全文获取类型
收费全文 | 946篇 |
免费 | 71篇 |
国内免费 | 170篇 |
专业分类
安全科学 | 79篇 |
废物处理 | 18篇 |
环保管理 | 100篇 |
综合类 | 447篇 |
基础理论 | 285篇 |
污染及防治 | 42篇 |
评价与监测 | 31篇 |
社会与环境 | 121篇 |
灾害及防治 | 64篇 |
出版年
2024年 | 3篇 |
2023年 | 9篇 |
2022年 | 27篇 |
2021年 | 31篇 |
2020年 | 34篇 |
2019年 | 34篇 |
2018年 | 38篇 |
2017年 | 44篇 |
2016年 | 46篇 |
2015年 | 42篇 |
2014年 | 44篇 |
2013年 | 55篇 |
2012年 | 68篇 |
2011年 | 72篇 |
2010年 | 68篇 |
2009年 | 57篇 |
2008年 | 54篇 |
2007年 | 80篇 |
2006年 | 66篇 |
2005年 | 59篇 |
2004年 | 46篇 |
2003年 | 17篇 |
2002年 | 21篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 25篇 |
1998年 | 17篇 |
1997年 | 11篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 18篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1187条查询结果,搜索用时 15 毫秒
11.
移动通信基站的环境电磁辐射测量与分析 总被引:1,自引:0,他引:1
选择设于上海市区及郊区的5座典型移动通信基站,对其一半电磁波辐射强度进行了规范布点监测经数据计算分析及与国家有关电磁辐射防标准比较认为,移动基站周围环境中是磁辐射强度随着离基站天线距离增加大而减少小,在人群可能到达的距天线最近的地方,辐射水平最大值为1.5V/m,未超过国家标准限值。 相似文献
12.
13.
A study on root competition in alley cropping was carried out in an agroforestry system, involving Cassia siamea Lam. and maize ( Zea mays L. cv. Katumani composite B). The existence and intensity of root competition in the top soil as manifested by the distribution of the active roots of cassia and maize, in space and time, was assessed. The root length density of maize was far greater than that of cassia in the upper 10 cm, implying that cassia was not competing with maize for water and/or nutrients at that depth. However, at maize crop tasselling and grain filling stages there was a marked overlap of roots of the two plants at lower depths (20—50 cm). This varied with distance from the cassia hedge in a way that there was a tendency for highest overlap near middle maize rows. This partly explained observed yield differences. Therefore cassia may not be a suitable choice for alley cropping with maize under semi-arid conditions on non-sloping land, unless most of its active roots can be properly managed to absorb resources below the feeding rhizosphere of the active maize roots. 相似文献
14.
Scott Murtishaw Jayant Sathaye Christina Galitsky Kristel Dorion 《Mitigation and Adaptation Strategies for Global Change》2006,11(3):645-665
The Lawrence Berkeley National Laboratory (Berkeley Lab) and the Center for Sustainable Development in the Americas (CSDA)
conducted technical studies and organized two training workshops to develop capacity in Central America for the evaluation
of climate change projects. This paper describes the results of two baseline case studies conducted for these workshops, one
for the power sector and one for the cement industry, that were devised to illustrate certain approaches to baseline setting.
Multiproject baseline emission rates (BERs) for the main Guatemalan electricity grid were calculated from 2001 data. In recent
years, the Guatemalan power sector has experienced rapid growth; thus, a sufficient number of new plants have been built to
estimate viable BERs. We found that BERs for baseload plants offsetting additional baseload capacity ranged from 0.702 kgCO2/kWh
(using a weighted average stringency) to 0.507 kgCO2/kWh (using a 10th percentile stringency), while the baseline for plants
offsetting load-following capacity is lower at 0.567 kgCO2/kWh. For power displaced from existing load-following plants, the
rate is higher, 0.735 kgCO2/kWh, as a result of the age of some plants used for meeting peak loads and the infrequency of
their use. The approved consolidated methodology for the Clean Development Mechanism yields a single rate of 0.753 kgCO2/kWh.
Due to the relatively small number of cement plants in the region and the regional nature of the cement market, all of Central
America was chosen as the geographic boundary for setting cement industry BERs. Unfortunately, actual operations and output
data were unobtainable for most of the plants in the region, and many data were estimated. Cement industry BERs ranged from
205 kgCO2 to 225 kgCO2 per metric ton of cement. 相似文献
15.
16.
4—氯苯甲酸钠的光催化氧化降解及其影响因素 总被引:8,自引:0,他引:8
本试验采用P-25TiO2,光催化剂,对4-氯苯甲酸钠的光催化氧化降解及污染物初始浓度,催化剂投加量和入射光强等因素的影响进行了研究,研究发现污染物初始降解速率与其初始浓度的关系遵循Langmuir-Hinshelwood模式,其中半饱和浓度常数Ks不仅是催化剂和污染物种类的函数,而且也是入射光强的函数,催化剂投加量存在一限值,当低于此限值时,污染物降解速率由于催化剂浓度的不足受到影响而下降,当高于此限值时,污染物降解速率受催化剂投加量的影响变小,在本试验4-CBA-Na浓度为0.15-0.6mmol/L时该催化剂限值浓度大约为0.4g/L,在入射光强为1-7mW/cm^2和催化剂浓度为0.4g/L下,污染物降解速率与光强成0.67次幂关系,经估算其量子效率为6.3%。 相似文献
17.
氯气和光气爆燃事故源强估算 总被引:2,自引:2,他引:2
在建立化学品泄漏的气体排放、液体排放、两相排放模式和爆炸燃烧的火球和气爆,蒸气云爆炸及绝热扩散和池蒸发扩展等模式的基础上,估计分析了氯气和光气爆燃事故源强,即爆炸能量及碎片抛射、冲击波、热辐射和毒云等后果影响 相似文献
18.
塔克拉玛干沙漠腹地沙尘暴特征--以塔中地区为例 总被引:13,自引:2,他引:13
塔克拉玛干沙漠是中国油气开发的重要区域,沙尘暴是该区域重要的灾害性天气,但以往相关的研究很少。为了了解塔克拉玛干沙漠腹地沙尘暴的发生规律,利用塔中气象站1997-2002年的气象资料,对塔中地区沙尘暴的强度、过程、类型和时间变化等特征进行了分析。研究结果表明:(1)塔中年平均沙尘暴日数为16.83d,较沙漠北缘的轮台和沙漠南缘的民丰、和田为多,体现出沙尘源对沙尘暴发生的影响;(2)沙尘暴发生之前出现明显的风速突然降低和风向转换;(3)同塔里木盆地其它区域一样,塔中沙尘暴也可分为5种类型,其主导类型为冷空气东灌型;(4)沙尘暴时间变化规律明显,且从20世纪90年代至21世纪初,塔中沙尘暴日数与持时明显下降,同全疆的变化趋势一致。 相似文献
19.
针对传统的污染排放数据指标计算方法存在的问题,提出污染物排放指标应根据排污强度和经济指标确定的新思路,同时提出污染物排放指标数据的快速测算模型设计.建议通过环境监测数据或物料衡算数据确定每个排污单位的平均排污强度,作为计算机处理的参数,再由该排污单位申报每月的经济指标(产量或产值),输入计算机计算其产污量、排污量和去除量.实施计算机管理的关键是选取适当的数据计算模型.新思路应该能够规范计算程序,建立污染源动态数据库,对排污数据实行有效的统计分析. 相似文献
20.
Ben C. Scheele David A. Hunter Laura A. Brannelly Lee F. Skerratt Don A. Driscoll 《Conservation biology》2017,31(3):592-600
Emerging wildlife pathogens are an increasing threat to biodiversity. One of the most serious wildlife diseases is chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd), which has been documented in over 500 amphibian species. Amphibians vary greatly in their susceptibility to Bd; some species tolerate infection, whereas others experience rapid mortality. Reservoir hosts—species that carry infection while maintaining high abundance but are rarely killed by disease—can increase extinction risk in highly susceptible, sympatric species. However, whether reservoir hosts amplify Bd in declining amphibian species has not been examined. We investigated the role of reservoir hosts in the decline of the threatened northern corroboree frog (Pseudophryne pengilleyi) in an amphibian community in southeastern Australia. In the laboratory, we characterized the response of a potential reservoir host, the (nondeclining) common eastern froglet (Crinia signifera), to Bd infection. In the field, we conducted frog abundance surveys and Bd sampling for both P. pengilleyi and C. signifera. We built multinomial logistic regression models to test whether Crinia signifera and environmental factors were associated with P. pengilleyi decline. C. signifera was a reservoir host for Bd. In the laboratory, many individuals maintained intense infections (>1000 zoospore equivalents) over 12 weeks without mortality, and 79% of individuals sampled in the wild also carried infections. The presence of C. signifera at a site was strongly associated with increased Bd prevalence in sympatric P. pengilleyi. Consistent with disease amplification by a reservoir host, P. pengilleyi declined at sites with high C. signifera abundance. Our results suggest that when reservoir hosts are present, population declines of susceptible species may continue long after the initial emergence of Bd, highlighting an urgent need to assess extinction risk in remnant populations of other declined amphibian species. 相似文献