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131.
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Amanda J. Hess Peggy A. Johnson 《Journal of the American Water Resources Association》2001,37(1):213-221
ABSTRACT: The environment surrounding urban streams imposes constraints upon stream enhancement projects. Constraints include bridges, culverts, highways, sewer and water lines, lack of easements, and other floodplain structures. The consequences of failure of these infrastructure constraints can be significant and should be considered in the design process. Fault tree analysis provides a systematic technique for analyzing the interactions of events that could lead to infrastructure failure. A case study of a stream in Pittsburgh, Pennsylvania, shows that fault tree analysis can effectively model the interactions between the stream system and the infrastructure constraints and predict the most likely modes of failure. In addition, the relative success of alternative designs and failure mitigation techniques can be assessed using this analysis tool, lending insight into the urban stream enhancement design process. The method could also provide justification in the design permitting process and input for risk assessment. 相似文献
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Current United States National Park Service (NPS) management is challenged to balance visitor use with the environmental and
social consequences of automobile use. Wildlife populations in national parks are increasingly vulnerable to road impacts.
Other than isolated reports on the incidence of road-related mortality, there is little knowledge of how roads might affect
wildlife populations throughout the national park system. Researchers at the Western Transportation Institute synthesized
information obtained from a system-wide survey of resource managers to assess the magnitude of their concerns on the impacts
of roads on park wildlife. The results characterize current conditions and help identify wildlife-transportation conflicts.
A total of 196 national park management units (NPS units) were contacted and 106 responded to our questionnaire. Park resource
managers responded that over half of the NPS units’ existing transportation systems were at or above capacity, with traffic
volumes currently high or very high in one quarter of them and traffic expected to increase in the majority of units. Data
is not generally collected systematically on road-related mortality to wildlife, yet nearly half of the respondents believed
road-caused mortality significantly affected wildlife populations. Over one-half believed habitat fragmentation was affecting
wildlife populations. Despite these expressed concerns, only 36% of the NPS units used some form of mitigation method to reduce
road impacts on wildlife. Nearly half of the respondents expect that these impacts would only worsen in the next five years.
Our results underscore the importance for a more systematic approach to address wildlife-roadway conflicts for a situation
that is expected to increase in the next five to ten years. 相似文献
135.
Turner syndrome (TS), a common chromosomal abnormality affecting females, is associated with partial or complete loss of the second sex chromosome. Although the classic karyotype is 45, X, the detection of mosaic TS is increasing. TS is a multi-system disorder with significant endocrine, cardiovascular and reproductive impacts. Accelerated ovarian follicular loss leads to primary amenorrhoea or premature ovarian insufficiency and infertility. Early diagnosis and counselling regarding hormone replacement therapy and future reproductive capacity, including fertility preservation, are essential to improve reproductive outcomes. Pubertal induction or estrogen replacement is usually required to optimise long-term health outcomes; however, initiation may be delayed due to delayed diagnosis. Spontaneous pregnancy occurs in a small number of women; however, many require donor oocytes and assisted reproductive technology to achieve a pregnancy. Pregnancy is a high risk especially when associated with congenital heart disease. Prepregnancy counselling by the multidisciplinary team (MDT) to identify contraindications and optimise pre-existing health issues is essential. Pregnancy management should be led by a maternal-fetal medicine unit with input from the MDT. This review examines reproductive health outcomes in women with TS and how best to manage them to reduce health risks and improve maternal and neonatal outcomes. 相似文献
136.
New highly fluorinated monodentate and bidentate phosphine oxide compounds of the type {CF(3)(CF(2))(n)CH(2)CH(2)}(3)PO (n = 5, 9) and [{CF(3)(CF(2))(5)CH(2)CH(2)}(2)P(O)CH(2)CH(2)P(O){CH(2)CH(2)(CF(2))(5)CF(3)}] have been prepared. Their ability to extract a number of metals and radionuclides from aqueous solutions into perfluorinated solvents has been established and the extractable species investigated. All extractants extract the metals As(V), Cd(II), Co(II), Cr(VI), Hg(II), Pb(II), and Sn(II) with >75% removal. In addition, the radioisotopes (90)Sr(II), (133)Ba(II), and U(VI) have been investigated, whilst (59)Fe(III) has been used to model the extraction of plutonium. (133)Ba(II) shows a high distribution ratio for monodentate phosphine oxides, whilst for UO(2)(2+) and (59)Fe(III) bidentate phosphine oxides are superior. 相似文献
137.
D.Y.C. Leung Daniel Yung Amanda Ng M.K.H. Leung Alan Chan 《Environmental Science & Policy》2009,12(1):92-101
With the approval of the Chinese central government, the Government of the Hong Kong Special Administrative Region (HKSAR) decided to participate in a regional emissions trading (ET) pilot scheme in the Pearl River Delta (PRD) region. This scheme, instead of aiming to curb global warming, is geared mostly toward reducing air pollutant (that is, SO2, NOx, RSP, and VOCs) emissions by 20–55% by 2010, thus improving air quality in the region. Both the HKSAR and the Guangdong Provincial Governments will impose emission caps on their respective power plants in the region and allocate emissions credits to them. This study explores the background of this regional ET scheme and correlates it with the emissions reduction scenario to provide more details for assessing its applicability to Hong Kong and Guangdong Province. Although practicing ET in the PRD region presents many challenges, establishing an appropriate ET scheme is of paramount importance for Hong Kong, as well as other cities in the PRD region, to achieve a sustainable air quality. 相似文献
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Surface-active organic molecules (surfactants) may influence the ability of an aerosol particle to act as a cloud condensation nuclei by reducing its surface tension. One source of organic mass in aerosol particles, which may also contain surfactants, is bubble bursting on the sea surface. In order to directly compare these molecules in the ocean and aerosol particles, we developed a method using multiple solid phase extractions and high resolution mass spectrometry to characterize surface active organic molecules in both. This method has extraction efficiencies greater than 85%, 75%, and 60% for anionic, cationic, and nonionic surfactant standards, respectively. In this study, we demonstrate the presence of three ionic classes of surface active organics in atmospheric aerosol particles and estuarine water from Skidaway Island, GA. With this extraction method, organic molecules from both estuarine water and atmospheric aerosol particles significantly reduced surface tension of pure water (surface tension depression of ~ 18 mN/m) and had high ratios of hydrogen to carbon (H/C) and low ratios of oxygen to carbon (O/C), indicative of surfactants. While previous work has observed a larger fraction of anionic surface active organics in seawater and marine aerosol particles, here we show cationic surface active organics may make up a large fraction of the total surface active molecules in estuarine water (43%–47%). 相似文献