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191.
Exotic plant species very often comprise a large proportion of urban floras. Because herbivorous insects depend on the presence of suitable host plants to maintain their populations, it is imperative to elucidate the relative importance of native and exotic hosts to understand the response of herbivorous guilds to urbanization. By using a plant-herbivore system composed of Asteraceae hosts and flower-head endophagous insects, we investigated whether the diversity and composition of herbivorous insects differs between native and exotic host-plant species in an urban environment. Although we found only seven exotic Asteraceae among the 30 species recorded, the overall abundance of exotics was considerably greater than that of native host plants. Overall, the exotic host species supported a small subset of the herbivore assemblage found on the native ones. The number of herbivore species per host species was significantly higher among the native plants, but we did not find a difference in herbivore abundance. Moreover, the higher taxonomic composition of herbivores on exotic Asteraceae was reduced, being composed of only three genera and two families from a total of 16 genera and six families of herbivores. These results provide support for the idea that plants outside of their original geographic distribution have lower loads of enemies than phylogenetically related native species. Our findings indicate that native host plants in urban areas play a critical role in supporting the native herbivorous insect fauna.  相似文献   
192.
Neighborhoods are important places of aging and meaningful contexts of life for many older people. The overall aim of this study was to explore the public life of older people aging in place in order to understand neighborhoods as the material places where public life occurs, networks as the social places of public life, and to examine how these neighborhoods and networks influence the experience of aging and wellbeing. Adopting a friendly visiting methodology, data was collected over an 8-month period using participant observation, visual methods and an innovative interview technique called the “go along method”. Data were analyzed using grounded theory and a coding strategy that integrated textual, visual, and auditory data. Results provide insights into the micro-territorial functioning of neighborhoods and highlight third places and transitory zones as significant sites for older residents. Embedded within these places is a natural neighborhood network — a web of informal relationships and interactions that enhance well being and shape the everyday social world of older adults aging in place.  相似文献   
193.
The highly masculine sex ratio in India has increased substantially in the twentieth century, in contrast to most other countries in the world. Competing arguments alternatively posit under-enumeration, highly masculine sex ratios at birth, or excess female mortality throughout the life course as the factors underlying the level of the overall sex ratio; these arguments have not been resolved. Based on population projections that simulate population dynamics, our findings show that small differences in mortality at young ages, persisting over a long period, as well as a sex ratio at birth of 106 males per 100 females, result in a highly masculine population sex ratio.  相似文献   
194.
Data from a two-wave survey of low-income families in Boston, Chicago, and San Antonio are used to replicate recent reports of a modest increase in the number of low-income children living in two-adult families and to analyze the increase. We find that most of the increase occurred through the addition of a man other than the biological father to the household and that more of it occurred through cohabitation than through marriage. Moreover, across the two waves, cohabiting and marital unions were highly unstable. We review research on stepfamilies and on instability in childrens living arrangements, and we conclude that the kinds of two-adult families being formed in these low-income central-city neighborhoods may not benefit children as much as policy-makers hope. In addition, we investigate the associations between marital and cohabiting transitions, on the one hand, and transitions into and out of Temporary Assistance to Needy Families (TANF) receipt, employment, and Earned Income Tax Credit (EITC) usage between the two waves on the other. We find that marital transitions are related to TANF and employment transitions but that cohabiting transitions are not. We suggest that low-income mothers may view marriage as more of an economic partnership than cohabitation and may expect more of an economic contribution from a husband than from a cohabiting partner.  相似文献   
195.
Objective. This article seeks to explain why Latino children maintain some knowledge of their native language even though past research has consistently supported the view that non‐English‐language use rarely lasts past the third generation. I argue that family context, in addition to assimilation characteristics, plays an important role in determining their language situation. Method. I use both logistic regression and tobit regression, as well as data from the 1988 National Education Longitudinal Study, to examine the use and proficiency of Spanish among Latino children. Results. The results demonstrate that language and family context strongly influence Spanish usage and proficiency for Latino children, regardless of generational status. Conclusions. These findings reveal a relationship between assimilation, family, and language that can have important implications for the future academic and economic success of Latino children.  相似文献   
196.
During the 1990s, the Swedish welfare state was declared by some to be in a “crisis”, due to both financial strain and loss of political support. Others have argued that the spending cuts and reforms undertaken during this period did slow down the previous increase in social spending, but left the system basically intact. The main argument put forward in this article is that the Swedish welfare state has been and is still undergoing a transforming process whereby it risks losing one of its main characteristics, namely the belief in and institutional support for social egalitarianism. During the 1990s, the public welfare service sector opened up to competing private actors. As a result, the share of private provision grew, both within the health‐care and primary education systems as well as within social service provision. This resulted in a socially segregating dynamic, prompted by the introduction of “consumer choice”. As will be shown in the article, the gradual privatization and market‐orientation of the welfare services undermine previous Swedish notions of a “people's home”, where uniform, high‐quality services are provided by the state to all citizens, regardless of income, social background or cultural orientation.  相似文献   
197.
198.
Allocating projects to project managers (PM) is a crucial decision in project management. Choosing the PM must be undertaken in a structured way, and thereby take into account the needs of the project and the PM’s competences and availability. The proposed model optimises the total time that PMs have available and takes into account the constraint of the switchover time loss within the mathematical programming. It model is part of a three-stage approach where: (1) projects are sorted using a multicriteria approach; (2) PMs are sorted using a multicriteria approach; and (3) the final allocation to intra-classes of projects is made using the optimisation model. This proposal contributes to aiding decision-makers involved in allocating projects: by respecting the limit of the time that PMs have available, or by extrapolating PMs’ available hours in which case overtime will have to be used. The model is applied in a Brazilian Energy Company.  相似文献   
199.
The purpose of this paper is to develop a Bayesian approach for log-Birnbaum–Saunders Student-t regression models under right-censored survival data. Markov chain Monte Carlo (MCMC) methods are used to develop a Bayesian procedure for the considered model. In order to attenuate the influence of the outlying observations on the parameter estimates, we present in this paper Birnbaum–Saunders models in which a Student-t distribution is assumed to explain the cumulative damage. Also, some discussions on the model selection to compare the fitted models are given and case deletion influence diagnostics are developed for the joint posterior distribution based on the Kullback–Leibler divergence. The developed procedures are illustrated with a real data set.  相似文献   
200.
Cities facing a continued and prolonged process of population decline require innovative urban regeneration policies complementary to growth-oriented policies. Losing inhabitants involves a decrease in economic activity and social capital. Therefore citizens’ participation in defining policies to cope with population decline is being increasingly advocated. This research focused on four shrinking cities of Portugal to capture residents’ knowledge about the strengths and weaknesses of their city of residence as well as the policies and actions they prioritized for dealing with the population decline. The responses from 701 questionnaires show that economic revival policies as well as safety and accessibility policies were preferred. To put these policies into action, the recovery of industrial activity, the creation of business incubators, an improvement in law enforcement, and public lighting were ranked as top priorities. Rank-ordered logistic regression models were used to understand which variables influenced the residents’ rankings. We found that the evaluation of the city's characteristics impact the ranking of the policies and actions. Hence, residents show a high level of coherence when engaging in a discussion at the level of policy-making. Therefore, the findings support residents’ involvement in decision-making processes regarding urban regeneration in shrinking cities.  相似文献   
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