全文获取类型
收费全文 | 34479篇 |
免费 | 700篇 |
国内免费 | 5篇 |
专业分类
35184篇 |
出版年
2020年 | 383篇 |
2019年 | 402篇 |
2018年 | 626篇 |
2017年 | 600篇 |
2016年 | 646篇 |
2015年 | 446篇 |
2014年 | 607篇 |
2013年 | 2920篇 |
2012年 | 1034篇 |
2011年 | 1132篇 |
2010年 | 658篇 |
2009年 | 744篇 |
2008年 | 1039篇 |
2007年 | 993篇 |
2006年 | 945篇 |
2005年 | 881篇 |
2004年 | 864篇 |
2003年 | 842篇 |
2002年 | 832篇 |
2001年 | 1009篇 |
2000年 | 964篇 |
1999年 | 775篇 |
1998年 | 438篇 |
1997年 | 408篇 |
1996年 | 347篇 |
1995年 | 359篇 |
1993年 | 362篇 |
1992年 | 645篇 |
1991年 | 565篇 |
1990年 | 619篇 |
1989年 | 528篇 |
1988年 | 502篇 |
1987年 | 489篇 |
1986年 | 502篇 |
1985年 | 577篇 |
1984年 | 513篇 |
1983年 | 470篇 |
1982年 | 398篇 |
1981年 | 357篇 |
1980年 | 321篇 |
1979年 | 451篇 |
1978年 | 424篇 |
1977年 | 355篇 |
1976年 | 348篇 |
1975年 | 434篇 |
1974年 | 492篇 |
1973年 | 455篇 |
1972年 | 345篇 |
1968年 | 356篇 |
1966年 | 329篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
For 40 males who smoked 20 cigarettes a day titratable acidity of the urine was significantly correlated with nicotine/cotinine excretion at several sample intervals, as was urinary pH, but not urinary acidity and daily cigarette consumption or serum COHB. 相似文献
172.
173.
When people are exposed to misleading details after a witnessed event, they often claim that they saw the misleading details as part of the event. We refer to this as themisinformation effect. In four experiments, involving 570 subjects, we explored the role that discrepancy detection plays in the misinformation effect. Experiment 1 showed that subjects who naturally read a post-event narrative more slowly were more resistant to the effects of misleading information contained in the narrative. In Experiment 2, subjects who naturally read more slowly were more likely to detect a discrepancy between what they were reading and what was stored in their memory. In Experiment 3, subjects who were instructed to read slowly were more likely to detect a discrepancy than were those who were instructed to read quickly. In Experiment 4, subjects who were instructed to read slowly were more resistant to misleading postevent information. Taken together, these results suggest that longer reading times are associated with a greater scrutiny of postevent information. This leads to an increased likelihood that discrepancies will be detected and that the misinformation will be resisted. 相似文献
174.
John F. Halpin 《Synthese》1986,69(3):325-340
In his (1981) paper, Stalnaker has revised his old theory of conditionals and has given the revision an interesting defense. Indeed, Stalnaker shows that this new theory meets the standard objections put to the old. However, I argue that the revision runs into difficulties in the context of quantum mechanics: If Stalnaker's theory of the conditional is assumed, then from plausible assumptions certain Bell-like conflicts with experiment can be derived. This result, I go on to argue, is a good reason to reject Stalnaker's theory, at least for the quantum mechanical context.I wish to thank Arthur Fine, Paul Teller, Dorothy Grover, and Anil Gupta for their helpful comments and criticisms on earlier drafts of this paper. 相似文献
175.
Temporal integration and vibrotactile backward masking 总被引:1,自引:0,他引:1
P M Evans J C Craig 《Journal of experimental psychology. Human perception and performance》1986,12(2):160-168
Subjects were presented with vibrotactile target patterns to their left index fingertips. The target patterns varied in the number of line segments that they contained and were presented in the presence or absence of a backward-masking stimulus. The stimulus onset asynchrony (SOA) between the target and masker was varied. In an identification task, subjects' errors indicated that the effect of the masker at brief SOAs was to increase the perceived number of line segments in the target. This effect diminished with increasing SOA, and at the longest SOAs subjects confused targets with patterns containing the same number of line segments but varying in how the line segments were related. In an estimation task, the effect of the masker was to increase the number of line segments estimated to be contained in the target pattern. The effect of the masker at brief SOAs is discussed in terms of an integration theory of vibrotactile backward masking. At longer SOAs, the results suggest that the masker may interfere with the extraction of relational information in the target pattern. 相似文献
176.
A homogeneous sample of normal adults living in a religious order in a study of age effects on reference as a cohesive device in discourse production and comprehension. Narrative and procedural discourse were examined across various levels of complexity and stimulus/response requirements. Results indicate that significant ambiguity of reference emerges in the younger elderly group (age 64-76) in comparison to the middle-aged group (age 27 to 55), and increases markedly in the older elderly group (age 77-92). Related impairments of comprehension and cognition were also observed. These findings are interpreted to be general features of linguistic variation with advancing age. Communicative consequences of ambiguous reference are discussed. 相似文献
177.
Recent findings indicate that post-training glucose injections can modulate memory storage for inhibitory (passive) avoidance training. Experiment I extended these findings to determine whether glucose, like other memory modulating treatments, enhances memory storage when administered after training with low footshock and impairs memory storage after high footshock training. In Experiment I, male Sprague-Dawley rats were trained in a one-trial inhibitory avoidance task using either a brief footshock (0.5 mA, 0.7 s) or slightly more intense footshock kept on until escape (0.7 mA, mean escape latency = 3.4 s). Immediately after training, each rat received a subcutaneous injection of glucose (100 mg/kg). When tested for retention performance 24 h later, the glucose-injected animals exhibited enhanced retention performance for low footshock training and impaired retention for high footshock training. Experiment II determined whether pretreatment with adrenergic antagonists blocked the effects of glucose on memory. Pretreatment with the alpha- or beta-adrenergic receptor antagonists, phenoxybenzamine, or propranolol, respectively, had no effect on acquisition or retention in animals trained with the brief footshock and did not affect glucose facilitation of that memory. In animals trained to escape footshock, phenoxybenzamine did not attenuate the amnesia produced by glucose. Propranolol-pretreated animals had impaired retention whether or not they received post-training amnestic injections of glucose; glucose had no effect on retention in these amnestic animals. These findings add further support to the view that glucose release after training and treatment may represent a physiological response subsequent to epinephrine release in modulating memory storage processing. 相似文献
178.
Jane A. Goldman Robert H. Lerman John H. Contois John N. Udall Jr. 《Journal of abnormal child psychology》1986,14(4):565-577
Despite speculation that sucrose consumption affects behavior, little empirical information is available. Accordingly, this study investigated the effect of sucrose consumption on the behavior of eight preschool children. Children were tested individually using a double-blind, crossover design. On separate mornings each child received 6 ounces of juice, sweetened on one morning with sucrose and on the other with an artificial sweetener. Children were observed for 90 minutes following the drinks, alternating between 15-minute sessions of work on structured tasks and 15-minute sessions of free play. Following the sucrose drink the children showed a decrement in performance in the structured testing situation, and they demonstrated more inappropriate behavior during free play. These differences in behavior were most pronounced approximately 45 to 60 minutes after the drinks. Thus, the study provides objective evidence in young children of a rather subtle, yet significant, time-dependent behavior effect of sucrose ingestion.This research was funded in part by grants from the General Research Grants Committee, University Hospital, Boston University Medical Center, and from the University of Connecticut Research Foundation. The project was conducted at the Clinical Research Center, Massachusetts Institute of Technology (National Institute of Health/General Clinical Research Center Grant 5M01-RR00088-20). We would like to express our appreciation to the many staff members of the Clinical Research Center for their extensive cooperation in helping us to plan and carry out this study, and to the director and staff of Technology Children's Center for their assistance in helping us to reach interested families. We also would like to thank the parents and children who participated in the study. Portions of this paper were presented at the annual meeting of the American Psychological Association, Toronto, August 1984. 相似文献
179.
180.