全文获取类型
收费全文 | 57篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 19篇 |
环保管理 | 10篇 |
综合类 | 17篇 |
基础理论 | 4篇 |
污染及防治 | 5篇 |
评价与监测 | 5篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2009年 | 4篇 |
2008年 | 1篇 |
2007年 | 4篇 |
2006年 | 8篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1992年 | 1篇 |
排序方式: 共有60条查询结果,搜索用时 15 毫秒
31.
Elena D. Concepción 《Conservation biology》2021,35(4):1063-1072
Urban growth is a major threat to biodiversity conservation at the global scale. Its impacts are expected to be especially detrimental when it sprawls into the landscape and reaches sites of high conservation value due to the species and ecosystems they host, such as protected areas. I analyzed the degree of urbanization (i.e., urban cover and growth rate) from 2006 to 2015 in protected sites in the Natura 2000 network, which, according to the Habitats and Birds Directives, harbor species and habitats of high conservation concern in Europe. I used data on the degree of land imperviousness from COPERNICUS to calculate and compare urban covers and growth rates inside and outside Natura 2000. I also analyzed the relationships of urban cover and growth rates with a set of characteristics of Natura sites. Urban cover inside Natura 2000 was 10 times lower than outside (0.4% vs. 4%) throughout the European Union. However, the rates of urban growth were slightly higher inside than outside Natura 2000 (4.8% vs. 3.9%), which indicates an incipient urban sprawl inside the network. In general, Natura sites affected most by urbanization were those surrounded by densely populated areas (i.e., urban clusters) that had a low number of species or habitats of conservation concern, albeit some member states had high urban cover or growth rate or both in protected sites with a large number of species or habitats of high conservation value. Small Natura sites had more urban cover than large sites, but urban growth rates were highest in large Natura sites. Natura 2000 is protected against urbanization to some extent, but there is room for improvement. Member states must enact stricter legal protection and control law enforcement to halt urban sprawl into protected areas under the greatest pressure from urban sprawl (i.e., close to urban clusters). Such actions are particularly needed in Natura sites with high urban cover and growth rates and areas where urbanization is affecting small Natura sites of high conservation value, which are especially vulnerable and concentrated in the Mediterranean region. 相似文献
32.
本文模拟人体穿着状况下的防静电无尘服与内部服装之间的摩擦,对因摩擦导致的功能性变化进行了研究。通过实验发现,随着摩擦次数的增加,服装上的静电压有增大的趋势,从而导致防静电功能的下降。对于用长丝制作的服装,防尘性能与透气性有着直接的联系,通过透气性测试发现,服装的防尘性能随着摩擦次数的增加逐渐下降。结合防静电无尘服的使用情况,就可以确定防静电无尘服的防尘功能变化趋势及其安全使用周期。 相似文献
33.
34.
Zeinab Tavasoli Parviz Abdolmaleki Seyed Javad Mowla Faezeh Ghanati Amir Sabet Sarvestani 《The Environmentalist》2009,29(2):220-224
This research was carried out to evaluate the influence of static magnetic field on the rate of apoptosis in bone marrow stem
cells (BMSCs) of rats. Extracted cells were suspended in αMEM as a culture media for 48 h. After that, cells were exposed
to 15 mT static magnetic field (SMF) for 5 h, incessantly with or without FeCl2. The rate of apoptosis was then assessed via flow cytometery. The results showed that either treatment with FeCl2 or exposure to SMF enhanced the rate of apoptotic cells. Moreover, cells that were treated simultaneously with FeCl2 and SMF have higher rate of apoptosis. An increase in apoptosis by 26.5% was induced by SMF alone and an increase in apoptosis
by 28.2% was induced by a combination of FeCl2 and SMF, compared to their corresponding controls. The results recommended that the effects of SMF on apoptosis may be related
to increment of the number of free radicals in the cells. 相似文献
35.
Experimentally induced acute inflammation in rats is a good model system which includes the complexity and dynamics of the
processes; moreover there are many defined markers for following and estimating changes in an observed system. In this paper,
we discuss an in vivo model of acute inflammation induced by carrageenan. Carrageenan-induced paw edema is a model of non-infectious
acute inflammatory reaction to assess the contribution of mediators involved in vascular changes associated with acute inflammation
and potential treatments. A complex approach into the investigation of possible effects of static magnetic fields (SMF) action
on experimentally induced acute inflammation in rats (by measurements of the levels of specific stress markers) is very important
in understanding the possible inflammatory mitigation effects, pain relief, and oxidative stress state of an organism. This
approach could help for better understanding of the possible mechanisms of interaction of dynamic processes such as inflammation
healing and pain relief with external SMF (25 mT at 10, 20 and 30 min exposure time). Results indicate that SMF with B = 25 mT
for 30 min diminished the inflammatory process and decreased the levels of inflammatory markers (fibrinogen) and stress markers
(ACTH, Cor) into the blood plasma in rats as when compared with sham exposed animals. The exact mechanism by which SMF contributes
to the acceleration of inflammatory healing and decrease of inflammation markers in blood plasma in rats still remains unclear.
We assume that two possible mechanisms exist. One is the direct interaction of SMF with free active oxygen forms (free radicals)
affected by their membrane processes and related with the physiological functions. Another possible mechanism might be related
to dynamic regulation of inflammation healing process. 相似文献
36.
Iftheker A. Khan Nirupam Aich A.R.M. Nabiul Afrooz Joseph R.V. Flora P. Ariette Schierz P. Lee Ferguson Tara Sabo-Attwood Navid B. Saleh 《Chemosphere》2013
Aggregate structure of covalently functionalized chiral specific semiconducting single-walled carbon nanotubes (SWNTs) was systematically studied employing static light scattering (SLS). Fractal dimensions (Df) of two specific chirality SWNTs—SG65 and SG76 with (6, 5) and (7, 6) chiral enrichments—were measured under four biological exposure media conditions, namely: Dulbecco’s Modified Eagle Medium (DMEM), Minimum Essential Medium (MEM), Roswell Park Memorial Institute (RPMI) 1640 medium, and 0.9% saline solution. The SWNTs exhibited chiral dependence on Df with SG65 showing more fractal or loosely bound aggregate structures, i.e., lower Df values (range of 2.24 ± 0.03 to 2.64 ± 0.05), compared to the SG76 sample (range of 2.58 ± 0.13 to 2.90 ± 0.08). All the Df values reported are highly reproducible, measured from multiple SLS runs and estimated with ‘random block-effects’ statistical analysis that yielded all p values to be <0.001. The key mechanism for such difference in Df between the SWNT samples was identified as the difference in van der Waals (VDW) interaction energies of these samples, where higher VDW of SG76 resulted in tighter packing density. Effect of medium type showed lower sensitivity; however, presence of di-valent cations (Ca2+) in DMEM and MEM media resulted in relatively loose or more fractal aggregates. Moreover, presence of fetal bovine serum (FBS) and bovine serum albumin (BSA), used to mimic the in vitro cell culture condition, reduced the Df values, i.e., created more fractal structures. Steric hindrance to aggregation was identified as the key mechanism for creating the fractal structures. Also, increase in FBS concentration from 1% to 10% resulted in increasingly lower Df values. 相似文献
37.
Elie Gaget Alison Johnston Diego Pavón-Jordán Aleksi S. Lehikoinen Brett K. Sandercock Alaaeldin Soultan Luka Božič Preben Clausen Koen Devos Cristi Domsa Vitor Encarnação Sándor Faragó Niamh Fitzgerald Teresa Frost Clemence Gaudard Lívia Gosztonyi Fredrik Haas Menno Hornman Tom Langendoen Christina Ieronymidou Leho Luigujõe Włodzimierz Meissner Tibor Mikuska Blas Molina Zuzana Musilová Jean-Yves Paquet Nicky Petkov Danae Portolou Jozef Ridzoň Laimonas Sniauksta Antra Stīpniece Norbert Teufelbauer Johannes Wahl Marco Zenatello Jon E. Brommer 《Conservation biology》2022,36(4):e13877
Protected area networks help species respond to climate warming. However, the contribution of a site's environmental and conservation-relevant characteristics to these responses is not well understood. We investigated how composition of nonbreeding waterbird communities (97 species) in the European Union Natura 2000 (N2K) network (3018 sites) changed in response to increases in temperature over 25 years in 26 European countries. We measured community reshuffling based on abundance time series collected under the International Waterbird Census relative to N2K sites’ conservation targets, funding, designation period, and management plan status. Waterbird community composition in sites explicitly designated to protect them and with management plans changed more quickly in response to climate warming than in other N2K sites. Temporal community changes were not affected by the designation period despite greater exposure to temperature increase inside late-designated N2K sites. Sites funded under the LIFE program had lower climate-driven community changes than sites that did not received LIFE funding. Our findings imply that efficient conservation policy that helps waterbird communities respond to climate warming is associated with sites specifically managed for waterbirds. 相似文献
38.
Considering the increased trend to use renewable energy to meet electrical energy demands, a reliable performance also should be adopted in transmitting the generated power through the stable transmission and subtransmission systems for which nowadays Flexible AC Transmission System (FACTS) controllers are used extensively. Transient stability is one of the most important issues in power system stability analysis. FACTS devices have confirmed their capabilities in various aspects in power networks. In this paper, to improve transient stability of power systems, a shunt connected FACTS devices have been introduced, i.e., Static VAR compensators (SVCs). The SVC has the most diversified branches among FACTS devices. The main aim of this work is to study and analyze the impact of eight branches of SVC on improvement of transient stability and to choose the best of them. Simulations are performed in MATLAB/SIMULINK environment. 相似文献
39.
Parviz Abdolmaleki Faezeh Ghanati Hassan Sahebjamei Amir Sabet Sarvestani 《The Environmentalist》2007,27(4):435-440
Bio-effects of static magnetic fields on cell growth and cell death have been investigated in suspension-cultured tobacco
cells as undifferentiated, embryonic plant cell model. The cells in their logarithmic growth phase were exposed to static
magnetic field with the magnitudes of 10 mT and 30 mT for 5 h/day. Exposure to static magnetic field ceased the growth and
caused an increase in cell death of exposed tobacco cells compared to those cells which were not treated with the field. Promotion
of cell death was accompanied by a harmonized increase in the activity of peroxidase and increase of lignifcation of cell
walls. 相似文献
40.