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   20604篇
  免费   1820篇
  国内免费   1362篇
  23786篇
  2024年   43篇
  2023年   364篇
  2022年   317篇
  2021年   406篇
  2020年   790篇
  2019年   802篇
  2018年   739篇
  2017年   908篇
  2016年   921篇
  2015年   576篇
  2014年   778篇
  2013年   2365篇
  2012年   485篇
  2011年   602篇
  2010年   510篇
  2009年   725篇
  2008年   946篇
  2007年   966篇
  2006年   894篇
  2005年   778篇
  2004年   666篇
  2003年   564篇
  2002年   532篇
  2001年   356篇
  2000年   328篇
  1999年   286篇
  1998年   209篇
  1997年   184篇
  1996年   150篇
  1995年   142篇
  1994年   138篇
  1993年   101篇
  1992年   78篇
  1991年   68篇
  1990年   63篇
  1989年   41篇
  1988年   51篇
  1985年   378篇
  1984年   428篇
  1983年   348篇
  1982年   455篇
  1981年   447篇
  1980年   451篇
  1979年   399篇
  1978年   448篇
  1977年   355篇
  1976年   355篇
  1975年   272篇
  1974年   278篇
  1973年   236篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
221.
To examine to what degree argumentation skills are mastered by pupils who attend the vocational, general and academic streams in Dutch secondary education various subtests were constructed. The theoretical study of argumentation as exposed by Van Eemeren and Grootendorst was the basis for this test construction. In this article tests for the identification of singular, multiple and subordinate argumentation are described. Also an account is given of a pretest of these three subtests.  相似文献   
222.
The issues involved in decision making about the aggressiveness of future medical care for older persons are explored. They are related to population trends, the heterogeneity of older persons and a variety of factors involved in individual preferences. Case studies are presented to illustrate these points, as well as a review of pertinent literature. The argument is offered that, considering these many factors, a system of flexible, individualized care by informed patient preference, is more rational than the rationing of technological services by age.  相似文献   
223.
This paper examines the ethical issues of conflict of interest raised by the burgeoning development of physician involvement in for-profit entrepreneurial activities outside their practice. After documenting the nature and extent of these activities, and their potential for conflicts of interest, the paper assesses the major arguments for and against physicians' referral of patients to facilities they own or in which they invest. The paper concludes that an outright ban on such activity seems ethically warranted.  相似文献   
224.
The paper is an attempt to review the basis for the claim that physicians have a professional obligation to treat AIDS patients. Considered are the historical record, two professional codes of ethics, and several recent articles. The paper concludes that the arguments considered, which attempt to support the claim that physicians have an obligation to treat, fail. It is suggested, rather, that common humanity, which physicians share with those who suffer from AIDS, ought to be the basis for engaging in the care of AIDS patients.  相似文献   
225.
Philip Hefzer 《Zygon》1993,28(1):77-101
Abstract. The paper consists of an argument that goes as follows. Symbols and their elaboration into myths constitute Homo sapiens 's most primitive reading of the world and the relation of humans to that world. They are, in other words, primordial units of cultural information, emerging very early in human history, representing a significant achievement in the evolution of human self-consciousness and reflection. The classic myths of Fall and Original Sin, as well as the doctrines to which they gave rise, are further interpretations of this primordial information. The doctrinal traditions of the first four centuries of Christianity are surveyed. Three sets of data as interpreted by the biological sciences are offered as resources for understanding the biogenetic grounds of the experience that the symbols, myths, and doctrines of Fall and Original Sin seek to interpret. The conclusions to be drawn are that (1) the symbolic material is indeed commensurate with the scientific understandings, and (2) the scientific interpretations deepen our understanding of the symbols, while (3) the conversation between the symbols and the science once again raises certain perennial questions about human existence.  相似文献   
226.
人类颜色视觉的计算理论   总被引:2,自引:0,他引:2  
该文有机地结合了计算视觉理论和生态学视觉理论,指出颜色信息处理的根本任务是检测环境中的光不变量。在此基础上,作者提出了颜色视觉的计算理论以及计算理论本身的生物学标准。初级视觉计算是典型的不适定问题,动物的视觉系统则利用视环境中存在的条件将该不适定问题转化为定解问题。本文引入颜色视觉计算的免要条件,客观性约束,以及颜色认知的神经表象,证明了上述约束下颜色算法的存在性。本文给出了构造颜色知觉的基本假设。同时,该文还讨论了与上述问题密切相关的几个基本问题:神经表象的完备性,主观色觉的客观性,明度知觉和颜色知觉的统一,人类主观色觉的实现方式。  相似文献   
227.
228.
229.
230.
驾驶员心理品质检测中的杆型人形图法   总被引:1,自引:0,他引:1  
在汽车驾驶员心理品质检测研究中,我们根据数学中的多变量图分析方法,并汲取简笔画的优点,用19个人形图变量代表检测所得的17种心理品质数据,来具体、形象地再现每个驾驶员心理品质变量的整体关系。这对于检测结果的分类或进行系统化分析具有重要的实用意义。  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