全文获取类型
收费全文 | 97篇 |
免费 | 3篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 1篇 |
废物处理 | 3篇 |
环保管理 | 24篇 |
综合类 | 13篇 |
基础理论 | 21篇 |
污染及防治 | 25篇 |
评价与监测 | 7篇 |
社会与环境 | 9篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 13篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 2篇 |
2012年 | 10篇 |
2011年 | 12篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 1篇 |
2002年 | 3篇 |
2001年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
排序方式: 共有103条查询结果,搜索用时 31 毫秒
31.
Darrell J. Kemp Joseph M. Macedonia Tamara S. Ball Ronald L. Rutowski 《Behavioral ecology and sociobiology》2008,62(6):1017-1026
Female mate choice has been shown to provide direct mating benefits in several animal groups. In butterflies, for which there
are increasing reports of fine-scale color-based mate choice, the evolutionary benefits that accrue from such mating biases,
if any, are largely unknown. We addressed this issue in the butterfly Colias eurytheme, a species in which females choose mates on the basis of iridescent ultraviolet (UV) wing ornamentation and in which males
donate reproductively beneficial nuptial gifts. In the first experiment, we assessed the mass of gifts donated to 77 virgin
females by males sampled directly from a field encounter site. Despite large variance in the male adult phenotype and ejaculate,
no single aspect of dorsal wing coloration, including UV brightness, chroma, or hue, was related to ejaculate mass. There
was, however, an interesting interaction between the effects of male body size and copula duration upon ejaculate mass, with
size scaling positively with ejaculate mass among males involved in shorter copulations (those lasting <70 min) but negatively
among males in longer copulations. In the second experiment, we assessed the lifetime fecundity, fertility, and longevity
of 85 females mated under similar circumstances to free-flying wild males. Although several wing color parameters proved subtly
informative in more sophisticated multivariable models, no model predicted more than about 20% of the variation in any single
female fitness parameter. The duration of copulation, which ranged from 35 min to over 16 h and which carries putative costs
for females, was, again, only very weakly predicted by male wing color parameters (i.e., R
2 = 0.089). Given the overall minor predictive power of male wing coloration in general and of UV brightness in particular,
our results do not strongly support the hypothesis that female C. eurytheme prefer bright UV males to obtain direct benefits or to minimize the costs associated with lengthy copulations. 相似文献
32.
Tamara Metze 《Journal of Environmental Policy & Planning》2017,19(1):35-52
The meaning of hydraulic fracturing for shale gas is contested worldwide: is it an energy game changer, a transition fuel, or a technology that poses severe environmental problems? In the Netherlands, a policy controversy developed in which fracturing was reframed from ‘business as usual’ to a potential environmental risk. This article theoretically and empirically describes this shift by arguing that the technology of hydraulic fracturing for shale gas is a boundary object that created a sphere of engagement for all sorts of actors. In this sphere, they negotiated a common but soft meaning of this technology. These negotiations consisted of frame contests. As part of those contests, the discursive strategies of framing and boundary work enabled opponents to create uncertainty about economic benefits and environmental impact. The shift in meaning transformed the issue from an economic one with standard governmental rules and regulations into a planning issue that needs more precaution. 相似文献
33.
Ilaria Fantasia Silvia Catagini Giulia Zamagni Pantaleo Greco Irene Bianchini Sofia Bussolaro Mariachiara Quadrifoglio Leila Lo Bello Lorenzo Monasta Giuseppe Ricci Flavio Faletra Agnese Feresin Tamara Stampalija 《黑龙江环境通报》2023,43(7):929-936
Objectives
To evaluate the clinical significance of nuchal translucency (NT) between the 95th–99th percentile in terms of typical and atypical chromosomal abnormalities (ACAs), associated fetal congenital defects and postnatal outcome.Methods
A retrospective cohort study of fetuses with NT between the 95th–99th percentile. Data regarding the rate of associated fetal defects, genetic abnormalities and postnatal outcome were collected.Results
A total of 306 cases of fetuses with an NT between the 95th–99th percentiles were included. The overall rate of genetic abnormalities was 12.1% (37/306). Chromosomal abnormalities were found in 10.1% (31/306) of cases and 2% were ACA (6/306). Within this group, two were pathogenic Copy Number Variants (CNVs) and four were single gene disorders. The overall rate of fetal congenital defects was 13.7% (42/306). All ACAs were found in fetuses with congenital defects. Postnatally, a new diagnosis of a single gene disorder was made in 0.85% of cases (2/236).Conclusions
The presence of an NT between the 95th–99th percentiles carries a 10-fold increased risk of fetal defects, representing an indication for referral for a detailed fetal anatomy evaluation. The risk of ACA is mainly related to the presence of fetal defects, irrespective of the combined test risk. 相似文献34.
Ragosta G Evensen C Atwill ER Walker M Ticktin T Asquith A Tate KW 《Journal of environmental management》2011,92(8):1910-1915
Associations were examined between riparian canopy cover, presence of cattle near streams, and month of year with the concentration of Enterococcus (Most Probable Number (MPN)/100 ml) in surface water at Waipā watershed on the North Side of the Hawaiian island Kaua'i. Each one percent decrease in riparian canopy cover was associated with a 3.6 MPN/100 ml increase of waterborne Enterococcus. Presence of cattle near monitoring sites was associated with an increase of 99.3 MPN/100 ml of Enterococcus in individual grab samples. Lastly, summer samples (July) were substantially higher in concentration of Enterococcus than winter collected samples (February) in Enterococcus in sampled streams. These results suggest that reducing canopy cover and introduction of cattle into riparian zones may contribute to increases of Enterococcus concentrations in stream water. 相似文献
35.
Ehlers Sonja M. Al Najjar Tamara Taupp Thomas Koop Jochen H. E. 《Environmental science and pollution research international》2020,27(18):22380-22389
Environmental Science and Pollution Research - Caddisfly larvae occur in streams and rivers, and many caddisfly species build protective cases using material from their habitat such as sand grains.... 相似文献
36.
37.
Denitrification in alluvial wetlands in an urban landscape 总被引:1,自引:0,他引:1
Harrison MD Groffman PM Mayer PM Kaushal SS Newcomer TA 《Journal of environmental quality》2011,40(2):634-646
Riparian wetlands have been shown to be effective "sinks" for nitrate N (NO3-), minimizing the downstream export of N to streams and coastal water bodies. However, the vast majority of riparian denitrification research has been in agricultural and forested watersheds, with relatively little work on riparian wetland function in urban watersheds. We investigated the variation and magnitude of denitrification in three constructed and two relict oxbow urban wetlands, and in two forested reference wetlands in the Baltimore metropolitan area. Denitrification rates in wetland sediments were measured with a 15N-enriched NO3- "push-pull" groundwater tracer method during the summer and winter of 2008. Mean denitrification rates did not differ among the wetland types and ranged from 147 +/- 29 microg N kg soil(-1) d(-1) in constructed stormwater wetlands to 100 +/- 11 microg N kg soil(-1) d(-1) in relict oxbows to 106 +/- 32 microg N kg soil(-1) d(-1) in forested reference wetlands. High denitrification rates were observed in both summer and winter, suggesting that these wetlands are sinks for NO3- year round. Comparison of denitrification rates with NO3- standing stocks in the wetland water column and stream NO3- loads indicated that mass removal of NO3- in urban wetland sediments by denitrification could be substantial. Our results suggest that urban wetlands have the potential to reduce NO3- in urban landscapes and should be considered as a means to manage N in urban watersheds. 相似文献
38.
39.
Fetal tumors represent an infrequent pathology when compared to congenital malformations, although their true incidence may be underestimated. A variety of benign and malignant neoplasms may occur anywhere in the neural axis. Imaging plays an important role in the fetal tumor diagnosis and evaluation of their resultant complications. Discovery of a fetal mass on obstetric ultrasound necessitates further evaluation with prenatal magnetic resonance imaging (MRI). New MR sequences and new applications of existing techniques have been successfully implemented in prenatal imaging. A detailed assessment may be performed using a variety of MR. Fetal tumors may be histologically benign or malignant, but their prognosis generally remains poor, especially for intracranial lesions. Unfavorable tumor location or heightened metabolic demands on a developing fetus may result in severe complications and a fatal outcome, even in cases of benign lesions. Nowadays, prenatal treatment focuses mainly on alleviation of secondary complications caused by the tumors. In this article we review congenital tumors of the brain, face, and neck encountered in prenatal life, and discuss diagnostic clues for appropriate diagnosis. 相似文献