全文获取类型
收费全文 | 12686篇 |
免费 | 528篇 |
国内免费 | 2篇 |
专业分类
13216篇 |
出版年
2021年 | 73篇 |
2020年 | 135篇 |
2019年 | 167篇 |
2018年 | 236篇 |
2017年 | 260篇 |
2016年 | 261篇 |
2015年 | 200篇 |
2014年 | 262篇 |
2013年 | 1433篇 |
2012年 | 453篇 |
2011年 | 493篇 |
2010年 | 306篇 |
2009年 | 320篇 |
2008年 | 484篇 |
2007年 | 440篇 |
2006年 | 430篇 |
2005年 | 433篇 |
2004年 | 436篇 |
2003年 | 419篇 |
2002年 | 448篇 |
2001年 | 221篇 |
2000年 | 183篇 |
1999年 | 198篇 |
1998年 | 212篇 |
1997年 | 204篇 |
1996年 | 163篇 |
1995年 | 173篇 |
1994年 | 159篇 |
1993年 | 179篇 |
1992年 | 167篇 |
1991年 | 140篇 |
1990年 | 144篇 |
1989年 | 126篇 |
1988年 | 120篇 |
1987年 | 131篇 |
1986年 | 117篇 |
1985年 | 147篇 |
1984年 | 188篇 |
1983年 | 190篇 |
1982年 | 192篇 |
1981年 | 173篇 |
1980年 | 141篇 |
1979年 | 132篇 |
1978年 | 177篇 |
1977年 | 156篇 |
1976年 | 160篇 |
1975年 | 141篇 |
1974年 | 156篇 |
1973年 | 105篇 |
1972年 | 76篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
921.
Forge J 《Science and engineering ethics》2004,10(3):531-542
I ask whether weapons research is ever justified. Weapons research is identified as the business of the engineer. It is argued
that the engineer has responsibility for the uses to which the tools that he designs can be put, and that responsibility extends
to the use of weapons. It is maintained that there are no inherently defensive weapons, and hence there is no such thing as
‘defensive’ weapons research. The issue then is what responsibilities as a professional the engineer has in regard to such
research. An account is given to ground the injunction not to provide the means to harm as a duty for the engineers. This
account is not, however, absolutist, and as such it allows justifiable exceptions. The answer to my question is thus not that
weapons research is never justified but there must be a strong assurance that the results will only be used as a just means
in a just cause. 相似文献
922.
Hale LR Goldstein DS Abramowitz CS Calamari JE Kosson DS 《Behaviour research and therapy》2004,42(6):697-710
Although the hypothesis that psychopathic individuals are characterized by a reduced capacity for experiencing anxiety is central to many theories of psychopathy, most prior studies have examined anxiety and fear measures generally considered outdated in the literature. Moreover, prior findings are mixed, with several studies reporting no relationships between psychopathy and anxiety, and others suggesting negative relationships for the affective, interpersonal aspects of the disorder and positive relationships for the antisocial behavior dimension. To examine whether psychopathy dimensions are associated with contemporary measures of anxiety, the Anxiety Sensitivity Index and State Trait Anxiety Inventory-Trait scale were administered to 157 male inmates. Participants also completed the MMPI-derived Welsh Anxiety Scale (WAS), commonly used in psychopathy studies. Analyses provide no evidence for a negative relationship between psychopathy's affective, interpersonal factor and anxiety sensitivity after controlling for trait anxiety. Trait anxiety and WAS scores were positively associated with the antisocial behavior dimension of psychopathy. Findings do replicate prior relationships between the WAS and psychopathy, suggesting the WAS may measure aspects of negative affectivity that differ from anxiety. 相似文献
923.
Plucker JA Robinson NM Greenspon TS Feldhusen JF McCoach DB Subotnik RF 《The American psychologist》2004,59(4):268-9; author reply 269-71
924.
The authors investigate a previously overlooked yet important objective for employee job search--seeking leverage against the current employer. They explore the outcomes and correlates of leverage-seeking search and how it may differ from the more traditional objective for engaging in job search--to change jobs. Results show that leverage-seeking and separation-seeking search objectives associate with different outcomes. The authors also find that characteristics of the work situation and individual differences associate with leverage-seeking search and relate differently with the 2 job search objectives. Implications for practice and the advancement of job search research are discussed. 相似文献
925.
Effects of anorectic drugs on food intake under progressive-ratio and free-access conditions in rats 下载免费PDF全文
The effects of two anorectic drugs, dexfenfluramine and phentermine, on food intake under different food-access conditions were examined. Experiment 1 compared the effects of these drugs on food intake under a progressive-ratio (PR) schedule and free-access conditions. Dexfenfluramine decreased food intake under both conditions, but the doses required to decrease intake under free-access conditions were higher than those required to reduce intake under the PR condition. Intermediate doses of phentermine sometimes increased breaking points, and higher doses decreased them. Phentermine decreased food intake at the same doses under both access conditions. Thus the potency of dexfenfluramine, but not phentermine, to decrease food-maintained behavior depended upon the food-access condition. Experiment 2 used a novel mixed progressive-ratio schedule of food delivery to study the duration of drug effects. Sessions consisted of five components separated by 3-hr timeouts. The ratio requirement reset at the beginning of each component and a new breaking point was obtained. Both dexfenfluramine and phentermine dose-dependently decreased breaking points early in the session. In some rats, compensatory increases in breaking point were observed. That is, breaking points later in the session increased over control levels, resulting in no change in the total number of food pellets earned for the session compared to control. The present findings suggest that the effects of some anorectic drugs depend upon the access conditions for food; increasing the effort to obtain food may enhance their ability to decrease food-maintained behavior. 相似文献
926.
In a change detection paradigm, the global orientation of a natural scene was incrementally changed in 1 degree intervals. In Experiments 1 and 2, participants demonstrated sustained change blindness to incremental rotation, often coming to consider a significantly different scene viewpoint as an unchanged continuation of the original view. Experiment 3 showed that participants who failed to detect the incremental rotation nevertheless reliably detected a single-step rotation back to the initial view. Together, these results demonstrate an important dissociation between explicit change detection and visual memory. Following a change, visual memory is updated to reflect the changed state of the environment, even if the change was not detected. 相似文献
927.
928.
929.
Pierce JD Cohen AB Ulrich PM 《Journal of comparative psychology (Washington, D.C. : 1983)》2004,118(1):14-19
Substantial variation exists in the importance of olfaction in influencing individuals' preferences, yet the sources of this variation remain elusive. The authors explored responsivity to 2 odorants as 1 potential source. Participants (N = 258) completed the Affective Impact of Odor Scale and were assessed for responsivity to the putative human pheromone androstenone and amyl acetate. Results showed a significant relationship between odorant responsivity and self-reports of the influence of odors. People able to smell androstenone more commonly reported odors as having a negative effect on interpersonal relationships than did people anosmic to androstenone, whereas responsivity to amyl acetate was associated with positive effects of odors on relationships. Responsivity to certain odorants may be an important factor affecting human social interactions. 相似文献
930.
A meta-analytic review of prospective memory and aging 总被引:16,自引:0,他引:16
A meta-analysis of prospective memory (PM) studies revealed that in laboratory settings younger participants outperform older participants on tests of both time- and event-based PM (rs=-.39 and -.34, respectively). Event-based PM tasks that impose higher levels of controlled strategic demand are associated with significantly larger age effects than event-based PM tasks that are supported by relatively more automatic processes (rs=-.40 vs. -.14, respectively). However, contrary to the prevailing view in the literature, retrospective memory as measured by free recall is associated with significantly greater age-related decline (r=-.52) than PM, and older participants perform substantially better than their younger counterparts in naturalistic PM studies (rs=.35 and.52 for event- and time-based PM, respectively). 相似文献