全文获取类型
收费全文 | 952篇 |
免费 | 49篇 |
国内免费 | 6篇 |
专业分类
管理学 | 268篇 |
民族学 | 6篇 |
人才学 | 1篇 |
人口学 | 26篇 |
丛书文集 | 37篇 |
理论方法论 | 31篇 |
综合类 | 444篇 |
社会学 | 69篇 |
统计学 | 125篇 |
出版年
2024年 | 8篇 |
2023年 | 13篇 |
2022年 | 17篇 |
2021年 | 20篇 |
2020年 | 28篇 |
2019年 | 23篇 |
2018年 | 32篇 |
2017年 | 31篇 |
2016年 | 28篇 |
2015年 | 37篇 |
2014年 | 53篇 |
2013年 | 100篇 |
2012年 | 56篇 |
2011年 | 50篇 |
2010年 | 37篇 |
2009年 | 47篇 |
2008年 | 40篇 |
2007年 | 51篇 |
2006年 | 44篇 |
2005年 | 37篇 |
2004年 | 38篇 |
2003年 | 32篇 |
2002年 | 24篇 |
2001年 | 26篇 |
2000年 | 24篇 |
1999年 | 13篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有1007条查询结果,搜索用时 62 毫秒
1.
贫困表现为人的基本需要得不到满足,“富裕社会”中的贫困表现为私人生产、物质生产的过剩和公共生产、精神生产的不足。加尔布雷思认为,美国“富裕社会”中贫困的原因是不平衡的“二元经济体系”,只要实行“新社会主义”,实现“计划体系”和“市场体系”的平衡,就能解决“富裕”背后的贫困问题。由于这一设想是以不改变资本主义的经济基础为前提的,所以,只能是一种治标不治本的改良。只有扬弃经济学的“传统智慧”,建构以促进“每个人的自由发展”为目标的“全面生产”经济学,才能从根本上消除“富裕社会”中的贫困问题。 相似文献
2.
讨论线偏振光入射 ,其电矢量与入射面有夹角 (该夹角称线偏振光的振动方位角 )时 ,反射光与折射光的偏振态 ,以及在全反射条件下 ,反射光的偏振态和获得圆偏振光的条件 相似文献
3.
Mark S. Pearce Heather O. Dickinson Murray Aitkin Louise Parker 《Journal of the Royal Statistical Society. Series A, (Statistics in Society)》2002,165(3):523-548
Summary. This study investigates whether there was evidence of increasing risk of still-birth with increasing paternal exposure to ionizing radiation received during employment at the Sellafield nuclear installation before the child was conceived. A significant positive association is found between the total paternal preconceptional exposure to external ionizing radiation and the risk of still-birth (after adjustment for year of birth, social class, birth order and paternal age, odds ratio at 100 mSv 1.24 (95% confidence interval 1.04–1.45)). A summary of the principal scientific findings of this study has been published in the Lancet . This paper describes in detail the statistical methods that were used in the investigation and presents the results in full. 相似文献
4.
Children may be more susceptible to toxicity from some environmental chemicals than adults. This susceptibility may occur during narrow age periods (windows), which can last from days to years depending on the toxicant. Breathing rates specific to narrow age periods are useful to assess inhalation dose during suspected windows of susceptibility. Because existing breathing rates used in risk assessment are typically for broad age ranges or are based on data not representative of the population, we derived daily breathing rates for narrow age ranges of children designed to be more representative of the current U.S. children's population. These rates were derived using the metabolic conversion method of Layton (1993) and energy intake data adjusted to represent the U.S. population from a relatively recent dietary survey (CSFII 1994–1996, 1998). We calculated conversion factors more specific to children than those previously used. Both nonnormalized (L/day) and normalized (L/kg-day) breathing rates were derived and found comparable to rates derived using energy estimates that are accurate for the individuals sampled but not representative of the population. Estimates of breathing rate variability within a population can be used with stochastic techniques to characterize the range of risk in the population from inhalation exposures. For each age and age-gender group, we present the mean, standard error of the mean, percentiles (50th, 90th, and 95th), geometric mean, standard deviation, 95th percentile, and best-fit parametric models of the breathing rate distributions. The standard errors characterize uncertainty in the parameter estimate, while the percentiles describe the combined interindividual and intra-individual variability of the sampled population. These breathing rates can be used for risk assessment of subchronic and chronic inhalation exposures of narrow age groups of children. 相似文献
5.
Bayesian analysis of discrete time warranty data 总被引:1,自引:0,他引:1
David Stephens Martin Crowder 《Journal of the Royal Statistical Society. Series C, Applied statistics》2004,53(1):195-217
Summary. The analysis of warranty claim data, and their use for prediction, has been a topic of active research in recent years. Field data comprising numbers of units returned under guarantee are examined, covering both situations in which the ages of the failed units are known and in which they are not. The latter case poses particular computational problems for likelihood-based methods because of the large number of feasible failure patterns that must be included as contributions to the likelihood function. For prediction of future warranty exposure, which is of central concern to the manufacturer, the Bayesian approach is adopted. For this, Markov chain Monte Carlo methodology is developed. 相似文献
6.
Patrick J. Farrell Sarjinder Singh 《Australian & New Zealand Journal of Statistics》2005,47(3):375-383
In survey sampling, interest often centres on inference for the population total using information about an auxiliary variable. The variance of the estimator used plays a key role in such inference. This study develops a new set of higher‐order constraints for the calibration of estimators of variance for various estimators of the population total. The proposed strategy requires an appropriate model for describing the relationship between the response and auxiliary variable, and the variance of the auxiliary variable. It is therefore referred to as a model‐assisted approach. Several new estimators of variance, including the higher‐order calibration estimators of the variance of the ratio and regression estimators suggested by Singh, Horn & Yu and Sitter & Wu are special cases of the proposed technique. The paper presents and discusses the results of an empirical study to compare the performance of the proposed estimators and existing counterparts. 相似文献
7.
Beryllium is the strongest of the lightweight metals. Used primarily in military applications prior to the end of the Cold War, beryllium is finding new applications in many commercial products, including computers, telecommunication equipment, and consumer and automotive electronics. The use of beryllium in nondefense consumer applications is of concern because beryllium is toxic. Inhalation of beryllium dust or vapor causes a chronic lung disease in some individuals at concentrations as low as 0.01 microg/m3 in air. As beryllium enters wider commerce, it is prudent to ask what risks this might present to the general public and to workers downstream of the beryllium materials industry. We address this question by evaluating the potential for beryllium exposure from the manufacturing, use, recycle, and disposal of beryllium-containing products. Combining a market study with a qualitative exposure analysis, we determine which beryllium applications and life cycle phases have the largest exposure potential. Our analysis suggests that use and maintenance of the most common types of beryllium-containing products do not result in any obvious exposures of concern, and that maintenance activities result in greater exposures than product use. Product disposal has potential to present significant individual risks, but uncertainties concerning current and future routes of product disposal make it difficult to be definitive. Overall, additional exposure and dose-response data are needed to evaluate both the health significance of many exposure scenarios, and the adequacy of existing regulations to protect workers and the public. Although public exposures to beryllium and public awareness and concern regarding beryllium risks are currently low, beryllium risks have psychometric qualities that may lead to rapidly heightened public concern. 相似文献
8.
Casey Crump Kenny Crump Eric Hack Rose Luippold Kenneth Mundt Elizabeth Liebig Julie Panko Dennis Paustenbach Deborah Proctor 《Risk analysis》2003,23(6):1147-1163
This study evaluates the dose-response relationship for inhalation exposure to hexavalent chromium [Cr(VI)] and lung cancer mortality for workers of a chromate production facility, and provides estimates of the carcinogenic potency. The data were analyzed using relative risk and additive risk dose-response models implemented with both Poisson and Cox regression. Potential confounding by birth cohort and smoking prevalence were also assessed. Lifetime cumulative exposure and highest monthly exposure were the dose metrics evaluated. The estimated lifetime additional risk of lung cancer mortality associated with 45 years of occupational exposure to 1 microg/m3 Cr(VI) (occupational exposure unit risk) was 0.00205 (90%CI: 0.00134, 0.00291) for the relative risk model and 0.00216 (90%CI: 0.00143, 0.00302) for the additive risk model assuming a linear dose response for cumulative exposure with a five-year lag. Extrapolating these findings to a continuous (e.g., environmental) exposure scenario yielded an environmental unit risk of 0.00978 (90%CI: 0.00640, 0.0138) for the relative risk model [e.g., a cancer slope factor of 34 (mg/kg-day)-1] and 0.0125 (90%CI: 0.00833, 0.0175) for the additive risk model. The relative risk model is preferred because it is more consistent with the expected trend for lung cancer risk with age. Based on statistical tests for exposure-related trend, there was no statistically significant increased lung cancer risk below lifetime cumulative occupational exposures of 1.0 mg-yr/m3, and no excess risk for workers whose highest average monthly exposure did not exceed the current Permissible Exposure Limit (52 microg/m3). It is acknowledged that this study had limited power to detect increases at these low exposure levels. These cancer potency estimates are comparable to those developed by U.S. regulatory agencies and should be useful for assessing the potential cancer hazard associated with inhaled Cr(VI). 相似文献
9.
曾先峰 《长安大学学报(社会科学版)》2005,7(4):46-49
在对陕西4个地市进行调研的基础上,估算了该省民营经济的资金需求总量,并分析了其资金需求的结构。结果表明,民营经济的资金存在需求总量难以满足和供求结构失衡的矛盾,在目前国有金融体系支持有限的情况下,民营经济对民间资本产生了强烈的需求。因此解决民营经济融资困境的出路在于有效搭建民间资本投入到民营经济的桥梁和通道。 相似文献
10.
利用多能级Breit-Wigner公式对^60Ni的全截面进行了计算,并将计算结果与BNL-325(四版)进行比较。利用实验核数据库EXFOR提供的全截面数据及实验条件,对^60Ni的可分辩区实验全截面进行了评价,推荐出一套可用于校验共振参数的实验全截面数据并与计算结果进行了比较。 相似文献