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   254篇
  免费   1篇
  国内免费   5篇
安全科学   4篇
废物处理   23篇
环保管理   6篇
综合类   40篇
基础理论   68篇
污染及防治   95篇
评价与监测   16篇
社会与环境   8篇
  2023年   3篇
  2022年   3篇
  2020年   2篇
  2019年   1篇
  2018年   2篇
  2017年   5篇
  2016年   2篇
  2015年   9篇
  2014年   9篇
  2013年   9篇
  2012年   9篇
  2011年   14篇
  2010年   12篇
  2009年   14篇
  2008年   10篇
  2007年   27篇
  2006年   18篇
  2005年   6篇
  2004年   13篇
  2003年   7篇
  2002年   12篇
  2001年   14篇
  2000年   9篇
  1999年   3篇
  1998年   5篇
  1997年   4篇
  1994年   5篇
  1993年   1篇
  1990年   1篇
  1989年   1篇
  1988年   4篇
  1985年   3篇
  1984年   1篇
  1981年   1篇
  1980年   2篇
  1979年   2篇
  1978年   1篇
  1977年   2篇
  1976年   3篇
  1971年   1篇
  1969年   1篇
  1967年   1篇
  1966年   1篇
  1965年   1篇
  1963年   1篇
  1958年   2篇
  1957年   1篇
  1955年   1篇
  1954年   1篇
排序方式: 共有260条查询结果,搜索用时 0 毫秒
101.
102.
103.
Chorionic villus samples from a healthy pregnant female were obtained for first-trimester prenatal diagnosis. A translocation trisomy 21 was diagnosed. A consecutive amniocentesis revealed a normal male karyotype. At term a healthy boy was born. Cytogenetic analysis from cord blood showed a regular karyotype of 46,XY, whereas in term placenta a pathological karyotype of 47,XY,+mar was found.  相似文献   
104.
There are different methods to estimate and predict effects of chemical elements and corresponding speciation forms in biochemistry and toxicology, including statements on essentiality and antagonisms. Two approaches are given here: (1) "identity cards" describing biologically fundamental aspects of element chemistry and (2) qualitative discussions which assume the existence of (indirect ways into) chemical autocatalysis to be essential for maintaining life and permitting reproduction. The latter method, developed by the present authors, draws upon Stoichiometric Network Analysis, a safe procedure for complexity reduction in feedback networks) and provides estimates of concentration regimes for different elements suitable for survival and reproduction. The biochemical hierarchy level considered here is that of (metallo-)proteins. Thermodynamic toxicity aspects are given in correlations with DMSO solvent affinities and thiocyanate bonding modes. Effects of antagonists and of ion substitution within metalloenzymes or of metabolic simplification can be dealt with, likewise increased sensitivities within symbiotic relationships and within carcinomas are explained which are relevant for environmental monitoring and tumour therapy, respectively.  相似文献   
105.
BACKGROUND, AIM AND SCOPE: For decades, very large areas of former military sites have been contaminated diffusely with the persistent nitroaromatic explosive 2,4,6-trinitrotoluene (TNT). The recalcitrance of the environmental hazard TNT is to a great extent due to its particulate soil existence, which leads to slow but continuous leaching processes. Although improper handling during the manufacture of TNT seems to be a problem of the past in developed countries, environmental deposition of TNT and other explosives is still going on unfortunately, resulting from thousands of unexploded ordnance or low order explosions at munitions test areas and at current battlefields. OBJECTIVE: Sustainable phytoremediation strategies for explosives in Germany, which intend to use trees to decontaminate soil and groundwater ('dendroremediation'), have to consider that most of the former German military sites are already covered with woodlands, mainly with conifer stands. Therefore, parallel investigation of the remediation potential is necessary for both of the selected hybrids of fast growing broadleaf trees, which are waiting for planting and forest conifers, which have already proven for decades that they are able to grow on explosive contaminated sites. MAIN FEATURES: A short literature review is given regarding phytoremediation of TNT with herbaceous plants and some general aspects of dendroremediation are discussed. Furthermore, an overview of our TNT-dendroremediation research network is introduced, which has the strategic goal to make dendroremediation more calculable for a series of potent trees for site-adapted in situ application and for the assessment of tree remediation potentials in natural attenuation processes. RESULTS AND DISCUSSION: Some of our methods, results and conclusions yet unpublished are presented. For a preliminary calculation of area-related annual TNT dendroremediation potential of five-year-old trees, the following values were assessed: Salix EW-13 6.0, Salix EW-20 8.5, Populus ZP-007 4.2, Betula pendula 5.2, Picea abies 1.9 and Pinus sylvestris 0.8 g m(-2) a(-1). For a 45-year-old spruce forest, an annual natural attenuation potential of 4.2 g TNT m(-2) a(-1) was found. CONCLUSION, RECOMMENDATIONS AND PERSPECTIVE: Our main results deliver quantitative proposals for dendroremediation strategies in situ and provide decision aids. Also aspects of growth of raw materials for energy production are considered. Our dendroremediation research concept for TNT and its congeners can be easily completed for other trees of interest and it can also be applied to herbaceous plants. Knowing the current bottlenecks of phytoremediation and considering the known environmental behaviour of other contaminants, elements of our methodological approach may be easily adapted to those pollutant groups, e.g. for pesticides, pharmaceuticals, PAHs, chlorinated recalcitrants and, with some restrictions, to inorganics and to multiple contaminations. Our dynamical dendrotolerance test systems will help to predict tree growth on polluted areas. To provide some light into the black box of TNT dendroremediation, experimental data regarding the uptake, distribution and degradation of [14C]-TNT in mature tree tissues will be reported in the second part of this publication.  相似文献   
106.
The grey top-shell, Gibbula cineraria is a common member of temperate to cold water kelp forest communities, but its longevity and the age structure of its populations remains unresolved. Combined measurements of shell growth rates (sclerochronology) and oxygen isotope composition allow analysis of rate and timing of shell growth. Eight specimens were analyzed from the southern North Sea (near Helgoland, German Bight). Three age groups were identified but external measurements (width, height, ornamentation patterns and number of whorls) and shell weight are not adequate for ontogenetic age discrimination. Stable oxygen isotope data is consistent with shell growth during the interval from April to December in isotopic equilibrium with seawater, and growth increments exhibit strong tidal controls with fortnightly bundles well preserved. Reliable environmental proxy data (water temperature) can be extracted from the shell aragonite using conventional stable oxygen isotope analyses, with a temporal resolution of days attainable during intervals of maximum growth, but annual extremes are not always recorded in the shell. While demonstrating the utility of G. cineraria as a environmental and potential paleoenvironmental proxy for kelp forest habitats, its longevity has been significantly overestimated.  相似文献   
107.
Hepatitis E virus (HEV) is a zoonotic agent, which is mainly transmitted by consumption of undercooked meat products originating from infected animals. Domestic pigs and wild boars are the major animal reservoirs, but HEV infections have been also repeatedly described in wild deer species. However, farmed deer has been only sparsely investigated so far. Here, 108 blood and 106 liver samples from fallow deer, red deer, and sika deer strictly hold in game enclosures from 11 farms in Germany were analyzed for markers of HEV infection. Using a commercial double antigen sandwich ELISA, 3/108 (2.7%) serum samples were scored borderline for HEV-specific antibodies, whereas the remaining samples were negative. No HEV-RNA (0%) was detected in the 106 liver samples. The results suggest a low risk of HEV infection in farmed deer in Germany.  相似文献   
108.
BACKGROUND, AIM AND SCOPE: Tests during the last few years have confirmed that 4-nonylphenol (4-NP) can have oestrogen-like effects (xeno-hormone) on animal organisms. The objective was to firstly evaluate the ecotoxicological effects of 4-NP on plants such as hydrocultures. To clarify how this substance interferes with the photosynthetic system of plants, various tests were carried out using the basil plant (Ocimum basilicum). METHODS: The effect of the pollutant 4-NP on the pigment content in the leaves of the basil plant was analysed with the use of High-Performance-Liquid-Chromatography (HPLC). RESULTS AND DISCUSSION: A general assessment of the HPLC data revealed that plants that came in contact with the 4-nonylphenol showed a change in pigmentation. More chlorophyll a and b was produced, although at the same time a higher production of degradation products and by-products of the chlorophylls was observed. These occurrences can therefore be seen as an impairment of the photosynthetic process. The contaminated plants produced less xanthophylls than the non-contaminated ones, though these differences were statistically not significant. CONCLUSION AND PERSPECTIVE: The variations on the pigment content in the leaves of the basil plant can be interpreted as a consequence of the 4-NP application. It was, however, not investigated whether the plants absorbed the pollutants directly. The effect could have been caused by adsorption of the oily substance to the roots, and this could have led to a hindrance of the uptake of nutrients and possibly water. In order to clarify this further, biochemical experiments are being conducted.  相似文献   
109.
New concepts in product use for sustainable consumption   总被引:3,自引:0,他引:3  
The paper presents the main results of a recent study on sustainable use of products. It reveals that strategies of use intensification and useful life extension are environmentally beneficial. Moreover, analysis of household washing and winter sports illustrated that successful implementation of sustainable use patterns occurs as a shift of use regimes. Such regimes are the result of a complex interplay of supply and demand side factors, relationship among actors, technical trajectories, organisational structures etc. One decisive factor is the presence of strategic players, so called “change agents”. In addition, four user types have been identified in a representative survey (“ownership-oriented”, “open-minded”, “consumption-oriented”, “low interest”) to which use intensification and useful life extension can be targeted.  相似文献   
110.
The relationship among sugar concentrations, microbial community and physical variables (precipitation and soil temperature) was investigated in a ryegrass soil from January 2004 to January 2005. Mono- and disaccharide sugars were extracted using a mixture of dichloromethane and methanol and analyzed as their TMS derivatives by GC-MS. Changes in microbial community were assessed using phospholipid and neutral lipid fatty acids (PLFA and NLFA, respectively) analysis. The results of a one-year study showed that the seasonal variability of sugar contents found in the soil samples is mainly related to biomass or nutritional status of the fungal community. The increase in sucrose and fructose exudation by plant roots in the beginning of the growing season (early spring) may be responsible for the highest fungal biomass amount (PLFAs) observed in this study. Fungal storage lipid abundances (NLFAs) peaked in summer, during the same period that the highest concentrations of mannitol and trehalose were detected. This is consistent with these two sugars being stress-induced fungal metabolites, produced due to the low soil moisture observed during this season. In contrast, bacterial community growth seems to be more dependent on plant substrate than on physical variables, since the strongest decrease in bacterial biomass amounts (PLFAs) was found after cutting of the ryegrass field in early July.  相似文献   
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