全文获取类型
收费全文 | 387篇 |
免费 | 29篇 |
国内免费 | 19篇 |
专业分类
安全科学 | 45篇 |
废物处理 | 5篇 |
环保管理 | 186篇 |
综合类 | 81篇 |
基础理论 | 43篇 |
污染及防治 | 3篇 |
评价与监测 | 29篇 |
社会与环境 | 27篇 |
灾害及防治 | 16篇 |
出版年
2023年 | 4篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2017年 | 11篇 |
2016年 | 16篇 |
2015年 | 11篇 |
2014年 | 11篇 |
2013年 | 17篇 |
2012年 | 5篇 |
2011年 | 23篇 |
2010年 | 13篇 |
2009年 | 17篇 |
2008年 | 23篇 |
2007年 | 26篇 |
2006年 | 15篇 |
2005年 | 20篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 18篇 |
2001年 | 12篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 7篇 |
1971年 | 9篇 |
1970年 | 3篇 |
排序方式: 共有435条查询结果,搜索用时 15 毫秒
11.
平原河网地区非点源污染风险差异化分区防控研究 总被引:1,自引:0,他引:1
土地利用优化和空间防控策略对非点源污染风险控制及水环境质量的改善具有重要意义。本文以太湖流域典型平原河网地区-上海市青浦区为研究对象,将灰色线性规划模型与最小累积阻力模型相结合,以控制非点源污染风险和增加经济效益、生态效益为目标,进行土地利用结构优化与空间分区防控研究,在空间上划设了水资源保育区、水资源重点防护区、非点源污染一般阻控区、非点源污染中等阻控区及非点源污染重点阻控区,并针对不同分区提出具有针对性的防控措施。与2012年相比,预测2020年优化防控方案下,可减少总氮、总磷的输出10.96%和41.33%。由此表明,优化土地利用结构和构建空间差异化防控机制是有效调控非点源污染风险,实现区域可持续土地利用,促进经济发展和保证生态环境安全的有效途径。 相似文献
12.
王新泉 《中国安全科学学报》2007,17(5):42-46
以郑州市安全生产"十一五"发展规划的编制为例,以实证研究的方法,就地方政府编制安全生产"十一五"发展规划的总体思路、基本编制原则、主要任务、安全发展目标和指标体系的科学性、可行性、合理性,支撑工程的规划与建设、保障措施的制定等进行研究,着重论述在编制地方安全生产"十一五"发展规划时应着力把握的综合协调,有序衔接,突出重点,与时俱进及表达形式等问题,指出具体编制工作中的着力点是确定发展方向和目标,做实做深本地安全生产现状的调研和安全生产形势预测分析,加强对重大问题的研究。给出了编制地方安全生产"十一五"发展规划具体方法和步骤与程序。 相似文献
13.
研究表明:CALPUFF模式是运用于广域的大气扩散模型,在区域范围较大的复杂地形条件下的应用具有突出的优势.利用CALPUFF大气扩散模型模拟漳州市2009年气象场和污染物浓度场,采用监测值对模拟结果进行验证表明模型的适用性;基于现状污染源,建立大气污染物传递系数矩阵,结合线性优化法测算了不同环境空气质量标准下漳州市大气环境容量. 相似文献
14.
Irrigation Water Allocation Using an Inexact Two‐Stage Quadratic Programming with Fuzzy Input under Climate Change
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mo Li Ping Guo Vijay P. Singh Jie Zhao 《Journal of the American Water Resources Association》2016,52(3):667-684
Agricultural irrigation accounts for nearly 70% of the total water use around the world. Uncertainties and climate change together exacerbate the complexity of optimal allocation of water resources for irrigation. An interval‐fuzzy two‐stage stochastic quadratic programming model is developed for determining the plans for water allocation for irrigation with maximum benefits. The model is shown to be applicable when inputs are expressed as discrete, fuzzy or random. In order to reflect the effect of marginal utility on benefit and cost, the model can also deal with nonlinearities in the objective function. Results from applying the model to a case study in the middle reaches of the Heihe River basin, China, show schemes for water allocation for irrigation of different crops in every month of the crop growth period under various flow levels are effective for achieving high economic benefits. Different climate change scenarios are used to analyze the impact of changing water requirement and water availability on irrigation water allocation. The proposed model can aid the decision maker in formulating desired irrigation water management policies in the wake of uncertainties and changing environment. 相似文献
15.
研究以各区域灾害风险评估系数作为权重系数,对山地小城市各区域避难场所进行优化布局。首先,通过风险值=危险性*脆弱性/抗灾救灾能力机理表达式构建灾害风险评估指标体系,并以模糊综合评价法得出灾害风险评估数值,在此基础上通过多目标选址优化模型来构建山地城市避难场所的优化模型,其中灾害风险评估系数作为影响布局的权重因素纳入其中。最后,以东川区为研究对象,对其固定避难场所进行优化布局研究,结果表明:东川区城区固定避灾场所数量可在接近最优解的情况下达到效果最优。 相似文献
16.
Bart Van der Straeten Jeroen Buysse Stephan Nolte Ludwig Lauwers Dakerlia Claeys Guido Van Huylenbroeck 《Journal of Environmental Planning and Management》2010,53(8):1011-1030
The EU Nitrate Directive has spurred many countries to regulate manure production and manure application. Farmers have three allocation options: spreading manure on their own land, transporting manure to other farmers' land or processing manure. The manure problem can be seen as an allocation problem. To better understand this allocation problem, we have developed the spatial mathematical programming multi-agent simulation (MP-MAS) model. This model has been applied in Flanders, Belgium, a region with a high concentration of livestock. The model evaluates the cost efficiency of policy intervention in the manure market through obliged processing. We propose to further optimise the policy using a regionally differentiated manure pressure indicator, which is directly derived from the dual outcome of the mathematical programme. This indicator increases transparency in the manure and processing market, leading to better decision support about location and type of manure processing. 相似文献
17.
An Interval-Parameter Waste-Load-Allocation Model for River Water Quality Management Under Uncertainty 总被引:1,自引:0,他引:1
A simulation-based interval quadratic waste load allocation (IQWLA) model was developed for supporting river water quality
management. A multi-segment simulation model was developed to generate water-quality transformation matrices and vectors under
steady-state river flow conditions. The established matrices and vectors were then used to establish the water-quality constraints
that were included in a water quality management model. Uncertainties associated with water quality parameters, cost functions,
and environmental guidelines were described as intervals. The cost functions of wastewater treatment units were expressed
in quadratic forms. A water-quality planning problem in the Changsha section of Xiangjiang River in China was used as a study
case to demonstrate applicability of the proposed method. The study results demonstrated that IQWLA model could effectively
communicate the interval-format uncertainties into optimization process, and generate inexact solutions that contain a spectrum
of potential wastewater treatment options. Decision alternatives can be generated by adjusting different combinations of the
decision variables within their solution intervals. The results are valuable for supporting local decision makers in generating
cost-effective water quality management strategies. 相似文献
18.
结构分析中模拟与仿真技术研究 总被引:5,自引:1,他引:4
由于像洪水、水灾、地震这样一类自然灾害的原型重复试验几乎是不可能的,因此计算机仿真技术在这一领域的应用具有重要的意义。本文探索了土木工程中模拟与仿真的概念、特征及实现途径,阐述了关于仿真智能化、可视化的技术细节及仿真的基本思路;结合面向对象程序设计(OOP)概念,提出了结构分析程序设计的原则及标准。在此基础上,编写了基于Windows的结构有限元分析软件SmartSEA. 相似文献
19.
A mixed-integer programming model that minimizes the social abatement cost is used to investigate whether a market equilibrium
condition could be reached in a newly proposed permit-trading market for nitrogen oxide control in Taiwan. Unlike in previous
studies, unit pollution abatement cost is determined endogenously by incorporating technology adoption as a binary decision
variable. The results show that when technologies are lumpy and irreversible, disequilibrium might occur due to firms’ inability
to manage their emission levels after installing equipment with fixed size and control capacity.
相似文献
Chao-ning LiaoEmail: |
20.
Mixed-integer linear programs are proposed for siting development and conservation areas in watersheds, addressing economic
objectives (development perimeter and proximity) and ecological objectives. Links between watershed hydrology and ecology
need not be well defined. Parameters for the linear programs are obtained from linearization of the SWAT hydrologic model. 相似文献