全文获取类型
收费全文 | 187篇 |
免费 | 2篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 11篇 |
废物处理 | 8篇 |
环保管理 | 20篇 |
综合类 | 32篇 |
基础理论 | 61篇 |
污染及防治 | 48篇 |
评价与监测 | 6篇 |
社会与环境 | 7篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 6篇 |
2013年 | 11篇 |
2012年 | 12篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 14篇 |
2008年 | 12篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有194条查询结果,搜索用时 125 毫秒
191.
Tonle Sap Lake is a large and complex data-deficient ecosystem in the Mekong River Basin. Highly valuable in biodiversity and natural livelihoods capital, it is susceptible to degradation when the flood pulse that drives its productivity is altered as a result of hydropower and irrigation development on the Mekong River. To date, there are no tools to assess the consequences of such flood pulse alterations, leaving the Tonle Sap underrated in water-resources use and planning. A combined ecological-hydrodynamic model is presented for the production potential of the Tonle Sap ecosystem and its likely response to hydrological changes. 相似文献
192.
The migration behavior of the actinyl ions U(VI)O22+, Np(V)O2+ and Pu(V,VI)O2(+,2+) in the geosphere is to a large extend controlled by sorption reactions (inner- or outer-sphere adsorption, ion-exchange, coprecipitation/structural incorporation) with minerals. Here NpO2+ adsorption onto calcite is studied in batch type experiments over a wide range of pH (6.0–9.4) and concentration (0.4 μM–40 μM) conditions. pH is adjusted by variation of CO2 partial pressure. Adsorption is found to be pH dependent with maximal adsorption at pH 8.3 decreasing with increasing and decreasing pH. pH dependence of adsorption decreases with increasing Np(V) concentration. EXAFS data of neptunyl adsorbed to calcite and neptunyl in the supernatant shows differences in the Np(V)-O-yl distance, 1.85 ± 0.01 Å for the adsorbed and 1.82 ± 0.01 Å for the solution species. The equatorial environment of the neptunyl in solution shows about 5 oxygen neighbours at 2.45 ± 0.02 Å. For adsorbed neptunyl there are also about 5 oxygen neighbours at 2.46 ± 0.01 Å. An additional feature in the adsorbed species' R-space spectrum can be related to carbonate neighbours, 3 to 6 carbon backscatterers (C-eq) at 3.05 ± 0.03 Å and 3 to 6 oxygen backscatterers (O-eq2) at 3.31 ± 0.02 Å. The differences in the Np(V)-O-yl distance and the C-eq and O-eq2 backscatterers which are only present for the adsorbed species indicate inner-sphere bonding of the adsorbed neptunyl species to the calcite surface. Experiments on adsorption kinetics indicate that after a fast surface adsorption process a continuous slow uptake occurs which may be explained by incorporation via surface dissolution and reprecipitation processes. This is also indicated by the part irreversibility of the adsorption as shown by increased KD values after desorption compared to adsorption. 相似文献
193.
In the environment, the sorption and the degradation of organic pollutants are of increasing interest. The investigation of the chemical structures provides a basis for the development of a suitable binding model approach and for the mechanistic understanding of the chemical fate processes. The aim of this study was the identification of different species of the antibiotic compound sulfadiazine (SDZ) using (1)H and (13)C NMR experiments and ab initio density functional theory (DFT) calculations. In the neutral, aprotic solvent dimethylsulfoxide-d(6) (DMSO-d(6)), a new sulfadiazine structure containing an O-H-N hydrogen bond was identified. In the protic solvent water-d(2) and in dependence on pH and the position of the amidogen hydrogen atom nine possible SDZ conformations were analyzed and five structures were identified. Good conformity between theory and calculation of (1)H NMR was observed. Unfortunately, (13)C NMR is not sensitive enough for comparison and differentiation. In order to verify the identified structures, additional NBO/NLMO (natural localized molecular orbital) analyses were conducted (calculation of net atomic charges, bond polarity, atomic valence, and electron delocalization). Finally, conformation optimizations were performed in order to investigate the stability of the SDZ species. We showed that SDZ contains no S=O double bond, but that it has two S-O single bonds. Surprisingly, negative charges were observed at the pyrimidine nitrogen atom. With these results, the known structure of SDZ was revised. Studies of the geometrical structure and the torsion angles showed that SDZ is very flexible and can be easily fitted to the sorbent. These observations would explain the strong sorbance and hence the rapid formation of non-extractable residues in the environment because SDZ acts as a strong ligand. These results show that that the sulfonamide hydrogen is important for the biological activity but the pyrimidine nitrogen and the sulfonamide oxygen is responsible for the sorbance in environment. 相似文献
194.
Assessing Landscape Functions with Broad-Scale Environmental Data: Insights Gained from a Prototype Development for Europe 总被引:4,自引:0,他引:4
Felix Kienast Janine Bolliger Marion Potschin Rudolf S. de Groot Peter H. Verburg Iris Heller Dirk Wascher Roy Haines-Young 《Environmental management》2009,44(6):1099-1120
We examine the advantages and disadvantages of a methodological framework designed to analyze the poorly understood relationships
between the ecosystem properties of large portions of land, and their capacities (stocks) to provide goods and services (flows).
These capacities (stocks) are referred to as landscape functions. The core of our assessment is a set of expert- and literature-driven
binary links, expressing whether specific land uses or other environmental properties have a supportive or neutral role for
given landscape functions. The binary links were applied to the environmental properties of 581 administrative units of Europe
with widely differing environmental conditions and this resulted in a spatially explicit landscape function assessment. To
check under what circumstances the binary links are able to replace complex interrelations, we compared the landscape function
maps with independently generated continent-wide assessments (maps of ecosystem services or environmental parameters/indicators).
This rigorous testing revealed that for 9 out of 15 functions the straightforward binary links work satisfactorily and generate
plausible geographical patterns. This conclusion holds primarily for production functions. The sensitivity of the nine landscape
functions to changes in land use was assessed with four land use scenarios (IPCC SRES). It was found that most European regions
maintain their capacity to provide the selected services under any of the four scenarios, although in some cases at other
locations within the region. At the proposed continental scale, the selected input parameters are thus valid proxies which
can be used to assess the mid-term potential of landscapes to provide goods and services. 相似文献