全文获取类型
收费全文 | 1504篇 |
免费 | 371篇 |
国内免费 | 423篇 |
专业分类
安全科学 | 115篇 |
废物处理 | 64篇 |
环保管理 | 92篇 |
综合类 | 787篇 |
基础理论 | 895篇 |
污染及防治 | 235篇 |
评价与监测 | 76篇 |
社会与环境 | 14篇 |
灾害及防治 | 20篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 35篇 |
2021年 | 45篇 |
2020年 | 37篇 |
2019年 | 45篇 |
2018年 | 118篇 |
2017年 | 103篇 |
2016年 | 109篇 |
2015年 | 121篇 |
2014年 | 145篇 |
2013年 | 193篇 |
2012年 | 161篇 |
2011年 | 159篇 |
2010年 | 124篇 |
2009年 | 115篇 |
2008年 | 86篇 |
2007年 | 87篇 |
2006年 | 88篇 |
2005年 | 67篇 |
2004年 | 70篇 |
2003年 | 54篇 |
2002年 | 44篇 |
2001年 | 33篇 |
2000年 | 32篇 |
1999年 | 30篇 |
1998年 | 20篇 |
1997年 | 16篇 |
1996年 | 23篇 |
1995年 | 20篇 |
1994年 | 21篇 |
1993年 | 16篇 |
1992年 | 16篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有2298条查询结果,搜索用时 593 毫秒
891.
Wang Zheng Zhang Bingru Li Fengting 《Frontiers of Environmental Science & Engineering in China》2007,1(4):454-458
The objective of this study was to prepare a new photocatalyst with high activities for degradation of organic pollutants.
Coupled ZrO2/ZnO photocatalyst was prepared with a simple precipitation method with cheap raw materials zinc acetate and zirconium oxychloride,
and was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Reactive brilliant red X-3B was
used as a model compound to investigate the photocatalytic activity of synthesized catalysts in water under 254 nm UV irradiation.
Results show that the optimal calcination temperature and coupling molar ratio of Zr were 350°C And 2.5%, respectively. At
the calcination temperature of 350°C, ZrO2 was dispersed on the surface of hexagonal ZnO in the form of amorphous clusters. The particle size of ZrO2/ZnO decreased with the decrease of calcination temperature and the increase of Zr coupling amount. ZrO2/ZnO has better photocatalytic activity for degradation of reactive brilliant red (RBR) X-3B than pure ZnO and P25-TiO2. 相似文献
892.
893.
汽车尾气和大气中C1—C4烃类分析方法研究 总被引:3,自引:0,他引:3
采用熔融性Al2O3/KCl大孔径毛细管柱,用气相色谱直接进样方式,对汽车尾气中的低碳烃类化合物进行了分析监测。在汽车尾气中检出了32个色谱峰,对其中的10种烃类化合物进行了定量测定。浓度在25μg/L-20mg/L范围内与峰面积有良好的线性关系,方法的相对标准偏差小于10%;样品的回收率为85.0%-115.0%;最低检出浓度为25μg/L。 相似文献
894.
The photocatalytic degradation of dye Rhodamine B (RhB) in the presence of TiO2 nanostdpe or P25 under visible light irradiation was investigated. The degradation intermediates were identified using Infrared spectra (IR spectra), ^1H nuclear magnetic resonance (^1HNMR) spectra, and gas chromatography-mass spectroscopy (GC-MS). The IR and the ^1HNMR results showed that the large conjugated chromophore structure of RhB was efficiently destroyed under visible light irradiation in both the photocatalytic systems (TiO2 nanostfipe or P25 and Rhodamine B systems). GC-MS results showed that the main identified intermediates were ethanediotic acid, 1,2-benzenedicarboxylic acid, 4-hydroxy benzoic acid and benzoic acid, which were almost the same in the TiO2 nanostdpes and P25 systems. This work provides a good insight into the reaction pathway(s) for the TiO2-assisted photocatalytic degradation of dye pollutants under visible light irradiation. 相似文献
895.
研究五氯酚(PCP)对稀有鮈鲫(Gobiocypris rarus)胚胎的致畸和毒性效应.以7.5,30,60,120,250μg/L5个浓度的PCP对0hpf(hpf,受精卵孵出时间)的稀有鮈鲫胚胎进行暴露染毒,同时设置空白对照组、二甲基亚砜溶剂对照组和雌二醇(EE2,2.5ng/L)阳性对照组.在立体显微镜下观察整个胚胎的发育过程,统计胚胎的孵化率、96hpf相对存活率和各时期的畸形率,并利用半定量RT-PCR检测胚胎中CYP1A基因和p53基因mRNA的表达.结果表明,PCP暴露能延迟稀有鮈鲫胚胎发育,并造成胚胎卵凝结、心包囊肿、脊柱弯曲等多种畸形甚至死亡.随着PCP暴露浓度的升高,稀有鮈鲫胚胎的孵化率和96hpf相对存活率降低,各时期的畸形率增加,并呈现一定的浓度效应.稀有鮈鲫胚胎CYP1A基因和p53基因mRNA表达被显著诱导,并随PCP浓度的升高而增加.PCP对稀有鮈鲫胚胎发育表现为显著的毒性效应.稀有鮈鲫胚胎孵化率、96hpf相对存活率、各时期畸形率及CYP1A基因和p53基因的诱导表达可以作为评价PCP毒性作用的敏感指标. 相似文献
896.
897.
以活性艳红X-3B为对象,研究其在不同波段紫外光照射条件下的光催化降解动力学.结果表明,在长波紫外条件下,活性艳红X-3B的降解动力学符合表观一级动力学方程,其反应表观速率常数与光强之间呈对数关系;在短波紫外条件下,活性艳红X-3B的降解动力学可以用二级动力学方程拟合,速率常数与光强之间成正比.通过对比X-3B在2种光源下的降解半衰期发现,在同比条件下,365 nm光源对活性艳红X-3B的降解半衰期为37.263 min,而254 nm光源则下降为0.855 min.短波紫外比长波紫外具有更高的光量子效率,其对X-3B的降解效率也更高. 相似文献
898.
Using the ionic liquid(IL)1-octyl-3-methylimidazolium hexafluorophosphate as the extractant and methanol as the dispersion solvent,a dispersive liquid–liquid microextraction method was developed to extract silver nanoparticles(AgN Ps)from environmental water samples.Parameters that influenced the extraction efficiency such as IL concentration,pH and extraction time were optimized.Under the optimized conditions,the highest extraction efficiency for AgN Ps was above 90% with an enrichment factor of 90.The extracted AgN Ps in the IL phase were identified by transmission electron microscopy and ultraviolet–visible spectroscopy,and quantified by inductively coupled plasma mass spectrometry after microwave digestion,with a detection limit of 0.01 μg/L.The spiked recovery of AgN Ps was 84.4% with a relative standard deviation(RSD)of 3.8%(n = 6)at a spiked level of 5 μg/L,and 89.7% with a RSD of 2.2%(n = 6)at a spiked level of 300 μg/L,respectively.Commonly existed environmental ions had a very limited influence on the extraction efficiency.The developed method was successfully applied to the analysis of Ag NPs in river water,lake water,and the influent and effluent of a wastewater treatment plant,with recoveries in the range of 71.0%–90.9% at spiking levels of 0.11–4.7 μg/L. 相似文献
899.
化学发光测定示踪剂罗丹明B的新方法 总被引:1,自引:0,他引:1
天然河流水质模型的扩散系数通常采用罗丹明B作示踪剂来测定。囚此,河水中罗丹明B测定的准确度对水质模型的建立和精度至关重要。本文建立了化学发光分析罗丹明B的新方法,从而消除了河水浊度的影响。 相似文献
900.
The importance of incorporating functional habitats into conservation planning for highly mobile species in dynamic systems
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)
Matthew H. Webb Aleks Terauds Ayesha Tulloch Phil Bell Dejan Stojanovic Robert Heinsohn 《Conservation biology》2017,31(5):1018-1028
The distribution of mobile species in dynamic systems can vary greatly over time and space. Estimating their population size and geographic range can be problematic and affect the accuracy of conservation assessments. Scarce data on mobile species and the resources they need can also limit the type of analytical approaches available to derive such estimates. We quantified change in availability and use of key ecological resources required for breeding for a critically endangered nomadic habitat specialist, the Swift Parrot (Lathamus discolor). We compared estimates of occupied habitat derived from dynamic presence‐background (i.e., presence‐only data) climatic models with estimates derived from dynamic occupancy models that included a direct measure of food availability. We then compared estimates that incorporate fine‐resolution spatial data on the availability of key ecological resources (i.e., functional habitats) with more common approaches that focus on broader climatic suitability or vegetation cover (due to the absence of fine‐resolution data). The occupancy models produced significantly (P < 0.001) smaller (up to an order of magnitude) and more spatially discrete estimates of the total occupied area than climate‐based models. The spatial location and extent of the total area occupied with the occupancy models was highly variable between years (131 and 1498 km2). Estimates accounting for the area of functional habitats were significantly smaller (2–58% [SD 16]) than estimates based only on the total area occupied. An increase or decrease in the area of one functional habitat (foraging or nesting) did not necessarily correspond to an increase or decrease in the other. Thus, an increase in the extent of occupied area may not equate to improved habitat quality or function. We argue these patterns are typical for mobile resource specialists but often go unnoticed because of limited data over relevant spatial and temporal scales and lack of spatial data on the availability of key resources. Understanding changes in the relative availability of functional habitats is crucial to informing conservation planning and accurately assessing extinction risk for mobile resource specialists. 相似文献