全文获取类型
收费全文 | 21395篇 |
免费 | 858篇 |
国内免费 | 4篇 |
专业分类
22257篇 |
出版年
2020年 | 227篇 |
2019年 | 322篇 |
2018年 | 402篇 |
2017年 | 360篇 |
2016年 | 448篇 |
2015年 | 304篇 |
2014年 | 379篇 |
2013年 | 1855篇 |
2012年 | 678篇 |
2011年 | 789篇 |
2010年 | 466篇 |
2009年 | 522篇 |
2008年 | 637篇 |
2007年 | 707篇 |
2006年 | 625篇 |
2005年 | 551篇 |
2004年 | 589篇 |
2003年 | 546篇 |
2002年 | 516篇 |
2001年 | 554篇 |
2000年 | 595篇 |
1999年 | 440篇 |
1998年 | 306篇 |
1997年 | 229篇 |
1996年 | 238篇 |
1995年 | 234篇 |
1994年 | 231篇 |
1993年 | 196篇 |
1992年 | 343篇 |
1991年 | 326篇 |
1990年 | 342篇 |
1989年 | 304篇 |
1988年 | 289篇 |
1987年 | 270篇 |
1986年 | 279篇 |
1985年 | 296篇 |
1984年 | 223篇 |
1983年 | 255篇 |
1982年 | 197篇 |
1979年 | 284篇 |
1978年 | 259篇 |
1975年 | 225篇 |
1974年 | 253篇 |
1973年 | 280篇 |
1972年 | 237篇 |
1971年 | 217篇 |
1969年 | 197篇 |
1968年 | 255篇 |
1967年 | 240篇 |
1966年 | 211篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
232.
Strengthening local alcohol programs so as to emphasize primary prevention is an active concern among mental health professionals; yet interventions intended to achieve this aim have produced only modest shifts in program orientation in most communities. An analysis of data obtained from those active in local affairs in a small community, using Q-sort techniques, suggested that contrasting perspectives toward alcohol abuse as a social problem may stand as an unseen barrier to relevant change. 相似文献
233.
234.
Mark Tausig 《American journal of community psychology》1987,15(3):337-351
This paper argued that problems of coordination and integration of community mental health systems are best approached from a network perspective in which all linkages between agencies are considered simultaneously. Structural coordination and integration can be assessed through the analysis of these linkages. The utility of this approach was demonstrated by deriving a typology of system "cracks" from network analytic constructs. A network analysis of a community mental health service network was then generated to illustrate how these cracks can be empirically identified. It is suggested that mental health planners will find both the network analytic approach and the typology of cracks useful for addressing problems of coordination and integration. 相似文献
235.
236.
The functional development of cardiac and adrenal medullary responses to reflex activation of the sympathetic nervous system was studied in preweanling spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) normotensive rats. Pups of the two strains received injections of insulin or saline at 2, 4, 8, 12, or 16 days of age and were sacrificed 3 h later. Insulin administration produces a significant decrease in circulating levels of glucose which in turn results in a centrally mediated increase in sympathetic outflow. The induction of ornithine decarboxylase (ODC) in heart and the depletion of epinephrine from the adrenal medulla served as tissue markers of functional sympathetic neurotransmission. WKY and SHR pups had comparable levels of ODC activity in heart under basal conditions. In contrast, levels of catecholamines in the adrenals were greater in SHR pups at 2 and 4 days of age. Following insulin administration, SHR pups exhibited a greater induction of cardiac ODC activity at 2, 4, and 8 days of age compared to age-matched WKY controls. However, there were no differences between SHR and WKY pups in the magnitude of the adrenal medullary response to insulin-induced hypoglycemia. These alterations in sympathetic-target tissue development during the first postnatal week of life may contribute in part to the higher arterial pressures maintained by SHRs throughout the lifespan. 相似文献
237.
F H de Jonge J Burger F van Haaren H Overdijk N E van de Poll 《Behavioral and neural biology》1987,47(3):369-383
The influence of sexual experience on preference behavior was investigated in adult female rats. In the first experiment, preference behavior for sexually active males versus estrous females was investigated in female rats who were experienced with mounting behavior. Preference of these mount experienced females was compared to preference of females who were naive in this respect. Mount experience with estrous females induced a female-directed preference in ovariectomized female rats, irrespective of whether the females were treated with OIL or with testosterone-propionate (500 micrograms TP, injected once 48 h prior to testing). Sexually naive, OIL-treated females did not show a preference for males or females, but TP induced a preference for a male. Individual differences in mount frequency were not correlated with preference behavior. In the second experiment, the influence of experience with feminine sexual responses on preference behavior was investigated. OIL-treated and TP-treated females oriented equally toward males and females when they had been given the opportunity to copulate with males prior to the preference tests. The results strongly suggest that prior sexual experience is an important determinant of preference behavior. The female's behavior during sexual interactions was, however, not predictive of later preference. 相似文献
238.
Individual differences in cognitive arithmetic 总被引:2,自引:0,他引:2
Unities in the processes involved in solving arithmetic problems of varying operations have been suggested by studies that have used both factor-analytic and information-processing methods. We designed the present study to investigate the convergence of mental processes assessed by paper-and-pencil measures defining the Numerical Facility factor and component processes for cognitive arithmetic identified by using chronometric techniques. A sample of 100 undergraduate students responded to 320 arithmetic problems in a true-false reaction-time (RT) verification paradigm and were administered a battery of ability measures spanning Numerical Facility, Perceptual Speed, and Spatial Relations factors. The 320 cognitive arithmetic problems comprised 80 problems of each of four types: simple addition, complex addition, simple multiplication, and complex multiplication. The information-processing results indicated that regression models that included a structural variable consistent with memory network retrieval of arithmetic facts were the best predictors of RT to each of the four types of arithmetic problems. The results also verified the effects of other elementary processes that are involved in the mental solving of arithmetic problems, including encoding of single digits and carrying to the next column for complex problems. The relation between process components and ability measures was examined by means of structural equation modeling. The final structural model revealed a strong direct relation between a factor subsuming efficiency of retrieval of arithmetic facts and of executing the carry operation and the traditional Numerical Facility factor. Furthermore, a moderate direct relation between a factor subsuming speed of encoding digits and decision and response times and the traditional Perceptual Speed factor was also found. No relation between structural variables representing cognitive arithmetic component processes and ability measures spanning the Spatial Relations factor was found. Results of the structural modeling support the conclusion that information retrieval from a network of arithmetic facts and execution of the carry operation are elementary component processes involved uniquely in the mental solving of arithmetic problems. Furthermore, individual differences in the speed of executing these two elementary component processes appear to underlie individual differences on ability measures that traditionally span the Numerical Facility factor.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
239.
Eyeheight-scaled information about affordances: a study of sitting and stair climbing 总被引:6,自引:0,他引:6
Previous work has shown that both the perceived and actual critical (maximum) heights of surfaces that afford "sitting on " and "climbing on" can be expressed as constant proportions of each actor's leg length. The current study provides evidence that these judgments of critical action boundaries are based on an existing source of size and distance information that is already scaled with reference to the actor's eyeheight. In Experiment 1 changes in judgments of "perceived eyeheight" (an index of the intrinsic scalar) as a function of viewing distance were shown to be highly correlated with changes in the maximum height that was perceived to afford sitting on or climbing on. In Experiments 2 and 3 observers wore 10-cm blocks and made judgments about whether the heights of various surfaces afforded sitting or climbing. The use of eyeheight-scaled information as the basis for their estimates predicted the obtained pattern of errors in these judgments. With a modicum of experience wearing the blocks, however, observers were able to retune accurately their critical action boundary to a degree that would not have been predicted from their consistent overestimation of the height of the block on which they were standing. These results have implications for understanding how observers obtain information about their specific action boundary. 相似文献
240.
I Rock F Halper J DiVita D Wheeler 《Journal of experimental psychology. Human perception and performance》1987,13(3):344-352
When a figure moves behind a narrow aperture in an opaque surface, if it is perceived as a figure, its shape will often appear distorted. Under such anorthoscopic conditions, the speed or direction of the object's motion is ambiguous. However, when the observer simultaneously tracks a moving target, a figure is always perceived, and its precise shape is a function of the speed or direction of tracking. The figure is seen as moving with the speed or in the direction of the target. Thus, it is argued that eye movement serves as a cue to the figure's motion, which, in turn, determines its perceived length or orientation. 相似文献