全文获取类型
收费全文 | 58篇 |
免费 | 0篇 |
专业分类
安全科学 | 6篇 |
废物处理 | 5篇 |
环保管理 | 3篇 |
综合类 | 2篇 |
基础理论 | 11篇 |
污染及防治 | 22篇 |
评价与监测 | 4篇 |
社会与环境 | 5篇 |
出版年
2022年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 10篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有58条查询结果,搜索用时 125 毫秒
21.
Ola Flaten Gudbrand Lien Matthias Koesling Anne-Kristin Løes 《Journal of environmental management》2010,91(12):2717-2726
This article examines the characteristics of and reasons for Norwegian farmers’ ceasing or planning to cease certified organic production. We gathered cross-sectional survey data in late 2007 from organic farmers deregistering between January 2004 and September 2007 (n = 220), and similar data from a random sample of farmers with certified organic management in 2006 (n = 407). Of the respondents deregistering by November 2007, 17% had quit farming altogether, 61% now farmed conventionally, and 21% were still farming by organic principles, but without certification. Nearly one in four organic farmers in 2007 indicated that they planned to cease certification within the next 5–10 years. From the two survey samples, we categorised farmers who expect to be deregistered in 5–10 years into three groups: conventional practices (n = 139), continuing to farm using organic principles (uncertified organic deregistrants, n = 105), and stopped farming (n = 33). Of the numerous differences among these groups, two were most striking: the superior sales of uncertified organic deregistrants through consumer-direct marketing and the lowest shares of organic land among conventional deregistrants. We summarised a large number of reasons for deregistering into five factors through factor analysis: economics, regulations, knowledge-exchange, production, and market access. Items relating to economics and regulations were the primary reasons offered for opting out. The regression analysis showed that the various factors were associated with several explanatory variables. Regulations, for example, figured more highly among livestock farmers than crop farmers. The economic factor strongly reflected just a few years of organic management. Policy recommendations for reducing the number of dropouts are to focus on economics, environmental attitudes, and the regulatory issues surrounding certified organic production. 相似文献
22.
Ola M. Fincke 《Behavioral ecology and sociobiology》1984,14(3):235-240
Summary Sperm competition was investigated in the non-territorial damselfly, Enallagma hageni. Using irradiated (sterile) male techniques, the last male to mate was found to fertilize up to 95%
of the eggs of the first clutch laid after mating. Dissection of females collected before, during, and after copula showed that a male removes a maximum of 87% of the sperm by volume of a previous mate. These data verify an earlier estimate of lifetime reproductive success in this species which was based on mating success, and suggest that indirect dissection methods offer minimum estimates of sperm precedence. Male E. hageni have ample opportunity to benefit from sperm precedence, since at least 10% of the receptive females encountered had already mated once that day, but still contained complete or partial clutches of eggs. Female E. hageni benefit directly from high sperm precedence because it allows them to exchange matings for guarding service by males during oviposition bouts under water. 相似文献
23.
Cecilia Kullberg Thord Fransson Johanna Hedlund Niclas Jonzén Ola Langvall Johan Nilsson Kjell Bolmgren 《Ambio》2015,44(1):69-77
Many migratory bird species have advanced their spring arrival during the latest decades, most probably due to climate change. However, studies on migratory phenology in the period before recent global warming are scarce. We have analyzed a historical dataset (1873–1917) of spring arrival to southern and central Sweden of 14 migratory bird species. In addition, we have used relative differences between historical and present-day observations (1984–2013) to evaluate the effect of latitude and migratory strategy on day of arrival over time. There was a larger change in spring phenology in short-distance migrants than in long-distance migrants. Interestingly, the results further suggest that climate change has affected the phenology of short-distance migrants more in southern than in central Sweden. The results suggest that the much earlier calculated arrival to southern Sweden among short-distance migrants mirrors a change in location of wintering areas, hence, connecting migration phenology and wintering range shifts. 相似文献
24.
Color polymorphisms have provided classical examples of how frequency-dependent selection maintains genetic variation in natural
populations. Here we tested for the first time, the hypothesized adaptive function of a female-specific color polymorphism
in odonates to lower male harassment towards females generally. Under conditions controlling for sex ratio, population density
and morph frequency, we also tested two major frequency-dependent selection hypotheses for the maintenance of the polymorphism.
Using groups of captive Enallagma hageni, whose females are either green or a male-like blue, we varied morph frequency at two sex ratios. We quantified sexual harassment
towards females by visual observations, and by the presence of dust on females that was transferred from dusted males. Per
capita harassment rate for the female-monomorphic treatments did not differ from that of the female-polymorphic treatments.
At a male-biased sex ratio, per capita harassment rate towards blue, but not green females increased with morph frequency,
providing partial support for frequency-dependent selection resulting from male learning of female morphs. Even at high frequency,
green females were not harassed more than blue, contrary to the prediction that males should always recognize green females
as mates. Moreover, frequency-dependent harassment towards blue females was not detectable using harassment measured with
dust evidence, which greatly underestimated the incidence of sexual harassment. Our findings identified problems with the
use of insectaries and the dusting technique to quantify male sexual harassment towards females, as well as with a past insectary
experiment on Ischnura elegans that failed to demonstrate frequency-dependent harassment. 相似文献
25.
Mans J. Lindell Gudrun Bremle Ola Broberg Per Larsson 《Ambio-人类环境杂志》2001,30(8):545-551
位于瑞典南部的韦特恩湖是一个大的贫营养化湖泊,它具有高的水面与流域面积比率(大约为0.4)和60年的驻水时间.此湖结合了对大气POP污染的敏感性、对POPs影响的普通敏感性和较慢的浓度降低.提出了鱼体内PCBs和DDT从20世纪60年代一直到1996年的时间系列,以及韦特恩湖沉积物中TCDD的数据,并和其它大湖泊进行了比较.有关北极红点鲑(Salvelinus salvelinus)体内POPs的长期数据集显示每年PCBs有大约5%,DDT有13%的减少.这些速度和其它研究相一致.也讨论了营养物质及其生物效应,以及影响具有长驻水时间的贫营养化湖泊命运的因素.我们提出贫营养的干净湖泊是对于监测生物区中POPs的重要生态系统. 相似文献
26.
Ola M. Fincke 《Behavioral ecology and sociobiology》1982,10(4):293-302
Summary Variance in lifetime mating success was measured for individuals of a population of Enallagma hageni, a non-territorial damselfly in northern Michigan. E. hageni is an explosive breeder with scramble competition for mates. Highly skewed operational sex ratios resulted in intense male-male competition which took the form of interference with tandem pairs. 41% of the males failed to mate in their lifetime as opposed to only 3.6% mating failure in females. The effect on mating success of size, age, longevity, and time spent at the breeding site were investigated. Intermediate sized males obtained the most matings, and male lifetime mating success was highly correlated with longevity. 相似文献
27.
Ola M. Fincke 《Behavioral ecology and sociobiology》1986,18(6):405-412
Summary Female Enallagma hageni oviposit underwater where they are inaccessible to males. I demonstrate that males guard submerged females rather than perch sites, and are behaviorally distinct from lone males at the water. In contrast to lone males, which always attempt to copulate with females presented to them, guarding males exhibit a conditional latency to remating which corresponds closely to the time required by females to oviposit a complete clutch of eggs. By ovipositing underwater, females decrease the risk that their eggs become exposed. Risks associated with submerged oviposition favor both mate guarding, and multiple, within-clutch matings by females. Both guarding mates and lone males rescue females that float on the water surface as the result of improper resurfacing. Such behavior reduces the mortality risk to females from 0.06 to 0.02 per oviposition bout. By remating between bouts, females benefit from the additional vigilance of lone males, who rescue floating females 1.4 times as often as original mates. A second consequence of multiple mating is an increase in the selective advantage of vigilance by mates. Because receptive females become scarce by early afternoon, whereas male density remains high, a male has little (3%) chance of encountering a second receptive female that day. However, he incurs a 42% risk of losing fertilizations if he abandons a mate. For male E. hageni mate guarding functions in the context of both natural and sexual selection. It insures that a mate lives to lay a complete egg clutch in addition to protecting a male's sperm investment. 相似文献
28.
Ola Ullsten James Gustave Speth F.Stuart Chapin III 《Ambio-人类环境杂志》2004,33(6):321-321
位于北极圈及北温带北部的八个国家,其社会和环境正经历着空前的快速变化.对于为什么有些北方国家在面临这些变化时表现出非凡的恢复力而有些却表现得很脆弱,以下的7篇文章对此进行了简明扼要的解释和说明. 相似文献
29.
Amira A. Mohammed Ola A. Abdel Moamen Sayed S. Metwally Ahmed M. El-Kamash Ibrahim Ashour Mohammed S. Al-Geundi 《Environmental science and pollution research international》2020,27(7):6824-6836
Radionuclide sorption by natural and modified clays is extensively accepted to be an important process from the radioactive waste point of view. This work focused on modification of natural attapulgite with a layered double hydroxide to produce a novel chemisorbent for Sr2+, Ni2+, and Co2+ removal from multicomponent solution. The structural and surface characteristics of both attapulgite (ATP) and modified attapulgite (LDH-ATP) were investigated using XRD, FTIR, SEM, and thermal analysis. Comparison of sorption features of Sr2+, Ni2+, and Co2+ onto ATP and LDH-ATP was achieved; the results indicated that LDH-ATP was the most efficient sorbent for Sr2+, Ni2+, and Co2+. Kinetic studies established that the sorption is fast and reaching >90% within 30 min. The sorption of Sr2+, Ni2+, and Co2+ are well defined by non-linear pseudo-second-order model and controlled by an intra-particle diffusion mechanism. The diffusivity was determined using homogeneous surface diffusion (HSDM) model and found in the order 10−13 m2/min; this confirmed that the sorption of the three ions is chemisorption process. LDH-ATP can be employed as a candidate chemisorbent for the removal of some metal ions from waste solution. 相似文献
30.
Vertical diffusivity and oxygen consumption in the basin water, the water below the sill level at about 59 m depth, have been estimated by applying budget methods to monitoring data from hydrographical stations BY4 and BY5 for periods without water renewal. From the vertical diffusivity, the mean rate of work against the buoyancy forces below 65 m depth is estimated to about 0.10 mW m−2. This is slightly higher than published values for East Gotland Sea. The horizontally averaged vertical diffusivity κ can be approximated by the expression κ = a0N−1 where N is the buoyancy frequency and a0 ≈ 1.25 × 10−7 m2 s−2, which is similar to values for a0 used for depths below the halocline in Baltic proper circulation models for long-term simulations. The contemporary mean rate of oxygen consumption in the basin water is about 75 g O2 m−2 year−1, which corresponds to an oxidation of 28 g C m−2 year−1. The oxygen consumption in the Bornholm Basin doubled from the 1970s to the 2000s, which qualitatively explains the observed increasing frequency and vertical extent of anoxia and hypoxia in the basin water in records from the end of the 1950s to present time. A horizontally averaged vertical advection–diffusion model of the basin water is used to calculate the effects on stratification and oxygen concentration by a forced pump-driven vertical convection. It is shown that the residence time of the basin water may be reduced by pumping down and mixing the so-called winter water into the deepwater. With the present rate of oxygen consumption, a pumped flux of about 25 km3 year−1 would be sufficient to keep the oxygen concentration in the deepwater above 2 mL O2 L−1. 相似文献