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   6899篇
  免费   351篇
  国内免费   1篇
  7251篇
  2024年   16篇
  2023年   73篇
  2022年   67篇
  2021年   122篇
  2020年   151篇
  2019年   210篇
  2018年   266篇
  2017年   266篇
  2016年   301篇
  2015年   216篇
  2014年   223篇
  2013年   823篇
  2012年   387篇
  2011年   405篇
  2010年   236篇
  2009年   226篇
  2008年   335篇
  2007年   283篇
  2006年   236篇
  2005年   244篇
  2004年   241篇
  2003年   244篇
  2002年   177篇
  2001年   122篇
  2000年   135篇
  1999年   92篇
  1998年   72篇
  1997年   61篇
  1996年   50篇
  1995年   43篇
  1994年   31篇
  1993年   37篇
  1992年   64篇
  1991年   58篇
  1990年   80篇
  1989年   60篇
  1988年   63篇
  1987年   39篇
  1986年   51篇
  1985年   47篇
  1984年   43篇
  1983年   39篇
  1982年   30篇
  1981年   19篇
  1980年   17篇
  1979年   25篇
  1978年   26篇
  1977年   20篇
  1974年   15篇
  1972年   14篇
排序方式: 共有7251条查询结果,搜索用时 7 毫秒
71.
Summary We are less prone today than in Köhler's time to believe in a unified science. The Gestalt program could therefore safely abandon the psychophysical isomorphism heuristic if it wished to. Indeterminacy of the heuristic might be a reason for doing so. The determination of the components involved in the isomorphism of the visual field as well as the electrocortical events would have to occur simultaneously. In the Gestalt program, however, components are determined by their position in the whole. They can therefore not be compared in different contexts, so no independent test of a candidate heuristic is possible.  相似文献   
72.
Are women in a female-dominated profession more successfully able to combine work and family obligations than women in a male-dominated profession? To explore this question, a comparison was made between the family status and careers of 747 women librarians (a female-dominated profession) and those of 449 women MBAs (a male-dominated profession). It was expected that the librarians would marry earlier and have more children. This general prediction was not supported. Over half of both groups of women were married, and after controlling for age, there were no differences in number of children. However, many women without children in both groups reported that they would like to be mothers. This disparity between wanting children and not having them was more common for women MBAs than women MLSs. MBAs and librarians were about equally likely to have had job interruptions, but librarians were more likely to have worked part-time. Reasons for an interruption to full-time work were as likely to be for problems finding (full-time) work as for family responsibilities. Librarians' salaries were much lower, but job interruptions and part-time work had a more negative effect on the salaries of women in business. In sum, the data suggest that many of the women surveyed have not combined motherhood with a professional career and that it is probably somewhat more difficult to combine a family with a career in business than with a career in library science.  相似文献   
73.
74.
Review     
  相似文献   
75.
Saunders BA  van Brakel J 《The Behavioral and brain sciences》1997,20(2):167-79; discussion 179-228
In this target article the following hypotheses are discussed: (1) Colour is autonomous: a perceptuolinguistic and behavioural universal. (2) It is completely described by three independent attributes: hue, brightness, and saturation: (3) Phenomenologically and psychophysically there are four unique hues: red, green, blue, and yellow; (4) The unique hues are underpinned by two opponent psychophysical and/or neuronal channels: red/green, blue/yellow. The relevant literature is reviewed. We conclude: (i) Psychophysics and neurophysiology fail to set nontrivial constraints on colour categorization. (ii) Linguistic evidence provides no grounds for the universality of basic colour categories. (iii) Neither the opponent hues red/green, blue/yellow nor hue, brightness, and saturation are intrinsic to a universal concept of colour. (iv) Colour is not autonomous.  相似文献   
76.
Molecular sequence data, made available in the last 15 years or so, have led to the classification of living cells into three phylogenetic domains: Bacteria, Archaea, and Eucarya. All the organisms that have been tested belonging to either domain were capable of mounting a stress response with essentially the same characteristics, regardless of the stressor. The protagonists in the cell's stress response are the stress genes and their protein products. Some of the latter are molecular chaperones. Under physiological conditions, these chaperones aid other cellular proteins to fold properly and achieve a native -functional- configuration, and to translocate from the place of synthesis to the cell's locale in which they will operate. In a stressed cell, the stress proteins that are chaperones protect other molecules from denaturation and help those partially damaged to regain a functional configuration. Thus, cell death is avoided and recovery is enhanced. The study of stress genes and proteins has progressed considerably in organisms belonging to the domains Bacteria and Eucarya. Less is known about the archaeal stress genes. Here, research with an organism from the Archaea is discussed, focusing on the stress genes of the hsp70 (dnaK) locus. Future perspectives for basic and applied research within the health sciences and biotechnology industries are presented.  相似文献   
77.
This study was designed to explore the limitations of tau (τ) as an explanatory construct for the timing of interceptive action. This was achieved by examining the effects of environmental structure and binocular vision on the timing of the grasp in a simple one-handed catch. In two experiments, subjects were required to catch luminous balls of different diameters (4, 6, 8 and 10 cm) in a completely darkened room. In the first experiment the influence of the presence vs. absence of an environmental background structure (both under monocular viewing) was tested, and in the second experiment the influence of monocular vs. binocular vision was examined. It was found that irrespective of the presence of environmental structure, an effect of ball size occurred in the monocular viewing conditions. That is, in monocular viewing conditions the grasp was initiated and completed earlier for the larger balls as compared to the smaller ones, while in the binocular viewing condition subjects behaved in accordance with a constant time to contact strategy: no effects of ball size were found. It is concluded that under binocular viewing a binocular information source is used, while in the monocular viewing condition a lower order information source like image size or image velocity is probably involved.  相似文献   
78.
This article describes the development and validation of the McMaster Clinical Rating Scale (MCRS). The MCRS is a 7-item scale designed to be completed by a trained rater after completion of an in-depth interview of the family. We present data from four new studies and review previously published articles concerning the reliability, validity, and clinical utility of the MCRS. Adequate interrater reliability and rater stability were obtained. The MCRS was found to correlate significantly with the self-report Family Assessment Device and to discriminate between families in different phases of a depressive disorder.  相似文献   
79.
Ren van Woudenberg 《Ratio》1995,8(2):170-188
This paper is a contribution to the debate on epistemic foundationalism. Section I expounds and criticises Hans Albert's critical rationalist antifoundationalism position. Section I1 discusses Karl-Otto Apel's ‘transcendental pragmatic’ argument for ultimate epistemic foundations. Section III suggests how the latter argument can be restated so as to avoid ambiguity and yield a plausible case for epistemic foundationalism.  相似文献   
80.
W. M. de Muynck 《Synthese》1995,102(2):293-318
The axiomatic approaches of quantum mechanics and relativity theory are compared with approaches in which the theories are thought to describe readings of certain measurement operations. The usual axioms are shown to correspond with classes of ideal measurements. The necessity is discussed of generalizing the formalisms of both quantum mechanics and relativity theory so as to encompass more realistic nonideal measurements. It is argued that this generalization favours an empiricist interpretation of the mathematical formalisms over a realist one.  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