全文获取类型
收费全文 | 343篇 |
免费 | 29篇 |
国内免费 | 124篇 |
专业分类
安全科学 | 35篇 |
废物处理 | 5篇 |
环保管理 | 98篇 |
综合类 | 222篇 |
基础理论 | 66篇 |
污染及防治 | 33篇 |
评价与监测 | 12篇 |
社会与环境 | 11篇 |
灾害及防治 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 12篇 |
2020年 | 10篇 |
2019年 | 17篇 |
2018年 | 9篇 |
2017年 | 27篇 |
2016年 | 27篇 |
2015年 | 19篇 |
2014年 | 19篇 |
2013年 | 28篇 |
2012年 | 37篇 |
2011年 | 32篇 |
2010年 | 24篇 |
2009年 | 27篇 |
2008年 | 22篇 |
2007年 | 19篇 |
2006年 | 17篇 |
2005年 | 16篇 |
2004年 | 20篇 |
2003年 | 15篇 |
2002年 | 9篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有496条查询结果,搜索用时 15 毫秒
491.
492.
Frank J. Schenck Vinetta Howard‐King 《Journal of environmental science and health. Part. B》2013,48(1):1-12
Abstract A multiresidue solid‐phase extraction (SPE) method for the isolation and subsequent gas Chromatographie determination of organochlorine and organophosphorus pesticide residues in low‐moisture, nonfatty products is described. Residues are extracted from samples with an acetonitrile/water mixture. Cleanup of the extract is performed using graphitized carbon black and anion exchange SPE columns, and analysis is performed by gas chromatography with Hall electrolytic conductivity and flame photometric detection. Recovery data was obtained by fortifying corn, oats and wheat with pesticides. The average recoveries were 79–123% for eight organochlorine and 51–122% for 28 organophosphorus pesticide residues. The limit of quantitation for chlorpyriphos was 0.05 ppm using the Hall electrolytic conductivity detector and <0.005 ppm using the flame photometric detector. 相似文献
493.
草坪是城市绿地系统的重要组成部分,为量化其在城市碳平衡中的作用,采用静态箱 气相色谱法对上海结缕草草坪CO2排放通量进行了研究。结果表明:CO2排放通量具有明显的日变化和季节变化特征,日变化表现为昼高夜低的特点,最大排放通量一般出现在正午前后,最小在清晨,最大日较差为1 1877 mg/(m2·h)(7月1日),最小892 mg/(m2·h)(1月3日)。CO2排放通量的季节变化呈单峰型,夏季7月最大,春秋季次之,冬季1月最小,与温度的季节变化一致。观测期间年平均CO2排放通量为6194 mg/(m2·h)。对上海城市结缕草草坪观测期间,温度是CO2排放通量变化的主要影响因素。研究成果不仅可为城市草坪碳排放提供基础数据,也可为城市碳循环研究和管理提供参考. 相似文献
494.
Seasonal change detection of riparian zones with remote sensing images and genetic programming in a semi-arid watershed 总被引:3,自引:0,他引:3
Riparian zones are deemed significant due to their interception capability of non-point source impacts and the maintenance of ecosystem integrity region wide. To improve classification and change detection of riparian buffers, this paper developed an evolutionary computational, supervised classification method--the RIparian Classification Algorithm (RICAL)--to conduct the seasonal change detection of riparian zones in a vast semi-arid watershed, South Texas. RICAL uniquely demonstrates an integrative effort to incorporate both vegetation indices and soil moisture images derived from LANDSAT 5 TM and RADARSAT-1 satellite images, respectively. First, an estimation of soil moisture based on RADARSAT-1 Synthetic Aperture Radar (SAR) images was conducted via the first-stage genetic programming (GP) practice. Second, for the statistical analyses and image classification, eight vegetation indices were prepared based on reflectance factors that were calculated as the response of the instrument on LANDSAT. These spectral vegetation indices were then independently used for discriminate analysis along with soil moisture images to classify the riparian zones via the second-stage GP practice. The practical implementation was assessed by a case study in the Choke Canyon Reservoir Watershed (CCRW), South Texas, which is mostly agricultural and range land in a semi-arid coastal environment. To enhance the application potential, a combination of Iterative Self-Organizing Data Analysis Techniques (ISODATA) and maximum likelihood supervised classification was also performed for spectral discrimination and classification of riparian varieties comparatively. Research findings show that the RICAL algorithm may yield around 90% accuracy based on the unseen ground data. But using different vegetation indices would not significantly improve the final quality of the spectral discrimination and classification. Such practices may lead to the formulation of more effective management strategies for the handling of non-point source pollution, bird habitat monitoring, and grazing and live stock management in the future. 相似文献
495.
污泥好氧堆肥预处理混合破碎机实验研究 总被引:2,自引:2,他引:0
针对污泥高温好氧堆肥技术对粒径和含水率的要求,研制开发出了污泥混合破碎机。该破碎机采用螺旋式布置弯刀,实现污泥和辅料(包括熟料和平菇渣)的混合、破碎和输送三重功能,并能连续作业。实验表明:通过调节污泥与辅料的混合比,可以满足堆肥所需的混合料粒径(20 mm)和含水率(60%左右)要求;采用V熟:V平=1∶1作辅料,破碎机污泥处理量小于7 t/h时,满足粒径和含水率要求所需的污泥/辅料体积比R为1∶(2.5~3.5);分别采用平菇渣和熟料作辅料,结果表明,与污泥混合后都可以满足堆肥要求;平菇渣起到膨松作用,需要的量相对少。 相似文献
496.
综合传统重量法与冷凝法测定废气含湿量的特点,建立冷凝-吸附法测定固定源废气含湿量,有效解决重量法与冷凝法不适用于高温、高湿条件下的测定问题。通过优化测定条件,使冷凝-吸附法测定3台不同类型固定源废气结果的RSD为1.5%~4.7%,方法再现性试验结果的RSD为4.5%。用该方法与重量法同时测定油田注汽湿蒸汽发生器及普通流化床锅炉废气含湿量,结果表明冷凝-吸附法具备更强的适用性。 相似文献