首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   117篇
  免费   4篇
安全科学   4篇
废物处理   2篇
环保管理   26篇
综合类   4篇
基础理论   15篇
污染及防治   64篇
评价与监测   3篇
社会与环境   3篇
  2022年   1篇
  2021年   1篇
  2019年   6篇
  2018年   1篇
  2017年   3篇
  2016年   1篇
  2015年   2篇
  2014年   1篇
  2013年   20篇
  2012年   5篇
  2011年   1篇
  2010年   2篇
  2009年   4篇
  2008年   4篇
  2007年   9篇
  2006年   3篇
  2005年   4篇
  2004年   8篇
  2003年   2篇
  2002年   1篇
  2001年   6篇
  2000年   7篇
  1999年   1篇
  1998年   1篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
  1989年   1篇
  1986年   3篇
  1984年   2篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1969年   1篇
排序方式: 共有121条查询结果,搜索用时 12 毫秒
61.
The Klippel-Trenaunay-Weber syndrome is a complex developmental disorder of the vascular and skeletal systems. While many features of the syndrome are congenital, it has not been diagnosed often before birth. This paper describes a case of Klippel-Trenaunay-Weber syndrome diagnosed at 19 weeks' gestation on the basis of sonographic findings and family history. The clinical variability of the syndrome is emphasized and the importance of family history in differential diagnosis is stressed.  相似文献   
62.
The suitability of a granulated zero valent iron (ZVI) permeable reactive barrier (PRB) remediation strategy was investigated for tribromoethene (TriBE), cis-1,2-dibromoethene (c-DBE), trans-1,2-dibromoethene (t-DBE) and vinyl bromide (VB), via batch and large-scale column experiments that were subsequently analysed by reactive transport modelling.The brominated ethenes in both batch and large-scale column experiments showed rapid (compared to controls and natural attenuation) degradation in the presence of ZVI. In the large-scale column experiment, degradation half-lives were 0.35 days for TriBE, 0.50 days for c-DBE, 0.31 days for t-DBE and 0.40 days for VB, under site groundwater flow conditions, resulting in removal of brominated ethenes within the first 0.2 m of a 1.0 m thick ZVI layer, indicating that a PRB groundwater remediation strategy using ZVI could be used successfully.In the model simulations of the ZVI induced brominated ethene degradation, assuming a dominant reductive β-elimination pathway via bromoacetylene and acetylene production, simulated organic compound concentrations corresponded well with both batch and large-scale column experimental data. Changes of inorganic reactants were also well captured by the simulations. The similar ZVI induced degradation pathway of TriBE and TCE suggests that outcomes from research on ZVI induced TCE remediation could also be applied to TriBE remediation.  相似文献   
63.
Twenty-four hour PM2.5 samples from a rural site, an urban site, and a suburban site (next to a major highway) in the metropolitan Atlanta area in December 2003 and June 2004 were analyzed for 19 polycyclic aromatic hydrocarbons (PAH). Extraction of the air samples was conducted using an accelerated solvent extraction method followed by isotope dilution gas chromatography/mass spectrometry determination. Distinct seasonal variations were observed in total PAH concentration (i.e. significantly higher concentrations in December than in June). Mean concentrations for total particulate PAHs in December were 3.16, 4.13, and 3.40 ng m?3 for the urban, suburban and rural sites, respectively, compared with 0.60, 0.74, and 0.24 ng m?3 in June. Overall, the suburban site, which is impacted by a nearby major highway, had higher PAH concentration than did the urban site. Total PAH concentrations were found to be well correlated with PM2.5, organic carbon (OC), and elemental carbon (EC) in both months (r2 = 0.36–0.78, p < 0.05), although the slopes from the two months were different. PAHs represented on average 0.006% of total PM2.5 mass and 0.017% of OC in June, compared with 0.033% of total PM2.5 and 0.14% of OC in December. Total PAH concentrations were also correlated with potassium ion (r2 = 0.39, p = 0.014) in December, but not in June, suggesting that in winter biomass burning can potentially be an important source for particulate PAH. Retene was found at a higher median air concentration at the rural site than at the urban and suburban sites—unlike the rest of the PAHs, which were found at lower levels at the rural site. Retene also had a larger seasonal difference and had the weakest correlation with the rest of the PAHs measured, suggesting that retene, in particular, might be associated with biomass burning.  相似文献   
64.
Paleoecological reconstructions of forest stand histories for two upland watersheds at Acadia National Park in Maine were completed to support related watershed chemistry studies. The project hypothesis was that forest type and fire history influence long-term cycling and storage of atmospheric mercury and nitrogen within watersheds. The reconstructions document differences in major vegetation composition and disturbance between the burned and unburned watersheds during the past several centuries. Pollen and charcoal stratigraphies from organic sediment accumulations in forested wet depressions indicate that the present experimental design of contrasting disturbance and forest histories has persisted during recent centuries. The unburned watershed has been dominated by spruce (Picea rubens) and fir (Abies balsamea) for 500 years or more and has not recently burned or been substantially cleared. The burned watershed is dominated by a heterogeneous forest of patchy hardwood, mixed wood, and softwood stands. A large portion of this watershed burned severely in 1947 and probably more than once in the 1800s, and has supported heterogeneous successional forests for 200 years or longer. Overall, these results support the underlying premise that the experimental design of this watershed research can be used to infer landscape controls on biogeochemical processes.  相似文献   
65.
Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and organochlorine pesticides were measured in the serum of a sample of the New Zealand population aged 15 years and older. This was the first study to obtain representative measures of PCDDs, PCDFs and PCBs in the adult population of an entire country. Serum samples were obtained in 1996-1997. Potentially occupationally exposed individuals were excluded. Serum samples were pooled according to stratification criteria for area of residence, ethnicity, age, and sex. Of the 80 possible strata, sufficient serum for chemical analysis was available for 60, to which 1,834 individual samples contributed. For the PCDDs and PCDFs, most 2,3,7,8-chlorinated congeners were measured in all strata, with a mean toxic equivalents concentration across all strata of 12.8 ng TEQ kg(-1) lipid. Seven PCB congeners were frequently measured, including the coplanar congeners #126 and #169, quantified in all strata. Of the pesticides and their metabolites, only beta-HCH, dieldrin and pp'-DDE were consistently detected across strata. There was a general trend of increasing concentration with age. There were no consistent differences between the sexes, or between people of Maori (the indigenous people of New Zealand) and non-Maori ethnicity. Concentrations of PCDDs and PCDFs tended to increase in a North-South direction, possibly reflecting greater levels of industrialization and population concentration, and concentrations of the pesticide products were highest in the South, possibly reflecting historical use patterns. Results were consistent with a recent study of concentrations of these compounds in the milk of first-time mothers.  相似文献   
66.
This article proposed and tested a multilevel and interactional model of individual innovation in which weekly moods represent a core construct between context, personality, and innovative work behavior. Adopting the circumplex model of affect, innovative work behavior is proposed as resulting from weekly positive and high‐activated mood. Furthermore, drawing on the Big Five model of personality and cognitive appraisal theory, openness to experience and support for innovation are proposed as individual and contextual variables, respectively, which interplay in this process. Openness to experience interacts with support for innovation leading to high‐activated positive mood. Furthermore, openness interacts with these feelings leading to greater levels of innovative work behavior. Overall, the model entails a moderated mediation process where weekly high‐activated positive mood represents a crucial variable for transforming contextual and individual resources into innovative outcomes. These propositions were tested and supported using a diary methodology and multilevel structural equation modeling, on the basis of 893 observations of innovative work behavior and moods nested in 10 weekly waves of data. This information was collected from 92 individuals of diverse occupations employed in 73 distinct companies. Theoretical and practical implications are discussed. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
67.
Ecological economics is a field of enquiry that has had, with a few exceptions, an almost entirely terrestrial focus. Given the fundamental ecological and economic importance of oceanic and coastal ecosystems, and the accelerating deterioration of these ecosystems, we argue that there is an urgent case to redress this imbalance. In so doing, the scope of ecological economics will be extended and compelling insights developed and applied to better understand and govern marine systems. Although we acknowledge that there is no unequivocal or unitary view of what might constitute an ecological economics of the oceans and coasts, we assert that it should consist of at least ‘four cornerstones’: (1) sustainability as the normative goal; (2) an approach that sees the socio-economic system as a sub-system of the global ecological system; (3) a complex systems approach; and (4) transdisciplinarity and methodological pluralism. Using these four cornerstones, we identify a future research agenda for an ecological economics of the oceans and coasts. Specifically, we conclude that ecological economists must work with other disciplines, especially those involved in marine policy and practice, to move from a ‘frontier economics’ (which has dominated marine management) to entrench an ‘ecological economics’ of the oceans and coasts as the dominant paradigm.  相似文献   
68.
Quality assurance (QA) and quality control (QC) are basic components of a TQEM program. All too often these functions are loosely defined and used interchangeably. Yet, the quality of outputs and services strongly depends on the caliber of the communications between the “customer” and the “supplier.” A clear understanding of customer needs and expectations is essential to selecting and applying suitable QA and QC. Planning, implementing, and assessing all play a major part in the quality of final outputs. A clear understanding of the customer/supplier relationship and the functional roles played by each is essential to a successful TQEM program. This article identifies, clarifies, and simplifies the quality management responsibilities of the customer and the supplier. The ideas presented are applicable in all work environments, including research and development (R&D).  相似文献   
69.
ABSTRACT: The application of a water balance model in finding “solutions” to the supply/demand problem was demonstrated using the South Platte River basin as a case study. Solutions were ascertained by hand, using both “average” and “stress” supply/demand conditions, and were developed for 1980, 2000, and 2020; nonquantifiable boundary conditions were incorporated by judgement. The solution obtained for a particular set of conditions is not unique and has strong normative characteristics; thus it must be judged by various interest groups having different ethical positions. The water balance model has a tabular display format and so the “model” is merely a simple table, i.e., a “water balance table.” In this work the water balance table was displayed on an eight-foot by eight-foot color-coded magnetic board. The board provides a means to both find and display the needed supply/demand “solution.” The tabular display facilitates understanding of the systemwide solution and the formulation of value judgments. Based upon these value judgments and an initial “straw man” solution, successive negotiated solutions can be found which can minimize “conflict.”  相似文献   
70.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号