全文获取类型
收费全文 | 552篇 |
免费 | 26篇 |
国内免费 | 7篇 |
专业分类
安全科学 | 15篇 |
废物处理 | 18篇 |
环保管理 | 125篇 |
综合类 | 49篇 |
基础理论 | 160篇 |
环境理论 | 1篇 |
污染及防治 | 166篇 |
评价与监测 | 32篇 |
社会与环境 | 14篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 7篇 |
2022年 | 6篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 18篇 |
2016年 | 11篇 |
2015年 | 14篇 |
2014年 | 11篇 |
2013年 | 43篇 |
2012年 | 18篇 |
2011年 | 21篇 |
2010年 | 20篇 |
2009年 | 16篇 |
2008年 | 23篇 |
2007年 | 33篇 |
2006年 | 39篇 |
2005年 | 14篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 12篇 |
1998年 | 8篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1974年 | 5篇 |
1969年 | 3篇 |
1954年 | 2篇 |
排序方式: 共有585条查询结果,搜索用时 15 毫秒
151.
152.
Scot D. Anderson Taylor K. Chapple Salvador J. Jorgensen A. Peter Klimley Barbara A. Block 《Marine Biology》2011,158(6):1233-1237
Mark-recapture techniques can be used to estimate white shark (Carcharodon carcharias) population abundance. These frameworks are based on assumptions that marks are conserved and animals are present at the
sampling location over the entire duration of the study. Though these assumptions have been validated across short-time scales
for white sharks, long-term studies of population trends are dependent on these assumptions being valid across longer periods.
We use 22 years of photographic data from aggregation sites in central California to support the use of dorsal fin morphology
as long-term individual identifiers. We identified five individuals over 16–22 years, which support the use of dorsal fins
as long-time individual identifiers, illustrate strong yearly site fidelity to coastal aggregation sites across extended time
periods (decades), and provide the first empirical validation of white shark longevity >22 years. These findings support the
use of fin morphology in mark-recapture frameworks for white sharks. 相似文献
153.
Joshua A. Vance Norse B. Angus James T. Anderson 《Environmental monitoring and assessment》2013,185(9):7739-7748
Construction of man-made objects such as roads and bridges may have impacts on wildlife depending on species or location. We investigated songbirds and small mammals along the Ohio River, WV, USA at a new bridge both before and after construction and at a bridge crossing that was present throughout the study. Comparisons were made at each site over three time periods (1985–1987 [Phase I] and 1998–2000 [Phase II] [pre-construction], 2007–2009 [Phase III] [post-construction]) and at three distances (0, 100, 300 m) from the bridge or proposed bridge location. Overall, 70 songbirds and 10 small mammals were detected during the study. Cliff swallows (Petrochelidon pyrrhonota) and rock pigeons (Columba livia) showed high affinity for bridges (P?<?0.05). Combined small mammal abundances increased between Phases I and II (P?<?0.05), but did not differ between Phases II and III (P?>?0.05). Species richness and diversity for songbirds and small mammals did not differ before and after bridge construction (P?>?0.05). We found that most species sampled did not respond to the bridge crossing, and believe that the bridge is not causing any measurable negative density impacts to the species we investigated. The new bridge does provide habitat for exotic rock pigeons that are adjusted to man-made structures for nesting. 相似文献
154.
Anderson Martins de Souza Braz Antonio Rodrigues Fernandes José Roberto Ferreira Luís Reynaldo Ferracciú Alleoni 《Environmental science and pollution research international》2013,20(10):7231-7242
The solid-solution distribution or partition coefficient (Kd) is a measure of affinity of potentially toxic elements (PTE) for soil colloids. Kd plays a key role in several models for defining PTE guideline values in soils and for assessing environmental risks, and its value depends on edaphic and climatic conditions of the sites where the soils occur. This study quantified Kd values for Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn from representative soil samples from Brazil’s eastern Amazon region, which measures 1.2 million km2. The Kd values obtained were lower than those set by both international and Brazilian environmental agencies and were correlated with the pH, Fe and Mn oxide content, and cationic exchange capacity of the soils. The following order of decreasing affinity was observed: Pb?>?Cu?>?Hg?>?Cr?>?Cd?≈?Co?>?Ni?>?Zn. 相似文献
155.
Bruce J. Eckholm Kirk E. Anderson Milagra Weiss Gloria DeGrandi-Hoffman 《Behavioral ecology and sociobiology》2011,65(5):1037-1044
Multiple mating by honeybee queens results in colonies of genotypically diverse workers. Recent studies have demonstrated
that increased genetic diversity within a honeybee colony increases the variation in the frequency of tasks performed by workers.
We show that genotypically diverse colonies, each composed of 20 subfamilies, collect more pollen than do genotypically similar
colonies, each composed of a single subfamily. However, genotypically similar colonies collect greater varieties of pollen
than do genotypically diverse colonies. Further, the composition of collected pollen types is less similar among genotypically
similar colonies than among genotypically diverse colonies. The response threshold model predicts that genotypic subsets of
workers vary in their response to task stimuli. Consistent with this model, our findings suggest that genotypically diverse
colonies likely send out fewer numbers of foragers that independently search for pollen sources (scouts) in response to protein
demand by the colony, resulting in a lower variety of collected pollen types. The cooperative foraging strategy of honeybees
involves a limited number of scouts monitoring the environment that then guide the majority of foragers to high quality food
sources. The genetic composition of the colony appears to play an important role in the efficiency of this behavior. 相似文献
156.
多溴联苯醚(Polybrominated diphenyl ethers, PBDEs)为一类新型的溴代阻燃剂,广泛应用于塑料制品、纺织品、电路板和建筑材料等领域。随着生产量和使用量的增加,PBDEs已造成全球环境污染,其带来的环境问题已引起各国关注。同时PBDEs的长距离迁移性和难降解性,使其在环境介质中进行富集,从而加重污染。归纳了中国地区PBDEs的监测进展,分别从大气、水体、沉积物和土壤中PBDEs的污染水平以及原因进行了分析和探讨。在此基础上,对于我国PBDEs的研究方向提出了展望。 相似文献
157.
The increasing use of ozone in water disinfection processes has been the focus of considerable concern in regards to inorganic disinfection by product formation of bromate in waters containing bromide. Due to the public health risk caused by the presence of bromate as a suspected carcinogen, attention had been addressed to the conditions under which bromate is formed. In this study, photoanodic bromine generation and bromate (BrO(3)(-)) formation were investigated using a TiO(2) electrode in a photoelectrocatalytic (PEC) treatment process. The separation of anodic and cathodic reactions in the PEC system resulted in a pH decrease from 9.3 to 3.0 in the photoanode compartment and an increase to 11.0 in the cathode compartment. Under a photo-illumination intensity of 5.7 m W cm(-2) UV, a biasing potential of +1.0V vs SCE, a pH of 6.0 and at a NaBr concentration of 1.0 x 10(-2) M, active bromine formation increased over time with 2.4 x 10(-6) M min(-6) rate and reached a steady-state concentration of 1.44 x 10(-4) M in 60 min. Bromate formation was detected after a lag-period of 15 min and exhibited a continuous increasing trend with respect to irradiation time. No bromate formation was observed below pH 6.5 whereas an increasing bromate concentrations and pH up to pH=8.5 were noted. 相似文献
158.
159.
160.