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   28278篇
  免费   781篇
  国内免费   1篇
管理学   4132篇
民族学   125篇
人才学   6篇
人口学   2656篇
丛书文集   125篇
教育普及   2篇
理论方法论   2651篇
现状及发展   1篇
综合类   546篇
社会学   13398篇
统计学   5418篇
  2023年   134篇
  2021年   167篇
  2020年   395篇
  2019年   561篇
  2018年   650篇
  2017年   901篇
  2016年   722篇
  2015年   542篇
  2014年   675篇
  2013年   4591篇
  2012年   959篇
  2011年   867篇
  2010年   677篇
  2009年   583篇
  2008年   708篇
  2007年   683篇
  2006年   663篇
  2005年   722篇
  2004年   631篇
  2003年   638篇
  2002年   680篇
  2001年   745篇
  2000年   721篇
  1999年   652篇
  1998年   499篇
  1997年   429篇
  1996年   448篇
  1995年   416篇
  1994年   414篇
  1993年   419篇
  1992年   479篇
  1991年   461篇
  1990年   406篇
  1989年   395篇
  1988年   409篇
  1987年   374篇
  1986年   346篇
  1985年   407篇
  1984年   379篇
  1983年   352篇
  1982年   301篇
  1981年   261篇
  1980年   230篇
  1979年   267篇
  1978年   259篇
  1977年   220篇
  1976年   186篇
  1975年   214篇
  1974年   169篇
  1973年   155篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.
992.
This qualitative study describes environmental supports and barriers to physical activity in an older adult sample drawn from low- and high-walkable neighborhoods. Thirty-seven individuals age 55 and over were recruited and answered open-ended survey questions, with a subsample invited back to partake in a semistructured interview. Content analysis identified categories and themes linking perceptions of neighborhood-environment characteristics to activity. Emerging categories and themes did not differ across neighborhood walkability, so results are presented for both groups combined. Infrastructure was the most common category identified to encourage activity, specifically, well-maintained sidewalks, bike paths or lanes, and traffic control. Other categories of land use, landscape, and aesthetics were reported. Poorly maintained or missing sidewalks, crosswalks, bike paths or lanes, and traffic safety were categories that discouraged activity. In conclusion, the information obtained is helpful in solidifying which environmental characteristics are important to measure as they relate to activity behavior in an older adult population.  相似文献   
993.
The Physical Activity Questionnaire for Elderly Japanese (PAQ-EJ) is a self-administered physical activity questionnaire for elderly Japanese; the authors report here on its repeatability and direct and indirect validity. Reliability was assessed by repeat administration after 1 month. Direct validation was based on accelerometer data collected every 4 s for 1 month in 147 individuals age 65-85 years. Indirect validation against a 10-item Barthel index (activities of daily living [ADL]) was completed in 3,084 individuals age 65-99 years. The test-retest coefficient was high (r = .64-.71). Total and subtotal scores for lower (transportation, housework, and labor) and higher intensity activities (exercise/sports) were significantly correlated with step counts and durations of physical activity <3 and >or=3 METs (r = .41, .28, .53), respectively. Controlling for age and ADL, scores for transportation, exercise/sports, and labor were greater in men, but women performed more housework. Sex- and ADL- or age-adjusted PAQ-EJ scores were significantly lower in older and dependent people. PAQ-EJ repeatability and validity seem comparable to those of instruments used in Western epidemiological studies.  相似文献   
994.
Is Work-Family Policy Use Related to the Gendered Division of Housework?   总被引:6,自引:6,他引:0  
Researchers have proposed that work-family policy use may either reinforce or challenge the existing gendered division of labor within couples, but results from prior studies have been inconclusive. Using data from a regional survey of work and family life, we extend this research by focusing on how housework is divided within couples and by differentiating between traditionally female- and male- typed housework tasks. Results show that among dual-earning women, policy use is not related to share of female- or male-typed tasks. Among dual-earning men, policy use is positively related to share of female-typed tasks and negatively related to share of male-typed tasks. These findings suggest that work-family policy use does not reinforce the gendered division of housework.
Mary C. NoonanEmail:
  相似文献   
995.
This study investigates the impact of personal finance education delivered in high school and college. Outcomes of interest were investment knowledge and household savings rates measured years after the financial education was delivered. A web-based survey with questions about participation in financial education, financial experiences, income and inheritances, and demographic characteristics was administered to 1,039 alumni from a large midwestern university. Participation in a college level personal finance course was associated with higher levels of investment knowledge. Experience with financial instruments appeared to explain more of the variance in both investment knowledge and savings rates. No significant relationship between taking a high school course and investment knowledge was found. Financial experiences were found to be positively associated with savings rates.
Garrett CravenerEmail:
  相似文献   
996.
Using a spatially extensive urban database constructed from the Maryland Biological Stream Survey (MBSS), we describe the relationships of nutrients in small-order streams to eight defined categories of percent catchment urbanization, correlations between chloride and conductivity in urban streams, and relationships between nutrients and chloride with two Maryland-specific indices of biotic integrity for benthic macroinvertebrates and fish assemblages. Stream nutrients become elevated with increasing percent catchment urbanization, followed by increases in all four measured nitrogen species and total phosphorus at catchment urbanization levels greater than 10%. There was a strong collinear relationship (r 2 = 0.90) between chloride and conductivity (trimeans) across all eight urbanization classes, where Cl (mg/L) = −0.397 + 0.188*conductivity (μS/cm). Critical values for all water quality parameters with the two Maryland biological indices were derived using quantile regression, with significant regressions developed for 11 of 16 water quality parameters and the two biotic indices. For nitrate (NO3-N), the critical thresholds between fair and poor stream quality for the two Maryland biological indices were 0.83 mg/L (benthic macroinvertebrate assemblages) and 0.86 mg/L (fish assemblages). Increasing stream nutrient and chloride levels, associated with widespread catchment urbanization intensity, now affect many small streams in Maryland, with implications for decreasing water quality in major tributaries and the Chesapeake Bay.  相似文献   
997.
998.
The indications for hormone replacement therapy (HRT) in postmenopausal women is the treatment of climacteric symptoms and the prevention of osteoporosis. Women with systemic lupus erythematosus (SLE) are more likely to have a premature menopause, osteoporosis and cardiovascular disease. HRT can induce SLE flares and cardiovascular or venous thromboembolic events. Therefore it should not be used in women with active disease or those with antiphospholipid (aPL) antibodies. In general, it should be used only for patients without active disease, a history of thrombosis or aPL antibodies. Non-oral administration of estrogen is recommended because of its lesser effect on coagulation. With regard to the progestogen, progesterone or pregnane derivatives are preferred. Otherwise, non-estrogen-based strategies should be used.  相似文献   
999.
Card and Krueger's (1995) difference-in-difference study of the 1990-1991 federal minimum wage hikes compared states by the proportion of workers directly affected by the minimum wage. They found "no evidence that the increase in the minimum wage significantly lowered teenage employment rates more in highly affected states" and they concluded the minimum wage did not reduce employment. Their paper was highly influential and convinced many that the minimum wage did not reduce employment. However, when I apply their model to the 1996-1997 federal minimum wage hike, I find that increases in the minimum wage significantly lowered teenage employment rates more in highly affected states. Using Card and Krueger's interpretation, this implies the minimum wage did reduce teenage employment.  相似文献   
1000.
We test the human capital interpretation of the experience-earnings profile. Does the upward sloping portion of the experience-earnings profile reflect on-the-job training which in turn causes the experience-productivity profile to slope upwards, or do purely contractual factors determine the nature of life-cycle earnings. Herein, we provide additional evidence on the relationship between productivity and earnings by examining earnings differentials in the UK academic labor market for economists. Using a test first suggested by Mincer, we find that the empirical results are consistent with human capital theory. We find that, although the positive relationship between earnings and experience persists when individual productivity measures are included in the salary equations for lecturers and senior lecturers, the positive relationship becomes statistically insignificant when the same productivity measures are included in the salary equations for professors. For lecturers and senior lecturers, the experience-salary profile properly reflects the structure of the national pay scale rather than variations in individual research productivity. At the professor level, where individual salaries are not determined by a pay scale, the data support the human capital explanation of the positive experience-earnings profile.
Robert J. NewmanEmail:
  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