全文获取类型
收费全文 | 11936篇 |
免费 | 208篇 |
国内免费 | 205篇 |
专业分类
12349篇 |
出版年
2015年 | 38篇 |
2013年 | 38篇 |
2012年 | 1082篇 |
2011年 | 1232篇 |
2010年 | 276篇 |
2009年 | 149篇 |
2008年 | 958篇 |
2007年 | 904篇 |
2006年 | 843篇 |
2005年 | 718篇 |
2004年 | 643篇 |
2003年 | 556篇 |
2002年 | 541篇 |
2001年 | 340篇 |
2000年 | 399篇 |
1999年 | 194篇 |
1998年 | 78篇 |
1997年 | 65篇 |
1996年 | 274篇 |
1995年 | 34篇 |
1994年 | 97篇 |
1993年 | 91篇 |
1992年 | 96篇 |
1991年 | 110篇 |
1990年 | 102篇 |
1989年 | 101篇 |
1988年 | 118篇 |
1987年 | 127篇 |
1986年 | 98篇 |
1985年 | 121篇 |
1984年 | 109篇 |
1983年 | 135篇 |
1982年 | 91篇 |
1981年 | 91篇 |
1980年 | 79篇 |
1979年 | 84篇 |
1978年 | 74篇 |
1966年 | 48篇 |
1965年 | 132篇 |
1964年 | 104篇 |
1963年 | 126篇 |
1962年 | 55篇 |
1958年 | 114篇 |
1957年 | 97篇 |
1956年 | 87篇 |
1955年 | 49篇 |
1954年 | 38篇 |
1953年 | 33篇 |
1951年 | 35篇 |
1949年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Wolraich ML Lambert EW Baumgaertel A Garcia-Tornel S Feurer ID Bickman L Doffing MA 《Journal of abnormal child psychology》2003,31(4):445-455
This study evaluates a measurement model for Attention Deficit/Hyperactivity Disorder (ADHD). The DSM-IV divides 18 symptoms into two groups, inattentive and hyperactive/impulsive. Elementary school teachers rated 21,161 children in 4 locations: Spain, Germany, urban US, and suburban US. Confirmatory factor analysis suggested that the 2-factor model (inattention, hyperactivity/impulsivity) shows the best fit. A third factor, impulsivity, was too slight to stand-alone. Children with academic performance problems were distinguished by inattention, but children with behavior problems typically had elevations in inattention, hyperactivity, and impulsivity. Between-site differences were statistically significant, but so small that we conclude that same measurement model fits all 4 samples in 2 continents. 相似文献
992.
Cohen-Kettenis PT Owen A Kaijser VG Bradley SJ Zucker KJ 《Journal of abnormal child psychology》2003,31(1):41-53
This study examined demographic characteristics, social competence, and behavior problems in clinic-referred children with gender identity problems in Toronto, Canada (N = 358), and Utrecht, The Netherlands (N = 130). The Toronto sample was, on average, about a year younger than the Utrecht sample at referral, had a higher percentage of boys, had a higher mean IQ, and was less likely to be living with both parents. On the Child Behavior Checklist (CBCL), both groups showed, on average, clinical range scores in both social competence and behavior problems. A CBCL-derived measure of poor peer relations showed that boys in both clinics had worse ratings than did the girls. A multiple regression analysis showed that poor peer relations were the strongest predictor of behavior problems in both samples. This study—the first cross-national, cross-clinic comparative analysis of children with gender identity disorder—found far more similarities than differences in both social competence and behavior problems. The most salient demographic difference was age at referral. Cross-national differences in factors that might influence referral patterns are discussed. 相似文献
993.
This work employs Evoked Potential techniques as 19 participants are confronted with sentences that have the potential to produce scalar implicatures, like in Some elephants have trunks. Such an Underinformative utterance is of interest to pragmatists because it can be considered to have two different truth values. It can be considered true when taken at face value but false if one were to treat Some with the implicature Not All. Two accounts of implicature production are compared. The neo-Gricean approach (e.g., Levinson, 2000) assumes that implicatures intrude automatically on the semantics of a term like Some. Relevance Theory (Sperber & Wilson, 1985/1996) assumes that implicatures are effortful and not automatic. In this experiment, the participants are presented with 25 Underinformative sentences along with 25 sentences that are Patently True (e.g. Some houses have bricks) and 25 that are Patently False (e.g. Some crows have radios). As reported in an earlier study (Noveck, 2001), Underinformative sentences prompt strong individual differences. Seven participants here responded true to all (or nearly all) of the Underinformative sentences and the remaining 12 responded false to all (or nearly all) of them. The present study showed that those who responded false to the Underinformative sentences took significantly longer to do so that those who responded true. The ERP data indicate that: (a) the Patently True and Patently False sentences prompt steeper N400's--indicating greater semantic integration--than the Underinformative sentences and that (b) regardless of one's ultimate response to the Underinformative sentences, the N400's were remarkably flat, indicating no particular reaction to these sentences. Collectively, the data are taken to show that implicatures are part of a late-arriving, effort-demanding decision process. 相似文献
994.
Seventy-six participants performed a visual half-field lexical decision task at two different stimulus onset asynchronies (50 or 750 ms). Word targets were primed either by a highly associated word (e.g., CLEAN-DIRTY), a weakly associated word (e.g., CLEAN-TIDY), or an unrelated word (e.g., CLEAN-FAMILY) projected to either the same or opposite visual field (VF) as the target. In the short SOA, RVF-left hemisphere primes resulted in high associate priming regardless of target location (ipsilateral or contralateral to the prime) whereas LVF-right hemisphere primes produced both high and low associate priming across both target location conditions. In the long SOA condition, contralateral priming patterns converged, demonstrating only high associate priming in both VF locations. The results of this study demonstrate the critical role of interhemispheric transfer in semantic processing and indicate a need to elaborate current models of semantic processing. 相似文献
995.
Income is only weakly associated with both subjective well-being (SWB) and job satisfaction in the United States, a surprising finding in light of the importance placed on financial status in capitalistic societies. To explore this further, the authors examined intrinsic and extrinsic work orientations as potential moderators of the effects of financial compensation on SWB and job satisfaction. Master's of business administration students (N = 124) completed measures of work orientation and, 4 to 9 years later, reported their current salary, SWB, and job satisfaction. As predicted, individuals high in extrinsic orientation experienced higher SWB and job satisfaction to the degree that they earned more money, whereas those high in intrinsic orientation were lower on SWB at higher income levels. These findings are discussed in terms of the Values as Moderators Perspective of SWB and Cognitive Evaluation Theory. 相似文献
996.
In two studies, the authors investigated guilt as a response to group-based advantage. Consistent with its conceptualization as a self-focused emotion, White guilt was based in self-focused beliefs in racial inequality. Thus, guilt was associated with belief in White privilege (Study 1) and resulted from seeing European Americans as perpetrators of racial discrimination (Study 2). Just as personal guilt is associated with efforts at restitution, White guilt was predictive of support for affirmative action programs aimed at compensating African Americans. White guilt was not, however, predictive of support for noncompensatory efforts at promoting equality, such as affirmative action programs that increase opportunities (Study 2). In contrast, the other-focused emotion of group-based sympathy was a more general predictor of support for different affirmative action policies. Our findings demonstrate the benefits and limits of group-based guilt as a basis of support for social equality and highlight the value of understanding the specific emotions elicited in intergroup contexts. 相似文献
997.
Three studies address unresolved issues in value-behavior relations. Does the full range of different values relate to common, recurrent behaviors? Which values relate more strongly to behavior than others? Do relations among different values and behaviors exhibit a meaningful overall structure? If so, how to explain this? We find that stimulation and tradition values relate strongly to the behaviors that express them; hedonism, power, universalism, and self-direction values relate moderately; and security, conformity, achievement, and benevolence values relate only marginally. Additional findings suggest that these differences in value-behavior relations may stem from normative pressures to perform certain behaviors. Such findings imply that values motivate behavior, but the relation between values and behaviors is partly obscured by norms. Relations among behaviors, among values, and jointly among values and behavior exhibit a similar structure. The motivational conflicts and congruities postulated by the theory of values can account for this shared structure. 相似文献
998.
People experience a regulatory fit when they employ means of goal pursuit that fit their regulatory orientation, and this fit increases motivation that can enhance performance. The present studies extend previous research on regulatory fit to the classic motivational variables of fun and importance. They also examine for the first time the effect on performance of the fit between individuals' implicit theories about a task's fun or importance and their strategic engagement of the task as fun or important as induced by task instructions. In all three studies, task performance was better when the external task instructions "fit" rather than did not fit participants' implicit theory for the task. The implications of these findings for understanding the motivational effects of fun and importance are discussed. 相似文献
999.
Twelve patients with Alzheimer's disease (AD) and 15 healthy elderly control subjects were shown sets of luminance-defined letters, texture-defined letters, luminance-defined squares, and texture-defined squares. They were asked to name the letters or point to the target square on each page. The stimuli were graded into four levels of difficulty based on the amount of contrast between the figure and the background. Performance was measured in terms of the maximum level of difficulty at which the participant correctly identified or located the three figures. Contrary to expectations, no significant difference was found between the performance of AD patients and control subjects on texture discrimination tasks vs. luminance discrimination tasks. However, results indicate that AD patients are impaired in performing a task requiring them to locate a texture-defined target of known shape in a noisy background field. By contrast, AD patients show no significant deficit in a task requiring them to locate a texture-defined shape in a known location. This argues that the observed deficit in the location task is not due to a failure in the system that discriminates target texture from background texture (since both location and identification tasks require the same textural discriminations), but rather to an impairment of the system responsible for "finding things" (i.e., locating known targets at unknown locations). This observation suggests that AD patients may suffer selective damage to the dorsal "Where" pathway, which is responsible for localizing objects in space. 相似文献
1000.
This study tested the effects of different hypertension models on active avoidance learning in rats. Three-month-old male Wistar rats were divided randomly into six groups as follows: control (C), sham operated (sham), two kidney-one clip (2K-1C), one kidney-one clip (1K-1C), deoxycorticosterone-salt (DOCA), and N-omega-nitro-L-arginine-methyl ester (L-NAME) groups. Mean arterial blood pressures were significantly higher in four hypertensive groups compared with control and sham groups. The active avoidance training results indicated that hypertension state is associated with learning impairment. Thiobarbituric acid-reactive substances (TBARS) were determined as an indicator of lipid peroxidation in brain and hippocampus. Additionally, brain and hippocampus nitrite levels were studied. 相似文献