全文获取类型
收费全文 | 25099篇 |
免费 | 915篇 |
国内免费 | 11篇 |
专业分类
26025篇 |
出版年
2020年 | 317篇 |
2019年 | 294篇 |
2018年 | 472篇 |
2017年 | 522篇 |
2016年 | 494篇 |
2015年 | 317篇 |
2014年 | 406篇 |
2013年 | 2012篇 |
2012年 | 812篇 |
2011年 | 867篇 |
2010年 | 529篇 |
2009年 | 454篇 |
2008年 | 732篇 |
2007年 | 680篇 |
2006年 | 614篇 |
2005年 | 515篇 |
2004年 | 493篇 |
2003年 | 463篇 |
2002年 | 493篇 |
2001年 | 749篇 |
2000年 | 772篇 |
1999年 | 570篇 |
1998年 | 273篇 |
1997年 | 225篇 |
1992年 | 454篇 |
1991年 | 422篇 |
1990年 | 449篇 |
1989年 | 421篇 |
1988年 | 405篇 |
1987年 | 406篇 |
1986年 | 410篇 |
1985年 | 431篇 |
1984年 | 336篇 |
1983年 | 303篇 |
1982年 | 241篇 |
1981年 | 218篇 |
1979年 | 392篇 |
1978年 | 280篇 |
1977年 | 252篇 |
1976年 | 222篇 |
1975年 | 342篇 |
1974年 | 374篇 |
1973年 | 353篇 |
1972年 | 332篇 |
1971年 | 293篇 |
1970年 | 262篇 |
1969年 | 324篇 |
1968年 | 364篇 |
1967年 | 325篇 |
1966年 | 332篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
The twisted helix: An essay on genetic counselors,eugenics, and social responsibility 总被引:2,自引:0,他引:2
Resta RG 《Journal of genetic counseling》1992,1(3):227-243
The American eugenics movement had a significant impact on American social history, and analysis of the movement illustrates the relationship among science, scientists, and society. The history of the American eugenics movement as well as more recent examples of eugenic thought and biological determinism are reviewed. The need for genetic counselors to confront eugenic issues in their own profession and in society is discussed. 相似文献
192.
Raymond G. Miltenberger Jan Larson Mark Doerner Laurie Orvedal 《Behavioral Interventions》1992,7(1):23-34
Direct care and supervisory staff in five residential training programs for persons with mental retardation in North Dakota rated the acceptability of six staff management procedures. Overall, staff rated “Instructions”, “Instructions and Modeling”, “Feedback and Praise”, and “Instructions, Feedback, and Praise”, as significantly more acceptable than “Self-Management” and “Self-Management, Feedback and Praise”. There was a significant group by treatment interaction in which supervisors and direct care staff had significantly different acceptability rating for four of the six procedures. The results were further analyzed by group and implications and future research are discuessed. 相似文献
193.
Clint Bowers Eduardo Salas Carolyn Prince Michael Brannick 《Behavior research methods》1992,24(4):503-506
Teams are playing an increasingly important role in the workplace. However, reviews of the team performance literature have suggested that there are serious deficiencies in our understanding of team processes and performance (e.g., Dyer, 1984). These difficulties may be attributable, in part, to the lack of laboratory methodologies to investigate team performance. This paper describes the use of low-fidelity simulations as a potentially useful paradigm for researching team coordination and performance. This paradigm is advantageous in that it offers relatively high levels of experimental control and task representation at a low cost. 相似文献
194.
Rick Gurnsey G. Keith Humphrey Paula Kapitan 《Attention, perception & psychophysics》1992,52(3):263-276
Recent physiological studies (von der Heydt & Peterhans, 1989) suggest that the orientation of subjective contours is encoded very early in the visual system (V2 in monkey). This result is seemingly at odds with existing psychophysical data which suggest that the detection of subjective contours involves selective attention. It is argued that certain subjective contours are registered in a reflexive (bottom-up) manner by the visual system but that selective attention may be needed to gain access to this representation. To assess this suggestion, a visual-search task was used in which subjects were to detect the presence of a horizontal (vertical) subjective contour (defined by offset gratings) in a variable number of vertical (horizontal) subjective contours (also defined by offset gratings). When there were no competing organizations within the display, detection was indeed independent of the number of nontarget distractors, that is, selective attention was unnecessary. In a second experiment, we found that a curved form (a crescent defined by subjective contours) was easier to detect in a background of vertical bars (also defined by subjective contours) than vice versa, namely, a search asymmetry paralleling those found by Treisman and Gormican (1988). A final experiment showed that when the horizontal and vertical bars of the first experiment formed textured regions, they could be discriminated at very brief display durations (30–120 msec), However, when the line terminations aligned along the subjective contour were tapered rather than abrupt, discrimination dropped off with the degree of tapering. The latter result is consistent with the assumption that the registration of subjective contours in V2 involves the integration of responses from aligned, end-stopped cells found in VI (von der Heydt & Peterhans, 1989). 相似文献
195.
This article presents a model of how attractiveness influences adjustment and reviews the relevant evidence. The model suggests that attractiveness influences adjustment through a three-stage process. Varying levels of physical attractiveness create differential responses in other people (Stage 1). These differential responses in others as a function of a person's appearance then result in differential treatment of the person (Stage 2), with such differential treatment eventually resulting in differential adjustment (Stage 3). These three stages are considered to occur in a reciprocal manner across the life span. Empirical support is found for each stage from early childhood to adulthood. Attractiveness accounts for 6% to 16% of the variance in measures of subjective adjustment as well as sociometric and behavioral measures of interpersonal adjustment. 相似文献
196.
We tested the validity of the egotism model of human helplessness. In contrast to the original theoretical approach of Seligman and his associates, which points to response-outcome noncontingency as the main source of helplessness, the egotism alternative proposes that repeated failure itself is the critical determinant of helplessness symptoms. Repeated failure threatens the self-esteem of the subject, who supposedly engages in a least-effort strategy during the test phase of a typical learned helplessness study, which results in performance impairment. To examine the egotism explanation, we gave subjects noncontingent-feedback training with or without repeated failure on five consecutive discrimination problems. In two experiments, noncontingent-feedback preexposure produced helplessness deficits in performance on avoidance learning, whereas repeated failure appeared irrelevant to helplessness. This and our other findings from research are inconsistent with the egotism explanation and support instead Seligman's original proposal, in which helplessness is attributed to prolonged experience with noncontingency. 相似文献
197.
The relationship between amphetamine-induced stereotyped behavior and a neuroendocrine index of arousal, plasma corticosterone (CCS), was investigated. 6-Hydroxydopamine lesions of the caudate-putamen, which produced dopamine depletions of 60%, blocked stereotypy and prolonged the elevation in corticosterone associated with d-amphetamine treatment (5 mg/kg). Similar dopamine depleting lesions of the nucleus accumbens, which attenuated the locomotor, but not the stereotypic, response to AMPH did not have this effect on CCS. This pattern of results supports the hypothesis that stereotypy has a coping function which may serve to alter arousal and further suggests important differences between the nigrostriatal and mesolimbic dopamine projections in modulating the responsiveness of the neuroendocrine system. These results have implications for understanding the function of behavioral stereotypies common to a number of psychopathological conditions, including schizophrenia and childhood autism. 相似文献
198.
Thirsty rats were used in order to determine whether a vinegar solution, which had been paired with an injection of lithium chloride, could block the formation of an association between a pentobarbital- and a lithium chloride-induced state. During phase 1 the rats in the blocking group had a 2.0% vinegar solution paired with an injection of 240 mg/kg of lithium chloride, during phase 2 these rats were reexposed to the vinegar prior to each injection of 20 mg/kg of pentobarbital and 240 mg/kg of lithium chloride, and during phase 3 these rats were given access to a novel 0.75% saccharin solution and were injected with pentobarbital after saccharin removal. Animals with this history did not form an association between the pentobarbital- and lithium chloride-induced states during phase 2 as evidenced by their refusal to consume the saccharin solution over repeated pairings of saccharin with pentobarbital during phase 3. Control groups that received forward pairings of pentobarbital and lithium chloride, in the absence of a previously conditioned vinegar solution during phase 2, formed an association between pentobarbital and lithium chloride. These findings indicate that drug states and flavors can interfere with each others' capacity to predict the occurrence of lithium chloride. 相似文献
199.
This study compared normal developing children, aged 34 to 51 mo., on comprehension and production of relative dimensional adjectives using object manipulations in a close elicitation procedure and on Piagetian operational tests of conservation of continuous quantity, length, reversibility and seriation. Analysis indicated a significant difference on the expressive language performance of the transitional and the concrete operational children over the preoperational children, but no significant differences occurred between the first two groups. Children who performed better on seriation were significantly better on expressive language performance. Children classified as operational for length performed better on all language measures than those classified as nonoperational. Reversibility and conservation of a continuous quantity did not differentiate children. 相似文献
200.