全文获取类型
收费全文 | 34420篇 |
免费 | 1457篇 |
国内免费 | 28篇 |
出版年
2020年 | 382篇 |
2019年 | 485篇 |
2018年 | 692篇 |
2017年 | 654篇 |
2016年 | 769篇 |
2015年 | 498篇 |
2014年 | 640篇 |
2013年 | 2807篇 |
2012年 | 1163篇 |
2011年 | 1173篇 |
2010年 | 677篇 |
2009年 | 738篇 |
2008年 | 970篇 |
2007年 | 1007篇 |
2006年 | 894篇 |
2005年 | 799篇 |
2004年 | 760篇 |
2003年 | 707篇 |
2002年 | 713篇 |
2001年 | 1102篇 |
2000年 | 1106篇 |
1999年 | 816篇 |
1998年 | 381篇 |
1997年 | 354篇 |
1996年 | 327篇 |
1995年 | 337篇 |
1993年 | 325篇 |
1992年 | 662篇 |
1991年 | 617篇 |
1990年 | 589篇 |
1989年 | 573篇 |
1988年 | 568篇 |
1987年 | 506篇 |
1986年 | 507篇 |
1985年 | 558篇 |
1984年 | 473篇 |
1983年 | 442篇 |
1982年 | 347篇 |
1979年 | 495篇 |
1978年 | 361篇 |
1976年 | 346篇 |
1975年 | 383篇 |
1974年 | 457篇 |
1973年 | 484篇 |
1972年 | 408篇 |
1971年 | 348篇 |
1969年 | 337篇 |
1968年 | 419篇 |
1967年 | 379篇 |
1966年 | 364篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
Personnel Reaction Blank (PRB) scores and biographical data were obtained from two groups of registered nurses; a deviant group, represented by those who had official actions taken against their nursing license by the Minnesota Board of Nursing (n=53) and a non-deviant group of nurses (n=79) randomly selected from a broader population. The hypothesis that the deviant group of nurses would exhibit lower PRB scores, on average, compared to the non-deviant group was confirmed. The mean PRB scores for the deviant nurses (m=32.43) were significantly lower (p.01) than for the randomly selected non-deviant nurses (m=35.06). A multiple regression logit analysis showed that in addition to PRB scores, college degree, sex, and household income variables were also significantly related (p.001) to deviant and non-deviant group assignment; nonetheless, PRB significantly differentiated these groups after holding these variables constant.This study is based on the Masters thesis research of the first author. We acknowledge the help of the study subjects who contributed their time and effort. 相似文献
963.
People become subject to political and social violence when governments fail to give priority to basic health care or education. Attempts to meet foreign obligations also produce severe economic recessions which further impede efforts to improve the general quality of life of disadvantaged populations. Since multiple factors contribute to violence, a multidisciplinary approach is best suited to address the problem. For example, poverty and its associated risks are linked to violence, but living in poverty does not necessarily engender violence. Living in poverty may, however, fuel high rates of child mortality, illiteracy, malnutrition, excessive population growth, street children, and familial disintegration. An integrated action program was developed in Brazil for at-risk individuals and their families based upon the idea of building and reinforcing family ties and intergenerational togetherness. Undernourished infants, street children, the handicapped, women subjected to violence, and neglected senior citizens received special interventions in the program described in the text. 相似文献
964.
965.
Ronald C. Martella Ph.D. Ian J. Leonard B.S. Nancy E. Marchand-Martella Ph.D. Martin Agran Ph.D. 《Journal of Behavioral Education》1993,3(1):77-86
We examined the effects of a self-monitoring program on reducing the frequency of negative statements of a student with mild mental retardation who was enrolled in a self-contained classroom at a middle school. A changing criterion design was used within a multiple baseline design across two classroom periods. Additionally, the frequency of positive statements was reported. The results showed a decrease in the number of negative statements, and an increase in the number of positive statements. Maintenance data collected up to 8 weeks after the program ended indicated that the student continued to emit positive rather than negative statements. The use of this procedure to decelerate undesirable behavior is discussed. 相似文献
966.
Carol Z. Garrison Ph.D. Cheryl L. Addy Ph.D. Robert E. McKeown Ph.D. Steven P. Cuffe M.D. Kirby L. Jackson A.B. Jennifer L. Waller Ph.D. 《Journal of child and family studies》1993,2(4):339-352
To determine the frequency and correlates of nonsuicidal physically self-damaging acts in 12–14 year olds, a two stage epidemiologic survey with a self-administered questionnaire (N=3283) followed by a psychiatric interview of a subsample of the adolescents and their parents (N=444) was used. Prevalence estimates of interview validated nonsuicidal physically self-damaging acts were 2.46% in males and 2.79% in females. Significant relationships were found between nonsuicidal physically self-damaging acts and suicidal ideation, major depression and undesirable life events. Data suggest that physically self-damaging acts occur at substantial rates during early adolescence. The strong correlation between nonsuicidal self-destructive acts and both suicidal ideation and major depression clarifies prior conflicting reports in the literature and suggests that a history of self-damaging acts should be taken into consideration when evaluating for possible depression and suicide risk. 相似文献
967.
968.
Tolbutamide has previously been shown to amplify the pressor effects of “exogenous” catecholamines in conscious dogs, possibly due to sensitization of the α1-adrenoreceptor-mediated vasoconstriction. The objective of this study was to examine if tolbutamide also amplifies the pressor effects of “endogenous” catecholamines released during psychological stress (classical Pavlovian aversive conditioning). Experiments were conducted in β-adrenoreceptor-blocked (propranolol, 1 mg/kg, i.v.) conscious dogs (n=4) trained in classical aversive conditioning. Conditioning was accomplished by following a tone (CS+) with a 1/2 second shock; another tone (CS-) was not followed by any shock and served as control. With saline pretreatment, aversive conditioning (i.e., CS+) increased mean arterial pressure (MAP) only by approximately 4.7% when compared to CS-, whereas with tolbutamide (45 mg/kg, i.v.) pretreatment, the increase in MAP induced by CS+ beyond what was induced by the CS- (approximately 6.2%) was significantly (p<0.05) larger than that with saline pretreatment. In isolated canine femoral arterial segments (n=4), the vasoconstrictor effect of phenylephrine (an α1-agonist) at 5×10?6M (which was the EC50 value) was amplified by 2×10?2M of tolbutamide from 54.0±2.0% to 66.9±2.1%. In conclusion, tolbutamide amplifies the pressor effects of “endogenous” catecholamines in conscious dogs, possibly by sensitization of the α1-adrenoreceptor-mediated vasoconstriction. This mechanism of action is novel and has not been reported with other agents. 相似文献
969.
Sjoerd C. de Vries Astrid M. L. Kappers Jan J. Koenderink 《Attention, perception & psychophysics》1993,53(1):71-80
We used quadratic shapes in several psychophysical shape-from-stereo tasks. The shapes were elegantly represented in a 2-D parameter space by the scale-independentshape index and the scale-dependentcurvedness. Using random-dot stereograms to depict the surfaces, we found that the shape of hyperbolic surfaces is slightly more difficult to recognize than the shape of elliptic surfaces. We found that curvedness (and indirectly, scale) has little or no influence on shape recognition. 相似文献
970.
Christopher C. Pagano Paula Fitzpatrick M. T. Turvey 《Attention, perception & psychophysics》1993,54(1):43-54
Subjects wielded occluded rods, with or without attached masses, and reported the distances reachable with their distal tips. Experiments 1–3 compared wielding about the wrist, the elbow, and the shoulder. Experiments 4 and 5 compared free wielding, using the whole arm, with wielding only about the wrist. The two comparisons, respectively, were of spatial and temporal variations in the rod’s rotational inertia. Perceived extent was found to be constant in both comparisons. This constancy was tied to the inertia tensorI ij defined about a point that remains a fixed distance from the object during wielding—an invariant of the spatially and temporally dependent patterning of mechanical energy impressed upon the tissues of the body. Discussion focused on the reciprocal action and perception capabilities of multisegmented limbs, the tensorial relations in the neurobiology of dynamic touch, and the strategy of understanding perceptual constancy through invariants. 相似文献