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   13105篇
  免费   401篇
  国内免费   15篇
管理学   1604篇
民族学   80篇
人才学   1篇
人口学   1146篇
丛书文集   143篇
理论方法论   1220篇
综合类   690篇
社会学   6979篇
统计学   1658篇
  2023年   70篇
  2021年   108篇
  2020年   208篇
  2019年   256篇
  2018年   330篇
  2017年   478篇
  2016年   326篇
  2015年   265篇
  2014年   312篇
  2013年   2052篇
  2012年   480篇
  2011年   464篇
  2010年   392篇
  2009年   328篇
  2008年   401篇
  2007年   413篇
  2006年   417篇
  2005年   361篇
  2004年   285篇
  2003年   252篇
  2002年   268篇
  2001年   339篇
  2000年   281篇
  1999年   273篇
  1998年   200篇
  1997年   169篇
  1996年   158篇
  1995年   172篇
  1994年   159篇
  1993年   163篇
  1992年   185篇
  1991年   186篇
  1990年   183篇
  1989年   159篇
  1988年   167篇
  1987年   192篇
  1986年   147篇
  1985年   157篇
  1984年   175篇
  1983年   151篇
  1982年   151篇
  1981年   121篇
  1980年   111篇
  1979年   122篇
  1978年   95篇
  1977年   79篇
  1976年   93篇
  1975年   109篇
  1974年   84篇
  1972年   62篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
911.
912.
Public opinion surveys purport to express the public's opinion. The literature on survey techniques has, however, recognized various potential limitations to the validity of survey results. While improved survey methodology may reduce statistical bias and improve validity, it cannot avoid the implicit weighting of preferences. This normative aspect of surveying has often been unrecognized or disguised as a purely technical matter. Such things as sample selection, choice of survey instrument and the method of aggregating results will each contribute to a pattern of preference weights. Several common survey techniques are examined in this light. It is proposed that no single ‘correct’ method of preference aggragation exists. Increased public recognition of, and debate on this normative aspect of surveying is recommended.  相似文献   
913.
914.
915.
916.
Twenty-four-hour recall data from the Continuing Survey of Food Intake by Individuals (CSFII) are frequently used to estimate dietary exposure for risk assessment. Food frequency questionnaires are traditional instruments of epidemiological research; however, their application in dietary exposure and risk assessment has been limited. This article presents a probabilistic method of bridging the National Health and Nutrition Examination Survey (NHANES) food frequency and the CSFII data to estimate longitudinal (usual) intake, using a case study of seafood mercury exposures for two population subgroups (females 16 to 49 years and children 1 to 5 years). Two hundred forty-nine CSFII food codes were mapped into 28 NHANES fish/shellfish categories. FDA and state/local seafood mercury data were used. A uniform distribution with minimum and maximum blood-diet ratios of 0.66 to 1.07 was assumed. A probabilistic assessment was conducted to estimate distributions of individual 30-day average daily fish/shellfish intakes, methyl mercury exposure, and blood levels. The upper percentile estimates of fish and shellfish intakes based on the 30-day daily averages were lower than those based on two- and three-day daily averages. These results support previous findings that distributions of "usual" intakes based on a small number of consumption days provide overestimates in the upper percentiles. About 10% of the females (16 to 49 years) and children (1 to 5 years) may be exposed to mercury levels above the EPA's RfD. The predicted 75th and 90th percentile blood mercury levels for the females in the 16-to-49-year group were similar to those reported by NHANES. The predicted 90th percentile blood mercury levels for children in the 1-to-5-year subgroup was similar to NHANES and the 75th percentile estimates were slightly above the NHANES.  相似文献   
917.
In evaluating family preservation services, it is important not only to study the service outcomes and the family characteristics, but also what actually happens during the treatment. This requires a program model. This article describes how a program model works, prescribes how workers should carry it out, and describes how researchers should measure the program's characteristics. The authors use data from Families First in The Netherlands to test the model. Results show that the method of the program meets the specified characteristics. The results are important for treatment, policy, education, and evaluation research.  相似文献   
918.
This study describes depressive symptoms among caregivers following bereavement and connects these trajectories to earlier features of caregiving using life course and stress process theory. Data are from a six-wave longitudinal survey (five years) of spouses and adult children caring for someone with Alzheimer's Disease. The analytic subsample (N = 291) is defined by death of the care-recipient after the baseline interview. A latent class mixture model is used to identify distinctive clusters of depressive symptoms over time. Of the four trajectories identified, three represent stable symptom levels over time, with two-thirds being repeatedly symptomatic (medium symptom levels), compared to two smaller groups of repeatedly asymptomatic (effectively absent of symptoms) and repeatedly distressed (severe symptoms). In contrast, about one in five caregivers experiences improved emotional well-being over time, the temporarily distressed, who progress from severe to moderate symptom levels. Caregivers with few symptoms before bereavement tend to maintain these states afterwards, but emotionally distressed caregivers tend to become more distressed. Role overload before bereavement substantially increases the odds of following an unfavorable trajectory afterwards, whereas self-esteem and socioemotional support play protective roles. These results demonstrate that caregivers are not uniform in their emotional responses to bereavement, but follow several distinct trajectories. These trajectories are linked to their previous experiences as caregivers, in particular exposure to stressors and access to resources. These findings suggest that intervention during caregiving may facilitate adaptation following death of a loved one.  相似文献   
919.
This research project examined the individual and combined effectiveness of an HIV prevention workshop and a free condom distribution program in four high schools in Tijuana, Mexico. Adolescents (N = 320) completed baseline measures on sexual practices and theoretical correlates and participated in a two-part study. In Study 1, students were randomly assigned to an HIV prevention workshop or a control condition, with a 3-month follow-up assessment. Results indicate three significant workshop benefits regarding HIV transmission by altering sexual initiation, access to condoms, and traditional beliefs regarding condoms. In Study 2, we set up a condom distribution program at two of the participating schools, and students completed a 6-month follow-up assessment. Results indicate that exposure to the workshop followed by access to the condom distribution program yielded two beneficial results for reducing HIV transmission: moderating sexual initiation and increasing condom acquisition. Access to the condom distribution program alone had no effects on behavioral and psychosocial correlates of HIV transmission. We discuss implications of these results.  相似文献   
920.
This research is based on in-depth ethnographic interviews and focus groups with 88 African American family caregivers from various regions of the United States during a stressful time in their family development--caregiving at the end-of-life--and the grieving during the aftermath. The study employed a stratified purposeful sampling strategy. Subjects were African Americans from the Northern, Southern, and Midwestern United States. Formal care is complicated by the distrust that many African Americans hold toward the health care system, which has resulted from years of exclusion, racism and discrimination. The findings highlight the importance of hearing from African American families to gain an understanding of what services, including family therapy and other psychotherapy, they will need during this process.  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