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   1339篇
  免费   82篇
管理学   121篇
民族学   12篇
人口学   153篇
丛书文集   10篇
理论方法论   202篇
综合类   9篇
社会学   778篇
统计学   136篇
  2023年   11篇
  2021年   12篇
  2020年   40篇
  2019年   63篇
  2018年   51篇
  2017年   81篇
  2016年   52篇
  2015年   47篇
  2014年   56篇
  2013年   277篇
  2012年   59篇
  2011年   55篇
  2010年   27篇
  2009年   24篇
  2008年   49篇
  2007年   41篇
  2006年   35篇
  2005年   39篇
  2004年   38篇
  2003年   32篇
  2002年   37篇
  2001年   26篇
  2000年   22篇
  1999年   18篇
  1998年   14篇
  1997年   11篇
  1996年   19篇
  1995年   16篇
  1994年   12篇
  1993年   8篇
  1992年   7篇
  1991年   13篇
  1990年   6篇
  1989年   8篇
  1988年   7篇
  1987年   8篇
  1986年   4篇
  1985年   5篇
  1984年   11篇
  1983年   9篇
  1982年   6篇
  1981年   5篇
  1980年   7篇
  1979年   4篇
  1978年   7篇
  1977年   10篇
  1976年   7篇
  1975年   3篇
  1974年   6篇
  1963年   2篇
排序方式: 共有1421条查询结果,搜索用时 0 毫秒
21.
GM Foods and the Misperception of Risk Perception   总被引:3,自引:0,他引:3  
Public opposition to genetically modified (GM) food and crops is widely interpreted as the result of the public's misperception of the risks. With scientific assessment pointing to no unique risks from GM crops and foods, a strategy of accurate risk communication from trusted sources has been advocated. This is based on the assumption that the benefits of GM crops and foods are self-evident. Informed by the interpretation of some qualitative interviews with lay people, we use data from the Eurobarometer survey on biotechnology to explore the hypothesis that it is not so much the perception of risks as the absence of benefits that is the basis of the widespread rejection of GM foods and crops by the European public. Some respondents perceive both risks and benefits, and may be trading off these attributes along the lines of a rational choice model. However, for others, one attribute-benefit-appears to dominate their judgments: the lexicographic heuristic. For these respondents, their perception of risk is of limited importance in the formation of attitudes toward GM food and crops. The implication is that the absence of perceived benefits from GM foods and crops calls into question the relevance of risk communication strategies for bringing about change in public opinion.  相似文献   
22.
We propose a multiple imputation method to deal with incomplete categorical data. This method imputes the missing entries using the principal component method dedicated to categorical data: multiple correspondence analysis (MCA). The uncertainty concerning the parameters of the imputation model is reflected using a non-parametric bootstrap. Multiple imputation using MCA (MIMCA) requires estimating a small number of parameters due to the dimensionality reduction property of MCA. It allows the user to impute a large range of data sets. In particular, a high number of categories per variable, a high number of variables or a small number of individuals are not an issue for MIMCA. Through a simulation study based on real data sets, the method is assessed and compared to the reference methods (multiple imputation using the loglinear model, multiple imputation by logistic regressions) as well to the latest works on the topic (multiple imputation by random forests or by the Dirichlet process mixture of products of multinomial distributions model). The proposed method provides a good point estimate of the parameters of the analysis model considered, such as the coefficients of a main effects logistic regression model, and a reliable estimate of the variability of the estimators. In addition, MIMCA has the great advantage that it is substantially less time consuming on data sets of high dimensions than the other multiple imputation methods.  相似文献   
23.
Urban-associated changes can have immediate or long-term consequences on animal populations. Such changes may be assessed through parasite prevalence and abundance in wildlife hosts, as urbanization can influence parasitism and disease transmission in wildlife. Snakes are widespread and diverse vertebrates that often persist in urban environments; however, parasitism of snakes in urban environments has yet to be studied, leaving the roles of snakes in parasite transmission uncharacterized. Field ecology, microscopy, molecular techniques, and geographic information science (GIS) were integrated to characterize parasitism of snakes in an urban old-growth forest park. The species, sex, mass, length, location, and prevalence of ecto-, hemo-, and fecal parasites were determined for 34 snakes of 6 species. Ectoparasites (mite), hemoparasites (Hepatozoon spp.), and fecal parasites (Entamoeba spp., Trichomonas spp., Strongloides spp., and an unidentified helminth) were detected in snakes and 64.7?% of snakes were infected by at least one of these parasites. Parasite infections were generally not related to the sex, age, or body condition of snakes. The locations of infected snakes were used to produce risk maps indicating where parasite prevalence is predicted to be greatest. The analysis of these maps indicated that snakes with fecal parasites were closer than non-infected snakes to the edge of the forest. This study confirms that snakes may be important parasite hosts or reservoirs in parasite transmission pathways in urban environments and it provides an integrative multidisciplinary approach that may be used to monitor parasitism dynamics in other urban wildlife areas.  相似文献   
24.
Early in development, children explore and combine objects in increasingly complex ways. One manual skill, object construction, represents a major shift in how objects are explored relative to other objects. Despite recent connections with cognitive functioning such as spatial skills, the development of object construction ability has rarely been studied and its trajectory has not been adequately described. The purpose of this study was to describe the development of three types of object construction (stacking, nesting, and affixing) across 5 monthly infant visits and 7 monthly toddler visits using a longitudinal design and a large sample size. Infants (10–14 months, = 131) and toddlers drawn from the infant sample (18–24 months, = 65) were given sets of age‐appropriate toys each of which elicited at least one type of constructive play. We described success at different construction tasks and identified trends for construction skill for infant and toddler development using multilevel modeling. We found that each of the three construction actions developed in unique ways across the 10‐ to 24‐month period. Infant construction skill predicted the development of toddler skill, but toddler construction skill diverged from infant trajectories. We discuss the role of combination strategies in the development of object construction skill and how object construction could be related to other domains of development.  相似文献   
25.
This study examined the role of depressive symptoms, acute intoxication, and risk rationale in men’s use of condom use resistance (CUR) tactics in an experimental study. Participants included 313 heterosexual male, nonproblem drinkers, ages 21 to 30. Participants were randomized to one of four beverage conditions: no alcohol, placebo, low (.04%) alcohol dose, or high (.08%) alcohol dose. They read an eroticized scenario depicting a consensual sexual encounter with a female partner who requested a condom to prevent either pregnancy or sexually transmitted infections (STIs) (risk rationale) and then indicated their intentions to use 10 different CUR tactics. Hypotheses related to the pharmacological, dosage, and expectancy effects of alcohol were tested in a generalized linear model. In intoxicated (.04% and .08%) men who were given a pregnancy risk rationale, depressive symptoms were associated with stronger intentions to use CUR tactics than in sober (control and placebo) men. Men who received a high alcohol dose (.08%) and who were given a pregnancy risk rationale reported higher intentions to use CUR tactics than those who received a lower alcohol dose (.04%). Findings suggest that the pharmacological effects of alcohol on men’s likelihood to resist condoms vary by the saliency of the risk rationale and mood-related variables.  相似文献   
26.
This article examines how childhood innocence is taken up in (92) memories of undergraduate students across four sites in the US and Canada. Drawing from Foucault's theory of discourse, we examine how three themes—innocence as not knowing, innocence as being provided for, and loss of innocence as exposure to adversity—construct childhood as the absence of conflict, which perpetuates the myth of an innocence/experience binary and encourages a deficit perspective of childhood. These findings contribute to teacher education and childhood studies by highlighting the importance of interrogating adult memories in order to disrupt normative assumptions about children.  相似文献   
27.
Jurisdiction-stripping has long been a questionable component of Congress's power to supervise the judiciary's policymaking role. It has gained notoriety in recent debates surrounding judicial involvement in areas including religious establishment and privacy issues such as abortion and same-sex marriage. Most scholarship equates the advocacy of jurisdiction-stripping measures with symbolic position-taking that is unmotivated by the goal of traditional policy success. This work, a quantitative case study of the first such measure to pass the House of Representative since Reconstruction, seeks to isolate legislative motivations for exerting jurisdictional controls against the Supreme Court. Legislators’ votes on this measure were multifaceted. While those decisions were guided in part by the symbolic and representational considerations that traditionally underlie the advocacy of such legislation, there is also evidence more substantive motivations played a part. The study highlights the evolving objectives of jurisdiction-stripping's advocates and, more broadly, Congress's objectives vis-à-vis the courts.  相似文献   
28.
29.
To recover a low-rank structure from a noisy matrix, truncated singular value decomposition has been extensively used and studied. Recent studies suggested that the signal can be better estimated by shrinking the singular values as well. We pursue this line of research and propose a new estimator offering a continuum of thresholding and shrinking functions. To avoid an unstable and costly cross-validation search, we propose new rules to select two thresholding and shrinking parameters from the data. In particular we propose a generalized Stein unbiased risk estimation criterion that does not require knowledge of the variance of the noise and that is computationally fast. A Monte Carlo simulation reveals that our estimator outperforms the tested methods in terms of mean squared error on both low-rank and general signal matrices across different signal-to-noise ratio regimes. In addition, it accurately estimates the rank of the signal when it is detectable.  相似文献   
30.
Abstract

This case study focuses on user research that was conducted to enhance our users’ ebook discovery experience. We took an outward-facing approach by seeking the users’ perspectives. We wanted to know: How do users find ebooks? How do they perceive multiple records for the same title? Would users find additional metadata useful, such as download availability, file format, and chapter titles? We coordinated guerilla usability testing in our library lobby, inspired by low-overhead, high-impact user experience work at other academic libraries. The resulting data gave us a much-needed new perspective of ebook usage that supplements what we already know from our day-to-day work.  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