全文获取类型
收费全文 | 231篇 |
免费 | 20篇 |
国内免费 | 90篇 |
专业分类
安全科学 | 14篇 |
废物处理 | 3篇 |
环保管理 | 41篇 |
综合类 | 153篇 |
基础理论 | 67篇 |
污染及防治 | 12篇 |
评价与监测 | 14篇 |
社会与环境 | 25篇 |
灾害及防治 | 12篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 9篇 |
2021年 | 18篇 |
2020年 | 11篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 16篇 |
2015年 | 8篇 |
2014年 | 9篇 |
2013年 | 21篇 |
2012年 | 16篇 |
2011年 | 18篇 |
2010年 | 16篇 |
2009年 | 13篇 |
2008年 | 13篇 |
2007年 | 24篇 |
2006年 | 14篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 9篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有341条查询结果,搜索用时 343 毫秒
101.
论我国能源利用方式及大气污染防治 总被引:2,自引:0,他引:2
朱巧凤 《中国环境管理干部学院学报》2004,14(4):50-51,65
通过对我国能源结构和利用方式的论述,以及能源燃烧产生的主要大气污染物对环境影响定性和定量的分析,提出了相应的污染防治对策。 相似文献
102.
Macroinvertebrate Community Structure Along the Longitudinal Gradient of an Agriculturally Impacted Stream 总被引:7,自引:0,他引:7
/ Lapwai Creek, an agriculturally impacted stream in northern Idaho, was sampled seasonally over a two-year period to determine if macroinvertebrate community composition changed along the longitudinal gradient and if changes followed predictions of the river continuum concept. Possible relationships between changes in food resource availability and community structure were also examined. Benthic invertebrates were collected at eight locations along the longitudinal gradient of Lapwai Creek using a Hess sampler. Random skewer analysis suggested there was no longitudinal gradient for either number of individuals or functional feeding group composition. Cluster analysis revealed that all locations, excluding a site receiving outflow from a small, eutrophic reservoir, had a similar community structure, further suggesting that invertebrate community composition remained consistent along the longitudinal gradient of the stream. The community was dominated at all sites, excluding the site below the reservoir, by functionalgrazers. Shredders were rare throughout Lapwai Creek, even in areas where healthy riparian vegetation still remained. Studies of other streams within the drainage basin show that many species found in the upper reaches of these streams, where agricultural impacts are low, were absent throughout the length of Lapwai Creek. Data collected concurrently with macroinvertebrates indicated that the input, storage, and transport of particulate organic matter was low throughout the stream, whereas periphyton abundance was high. The absence of longitudinal changes, despite flowing through three distinct geomorphological regions, and the grouping of all sites except one by cluster analysis for both dominant taxa and functional feeding groups suggest that agricultural alteration has influenced community structure of Lapwai Creek, resulting in a relatively homogeneous assemblage of macroinvertebrates capable of tolerating agricultural nonpoint source pollution. Additional support for this hypothesis is the high abundance of one food source, periphyton, and the small quantities of terrestrially derived organic matter. The abundance of the former and the rarity of the latter can be attributed to alteration of the drainage basin resulting from agricultural activities through inputs of fertilizers that generated high nutrient concentrations and the removal of riparian vegetation to clear more land for agriculture and provide increase access to the stream.KEY WORDS: Agriculture; Longitudinal patterns; Macroinvertebrates; Nonpoint source; River continuum 相似文献
103.
近五年中国自然灾害空间分布格局及其月动态变化研究 总被引:5,自引:7,他引:5
作者根据《中国减灾》所载1990~1994年月灾情记录,经统一编码和标准化处理,建立了以行政县为基本单元的数据库。进而对近五年来中国自然灾害空间分布及其月动态变化进行分析,并与1949~1990年中国自然灾害的平均状况进行对比。 相似文献
104.
Numerous backcountry and wilderness use studies have been conducted over the last decade, but nearly all of them have concentrated on peak season and summer use. This study investigates use patterns and user characteristics of winter campers, and implications for the management of winter backcountry overnight use. Use pattern data were collected from 580 backcountry use permits for both winter and summer campers of Great Smoky Mountains National Park (GSMNP). A two-page questionnaire was also mailed to 300 of the winter users to survey their characteristics, past backpacking experience, and reasons for winter camping. Backcountry permit data indicate that use patterns differ significantly between winter and summer campers, with winter campers taking shorter, weekend, destination-type trips. Winter campers engage in backcountry camping nearly twice as often during winter as other seasons of the year, both in and outside GSMNP. They are also experienced hikers that tend to avoid camping in Great Smoky Mountains National Park during the summer because of heavy visitor use. This suggests that winter backcountry campers are different enough from peak season campers that management of these two user groups may require different styles. 相似文献
105.
106.
Ramsis B. Salama Richard Silberstein Daniel Pollock 《Water, Air, & Soil Pollution: Focus》2005,5(1-2):3-26
The flow pathways of water in the soils of the Gnangara Mound are highly irregular and depend upon the moisture content, the
repellency and preferential wettability potential of the soils. The occurrence of preferential flow is more evident in dry
soils. As the soil wets during the rainy season, the water repellence and differential wettability decreases, the fingering
and the preferential flow paths disappear. Most of the agricultural sites in the Spearwood Sands which showed more irregular
flow than the Bassendean Sands are under continuous irrigation during cultivation season. As the repellency problems are chemically
treated, it is therefore expected that the flow will be more uniform all the year round. Landuse is mainly responsible for
variation in recharge rates; however, the hydraulic properties control aquifer response and water level pattern to a greater
degree. Water levels in the mid 1970s were in a semi steady state. Since that time, a combination of increasing water use
by pine plantations, heavy pumping from private boreholes in market gardens and private homes and intensive pumping from the
Gnangara Mound for the metropolitan water supply have caused water levels to continually decline in the Superficial aquifer.
Nitrate and phosphate concentrations in the regional Superficial aquifer are generally very low. None of the tested pesticides
(atrazine, diazinon, dimethoate, endosulfan, fenamiphos, iprodione, malathion and chlorpyrifos) were detected in the groundwater
samples collected from the monitoring bores. 相似文献
107.
A. Alexiou P. Kostarakis V. N. Christofilakis T. Zervos A. A. Alexandridis K. Dangakis C. Soras V. V. Petrović B. M. Kolundžija A. R. Dordević 《The Environmentalist》2005,25(2-4):215-221
Summary The performance of a cellular phone commercial helical antenna at 900~MHz band, both in free space and in the presence of
a human head phantom was studied. Numerical simulation of the phone model for the latter case has been performed giving 3D
radiation diagrams. The effect of the phantom head on radiation diagrams is presented. The relative amount of the EM power
absorbed in the head was obtained for several distances of the phone. Measurements were carried out in a RF anechoic chamber
using standard horn antennas and a calibrated measuring system. Absolute radiation patterns of the antenna gain were obtained
in the three principal planes. Significant reduction of the absorbed power could be achieved just by moving the phone 1 cm
away from the head. 相似文献
108.
对2004年7月13-20日西北地区东部出现的一次低涡切变型区域性冰雹天气过程,从其产生的大气环流背景和前期气候背景进行了讨论,并利用MICAPS提供的方法,对物理量场进行了初步分析,总结了其发生发展的客观规律。结果表明:形成这次连续性降雹的影响系统是500 hPa位于青藏高原东北侧到华北的低涡切变;深厚的不稳定层结和随高度增强的不稳定能量,是此次强对流发生的热力条件;有利的低层辐合与高层辐散的散度场是此次强对流发生的动力因子;随高度增强的上升运动为冰雹的形成提供了水汽条件。 相似文献
109.
110.
Johnson DL 《Environmental geochemistry and health》2008,30(6):589-596
This work introduces a spatially resolved quantitative model, based on conservation of mass and first order transfer kinetics,
for following the transport and redistribution of outdoor soil to, and within, the indoor environment by track-in on footwear.
Implementations of the DIRT model examined the influence of room size, rug area and location, shoe size, and mass transfer
coefficients for smooth and carpeted floor surfaces using the ratio of mass loading on carpeted to smooth floor surfaces as
a performance metric. Results showed that in the limit for large numbers of random steps the dual aspects of deposition to
and track-off from the carpets govern this ratio. Using recently obtained experimental measurements, historic transport and
distribution parameters, cleaning efficiencies for the different floor surfaces, and indoor dust deposition rates to provide
model boundary conditions, DIRT predicts realistic floor surface loadings. The spatio-temporal variability in model predictions
agrees with field observations and suggests that floor surface dust loadings are constantly in flux; steady state distributions
are hardly, if ever, achieved.
A contribution from ESF Center for the Urban Environment. 相似文献