全文获取类型
收费全文 | 181篇 |
免费 | 2篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 5篇 |
废物处理 | 4篇 |
环保管理 | 10篇 |
综合类 | 48篇 |
基础理论 | 32篇 |
污染及防治 | 60篇 |
评价与监测 | 18篇 |
社会与环境 | 11篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 13篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 12篇 |
2008年 | 9篇 |
2007年 | 7篇 |
2006年 | 10篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有188条查询结果,搜索用时 15 毫秒
31.
32.
We provide evidence for the proximate role of food in sex allocation by an ant species, and demonstrate how identity of the homopteran partner affects benefits to colonies of a plant-symbiotic ant. The system studied includes a plant-ant that nests in swollen hollowed internodes of a myrmecophyte, and two species of homopteran trophobionts (a coccid and a pseudococcid) tended inside domatia by these ants, for which they are an essential source of food. Total investment in pupae was greater for ant colonies that tended solely or primarily coccids than for those that tended pseudococcids. In particular, biomass invested in sexuals increased more rapidly with size of the colony in trees where ants tended coccids. This greater investment in sexuals was not made at the expense of investment in workers, but reflected increased resources available to coccid-tending colonies. Higher reproductive output indicates that ant fitness may be greater when they tend coccids. These additional resources led to a greater increase in production of alate females than in that of males. Consequently, the sex investment ratio of coccid-tending colonies was more female biased than in those that tended pseudococcids. Differences in resource supply affected numbers of individuals produced but not per-individual investment, with one partial exception: in very small colonies, pseudococcid-tending colonies produced small workers while coccid-tending colonies did not, further underlining the higher resource supply to coccid-tending colonies. This study provides evidence for the proximate role played by food in sex allocation at the colony level. We discuss our results in the context of hypotheses aimed at explaining sex ratio at the colony and population levels. 相似文献
33.
Decay of cacti and carbon cycling 总被引:2,自引:0,他引:2
Garvie LA 《Die Naturwissenschaften》2006,93(3):114-118
Cacti contain large quantities of Ca-oxalate biominerals, with C derived from atmospheric CO2. Their death releases these biominerals into the environment, which subsequently transform to calcite via a monohydrocalcite
intermediate. Here, the fate of Ca-oxalates released by plants in arid environments is investigated. This novel and widespread
form of biomineralization has unexpected consequences on C cycling and calcite accumulation in areas with large numbers of
cacti. The magnitude of this mineralization is revealed by studying the large columnar cactus Carnegiea gigantea (Engelm.) Britton and Rose in southwestern Arizona (locally called the saguaro). A large C. gigantea contains on the order of 1×105 g of the Ca-oxalate weddellite—CaC2O4·2H2O. In areas with high C. gigantea density, there is an estimated 40 g Catm m−2 sequestered in Ca-oxalates. Following the death of the plant, the weddellite transforms to calcite on the order to 10–20 years.
In areas with high saguaro density, there is an estimated release of up to 2.4 g calcite m−2 year−1 onto the desert soil. Similar transformation mechanisms occur with the Ca-oxalates that are abundant in the majority of cacti.
Thus, the total atmospheric C returned to the soil of areas with a high number density of cacti is large, suggesting that
there may be a significant long-term accumulation of atmospheric C in these soils derived from Ca-oxalate biominerals. These
findings demonstrate that plant decay in arid environments may have locally significant impacts on the Ca and inorganic C
cycles. 相似文献
34.
Nitrate in groundwater: an isotopic multi-tracer approach 总被引:12,自引:0,他引:12
Widory D Kloppmann W Chery L Bonnin J Rochdi H Guinamant JL 《Journal of contaminant hydrology》2004,72(1-4):165-188
In spite of increasing efforts to reduce nitrogen inputs into groundwater from intensive agriculture, nitrate (NO3) remains one of the major pollutants of drinking-water resources worldwide. Determining the source(s) of NO3 contamination in groundwater is an important first step for improving groundwater quality by emission control, and it is with this aim that we investigated the viability of an isotopic multi-tracer approach (delta15N, delta11B, 87Sr/86Sr), in addition to conventional hydrogeologic analysis, in two small catchments of the Arguenon watershed (Brittany, France). The main anthropogenic sources (fertilizer, sewage effluent, and hog, cattle and poultry manure) were first characterized by their specific B, N and Sr isotope signatures, and compared to those observed in the ground- and surface waters. Chemical and isotopic evidence shows that both denitrification and mixing within the watershed have the effect of buffering NO3 contamination in the groundwater. Coupled delta11B, delta15N and 87Sr/86Sr results indicate that a large part of the NO3 contamination in the Arguenon watershed originates from the spreading of animal manure, with hog manure being a major contributor. Point sources, such as sewage effluents, contribute to the NO3 budget of the two watersheds. 相似文献
35.
Salps have higher filtration rates than most other holoplankton, and are capable of packaging and exporting primary production
from surface waters. A method of kinematic analysis was employed to accurately measure salp feeding rates. The data were then
used to explain how diverse body morphologies and swimming motions among species and lifecycle stages influence salp feeding
performance. We selected five species, representing a range of morphologies and swimming styles, and used digitized outlines
from video frames to measure body-shape change during a pulse cycle. Time-varying body volume was then calculated from the
digitized salp outlines to estimate the amount of fluid passing through the filtering mesh. This non-invasive method produced
higher feeding rates than other methods and revealed that body volume, pulse frequency and degree of contraction are important
factors for determining volume filtered. Each species possessed a unique combination of these three characteristics that resulted
in comparable filtration (range: 0.44–15.33 ml s−1) and normalized filtration rates (range: 0.21–1.27 s−1) across species. The convergence of different species with diverse morphologies on similar normalized filtration suggests
a tendency towards a flow optimum. 相似文献
36.
Helmi K Skraber S Burnet JB Leblanc L Hoffmann L Cauchie HM 《Environmental monitoring and assessment》2011,179(1-4):163-175
Starting in 2006, a monitoring of Giardia lamblia and Cryptosporidium parvum occurrence was conducted for 2 years in the largest drinking water reservoir of Luxembourg (Esch-sur-S?re reservoir) using microscopy and qPCR techniques. Parasite analyses were performed on water samples collected from three sites: site A located at the inlet of the reservoir, site B located 18 km downstream site A, at the inlet of the drinking water treatment plant near the dam of the reservoir and site C where the finished drinking water is injected in the distribution network. Results show that both parasites are present in the reservoir throughout the year with a higher occurrence of G. lamblia cysts compared to C. parvum oocysts. According to our results, only 25% of the samples positive by microscopy were confirmed by qPCR. (Oo)cyst concentrations were 10 to 100 times higher at site A compared to site B and they were positively correlated to the water turbidity and negatively correlated to the temperature. Highest (oo)cyst concentrations were observed in winter. In contrast, no relationship between the concentrations of (oo)cysts in the reservoir and rain events could be established. Though a correlation has been observed between both parasites and faecal indicators in the reservoir, some discrepancies highlight that the latter do not represent a reliable tool to predict the presence/absence of these pathogenic protozoa. In summer 2007, the maximal risk of parasite infection per exposure event for swimmers in the reservoir was estimated to be 0.0015% for C. parvum and 0.56% for G. lamblia. Finally, no (oo)cysts could be detected in large volumes of finished drinking water. 相似文献
37.
Sam Provoost M. Laurence M. Jones Sally E. Edmondson 《Journal of Coastal Conservation》2011,15(1):207-226
In coastal dunes, landscape changes are a rule, rather than an exception. This paper gives an overview of changes in landscape
and vegetation with a focus on the past century. The history of dunes is characterised by phases of sand drift, alternated
with geomorphological stability. The historical development of dune woodland during these stable phases has been documented
for sites all over Europe. Vegetation reconstructions of historical open dune habitats however is very difficult due to limited
preservation of fossil remains. People have drastically altered coastal dune landscapes through centuries of exploitation
and more recently development of the coast. Historical land use has generally pushed vegetation back into a semi-natural state.
During roughly the past century a tendency of increasing fixation and succession is observed on coastal dunes throughout northwest
Europe. Six causes of change are discussed. 1) Changes in land use, mainly abandonment of agricultural practices, have led
to the development of late successional stages such as scrub and woodland. 2) Crashing rabbit populations due to myxomatosis
in the 1950s caused vigorous grass growth and probably stimulated scrub development. 3) A general tendency of landscape fixation
is observed due to both natural and anthropogenic factors. 4) Eutrophication, mainly due to atmospheric nitrogen deposition
is clearly linked to grass encroachment on acidic but also on some calcareous dunes. 5) The impact of climate change on vegetation
is still unclear but probably lengthening of growing season and maybe enhanced CO2 concentrations have led to an acceleration of succession. 6) A general anthropogenisation of the landscape occurs with rapid
spread of non-native species as an important consequence. The reconstruction of a natural reference landscape is considered
largely unattainable because of irreversible changes and the long tradition of human impact, in many cases since the development
of the dunes. Two contradictory elements need reconciliation. First, the general acceleration of succession and scrub and
woodland development in particular is partly caused by a decreased anthropogenic interference in the landscape and deserves
more appreciation. Second, most biodiversity values are largely linked to open, early succession dune habitats and are threatened
by the same tendency. Apart from internal nature management, in which grazing plays an important part, re-mobilisation of
stable, senescent dunes is an important challenge for dune management. 相似文献
38.
Olivier Roux Charles Gers Josèphe Nathan Tene-Ghomsi Laurence Arvanitakis Dominique Bordat Luc Legal 《Chemoecology》2007,17(1):13-18
Summary. Cotesia plutellae is a specialist parasitoid of Plutella xylostella. This specificity is potentially under the control of several factors before and after oviposition. Thereby, the stimuli
that lead female parasitoids to host locations and to oviposition, might be at the basis of the specificity. We explore here
the response of C. plutellae females exposed to host cuticular lipids. A total cuticular lipid extract of host caterpillars was fractionated into a hydrocarbon
fraction and a non-hydrocarbon fraction. Neither fraction alone had any effect on oviposition behaviour in C. plutellae but the hydrocarbon fraction alone did seem to have a positive effect on the rate of antennal contact by the females. To
induce oviposition behaviour, both fractions were necessary and reflect cooperation between at least one compound in each
fraction. Identification of cuticular lipids shows that hydrocarbons were dominant (77%). Non-hydrocarbon compounds were mainly
represented by 15-nonacosanone (18% of the total lipid extract). This ketone is rare in insect cuticle lipids and is thought
to originate from the cabbage epicuticle where it is dominant with n-C29 and 14- and 15-nonacosanol also found among the cuticular lipids of the host caterpillar. 相似文献
39.
Roussel S Reboux G Bellanger AP Sornin S Grenouillet F Dalphin JC Piarroux R Millon L 《Journal of environmental monitoring : JEM》2008,10(6):724-729
Dwellings showing a presence of moulds are considered to be unhealthy both by the inhabitants and by sanitary authorities. Although the thresholds of pathogenicity have not yet been established, the toxic, allergic and infectious risk of indoor moulds is better understood today. A study on indoor fungi contamination for 128 dwellings was done between October and May in France. It concerned 69 dwellings, the occupants of which either complained to the sanitary authorities about problems of moulds and humidity or consulted a doctor who related their symptoms to housing conditions. Fifty-nine other dwellings, the occupants of which were healthy, constituted the control group. We present the statistical analysis of questionnaires, which aimed to clarify characteristics of dwellings associated with high concentrations of airborne moulds. Air samples were taken with an impactor in 500 rooms. On visiting dwellings, investigators obtained answers to 25 questions concerning characteristics of inhabitants and living space, as well as the presence of mould indicators. Indoor and outdoor temperature and indoor relative humidity of air measurements were taken. The total concentration of fungi in the air was significantly higher in ground floor apartments versus those on other floors (p = 0.047), in small and highly occupied dwellings (p = 0.03 and 0.003), in dwellings with electric heating (p = 0.04), without a ventilation system (p = 0.003), with water damage (p = 0.003), and finally, in those where the investigator noted an odour of moisture or visible moulds (p < 0.001). The efficacy of the latter criteria in the evaluation of insalubrity is discussed. 相似文献
40.