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61.
The National Survey of Family Growth (1982) is used to examine the extent to which racial differences in premarital birth rates can be explained by differences in parents' socioeconomic status, family structure, and residential characteristics. The findings document a large diversity in premarital births within both populations. Black women from high-risk backgrounds are three times more likely to have a premarital birth than black women from low-risk backgrounds. Racial differences in premarital births arise because (1) black women are more likely to come from high-risk backgrounds and (2) black women from low-risk backgrounds are more likely to have a premarital birth than white women with similar characteristics. There are similar rates of premarital births by race among persons from high-risk backgrounds.  相似文献   
62.
    
When meta-analyzing heterogeneous bodies of literature, meta-regression can be used to account for potentially relevant between-studies differences. A key challenge is that the number of candidate moderators is often high relative to the number of studies. This introduces risks of overfitting, spurious results, and model non-convergence. To overcome these challenges, we introduce Bayesian Regularized Meta-Analysis (BRMA), which selects relevant moderators from a larger set of candidates by shrinking small regression coefficients towards zero with regularizing (LASSO or horseshoe) priors. This method is suitable when there are many potential moderators, but it is not known beforehand which of them are relevant. A simulation study compared BRMA against state-of-the-art random effects meta-regression using restricted maximum likelihood (RMA). Results indicated that BRMA outperformed RMA on three metrics: BRMA had superior predictive performance, which means that the results generalized better; BRMA was better at rejecting irrelevant moderators, and worse at detecting true effects of relevant moderators, while the overall proportion of Type I and Type II errors was equivalent to RMA. BRMA regression coefficients were slightly biased towards zero (by design), but its residual heterogeneity estimates were less biased than those of RMA. BRMA performed well with as few as 20 studies, suggesting its suitability as a small sample solution. We present free open source software implementations in the R-package pema (for penalized meta-analysis) and in the stand-alone statistical program JASP. An applied example demonstrates the use of the R-package.  相似文献   
63.
    
Extreme learning machine (ELM) has attracted attentions in pattern classification problems due to its preferences in low computations and high generalization. To overcome its drawbacks, caused by the randomness of input weights and biases, the ensemble of ELMs was proposed. The diversity of ELMs forming the ensemble was studied broadly in the literature, via using different activation functions and/or different number of hidden neurons. However, less attention was paid to aggregation mechanism in ensemble of ELMs. To speed up this aggregation process, we propose an ensemble framework for ELMs, called extreme ensemble of ELMs (EEoELMs) because of its extreme speed in ensemble process. In this framework, the input weights of each ELM are randomly pre-assigned as usual. The ELMs make use of the same/distinct activation functions to increase the diversity of classifiers and so the generalization of ensemble. The output weights of each ELM are set using Moore–Penrose inverse method. However, the aggregation mechanism in EEoELM is novel. Instead of using majority/weighted voting on the prediction results of ELMs, their output neurons are combined in a new decision/ensemble layer. The output of this layer determines the ensemble output. As the weights of this decision layer are also computed using Moore–Penrose inverse method, the ensemble is extremely fast. Experimental results on synthetic and real-world datasets indicate the acceptable classification performance of EEoELM in much less computational efforts.  相似文献   
64.
Internet Paradox Revisited   总被引:7,自引:0,他引:7  
Kraut et al. (1998) reported negative effects of using the Internet on social involvement and psychological well-being among new Internet users in 1995–96. We called the effects a "paradox" because participants used the Internet heavily for communication, which generally has positive effects. A 3-year follow-up of 208 of these respondents found that negative effects dissipated. We also report findings from a longitudinal survey in 1998–99 of 406 new computer and television purchasers. This sample generally experienced positive effects of using the Internet on communication, social involvement, and well-being. However, consistent with a "rich get richer" model, using the Internet predicted better outcomes for extraverts and those with more social support but worse outcomes for introverts and those with less support.  相似文献   
65.
The advent of thousands of Usenet groups on the Internet, covering a vast range of medical and welfare issues and ostensibly devoted to the mutual social support of participating members, has raised the potential for the development of new forms of 'virtual' health care. This article critically analyses the use by people with diabetes of one such Usenet group. It seeks to establish, first, the extent to which such a site provides some demonstrable measure of social support to its participants. This is approached by undertaking a structural analysis of the site to identify the extent of usage, and the nature of supporting interventions using a fivefold classification (instrumental, informational, esteem and social companionship and other). Second, the article attempts to identify any disparity between the lay health-knowledge in evidence and biomedical opinions proffered by the use of a panel of consultant diabetiologists. The results of the analysis suggest that the diabetes newsgroup provides an example of an active forum for largely well-informed participants who routinely use the media as an aid to the reflexive management of their medical condition. It also raises the prospect of a renegotiated relationship between medical knowledge and lay experience based upon shared learning  相似文献   
66.
The aim of this paper is to find an empirical connection between the striking increase in the use of fixed-term contracts in Spain and the observed delay in the age at marriage and maternity. Using the eight waves of individual information from the European Household Panel for Spain, we find that for men, the decision whether to get married is strongly negatively affected by holding unstable contracts or not working, relative to when an indefinite contract is held. However, for women, results suggest that holding fixed-term contracts is not a deterrent for the decision whether to get married. With respect to the decision of whether to enter into parenthood, results indicate that for all childless women, either with no partner, holding fixed-term contracts delays entry into motherhood relative to the holding of indefinite contracts. The discouragement effect is stronger for women with no partner, though.JEL classification: D1, J1  相似文献   
67.
68.
We examine the role of religion in charitable giving and find that the religious preference of both the donor and the recipient organization influence giving behavior. By exploiting a panel survey of charitable giving, we demonstrate that traditional empirical analysis on charitable giving masks important differences among donor groups. Religious giving by religious individuals is least responsive to changes in price and income, while secular giving by secular individuals has the greatest sensitivity.  相似文献   
69.
Findings are reported from a process study of an English multi-disciplinary team working with families with long standing and complex problems. The approaches and methods of the team are described and placed in the context of UK policy developments and of UK and USA research on professional practice with families facing multiple difficulties. Basic data are provided on all families referred in the first year and analysed with respect to the first 100 completed cases. A broadly ethnographic research approach is used for the observational study of the team interactions and decision-making on individual cases. For a one-third sub-sample of 33 cases, process and interim outcome data are analysed from information systematically extracted from case records. These are complemented by qualitative data from interviews with managers and caseworkers and by observation of ‘team around the family’ and professionals' meetings. The researchers conclude that the service succeeds in engaging a majority of the referred families who have been hard to reach or hard to change in the past and whose children are either ‘on the edge of care’ or likely to be significantly harmed without the provision of an intensive service. The researchers concluded that improvements were made in the life chances of children in 75% of the families. Aspects of the service identified as associated with more positive outcomes are: the allocation of two key workers (one for the child/ren and one for the parent/s); the centrality of relationship-based practice and flexibility of the approach rather than strict adherence to any particular practice model; the fact that the service is firmly embedded within the statutory children's services department, allowing for continuity of relationships with team around the family members when the intensive service ends; and flexibility about case duration and intensity.  相似文献   
70.
Social class is not often discussed or examined in‐depth in couple and family therapy research and literature even though social class shapes familial relationships and is considered an important variable in marital satisfaction. In this qualitative study, we explored the perceptions of eight couples who made lasting commitments across class lines by asking them about the impact of their social class backgrounds on their relationships. Three categories of themes emerged including: (a) differences and similarities in values and attitudes toward education, work, money, and class awareness/classism, (b) relationship issues involving families of origin, friends, and class‐based couple conflict, and (c) differences in economic resources, social capital and privileges/opportunities. Implications for assessment and treatment of couples are included.  相似文献   
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