全文获取类型
收费全文 | 52篇 |
免费 | 2篇 |
国内免费 | 6篇 |
专业分类
安全科学 | 2篇 |
废物处理 | 1篇 |
环保管理 | 11篇 |
综合类 | 22篇 |
基础理论 | 9篇 |
污染及防治 | 2篇 |
评价与监测 | 2篇 |
社会与环境 | 4篇 |
灾害及防治 | 7篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2007年 | 3篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1994年 | 3篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有60条查询结果,搜索用时 31 毫秒
31.
32.
The corrosion rates of API X65 mild steel alloy in CO2 – containing produced water have been studied by weight loss technique, potentiodynamic polarization technique and characterization of the corroded surface techniques. The effect of temperature, speed of rotation, pH and acetic acid concentration were studied. The optimum condition in presence and absence of protective film were also addressed. The kinetic parameters and reaction behavior were discussed in details. Corrosion rates increases with increasing temperature, acetic acid concentration, and speed of rotation, and decreased with increasing solution pH. The primary corrosion product of API X65 mild steel is ferrous carbonate (FeCO3) at high temperatures, high pH's (alkaline media) and absence of acetic acid, which could act as a protective film so that CO2 corrosion rate can be reduced. 相似文献
33.
本文对长江上游雅砻江一带的藏、汉、彝和纳西等民族混合居住地区的文化、社会、生产、生活习俗,地形、地质、地貌演变,以及森林砍伐,乱开矿山,随意捕杀动物等人为活动,造成了水土流失、滑坡、泥石流和地震等自然灾害。破坏了自然生态环境,给当地开发丰富的水资源和矿产资源带来了极大的影响。 相似文献
34.
Deflector Designs for Fish Habitat Restoration 总被引:1,自引:0,他引:1
Paired current deflectors are structures that are installed on each bank of a river to locally reduce the width of the channel, thereby creating flow acceleration and promoting scouring. These instream habitat structures have been used extensively in restoration projects to create pool habitat for fish, but there are many discrepancies in deflector design recommendations in terms of orientation, height, and length. Our objectives were to (1) examine how the angle, height, and length of paired deflectors affect scour hole dimensions and potential for bank erosion; and (2) test the applicability to paired deflectors of existing equations for scour hole depth and volume. Three deflector angles (45°, 90°, and 135°), two deflector heights (with flow under and over the deflector height), and two lengths (reducing the width by 25% and 50%) were investigated using uniform sand in a laboratory flume. Results showed a 26–30% smaller scour depth resulting from 45° deflectors than from 90° deflectors and a 5–10% smaller scour depth for 135° deflectors compared to 90° deflectors. The volume of scour and the potential for bank erosion were greater when flow was under the height of the deflectors rather than overtopping and when the length of deflector was increased. When flow was under the deflector height, 135° deflectors had the highest amount of bank erosion; whereas during overtopping flow conditions, 90° deflectors had the greatest bank erosion potential. Values predicted by the model of Kuhnle and others were closest to observed scour depth and volume measurements. The assumption that upstream-oriented deflectors always generate the largest scour should be revised. 相似文献
35.
36.
Mingteh Chang Jack D. McCullough Alfredo B. Granillo 《Journal of the American Water Resources Association》1983,19(2):191-196
ABSTRACT: Spatial variation of five water quality variables were analyzed using composite water samples collected periodically from eight small watersheds (11.4–71.6 km2) in forested East Texas during 1977 through 1980. Based on 31 observations during the four-year period the average yield of nitrate-nitrite nitrogen (NNN), total kjeldahl nitrogen (TKN), total phosphorus (PO4), chloride (CHL), and total suspended sediment (TSS) were 1.43, 21.96, 3.09, 50.11, and 90.39 ka/ha/yr, respectively. Compared to the water quality standards of the U.S. Environmental Protection Agency (1976) and the Texas Department of Water Resources (1976) for CHL, TSS, and NNN, none of the observations exceeded the limits for public water supplies. The study showed that forested watersheds normally yielded stream flow with better quality than that from agricultural watersheds. Watersheds of greater percent of pasture area, mean slope, stream segment frequency, and drainage density produced greater concentrations for these five chemical parameters in water samples. Meaningful equations were developed for estimating mean average yields for each chemical parameter for each watershed with R2 ranging from 0.77 to 0.96 and standard error of estimates from 17 to 33 percent of the observed means. 相似文献
37.
Virtual Corridors for Conservation Management 总被引:1,自引:0,他引:1
Abstract: Corridors are usually perceived as clearly visible, linear landscape elements embedded in a hostile environment that connect two or more larger blocks of habitat. Animal response to certain aspects of landscape heterogeneity, however, can channel their movements into specific routes that may appear similar to their surroundings. These routes can be described as "virtual corridors" (VCs). Here we contribute to the foundation of the concept of VCs and highlight their implications for conservation management. We used an individual-based model to analyze the formation of VCs in the case of hilltopping in butterflies—where males and virgin females ascend to hilltops and mate. We simulated butterfly movements in two different topographically heterogeneous landscapes. We analyzed the movement patterns with respect to one parameter, the intensity of response to topography. Virtual corridor structure depended on the behavioral parameter, landscape, and location of the source patch. Within a realistic range of the behavioral parameter and in a realistic landscape, VC structures may be complex and require individual-based models for their elucidation. 相似文献
38.
Nadine Salzmann Stephan Gruber Marco Hugentobler Martin Hoelzle 《Environmental Modeling and Assessment》2007,12(4):303-313
The thawing of alpine permafrost due to changes in atmospheric conditions can have a severe impact, e.g., on the stability
of rock walls. The energy balance model, PERMEBAL, was developed in order to simulate the changes and distribution of ground
surface temperature (GST) in complex high-mountain topography. In such environments, the occurrence of permafrost depends
greatly on the topography, and thus, the digital terrain model (DTM) is an important input of PERMEBAL. This study investigates
the influence of the DTM on the modeling of the GST. For this purpose, PERMEBAL was run with six different DTMs. Five of the
six DTMs are based on the same base data, but were generated using different interpolators. To ensure that only the topographic
effect on the GST is calculated, the snow module was turned off and uniform conditions were assumed for the whole test area.
The analyses showed that the majority of the deviations between the different model outputs related to a reference DTM had
only small differences of up to 1 K, and only a few pixels deviated more than 1 K. However, we also observed that the use
of different interpolators for the generation of a DTM can result in large deviations of the model output. These deviations
were mainly found at topographically complex locations such as ridges and foot of slopes. 相似文献
39.
内蒙古典型草原土壤及其水文过程对灌丛化的响应 总被引:6,自引:2,他引:4
基于野外观测和室内试验相结合的方法,研究了内蒙古典型草原小叶锦鸡儿灌丛化过程对土壤和土壤水文过程的影响,旨在为干旱半干旱区环境保护和恢复提供理论基础。结果表明,斑块尺度上,灌丛斑块土壤有机质和全氮含量分别是草地斑块的1.54倍和1.16倍;灌丛斑块平均沙粒、粉粒和粘粒含量是草地斑块的0.87倍、1.34倍和1.35倍;灌丛斑块土壤容重是草地斑块的0.97倍;灌丛斑块钙积层上表面出现深度是草地斑块的1.27倍。地形等自然条件也是形成土壤异质性的重要因子,坡面尺度上,灌丛和草地斑块土壤有机质、全氮、土壤容重、土壤钙积层上表面出现深度呈自坡顶向坡下方向增加的趋势。染色示踪实验表明,灌丛斑块土壤剖面湿润锋和土壤水分入渗速率分别是草地斑块的1.36倍和5.16倍,草地斑块0~10cm土层对水分的响应较敏感,而灌丛斑块25 cm以下土层对水分的响应较敏感。研究认为,灌丛化过程增强了土壤空间异质性,灌丛斑块能将土壤水分快速输送并存储于深层土壤中,灌丛斑块是土壤养分和水分富集区,灌木植物的定居和发展过程与土壤形态之间形成了正反馈。 相似文献
40.
Jessica A. Salo David M. Theobald Thomas C. Brown 《Journal of the American Water Resources Association》2016,52(3):632-647
Riparian zones in semi‐arid, mountainous regions provide a disproportionate amount of the available wildlife habitat and ecosystem services. Despite their importance, there is little guidance on the best way to map riparian zones for broad spatial extents (e.g., large watersheds) when detailed maps from field data or high‐resolution imagery and terrain data are not available. Using well‐established accuracy metrics (e.g., kappa, precision, computational complexity), we evaluated eight methods commonly used to map riparian zones. Focusing on a semi‐arid, mountainous watershed, we found that the most accurate and robust method for mapping riparian zones combines data on upstream drainage area and valley topography. That method performed best regardless of stream order, and was most effective when implemented with fine resolution topographic and stream line data. Other commonly used methods to model riparian zones, such as those based on fixed‐width buffers, yielded inaccurate results. We recommend that until very‐high resolution (<1 m) elevation data are available at broad extents, models of riparian zones for semi‐arid mountainous regions should incorporate drainage area, valley topography, and quantify uncertainty. 相似文献