全文获取类型
收费全文 | 1357篇 |
免费 | 179篇 |
国内免费 | 123篇 |
专业分类
安全科学 | 250篇 |
废物处理 | 13篇 |
环保管理 | 319篇 |
综合类 | 564篇 |
基础理论 | 172篇 |
污染及防治 | 32篇 |
评价与监测 | 155篇 |
社会与环境 | 85篇 |
灾害及防治 | 69篇 |
出版年
2024年 | 3篇 |
2023年 | 29篇 |
2022年 | 54篇 |
2021年 | 77篇 |
2020年 | 56篇 |
2019年 | 62篇 |
2018年 | 45篇 |
2017年 | 75篇 |
2016年 | 99篇 |
2015年 | 55篇 |
2014年 | 64篇 |
2013年 | 87篇 |
2012年 | 87篇 |
2011年 | 97篇 |
2010年 | 64篇 |
2009年 | 82篇 |
2008年 | 49篇 |
2007年 | 98篇 |
2006年 | 69篇 |
2005年 | 48篇 |
2004年 | 41篇 |
2003年 | 45篇 |
2002年 | 40篇 |
2001年 | 27篇 |
2000年 | 34篇 |
1999年 | 17篇 |
1998年 | 18篇 |
1997年 | 23篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 12篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1983年 | 2篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 6篇 |
1971年 | 3篇 |
1970年 | 1篇 |
排序方式: 共有1659条查询结果,搜索用时 15 毫秒
971.
桥梁结构健康监测的数据融合框架 总被引:1,自引:0,他引:1
大型桥梁结构健康监测系统需要安装大量各种类型的传感器,如何有效利用这些实时采集的信息以保障桥梁的连续安全运营是一个核心课题,而数据融合技术是解决这一问题的一个新方向。本文对近几十年来数据融合技术的发展做了全面综述,介绍了常用的数据融合模型,评析了各种常用融合算法。基于对健康监测系统的细致分析,在前人工作基础上,提出了桥梁结构健康监测的数据融合框架,对框架内的各个功能模块进行了功能定位,并给出了相应阶段适宜的融合算法。 相似文献
972.
Papadopoulos A Malamis S Moustakas K Kiranoudis CT Loizidou M 《Environmental monitoring and assessment》2007,130(1-3):255-270
This work focuses on the development and application of appropriate software tools for recording, assessing and reporting
data related to the operation of the Urban Wastewater Treatment Plants (UWTPs) in Cyprus. An appropriate Internet-Based Management
System was designed, developed and installed at the premises of the UWTPs and of the Cypriot Competent Authority (Water Development
Department — WDD) in order to coordinate and disseminate tasks and related information for monitoring the operation of UWTPs.
In addition, a client Geographical Information System database was compiled to be used for obtaining and analyzing spatial
information. The software tools are based on common procedures and state-of-the-art technology for the recording and transmission
of data and information and they provide an integrated view related to the operation and the efficiency of wastewater treatment
systems. Moreover, continuous control and systematic monitoring of the UWTPs by the operators as well as continuous and direct
supervision of the UWTPs environmental performance is achieved by the personnel of the Competent Authority. Furthermore, direct
and unobstructed provision of data to the Competent Authority of Cyprus is accomplished by the operators of the UWTPs, while
the Competent Authority is supported to compose full and representative reports to the European Commission and other International
Organizations. The developed tools enable the direct recording of data obtained through measurements and analyses, permit
the comparison of data with existing legislation and provide an integrated picture of the operation of the wastewater treatment
plants as well as the option to focus and assess each individual treatment stage. 相似文献
973.
Addressing landscape-level threats to stream fishes such as habitat and hydrological alterations requires adequate watershed-level
species inventories. Where watershed-level ichthyofaunal surveys are prohibitively expensive, existing (historical) data sources
may provide an option for compiling species lists. However, it is critical that managers consider potential biases or limitations
of species lists compiled from existing data. Here we assess the suitability of species lists compiled from existing data
sources for making watershed-level fish management and conservation decisions. For nine Great Lakes watersheds, we developed
existing species lists by compiling all available federal and state agency and museum fish survey data. We then compared the
size and species composition of existing species lists to current species lists compiled from intensive field surveys, conducted
in 2002, of the same watersheds. Species lists compiled from commonly available existing data sources, such as state and federal
agency and museum data, missed many species detected during our 2002 field surveys. In most watersheds, more than 10 species
were missed (range 5–21) on existing lists. Sampling over multiple years and seasons increased the size of both current (field)
and existing species lists. Existing species lists compiled from surveys conducted over multiple years and seasons included
an average of 15 species not captured during the 2002 field surveys. However, such multiyear existing datasets are rare and
not available for many watersheds. In addition, species lists compiled from older existing surveys (e.g., before 1984) did
not accurately represent current species composition of the watersheds and our results indicate several apparent misidentifications
or errors on these lists. Lastly, while most game species were detected on existing lists, migratory species and recently
introduced species were commonly missed on these lists. We conclude with recommendations for using existing data for watershed-level
stream fish management and conservation decisions. 相似文献
974.
975.
Lieven Declerck Geert Molenberghs Marc Aerts Louise Ryan 《Environmental and Ecological Statistics》2000,7(1):57-76
Developmental toxicity experiments are designed to assess potential adverse effects of drugs and other exposures on developing fetuses from pregnant dams. Extrapolation to humans is a very difficult problem. An important issue here is whether risk assessment should be based on the fetus or the litter level. In this paper, fetus and litter-based risks that properly account for cluster size are defined and compared for the beta-binomial model and a conditional model for clustered binary data. It is shown how the hierarchical structure of non-viable implants and viable but malformed offspring can be incorporated. Risks based on a joint model for death/resorption and malformation are contrasted with risks based on an adverse event defined as either death/resorption or malformation. The estimation of safe exposure levels for all risk types is discussed and it is shown how estimation of the cluster size distribution affects variance estimation. The methods are applied to data collected under the National Toxicology Program and in large sample simulations. 相似文献
976.
Preisler Haiganoush K. Haase Sally M. Sackett Stephen S. 《Environmental and Ecological Statistics》2000,7(3):239-254
Prescribed fire is a management tool used by wildland resource management organizations in many ecosystems to reduce hazardous fuels and to achieve a host of other objectives. To study the effects of fire in naturally accumulating fuel conditions, the ambient soil temperature is monitored beneath prescribed burns. In this study we developed a stochastic model for temperature profiles (values at 15 minute intervals) recorded at four depths beneath the soil during a large prescribed burn study. The model was used to assess the temporal fit of the data to particular solutions of the heat equation. We used a random effects model to assess the effects of observed site characteristics on maximum temperatures and to estimate risks of temperatures exceeding critical levels in future similar prescribed fires. Contour plots of estimated risks of temperatures exceeding 60°C for a range of fuel levels and soil depths indicated high risks of occurrence, especially when the moisture levels are low. However, the natural variability among sites seems to be large, even after controlling fuel and moisture levels, resulting in large standard errors of predicted risks. 相似文献
977.
浅议环境监测数据的审核 总被引:1,自引:0,他引:1
叶萍 《中国环境管理干部学院学报》2010,20(2):54-56
环境监测数据的审核工作是整个质量保证体系中最后有效的质量控制手段。针对我国环境监测数据审核现状与存在的问题,将"五性"质量指标贯穿于整个环境监测工作当中,是提升监测数据的审核力度,保证监测数据正确、可靠的有力措施之一。 相似文献
978.
地表水自动监测网数据自动审核的创新与实践 总被引:1,自引:0,他引:1
在地表水质量自动监测网络的质量保证管理中,山东省省、市两级监控中心使用计算机数据审核系统对监测数据进行实时监控和质量控制,创新地实现了对监测数据有效性的自动判别、监测网的运行情况自动评价等自动化质控措施。 相似文献
979.
Areal FJ Touza J MacLeod A Dehnen-Schmutz K Perrings C Palmieri MG Spence NJ 《Journal of environmental management》2008,89(4):300-307
This paper analyses the cut flower market as an example of an invasion pathway along which species of non-indigenous plant pests can travel to reach new areas. The paper examines the probability of pest detection by assessing information on pest detection and detection effort associated with the import of cut flowers. We test the link between the probability of plant pest arrivals, as a precursor to potential invasion, and volume of traded flowers using count data regression models. The analysis is applied to the UK import of specific genera of cut flowers from Kenya between 1996 and 2004.There is a link between pest detection and the Genus of cut flower imported. Hence, pest detection efforts should focus on identifying and targeting those imported plants with a high risk of carrying pest species. For most of the plants studied, efforts allocated to inspection have a significant influence on the probability of pest detection. However, by better targeting inspection efforts, it is shown that plant inspection effort could be reduced without increasing the risk of pest entry. Similarly, for most of the plants analysed, an increase in volume traded will not necessarily lead to an increase in the number of pests entering the UK. For some species, such as Carthamus and Veronica, the volume of flowers traded has a significant and positive impact on the likelihood of pest detection. We conclude that analysis at the rank of plant Genus is important both to understand the effectiveness of plant pest detection efforts and consequently to manage the risk of introduction of non-indigenous species. 相似文献
980.
Activated carbons derived from oil palm empty-fruit bunches: Application to environmental problems 总被引:1,自引:1,他引:0
Md. Zahangir ALAM Suleyman A. MUYIBI Mariatul F. MANSOR Radziah WAHID 《环境科学学报(英文版)》2007,19(1):103-108
Activated carbons derived from oil palm empty fruit bunches (EFB) were investigated to find the suitability of its application for removal of phenol in aqueous solution through adsorption process, Two types of activation namely; thermal activation at 300, 500 and 800℃and physical activation at 150℃ (boiling treatment) were used for the production of the activated carbons. A control (untreated EFB) was used to compare the adsorption capacity of the activated carbons produced from these processes. The results indicated that the activated carbon derived at the temperature of 800℃ showed maximum absorption capacity in the aqueous solution of phenol. Batch adsorption studies showed an equilibrium time of 6 h for the activated carbon at 800℃. It was observed that the adsorption capacity was higher at lower values of pH (2-3) and higher value of initial concentration of phenol (200-300 mg/L). The equilibrium data fitted better with the Freundlich adsorption isotherm compared to the Langmuir. Kinetic studies of phenol adsorption onto activated carbons were also studied to evaluate the adsorption rate. The estimated cost for production of activated carbon from EFB was shown in lower price (USD 0.50/kg of activated carbon) compared the activated carbon from other sources and processes. 相似文献