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951.
Human activities affect both the amount and configuration of habitat. These changes have important ecological implications that can be measured as changes in landscape connectivity. I investigated how urbanization interacts with the initial amount and aggregation of habitat to change dispersal potential, restoration potential, and the risk of spatially extensive disturbances. I used a factorial set of simulated landscapes and subjected each landscape to habitat loss by overlaying 66 different US urban areas. I used a common connectivity metric, CONNECT, to assess the magnitude and direction of changes for a range of dispersal distances. My results show that the relationship between habitat loss and connectivity loss is non-linear and subject to interactions between the spatial patterns of habitat distribution, urban morphology, and dispersal capabilities. The implications of a given urban form vary widely as a function of habitat distribution and dispersal capabilities. This implies that impact assessments, restoration activities, and conservation planning should consider historical habitat distribution when evaluating observed changes in connectivity. While my results clearly show that more aggregated or continuous habitats are more vulnerable to connectivity loss, this approach can also be used to identify landscapes where restoring connectivity will be particularly effective, for example through placement of stepping stone habitats.  相似文献   
952.
Motherhood postponement and fertility decline have been observed in almost all developed countries. In this article, we aim to assess some of the potential determinants of first childbirth timing in Europe, in a comparative perspective, using data from the European Community Household Panel Survey (ECHP). We estimate, separately by country, hazard rates for the timing at first childbirth conditioning to education and work characteristics. Moreover, in order to explain differences between European countries, we decompose the differences between rates in the part due to the national population composition by specific characteristics and the part due to different propensities for women with given characteristics.  相似文献   
953.
Despite the diversity of the variables considered, explanatory models of migration do not fully incorporate the locality of origin as a scale of observation for migratory behaviour. Migration is often perceived to generate notions of territory; conversely, are local territories drivers of mobility? If so, in what forms, and by what means? This article analyses international migration from the city of Kaolack in Senegal, with particular focus on the role of the neighbourhood in migration dynamics. Here, the neighbourhood is seen as relatively homogeneous and singular historical and social entity. The ties that are established and maintained from one generation to the next take the form of shared lifestyles and modes of organization which may influence inhabitants’ propensity to emigrate.  相似文献   
954.
Using a unique sample on ageing first generation immigrants in France, we explore the distribution of grandchild care across offspring and the impact of this transfer on the labour supply of the mother. Our results indicate that grandchild care is spread unequally across siblings, and this inequality is driven more strongly by better labour market potential than by weaker financial status of the recipient. There is further evidence that even after accounting for potential endogeneity and unobserved heterogeneity, grandchild care has a positive impact on the labour supply of the mother. The pattern of intergenerational time transfers differs across people with different national and religions backgrounds.  相似文献   
955.
Analysis reported here examined youth in residential group home placements in order to better understand how sexual behaviors, drug use, and environmental experiences differ by race and gender subgroups. Data were collected from 336 youth aged 14–21 residing in one of 41 group homes in Maryland. Chi square and logistic regression analyses were done to determine differences on study variables among the race-gender groupings. Results demonstrate not only significant health concerns overall but notable differences were also found between race-gender subgroups. Findings suggest that found race-gender subgroup differences might be informative for tailoring programming for youth of residential group home settings.  相似文献   
956.
This paper provides a review and synthesis of research literature on the effects of shift work on workers’ physical health, mental health/well-being, and family life. The focus is on current knowledge, unanswered questions, and new directions for future research. The selection of research literature is guided by a general conceptual framework that identifies predictor variables, moderating variables, and outcome variables. The paper concludes with a discussion of the variables that should be incorporated into an agenda for future research.  相似文献   
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959.
This paper attempts to empirically investigate the link between institutional quality and economic performance in a group of 72 countries during 1980–2001, using dynamic panel data analysis. Five institutional indicators that represent the overall institutional infrastructures of an economy are employed, namely corruption, rule of law, bureaucracy, repudiation of contracts and risk of expropriation. The empirical results demonstrate that institutions’ variables are statistically significant determinants of economic performance. The findings also suggest that the effects of institutional quality vary according to the level of economic development, where institutions are more responsive in the low-income and middle-income countries. In terms of specific effect of institutional development, the results reveal that the higher level of rule of law is most potent in delivering long-run economic benefits.  相似文献   
960.
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