全文获取类型
收费全文 | 4396篇 |
免费 | 2235篇 |
国内免费 | 37篇 |
专业分类
6668篇 |
出版年
2024年 | 6篇 |
2023年 | 25篇 |
2022年 | 30篇 |
2021年 | 150篇 |
2020年 | 214篇 |
2019年 | 600篇 |
2018年 | 506篇 |
2017年 | 601篇 |
2016年 | 593篇 |
2015年 | 495篇 |
2014年 | 462篇 |
2013年 | 634篇 |
2012年 | 287篇 |
2011年 | 304篇 |
2010年 | 222篇 |
2009年 | 215篇 |
2008年 | 153篇 |
2007年 | 173篇 |
2006年 | 183篇 |
2005年 | 159篇 |
2004年 | 106篇 |
2003年 | 104篇 |
2002年 | 97篇 |
2001年 | 104篇 |
2000年 | 78篇 |
1999年 | 47篇 |
1998年 | 20篇 |
1997年 | 7篇 |
1996年 | 15篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
排序方式: 共有6668条查询结果,搜索用时 0 毫秒
11.
This paper describes the basic elements of practice development and management within the academic medical setting. These include assessment of the market environment, both in the community and within the medical setting, product development, marketing, budget basics, quality, managed care negotiations, and finding time to do research in a financially-driven health care system. 相似文献
12.
We examined the effect of self-correction on the acquisition, maintenance, and generalization of written spelling of elementary school students attending an after-school clinic. Six students registered for remedial tutoring participated. During self-correction, students initially learned four proofreading marks and a procedure for using them that were subsequently applied as the students compared their spelling to a model. Results showed a functional effect between self-correction and improved student performance on target words. Using the self-correction procedure, the students spelled at least 98% of the target words accurately, maintained at least 85% of the correctly spelled words, and generalized at least 70% of the words at home, in context, and with word variations. Questionnaires administered to the students, their parents, and teachers indicated that students preferred self-correction. Parents noticed academic improvements in their child's spelling performance as well as positive changes in attitude toward school. Most teachers did not notice changes in spelling performance or attitude. 相似文献
13.
Various complexities that arise in the application of legal and/or clinical criteria to the actual assessment of competence/capacity are discussed, and a particular way of understanding the nature of such criteria is recommended. 相似文献
14.
15.
Human Signal-detection Performance: Effects Of Signal Presentation Probabilities And Reinforcer Distributions 总被引:2,自引:2,他引:0 下载免费PDF全文
University students participated in one of four standard two-choice signal-detection experiments in which signal presentation probability was varied and the reinforcement distribution was held constant and equal. In Experiments 1, 3 and 4, subjects' performance showed a systematic response bias for reporting the stimulus presented least often. Experiments 1 and 4 showed that this effect was reliable with extended training and monetary, rather than point, reinforcement. In Experiment 2, all correct responses were signaled in some way, and this produced the opposite relationship between signal presentation probability and response bias. Experiments 1 and 3 found that explicitly deducting money (intended as punishment) for equal numbers of incorrect responses on each alternative, or varying the obtained overall rate of reinforcement, produced no clear change in response bias. The bias, shown by humans, for reporting the stimulus presented least often remains a challenge for theories of stimulus detection. 相似文献
16.
Detecting a nonevent: Delayed presence-versus-absence discrimination in pigeons 总被引:1,自引:1,他引:0 下载免费PDF全文
Eight pigeons were trained on a delayed presence-versus-absence discrimination paradigm in which a sample stimulus was presented on some trials but not on others. If a sample was presented, then a response to one choice key produced food. If no sample was presented, a response to the other choice key produced food. The basic finding was that performance remained constant and well above 50% correct on no-sample trials as the retention interval increased, whereas performance dropped precipitously (to below 50% correct) on sample trials. In the second phase of the experiment, all of the trials were no-sample trials, and reinforcers were delivered probabilistically for one group of pigeons and according to time-based schedules for the other group. The exact reinforcement probabilities used in Phase 2 were those calculated to be in effect on no-sample trials in Phase 1 (according to a discrete-state model of performance). Subjects did not show exclusive preference for the richer alternative on no-sample trials in the first phase, but those in the probabilistic group developed near-exclusive preference for the richer alternative during the second phase. These data are inconsistent with the predictions of the discrete-state model, but are easily accommodated by an account based on signal detection theory, which also can be applied effectively to discrimination of event duration and the “subjective shortening” effect. 相似文献
17.
Marjolijn M. Vermande John H. van den Bercken Eric E. De Bruyn 《Journal of psychopathology and behavioral assessment》1996,18(1):49-70
In this study it was determined whether (a) classification as opposed to absence of classification has an effect on the quality of clinical hypotheses (b) the DSM-III-R and the CBCL have a different effect on the quality of clinical hypotheses, and (c) the potential difference between the DSM-III-R and the CBCL is moderated by the different number of syndromes identified by these systems. To investigate these questions, an experiment was conducted in which 86 clinicians generated hypotheses for six cases. The clinicians were divided into a DSM-III-R, a CBCL, and a control group. Of the six cases, two were classified by both classification systems as one syndrome, two were classified as one syndrome by the DSM-III-R but as two syndromes by the CBCL, and two were classified as two syndromes by the DSM-III-R but as one syndrome by the CBCL. The quality of the hypotheses was determined by means of four dependent variables selected from an overview of qualitative criteria: explanatory value, redundancy, possibility of operationalization, and specificity. No differences between the CBCL and the control groups were found. The DSM group performed better than the control group regarding explanatory value and redundancy. The DSM-III-R group also scored better than the CBCL group regarding explanatory value, particularly when the number of identified syndromes was two for the CBCL and one for the DSM-III-R. 相似文献
18.
Steiner D 《Science and engineering ethics》1996,2(4):457-468
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
19.
Patients with chronic stress and ambiguous symptoms are likely to be more frequent in primary care. Somatizers represent 75.8% of the patients in this study and executives 56% of the sample. Job stressors were present in 78.3% of executive men. This scenario suggests that the primary care physician has to be academically better prepared to fully understand and deal with stress problems in daily clinical practice. The physician must have skills to deal with stress at a curative and preventive level, extending those skills to the workplace. 相似文献
20.
The performance of pigeons trained to detect differences in the duration of stimuli was analysed using a matching model of signal detection. Two white stimuli, S1 and S2, differing in duration, were arranged with equal probability on the center key of a three-key chamber. S1 was systematically varied from 5 seconds to 25 seconds while S2 remained constant at 30 seconds. On completion of the center-key stimulus, a peck on the center key turned on the two red side keys. A left-key response was "correct" when S1 had been in effect on the center key and a right-key response was "correct" on S2 trials. A correct response produced a 3-second magazine light accompanied intermittently by food. Incorrect responses produced 3-second blackouts. Detection performance was measured under two procedures. In the first, the obtained reinforcement ratio was uncontrolled by allowing the number of food reinforcements obtained for correct left- and right-key responses to vary as the stimuli were changed. In the second procedure, the presentation of food reinforcement was controlled by holding the obtained reinforcement ratio constant. Discriminability changed as a function of stimulus differences under both procedures. No such trend was found in response bias. 相似文献