全文获取类型
收费全文 | 2280篇 |
免费 | 95篇 |
国内免费 | 727篇 |
专业分类
安全科学 | 127篇 |
废物处理 | 153篇 |
环保管理 | 153篇 |
综合类 | 1244篇 |
基础理论 | 394篇 |
污染及防治 | 761篇 |
评价与监测 | 98篇 |
社会与环境 | 82篇 |
灾害及防治 | 90篇 |
出版年
2024年 | 1篇 |
2023年 | 21篇 |
2022年 | 99篇 |
2021年 | 73篇 |
2020年 | 59篇 |
2019年 | 60篇 |
2018年 | 78篇 |
2017年 | 91篇 |
2016年 | 85篇 |
2015年 | 107篇 |
2014年 | 158篇 |
2013年 | 184篇 |
2012年 | 164篇 |
2011年 | 180篇 |
2010年 | 145篇 |
2009年 | 114篇 |
2008年 | 123篇 |
2007年 | 114篇 |
2006年 | 126篇 |
2005年 | 101篇 |
2004年 | 80篇 |
2003年 | 92篇 |
2002年 | 78篇 |
2001年 | 92篇 |
2000年 | 96篇 |
1999年 | 91篇 |
1998年 | 90篇 |
1997年 | 62篇 |
1996年 | 67篇 |
1995年 | 65篇 |
1994年 | 42篇 |
1993年 | 40篇 |
1992年 | 27篇 |
1991年 | 14篇 |
1990年 | 16篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有3102条查询结果,搜索用时 62 毫秒
891.
污染场地不同深度土壤有机-矿质复合体中有机氯农药的分布 总被引:2,自引:0,他引:2
采用物理方法将某农药厂土壤分成4种粒径的有机-矿质复合体组分,粘粒、粉粒、细砂和粗砂,研究有机氯农药在土壤不同有机-矿质复合体组分中的分布特征及有机质含量对污染物质赋存分布的影响。结果表明,粉粒组分中污染物质六六六含量较高,粘粒组分中滴滴涕含量较高。粘粒和粉粒组分中污染物质的含量与相应的有机质含量间呈现显著相关关系,而在细砂和粗砂中这种相关性不显著。lgKoc值与污染物质含量的相关性分析结果与有机质的相关性分析结果相似。有机质可能是影响场地土壤有机氯农药分布的重要因素之一。本研究的结果可为污染场地的风险控制和环境修复提供基础依据。 相似文献
892.
Shen H Henkelmann B Rambeck WA Mayer R Wehr U Schramm KW 《Environment international》2012,38(1):73-78
Pigs accidentally given feed contaminated by dioxin-like pollutants are a serious public health issue. We have examined whether pigs with limited exposure during early periods of fattening would be categorized as non-compliant with the EU limit at slaughtering when growth-dilution, excretion and metabolism effects are considered. Sixteen female and sixteen castrated male weaned pigs were divided into four groups (e.g. DG0, DG1, DG2 and DG3) in week 2 after birth. From weeks 3 to 13, groups DG1, DG2, and DG3 pigs were fed with a polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) and polychlorinated biphenyl (PCB) mixture at dosages of 1, 10 and 100 ng-toxic equivalent (TEQ) per kg dry mass feed in capsules, respectively. From weeks 13 to 23, the animals were nourished with clear feed. Control group DG0 was always fed with clear feed. Subcutaneous fat samples were collected at weeks 13, 18 and 23 by biopsies. The pollutant residues were analyzed by high resolution gas chromatography-high resolution mass spectrometry and quantified by a 13C-isotope dilution method. The results showed the following: (1) when slaughtered at week 23, the TEQ for DG1 pigs (0.66 ± 0.21 pg/g fat) was under the EU limit of 1 pg PCDD/F-TEQ/g fat; (2) PCDD/F congener-specific first-order elimination rates were linearly correlated with their toxicity equivalency factors (TEFs), and the rates were significantly dose-dependent for the more toxic congeners (TEF ≥ 0.1). Therefore, the pigs' exposure above the EU limit during the early fattening stage did not necessarily lead to their categorization as non-compliant pork; and the residual TEQ for pork can be predicted from early exposure concentrations based on the models established here. 相似文献
893.
894.
X. Gu T. Cheng D. Xie Z. Li T. Yu H. Chen 《Atmospheric environment (Oxford, England : 1994)》2011,45(36):6607-6612
A precise estimate of polarization induced by surface is crucial for polarized remote sensing dedicated to monitoring aerosol properties over urban area. The accurate knowledge of interaction between surface and aerosol polarized reflectance is essential for accurately achieving aerosol properties. In order to study surface and aerosol polarized reflectance for aerosol retrievals over urban area, a new airborne directional polarimetric camera (DPC) with high spatial resolution (4 m at 4000 m a.g.l) was developed. The surface polarized reflectance over distinct surface covers of urban area (forest, shrub, and soil) were studied using DPC measurements during a field campaign in the Pearl River Delta (PRD), China. The large variations were found in surface polarized reflectance of distinct urban covers due to surface type variability. For all surface types, the empirical BPDF model cannot describe accurately surface polarized reflectance at all possible illumination and observation geometries. From the quantitatively study of relationship between surface and aerosol polarized contribution to DPC measurements, we show that the polarized contributions of aerosol, which optical properties were defined by ground-based measurements, are much larger than the polarized contribution of surface, and found that the polarized contribution of surface covers increases with decreasing NDVI. The effect of polarization accuracy of measurements on aerosol retrieval was also investigated using DPC measurements, and found that 0.1% polarization accuracy of measurements can be neglected when AOD is retrieved using polarized measurements. Based on the information of effects of polarized reflectance differences between distinct surface covers and polarization accuracy of polarized measurements on retrieved aerosols over urban area, we found that the accuracy of aerosol retrieval over forest covers is higher than other surface types using polarized remote sensing. 相似文献
895.
高声能密度超声波破碎污泥细胞效能的研究 总被引:1,自引:0,他引:1
采用超声波在较高声能密度下处理SBR的剩余污泥,主要考察了含固率、声能密度和作用时间对污泥细胞破碎效果的影响。结果表明,在声能密度0.5~3 W/mL内,含固率1%~1.5%的剩余污泥经超声波作用后,上清液SCOD随作用时间呈线性升高;在声能密度1~3 W/mL内,含固率0.25%~0.5%的剩余污泥经超声波作用后,上清液SCOD随作用时间呈平缓缓慢升高。高声能密度超声波更适合对较高含固率污泥的细胞破碎;此情况下,上清液SCOD增幅、NH4+-N、TN及TP升幅均与声能密度正相关。经超声波作用6 min后,污泥形态结构已破坏。 相似文献
896.
Co-composting of chicken manure, straw and dry grasses was investigated in a forced aeration system to estimate the effect of aeration rates on NH3, CH4 and N2O emissions and compost quality. Continuous measurements of gas emissions were carried out and detailed gas emission patterns were obtained using an intermittent-aeration of 30 min on/30 min off at rates of 0.01 (A1), 0.1 (A2) and 0.2 (A3) m3 min−1 m−3. Concentrations of CH4 and N2O at the low aeration rate (A1) were significantly greater than those at the other two rates, but there was no significant difference between the A2 and A3 treatments. CH4 and N2O emissions for this mixture could be controlled when the composting process was aerobic and ammonia emissions were reduced at a lower aeration rate. Comparison of CH4, N2O, NH3 emissions and compost quality showed that the aeration rate of the A2 treatment was superior to the other two aeration rates. 相似文献
897.
898.
Liu GD Gu B Miao SL Li YC Migliaccio KW Qian Y 《Journal of environmental quality》2010,39(5):1585-1593
Dead plant tissues and ash from a prescribed fire play an important role in nutrient balance and cycling in the Florida Everglades ecosystem. The objective of this study was to assess the dynamic changes in total phosphorus release (TPr) from ash or tissues of either cattail (Typha domingensis Pers.) or sawgrass (Cladium jamaicense Crantz) to water. Natural-dead (senesced-dead) and burning-dead (standing-dead due to a prescribed fire) cattail and sawgrass were collected from highly (H) and moderately (M) impacted zones in the Florida Everglades. This experiment was conducted by incubation and water-extraction of the materials in plastic bottles for 65 d at room temperature (24 +/- 1 degrees C). Results showed that 63 to 88%, 17 to 48%, 9 to 20%, and 13 to 28% of total P (TPp) were released as TPr from cattail and sawgrass ash, cattail tissues from the H zone, cattail tissues, and sawgrass tissues from the M zone, respectively. TPp means total P of plant tissues, whereas TPr is total P release from the tissues or ash. Most of the TPr was released within 24 h after burning. The quick release of TPr observed in this experiment may help explain the P surge in the surface water immediately following a fire in the marsh. These findings suggest that prescribed burning accelerates P release from cattail and sawgrass. They also imply that it is very important to keep the water stagnant in the first 24 h to maximize the benefits of a prescribed fire in the Everglades. 相似文献
899.
Hanlon EA Fan XH Gu B Migliaccio KW Li YC Dreschel TW 《Journal of environmental quality》2010,39(5):1724-1733
Restoration of the Florida Everglades is important for the health of the natural system, including both the "River of Grass" and its downstream estuaries. Water quality improvement is one indicator of successful restoration in this complex ecosystem. Using the period of record of 1977 through 2005, we evaluated data from seven inflow sites to the Everglades National Park (ENP) for temporal trends of various forms of phosphorus (P) and nitrogen (N) and analyzed them using principal component analysis and factor analysis without flow adjustments. Locally estimated scatter plot smoothing (LOESS) trend lines identified two inflection points (three time periods) of changing trend in total P (TP) concentration at the seven sites. Results indicated that overall water quality in ENP inflow improved from 1977 to 2005, with significant downward trends in TP concentration. The overall trend ofTP is probably mediated by hydrology, which is evident by a negative relationship between flow and annual average TP concentration at the majority of stations within the available data, although additional changes in vegetation due to hydroperiod may have some effects. Total N (TN), total Kjeldahl N, and total organic N concentrations also generally decreased at inflow sites. Water quality standards for TP, TN, and NH4+ -N were exceeded at selected sites during the study period. Principle component analysis and factor analysis detected a grouping of sampling sites related to the water delivery system that could be used as indicators to better manage monitoring resources. Study results suggest that water quality data analyses could provide additional insight into the success of a restoration management plan and on how monitoring may be modified for more efficient use ofresources. 相似文献
900.
Sven D. Jelaska Toni Nikolić Lucija Šerić Jelaska Vladimir Kušan Hrvoje Peternel Goran Gužvica Zoran Major 《Environmental management》2010,45(3):616-625
Here we present the methodology used for terrestrial biodiversity analysis and site selection in Phase B of the UNDP/GEF COAST
project. The analysis was focused on the problem of biodiversity evaluation in four Croatian counties stretching from sea
level to the highest mountain in Croatia. Data on habitats, vascular flora, and fauna (mammals, birds, reptiles, amphibians,
butterflies, ground beetles, and underground invertebrates) were collected and analyzed for each of the four counties. Emphasis
was given to the richness of endangered species and the rarity of endemic species. Based on the spatial analyses of habitat,
fauna, and flora data, four to six areas were selected from each county and ranked according to their biodiversity importance.
Overlap between areas important for richness and those important for rarity was highest for data on flora (65.5%) and lowest
for data on fauna (16.7%). When different data sets were compared, the lowest overlap was between flora and fauna (17.1%)
and largest between fauna and habitats (23.9%). Simultaneous overlap among all three data sets was found in just 6.5% of the
overall selected areas. These results suggest that less specific data, with respect to taxa threat status, could better serve
as surrogate data in estimating overall biodiversity. In summary, this analysis has demonstrated that Dalmatia is a region
with a high overall biodiversity that is important in a broader European context. 相似文献