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   26859篇
  免费   1117篇
  国内免费   11篇
  2020年   309篇
  2019年   418篇
  2018年   569篇
  2017年   596篇
  2016年   605篇
  2015年   483篇
  2014年   520篇
  2013年   2273篇
  2012年   886篇
  2011年   939篇
  2010年   571篇
  2009年   538篇
  2008年   734篇
  2007年   780篇
  2006年   667篇
  2005年   608篇
  2004年   573篇
  2003年   566篇
  2002年   572篇
  2001年   812篇
  2000年   758篇
  1999年   585篇
  1998年   280篇
  1997年   248篇
  1996年   275篇
  1994年   238篇
  1992年   488篇
  1991年   480篇
  1990年   466篇
  1989年   422篇
  1988年   445篇
  1987年   404篇
  1986年   411篇
  1985年   427篇
  1984年   340篇
  1983年   288篇
  1982年   246篇
  1979年   383篇
  1978年   289篇
  1977年   251篇
  1975年   308篇
  1974年   374篇
  1973年   391篇
  1972年   306篇
  1971年   301篇
  1970年   298篇
  1969年   257篇
  1968年   354篇
  1967年   313篇
  1966年   287篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
A multiple probe across behaviors design, replicated across participants, assessed the effectiveness of constant time delay in teaching appropriate peer reinforcement and grocery words to 3 elementary students with moderate intellectual disabilities. Additionally, pretests and posttests assessed the acquisition of the participants' observational learning (acquisition of peers' grocery words) and instructive feedback (related information supplied by the teacher in the consequent event). Results indicate that the participants learned (a) how to appropriately reinforce peers, (b) to read their grocery words, (c) some of the targeted stimuli of their peers, and (d) much of the instructive feedback that was associated with each of the grocery words. Maintenance data indicate that the participants maintained their target grocery words at high levels of accuracy.  相似文献   
952.
Students in a residential special school for children with emotional and behavioral disorders participated in a study designed to reduce their levels of inappropriate behavior. The residential care staff rated the students' behavioral problems and their class teachers rated their overt self-esteem pre and post intervention. In addition, the students completed self-ratings of their self-esteem. The students were divided into two groups, experimental and control. A multiple baseline across behaviors design was used to assess behavioral changes in the experimental group. Both groups received tangible rewards to the same level but only the experimental group received them contingent upon behaving appropriately. Results showed that the experimental group students made substantial reductions in their levels of inappropriate behavior, which were maintained at a three-month followup. Also, ratings of their behavioral problems by residential child care staff suggested that this improvement in behavior had generalized beyond the classroom to the residential setting. However, no significant differences were found between the pre- and post-intervention ratings of their self-esteem or teacher ratings of their overt self-esteem.  相似文献   
953.
The National Conference of Catholic Bishops has argued for significant government involvement in health care in order to assure respect for what they regard as the right to health care. Critics charge that the bishops are wrong because health care is not a right. In this article, it is argued that these critics are correct in their claim that health care is not a right. However, it is also argued that the premise that health care is not a right does not imply that the market is the most equitable and just system for providing health care. Natural law arguments in the tradition of Roman Catholic social teaching lead to the conclusion that a just and prosperous society has a moral obligation to provide health care even if there is no such right. Further, there are strong moral grounds for concluding that the bishops are correct in their claim that health care ought not to be considered a market commodity. It is argued that if health care ought not to be considered a commodity, then national health insurance is the best available alternative for fulfilling the social obligation to distribute health care resources justly and fairly at this time in American history. The bishops' case for government involvement can be made on the strength of the Catholic tradition in theological argumentation, independent of the claim that health care is a right.  相似文献   
954.
955.
Individual and institutional conflict of interests in biomedical research have becomes matters of increasing concern in recent years. In the United States, the growth in relationships — sponsored research agreements, consultancies, memberships on boards, licensing agreements, and equity ownership — between for-profit corporations and research universities and their scientists has made the problem of conflicts, particularly financial conflicts, more acute. Conflicts can interfere with or compromise important principles and obligations of researchers and their institutions, e.g., adherence to accepted research norms, duty of care to patients, and open exchange of information. Disclosure is a key component of a successful conflict policy. Commitments which conflict with a faculty member's primary obligations to teaching, research, administrative responsibilities, or patient care also need attention. Institutional conflict of interests present different problems, some of which are discussed in an analysis of an actual problem posed by two proposed clinical trials. This paper is adapted from a lecture presented to a Symposium on Scientific Integrity, Warsaw, Poland, 23 November 1995. Daniel Steiner was Vice-President and General Counsel of Harvard University (1972–92) and in that capacity became familiar with conflict of interest issues. He is currently Counsel to the Boston law firm. Ropes and Gray, and is Adjunct Lecturer in Public Policy at the John F. Kennedy School of Government. Harvard University.  相似文献   
956.
The availability of the UNIX operating system on large supercomputers has greatly simplified the importation of research software from workstations and minicomputers. Supercomputers generally offer much greater memory and storage than do smaller machines, which may make their use mandatory for some large applications. Realization of the full performance offered by vectorizing supercomputers such as the Cray C90 sometimes requires modification of existing code. The use of high-level interpreters for the development of applications is recommended, to minimize the amount of compiled code that must be optimized.  相似文献   
957.
958.
959.
Ten subjects served as their own controls in two conditions of continuous, centrifugally produced hypergravity (+2 Gz) and a 1-G control condition. Before and after exposure, open-loop measures were obtained of (1) motor control, (2) visual localization, and (3) hand-eye coordination. During exposure in the visual feedback/hypergravity condition, subjects received terminal visual error-corrective feedback from their target pointing, and in the no-visual feedback/hypergravity condition they pointed open loop. As expected, the motor control measures for both experimental conditions revealed very short lived underreaching (the muscle-loading effect) at the outset of hypergravity and an equally transient negative aftereffect on returning to 1 G. The substantial (approximately 17°) initial elevator illusion experienced in both hypergravity conditions declined over the course of the exposure period, whether or not visual feedback was provided. This effect was tentatively attributed to habituation of the otoliths. Visual feedback produced a smaller additional decrement and a postexposure negative aftereffect, possible evidence for visual recalibration. Surprisingly, the target-pointing error made during hypergravity in the no-visual-feedback condition was substantially less than that predicted by subjects’ elevator illusion. This finding calls into question the neural outflow model as a complete explanation of this illusion.  相似文献   
960.
In January 1996, the American Board of Genetic Counseling (ABGC) adopted 27 practice-based competencies as a standard for assessing the training of graduate students in genetic counseling. These competencies were identified and refined through a collective, narrative process that took place from January through November 1994, and included directors of graduate programs in genetic counseling, ABGC board members and expert consultants. These competencies now form the basis of the document Requirements for Graduate Programs in Genetic Counseling Seeking Accreditation by the American Board of Genetic Counseling (American Board of Genetic Counseling, 1996). The competencies are organized into four domains and are presented and discussed in this article.The Consortium includes Directors of established graduate programs in genetic counseling and members of the ABGC Board of Directors who participated in the Consensus Development Conference held in January, 1994: Diane Baker (University of Michigan/ABGC); Bonnie Baty (ABGC); Joan Burns (University of Wisconsin); Debra Collins (ABGC); Virginia Corson (ABGC); Beth Fine (Northwestern University/ABGC); Elizabeth Gettig (University of Pittsburgh); Verle Headings (Howard University); Jacqueline Hecht (University of Texas); Carl Huether (University of Cincinnati); Bonnie LeRoy (University of Minnesota); Joan Marks (Sarah Lawrence College); Anne Matthews (University of Colorado); Roberta Palmour (McGill University); Lorna Phelps (Medical College of Virginia); Kimberly Quaid (Indiana University); Joan Scott (ABGC); Ann Smith (ABGC); Helen Travers (ABGC); Judith Tsipis (Brandeis University); Ann Walker (University of California-Irvine/ABGC); Jon Weil (University of California-Berkeley); S. Robert Young (University of South Carolina); Randi Zinberg (Mount Sinai School of Medicine, New York).  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