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471.
危险化学品运输路径优化选择模型研究 总被引:1,自引:0,他引:1
针对危险化学品运输的路径优化选择问题,将多目标格序决策理论引入到路径方案评价比选中,结合指标选取的综合性和可操作性原则,从6个方面构建危险化学品运输路径比选指标体系:影响区域水源保护性(p1)、影响区域途径区域名胜古迹保护性(p2)、影响区域生态环境保护性(p3)、影响区域人口规模(p4)、影响区域厂矿规模(p5)、运输路径综合运输效益(p6)。通过对各方案综合差异度的计算,实现了备选方案的格序化排序。此外在模型体系权重计算中采用了熵值法,实现了权重确定的客观性。最后,应用该模型结合算例对该模型进行了试算,证明了模型的合理性。 相似文献
472.
Alex Potapov Jim R. Muirhead Subhash R. Lele Mark A. Lewis 《Ecological modelling》2011,222(4):964-972
Freshwater aquatic systems in North America are being invaded by many different species, ranging from fish, mollusks, cladocerans to various bacteria and viruses. These invasions have serious ecological and economic impacts. Human activities such as recreational boating are an important pathway for dispersal. Gravity models are used to quantify the dispersal effect of human activity. Gravity models currently used in ecology are deterministic. This paper proposes the use of stochastic gravity models in ecology, which provides new capabilities both in model building and in potential model applications. These models allow us to use standard statistical inference tools such as maximum likelihood estimation and model selection based on information criteria. To facilitate prediction, we use only those covariates that are easily available from common data sources and can be forecasted in future. This is important for forecasting the spread of invasive species in geographical and temporal domain. The proposed model is portable, that is it can be used for estimating relative boater traffic and hence relative propagule pressure for the lakes not covered by current boater surveys. This makes our results broadly applicable to various invasion prediction and management models. 相似文献
473.
474.
随着核工业的发展,含铀放射性废水的产生量越来越大,必须进行妥善处理与处置.微藻吸附技术是近年来放射性废水处理领域的研究热点,而获得吸附铀的优势藻种则是该技术得以研究和应用的基础.从工程应用的角度出发确定了筛选原则,并针对11株备选藻种进行了优势藻种筛选工作.栅藻LX1对铀的吸附容量最大,为40.7 mg·g~(-1);在m BG11培养基(模拟城镇污水处理厂污染物排放一级A标准的氮磷浓度限值)中的生物质产量较高,为0.32 g·L~(-1);生长进入稳定期后的沉降性能较好,沉降率为45.3%.综上,在本研究范围内,栅藻LX1为放射性废水处理中吸附铀的优势藻种. 相似文献
475.
In anarchistic honey-bee colonies, many workers’ sons are reared despite the presence of the queen. Worker-laid eggs are normally
eaten by other workers in queenright colonies. Workers are thought to discriminate between queen-laid and worker-laid eggs
by the presence or absence of a queen-produced egg-marking pheromone. This study compared the survival of three classes of
eggs (worker-laid eggs from anarchistic colonies, worker-laid eggs from non-anarchistic queenless colonies, and queen-laid
eggs) in both queenright normal colonies and queenright anarchistic colonies, in order to test the hypothesis that anarchistic
workers evade policing by laying more acceptable eggs. As expected, few worker-laid eggs from non-anarchistic colonies survived
more than 2 h. In contrast, worker-laid eggs from anarchistic colonies had much greater acceptability, which in some trials
equalled the acceptability of queen-laid eggs. Anarchistic colonies were generally less discriminatory than normal queenright
colonies towards worker-laid eggs, whether these originated from anarchistic colonies or normal queenless colonies. This indicates
that the egg-removal aspect of the anarchistic syndrome involves both worker laying of eggs with greater acceptability and
reduced discriminatory behaviour of policing workers.
Received: 19 July 1999 / Received in revised form: 3 November 1999 / Accepted: 20 November 1999 相似文献
476.
477.
HERBERT TUSHABE§§§ JAMES KALEMA ACHILLES BYARUHANGA† JOSEPHINE ASASIRA PAUL SSEGAWA REW BALMFORD‡ TIM DAVENPORT§ JON FJELDSÅ IB FRIIS†† DEBORAH PAIN DEREK POMEROY PAUL WILLIAMS§§ CHARLES WILLIAMS‡ 《Conservation biology》2006,20(1):85-99
Abstract: BirdLife International's Important Bird Areas (IBA) program is the most developed global system for identifying sites of conservation priority. There have been few assessments, however, of the conservation value of IBAs for nonavian taxa. We combined past data with extensive new survey results for Uganda's IBAs in the most comprehensive assessment to date of the wider biodiversity value of a tropical country's IBA network. The combined data set included more than 35,000 site × species records for birds, butterflies, and woody plants at 86 Ugandan sites (23,400 km2 ), including 29 of the country's 30 IBAs, with data on additional taxa for many sites. Uganda's IBAs contained at least 70% of the country's butterfly and woody plant species, 86% of its dragonflies and 97% of its birds. They also included 21 of Uganda's 22 major vegetation types. For butterflies, dragonflies, and some families of plants assessed, species of high conservation concern were well represented (less so for the latter). The IBAs successfully represented wider biodiversity largely because many have distinctive avifaunas and, as shown by high cross-taxon congruence in complementarity, such sites tended to be distinctive for other groups too. Cross-taxon congruence in overall species richness was weaker and mainly associated with differences in site size. When compared with alternative sets of sites selected using complementarity-based, area-based, or random site-selection algorithms, the IBA network was efficient in terms of the number of sites required to represent species but inefficient in terms of total area. This was mainly because IBA selection considers factors other than area, however, which probably improves both the cost-effectiveness of the network and the persistence of represented species. 相似文献
478.
环境管理政策的选择是一项复杂的决策过程 ,本文拟就环境管理政策的一般原理和基本过程进行阐述。一是对环境政策、环境管理政策的选择空间进行界定 ,对环境管理政策的选择进行分析 ;二是提出环境管理政策的选择原理和评判准则 ;三是对环境管理政策选择的可操作过程进行分析和论述。并由此得出 :环境管理政策的选择应在考虑具体的外部因素以及内部因素的基础上的政策择优 ,有效的环境管理政策的选择应该是给定约束条件下的管制手段、经济手段和劝说手段的恰当组合。 相似文献
479.
Peter M. Kappeler 《Behavioral ecology and sociobiology》1997,41(2):115-127
The primates of Madagascar (Lemuriformes) deviate from fundamental predictions of sexual selection theory in that polygynous
species lack sexual dimorphism, have even adult sex ratios and often live in female-dominated societies. It has been hypothesized
that intrasexual selection in these species is either reduced or primarily focused on traits related to scramble competition.
The goal of this study was to examine these hypotheses by studying the mating system of a solitary nocturnal species, Mirzacoquereli. During a 4-year field study in western Madagascar, I captured and followed 88 individually marked animals. I found that
adult males were significantly larger than females, providing the first evidence for sexual size dimorphism in lemurs. In
addition, the adult sex ratio was biased in favour of females in 3 out of 4 years. There was no significant sex difference
in canine size, however. Males showed pronounced seasonal variation in testis size with a 5-fold increase before and during
the short annual mating season. During the mating season, males had more injuries than females and more than quadrupled their
home ranges, overlapping with those of more than ten females, but also with about the same number of rivals. Only about one
social interaction per 10 h of observation was recorded, but none of them were matings. Together, these results indicate that
these solitary lemurs are clearly subject to intrasexual selection and that male-male competition is primarily, but not exclusively,
of the scramble type. In addition, they suggest that the above-mentioned idiosyncracies may be limited to group-living lemurs,
that social systems of solitary primates are more diverse than previously thought, and that the temporal distribution of receptive
females is responsible for this particular male mating strategy.
Received: 11 January 1997 / Accepted after revision: 18 April 1997 相似文献
480.
Corey R. Freeman-Gallant 《Behavioral ecology and sociobiology》1997,40(6):395-400
Empirical relationships between parentage and male parental care are commonly interpreted in the context of life-history
models that consider increased offspring survivorship as the only benefit of paternal effort. However, indirect benefits associated
with male care can also influence a male's response to cuckoldry: if females allocate paternity according to their prior experience
with male parental care, it may pay for males to provision extra-pair young in early broods. Here, I assess the relationship
between first-brood parentage and paternal care in a population of Savannah sparrows (Passerculussandwichensis) where a male's fertilization success in the second brood appears to be influenced by his prior parental performance. Based
on the multi-locus DNA fingerprinting of 17 first broods, male feeding effort was influenced by parentage (percent of brood
resulting from within-pair fertilizations) but not by brood size, male mating status (monogamous versus polygynous), timing
of breeding (hatching date), structural size (wing length) or condition (mass). Males provided more care to broods that contained
few within-pair young. This result supports the idea that males provision young to increase their future mating success, but
alternative hypotheses involving male quality and timing of breeding cannot be excluded.
Received: 13 August 1996 / Accepted after revision: 22 February 1997 相似文献