全文获取类型
收费全文 | 36篇 |
免费 | 4篇 |
国内免费 | 6篇 |
专业分类
安全科学 | 6篇 |
环保管理 | 5篇 |
综合类 | 18篇 |
基础理论 | 7篇 |
污染及防治 | 4篇 |
评价与监测 | 5篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 2篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有46条查询结果,搜索用时 31 毫秒
1.
滁州地区覆盖层厚度对场地地震动参数的影响 总被引:1,自引:0,他引:1
以滁州地区近百个钻孔资料为原型建立土层模型,采用一维频域等效线性化波动方法进行了土层地震反应分析,重点分析了覆盖层厚度对场地地震动参数的影响。研究结果表明,随着覆盖层厚度的增加,地表峰值加速度及土层放大系数逐渐增大,当覆盖层厚度超过一定值时,地表峰值加速度及土层放大系数呈逐渐缓慢减小的趋势;而反应谱特征周期总体上随着覆盖层厚度的增加而逐渐增大。 相似文献
2.
The paper presents the results of testing of roof runoff waters from buildings in the city of Gda
sk (Poland), carried out as a part of a broader research project aimed at the determination of pollutant levels in precipitation. The analytes determined included volatile organohalogen compounds, petroleum hydrocarbons, Na+, K+, NH4+, Mg2+, Ca2+, F−, Cl−, NO2−, NO3−, PO43−, SO42− ions, as well as organonitrogen, organophosphorus and organochlorine pesticides. In addition, the toxicity and pH of the samples were examined. The samples were collected over a period of six months, during or immediately following precipitation events. More than half of the samples (25) were found to be toxic, with inhibition exceeding 20%. The toxicity was weakly correlated to the levels of organonitrogen and organophosphorus pesticides in runoff waters. It was established that at least in some cases the roofing material affected the levels of the pollutants found in the samples. 相似文献
3.
薄膜覆盖减少化肥养分流失研究 总被引:7,自引:1,他引:6
我国化肥的利用率低,使用量又不断增长,增加了农业面源污染问题的严重性.本研究针对化肥流失主要通过水带走的特性,进行大田试验种植玉米,利用薄膜覆盖所施用的化肥,实现"肥与水隔离",以减少化肥流失.试验一方面观察了不同施肥处理二季甜玉米的生长和产量,另一方面测定了作物对肥料的利用率以及地表径流养分含量.结果表明,在本土壤条件下甜玉米只需施用常规施肥量的70%即可达到高产.甜玉米收获后土壤中碱解氮、有效磷、有效钾的含量比不经薄膜覆盖的显著提高,其顺序为100%施肥量+覆膜70%施肥量+覆膜100%施肥量、70%施肥量不施肥.氮、磷、钾肥料的表观利用率分别为42%~87%、0%~3%和5%~15%,覆膜处理一般高于不覆膜处理,特别是在高施肥量情况下更为明显.通过8次径流水的收集测定,无薄膜覆盖的施肥处理的地表径流N、P和K平均浓度分别为27.72、2.70和7.07 mg.L-1,薄膜覆盖技术处理降低N、P、K浓度的效果分别达到了39.54%、28.05%、43.74%,对于减少农业面源污染和水体富营养化可起到明显效果. 相似文献
4.
The efficiency of Taiwan's waste management and resource recycling systems has been well recognized in recent years, but the present model used to locate recycling centers and to assign collection depots to those centers continues to show low efficiency. To address this issue, the study herein suggests implementing a new location-planning and assignment model to reduce the number of existing recycling centers. Such a reduction would reduce the use of land resources. Moreover, the total transportation distance would decrease through the efficient assignment of collection depots to recycling centers. On the basis of results from previous studies, this study proposes a 2-stage location set covering problem-P-median integrated model that obtains exact solutions using heuristic algorithms on the basis of set operations. The results of numerical analyses show that the model introduced in this study is effective in solving the problems stated above as well as in improving the layout of Taiwan's existing recycling centers. 相似文献
5.
6.
采用模拟污染物的同位素示踪技术研究了客土覆盖对降低大豆中放射性铈积累的效应.结果表明,在受141Ce污染的土壤表面覆盖客土,能降低大豆对141Ce的吸收和积累,效果十分明显,当客土覆盖厚度为12cm时,豆根、豆秸、豆壳和豆籽中141Ce比活度分别下降了83.5%、30.6%、13.7%和11.8%;大豆中吸收积累的141Ce比活度随客土覆盖厚度的增加而下降,其中豆根中141Ce比活度与覆盖的客土厚度呈指数负相关,豆秸、豆壳、豆籽中141Ce比活度则与客土覆盖厚度呈线性负相关. 相似文献
7.
8.
Arthur Jeffrey L. Hachey Mark Sahr Kevin Huso Manuela Kiester A. R. 《Environmental and Ecological Statistics》1997,4(2):153-165
The problem of selecting nature reserves has received increased attention in the literature during the past decade, and a variety of approaches have been promoted for selecting those sites to include in a reserve network. One set of techniques employs heuristic algorithms and thus provides possibly sub-optimal solutions. Another set of models and accompanying algorithms uses an integer programming formulation of the problem, resulting in an optimization problem known as the Maximal Covering Problem, or MCP. Solution of the MCP provides an optimal solution to the reserve site selection problem, and while various algorithms can be employed for solving the MCP they all suffer from the disadvantage of providing a single optimal solution dictating the selection of areas for conservation. In order to provide complete information to decision makers, the determination of all alternate optimal solutions is necessary. This paper explores two procedures for finding all such solutions. We describe the formulation and motivation of each method. A computational analysis on a data set describing native terrestrial vertebrates in the state of Oregon illustrates the effectiveness of each approach. 相似文献
9.
用压实法防止煤矸石山自燃 总被引:4,自引:0,他引:4
本文分析了阳泉矿务局煤矸石山自燃的原因及几种灭火方法的适应性,介绍了碾压复盖法灭火技术在二矿矸石山取得成功的实例及分层压实法排矸工艺在五矿矸石山成功实施的实例,并认为煤矸石的资源化更为重要,更有前景。 相似文献
10.
JANINE BOLLIGER THOMAS C. EDWARDS JR. STEFAN EGGENBERG SASCHA ISMAIL IRMI SEIDL FELIX KIENAST 《Conservation biology》2011,25(3):567-576
Abstract: Abandonment of agricultural land has resulted in forest regeneration in species‐rich dry grasslands across European mountain regions and threatens conservation efforts in this vegetation type. To support national conservation strategies, we used a site‐selection algorithm (MARXAN) to find optimum sets of floristic regions (reporting units) that contain grasslands of high conservation priority. We sought optimum sets that would accommodate 136 important dry‐grassland species and that would minimize forest regeneration and costs of management needed to forestall predicted forest regeneration. We did not consider other conservation elements of dry grasslands, such as animal species richness, cultural heritage, and changes due to climate change. Optimal sets that included 95–100% of the dry grassland species encompassed an average of 56–59 floristic regions (standard deviation, SD 5). This is about 15% of approximately 400 floristic regions that contain dry‐grassland sites and translates to 4800–5300 ha of dry grassland out of a total of approximately 23,000 ha for the entire study area. Projected costs to manage the grasslands in these optimum sets ranged from CHF (Swiss francs) 5.2 to 6.0 million/year. This is only 15–20% of the current total estimated cost of approximately CHF30–45 million/year required if all dry grasslands were to be protected. The grasslands of the optimal sets may be viewed as core sites in a national conservation strategy. 相似文献