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521.
在对多态系统可靠性研究的基础上,将基于矩阵分析的多态系统可靠性分析方法用于区域地质灾害的危险性评价研究,结果表明该方法能较好地定量评价区域地质灾害的危险程度.利用多态系统的可靠性分析方法进行地质灾害危险性区划,不仅可以得出各子区域所处的主要危险区和次主要危险区,而且还可以得出各子区域处于不同地质灾害危险区的可靠度(即可能性大小).该方法基本克服了目前危险性评价方法中评价指标分级和量化以及危险性程度分级的人为性和随意性,具有分级标准统一、评价因素和评价方法相对简单、不受区域条件限制、适用性强等特点. 相似文献
522.
饮用水中微量有机物的污染是关系饮用水生态安全的重要问题。以饮用水中微量的内分泌干扰类除草剂阿特拉津为研究对象,分别采用微生物降解技术和光催化氧化技术对其进行降解,考察温度对阿特拉津降解效果的影响。研究结果表明:阿特拉津浓度为1 mg/L时,3种温度条件下,除锰功能菌MB4对阿特拉津均有明显的去除效果,降解时间为7 d时,阿特拉津的去除率达到65%。底物浓度为200 μg/L,3种温度条件下,活性炭负载二氧化钛(TiO2/PAC)催化剂光降解阿特拉津30 min时,其去除率均达到90%。光催化氧化技术协同微生物降解技术在饮用水中微量的内分泌干扰物的去除中有广阔的应用前景。 相似文献
523.
孔繁德 《中国环境管理干部学院学报》2010,20(3):1-4
曲格平撰写的《生态文明理念和发展方略》重点阐述了生态文明的重要性,深刻揭示了生态文明的必然性,提出了中国生态文明建设的路径和发展方略,启示我们要更加深刻地认识生态文明的重要现实意义和历史必然性,进一步提高贯彻落实科学发展观的自觉性,努力开辟具有中国特色的人与自然和谐发展的道路,开创环保工作的"战略反攻"的新阶段,积极发展环境科技,培养大批高素质环保科技人才。 相似文献
524.
A regression method was developed for the hydrophobicity ruler approach, which is an indirect method for determining the octanol/water partition coefficients of very hydrophobic compounds. Two constants introduced into the mathematical model were obtained by regression of the absorption data sampled before the partition equilibrium. A water miscible organic solvent was used to increase the solubility of the very hydrophobic compounds in the aqueous solution so that the hydrophobicity scale was reduced and the equilibration was accelerated. Polydimethylsiloxane/methanol aqueous solution and a series of 21 polychlorinated biphenyls (PCBs) were used to demonstrate the regression method. The PCB compounds with known experimental logK(o/w) values served as reference compounds, while the PCB compounds without known logK(o/w) values were determined. The distribution coefficients (logK(p/s)), uptake and elimination rate constants were obtained from the two regression constants for each compound (reference or unknown). The correlation of the logK(p/s) values of the reference PCB compounds with their logK(o/w) values was linear (logK(o/w)=2.69logK(p/s)+0.76, R(2)=0.97). The logK(o/w) values were compared with literature values and suggested that some values from the literature far off the calibration line could be inaccurate. The critical experimental factors, the merits of the regression method were discussed. 相似文献
525.
Kong WD Zhu YG Liang YC Zhang J Smith FA Yang M 《Environmental pollution (Barking, Essex : 1987)》2007,147(1):187-193
A series of experiments were conducted in a hydroponic system to investigate the uptake of oxytetracycline (OTC) and its toxicity to alfalfa (Medicago sativa L.). OTC inhibited alfalfa shoot and root growth by up to 61% and 85%, respectively. The kinetics of OTC uptake could be well described by Michaelis-Menten equation with Vmax of 2.25 micromol g-1 fresh weight h-1, and Km of 0.036 mM. The uptake of OTC by alfalfa was strongly inhibited by the metabolic inhibitor, 2,4-DNP (2,4-dinitrophenol), at pH 3.5 and 6.0, but not by the aquaporin competitors, glycerol and Ag+. OTC uptake, however, was significantly inhibited by Hg2+, suggesting that the inhibition of influx was due to general cellular stress rather than the specific action of Hg2+ on aquaporins. Results from the present study suggested that OTC uptake into alfalfa is an energy-dependent process. 相似文献
526.
Thirteen organochlorine pesticides (OCPs) in 18 fish species from Qiantang River were firstly determined by GC-ECD. To elucidate the sources and the environment fate of these pollutants, water and sediment samples were also analyzed for OCPs contents. Total concentrations of OCPs in fish muscles ranged from 7.43 to 143.79 ng g(-1) wet weight (ww) with highest concentration recorded in sole fish (Cynoglossus abbreviatus), a benthic carnivore. The results indicated that carnivore fish have higher OCPs concentration than other fish with different feeding modes. OCPs concentration in fish was in the range of 1.86-5.85, 2.65-133.51 and 1.94-12.48 ng g(-1) for HCHs (alpha-, beta-, gamma-, delta-HCH), DDTs (p,p'-DDD, p,p'-DDE, p,p'-DDT, o,p'-DDD) and other OCPs (aldrin, diedrin, endrin, heptachlor, heptachlor expoide), respectively. The highest OCPs concentration in fish organs of four big fish species was found in brain of silver carp (Hypophthalmichthys molitrix), 289.26 ng g(-1) ww followed by kidney, liver, heart and gill. Among the OCPs analyzed, DDE, gamma-HCH and heptachlor were the predominant contaminants in fish muscle, which indicated that there was recent input of lindane. Significant correlation was observed between concentrations of DDTs and lipid content as well as between OCPs and lipid contents in fish species. Both field water bioconcentration factors (BCF) and sediment BCF showed a positive correlation with octanol-water partition coefficients (Kow) in the sole fish. 相似文献
527.
Hu Z Navarro R Nomura N Kong H Wijesekara S Matsumura M 《Environmental science and pollution research international》2007,14(1):12-18
Background There has been an increasing concern about the treatment and disposal of contaminated sediment from dredged river, harbor
or estuary due to the accumulated toxic organics such as dioxins and inorganics particularly heavy metals like Cr, Pb, Zn,
Cu, Hg and Cd. However, considering the huge amount of materials and financial costs involved, any candidate technology must
ultimately result to reusable residual by-products. This can only be made possible if the toxic pollutants are removed or
stabilized in the raw sediment and then fed back into the materials cycle. Currently, we are developing a pyrolysis process
for the commercial-scale cleanup of dioxins and heavy metal-contaminated river sediment to yield reusable char for various
economical applications. In this connection, this paper describes our preliminary investigation into the extent of dioxins
and heavy metal volatilization from actual contaminated sediment. The stabilization of certain metallic species particularly
Cr ions was studied.
Methods Laboratory scale pyrolysis experiments were conducted using a special horizontal lab-scale pyrolyzer. Sediment samples from
Shanghai Suzhou Creek and Tagonoura Harbor were pyrolyzed in the reactor under nitrogen gas at 800°C and different retention
times of 30, 60 and 90 min. A constant heating rate of 10°C min-1 was employed. The pyrolysis gas was first allowed to pass
through a cold trap to condense the tar. Uncondensed gases were then channeled through a column containing an adsorbent (XAD-2
Resin) for dioxins. Heavy metal concentrations in the initial and final sediment residues were analyzed by ICP (Nippon Jarrel-Ash)
following their acid and alkali (for Cr6+) digestion. Dioxins content of the pyrolysis char, tar, and exhaust gases in the
dioxin adsorbent were also determined. For comparative purpose, thermal treatment under air flow was conducted.
Results The data for the removal of heavy metals from Suzhou Creek sediment showed very significant reductions in Pb, Zn and Cr6+
content of the sediment at this condition. Percentage removals were 42.4%, 60.8% and 42.2%, respectively. The disappearance
of Cr6+ was due to reduction reactions rather than volatilization since the total Cr content remained almost unchanged. Other
heavy metals such as Cu, Fe and Ni showed very minimal reductions. Nonetheless, Toxicity Characteristics Leaching Procedure
(TCLP) tests confirmed that these residual heavy metals were rather stable in the pyrolysis char. Reduction of toxic Cr6+
at 42.2% has also been achieved by pyrolysis (with N2) as opposed to the more than 580 % increase in Cr6+ observed during
thermal oxidation (with air).
Discussion Pyrolysis also remove toxic organics particularly dioxins from the sediment. For the total dioxins, removal percentage of
99.9999% was achieved even at the lowest retention time of 30 min. Almost all polychlorinated dibenzo-p-dioxine (PCDDs) and
polychlorinated dibenzo-furans (PCDFs) were removed at any retention time. The TEQs detected from the solid residues were
mainly contributed by dioxin-like PCBs, yet these were present in relatively trace quantities. At the shortest retention time
of 30 min, only 0.000085 pg-TEQ g-1 of polychlorinated biphenyls (PCBs) was detected in the pyrolysis char. Furthermore, the
residual PCBs have very low toxicity ratings and none of the highly toxic PCBs, which were initially present in the sediment
such as 3,3',4,4',5-PeCB and 3,3',4,4'5,5'-HxCB, were detected in the char. Results further confirmed that most of the dioxins
that were removed were transferred to the gas phase so that volatilization may be considered as the main mechanism for their
removal.
Conclusion Some heavy metals particularly Pb and Zn can be volatilized under N2 pyrolysis at 800oC. Pyrolysis also prevented the formation
of more toxic Cr6+ ions and at the same time resulted to its reduction by around 42.2% contrast to the 580% increase during
thermal oxidation. PCDDs and PCDFs have been removed and were not formed in the solid products over the retention time range
of 30-90 min at 800°C. Dioxin-like PCBs mostly remained and a retention time of 30 min was found sufficient for its maximum
removal.
Recommendations and Perspective . With the above results, a temperature of 800oC at a retention time of 30 min is sufficient for the removal of total dioxins
and some heavy metals by volatilization. It is however necessary to destroy the dioxins as well as recover heavy metals in
the gas phase. Stability of remaining heavy metals in the char also needs to be confirmed by leaching tests. These are the
major concerns, which we are currently evaluating to establish the feasibility of our proposed large scale pyrolysis system
for sediment treatment. 相似文献
528.
Hong Wang Jay Gao Ruiliang Pu Liliang Ren Yan Kong He Li Ling Li 《Environmental monitoring and assessment》2014,186(7):4013-4028
This study aims to assess the relative importance of natural and anthropogenic variables on the change of the red-crowned crane habitat in the Yellow River Nature Reserve, East China using multitempopral remote sensing and geographic information system. Satellite images were used to detect the change in potential crane habitat, from which suitable crane habitat was determined by excluding fragmented habitat. In this study, a principal component analysis (PCA) with seven variables (channel flow, rainfall, temperature, sediment discharge, number of oil wells, total length of roads, and area of settlements) and linear regression analyses of potential and suitable habitat against the retained principal components were applied to explore the influences of natural and anthropogenic factors on the change of the red-crowned crane habitat. The experimental results indicate that suitable habitat decreased by 5,935 ha despite an increase of 1,409 ha in potential habitat from 1992 to 2008. The area of crane habitat changed caused by natural drivers such as progressive succession, retrogressive succession, and physical fragmentation is almost the same as that caused by anthropogenic forces such as land use change and behavioral fragmentation. The PCA and regression analyses revealed that natural factors (e.g., channel flow, rainfall, temperature, and sediment discharge) play an important role in the crane potential habitat change and human disturbances (e.g., oil wells, roads, and settlements) jointly explain 51.8 % of the variations in suitable habitat area, higher than 48.2 % contributed by natural factors. Thus, it is vital to reduce anthropogenic influences within the reserve in order to reverse the decline in the suitable crane habitat. 相似文献
529.
Pollution of intensively managed greenhouse soils by nutrients and heavy metals in the Yellow River Irrigation Region,Northwest China 总被引:2,自引:0,他引:2
Xiaole Kong Jing Cao Rangyun Tang Shengqiang Zhang Fang Dong 《Environmental monitoring and assessment》2014,186(11):7719-7731
The present study aimed to assess the potential ecological risk of heavy metals and nutrient accumulation in polytunnel greenhouse soils in the Yellow River irrigation region (YRIR), Northwest China, and to identify the potential sources of these heavy metals using principal component analysis. Contents of available nitrogen (AN), phosphorus (AP), and potassium (AK) in the surface polytunnel greenhouse soils (0–20 cm) varied from 13.42 to 486.78, from 39.10 to 566.97, and from 21.64 to 1,156.40 mg kg?1, respectively, as well as AP, soil organic matter (SOM) and AK contents tended to increase significantly at the 0–20- and 20–40-cm soil layers. Heavy metal accumulations occurred in the polytunnel greenhouse soils as compared to arable soils, especially at a depth of 20 cm where Cd, Zn and Cu contents were significantly higher than arable soil. Cd and As were found to be the two main polluting elements in the greenhouse soils because their contents exceeded the thresholds established for greenhouse vegetable production HJ333-2006 in China and the background of Gansu province. It has been shown that Cd, Cu, Pb and Zn at the 0–20-cm soil layer were derived mainly from agricultural production activities, whereas contents of Cr and Ni at the same soil layer were determined by ‘natural’ factors and As originated from natural sources, deposition and irrigation water. 相似文献
530.
Musah Mohammed Kong Yusheng Mensah Isaac Adjei Antwi Stephen Kwadwo Osei Agyemang Andrew Donkor Mary 《Environment, Development and Sustainability》2021,23(10):15225-15239
Environment, Development and Sustainability - This paper explored the link between energy consumption and carbon emissions in North Africa through an Environmental Kuznets Curve (EKC) framework.... 相似文献