全文获取类型
收费全文 | 141篇 |
免费 | 69篇 |
国内免费 | 50篇 |
专业分类
安全科学 | 9篇 |
废物处理 | 4篇 |
环保管理 | 11篇 |
综合类 | 92篇 |
基础理论 | 88篇 |
污染及防治 | 25篇 |
评价与监测 | 16篇 |
社会与环境 | 6篇 |
灾害及防治 | 9篇 |
出版年
2023年 | 5篇 |
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 62篇 |
2017年 | 13篇 |
2016年 | 14篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 17篇 |
2012年 | 10篇 |
2011年 | 8篇 |
2010年 | 14篇 |
2009年 | 11篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1985年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有260条查询结果,搜索用时 187 毫秒
41.
通过浸渍法将铁盐负载于静电纺丝纤维膜制备了类Fenton催化剂,并通过扫描电子显微镜(SEM)对静电纺丝膜进行了表征,研究了该催化剂降解双氯芬酸钠的特性及其重复利用率。结果表明,静电纺丝纤维膜反应前后膜结构良好,反应过程中铁离子几乎无溶出;膜对双氯芬酸钠有一定的吸附能力,去除率约为6.96%。当双氯芬酸钠初始浓度为20 mg·L-1,按0.310 g·(100 mL)-1比例加入催化剂时,H2O2最佳用量为340 mg·L-1。溶液的初始pH值对实验结果影响较大,酸性条件更利于双氯芬酸钠的降解,最佳pH值为3.14,但该催化剂所适用的pH值范围较之传统Fenton法有明显拓展。所制备的催化剂重复利用率高,循环使用4次后,催化活性无明显改变,4 h的去除率依然高达95%以上。反应中双氯芬酸钠主要生成乙酸等小分子化合物,最终可氧化为CO2和H2O。 相似文献
42.
为研究四溴二苯醚(BDE-47)对原代培养人甲状腺细胞功能的影响,分别用浓度为10-12、10-10和10-8mol·L-1的BDE-47处理原代人甲状腺滤泡上皮细胞(TEC)24h,采用化学发光酶联免疫检测法检测细胞上清液中甲状腺球蛋白(Tg)的浓度,半定量逆转录聚合酶链反应技术检测功能相关的Tg基因和双链复合蛋白8(Pax-8)基因的表达.结果表明,10-12、10-10mol·L-1暴露组Tg分泌量较对照组显著减少(p<0.05),而10-8mol·L-1BDE-47组Tg分泌量与对照组无显著性差异(p>0.05).甲状腺功能相关Tg基因和Pax-8基因的表达量随BDE-47浓度的增加而显著降低(p<0.05),呈明显的剂量-效应关系.以上结果提示,BDE-47对离体培养的原代人甲状腺细胞的功能具有抑制作用,甲状腺功能相关Tg基因和Pax-8基因的表达下调可能是其作用机制之一. 相似文献
43.
Assessments of risk to biodiversity often rely on spatial distributions of species and ecosystems. Range‐size metrics used extensively in these assessments, such as area of occupancy (AOO), are sensitive to measurement scale, prompting proposals to measure them at finer scales or at different scales based on the shape of the distribution or ecological characteristics of the biota. Despite its dominant role in red‐list assessments for decades, appropriate spatial scales of AOO for predicting risks of species’ extinction or ecosystem collapse remain untested and contentious. There are no quantitative evaluations of the scale‐sensitivity of AOO as a predictor of risks, the relationship between optimal AOO scale and threat scale, or the effect of grid uncertainty. We used stochastic simulation models to explore risks to ecosystems and species with clustered, dispersed, and linear distribution patterns subject to regimes of threat events with different frequency and spatial extent. Area of occupancy was an accurate predictor of risk (0.81<|r|<0.98) and performed optimally when measured with grid cells 0.1–1.0 times the largest plausible area threatened by an event. Contrary to previous assertions, estimates of AOO at these relatively coarse scales were better predictors of risk than finer‐scale estimates of AOO (e.g., when measurement cells are <1% of the area of the largest threat). The optimal scale depended on the spatial scales of threats more than the shape or size of biotic distributions. Although we found appreciable potential for grid‐measurement errors, current IUCN guidelines for estimating AOO neutralize geometric uncertainty and incorporate effective scaling procedures for assessing risks posed by landscape‐scale threats to species and ecosystems. 相似文献
44.
Protected areas (PAs) are a frequently used conservation strategy, yet their socioeconomic impacts on local communities remain contentious. A shift toward increased participation by local communities in PA governance seeks to deliver benefits for human well‐being and biodiversity. Although participation is considered critical to the success of PAs, few researchers have investigated individuals’ decisions to participate and what this means for how local people experience the costs and benefits of conservation. We explored who participates in PA governance associations and why; the perceived benefits and costs to participation; and how costs and benefits are distributed within and between communities. Methods included 3 focus groups, 37 interviews, and 217 questionnaire surveys conducted in 3 communities and other stakeholders (e.g., employees of a nongovernmental organization and government officials) in PA governance in Madagascar. Our study design was grounded in the theory of planned behavior (TPB), the most commonly applied behavior model in social psychology. Participation in PA governance was limited by miscommunication and lack of knowledge about who could get involved and how. Respondents perceived limited benefits and high costs and uneven distribution of these within and between communities. Men, poorer households, and people in remote villages reported the highest costs. Our findings illustrate challenges related to comanagement of PAs: understanding the heterogeneous nature of communities; ensuring all households are represented in governance participation; understanding differences in the meaning of forest protection; and targeting interventions to reach households most in need to avoid elite capture. 相似文献
45.
Effects of age and sex ratios on offspring recruitment rates in translocated black rhinoceros
下载免费PDF全文
![点击此处可从《Conservation biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jay V. Gedir Peter R. Law Pierre du Preez Wayne L. Linklater 《Conservation biology》2018,32(3):628-637
Success of animal translocations depends on improving postrelease demographic rates toward establishment and subsequent growth of released populations. Short‐term metrics for evaluating translocation success and its drivers, like postrelease survival and fecundity, are unlikely to represent longer‐term outcomes. We used information theory to investigate 25 years of data on black rhinoceros (Diceros bicornis) translocations. We used the offspring recruitment rate (ORR) of translocated females—a metric integrating survival, fecundity, and offspring recruitment at sexual maturity—to detect determinants of success. Our unambiguously best model (AICω = 0.986) predicted that ORR increases with female age at release as a function of lower postrelease adult rhinoceros sex ratio (males:females). Delay of first postrelease reproduction and failure of some females to recruit any calves to sexual maturity most influenced the pattern of ORRs, and the leading causes of recruitment failure were postrelease female death (23% of all females) and failure to calve (24% of surviving females). We recommend translocating older females (≥6 years old) because they do not exhibit the reproductive delay and low ORRs of juveniles (<4 years old) or the higher rates of recruitment failure of juveniles and young adults (4–5.9 years old). Where translocation of juveniles is necessary, they should be released into female‐biased populations, where they have higher ORRs. Our study offers the unique advantage of a long‐term analysis across a large number of replicate populations—a science‐by‐management experiment as a proxy for a manipulative experiment, and a rare opportunity, particularly for a large, critically endangered taxon such as the black rhinoceros. Our findings differ from previous recommendations, reinforce the importance of long‐term data sets and comprehensive metrics of translocation success, and suggest attention be shifted from ecological to social constraints on population growth and species recovery, particularly when translocating species with polygynous breeding systems. 相似文献
46.
The European Commission Biocidal Products Directive 98/8/EC lays down rules and procedures concerning the placing of biocidal products on the EU market. Based on the Directive, a First Review Regulation was adopted for the review of existing biocidal active substances. These substances had to be either identified or notified (two different processes) to the European Chemicals Bureau (ECB) by 28 March 2002. More than 1000 companies took part in the review programme. In total 953 different existing active substances were identified and 372 different substances were notified. This article presents an analysis of the notified substances regarding the number of notifications per substance, notifiers per substance and per Member State and number of notified substances per product type. The results are compared with data from former statistics. 相似文献
47.
48.
Development of GC capillary column for isomer-specific separation of toxic isomer of PCDDs and PCDFs in environmental samples 总被引:1,自引:0,他引:1
Analysis of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) has been performed using gas chromatography mass spectrometry (GC-MS). Analysis of the most toxic isomers, in particular, 2,3,7,8-substituted PCDD/PCDF in the presence of other isomers requires a special isomer specific capillary column or high performance liquid chromatography (HPLC) fractionation prior to GC-MS analysis. Commercially available long (>50 m) polar columns can separate 2,3,7,8-TCDD from other tetra isomers. However, those columns are not satisfactory for the analyses of total PCDD/PCDF in the environmental samples. Gas chromatography -high resolution mass spectrometry (GC-HRMS) and GC-MS/MS techniques are not helpful in the analysis of 2,3,7,8-TCDD unless it is separated from the other tetra isomers. The analysis of 2,3,7,8-TCDD and total PCDD and PCDF in a single GC-MS run can ease the laborious techniques presently used. In this study we have developed a new stationary phase for the GC capillary column. The capillary column developed using this new stationary phase showed unsurpassed selectivity for the separation of 2,3,7,8-TCDD from other tetra isomers. There are several advantages of the newly developed GC capillary column. 相似文献
49.
When petroleum hydrocarbons contaminate soil, the carbon:nitrogen (C:N) ratio of the soil is altered. The added carbon stimulates microbial numbers but causes an imbalance in the C:N ratio which may result in immobilization of soil nitrogen by the microbial biomass, leaving none available for plant growth. As members of Leguminosae fix atmospheric nitrogen to produce their own nitrogen for growth, they may prove more successful at growing on petroleum hydrocarbon contaminated sites. During a wider study on phytoremediation of diesel fuel contaminated soil, particular attention was given to the performance of legumes versus other plant species. During harvesting of pot experiments containing leguminous plants, a recurring difference in the number and formation of root nodules present on control and contaminated Common vetch (Vicia sativa L.) plants was observed. The total number of nodules per plant was significantly reduced in contaminated plants compared to control plants but nodules on contaminated plants were more developed than corresponding nodules on control plants. Plant performance of Common vetch and Westerwold's ryegrass (Lolium multiflorum L.) was compared to illustrate any difference between the ability of legumes and grasses to grow on diesel fuel contaminated soil. Common vetch was less affected by diesel fuel and performed better in low levels of diesel fuel contaminated soil than Westerwolds ryegrass. The total amount of diesel fuel remaining after 4 months in Common vetch planted soil was slightly less than in Westerwolds ryegrass planted soil. 相似文献
50.
研究了铜对缘管浒苔(Enteromorphalinza)的毒性效应,试验了不同的配合剂对铜的毒性效应及累积量的影响。结果发现,铜对缘管浒苔的毒性效应阈值为0.10mg/L;0.50mg/LCu ̄(2+)可使缘管浒苔迅速死亡,培养96h后光合作用强度下降为零。EDTA可抑制铜在藻体中的累积,缓解毒性;8-羟基喹啉则促进铜在藻体中的累积,加刷了毒性。和铜污染的培养介质短期接触(<1m后,加入足量EDTA,藻体生长和对照组相当,较长时间接触(>4h)后,ED-TA不能使藻恢复生长。结合EDTA“洗脱”实验提出,Cu ̄(2+)可能首先经离子交换机制结合于藻体表面,之后,才逐步向细胞内转移。 相似文献