全文获取类型
收费全文 | 13799篇 |
免费 | 1058篇 |
国内免费 | 1240篇 |
专业分类
安全科学 | 1873篇 |
废物处理 | 198篇 |
环保管理 | 4505篇 |
综合类 | 5206篇 |
基础理论 | 1401篇 |
环境理论 | 10篇 |
污染及防治 | 523篇 |
评价与监测 | 1495篇 |
社会与环境 | 569篇 |
灾害及防治 | 317篇 |
出版年
2024年 | 32篇 |
2023年 | 194篇 |
2022年 | 249篇 |
2021年 | 343篇 |
2020年 | 417篇 |
2019年 | 329篇 |
2018年 | 285篇 |
2017年 | 422篇 |
2016年 | 540篇 |
2015年 | 511篇 |
2014年 | 624篇 |
2013年 | 829篇 |
2012年 | 843篇 |
2011年 | 1007篇 |
2010年 | 692篇 |
2009年 | 807篇 |
2008年 | 622篇 |
2007年 | 861篇 |
2006年 | 836篇 |
2005年 | 635篇 |
2004年 | 627篇 |
2003年 | 545篇 |
2002年 | 503篇 |
2001年 | 448篇 |
2000年 | 447篇 |
1999年 | 350篇 |
1998年 | 241篇 |
1997年 | 243篇 |
1996年 | 215篇 |
1995年 | 185篇 |
1994年 | 128篇 |
1993年 | 116篇 |
1992年 | 98篇 |
1991年 | 96篇 |
1990年 | 52篇 |
1989年 | 56篇 |
1988年 | 66篇 |
1987年 | 56篇 |
1986年 | 46篇 |
1985年 | 39篇 |
1984年 | 47篇 |
1983年 | 37篇 |
1982年 | 44篇 |
1981年 | 41篇 |
1980年 | 49篇 |
1979年 | 56篇 |
1978年 | 33篇 |
1977年 | 25篇 |
1973年 | 26篇 |
1972年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
详细介绍了“城市空气质量日报自动发布系统”的开发背景和开发过程 ,并对系统整体的架构和所用到的技术作了针对性的说明 ,阐明了作者对此类系统的前景和发展方向的看法。 相似文献
93.
94.
质量保证体系是网格实测法环境空气质量监测优化布点研究工作的重要组成 ,该体系可确保实测数据准确可靠和研究成果质量 ,具有可操作性并已在实践中应用 ,取得满意效果 相似文献
95.
96.
基于B-P神经网络的环境质量评价方法 总被引:3,自引:0,他引:3
提出可将环境质量评价的无论是定量指标还是定性参数转化成"二进制"的"1"或"0",进而将这种二进制数引入B-P网络.通过实例探讨,这种新的B-P网络既适用于定量指标的水质参数又适用于定性指标的水质参数. 相似文献
97.
区域生态系统适应性管理概念、理论框架及其应用研究 总被引:8,自引:0,他引:8
论述了生态系统适应性管理基本概念与生态系统适应循环,着重分析了生态系统恢复力范围、抗性、不稳定性与跨尺度影响。生态系统适应循环通常经历入侵、保持、破坏、调整四个阶段,前两个阶段的生态系统演替是可以预测的,而后两个阶段是复杂、难以预测的。文章提出了适应性区域生态系统管理的基本概念,并构建了其理论框架,并以三峡库区小江流域为例,对小江流域景观生态特征、区域生态胁迫进行了详细分析。在此基础上,提出要以水生生态安全为总目标,并围绕这一目标,进行流域各生态系统的恢复力辨识、生态系统适应性循环过程研究,从各系统恢复力属性特征出发,提出了具体的适应性管理方法与模式。 相似文献
98.
Macroinvertebrate Regionalisation for use in the Management of Aquatic Ecosystems in Victoria, Australia 总被引:5,自引:0,他引:5
The development of a broader, more holistic approach to aquaticecosystem management has been called for in recent years. Physical and chemical objectives alone are no longer consideredsufficient for the protection of aquatic ecosystems and shouldbe supplemented with biological objectives. The ubiquitousand sedentary nature of macroinvertebrates, combined with theirmeasurable response to environmental conditions, favour their use as important indicators in environmental policies. To establish biological objectives, there is a need for a regionalframework to limit the variability between ecosystems. Past studies have demonstrated that an a posteriori regionalisationapproach may be more useful than an a priori approach in explaining single component (e.g. macroinvertebrates) patternsacross ecosystems. This is particularly important as aquaticresource management agencies often focus on one or twocomponents of the ecosystem to assess environmental health. This study uses an a posteriori method to delineate and describebiological regions based on edge and riffle macroinvertebrate data. The regionalisation will provide a framework for settingbiological objectives, based on the range of reference conditionsmeasured within each separate region. The objectives will includeregional checklists for taxa and biotic indices. Predictive modelling in the style of RIVPACS or AUSRIVAS will also be usedwithin each region to develop objectives, incorporating local, regional and systematic features as predictor variables. 相似文献
99.
Finnamore A Alonso A Santisteban J Cordova S Valencia G de la Cruz A Polo R 《Environmental monitoring and assessment》2002,76(1):43-53
By applying principles of adaptive management, and by using the valuable information that arthropods provide from assessment and monitoring programs, managers can identify and reduce possible impacts on biodiversity in development projects. In 1996, the Smithsonian Institution's Monitoring and Assessment of Biodiversity program worked together with Shell Prospecting and Development Peru to establish an adaptive management program to protect biodiversity in a natural gas exploration project in a Peruvian rainforest. In this paper, we outlined the conceptual steps involved in establishing an assessment and monitoring program for arthropods, including setting objectives, evaluating the results and making decisions. We also present the results of the assessment using some of groups of arthropods, and summarize the steps taken to identify appropriate groups for monitoring. 相似文献
100.
MARTIN A. STAPANIAN STEVEN P. CLINE DAVID L. CASSELL 《Environmental monitoring and assessment》1997,45(3):237-257
We evaluate a field method for determining species richness andcanopy cover of vascular plants for the Forest Health MonitoringProgram (FHM), an ecological survey of U.S. forests. Measurementsare taken within 12 1-m2 quadrats on 1/15 ha plots in FHM.Species richness and cover are determined for four height classes(strata) within each quadrat and aggregated by stratum over the entireplot. We estimated (1) the agreement between experienced trainers andinexperienced technicians who collected the data on this survey(accuracy) and (2) the agreement among the technicians (precision) forresults on species richness and cover from 3 test plots at 3 timeintervals. The methods appear to be highly precise, although somediscrepancies with the values obtained by the trainers were found.Trainers found significantly more species in the ground stratum (0–0.6 m) and measured significantly more cover in the uppermost stratum(>4.9 m). The proportion of variation due to measurement error andtemporal variability was less than 13% for species richness (all strata)and cover (all but one stratum). This indicates that the method issuitable for monitoring changes in species richness and canopy coverfor a large-scale synoptic monitoring project such as FHM. 相似文献