全文获取类型
收费全文 | 19882篇 |
免费 | 1411篇 |
国内免费 | 2896篇 |
专业分类
安全科学 | 2995篇 |
废物处理 | 462篇 |
环保管理 | 3455篇 |
综合类 | 11085篇 |
基础理论 | 1748篇 |
环境理论 | 13篇 |
污染及防治 | 1320篇 |
评价与监测 | 898篇 |
社会与环境 | 1320篇 |
灾害及防治 | 893篇 |
出版年
2024年 | 71篇 |
2023年 | 291篇 |
2022年 | 519篇 |
2021年 | 730篇 |
2020年 | 763篇 |
2019年 | 547篇 |
2018年 | 486篇 |
2017年 | 656篇 |
2016年 | 771篇 |
2015年 | 794篇 |
2014年 | 902篇 |
2013年 | 1162篇 |
2012年 | 1377篇 |
2011年 | 1478篇 |
2010年 | 1040篇 |
2009年 | 1132篇 |
2008年 | 859篇 |
2007年 | 1340篇 |
2006年 | 1357篇 |
2005年 | 1152篇 |
2004年 | 1031篇 |
2003年 | 987篇 |
2002年 | 838篇 |
2001年 | 698篇 |
2000年 | 651篇 |
1999年 | 589篇 |
1998年 | 408篇 |
1997年 | 338篇 |
1996年 | 215篇 |
1995年 | 213篇 |
1994年 | 171篇 |
1993年 | 163篇 |
1992年 | 109篇 |
1991年 | 59篇 |
1990年 | 46篇 |
1989年 | 23篇 |
1988年 | 35篇 |
1987年 | 18篇 |
1986年 | 15篇 |
1985年 | 14篇 |
1984年 | 24篇 |
1983年 | 17篇 |
1982年 | 13篇 |
1981年 | 10篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1974年 | 6篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1971年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
81.
82.
David L. Peterson 《Environmental monitoring and assessment》2000,64(1):81-91
A quantitatively robust yet parsimonious air-quality monitoring network in mountainous regions requires special attention to relevant spatial and temporal scales of measurement and inference. The design of monitoring networks should focus on the objectives required by public agencies, namely: 1) determine if some threshold has been exceeded (e.g., for regulatory purposes), and 2) identify spatial patterns and temporal trends (e.g., to protect natural resources). A short-term, multi-scale assessment to quantify spatial variability in air quality is a valuable asset in designing a network, in conjunction with an evaluation of existing data and simulation-model output. A recent assessment in Washington state (USA) quantified spatial variability in tropospheric ozone distribution ranging from a single watershed to the western third of the state. Spatial and temporal coherence in ozone exposure modified by predictable elevational relationships ( 1.3 ppbv ozone per 100 m elevation gain) extends from urban areas to the crest of the Cascade Range. This suggests that a sparse network of permanent analyzers is sufficient at all spatial scales, with the option of periodic intensive measurements to validate network design. It is imperative that agencies cooperate in the design of monitoring networks in mountainous regions to optimize data collection and financial efficiencies. 相似文献
83.
Several theoretical, analytical, and institutional difficulties have impeded the development and application of the assessment of cumulative environmental impacts. Watershed development on coastal wetlands offers an ideal context for evaluating the land disturbance target approach to cumulative impact assessment. A model land use planning system involving a time series approach was developed for Elkhorn Slough in California. The approach included four major components: evaluation of erosion susceptibility, measurement of land disturbance, establishment of a land disturbance target, and a comparison of existing and target land disturbance values. Further research is needed to test the transferability of the approach in a wide range of coastal watersheds and to verify the applicability of the methods to other cumulative impact problems. 相似文献
84.
本文从发展我国环境监测技术产业的角度论述了环境监测技术产业的主要内容,分析了我国环境监测技术产业的发展和存在的问题,对发展我国环境监测技术产业提出了建议。 相似文献
85.
86.
离子色谱分析中的几个问题探讨 总被引:7,自引:0,他引:7
在掌握离子色谱技术最新发展动态的基础上,对离子色谱的新进展、前处理新技术、常用的改善分离度方法、若干注意事项、常遇到的问题等进行了分析探讨,以期用离子色谱技术更多更好地解决实际问题. 相似文献
88.
近年来宁夏对沙尘天气的监测及对沙漠化防治对策 总被引:1,自引:0,他引:1
宁夏在全区范围内建立沙尘暴监测网络,开展对沙尘天气的应急监测。宁夏作为沙源区和沙尘过往的主要通道,2002年全区共监测沙尘天气12次,沙尘粒径多分布在大于2 1μm。为防治沙漠化,宁夏积极寻求国际间合作,采取退耕还林还草、划管封育、禁牧、把握人工降雨时机等一系列措施,加大对沙漠化的防治力度。 相似文献
89.
90.
Rice WE 《Environmental monitoring and assessment》2004,99(1-3):251-257
A sub-surface desert water harvester was constructed in the sagebrush steppe habitat of south-central Idaho, U.S.A. The desert
water harvester utilizes a buried micro-catchment and three buried storage tanks to augment water for wildlife during the
dry season. In this region, mean annual precipitation (MAP) ranges between about 150–250 mm (6″–10″), 70% of which falls during
the cold season, November to May. Mid-summer through early autumn, June through October, is the dry portion of the year. During
this period, the sub-surface water harvester provides supplemental water for wildlife for 30–90 days, depending upon the precipitation
that year. The desert water harvester is constructed with commonly available, “over the counter” materials. The micro-catchment
is made of a square-shaped, 20 mL. “PERMALON” polyethylene pond liner (approximately 22.9 m × 22.9 m = 523 m2) buried at a depth of about 60 cm. A PVC pipe connects the harvester with two storage tanks and a drinking trough. The total
capacity of the water harvester is about 4777 L (1262 U.S. gallons) which includes three underground storage tanks, a trough
and pipes. The drinking trough is refined with an access ramp for birds and small animals. The technology is simple, cheap,
and durable and can be adapted to other uses, e.g. drip irrigation, short-term water for small livestock, poultry farming
etc. The desert water harvester can be used to concentrate and collect water from precipitation and run-off in semi-arid and
arid regions. Water harvested in such a relatively small area will not impact the ground water table but it should help to
grow small areas of crops or vegetables to aid villagers in self-sufficiency. 相似文献