全文获取类型
收费全文 | 14187篇 |
免费 | 706篇 |
国内免费 | 182篇 |
专业分类
管理学 | 1281篇 |
劳动科学 | 2篇 |
民族学 | 245篇 |
人才学 | 1篇 |
人口学 | 261篇 |
丛书文集 | 1132篇 |
理论方法论 | 779篇 |
综合类 | 8931篇 |
社会学 | 1445篇 |
统计学 | 998篇 |
出版年
2024年 | 79篇 |
2023年 | 189篇 |
2022年 | 246篇 |
2021年 | 280篇 |
2020年 | 386篇 |
2019年 | 328篇 |
2018年 | 357篇 |
2017年 | 448篇 |
2016年 | 430篇 |
2015年 | 520篇 |
2014年 | 797篇 |
2013年 | 1507篇 |
2012年 | 985篇 |
2011年 | 972篇 |
2010年 | 712篇 |
2009年 | 618篇 |
2008年 | 765篇 |
2007年 | 902篇 |
2006年 | 878篇 |
2005年 | 777篇 |
2004年 | 669篇 |
2003年 | 608篇 |
2002年 | 442篇 |
2001年 | 367篇 |
2000年 | 261篇 |
1999年 | 125篇 |
1998年 | 67篇 |
1997年 | 58篇 |
1996年 | 59篇 |
1995年 | 52篇 |
1994年 | 43篇 |
1993年 | 24篇 |
1992年 | 22篇 |
1991年 | 19篇 |
1990年 | 18篇 |
1989年 | 14篇 |
1988年 | 14篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
Recently, we developed a GIS-Integrated Integral Risk Index (IRI) to assess human health risks in areas with presence of environmental pollutants. Contaminants were previously ranked by applying a self-organizing map (SOM) to their characteristics of persistence, bioaccumulation, and toxicity in order to obtain the Hazard Index (HI). In the present study, the original IRI was substantially improved by allowing the entrance of probabilistic data. A neuroprobabilistic HI was developed by combining SOM and Monte Carlo analysis. In general terms, the deterministic and probabilistic HIs followed a similar pattern: polychlorinated biphenyls (PCBs) and light polycyclic aromatic hydrocarbons (PAHs) were the pollutants showing the highest and lowest values of HI, respectively. However, the bioaccumulation value of heavy metals notably increased after considering a probability density function to explain the bioaccumulation factor. To check its applicability, a case study was investigated. The probabilistic integral risk was calculated in the chemical/petrochemical industrial area of Tarragona (Catalonia, Spain), where an environmental program has been carried out since 2002. The risk change between 2002 and 2005 was evaluated on the basis of probabilistic data of the levels of various pollutants in soils. The results indicated that the risk of the chemicals under study did not follow a homogeneous tendency. However, the current levels of pollution do not mean a relevant source of health risks for the local population. Moreover, the neuroprobabilistic HI seems to be an adequate tool to be taken into account in risk assessment processes. 相似文献
122.
Joanna Burger Michael Gochfeld Karen Pletnikoff Ronald Snigaroff Daniel Snigaroff Tim Stamm 《Risk analysis》2008,28(5):1261-1272
It is becoming increasingly clear that scientists, managers, lawyers, public policymakers, and the public must decide how to value what is provided by, and is a consequence of, natural resources. While “Western” scientists have clear definitions for the goods and services that ecosystems provide, we contend that these categories do not encompass the full totality of the values provided by natural resources. Partly the confusion results from a limited view of natural resources derived from the need to monetize the value of ecosystems and their component parts. Partly it derives from the “Western” way of separating natural resources from cultural resources or values, and partly it derives from the false dichotomy of assuming that ecosystems are natural, and anything constructed by man is not natural. In this article, we explore the previous assumptions, and suggest that because cultural resources often derive from, and indeed require, intact and unspoiled natural ecosystems or settings, that these values are rightly part of natural resources. The distinction is not trivial because of the current emphasis on cleaning up chemically and radiologically contaminated sites, on restoration of damaged ecosystems, on natural resource damage assessments, and on long‐term stewardship goals. All of these processes depend upon defining natural resources appropriately. Several laws, regulations, and protocols depend upon natural resource trustees to protect natural resources on trust lands, which could lead to the circular definition that natural resources are those resources that the trustees feel they are responsible for. Where subsistence or tribal peoples are involved, the definition of natural resources should be broadened to include those ecocultural attributes that are dependent upon, and have incorporated, natural resources. For example, a traditional hunting and fishing ground is less valued by subsistence peoples if it is despoiled by contamination or physical ecosystem degradation; an Indian sacred ground is tarnished if the surrounding natural environment is degraded; a traditional homeland is less valued if the land itself is contaminated. Our argument is that intact natural resources are essential elements of many cultural resources, and this aspect requires and demands adequate consideration (and may therefore require compensation). 相似文献
123.
基于旅西日本游客旅游选择行为的西安旅游市场分析 总被引:1,自引:0,他引:1
根据在全国六大旅游热点城市所做的旅游市场调查的数据结果,对旅西日本游客的旅游选择行为进行了研究,同时进一步有针对性地对西安日本客源市场进行了SWOT分析,在此基础上,对西安旅游业的发展提出了相关对策建议。 相似文献
124.
何小春 《辽宁工程技术大学学报(社会科学版)》2007,9(6):567-569
探讨了儒、道"天人合一"观在生态伦理问题上态度之异同:基于天地生人、万物一体这一共同的根本观念,在人合自然的实践路径上,道家以自然为基点,讲求遵道而行、顺应自然;儒家则主张发挥人的作用力改造自然、人化自然。儒、道还从伦理规范层面提出了人与自然和谐发展的道德要求,为当代社会解决生态危机提供了借鉴。 相似文献
125.
This study reports on New Zealand dairy farmers’ access to and use of information as mediated through conditions of risk and trust within the context of their interpersonal social networks. We located participants’ reports of their information use within their perceived environments of trust and risk, following Giddens's [1990. The consequences of modernity. Polity Press, Stanford, CA] typology of trust and risk in pre-modernity and modernity. The research participants were constant users of interpersonal and print information from numerous sources, and monitored their incoming data in the light of strategic needs, reflecting their roles as both farming practitioners and business owners. Socio-spatial knowledge networks (SSKNs) combine individuals’ explanatory cognitive models of information acquisition and use with a micro-geographical analysis of their interpersonal networks. The participants showed characteristics of pre-modern, modern and even post-modern society in respect of their use of complex interactional forms, as well as a blending of individualistic and communitarian practices and concerns in their professional and personal lives. 相似文献
126.
给出了四元数体Q上n×n分块矩阵为亚(半)正定自共轭矩阵的一个充要条件,进而给出了Q上矩阵方程XAnm=Bnm有亚(半)正定自共轭四元数矩阵解的充要条件及解集合的显式表示,从而推广改进了数城上线性方程组的反问题及矩阵反问题的相应结果. 相似文献
127.
以传统政府模式转型成“企业化政府”模式为典型,把已经在企业内部取得瞩目成就的平衡计分卡管理模式引入“企业化政府”管理模式,增强政府改革的可行性和有效性。 相似文献
128.
池丽萍 《中华女子学院学报》2005,17(6):82-85
研究表明:幼儿家长在教养活动中同时运用支持、惩戒和溺爱三种教养行为,但三种行为在其全部教养行为中所占比例不同,支持行为最多,惩戒和溺爱行为较少;家长的支持教养行为与其对子女的控制感呈正相关,而惩戒和溺爱行为则与控制感呈负相关. 相似文献
129.
许琪琳 《中国农业大学学报(社会科学版)》2005,22(3):39-42+59
中小企业在其不同的发展阶段面临着不同的融资需求。文章以金融支持为主线,先从宏观层面上考察了企业融资结构分别对宏观经济波动和企业融资体系的影响,再从微观角度出发,试图在对中小企业各发展过程中融资行为、融资约束、融资结构等的分析中探求其“融资难”之所在。最后再依据我国的现实国情,并结合发达国家先进经验,探讨我国中小企业融资体系的构建。 相似文献
130.
本文研究描述传染病现象的一类Kermack—Mekandrick方程组初值问题光滑解整体存在唯一性及渐近性质。 相似文献