全文获取类型
收费全文 | 437篇 |
免费 | 16篇 |
国内免费 | 4篇 |
专业分类
管理学 | 100篇 |
民族学 | 2篇 |
人口学 | 1篇 |
丛书文集 | 19篇 |
理论方法论 | 3篇 |
综合类 | 267篇 |
社会学 | 18篇 |
统计学 | 47篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 3篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 22篇 |
2014年 | 23篇 |
2013年 | 36篇 |
2012年 | 23篇 |
2011年 | 23篇 |
2010年 | 23篇 |
2009年 | 17篇 |
2008年 | 15篇 |
2007年 | 27篇 |
2006年 | 17篇 |
2005年 | 16篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 13篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 19篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有457条查询结果,搜索用时 15 毫秒
61.
刘永富 《西安交通大学学报(社会科学版)》2004,24(4):72-75
根据已知的文献资料,可以把阿那克西米尼的哲学看作以气为最高根据去说明一切的气一元论哲学。气、气的性质、气的形态三者的有机统一构成了一切事物的基本模型。阿那克西米尼的哲学在有记载的西方哲学史上首次揭示了量的原则在事物形成中的作用,但也因此产生了某些逻辑上的困难。 相似文献
62.
从室内空气污染物主要来源、污染物及其危害入手,针对我国国情和以往我国室内空气质量控制存在的问题,从社会、技术等角度提出行政管理对策和技术防治对策. 相似文献
63.
湛江大气环境质量现状与分析研究 总被引:4,自引:0,他引:4
湛江2000~2002年的空气质量年总优良率的横(纵)向对比结果显示:3年来,湛江大气环境质量总体达到国家空气质量Ⅰ级标准(优)、Ⅱ级标准(良)分别占59.91%、40.09%;年度Ⅰ级(优)总天数比率分别为86.65%、70.14%、23.08%,其中2001年的空气质量Ⅰ级(优)率比2000年下降16.51个百分点,2002年的空气质量Ⅰ级(优)率比2001年下降47.06个百分点,比2000年下降63.57个百分点,空气质量变化较大,呈直线下降趋势.月均污染指数、季均优良率的横向和纵向对比结果也表明,近年湛江空气质量逐渐下降,应引起注意. 相似文献
64.
An approach, using biomarkers (biological responses) for assessing the biological and ecological significance of contaminants present in the environment is described. Living organisms integrate exposure to contaminants in their environment and respond in some measurable and predictable way. Responses are observed at several levels of biological organization from the biomolecular level, where pollutants can cause damage to critical cellular macromolecules and elicit defensive strategies such as detoxication and repair mechanisms, to the organismal level, where severe disturbances are manifested as impairment in growth, reproduction, developmental abnormalities, or decreased survival. Biomarkers can provide not only evidence of exposure to a broad spectrum of anthropogenic chemicals, but also a temporally integrated measure of bioavailable contaminant levels. A suite of biomarkers are evaluated over time to determine the magnitude of the problem and possible consequences. Relationships between biomarker response and adverse ecological effects are determined from estimates of animal health and population structure. 相似文献
65.
M. Granger Morgan Samuel C. Morris Max Henrion Deborah A. L. Amaral William R. Rish 《Risk analysis》1984,4(3):201-216
Expert judgments expressed as subjective probability distributions provide an appropriate means of incorporating technical uncertainty in some quantitative policy studies. Judgments and distributions obtained from several experts allow one to explore the extent to which the conclusions reached in such a study depend on which expert one talks to. For the case of sulfur air pollution from coal-fired power plants, estimates of sulfur mass balance as a function of plume flight time are shown to vary little across the range of opinions of leading atmospheric scientists while estimates of possible health impacts are shown to vary widely across the range of opinions of leading scientists in air pollution health effects. 相似文献
66.
Clint W. Coakley Thomas P. Hettmansperger 《Australian & New Zealand Journal of Statistics》1994,36(2):225-233
The breakdown point of an estimator is the smallest fraction of contamination that can force the value of the estimator beyond the boundary of the parameter space. It is well known that the highest possible breakdown point, under equivariance restrictions, is 50% of the sample. However, this upper bound is not always attainable. We give an example of an estimation problem in which the highest possible attainable breakdown point is much less than 50% of the sample. For hypothesis testing, we discuss the resistance of a test and propose new definitions of resistance. The maximum resistance to rejection (acceptance) is the smallest fraction of contamination necessary to force a test to reject (fail to reject) regardless of the original sample. We derive the maximum resistances of the t-test and sign test in the one-sample problem and of the t-test and Mood test in the two-sample problem. We briefly discuss another measure known as the expected resistance. 相似文献
67.
刘蔡月 《内蒙古工业大学学报》1995,(4)
本文提出了湿空气的图解法,导出了符合工程习惯的湿空气的计算式,绘制了湿空气的-温图,-压图与-湿图,并给出了算例。本文所提供的湿空气的图解法使湿空气的计算与湿空气其它参数的计算一样简便。 相似文献
68.
We consider the scheduling of truck arrivals at an air cargo terminal. By coordinating arrivals of cargo delivery trucks with outbound flight departure schedules, some of the shipments can be transferred directly to the departing flights, while others will be stored at the terminal's storage facility and incur extra handling and storage costs. The objective is to obtain a feasible schedule so as to minimize the total cost of operations. We formulate the problem as a time‐indexed integer program and show that, even with limited number of unloading docks at the terminal, the problem is non‐trivial (NP‐hard in the strong sense). Our solution method includes an exact solution procedure to determine an optimal unloading sequence for the shipments carried by each truck, together with a Lagrangian relaxation‐based heuristic for assigning trucks to truck docks and determining truck arrival times. We conducted computational experiments to test the performance of our solution method. Computational results show that our method can generate near‐optimal solutions efficiently. Our simulation results indicate that the scheduling approach proposed in this paper has the potential to generate significant cost savings over a first‐come, first‐served approach currently used at the air cargo terminal that we observed. 相似文献
69.
利用AVL公司开发的FIRE软件,对一典型结构蒸发混合式汽车加热器燃烧室内的燃烧过程进行了数值模拟.其中,蒸发和燃烧分别采用Wall Film模型、Coherent Flame模型,氮氧化物(NOx)采用Zeldovich不平衡原理建模,碳烟(Soot)模型为FIRE模型.计算结果及分析表明,一层进气孔布置对燃油蒸汽浓度分布影响很大.加大进气孔直径使进气中心涡流增强,燃油在一级燃烧室中蒸发量增加.主要燃烧发生在二级燃烧室.进气孔切向进气能形成较强的中心涡流,使燃烧高温区主要集中在二级燃烧室的纵向轴心附近.一级燃烧室的周向涡区和二级燃烧室上半部的高温区是Soot生成速率最大的部位;最高燃烧温度未达NOx的生成温度条件,其生成量极少. 相似文献
70.
白靖 《燕山大学学报(哲学社会科学版)》2006,7(2):21-25
"阴阳"物质观念的形成经历了原始阴阳观念、气分阴阳观念和科学阴阳观念三个历史阶段,中国古代贤哲制造了土圭、阳燧等工具并进行了长期的高山探索,证明了阴阳现象的物质基础. 相似文献