全文获取类型
收费全文 | 221篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
废物处理 | 15篇 |
环保管理 | 15篇 |
综合类 | 93篇 |
基础理论 | 27篇 |
污染及防治 | 49篇 |
评价与监测 | 13篇 |
社会与环境 | 10篇 |
出版年
2020年 | 2篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 6篇 |
2012年 | 6篇 |
2011年 | 7篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 13篇 |
2003年 | 4篇 |
2002年 | 9篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1988年 | 2篇 |
1983年 | 3篇 |
1978年 | 2篇 |
1966年 | 3篇 |
1965年 | 2篇 |
1964年 | 4篇 |
1961年 | 5篇 |
1960年 | 3篇 |
1959年 | 6篇 |
1957年 | 4篇 |
1955年 | 3篇 |
1954年 | 3篇 |
1952年 | 4篇 |
1950年 | 3篇 |
1948年 | 2篇 |
1942年 | 1篇 |
1941年 | 1篇 |
1933年 | 1篇 |
1931年 | 1篇 |
1925年 | 1篇 |
1920年 | 1篇 |
1915年 | 1篇 |
排序方式: 共有222条查询结果,搜索用时 31 毫秒
71.
The Science of Nature - 相似文献
72.
73.
74.
75.
We conducted a pilot-scale study at a research facility in southeastern Connecticut to assess the effects of leachfield aeration on removal of nutrients and pathogens from septic system effluent. Treatments consisted of lysimeters periodically aerated to maintain a headspace O(2) concentration of 0.209 mol mol(-1) (AIR) or vented to an adjacent leachfield trench (LEACH) and were replicated three times. All lysimeters were dosed with effluent from a septic tank for 24 mo at a rate of 12 cm d(-1) and subsequently for 2 mo at 4 cm d(-1). LEACH lysimeters had developed a clogging mat, or biomat, 20 mo before the beginning of our study. The level of aeration in the AIR treatment was held constant regardless of loading rate. No conventional biomat developed in the AIR treatment, whereas a biomat was present in the LEACH lysimeters. The headspace of LEACH lysimeters was considerably depleted in O(2) and enriched in CH(4), CO(2), and H(2)S relative to AIR lysimeters. Drainage water from AIR lysimeters was saturated with O(2) and had significantly lower pH, five-day biological oxygen demand (BOD(5)), and ammonium, and higher levels of nitrate and sulfate than LEACH lysimeters regardless of dosing rate. By contrast, significantly lower levels of total N and fecal coliform bacteria were observed in AIR than in LEACH lysimeters only at the higher dosing rate. No significant differences in total P removal were observed. Our results suggest that aeration may improve the removal of nitrogen, BOD(5), and fecal coliforms in leachfield soil, even in the absence of a biomat. 相似文献
76.
Sandra Steiger Klaus Peschke Josef K. Müller 《Behavioral ecology and sociobiology》2008,62(7):1053-1060
Nestmate recognition in eusocial insects has received a lot of attention in the last decades. Recognition in subsocial species,
in contrast, has been ignored almost completely and consequently, and little is known about proximate mechanisms of recognition
in subsocial systems. We studied one subsocial species, the biparental brood caring burying beetle Nicrophorus vespilloides, an interesting model organism for studies of recognition because of its ability to discriminate between breeding partners
and conspecific competitors. Recognition appears to be based on a chemical cue closely linked to the breeding status of individuals.
Breeding and non-breeding beetles consistently differ in their relative proportions of polyunsaturated cuticular hydrocarbons.
To investigate the function of these polyenes in the burying beetles’ recognition system, we quantified their concentration
on the cuticle during the early state of a breeding attempt and tested the response of breeding beetles in corresponding behavioural
experiments. We observed a rapid increase in the proportion of polyunsaturated hydrocarbons of both males and females after
they were provided with a carcass suitable for reproduction. Furthermore, we found that the relative amount of polyenes on
an individual’s surface was closely correlated with its chance of being accepted as breeding partner. Our results support
the idea that polyunsaturated hydrocarbons are involved in breeding partner recognition in N. vespilloides, functioning as a signal that conveys information about the individual’s breeding status. Breeding females have greater amount
of polyenes than breeding males, and females ingest more carrion during the first days on the carcass, which supports our
hypothesis that precursors for the respective polyenes are derived from ingested carrion. 相似文献
77.
Petr Babula Vojtech Adam Radka Opatrilova Josef Zehnalek Ladislav Havel Rene Kizek 《Environmental Chemistry Letters》2008,6(4):189-213
Heavy metals still represent a group of dangerous pollutants, to which close attention is paid. Many heavy metals are essential
as important constituents of pigments and enzymes, mainly zinc, nickel and copper. However, all metals, especially cadmium,
lead, mercury and copper, are toxic at high concentration because of disrupting enzyme functions, replacing essential metals
in pigments or producing reactive oxygen species. The toxicity of less common heavy metals and metalloids, such as thallium,
arsenic, chromium, antimony, selenium and bismuth, has been investigated. Here, we review the phytotoxicity of thallium, chromium,
antimony, selenium, bismuth, and other rare heavy metals and metalloids such as tellurium, germanium, gallium, scandium, gold,
platinum group metals (palladium, platinum and rhodium), technetium, tungsten, uranium, thorium, and rare earth elements yttrium
and lanthanum, and the 14 lanthanides cerium, dysprosium, erbium, europium, gadolinium, holmium, lutetium, neodymium, promethium,
praseodymium, samarium, terbium, thulium and ytterbium. 相似文献
78.
79.
80.
Zuzana Hrevuov Michal Hejcman Vilm V. Pavl Josef Hakl Michaela Klaudisov Jií Mrkvi
ka 《Agriculture, ecosystems & environment》2009,130(3-4):123-130
The resilience, the ability of an ecosystem to recover after termination of perturbation, of highly productive Alopecurus grassland was investigated after the cessation of the following long-term fertilizer treatments applied under a two- or three-cut management regime: unfertilized control, PK, N100PK, N200PK, N300PK and N400PK. Annual application rates of pure nutrients per hectare were 0–400 kg for N, 40 kg for P and 100 kg for K. The dynamics of biomass production were measured for 16 years and the effect of former fertilizer treatments on soil chemical properties, biomass chemical properties, plant species composition and species richness were investigated 16 years after the last application of fertilizers. It was concluded that 16 years was not long enough to achieve resilience in plant-available soil P and K concentrations, N/P ratios in the plant biomass or plant species composition, but that it was long enough to achieve resilience in species richness. In the case of biomass production the effect of former fertilizer treatments was apparent in 10 of the 16 seasons investigated, indicating that resilience in biomass production must be evaluated using data from more than 1 vegetation season. The results of the study stress the necessity for long-term research because of high year-to-year variability in biomass production as well as long-term after-effects of fertilizer treatments in alluvial grassland. 相似文献