全文获取类型
收费全文 | 1098篇 |
免费 | 201篇 |
国内免费 | 598篇 |
专业分类
安全科学 | 76篇 |
废物处理 | 71篇 |
环保管理 | 64篇 |
综合类 | 1032篇 |
基础理论 | 337篇 |
污染及防治 | 244篇 |
评价与监测 | 57篇 |
社会与环境 | 12篇 |
灾害及防治 | 4篇 |
出版年
2023年 | 19篇 |
2022年 | 51篇 |
2021年 | 76篇 |
2020年 | 41篇 |
2019年 | 61篇 |
2018年 | 127篇 |
2017年 | 60篇 |
2016年 | 70篇 |
2015年 | 60篇 |
2014年 | 71篇 |
2013年 | 122篇 |
2012年 | 107篇 |
2011年 | 123篇 |
2010年 | 81篇 |
2009年 | 101篇 |
2008年 | 77篇 |
2007年 | 89篇 |
2006年 | 73篇 |
2005年 | 63篇 |
2004年 | 58篇 |
2003年 | 68篇 |
2002年 | 45篇 |
2001年 | 42篇 |
2000年 | 45篇 |
1999年 | 31篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 20篇 |
1995年 | 25篇 |
1994年 | 9篇 |
1993年 | 16篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1897条查询结果,搜索用时 17 毫秒
861.
Qingqing Li Chao Lv Xiangwei Xia Chao Peng Yan Yang Feng Guo Jianfeng Zhang 《Frontiers of Environmental Science & Engineering》2022,16(11):138
862.
Cr(VI)-based compounds pollution have attracted global concern due to serious harm to humans and environment. Hence, it is crucial to exploit an effective technique to eliminate Cr(VI) in water. Herein, we in-situ grown BiOI on graphitic carbon nitride to prepare the BiOI/g-C3N4 (BCN) direct Z-scheme heterojunction by solid phase engineering method at room temperature. Experimental result shown the photocatalytic activity of pure BiOI were obviously enhanced by constructing Z-scheme BCN heterostructure, and BCN-3 heterostructure exhibited the optimal photocatalytic degradation of RhB with 98%yield for 2.5 h and reduction of Cr(VI) with more than 99%yield for 1.5 h at pH=2. Stability test shows BCN-3 still kept more than 98%reduction efficiency after 6 cycles. In addition, we also studied the reduction mechanism that shown the ·O2-radicals essentially helped to reduce the Cr(VI) in aqueous solution under illumination, verified the direct Z-scheme charge transfer path by X-ray photoelectron spectroscopy (XPS) and the free radical trapping experiment. The work open a new way for rationally designing photo-catalyst heterostructure to reduce Cr(VI) to Cr(III). 相似文献
863.
Fe~0体系降解2,4二氯酚的影响因素及其反应机理 总被引:1,自引:0,他引:1
采用铁屑、炉渣及河砂混合介质降解2,4-二氯酚(2,4-DCP)模拟废水,研究铁屑粒径、铁屑投加量、铁屑与炉渣配比、pH值等因素对2,4-DCP脱氯效果的影响,探讨Fe0体系降解2,4-DCP的反应机理。结果表明,铁屑粒径、铁屑投加量、铁屑与炉渣配比、pH对2,4-DCP脱氯效果均有显著影响,在铁屑粒径为2~5 mm、不改变废水pH、铁屑与炉渣质量比为31∶9条件下,Fe0体系对2,4-DCP去除率高达97%。2,4-DCP经脱氯后主要产物为2-氯酚、4-氯酚和苯酚,反应后废水的可生化性明显提高,利于后续的生物处理。 相似文献
864.
中小企业“4+1”安全管理与监管模式研究 总被引:7,自引:5,他引:2
在对全国中小企业安全生产状况调查的基础上,分析了中小企业的安全生产现状其数量多、绝大多数在乡镇街道、生产安全事故多发、职业病危害严重、从业人员素质低、生产力水平低;政府针对中小企业的安全监管人员数量少;乡镇街道的安全生产中介服务机构数量少,服务内容单一。因此,提出了中小企业安全生产监督管理“4+1”模式,其中“4”是指中小企业、政府安全监管部门、中介机构和社会监督部门的安全生产管理、监管、服务、监督体系,“1”是指提高监管效能的运行保障机制。该模式从宏观上为政府监管中小企业提出了一种新的思路,从微观上为中小企业、政府安全监管部门、中介服务机构、社会监督部门的安全生产工作提出了新的方法。 相似文献
865.
Final disposal of high-level radioactive waste in deep repositories located in fractured granite formations is being considered by several countries. The assessment of the safety of such repositories requires using numerical models of groundwater flow, solute transport and chemical processes. These models are being developed from data and knowledge gained from in situ experiments such as the Redox Zone Experiment carried out at the underground laboratory of Äspö in Sweden. This experiment aimed at evaluating the effects of the construction of the access tunnel on the hydrogeological and hydrochemical conditions of a fracture zone intersected by the tunnel. Most chemical species showed dilution trends except for bicarbonate and sulphate which unexpectedly increased with time. Molinero and Samper [Molinero, J. and Samper, J. Groundwater flow and solute transport in fracture zones: an improved model for a large-scale field experiment at Äspö (Sweden). J. Hydraul. Res., 42, Extra Issue, 157–172] presented a two-dimensional water flow and solute transport finite element model which reproduced measured drawdowns and dilution curves of conservative species. Here we extend their model by using a reactive transport which accounts for aqueous complexation, acid–base, redox processes, dissolution–precipitation of calcite, quartz, hematite and pyrite, and cation exchange between Na+ and Ca2+. The model provides field-scale estimates of cation exchange capacity of the fracture zone and redox potential of groundwater recharge. It serves also to identify the mineral phases controlling the solubility of iron. In addition, the model is useful to test the relevance of several geochemical processes. Model results rule out calcite dissolution as the process causing the increase in bicarbonate concentration and reject the following possible sources of sulphate: (1) pyrite dissolution, (2) leaching of alkaline sulphate-rich waters from a nearby rock landfill and (3) dissolution of iron monosulphides contained in Baltic seafloor sediments. Based on these results, microbially mediated processes are postulated as the most likely hypothesis to explain the measured increase of dissolved bicarbonates and sulphates after tunnel construction. 相似文献
866.
Depth profiles of the specific activities of (14)C and carbon isotopic compositions (Delta(14)C, delta(13)C) in soil organic matter and soil CO(2) in a Japanese larch forest were determined. For investigating the transport of CO(2) in soil, specific activities of (14)C, Delta(14)C and delta(13)C in the organic layer, and atmospheric CO(2) in the same forest area were also determined. The specific activity of (14)C and Delta(14)C in the soil organic matter decreased with the increase in depth of 0-60cm, while that of soil CO(2) did not vary greatly at a soil depth of 13-73cm and was more prevalent than that of atmospheric CO(2). Peaks of specific activities of (14)C appeared at the depth of 0-4cm and Delta(14)C values were positive in the depth range from 0 to 15cm. These results suggest that the present soil at a depth of 0-4cm had been produced from the mid-1950s up until 1963, and the bomb C had reached the depth of 15cm in the objective soil area. The delta(13)C in the soil organic matter increased at the depth of 0-55cm, while that of soil CO(2) collected on 8 November 2004 decreased rapidly at the depth of 0-13cm and only slightly at the depth of 53-73cm. By combining the Delta(14)C and delta(13)C of the respective components and using the Keeling plot approach it was made clear that the entering of atmospheric CO(2) showed a large contribution to soil CO(2) at the depth of 0-13cm and a negligible contribution at the depth of 53-73cm for soil air collected on 8 November 2004. Respiration of live roots was presumed to be the main source of soil CO(2) at the depth of 53-73cm on 8 November 2004. 相似文献
867.
Introduced to Saskatchewan in the 1930s as a potential shelterbelt species, European buckthorn is now a prominent understory
shrub in riparian woodland and shrub communities around Saskatoon. Locally, the Meewasin Valley Authority (MVA) is actively
controlling buckthorn as part of its mandate to conserve natural heritage resources of the South Saskatchewan River Valley,
with the goal of restoring the natural biodiversity of remnant patches of native vegetation. European buckthorn is normally
dioecious, and MVA has chosen to treat only fruiting stems in an attempt to limit seed production. Two control techniques
have been used. In one treatment, glyphosate was applied to stems after cutting; alternatively Garlon 4 Dow AgroSciences herbicide
(active ingredient triclopyr) was applied as a chemical girdle directly to the stems using a streamline basal bark spray method.
To date, more than 347,000 fruiting stems of buckthorn have been treated. Results indicate good initial progress in limiting
seed production in dense buckthorn sites, but at a high cost. Although seed eradication is not a practical short-term goal
for the Saskatoon buckthorn population, chemical girdling can substantially and strategically reduce seed and effectively
limit spread. Field-tested strategies to reduce costs and improve efficiencies are discussed. 相似文献
868.
Jensen TS Jensen JD Hasler B Illerup JB Andersen FM 《Journal of environmental management》2007,82(1):133-143
Integrated modelling of the interaction between environmental pressure and economic development is a useful tool to evaluate environmental consequences of policy initiatives. However, the usefulness of such models is often restricted by the fact that these models only include a limited set of environmental impacts, which are often energy-related emissions. In order to evaluate the development in the overall environmental pressure correctly, these model systems must be extended. In this article an integrated macroeconomic model system of the Danish economy with environmental modules of energy related emissions is extended to include the agricultural contribution to climate change and acidification. Next to the energy sector, the agricultural sector is the most important contributor to these environmental themes and subsequently the extended model complex calculates more than 99% of the contribution to both climate change and acidification. Environmental sub-models are developed for agriculture-related emissions of CH(4), N(2)O and NH(3). Agricultural emission sources related to the production specific activity variables are mapped and emission dependent parameters are identified in order to calculate emission coefficients. The emission coefficients are linked to the economic activity variables of the Danish agricultural production. The model system is demonstrated by projections of agriculture-related emissions in Denmark under two alternative sets of assumptions: a baseline projection of the general economic development and a policy scenario for changes in the husbandry sector within the agricultural sector. 相似文献
869.
This paper examines whether corporate financial performance is affected by public endorsement of environmental and social performance. Event study methodology, which relies on the notion of market efficiency, is used to examine the relationship between positive and negative announcements and changes in share prices or daily returns. Inclusion in and deletion from the FTSE4Good UK Index is used as a proxy measure for good (poor) corporate social responsibility. The abnormal or unexpected daily returns associated with an event are calculated and their significance tested. The results show a trend towards positive and negative announcements having the expected effects on daily returns. But these movements are not significant and the data do not suggest that a firm's presence on the index brings it any significant financial return for signalling its corporate social responsibility. 相似文献
870.
Effect of feeding time on the performance of a sequencing batch reactor treating a mixture of 4-CP and 2,4-DCP 总被引:1,自引:0,他引:1
This paper investigated the biodegradation kinetics of 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) separately in batch reactors and mixed in sequencing batch reactors (SBRs). Batch reactor experiments showed that both 4-CP and 2,4-DCP began to inhibit their own degradation at 53 and 25 mg l(-1), respectively, and that the Haldane equation gave a good fit to the experimental data because r(2) values were higher than 0.98. The maximum specific degradation rates (q(m)) were 130.3 and 112.4 mg g(-1) h for 4-CP and 2,4-DCP, respectively. The values of the half saturation (K(s)) and self-inhibition constants (K(i)) were 34.98 and 79.74 mg l(-1) for 4-CP, and 13.77 and 44.46 mg l(-1) for 2,4-DCP, respectively. The SBR was fed with a mixture of 220 mg l(-1) of 4-CP, 110 mg l(-1) of 2,4-DCP, and 300 mg l(-1) of peptone as biogenic substrate at varying feeding periods (0-8h) to evaluate the effect of feeding time on the performance of the SBR. During SBR operation, in addition to self-inhibition, 4-CP degradation was strongly and competitively inhibited by 2,4-DCP. The inhibitory effects were particularly pronounced during short feeding periods because of higher chlorophenol peak concentrations in the reactor. The competitive inhibition constant (K(ii)) of 2,4-DCP on 4-CP degradation was 0.17 mg l(-1) when the reactor was fed instantaneously (0 h feeding). During longer feedings, increased removal/loading rates led to lower chlorophenol peak concentrations at the end of feeding. Therefore, in multi-substrate systems feeding time plus reaction time should be determined based on both degradation kinetics and substrate interaction. During degradation, the meta cleavage of 4-chlorocatechol resulted in accumulation of a yellowish color because of the formation of 5-chloro-2-hydroxymuconic semialdehyde (CHMS), which was further metabolized. Isolation and enrichment of the chlorophenols-degrading culture suggested Pseudomonas sp. and Pseudomonas stutzeri to be the dominant species. 相似文献