全文获取类型
收费全文 | 1411篇 |
免费 | 54篇 |
专业分类
1465篇 |
出版年
2023年 | 9篇 |
2022年 | 14篇 |
2021年 | 14篇 |
2020年 | 19篇 |
2019年 | 31篇 |
2018年 | 41篇 |
2017年 | 38篇 |
2016年 | 51篇 |
2015年 | 35篇 |
2014年 | 32篇 |
2013年 | 193篇 |
2012年 | 62篇 |
2011年 | 54篇 |
2010年 | 39篇 |
2009年 | 29篇 |
2008年 | 34篇 |
2007年 | 53篇 |
2006年 | 49篇 |
2005年 | 39篇 |
2004年 | 38篇 |
2003年 | 40篇 |
2002年 | 47篇 |
2001年 | 20篇 |
2000年 | 28篇 |
1999年 | 20篇 |
1998年 | 16篇 |
1997年 | 23篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 20篇 |
1993年 | 21篇 |
1992年 | 12篇 |
1990年 | 12篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 21篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 15篇 |
1981年 | 14篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 14篇 |
1977年 | 9篇 |
1973年 | 9篇 |
1971年 | 11篇 |
1968年 | 12篇 |
1950年 | 8篇 |
排序方式: 共有1465条查询结果,搜索用时 0 毫秒
91.
92.
It was hypothesized that male day care teachers who had adopted the feminine role of caregiver would score feminine in their personality traits and would reinforce children for feminine behaviors and punish them for masculine behaviors. A random sample of 20 male caregivers was contrasted to 20 male engineers on personality traits as assessed by The Adjective Checklist (ACL). Twenty female caregivers were also contrasted to the personality traits and the sex-typed contingency behaviors of the male caregivers. Feminine traits were defined by raw scores on the Abasement, Nurturance, Affiliation, Succorance, and Deference scales of the ACL. Masculine traits were represented by raw scores on the Achievement, Dominance, Endurance, and Autonomy scales. The Fagot-Patterson Checklist was employed to determine sex-typed contingency behaviors. Both male and female caregivers reinforced children significantly more for feminine behaviors than masculine behaviors (as defined by The Fagot-Patterson Checklist) and punished masculine behaviors more than feminine behaviors. The personalities of the male caregivers corresponded to the feminine direction of their female counterparts, but they were not significantly more feminine than the male engineers. The female caregivers, however, scored significantly more feminine in personality than the male engineers.This study is based on a dissertation submitted by Bryan E. Robinson to the Department of Child Development — Family Relations, University of North Carolina at Greensboro, in partial fulfillment of the requirements for the Ph.D. 相似文献
93.
Three experiments showed that constraints imposed early in learning have different effects on variability when they are in effect and after they are removed. Task constraints, which determine how something can be done, limited the number of possible responses in a computer game. Variability constraints, which specify how differently something must be done, required that each response differ from some number of prior responses. Less restrictive constraints (Experiments 1 and 2) produced higher variability during the constraints. More restrictive constraints (Experiments 2 and 3) led to higher variability after the constraints were relaxed. The authors discuss how these differences reflect strategies acquired during the constraints (default rules) and modified in closely related ways (exception rules) afterward. 相似文献
94.
The effects of varying interaural time delay (ITD) and interaural intensity difference (IID) were measured in normal-hearing sighted and congenitally blind subjects as a function of eleven frequencies and at sound pressure levels of 70 and 90 dB, and at a sensation level of 25 dB (sensation level refers to the pressure level of the sound above its threshold for the individual subject). Using an 'acoustic' pointing paradigm, the subject varied the IID of a 500 Hz narrow-band (100 Hz) noise (the 'pointer') to coincide with the apparent lateral position of a 'target' ITD stimulus. ITDs of 0, +/-200, and +/-400 micros were obtained through total waveform delays of narrow-band noise, including envelope and fine structure. For both groups, the results of this experiment confirm the traditional view of binaural hearing for like stimuli: non-zero ITDs produce little perceived lateral displacement away from 0 IID at frequencies above 1250 Hz. To the extent that greater magnitude of lateralization for a given ITD, presentation level, and center frequency can be equated with superior localization abilities, blind listeners appear at least comparable and even somewhat better than sighted subjects, especially when attending to signals in the periphery. The present findings suggest that blind listeners are fully able to utilize the cues for spatial hearing, and that vision is not a mandatory prerequisite for the calibration of human spatial hearing. 相似文献
95.
Hofer SM Christensen H Mackinnon AJ Korten AE Jorm AF Henderson AS Easteal S 《Psychology and aging》2002,17(2):194-208
The influence of a genetic risk factor, apolipoprotein E (apoE) epsilon4 variant, was assessed in older adults aged 70 to 94 on 3 occasions over 7 years. The results of latent growth curve analyses are reported for individuals genotyped for apoE at the 2nd measurement occasion (n = 601) and for a subsample of individuals without probable or definite dementia during the 1st or 2nd occasion (n = 434). ApoE-epsilon4 status was a significant predictor of level and change in memory performance and change in speed performance in the full sample, and of initial level and change in memory performance in the nondemented subsample. These results support previous findings that apoE-epsilon4 is associated with accelerated memory deterioration in individuals without clinical dementia. 相似文献
96.
97.
This article reviews relevant literature as to the labor pool of qualified individuals with disabilities and employment in information technology (IT) sector jobs. First, the article reviews the empirical literature on barriers to employment in IT for persons with disabilities. The examination then is extended to studies of barriers to employment for individuals with disabilities in other employment sectors. Findings illustrate the limited experiences that IT and non-IT companies have in employing and accommodating employees with disabilities. Implications are discussed for enhancing the employment of qualified workers with disabilities in IT through research, education, training, and mentoring programs. 相似文献
98.
99.
100.
Scientific misconduct includes the fabrication, falsification, and plagiarism (FFP) of concepts, data or ideas; some institutions
in the United States have expanded this concept to include “other serious deviations (OSD) from accepted research practice.”
It is the absence of this OSD clause that distinguishes scientific misconduct policies of the past from the “research misconduct”
policies that should be the basis of future federal policy in this area. This paper introduces a standard for judging whether
an action should be considered research misconduct as distinguished from scientific misconduct: by this standard, research
misconduct must involve activities unique to the practice of science and must have the potential to negatively affect the
scientific record. Although the number of cases of scientific misconduct is uncertain (only the NIH and the NSF keep formal
records), the costs are high in terms of the integrity of the scientific record, diversions from research to investigate allegations,
ruined careers of those eventually exonerated, and erosion of public confidence in science. Existing scientific misconduct
policies vary from institution to institution and from government agency to government agency; some have highly developed
guidelines that include OSD, others have no guidelines at all. One result has been that the federal False Claims Act has been
used to pursue allegations of scientific misconduct. As a consequence, such allegations have been adjudicated in federal courts,
rather than judged by scientific peers. The federal government is now establishing a first-ever research misconduct policy
that would apply to all research funded by the federal government regardless of which agency funded the research or whether
the research was carried out in a government, industrial or university laboratory. Physical scientists, who up to now have
only infrequently been the subject of scientific misconduct allegations, must nonetheless become active in the debate over
research misconduct policies and how they are implemented since they will now be explicitly covered by this new federal wide
policy.
Disclaimer: The authors are grateful for the support for conduct of this research provided by the United States Department of Energy
(DOE). The views expressed in this paper are solely those of the authors and were formed and expressed without reference to
positions taken by DOE or the Pacific Northwest National Laboratory (PNNL). The views of the authors are not intended either
to reflect or imply positions of DOE or PNNL. 相似文献