全文获取类型
收费全文 | 754篇 |
免费 | 34篇 |
出版年
2023年 | 6篇 |
2021年 | 5篇 |
2020年 | 11篇 |
2019年 | 20篇 |
2018年 | 32篇 |
2017年 | 22篇 |
2016年 | 34篇 |
2015年 | 26篇 |
2014年 | 25篇 |
2013年 | 68篇 |
2012年 | 31篇 |
2011年 | 24篇 |
2010年 | 25篇 |
2009年 | 23篇 |
2008年 | 21篇 |
2007年 | 21篇 |
2006年 | 31篇 |
2005年 | 25篇 |
2004年 | 23篇 |
2003年 | 19篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 16篇 |
1998年 | 13篇 |
1997年 | 19篇 |
1996年 | 7篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1975年 | 5篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1970年 | 7篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有788条查询结果,搜索用时 15 毫秒
41.
The neural changes that limit the sensitive period for avian song development are unknown, but neurons in a forebrain region critical for song learning, the lMAN, exhibit experience-driven changes in NMDAR subunit expression that could regulate sensitive period closure. Specifically, NR2B levels in lMAN decrease during song acquisition, potentially reducing synaptic plasticity by decreasing NMDAR EPSC duration and/or affecting NMDAR-coupled intracellular cascades. While rearing birds in isolation extends the sensitive period and also delays the developmental changes in NR2B expression and NMDAR physiology, recent work indicates that a transition to faster NMDAR currents does not preclude further song learning. However, NR2B mRNA expression in isolates remains elevated beyond the age at which NMDAR currents shorten, leaving open the possibility that NR2B levels regulate closure of the sensitive period through effects other than those mediated by NMDAR current duration. To determine whether the experience-driven decrease in NR2B expression in lMAN closes the sensitive period, we promoted this change in gene expression either by treating isolation-reared zebra finches briefly with testosterone (T-isolates) or by allowing males limited access to conspecific song (pre-exposed isolates). We then assessed if these birds could acquire song from tutors after the normal close of the sensitive period. Despite a normal decline in NR2B expression, T-isolate and pre-exposed isolate birds learned tutor songs heard from d65-90, while normally reared birds did not. These findings suggest that the normal decline in NR2B expression with lMAN is not sufficient for sensitive period closure. 相似文献
42.
Therapy of bipolar disorders is a rapidly evolving field. Lithium has efficacy in classic bipolar disorders whereas divalproex sodium and carbamazepine may have broader spectrum efficacy that includes non-classic bipolar disorder. In the last 10 years, a series of anticonvulsants have been approved for marketing in the United States. Gabapentin has indirect g-aminobuytric acid-ergic actions, is generally well tolerated, and appears to have anxiolytic, analgesic, and hypnotic effects. Lamotrigine has antiglutamatergic actions and is generally well tolerated (aside from rash in 1 in 10, and serious rash in 1 in 1,000 patients). Lamotrigine is indicated for maintenance treatment in bipolar disorder. Emerging evidence suggests lamotrigine may have utility in bipolar disorder patients with depression and treatment-refractory rapid cycling, as well as analgesic effects. Topiramate and zonisamide may allow both weight loss, while topiramate may have specific efficacy in bulimia, binge eating disorder, and alcohol dependence. Two small studies found oxcarbazepine had similar efficacy to lithium and haloperidol in acute mania. Phenytoin, an older anticonvulsant, may have adjunctive acute mania efficacy. Levetiracetam, a newer anticonvulsant, may be worth exploring and has minimal drug-drug interactions. None of these newer agents has been shown effective in a large placebo controlled trial for acute mania. Although the clinical profiles of these newer anticonvulsants do not appear to overlap markedly with divalproex and carbamazepine (except perhaps for oxcarbazepine), these novel agents may still offer important new options in relieving a variety of specific target symptoms in patients with bipolar disorder. 相似文献
43.
Parsing silhouettes: the short-cut rule. 总被引:2,自引:0,他引:2
Many researchers have proposed that, for the purpose of recognition, human vision parses shapes into component parts. Precisely how is not yet known. The minima rule for silhouettes (Hoffman & Richards, 1984) defines boundary points at which to parse but does not tell how to use these points to cut silhouettes and, therefore, does not tell what the parts are. In this paper, we propose the short-cut rule, which states that, other things being equal, human vision prefers to use the shortest possible cuts to parse silhouettes. We motivate this rule, and the well-known Petter's rule for modal completion, by the principle of transversality. We present five psychophysical experiments that test the short-cut rule, show that it successfully predicts part cuts that connect boundary points given by the minima rule, and show that it can also create new boundary points. 相似文献
44.
45.
46.
Joel J. Silverman Nirbhay N. Singh Sharon J. Carmanico Kathy A. Lindstrom Al M. Best Sydney Clearfield 《Journal of child and family studies》1999,8(1):71-89
We investigated the psychological impact of an organized visit to Polish concentration camps on Jewish-American adolescents. Eighty-seven adolescents who participated in a B'nai B'rith memorial visit to concentration camps in Poland completed measures of general psychological adjustment and posttraumatic stress disorder (PTSD) at four time-points: pretest, posttest, 6-month follow-up and 12-month follow-up. Measures included the SCL-90-R, the Mississippi Scale for PTSD, and the Impact of Events Scale (IES) for PTSD. On the SCL-90-R, changes in somatization, interpersonal sensitivity, obsessive-compulsive tendencies, depression, anxiety, and phobic anxiety were observed over time, with peak symptom scores at posttest and 6-month follow-up. Scores on the Mississippi Scale for PTSD and the IES Intrusion subscale also increased at 6-months. Predictors of PTSD symptoms on the Mississippi Scale included previous psychiatric treatment and SCL-90-R symptoms of paranoia, depression, and psychosis. Elevated psychotic symptoms on the SCL-90-R predicted PTSD symptoms on the IES. Jewish adolescents with preexisting symptoms of generalized distress or psychoticism appeared at increased risk for PTSD symptoms following exposure to Holocaust stimuli. This study contributes a prospective, multi-measure assessment of trauma reactions in adolescents. 相似文献
47.
Manish Singh Gregory D. Seyranian Donald D. Hoffman 《Attention, perception & psychophysics》1999,61(4):636-660
Many researchers have proposed that, for the purpose of recognition, human vision parses shapes into component parts. Precisely how is not yet known. The minima rule for silhouettes (Hoffman & Richards, 1984) defines boundary points at which to parse but does not tell how to use these points to cut silhouettes and, therefore, does not tell what the parts are. In this paper, we propose the short-cut rule, which states that, other things being equal, human vision prefers to use the shortest possible cuts to parse silhouettes. We motivate this rule, and the well-known Petter’s rule for modal completion, by the principle of transversality. We present five psychophysical experiments that test the short-cut rule, show that it successfully predicts part cuts that connect boundary points given by the minima rule, and show that it can also create new boundary points. 相似文献
48.
This paper discusses the results of a systematic review of the Condom Social Marketing (CSM) program which was implemented in Fiji by a non-profit organization for a period of 5?years. The CSM program was introduced during a decade when Fiji was recording an escalating number of new Human Immunodeficiency Virus (HIV) infections. The aim of the program was to increase the awareness and utilization of safe sexual practices among the most vulnerable group??the youths??which had reported the highest incidences of sexually transmitted infections. Program assessment revealed that the CSM program had reportedly increased the acceptability, accessibility, and usage of their TRY TiME condoms in Fiji. We conducted a survey on a sample of sexually active people during January?CFebruary 2009 to examine their prevailing level of knowledge about HIV/AIDS, sexual behavior/practices, and risk perception. The results showed that, despite the high level of awareness about HIV/AIDS among survey participants, people did not consistently practice safe sexual behavior and commonly identified themselves as at low risk of acquiring HIV. This paper concludes that more extensive behavior change programs are needed in order to influence people to change their risky sexual practices and reassess their risk perceptions. 相似文献
49.
Infants begin to segment novel words from speech by 7.5 months, demonstrating an ability to track, encode and retrieve words in the context of larger units. Although it is presumed that word recognition at this stage is a prerequisite to constructing a vocabulary, the continuity between these stages of development has not yet been empirically demonstrated. The goal of the present study is to investigate whether infant word segmentation skills are indeed related to later lexical development. Two word segmentation tasks, varying in complexity, were administered in infancy and related to childhood outcome measures. Outcome measures consisted of age‐normed productive vocabulary percentiles and a measure of cognitive development. Results demonstrated a strong degree of association between infant word segmentation abilities at 7 months and productive vocabulary size at 24 months. In addition, outcome groups, as defined by median vocabulary size and growth trajectories at 24 months, showed distinct word segmentation abilities as infants. These findings provide the first prospective evidence supporting the predictive validity of infant word segmentation tasks and suggest that they are indeed associated with mature word knowledge. A video abstract of this article can be viewed at http://www.youtube.com/watch?v=jxzLi5oLZQ8 . 相似文献
50.
The relation between temperament and happiness was assessed in a sample of 441 children aged 7–14 years drawn from a population
in Northern India. Parents assessed their children’s happiness and rated their children’s temperament using the Emotionality,
Activity, and Sociability Temperament Survey (EAS). Children self-reported their own happiness using a single-item measure,
the Oxford Happiness Scale Short Form, and the Subjective Happiness Scale. Parents’ temperament ratings conformed to the four
factor structure proposed by Buss and Plomin (Temperament: early developing personality traits. Lawrence Erlbaum Associates,
Hillsdale, 1984): Emotionality, Activity, Sociability, and Shyness. Temperament accounted for between 4 and 11% of the variance in children’s
happiness depending on the measures. Children who were more social and active, and less shy, were happier. This result parallels
the well-established relation between happiness and personality in adults and is similar to recent research on happiness and
temperament in children; temperament traits akin to extraversion were positively associated with happiness. However, despite
that neuroticism and its temperament counterpart are strongly and consistently linked to happiness in adults, the relation
between happiness and the temperament trait associated with neuroticism (i.e., Emotionality) was weak. This suggests that
the relations between temperament and happiness in children may not completely generalize across cultures. 相似文献