic STM. ML performed poorly on comprehension tasks for sentences that required the retention of single word meanings across several intervening words. In contrast, he did not show an effect of intervening words on processing grammatical relations. ML had difficulty producing adjective-noun phrases, though able to produce the individual nouns and adjectives. These findings support the contention that there is a semantic retention capacity, involved in both comprehension and production, that is separate from semantic knowledge representations. 相似文献
879.
The full information item factor (FIIF) model is very useful for analyzing relations of dichotomous variables. In this article, we present a feasible procedure to assess local influence of minor perturbations for identifying influence aspects of the FIIF model. The development is based on a Q-displacement function which is closely related with the Monte Carlo EM algorithm in the ML estimation. In the E-step of this algorithm, the conditional expectations are approximated by sample means of observations simulated by the Gibbs sampler from the appropriate conditional distributions. It turns out that these observations can be utilized for computing the building blocks of the proposed diagnostic measures. The diagnoses are based on the conformal normal curvature that can be computed easily. A number of interesting perturbation schemes are considered. The methodology is illustrated with two real examples.The research is fully supported by a grant (CUHK 4356/00H) from the Research Grant Council of the Hong Kong Special Administration Region. The authors are thankful to the Editor, Associate Editor, anonymous reviewers, and W.Y. Poon for valuable comments for improving the paper, and to ICPSR and the relevant founding agency for allowing us to use of their data. The assistance of Michael Leung and Esther Tam is gratefully acknowledged. 相似文献
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