首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   39179篇
  免费   536篇
  国内免费   1篇
管理学   5711篇
民族学   210篇
人才学   2篇
人口学   5134篇
丛书文集   136篇
教育普及   3篇
理论方法论   3129篇
现状及发展   2篇
综合类   663篇
社会学   18194篇
统计学   6532篇
  2023年   165篇
  2021年   187篇
  2020年   446篇
  2019年   620篇
  2018年   2203篇
  2017年   2438篇
  2016年   1735篇
  2015年   572篇
  2014年   755篇
  2013年   4817篇
  2012年   1282篇
  2011年   1942篇
  2010年   1637篇
  2009年   1336篇
  2008年   1448篇
  2007年   1634篇
  2006年   669篇
  2005年   893篇
  2004年   876篇
  2003年   771篇
  2002年   733篇
  2001年   778篇
  2000年   780篇
  1999年   682篇
  1998年   506篇
  1997年   463篇
  1996年   481篇
  1995年   455篇
  1994年   397篇
  1993年   414篇
  1992年   482篇
  1991年   439篇
  1990年   411篇
  1989年   435篇
  1988年   420篇
  1987年   370篇
  1986年   374篇
  1985年   425篇
  1984年   409篇
  1983年   378篇
  1982年   321篇
  1981年   266篇
  1980年   253篇
  1979年   318篇
  1978年   261篇
  1977年   238篇
  1976年   207篇
  1975年   225篇
  1974年   184篇
  1973年   177篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
921.
Psychometric growth curve modeling techniques are used to describe a person’s latent ability and how that ability changes over time based on a specific measurement instrument. However, the same instrument cannot always be used over a period of time to measure that latent ability. This is often the case when measuring traits longitudinally in children. Reasons may be that over time some measurement tools that were difficult for young children become too easy as they age resulting in floor effects or ceiling effects or both. We propose a Bayesian hierarchical model for such a scenario. Within the Bayesian model we combine information from multiple instruments used at different age ranges and having different scoring schemes to examine growth in latent ability over time. The model includes between-subject variance and within-subject variance and does not require linking item specific difficulty between the measurement tools. The model’s utility is demonstrated on a study of language ability in children from ages one to ten who are hard of hearing where measurement tool specific growth and subject-specific growth are shown in addition to a group level latent growth curve comparing the hard of hearing children to children with normal hearing.KEYWORDS: Bayesian hierarchical models, psychometric modeling, language ability, growth curve modeling, longitudinal analysis  相似文献   
922.
This paper presents an inventory problem related to the one-period stochastic inventory (or “newsboy”) problem. In this problem, the firm has to decide how much product to order to meet a random one-period demand. The version of the problem presented is novel in two respects. First, demand is explicitly permitted to be negative, and second, the penalty (or shortage) cost is assumed to be independent of the magnitude of the shortage. This situation is shown to change the form of the cost function and to complicate the determination of optimal policies. The form of the optimal policy is developed, and two example problems are presented in some detail.  相似文献   
923.
While it is well known that the widowed suffer increased mortality risks, the mechanism of this survival disadvantage is still under investigation. In this article, we examine the quality of health care as a possible link between widowhood and mortality using a unique data set of 475,313 elderly couples who were followed up for up to nine years. We address whether the transition to widowhood affects the quality of care that individuals receive and explore the extent to which these changes mediate the elevated mortality hazard for the widowed. We analyze six established measures of quality of health care in a fixed-effect framework to account for unobserved heterogeneity. Caregiving and acute bereavement during the transition to widowhood appear to distract individuals from taking care of their own health care needs in the short run. However, being widowed does not have long-term detrimental effects on individuals’ ability to sustain contact with the formal medical system. Moreover, the short-run disruption does not mediate the widowhood effect on mortality. Nevertheless, long after spousal death, men suffer from a decline in the quality of informal care, coordination between formal and informal care, and the ability to advocate and communicate in formal medical settings. These findings illustrate women’s centrality in the household production of health and identify important points of intervention in optimizing men’s adjustment to widowhood.  相似文献   
924.
Obesity is considered a major cause of premature mortality and a potential threat to the longstanding secular decline in mortality in the United States. We measure relative and attributable risks associated with obesity among middle-aged adults using data from the Health and Retirement Study (1992–2004). Although class II/III obesity (BMI _ 35.0 kg/m2) increases mortality by 40% in females and 62% in males compared with normal BMI (BMI = 18.5-24.9), class I obesity (BMI = 30.0-34.9) and being overweight (BMI = 25.0-29.9) are not associated with excess mortality. With respect to attributable mortality, class II/III obesity (BMI _ 35.0) is responsible for approximately 4% of deaths among females and 3% of deaths among males. Obesity is often compared with cigarette smoking as a major source of avoidable mortality. Smoking-attributable mortality is much larger in this cohort: about 36% in females and 50% in males. Results are robust to confounding by preexisting diseases, multiple dimensions of socioeconomic status (SES), smoking, and other correlates. These findings challenge the viewpoint that obesity will stem the long-term secular decline in U.S. mortality.  相似文献   
925.
Steven Martin 《Demography》2009,46(1):203-208
This analysis joins the debate on how declines in marriage have shifted the composition of the unmarried and married populations in the United States, and how compositional shifts have affected nonmarital birth rates. Gray, Stockard, and Stone (2006) presented one model for compositional effects that Ermisch (2009) challenged with alternative statistical tests. I propose an alternative model for compositional shifts based not on theory but on observed marriage and fertility patterns. The results from this alternative model are consistent with Ermisch’s findings yet support Gray et al.’s general case that compositional effects have had an important infiuence on nonmarital birth rates.  相似文献   
926.
In this article, we analyze mortality rates of Finns born in areas that were ceded to the Soviet Union after World War II and from which the entire population was evacuated. These internally displaced persons are observed during the period 1971-2004 and compared with people born in the same region but on the adjacent side of the new border. We find that in the 1970s and 1980s, the forced migrants had mortality rates that were on par with those of people in the comparison group. In the late 1980s, the mortality risk of internally displaced men increased by 20% in relation to the expected time trend. This deviation, which manifests particularly in cardiovascular mortality, coincides with perestroika and the demise of the Soviet Union, which were events that resulted in an intense debate in civil society about restitution of the ceded areas. Because state actors were reluctant to engage, the debate declined after some few years, and after the mid-1990s, the death risk again approached the long-term trend. Our findings indicate that when internally displaced persons must adjust to situations for which appropriate coping behaviors are unknown, psychosocial stress might arise several decades after their evacuation.  相似文献   
927.
Standardization and decomposition are established and widely used demographic techniques for comparing rates and means between groups with differences in composition. The difference in rates and means has heretofore been resolved in terms of the contribution of variables to compositional effects for each variable and an overall rate effect. This study demonstrates that the resolution of differences is attainable at the categorical level for both compositional effects and rate effects. Refinements to Das Gupta’s equations yield a complete decomposition because of the additivity of categorical compositional and rate effects. Other refinements allow the decomposition of polytomous variables. Extensions to the method provide for the decomposition of the standard deviation and the multivariate index of dissimilarity.  相似文献   
928.
In this study, I examine disparities in schooling progress among children born to immigrant and U.S.-born blacks. I find that in one- and two-parent families, children born to black immigrants are less likely to fall behind in school than those born to U.S.-born blacks. In two-parent immigrant families, children born to two immigrant parents have a significant schooling advantage over children born to one immigrant parent. While children born to two immigrant parents in the wealthiest black immigrant families do better in the second generation than in the first, the reverse is observed among children in less wealthy families. These findings contribute in two ways to our understanding of the assimilation processes of children born to black immigrant parents. First, they show that there is a positive association between the number of immigrant parents in a family and children’s schooling performance. Second, they suggest that disparities in the assimilation patterns of the children of black immigrants are a likely product of the interaction between their parental characteristics and the socioeconomic circumstances of their families.  相似文献   
929.
This study aims at ascertaining how Hong Kong people perceive Hong Kong as a harmonious society. It also identifies the elements that are most conducive to social harmony in Hong Kong, so that the government could take reference when formulating new policies. 1,062 adults residents were asked to rate their perceived level of social harmony and their satisfaction with 36 items (divided into three dimensions: public governance, society, and economy, family and work) for which the research team believes would be influencing the perceived level of social harmony. Results show that the average rating of social harmony was 5.57 (out of 10), delineating a moderate level of social harmony. Subsequent multivariate factor analysis and regression analysis show that the four extracted factors (from the three dimensions) had significant impacts on the level of social harmony. These were, in order of significance: (a) public governance, (b) social solidarity and respect, (c) economy/family/work and, (d) social tolerance and progressiveness. According to the factor loadings of each significant factor, we identified four core values which we hope the government would consider when formulating new policies, as follows: (1) A Justice Government with Sincerity on Communication, (2) Mutual Support and Respect with Integrity and Dedication, (3) Dedication to One’s Job and Community by Helping the Needed and, (4) Creativity and Progressiveness with Tolerance. Implications for policy making are discussed. The study was conducted under the direction and guidance of the Fostering Social Harmony Task Force of the Hong Kong Professionals and Senior Executives Association (HKPASEA). The authors acknowledge the kind support and assistance provided by the Council Members of HKPASEA and staff members of the Centre for Corporate Governance and Financial Policy at Hong Kong Baptist University. We are also grateful to Prof. Alex Michalos and Prof. P. K. Ip for their comments and suggestions given at the International Conference on National Well-Being held in November 2006 at the National Central University, Taiwan.  相似文献   
930.
The dual model of perfectionism (Slade and Owens, Behav Modificat 22(3):372–390, 1998) is adopted to examine the influence of adaptive and maladaptive perfectionism on adolescent athlete burnout in Taiwan. Participants were 188 high school adolescent student-athletes (M = 16.48, SD = .59). They were administered the Multidimensional Inventory of Perfectionism in Sport (Stoeber et al., Pers Individ Dif 43(1):131–141, 2007) and the Chinese Athlete Burnout Questionnaire (ABQ) (Lu et al., Phys Educ J 39(3):83–94, 2006). A field longitudinal design was used. In cross-sectional analyses, hierarchical multiple regressions indicated that adaptive perfectionism negatively predicted athlete burnout while maladaptive perfectionism had an inverse relationship with burnout. However, after controlling for the initial scores of burnout, neither adaptive nor maladaptive perfectionism significantly predicted athlete burnout after a three month interval. Possible mechanisms of this relation, limitations, and practical implications are discussed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号