全文获取类型
收费全文 | 24770篇 |
免费 | 590篇 |
国内免费 | 6篇 |
专业分类
25366篇 |
出版年
2016年 | 184篇 |
2015年 | 288篇 |
2014年 | 341篇 |
2013年 | 1547篇 |
2012年 | 576篇 |
2011年 | 666篇 |
2010年 | 460篇 |
2009年 | 599篇 |
2008年 | 680篇 |
2007年 | 693篇 |
2006年 | 659篇 |
2005年 | 675篇 |
2004年 | 598篇 |
2003年 | 563篇 |
2002年 | 649篇 |
2001年 | 222篇 |
2000年 | 209篇 |
1999年 | 225篇 |
1998年 | 237篇 |
1997年 | 196篇 |
1996年 | 249篇 |
1995年 | 244篇 |
1994年 | 200篇 |
1993年 | 359篇 |
1992年 | 321篇 |
1991年 | 288篇 |
1990年 | 288篇 |
1989年 | 472篇 |
1988年 | 412篇 |
1987年 | 518篇 |
1986年 | 440篇 |
1985年 | 448篇 |
1984年 | 392篇 |
1983年 | 299篇 |
1982年 | 386篇 |
1981年 | 390篇 |
1980年 | 374篇 |
1979年 | 345篇 |
1978年 | 410篇 |
1977年 | 447篇 |
1976年 | 463篇 |
1975年 | 470篇 |
1974年 | 335篇 |
1973年 | 202篇 |
1972年 | 199篇 |
1971年 | 178篇 |
1970年 | 173篇 |
1969年 | 151篇 |
1964年 | 165篇 |
1957年 | 163篇 |
排序方式: 共有10000条查询结果,搜索用时 6 毫秒
21.
22.
23.
24.
Three experiments were performed to study the influence of challenging incentives on feedback-assisted heart rate reduction for coronary-prone (Type A) and non-coronary-prone (Type B) males. In the first experiment, when subjects were given a competitive instructional set, Type As were significantly more successful relative to Type Bs in reducing their heart rate; with a noncompetitive set, Type Bs were significantly more successful than were Type As. In the second experiment, when told that heart rate reduction was a scarce ability, Type As reduced heart rate significantly better than did Type Bs; when told that heart rate reduction was a common ability, Type Bs achieved significantly greater heart rate reduction than did Type As. In the third experiment, when heart rate reduction was described as being instrumental to time-urgency (i.e., getting more done in less time), Type As reduced heart rate significantly bettern than did Type Bs; when heart rate reduction was described as being instrumental to relaxation, Type Bs were significantly better able to reduce heart rate. In all three studies, the incentives had no effect on heart rate when feedback was not provided. The results are discussed as support for the notion that Type A behavioral pattern characteristics can be exploited to reduce Type A symptoms. Implications for how coronary-prone individuals may be challenged to modify symptoms within the clinical setting are discussed. 相似文献
25.
Dr. H. Eidmann 《Zoomorphology》1924,2(3-4):567-610
26.
27.
28.
29.
30.
Akira Shimizu 《Journal of Ethology》1992,10(2):85-102
Anoplius eous Yasumatsu (Hymenoptera, Pompilidae) exhibits some outstanding nesting behavior. Females excavate a unicellular or multicellular
nest in wet ground, or dig a single-celled nest in rotten wood, or build clustered mud cells in narrow spaces between walls
of such substances as wood or vinyl sheets. The latter nest-type has been unknown within the subfamily Pompilinae. Females
prepare a nest-cell before hunting, and construct it further after hunting, leaving the prey near the nest (behavior-formula:
IVPTIOC). They transport their prey backward on the ground, grasping it in their mandibles by any part of the legs, and forward
on the surface film of water or on the ground, grasping it by the middle part of the 1st or 2nd legs. Their only prey is the
adult female semi-aquatic spider,Pardosa pseudoannulata (Lycosidae). These nesting and provisioning behavior patterns are compared with those of other pompilids. The position of
the present species in the behavioral evolution of the Pompilidae is suggested. 相似文献