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821.
Urbanization and development are predicted to increase considerably in the United States over the next several decades, and
this is expected to result in large-scale habitat loss, fragmentation and loss of wildlife species. Thus, natural parks and
preserves are becomingly increasingly important in the conservation of regional biodiversity. We used mist-nets and AnabatII
acoustic detectors to survey bats in 10 national parks in the southeastern U.S. and examined the relationship between bat
community structure and development in the surrounding 5 km. We predicted that species richness would increase with park size
and that species richness and evenness would decrease with development. Species richness was not related to development or
any other landscape characteristics including park size. In contrast, species evenness declined with increasing development.
Percent Developed land in the surrounding 5 km area was the only variable that entered into the stepwise regression model.
The decrease in species evenness in the urban parks was due to the dominance of big brown bats (Eptesicus fuscus) in these parks. The percentage of big brown bats in our captures was positively related to percent Developed land in the
surrounding area. Our data suggest that urban parks may be important for conserving regional bat biodiversity. However, the
low species evenness in these parks suggests that some bat species may be susceptible to the effects of urbanization and may
be extirpated over time. Thus, management of urban as well as rural parks should strive to conserve as much bat roosting and
foraging habitat as possible. 相似文献
822.
Krzysztof J. Pelc 《Transition Studies Review》2009,16(2):343-351
What can Western powers do today to ease an eventual global power shift resulting from the rise of superpowers such as China? This paper suggests that part of the answer lies in the same power-binding institutions that allowed the US to rise post WWII without threatening its allies. Continuity in the rules of the global system during a great power transition would promote stability by reducing uncertainty, as well as the extent to which material power can be used coercively. I argue that current superpowers, the EU among them, have an interest in ensuring an equitable distribution of the gains from cooperation. While distributional issues are usually treated in normative terms, they take on very real, material meaning in the context of a great power transition. With this in mind, I look at three aspects of the current global institutional framework that would benefit from reform: international trade and aid, institutional design, and institutional proliferation. In all three cases, a more equal distribution of the gains from institutions today increases the odds that those institutional arrangements will remain in the future. 相似文献
823.
We present findings from a nonexperimental evaluation of an employment program in which both partners in young, low-income,
primarily African-American couples simultaneously participated. Mothers participating in the couples program had larger immediate
gains in employment and earnings and decreases in TANF receipt following their exit from the program relative to mothers who
received employment assistance as individuals. Fathers showed similar although weaker results. These immediate benefits appeared
to be driven by higher rates of program completion among couples’ participants. Couples in which both partners completed the
program experienced the largest quarterly earnings gains, and couples with greater earnings’ gains were more likely to still
be together one year after the program ended. Mothers’ earnings gains eroded in the two years following program completion
and many reported new pregnancies and problems with child care. We suggest directions for future programs and encourage future
studies to consider the range of mechanisms associated with a couples focus, including potential motivational benefits and
unintended consequences.
相似文献
Carolyn J. Heinrich (Corresponding author)Email: |
824.
J. Paul Grayson 《International migration (Geneva, Switzerland)》2009,47(2):33-67
Research conducted in Canada and the United States shows that the age of arrival of immigrant children, language spoken in the home, and ethno‐racial origin have consequences for English language acquisition and academic attainment. So far, however, the degree to which these factors have consequences for academic achievement at the post‐secondary level has scarcely been studied. In this study, it is found that the communication skills of university students who are the sons and daughters of immigrants, independent of length of time in Canada, are not as high as those of native‐born English‐speaking Canadians. Moreover, all else being equal, independent of length of time in the country, the university GPAs of immigrant and non‐European origin groups are generally lower than those of native‐born Canadians. Findings such as these suggest the presence of social and cultural processes at the family, community, and educational system level that continue to disadvantage identifiable groups of post‐secondary students. 相似文献
825.
826.
Although attitudes toward homosexuality have become more liberal, particularly in industrialized Western countries, there is still a great deal of variance in terms of worldwide levels of homonegativity. Using data from the two most recent waves of the World Values Survey (1999–2004, 2005–2009), this article seeks to explain this variance by means of a multilevel analysis of 79 countries. We include characteristics on the individual level, as age or gender, as well as aggregate variables linked to specificities of the nation-states. In particular, we focus on the religious denomination of a person and her religiosity to explain her attitude toward homosexuality. We find clear differences in levels of homonegativity among the followers of the individual religions. 相似文献
827.
The Demographic Promise of Expanded Female Education: Trends in the Age at First Birth in Malawi
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Monica J. Grant 《Population and development review》2015,41(3):409-438
The expansion of female education has been promoted as a way to postpone the age at first birth. In sub‐Saharan Africa, the first cohorts to benefit from policies that expanded access to education are now reaching adulthood and beginning childbearing. I investigate whether the expansion of education in Malawi, which implemented a free primary education policy in 1994 and subsequently expanded secondary schooling, has led to a later age at first birth and whether the education gradient in fertility timing has remained stable over time. Despite increases in female grade attainment over the past twenty years, the age at first birth has not changed. Using instrumental variables analysis, I find a significant negative association between grade attainment and age at first birth, suggesting that the deterioration of school quality and the shift in the age pattern of enrollment that accompanied educational expansion may have compromised the transformative potential of education. 相似文献
828.
The rise in human life expectancy has involved declines in intrinsic and extrinsic mortality processes associated, respectively, with senescence and environmental challenges. To better understand the factors driving this rise, we apply a two-process vitality model to data from the Human Mortality Database. Model parameters yield intrinsic and extrinsic cumulative survival curves from which we derive intrinsic and extrinsic expected life spans (ELS). Intrinsic ELS, a measure of longevity acted on by intrinsic, physiological factors, changed slowly over two centuries and then entered a second phase of increasing longevity ostensibly brought on by improvements in old-age death reduction technologies and cumulative health behaviors throughout life. The model partitions the majority of the increase in life expectancy before 1950 to increasing extrinsic ELS driven by reductions in environmental, event-based health challenges in both childhood and adulthood. In the post-1950 era, the extrinsic ELS of females appears to be converging to the intrinsic ELS, whereas the extrinsic ELS of males is approximately 20 years lower than the intrinsic ELS. 相似文献
829.
830.
William P. O’Hare J. Gregory Robinson Kirsten West Thomas Mule 《Population research and policy review》2016,35(5):685-704
Following every U.S. decennial census since 1960, the U.S. Census Bureau has evaluated the completeness of coverage using two different methods. Demographic analysis (DA) compares the census counts to a set of independent population estimates to infer coverage differences by age, sex, and race. The survey-based approach (also called dual system estimation or DSE) provides coverage estimates based on matching data from a post-enumeration survey to census records. This paper reviews the fundamentals of the two methodological approaches and then initially examines the results of these two methods for the 2010 decennial census in terms of consistency and inconsistency for age groups. The authors find that the two methods produce relatively consistent results for all age groups, except for young children. Consequently, the paper focuses on the results for children. Results of the 1990, 2000, and 2010 decennial censuses are shown for the overall population in this age group and by demographic detail (age, race, and Hispanic origin). Among children, the DA and DSE results are most inconsistent for the population aged 0–4 and most consistent for ages 10–17. Results also show that DA and DSE are more consistent for Black than non-Black populations. The authors discuss possible explanations for the differences in the two methods for young children and conclude that the DSE approach may underestimate the net undercount of young children due to correlation bias. 相似文献