全文获取类型
收费全文 | 40695篇 |
免费 | 1600篇 |
国内免费 | 27篇 |
专业分类
42322篇 |
出版年
2020年 | 423篇 |
2019年 | 542篇 |
2018年 | 734篇 |
2017年 | 721篇 |
2016年 | 839篇 |
2015年 | 572篇 |
2014年 | 697篇 |
2013年 | 3424篇 |
2012年 | 1301篇 |
2011年 | 1321篇 |
2010年 | 831篇 |
2009年 | 886篇 |
2008年 | 1160篇 |
2007年 | 1204篇 |
2006年 | 1102篇 |
2005年 | 969篇 |
2004年 | 929篇 |
2003年 | 897篇 |
2002年 | 925篇 |
2001年 | 1190篇 |
2000年 | 1206篇 |
1999年 | 916篇 |
1998年 | 479篇 |
1997年 | 442篇 |
1996年 | 433篇 |
1995年 | 445篇 |
1994年 | 414篇 |
1992年 | 760篇 |
1991年 | 705篇 |
1990年 | 661篇 |
1989年 | 648篇 |
1988年 | 639篇 |
1987年 | 592篇 |
1986年 | 597篇 |
1985年 | 653篇 |
1984年 | 567篇 |
1983年 | 535篇 |
1982年 | 460篇 |
1979年 | 586篇 |
1978年 | 478篇 |
1977年 | 437篇 |
1976年 | 452篇 |
1975年 | 492篇 |
1974年 | 568篇 |
1973年 | 587篇 |
1972年 | 495篇 |
1971年 | 405篇 |
1968年 | 478篇 |
1967年 | 412篇 |
1966年 | 405篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
983.
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
984.
985.
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
986.
987.
988.
The crane's foot: The rise of the pedigree in human genetics 总被引:1,自引:1,他引:0
Robert G. Resta 《Journal of genetic counseling》1993,2(4):235-260
The standard pedigree used by geneticists is intimately connected to the history of genetics. Pedigrees drawn today are based on standards established in the early decades of the twentieth century. Those standards were established by geneticists who pursued an active interest in eugenics. The slightly different standards followed in America vs. England to some extent followed the stronger support of Mendelism by the Americans, as well as the individual preferences of the leading human geneticists in those countries. 相似文献
989.
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
990.
Robert Rosen 《Theoretical medicine and bioethics》1993,14(2):89-100
Physics says that it cannot deal with the mind-brain problem, because it does not deal in subjectivities, and mind is subjective. However, biologists (among others) still claim to seek a material basis for subjective mental processes, which would thereby render them objective. Something is clearly wrong here. I claim that what is wrong is the adoption of too narrow a view of what constitutes ‘objectivity’, especially in identifying it with what a ‘machine’ can do. I approach the problem in the light of two cognate circumstances: (a) the ‘measurement problem’ in quantum physics, and (b) the objectivity of standard mathematics, even though most of it is beyond the reach of ‘machines’. I argue that the only resolution to such problems is in the recognition that closed loops of causation are ‘objective’; i.e. legitimate objects of scientific scrutiny. These are explicitly forbidden in any machine or mechanism. A material system which contains such loops is called ‘complex’. Such complex systems thus must possess nonsimulable models; i.e. models which contain impredicativities or ‘self-references’ which cannot be removed, or faithfully mapped into a single coherent syntactic time-frame. I consider a few of the consequences of the above, in the context of thus redrawing the boundary between subject and object. 相似文献