全文获取类型
收费全文 | 1306篇 |
免费 | 32篇 |
国内免费 | 20篇 |
专业分类
安全科学 | 55篇 |
废物处理 | 68篇 |
环保管理 | 129篇 |
综合类 | 285篇 |
基础理论 | 228篇 |
环境理论 | 1篇 |
污染及防治 | 349篇 |
评价与监测 | 144篇 |
社会与环境 | 79篇 |
灾害及防治 | 20篇 |
出版年
2023年 | 10篇 |
2022年 | 16篇 |
2021年 | 30篇 |
2020年 | 17篇 |
2019年 | 17篇 |
2018年 | 38篇 |
2017年 | 49篇 |
2016年 | 43篇 |
2015年 | 31篇 |
2014年 | 62篇 |
2013年 | 93篇 |
2012年 | 45篇 |
2011年 | 80篇 |
2010年 | 54篇 |
2009年 | 65篇 |
2008年 | 73篇 |
2007年 | 69篇 |
2006年 | 50篇 |
2005年 | 54篇 |
2004年 | 60篇 |
2003年 | 72篇 |
2002年 | 49篇 |
2001年 | 53篇 |
2000年 | 31篇 |
1999年 | 25篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 5篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 16篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1970年 | 2篇 |
1962年 | 5篇 |
1961年 | 2篇 |
1938年 | 1篇 |
排序方式: 共有1358条查询结果,搜索用时 890 毫秒
441.
Karel De Greef Frans Stafleu Carolien De Lauwere 《Journal of Agricultural and Environmental Ethics》2006,19(1):57-66
Public debate on acceptable farm animal husbandry suffers from a confusion of tongues. To clarify positions of various stakeholder
groups in their joint search for acceptable solutions, the concept of animal welfare was split up into three notions: no suffering,
respect for intrinsic value, and non-appalling appearance of animals. This strategy was based on the hypothesis that multi-stakeholder
solutions should be based on shared values rather than on compromises. The usefulness of such an artificial value distinction
strategy was tested in a small series of experiments. The results demonstrate that the chosen concept to distinguish between
values is effective in a stakeholder context. Farmers’ views on doing good to animals appeared to be largely based on their
value to prevent suffering and predominantly focused on the provision of regular care. Their priority for this value is clearly
shared with other stakeholders, providing a basis for joint solutions. The concept of intrinsic value does not play a discernable
role in farmers’ considerations. Based on the varying views on welfare, it can be inferred that there is a gradual rather
than a principal difference between government legislation and farmers’ values, whereas public perception and acceptance of
farm practices remains complicated. Distinction between value groups and focusing on a selected notion (such as no suffering)
proved to be effective in bringing representatives of stakeholder groups together, but is unlikely to bridge the emotional
gap between commercial farm practices and public ideals. 相似文献
442.
443.
Investigation of the Aerobic Biodegradability of Several Types of Cyclodextrins in a Laboratory-Controlled Composting Test 总被引:1,自引:0,他引:1
Steven Verstichel Bruno De Wilde Eva Fenyvesi József Szejtli 《Journal of Polymers and the Environment》2004,12(2):47-55
The biodegradation of several types of cyclodextrins (CDs) under laboratory-controlled composting conditions was investigated. CDs are used in a broad range of applications in food, pharmaceutical, medical, chemical, and textile industries because of their specific chemical characteristics related to their hydrophobic interior and hydrophilic exterior. The three naturally occurring cyclodextrins -CD, -CD, and -CD proved to be completely and readily biodegradable. Chemical modification of these basic compounds can have a major impact on the biodegradation rate and final biodegradation percentage. Fully acetylated -CD and -CD were found to be nonbiodegradable during 45 days of composting. Reducing the degree of acetylation had a positive effect on the biodegradation. Complete biodegradation was obtained for partially acetylated -CD with a degree of substitution (DS) of 7. The methylation (DS = 13) of -CD resulted in an undegradable compound during the 47 days composting, while (2-hydroxy)propyl--CD reached a plateau in biodegradation at a percentage of 20%. The incorporation of the antimicrobial agents imazalil and allyl-isothiocyanate into -CD had no negative impact on biodegradation, which makes these antimicrobial agents/CD complexes suitable for incorporation into biodegradable active packaging. 相似文献
444.
Van Hulle M De Cremer K Cornelis R Lameire N 《Journal of environmental monitoring : JEM》2001,3(1):86-90
Five Wistar rats were given an intraperitoneal injection of [114mIn]InCl3 during four consecutive days. One hour after the last injection the rats were sacrificed. The in vivo distribution of 114mIn was studied in the blood and in different organs. Differential centrifugation was used to study the distribution in liver, kidney and spleen homogenate. Rat serum, packed cell lysate, urine and the cytosol of liver, kidney and spleen homogenate were examined by size exclusion fast protein liquid chromatography. The results showed that serum accounts for 90% of the indium activity in whole blood. Indium is preferentially accumulated within the liver, spleen and kidney, the highest amount of 114mIn being localised in the cytosolic fraction followed by the mitochondria. Size exclusion experiments showed that, in rat serum, indium is exclusively bound to transferrin. These results differed from earlier in vitro incubation experiments of human serum with 114mIn. It was not possible, from the experiments described herein, to conclude unequivocally whether indium is bound to haemoglobin of packed cell lysate or to another high molecular mass compound. Indium is associated with the high molecular mass fraction in liver, kidney and spleen cytosol; only in kidney are small amounts of 114mIn found in the low molecular mass fraction. The in vivo inhibitory effect of indium on the delta-aminolaevulinic acid dehydratase (ALAD) enzymatic activity in red blood cells and kidney tissue, well documented by other researchers, could not be attributed to direct binding of indium with this enzyme. 相似文献
445.
对武钢一管式炉2000年3月24日发生煤气爆燃事故进行了分析,结合管式炉周围现场情况,提出了避免此类事故再发生的防范措施。 相似文献
446.
447.
Past research has revealed that team effectiveness and satisfaction suffer when teams experience relationship conflict—conflict related to interpersonal issues, political norms and values, and personal taste. This study examined how teams should respond to these conflicts. Three types of conflict responses were studied: collaborating responses, contending responses, and avoiding responses. A field study involving a heterogeneous sample of teams performing complex, non‐routine task showed that collaborating and contending responses to relationship conflict negatively relate to team functioning (i.e., voice, compliance, helping behavior) and overall team effectiveness, while avoiding responses were associated with high team functioning and effectiveness. It is suggested that collaborating and contending responses to relationship conflict distract team members from their tasks, while avoiding responses appear more functional in that they allow team members to pursue task performance. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
448.
Metacommunity structure of pond macroinvertebrates: effects of dispersal mode and generation time 总被引:1,自引:0,他引:1
A recent challenge in community ecology is to understand under what conditions local and regional processes may be more important in shaping community structure. We investigated the role of dispersal mode and generation time for communities of macroinvertebrates in two sets of connected ponds during three consecutive years. We found no evidence that generation time affected metacommunity structure, possibly because statistical power was limited because the range of generation times present was small. In contrast, we found that the spatial structure of the macroinvertebrate metacommunities differed with dispersal mode in one of two sets of ponds. Passive dispersers showed positive distance-dissimilarity correlations, suggesting mass effects via the pond connections. These correlations did not stretch beyond the first pond downstream suggesting that, in this chain of connected ponds, intervening ponds effectively buffered dispersal. Active dispersers did not show any consistent spatial pattern, possibly because intensive over-land dispersal homogenized the metacommunity. Thus, although pond connections probably equally promoted dispersal of actively and passively dispersing macroinvertebrates, the implications for the structure of their metacommunities may depend on their dispersal mode. We conclude that dispersal mode has the potential to affect the mechanisms that are integral to metacommunity structure. 相似文献
449.
Dormant propagule banks are important reservoirs of biological and genetic diversity of local communities and populations and provide buffering mechanisms against extinction. Although dormant stages of various plant and animal species are known to remain viable for decades and even centuries, little is known about the effective influence of recolonization from such old sources on the genetic continuity of intermittent populations under natural conditions. Using recent and old dormant eggs recovered from a dated lake sediment core in Kenya, we traced the genetic composition of a local population of the planktonic crustacean Daphnia barbata through a sequence of extinction and recolonization events. This was combined with a phylogeographic and population-genetic survey of regional populations. Four successive populations, fully separated in time, inhabited Lake Naivasha from ca. 1330 to 1570 AD, from ca. 1610 to 1720 AD, from ca. 1840 to 1940 AD, and from 1995 to the present (2001 AD). Our results strongly indicate genetic continuity between the 1840-1940 and 1995-2001 populations, which are separated in time by at least 50 years, and close genetic relatedness of them both to the 1330-1580 population. A software tool (Colonize) was developed to find the most likely source population of the refounded 1995-2001 population and to test the number of colonists involved in the recolonization event. The results confirmed that the 1995-2001 population most probably developed out of a limited number of surviving local dormant eggs from the previous population, rather than out of individuals from regional (central and southern Kenya) or more distant (Ethiopia, Zimbabwe) populations that may have immigrated to Lake Naivasha through passive dispersal. These results emphasize the importance of prolonged dormancy for the natural long-term dynamics of crustacean zooplankton in fluctuating environments and suggest an important role of old local dormant egg banks in aquatic habitat restoration. 相似文献
450.
Testing sustainability by prospective and retrospective demographic analyses: evaluation for palm leaf harvest. 总被引:1,自引:0,他引:1
Harvesting nontimber forest products (NTFPs) is a major economic activity in tropical forests. As many NTFPs are overexploited, sustainability analyses are required to set harvest guidelines. Here we introduce and apply a new approach to evaluating sustainability, which combines prospective (elasticity) and retrospective (Life Table Response Experiments [LTRE]) demographic analyses of matrix population models. We relate the elasticity of vital rates (representing their importance for population growth rate, lamda) to their contribution to harvest-induced change in lamda ("LTRE contribution"). When high-elasticity vital rates have a low LTRE contribution, exploitation is potentially sustainable as negative effects for population growth are buffered. If the reverse is found, there is little scope for sustainability because crucial vital rates are affected. Our approach is less sensitive to chance fluctuations than the commonly used sustainability criterion of lamda = 1.0, as it does not depend on the absolute value of lamda. We applied this analysis to Geonoma deversa, a clustered forest understory palm. We studied three experimentally defoliated and control populations in a Bolivian rainforest during two years. Cutting all leaves of large ramets did not change mortality but strongly affected growth and reproduction. In spite of severe changes in some vital rates, population growth rate was not significantly reduced after defoliation. A literature review revealed that six other understory palms species responded very similarly to defoliation. The combination of LTRE contributions and elasticity analyses showed that low-elasticity vital rates were mainly responsible for the defoliation-induced change in lamda for Geonoma deversa. For two other understory palms (Astrocaryum mexicanum and Chamaedorea radicalis) new demographic analyses yielded very similar results. For Geonoma, the LTRE contribution-elasticity relation strongly changed when we mimicked harvest damage. Adding 5% mortality to defoliated palms caused stronger change in lamda, mainly due to changes in a high-elasticity vital rate (survival). Therefore, harvest practices that involve stem killing are clearly unsustainable. Our results show that commercial leaf cutting in Geonoma deversa is potentially sustainable, and that this is likely the case for understory palms in general. Our approach to evaluating harvest sustainability can be applied to other NTFPs. 相似文献