全文获取类型
收费全文 | 371篇 |
免费 | 2篇 |
国内免费 | 21篇 |
专业分类
安全科学 | 5篇 |
废物处理 | 17篇 |
环保管理 | 67篇 |
综合类 | 60篇 |
基础理论 | 97篇 |
环境理论 | 1篇 |
污染及防治 | 101篇 |
评价与监测 | 8篇 |
社会与环境 | 19篇 |
灾害及防治 | 19篇 |
出版年
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 11篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 19篇 |
2013年 | 34篇 |
2012年 | 16篇 |
2011年 | 40篇 |
2010年 | 20篇 |
2009年 | 50篇 |
2008年 | 30篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有394条查询结果,搜索用时 338 毫秒
171.
172.
During 2006-2008, a monitoring program was conducted on 29 target compounds, including PCDD/Fs and dl-PCBs, comprising 150 randomly collected individual food samples marketed in the Region of Valencia, Spain, grouped into 8 categories (vegetables, cereals, fats and oils, eggs, milk and dairy products, fish products, meat and meat products and fish oil). For PCDD/Fs, the highest frequency of detection corresponds to 1,2,3,4,6,7,8-HpCDD, OCDD, 2,3,4,7,8-PeCDF; and PCBs 118, 105 and 156 were the more frequent dl-PCBs. The food groups presenting higher contamination, expressed as toxic equivalents (WHO-TEQs), were fish oil (6.38 pg WHO-TEQ g−1 fat), fish (1.21 pg WHO-TEQ g−1 w.w.) and milk and dairy products (0.90 pg WHO-TEQ g−1 fat). Of all analysed samples, only two fish oils presented levels higher than the EU limits for total WHO-TEQ. The average PCDD/Fs and dl-PCBs intakes were estimated as 2.86 pg WHO-TEQ kg−1 b.w. d−1 and 4.58 pg WHO-TEQ kg−1 b.w. d−1, for adults and children, respectively, using the deterministic method for chronic exposure. The main contributors to total intake for adults were fish (59%), milk and dairy products (19%), and fat and oils (9%). The average daily intake for adults (2.86 pg WHO-TEQ kg−1 b.w. d−1) is within range of TDI recommended by the WHO (1-4 pg WHO-TEQ kg−1 b.w. d−1), and slightly above the TWI and PTMI adopted by SCF and JECFA respectively. 相似文献
173.
This paper quantifies food loss rates for fruit & vegetables, dairy products and bread & pastry as well as donations to social services. In addition potential influencing factors and reasons for food losses are investigated in order to provide a basis for the development of waste prevention measures. Detailed data from 612 retail outlets all over Austria, which covered the period of one year, were analysed and sorting analyses of discarded food were carried out in a small sample of retail outlets. Food loss amounts to 1.3% of the sales of dairy products, 2.8% for bread & pastry and 4.2% for fruit & vegetables. Returned bread amounts to additional 9.7% of the sales of bread & pastry. The food loss rates are similar to the results of previous publications. At present, 7% of the food loss is donated to social services, 38% of retail outlets do not donate any articles at all. Food loss rates are declining with increasing sales areas, increasing numbers of purchases per year and increasing sales of the retail outlet, but explain only 33% or less of the variation of food loss rates. Large differences between retail outlets of comparable structure indicate potential for reduction. More than a quarter of discarded food articles did not show any flaws besides the expiration of the best before or sell-by date. Waste prevention approaches should focus on avoiding returns, transfer of best practices, information and education of employees and customers as well as strengthening the donation to social services. 相似文献
174.
Consumer's choice of food can influence the environment. In Sweden, in common with many other countries, consumers need to be given information so they can make environmentally informed shopping choices. However, what is the most advantageous dietary choice to lower greenhouse emissions? This study investigates the greenhouse gas emissions associated with food production for food consumed in Sweden annually. Specifically, this study compares greenhouse gas emissions associated with a nutritionally and environmentally sustainable diet with the average consumption of food in Sweden 1999. The study concludes that the change in energy use and greenhouse gas emission associated with this change of diet is negligible. Lowering greenhouse gas emissions by changing food production processes results in more profound changes than teaching consumers to make environmentally correct choices. There is a basic need for a reduction or a replacement of the use of fossil fuels to produce and distribute our food in order to reach any significant reduction in the emission of greenhouse gases. Swedish agricultural policy does not provide ways to reduce greenhouse gas emissions. In Sweden therefore there is an immediate need to design policy instruments with the primary aim of reducing the greenhouse effect. 相似文献
175.
Helen Young 《Disasters》1987,11(2):102-109
A survey of thirty-four feeding programmes in Ethiopia and East Sudan was undertaken. Wie differences were found between the two countries and also within Ethiopia. Irrelugar general ration distribution was commonplace in Ethiopia, thus placing an extra strain on selective feeding programmes. The principal admission criteria to Selected Feeding Programmes (SFPs) were weight for height categories. The cut-off stages of the emergency. Useful compasirions between programmes were hampered by such differences, as well as by the different methods of reporting data.
The types of food usd in programmes depended on availability and included high energyu drinks, poridges, take-home pre-mixes and sometimes indigenous foods. A large number of foods e.g. cornedbedef, chicken paté, noodles, da4tes etc. Some added interesting variety and added nutritional value to the diet, while others caused more problems than they solved due to their low acceptability, inappropriate packaging, limited accompanying information and complex an costly preparation. The imlementation of food dination policies by donors and consignees regarding appropriate foodstuffs and their recommended use was considered to be the major solution to this problem. 相似文献
The types of food usd in programmes depended on availability and included high energyu drinks, poridges, take-home pre-mixes and sometimes indigenous foods. A large number of foods e.g. cornedbedef, chicken paté, noodles, da4tes etc. Some added interesting variety and added nutritional value to the diet, while others caused more problems than they solved due to their low acceptability, inappropriate packaging, limited accompanying information and complex an costly preparation. The imlementation of food dination policies by donors and consignees regarding appropriate foodstuffs and their recommended use was considered to be the major solution to this problem. 相似文献
176.
Bob Baulch 《Disasters》1987,11(3):195-204
The traglic recent events in Ethiopia and other parts of Africa have again foccussed attention on the different anaytical approaches to the problems iof famine. Perhaps the most important analytical contribution to this field has been Sen's "entitlements approach." One of the case studies Sen used to articulate this approach was of the 1972–1973 famine in Wollo Province, Ethiopia. This article provides a provisional assessment of the famine process in the Wollo during 1982–1985 to set against the analysis by Sen of the earlier famine. Some striking contrasts are revealed. 相似文献
177.
Barbara Raffaelli Eija Leppälä Clément Chappuis Kristiina Wähälä 《Environmental Chemistry Letters》2006,4(1):1-9
Seven new dibenzylbutyrolactone and six new dibenzylbutanediol lignans were prepared to assist in the identification of a
number of potential mammalian metabolites of the endocrine disrupting plant lignans syringaresinol and medioresinol, present
in food. 相似文献
178.
Patrice Lucchetta Emmanuel Desouhant Eric Wajnberg Carlos Bernstein 《Behavioral ecology and sociobiology》2007,61(9):1409-1418
The reproductive success of insect parasitoids depends on two activities, searching for hosts to obtain immediate fitness
rewards (offspring) and searching for food to extend life span and enhance future reproductive opportunities. Models suggest
that to deal with this trade-off and to cope with the variability of the resources they depend on, parasitoids should simultaneously
integrate information originating from three distinct sources: host and food availabilities in the environment (environmental
information) and the metabolic reserves of the parasitoid (internal information). We tested whether, in the parasitic wasp
Venturia canescens, these three types of information are perceived simultaneously and interact during host-patch exploitation. Experiments were
performed with strains originating from two different geographical locations and with individuals of the two reproductive
modes, arrhenotoky and thelytoky. We hypothesised that there would be differences between modes of reproduction as they thrive
in different ecological conditions. Our results show that metabolic state, food availability and the number of ovipositions
performed simultaneously modulate patch residence time in V. canescens of both populations and reproductive modes. Unfed wasps left their host patch earlier than fed ones. The tendency to leave
the patch increased with an increasing probability of finding food. Our study confirms that globally, each oviposition increases
the patch-leaving tendency (decremental mechanism). This effect was modulated by both the metabolic reserves and food availability,
and the relationship depended on the geographic origin of populations. Individuals of one of the populations switched from
a decremental to an incremental patch-leaving mechanism depending on the presence or absence of food in the vicinity. Differences
between reproductive modes in the responses to environmental cues can be explained by the different ecological conditions
they live in. 相似文献
179.
The model of Hastings and Powell describes a tritrophic food chain that exhibits chaotic dynamics. The model assumes that the populations are homogeneously mixed, so that the probability that any two individuals interact is uniform and space can be ignored. In this paper we propose a spatial version of the Hastings and Powell model in which predators seek their preys only in a finite neighborhood of their home location, breaking the mixing hypothesis. Treating both space and time as discrete variables we derive a set of coupled equations that describe the evolution of the populations at each site of the spatial domain. We show that the introduction of local predator–prey interactions result in qualitatively distinct dynamics of predator and prey populations. The evolution equations for the predators involve averages over the local density of preys, whereas the equations for the preys involve double averages, where the local density of both preys and predators appear. Our numerical simulations show that local predation also leads to spontaneous pattern formation and to qualitative changes in the global dynamics of the system. In particular, depending on the size of the predation neighborhoods, the chaotic strange attractor present in the original model of Hastings and Powell can be replaced by a stable fixed point or by an attractor of simpler topology. 相似文献
180.
Ecological factors have been claimed paramount for the evolution and maintenance of cooperative group living in eusocial termites, as well as in cooperatively breeding birds and mammals. However, a clear demonstration of the role of any specific ecological factor in termites has been lacking. In the termite Cryptotermes secundus, individuals have two options, staying as helpers at the natal nest or developing into winged sexuals that disperse to found new colonies. An important ecological factor expected to influence the course of termite development is food availability; C. secundus nests inside a single piece of wood that serves as the sole source of food for the duration of the colony. As wood is consumed, the longevity of the colony is reduced, thus diminishing the potential fitness gains of staying at the nest. We experimentally investigated the occurrence of cooperative behavior and development under abundant- and limited-food conditions. Workers exposed to food-limited conditions were more likely to develop into dispersing sexuals and increased selfishly their food-acquisition behaviors. Proximately, a reduced frequency of proctodeal trophallaxis may have interfered with the distribution of pheromones that inhibit sexual development. Ultimately, decreased inclusive fitness benefits in food-limited, and thus short-lived nests, appear to explain the development of dispersing sexuals, supporting (1) the benefits-of-philopatry hypothesis as developed for the occurrence of cooperative breeding in vertebrates, and (2) predictions of reproductive skew theories.Communicated by L. Keller 相似文献