全文获取类型
收费全文 | 21741篇 |
免费 | 784篇 |
国内免费 | 7篇 |
出版年
2019年 | 267篇 |
2018年 | 358篇 |
2017年 | 304篇 |
2016年 | 336篇 |
2015年 | 231篇 |
2014年 | 332篇 |
2013年 | 1704篇 |
2012年 | 597篇 |
2011年 | 640篇 |
2010年 | 368篇 |
2009年 | 403篇 |
2008年 | 540篇 |
2007年 | 573篇 |
2006年 | 542篇 |
2005年 | 463篇 |
2004年 | 494篇 |
2003年 | 429篇 |
2002年 | 438篇 |
2001年 | 653篇 |
2000年 | 700篇 |
1999年 | 473篇 |
1998年 | 258篇 |
1997年 | 206篇 |
1996年 | 225篇 |
1995年 | 206篇 |
1992年 | 390篇 |
1991年 | 398篇 |
1990年 | 411篇 |
1989年 | 371篇 |
1988年 | 352篇 |
1987年 | 326篇 |
1986年 | 351篇 |
1985年 | 360篇 |
1984年 | 281篇 |
1983年 | 285篇 |
1980年 | 204篇 |
1979年 | 339篇 |
1978年 | 284篇 |
1977年 | 209篇 |
1976年 | 203篇 |
1975年 | 279篇 |
1974年 | 329篇 |
1973年 | 366篇 |
1972年 | 293篇 |
1971年 | 275篇 |
1970年 | 241篇 |
1969年 | 267篇 |
1968年 | 352篇 |
1967年 | 315篇 |
1966年 | 295篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
181.
ACTH 4-9 analog can retard spatial alternation learning in brain damaged and normal rats 总被引:1,自引:0,他引:1
Thirty adult male hooded rats (Long-Evans strain) were assigned randomly to one of three lesion groups (n = 10) and prepared with medial frontal, posterior parietal, or sham neocortical injuries. Following a recovery interval of 10-12 days, access to water was limited to 30 min per day and the rats were shaped to traverse a T-maze for a reward of sweetened water. After a pretraining criterion was attained, osmotic minipumps (Alzet 2002) were installed subcutaneously. The minipumps delivered chronically for the next 14 to 15 days either 0 or 1.2 micrograms of ACTH 4-9 dissolved in bacteriostatic saline per day while the rats were trained on a reinforced spatial alternation task. Analysis of the number of errors made to a criterion of at least 80% correct alternations in two consecutive training sessions, or a ceiling of 62 errors (attained by two rats with parietal lesions), revealed that learning was impaired in the rats with parietal injuries. Contrary to our hypothesis, animals receiving ACTH 4-9 committed more errors than their counterparts receiving only saline. 相似文献
182.
THE RELATIONSHIP BETWEEN RECRUITING SOURCE, APPLICANT QUALITY, AND HIRE PERFORMANCE: AN ANALYSIS BY SEX, ETHNICITY, AND AGE 总被引:2,自引:0,他引:2
This study investigated both an applicant pool and its resulting class of new hires in an attempt to clarify a number of empirical questions concerning recruiting source effectiveness. A pre-established database of applicants and hires for the job of life insurance agent in a large insurance company was analyzed for recruiting activity. Differences in applicant quality and new hire survival were found in favor of the informal recruiting sources. A second measure of hire success, new business commission credits, failed to show differences across recruiting sources. The informal recruiting sources yielded significantly higher selection ratios than did formal sources for all groups. Examination of recruiting source use showed significant group differences, with females and blacks using the formal recruiting sources more frequently than males, non-minorities, and Hispanics. While the informal recruiting sources yielded higher quality applicants and more successful hires for all groups, this research cautions that the implementation of revised recruiting policies must be carefully monitored for adverse effects on protected groups. 相似文献
183.
This study investigated the relationship between speech perception and speech production. An experimental technique called motor-motor adaptation was devised. Subjects produced a speech token repeatedly (20 to 40 repetitions), then produced a second token one time. These tokens all contained stop consonants and were subsequently analyzed for voice onset time. The results paralleled previous findings using the experimental procedure, perceptuomotor adaptation. The present study supports the notion of a perception-production link. 相似文献
184.
185.
Trace mineral analysis of human hair was utilized to determine whether violent and nonviolent criminals could be differentiated on the basis of concentrations of levels of major and trace minerals. 40 violent and 40 nonviolent inmates from a prison population were selected for study. 27 mineral levels were analyzed and a discriminant function analysis correctly classified 86% of the violent and 78% of the nonviolent inmates. The results lent support to the hypothesis that significantly different levels of trace minerals could be found between the two groups. 相似文献
186.
A I Murphy P M Lehrer R Karlin L Swartzman S Hochron B McCann 《Psychological reports》1989,65(2):691-698
12 subjects from an experiment on relaxation therapy for asthma were given the Harvard Group Scale of Hypnotic Susceptibility, Form A. Full scale hypnotic susceptibility scores were positively correlated, at a borderline significance, with improvement in the methacholine challenge test, a measure of asthma severity. Performance on the amnesia item of the Harvard Group Scale was correlated with improvement in self-reported symptoms of asthma. 相似文献
187.
F Postrach 《Psychiatrie, Neurologie, und medizinische Psychologie》1989,41(9):539-544
A case of episodic manifestation of semiparalysis agitans is described, accompanied by severe demential personality change and precursory hallucinatory symptoms, which is made the basis for the discussion of aspects of mental disorders, notably dementia and symptoms resembling schizophrenia, in Parkinsonian patients. By way of allusion to Glass, a diagnosis including a very extensive, complex, symptomatology is made of a Parkinsonian syndrome. 相似文献
188.
The Psychological Record - The present experiments investigated blocking effects in rhesus monkeys (Macaca mulatta) in a discrimination learning paradigm using a single stimulus modality. Two... 相似文献
189.
Despite importance for theories of perception, controversy exists as to whether information is available to the perceptual system about involuntary as well as voluntary eye movements. We measured the perceived direction of targets flashed briefly in an otherwise dark field during the primary phase of optokinetic afternystagmus (OKAN), an involuntary eye movement that persists in darkness following optokinetic stimulation. Perceived direction was measured by unseen pointing in one experiment and by pointing made under visual control in a second experiment. Pointing was essentially veridical in both experiments, indicating that accurate extra-retinal information about eye position (presumably, as efference copy) exists for OKAN. Illusory motion of visual targets, which can occur during involuntary oculomotor responses, therefore cannot be attributed to a lack of efference-copy signals for such eye movements. 相似文献
190.
We reported earlier that occlusion of the central retina and stationary edges have highly interactive effects on the gain of optokinetic nystagmus (OKN; Murasugi, Howard, & Ohmi, 1986). In this study, we explored this effect in more detail. A central occluding band of variable height, flanked by vertical bars, was superimposed onto an array of dots moving at 30 degrees per second. The height of the occluding band required to abolish OKN increased with the separation of the vertical bars. For bars 3.5 degrees apart, OKN was abolished in most subjects when a band only 6' high ran between them. For bars 75 degrees apart, a band at least 20 degrees in height was required to abolish the response. The effects of the stationary figure depended to some extent on the subject's attention, but only at intermediate values of bar separation. Both low- and high-level mechanisms are proposed to account for the results. 相似文献