全文获取类型
收费全文 | 307篇 |
免费 | 2篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 23篇 |
废物处理 | 8篇 |
环保管理 | 46篇 |
综合类 | 58篇 |
基础理论 | 67篇 |
环境理论 | 1篇 |
污染及防治 | 65篇 |
评价与监测 | 14篇 |
社会与环境 | 25篇 |
灾害及防治 | 5篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2017年 | 16篇 |
2016年 | 18篇 |
2015年 | 16篇 |
2014年 | 7篇 |
2013年 | 12篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 10篇 |
2007年 | 20篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1991年 | 4篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1981年 | 2篇 |
1975年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1964年 | 4篇 |
1959年 | 2篇 |
1956年 | 1篇 |
1953年 | 1篇 |
1951年 | 1篇 |
1950年 | 1篇 |
1948年 | 1篇 |
1946年 | 1篇 |
1940年 | 1篇 |
1936年 | 2篇 |
排序方式: 共有312条查询结果,搜索用时 640 毫秒
141.
Burton GA Greenberg MS Rowland CD Irvine CA Lavoie DR Brooker JA Moore L Raymer DF McWilliam RA 《Environmental pollution (Barking, Essex : 1987)》2005,134(1):133-144
An in situ toxicity and bioaccumulation assessment approach is described to assess stressor exposure and effects in surface waters (low and high flow), the sediment-water interface, surficial sediments and pore waters (including groundwater upwellings). This approach can be used for exposing species, representing major functional and taxonomic groups. Pimephales promelas, Daphnia magna, Ceriodaphnia dubia, Hyalella azteca, Hyalella sp., Chironomus tentans, Lumbriculus variegatus, Hydra attenuatta, Hexagenia sp. and Baetis tibialis were successfully used to measure effects on survival, growth, feeding, and/or uptake. Stressors identified included chemical toxicants, suspended solids, photo-induced toxicity, indigenous predators, and flow. Responses varied between laboratory and in situ exposures in many cases and were attributed to differing exposure dynamics and sample-processing artifacts. These in situ exposure approaches provide unique assessment information that is complementary to traditional laboratory-based toxicity and bioaccumulation testing and reduce the uncertainties of extrapolating from the laboratory to field responses. 相似文献
142.
143.
We tested the rarely considered hypothesis that the ultraviolet portion (UVR, 280–400 nm) of the light spectrum affects patterns
of recruitment in reef-building corals. The premise for this hypothesis rests in the fact that biologically relevant intensities
of UVR penetrate to considerable depths (>24 m) in the clear waters surrounding many coral reefs, and that reef organisms
allocate substantial resources to prevent and repair UVR damage. The ability of larvae spawned by the brown morph of the Caribbean
coral, Porites astreoides, to detect and avoid UVR was assessed in petri dishes where one-half of the dish was shielded from UVR and the other exposed.
Observations made every 30 min between 10:30 and 13:30 h showed significantly higher densities of larvae swimming in regions
shielded from UVR. To determine how this behavior affects settlement patterns, larvae collected from P. astreoides adults at 18 m depth were released into chambers deployed at 17 m depth where they were given a choice of three different
light regions in which to settle: PAR (PAR=400–700 nm), PAR+UVAR (UVAR=320–400 nm), and PAR+UVAR+UVBR (UVBR=280–320 nm). At
the end of the experiment, greater numbers of P. astreoides larvae had settled in the region of the tube where UVR was reduced than would be expected if dispersion were random. To our
knowledge, this is the first demonstration in any reef-building coral species that planula larvae can detect UVR and that
it affects their choice of a settlement site. These results indicate that the capacity to detect and avoid habitats with biologically
damaging levels of UVR may be one factor contributing to the successful recruitment of coral larvae. 相似文献
144.
Martin?HeilEmail author Birgit?Baumann Ralf?Krüger K. Eduard?Linsenmair 《Chemoecology》2004,14(1):45-52
Summary. Myrmecophytic plants use obligate ant mutualists as a constitutive
indirect defence mechanism. These plants often produce cellular food bodies (FBs) to
nourish their resident ants. Lipids, proteins, and even highly specialised compounds
such as glycogen have been reported from FBs, but detailed chemical analyses of FB
composition have so far been presented only for Southeast Asian Macaranga
and Central American Piper myrmecophytes. Here we
report the chemical composition of FBs of five myrmecophytic Acacia
(Fabaceae) species from Mexico using HPLC (carbohydrates and proteins) and GC-MS
(lipids). Feeding experiments revealed no hints on any use of external food sources
by the inhabiting Pseudomyrmex ants. These ants
obviously rely completely on FBs and extrafloral nectar provided by their hosts.
The total content of nutrients in Acacia FBs was 15-25% of FB
dry mass, being much lower than in Macaranga or
Piper FBs. Proteins were dominating (8-14 % dm)
in Acacia FBs and thus were present in higher amounts than in
Macaranga FBs, yet in lower amounts than in
Piper. Lipids contributed 1-9 %
of dry mass, showing a lower proportion than in FBs of Macaranga
or Piper. Carbohydrates made up 3-11 % dm, reaching
in most Acacia species the same range as observed in
Macaranga and in Piper FBs.
Water content was 18-24 % of FB fresh mass, and structural tissue obviously made up
a much higher proportion in Acacia FBs than in
Macaranga or Piper
FBs. Both characters might represent an adaptation to producing FBs unprotected at
the leaf tips under dry conditions. Acacia FBs
contain all amino acids and all fatty acids that are considered essential for
insects, and their contents of lipids and proteins are higher than in the leaves
from which they are ontogenetically derived. This indicates a putatively adaptive
enrichment of nutritionally valuable compounds in structures functioning as ant-food. 相似文献
145.
146.
147.
148.
Sarah M. Buckley Ruth H. Thurstan Andrew Tobin John M. Pandolfi 《Conservation biology》2017,31(6):1322-1332
Aggregations of individual animals that form for breeding purposes are a critical ecological process for many species, yet these aggregations are inherently vulnerable to exploitation. Studies of the decline of exploited populations that form breeding aggregations tend to focus on catch rate and thus often overlook reductions in geographic range. We tested the hypothesis that catch rate and site occupancy of exploited fish‐spawning aggregations (FSAs) decline in synchrony over time. We used the Spanish mackerel (Scomberomorus commerson) spawning‐aggregation fishery in the Great Barrier Reef as a case study. Data were compiled from historical newspaper archives, fisher knowledge, and contemporary fishery logbooks to reconstruct catch rates and exploitation trends from the inception of the fishery. Our fine‐scale analysis of catch and effort data spanned 103 years (1911–2013) and revealed a spatial expansion of fishing effort. Effort shifted offshore at a rate of 9.4 nm/decade, and 2.9 newly targeted FSAs were reported/decade. Spatial expansion of effort masked the sequential exploitation, commercial extinction, and loss of 70% of exploited FSAs. After standardizing for improvements in technological innovations, average catch rates declined by 90.5% from 1934 to 2011 (from 119.4 to 11.41 fish/vessel/trip). Mean catch rate of Spanish mackerel and occupancy of exploited mackerel FSAs were not significantly related. Our study revealed a special kind of shifting spatial baseline in which a contraction in exploited FSAs occurred undetected. Knowledge of temporally and spatially explicit information on FSAs can be relevant for the conservation and management of FSA species. 相似文献
149.
Peter J. Edmunds Scott C. Burgess Hollie M. Putnam Marissa L. Baskett Lorenzo Bramanti Nick S. Fabina Xueying Han Michael P. Lesser Joshua S. Madin Christopher B. Wall Denise M. Yost Ruth D. Gates 《Marine Biology》2014,161(12):2719-2734
Many tropical corals have declined in abundance in the last few decades, and evaluating the causal basis of these losses is critical to understanding how coral reefs will change in response to ongoing environmental challenges. Motivated by the likelihood that marine environments will become increasingly unfavorable for coral growth as they warm and become more acidic (i.e., ocean acidification), it is reasonable to evaluate whether specific phenotypic traits of the coral holobiont are associated with ecological success (or failure) under varying environmental conditions including those that are adverse to survival. Initially, we asked whether it was possible to identify corals that are resistant or sensitive to such conditions by compiling quantitative measures of their phenotypic traits determined through empirical studies, but we found only weak phenotypic discrimination between ecological winners and losers, or among taxa. To reconcile this outcome with ecological evidence demonstrating that coral taxa are functionally unequal, we looked beyond the notion that phenotypic homogeneity arose through limitations of empirical data. Instead, we examined the validity of contemporary means of categorizing corals based on ecological success. As an alternative means to distinguish among functional groups of corals, we present a demographic approach using integral projection models (IPMs) that link organismal performance to demographic outcomes, such as the rates of population growth and responses to environmental stress. We describe how IPMs can be applied to corals so that future research can evaluate within a quantitative framework the extent to which changes in physiological performance influence the demographic underpinnings of ecological performance. 相似文献
150.