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991.
Male and female Long-Evans rats were given open-field tests at 30 and/or 120 days of age. At 30 days of age, males and females did not differ in their open-field behavior. At 120 days of age, however, females locomoted more, reared more, and showed less wall-hugging than males, regardless of whether or not the animals had received tests in the open field at 30 days of age. The appearance of sex differences was due to an increase in the scores of the females between 30 and 120 days of age. 相似文献
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993.
Learning & Behavior - Fish were allowed to choose, in a T-maze, between various combinations of goalboxes containing either food or a mirror, or nothing. Only food and a mirror maintained... 相似文献
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997.
Morphine, which is obtained from poppies, has pharmacological properties which make it both a powerful pain-relieving drug and a narcotic feared for the dependency which it induces in those who use it. Study of the mode of action of morphine has revealed related endogenous substances in the brain. These brain opiates have remarkable properties, which researchers are just beginning to discover. 相似文献
998.
Jean J Fried 《Endeavour》1985,9(3):112-116
Because it is generally freely and plentifully available in temperate regions the importance of water tends to be under-rated. In reality, it is fundamental to the economic strength of all countries and ensuring adequate supplies in face of growing needs is of paramount importance. A comprehensive review of the water resources of the European Community reveals that while there are many regional differences — especially in the degree of dependence on ground, as opposed to surface, water — overall supplies are adequate, but only if very carefully managed. 相似文献
999.
Testosterone during Pregnancy and Gender Role Behavior of Preschool Children: A Longitudinal, Population Study 总被引:2,自引:1,他引:2
Melissa Hines Susan Golombok John Rust Katie J. Johnston Jean Golding & Avon Longitudinal Study of Parents Children Study Team 《Child development》2002,73(5):1678-1687
Levels of testosterone (T) and sex hormone–binding globulin (SHBG) were measured in blood samples from pregnant women and related to gender role behavior in 342 male and 337 female offspring at the age of 3.5 years. Gender role behavior was assessed using the Pre–School Activities Inventory, a standardized measure on which a parent indicates the child's involvement with sex–typical toys, games, and activities. Levels of T, but not SHBG, related linearly to gender role behavior in preschool girls. Neither hormone related to gender role behavior in boys. Other factors, including the presence of older brothers or sisters in the home, parental adherence to traditional sex roles, the presence of a male partner in the home, and maternal education, did not relate to gender role behavior in this sample and did not account for the relation observed between T and behavior. Although other, unmeasured factors may explain the relation, the results suggest that normal variability in T levels prenatally may contribute to the development of individual differences in the gender role behavior of preschool girls. 相似文献
1000.
Mother-Child Relationships as Sources of Support or Stress: A Comparison of Competent, Average, Aggressive, and Anxious Dyads 总被引:1,自引:0,他引:1
We tested the proposition that mother-child relationships can be sources of support or stress, by comparing patterns of mother-child interactions in a problem-solving task that children completed with their own and with an unfamiliar mother. 4 groups of preschoolers (n = 30 in each group)—identified on the basis of teacher ratings as socially competent, average, aggressive, or anxious—participated. Mothers of competent and average children were highly positive and reciprocal toward their own and unfamiliar children. Mothers of aggressive and anxious children were only positive and reciprocal toward unfamiliar children but generally indiscriminate (aggressive group) or aversive and negatively reciprocal (anxious group) toward their own. Children in all 4 groups tended to be reciprocal toward their own mothers, but only competent and average children were reciprocal toward unfamiliar mothers also. Aggressive and anxious children generally responded to unfamiliar mothers by ignoring or actively rejecting their overtures. Results (1) indicate that the relationship with the primary caregiver may serve as a major source of support or stress in the preschool years; (2) focus attention on the dynamic organization of interactions rather than on the presence or frequency of particular behaviors, indicating that a dynamic of reciprocity enables children and mothers to adapt positively to the ever changing demands of new social situations; (3) point to the need to develop new means of assessing relationships to better understand how they influence development; and (4) highlight the importance of incorporating transactional models in the diagnosis and treatment of childhood dysfunctions rather than accounting for them solely in terms of limited skills in parents or children. 相似文献