全文获取类型
收费全文 | 2355篇 |
免费 | 48篇 |
国内免费 | 27篇 |
专业分类
安全科学 | 98篇 |
废物处理 | 94篇 |
环保管理 | 721篇 |
综合类 | 146篇 |
基础理论 | 504篇 |
环境理论 | 1篇 |
污染及防治 | 612篇 |
评价与监测 | 160篇 |
社会与环境 | 74篇 |
灾害及防治 | 20篇 |
出版年
2023年 | 14篇 |
2022年 | 24篇 |
2021年 | 22篇 |
2020年 | 25篇 |
2019年 | 25篇 |
2018年 | 32篇 |
2017年 | 34篇 |
2016年 | 49篇 |
2015年 | 40篇 |
2014年 | 40篇 |
2013年 | 307篇 |
2012年 | 76篇 |
2011年 | 94篇 |
2010年 | 92篇 |
2009年 | 64篇 |
2008年 | 103篇 |
2007年 | 105篇 |
2006年 | 116篇 |
2005年 | 95篇 |
2004年 | 65篇 |
2003年 | 95篇 |
2002年 | 85篇 |
2001年 | 26篇 |
2000年 | 38篇 |
1999年 | 27篇 |
1998年 | 44篇 |
1997年 | 33篇 |
1996年 | 32篇 |
1995年 | 31篇 |
1994年 | 26篇 |
1993年 | 22篇 |
1992年 | 27篇 |
1991年 | 24篇 |
1990年 | 26篇 |
1989年 | 23篇 |
1988年 | 28篇 |
1987年 | 20篇 |
1986年 | 22篇 |
1985年 | 26篇 |
1984年 | 42篇 |
1983年 | 32篇 |
1982年 | 36篇 |
1981年 | 38篇 |
1980年 | 26篇 |
1979年 | 42篇 |
1978年 | 29篇 |
1977年 | 23篇 |
1976年 | 21篇 |
1971年 | 12篇 |
1970年 | 9篇 |
排序方式: 共有2430条查询结果,搜索用时 399 毫秒
461.
Anthony J. Gaston Paul A. Smith Laura McFarlane Tranquilla William A. Montevecchi David A. Fifield H. Grant Gilchrist April Hedd Mark L. Mallory Gregory J. Robertson Richard A. Phillips 《Marine Biology》2011,158(9):1929-1941
The non-breeding movements of marine birds were poorly known until recently, but this information is essential to understanding
the risk to different geographical populations from events on the wintering grounds. We tracked the migration routes and wintering
areas of Thick-billed Murre Uria lomvia from two breeding colonies in eastern Canada: Coats Island in northern Hudson Bay and The Minarets, Baffin Island, during
the period August 2007–May 2008 using geolocation loggers. Birds from The Minarets moved south rapidly post-breeding and wintered
principally off Newfoundland and southern Labrador, or between Newfoundland and southern Greenland, remaining south of 55°N
until at least the spring equinox. Those from Coats Island remained in Hudson Bay until at least mid-November, after which
they moved rapidly through Hudson Strait to winter in southern Davis Strait and the northern Labrador Sea, mostly north of
55°N. Many individuals stayed throughout the winter in areas of heavy ice cover. Adults from the two colonies appear to be
completely segregated in winter and those from Coats Island probably did not enter the area of the winter hunt in Newfoundland.
Unexpectedly, some birds from The Minarets wintered in waters beyond the continental slope and outside the distribution of
pack ice, demonstrating that particular individuals can be wholly pelagic throughout the winter. Coats Island birds returned
through Hudson Strait as soon as open water areas became available in spring. Their sojourn in Hudson Bay coincided very closely
with the occurrence of areas with <90% ice cover. In spite of the relatively large error in positions obtained from geolocation
loggers, our results demonstrated the value of these devices by uncovering a number of previously unknown aspects of Thick-billed
Murre non-breeding ecology in the Northwest Atlantic. Comparison of the non-breeding ecology based on SST experienced in winter
show that the winter niche is broader than hitherto assumed, demonstrating that separate populations may experience different
selection in the face of climate change. 相似文献
462.
William J.M. Probert Martin DrechslerPeter W.J. Baxter Hugh P. Possingham 《Ecological modelling》2011,222(10):1781-1789
It is becoming increasingly popular to consider species interactions when managing ecological foodwebs. Such an approach is useful in determining how management can affect multiple species, with either beneficial or detrimental consequences. Identifying such actions is particularly valuable in the context of conservation decision making as funding is severely limited. This paper outlines a new approach that simplifies the resource allocation problem in a two species system for a range of species interactions: independent, mutualism, predator-prey, and competitive exclusion. We assume that both species are endangered and we do not account for decisions over time. We find that optimal funding allocation is to the conservation of the species with the highest marginal gain in expected probability of survival and that, across all except mutualist interaction types, optimal conservation funding allocation differs between species. Loss in efficiency from ignoring species interactions was most severe in predator-prey systems. The funding problem we address, where an ecosystem includes multiple threatened species, will only become more commonplace as increasing numbers of species worldwide become threatened. 相似文献
463.
Oliver Manlik Robert C. Lacy William B. Sherwin Hugh Finn Neil R. Loneragan Simon J. Allen 《Conservation biology》2022,36(4):e13897
Human-caused mortality of wildlife is a pervasive threat to biodiversity. Assessing the population-level impact of fisheries bycatch and other human-caused mortality of wildlife has typically relied upon deterministic methods. However, population declines are often accelerated by stochastic factors that are not accounted for in such conventional methods. Building on the widely applied potential biological removal (PBR) equation, we devised a new population modeling approach for estimating sustainable limits to human-caused mortality and applied it in a case study of bottlenose dolphins affected by capture in an Australian demersal otter trawl fishery. Our approach, termed sustainable anthropogenic mortality in stochastic environments (SAMSE), incorporates environmental and demographic stochasticity, including the dependency of offspring on their mothers. The SAMSE limit is the maximum number of individuals that can be removed without causing negative stochastic population growth. We calculated a PBR of 16.2 dolphins per year based on the best abundance estimate available. In contrast, the SAMSE model indicated that only 2.3–8.0 dolphins could be removed annually without causing a population decline in a stochastic environment. These results suggest that reported bycatch rates are unsustainable in the long term, unless reproductive rates are consistently higher than average. The difference between the deterministic PBR calculation and the SAMSE limits showed that deterministic approaches may underestimate the true impact of human-caused mortality of wildlife. This highlights the importance of integrating stochasticity when evaluating the impact of bycatch or other human-caused mortality on wildlife, such as hunting, lethal control measures, and wind turbine collisions. Although population viability analysis (PVA) has been used to evaluate the impact of human-caused mortality, SAMSE represents a novel PVA framework that incorporates stochasticity for estimating acceptable levels of human-caused mortality. It offers a broadly applicable, stochastic addition to the demographic toolbox to evaluate the impact of human-caused mortality on wildlife. 相似文献
464.
The foraging behaviours and dietary compositions of three co-occurring labrids (Ophthalmolepis lineolatus, Notolabrus gymnogenis and Pictilabrus laticlavius), which are conspicuous on rocky reefs in temperate south-eastern Australia, were investigated between 2003 and 2005. SCUBA
observations at two locations showed that the feeding intensity, and hence the associated effects of these fishes on rocky
reef invertebrate prey, was temporally consistent. Relative differences in the contributions of ingested prey and use of different
feeding microhabitats demonstrated that the feeding ecology differed significantly among the three species. Thus, O. lineolatus fed on proportionately higher volumes of polychaetes, polyplacophorans, marginellid gastropods (especially Austroginella sp.), bivalves and echinoids, which were sighted opportunistically in a wide selection of microhabitats, but particularly
in sand/rubble. Ambush hunting was used regularly by smaller N. gymnogenis and all sizes of P. laticlavius to forage on amphipods, small decapods and small gastropods at algal bases or fronds and Diopatra dentata tubes. Amphipods were similarly important in the diet of smaller O. lineolatus. Larger N. gymnogenis foraged opportunistically over an increased reef area and made greater use of microhabitats that offered minimal prey refuge
(e.g. sand/rubble, bare rock/steel) from which common prey, in particular decapods, were obtained. The significant intra-
and inter-specific differences in dietary compositions, allied with differences in the use of feeding microhabitats, would
facilitate co-occurrence of these three conspicuous species and contribute to maintaining high richness of labrid species
in reef systems. Echinoids were regularly consumed by each species but they made a moderate contribution to the diet of only
O. lineolatus, which suggests that only one of the three labrids is likely to play a significant role in regulation of echinoid densities
in these rocky reef habitats. However, the broad diets and diverse forging strategies employed by these labrid species imply
that they have a system-wide influence on invertebrate prey on rocky reefs. 相似文献
465.
Andrea L. Jaeger Miehls Doran M. Mason Kenneth A. Frank Ann E. Krause Scott D. Peacor William W. Taylor 《Ecological modelling》2009,220(22):3194
Exotic species invasion is widely considered to affect ecosystem structure and function. Yet, few contemporary approaches can assess the effects of exotic species invasion at such an inclusive level. Our research presents one of the first attempts to examine the effects of an exotic species at the ecosystem level in a quantifiable manner. We used ecological network analysis (ENA) and a social network analysis (SNA) method called cohesion analysis to examine the effect of zebra mussel (Dreissena polymorpha) invasion on the Oneida Lake, New York, USA, food web. We used ENA to quantify ecosystem function through an analysis of food web carbon transfer that explicitly incorporated flow over all food web paths (direct and indirect). The cohesion analysis assessed ecosystem structure through an organization of food web members into subgroups of strongly interacting predators and prey. Our analysis detected effects of zebra mussel invasion throughout the entire Oneida Lake food web, including changes in trophic flow efficiency (i.e., carbon flow among trophic levels) and alterations of food web organization (i.e., paths of carbon flow) and ecosystem activity (i.e., total carbon flow). ENA indicated that zebra mussels altered food web function by shunting carbon from pelagic to benthic pathways, increasing dissipative flow loss, and decreasing ecosystem activity. SNA revealed the strength of zebra mussel perturbation as evidenced by a reorganization of food web subgroup structure, with a decrease in importance of pelagic pathways, a concomitant rise of benthic pathways, and a reorganization of interactions between top predator fish. Together, these analyses allowed for a holistic understanding of the effects of zebra mussel invasion on the Oneida Lake food web. 相似文献
466.
William E. CooperJr. 《Behavioral ecology and sociobiology》2009,63(12):1765-1771
Flight initiation distance, the predator–prey distance when escape begins, is predicted by escape theory to decrease if fleeing
entails loss of benefits. Shortening of flight initiation distance during social interactions is known only in males and only
in a few species. In a previous study, male, but not female, Sceloporus virgatus lizards had shorter flight initiation distance when interacting with tethered conspecifics. Females in that study were not
gravid or close to ovulating. I predicted that flight initiation distance would be shorter in gravid females that perform
sidle-hopping displays to reject courtship than in lone females. I tested this prediction and examined effects of social interactions
by males with free-ranging conspecifics to ensure that previous findings were not artifacts of tethering and experimental
introduction of conspecifics. Flight initiation distance was shorter in females when interacting with males than when alone;
it was also shorter in males interacting with either sex. Thus, when beneficial for reproductive reasons, social interaction
affects flight initiation distance in females, but at other times, it does not. Lesser shortening of flight initiation distance
in females than males may be a consequence of greater social benefit to males and protection of reproductive investment by
females. 相似文献
467.
Villy Christensen Carl J. Walters Robert Ahrens Jacqueline Alder Joe Buszowski Line Bang Christensen William W.L. Cheung John Dunne Rainer Froese Vasiliki Karpouzi Kristin Kaschner Kelly Kearney Sherman Lai Vicki Lam Maria L.D. Palomares Aja Peters-Mason Chiara Piroddi Jorge L. Sarmiento Jeroen Steenbeek Rashid Sumaila Reg Watson Dirk Zeller Daniel Pauly 《Ecological modelling》2009
We present a new methodology for database-driven ecosystem model generation and apply the methodology to the world's 66 currently defined Large Marine Ecosystems. The method relies on a large number of spatial and temporal databases, including FishBase, SeaLifeBase, as well as several other databases developed notably as part of the Sea Around Us project. The models are formulated using the freely available Ecopath with Ecosim (EwE) modeling approach and software. We tune the models by fitting to available time series data, but recognize that the models represent only a first-generation of database-driven ecosystem models. We use the models to obtain a first estimate of fish biomass in the world's LMEs. The biggest hurdles at present to further model development and validation are insufficient time series trend information, and data on spatial fishing effort. 相似文献
468.
469.
中国特色的城市化问题 总被引:16,自引:3,他引:13
针对当前社会经济发展中有中国特色的城市化建设问题,展开全方位、多视角的分析阐述,指出了认识对城市化问题的种种误区。提出中国的城市化发展应该与国情国力、工业化发展形势相协调,过程应有序、健康。并认为:(1)在相当长一段时间内、中国城市化水平以界定在50%-55%为宜,而不应该盲目追求西方国家不同国情的高指标、高比例;(2)对城市今后的发展规模应有稳步发展;(4)乡村城镇化必须发展生态农业与生态工业、走集约化、专业化的道路。正确引导中国的城市化进程,把城市发展和农村、工业和农业、人口流动、产业政策、区域平衡、科技进步、外向型经济可持续发展等当作整体一盘棋来统筹制定总体战略。 相似文献
470.
From September through November 1994, the U.S. Environmental Protection Agency (EPA) conducted a field demonstration of the remediation of highly contaminated groundwater at the Nascolite Superfund site located in Millville, New Jersey. Besides high concentrations of the major contaminant, methyl methacrylate (MMA), the groundwater also contained small amounts of volatile and semivolatile organic compounds. ZenoGem® technology, an integrated bioreactor and ultrafiltration membrane system, was employed for this demonstration project. Approximately 30,000 gallons of groundwater containing MMA in concentrations of 567 to 9,500 milligrams per liter (mg/L) and chemical oxygen demand (COD) values ranging from 1,490 to 19,600 mg/L was treated. The demonstration focused on the system's ability to remove MMA and reduce COD from the groundwater. Results of the three‐month demonstration showed that average MMA and COD removal efficiencies were greater than 99.9 and 86.9, respectively. The total cost of treatment, depending on the duration of the project, is estimated to vary from $0.22 to $0.55 (in 1994 dollars) per gallon of groundwater treated. © 2001 John Wiley & Sons. 相似文献