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881.
本文运用人类生态学原理,建立了天津城市区生活质量评价的指标体系。基于这一指标体系,采用居民满意度分析方法,剖析了旧城区居民生活质量的主要问题,探讨了天津旧城改造与重建中生活质量调控性规化指标,提出了旧城改造与重建的对策性建议。 相似文献
882.
883.
维护名牌可持续性应坚持针对性、互补性和最佳力度3个原则,以清洁产品和环境标志为重要手段,在生产过程中切实进行清洁生产审计,谋求以资源持续有效利用和环境保护为前提的效益增长。 相似文献
884.
我国核能利用与能源可持续发展探讨 总被引:1,自引:0,他引:1
阐述了我国目前的能源利用状况,火电与核电对环境影响的比较,核废物的处理技术及核电的安全性等,指出大力发展高效清洁的核电是我国实施可持续发展战略的必然要求。 相似文献
885.
886.
水分管理与秸秆施用对稻田CH4和N2O排放的影响 总被引:30,自引:0,他引:30
2000年6~10月在南京近郊江宁区实施大田试验.主要研究了水稻生长季常规灌溉和连续淹水条件下有机质(小麦秸杆)不同施用量(0,2.25,4.5t/hm2)对稻田CH4和N2O排放的影响.结果表明,在连续淹水条件下,CH4排放量与秸杆施用量成正比,N2O排放与秸杆施用量成反比.烤田的N2O的排放量在施用2.25t/hm2秸杆与对照之间无明显差异,但施用4.5t/hm2秸杆处理其N2O的排放量仅为对照或施用2.25t/hm2秸杆处理下的13%左右.综合考虑水稻生长季CH4和N2O排放的全球增温潜势(GWP),在增加有机质的施用量(如按4.5t/hm2施用量秸杆还田)的情况下,烤田的GWP只占连续淹水处理的60%,是减少稻田CH4和N2O综合温室效应的一种有效措施. 相似文献
887.
Wichmann H Sprenger R Ehlers N Bahadir MA 《Environmental science and pollution research international》2005,12(4):227-232
Background, Aims and Scope Releasing agents, applied in the aluminium diecasting process, usually consist of water, oils, waxes, polysiloxanes, as well
as of a set of additives like emulsifiers, corrosion inhibitors, and biocides. During spray application and part release,
gases and aerosols are emitted into workplace air. The chemical compositions of these emissions are determined by the components
of the releasing agents and their reaction products formed during thermal stress of more than 700 °C. In the frame of the
joint project, the analytical tasks were to develop an appropriate sampling strategy for this production environment, to draw
conclusions about the occurrence of hazardous chemicals from production plant studies and from laboratory-scale thermolysis
experiments, and to determine the biodegradability of customary releasing agents.
Methods During realistic test production, active air sampling was performed in a production hall using different adsorption materials.
Cotton fabric sheets were positioned in the production area as passive samplers. Thermolysis experiments were performed at
600 °C with sealed quartz ampoules. The biodegradability of different releasing agents was determined according to German
industry standard DIN 51828 (2000). For analyses, GC/MS (headspace), FTIR, HPLC, IC, and ICP-OES techniques were applied.
Results and Discussion The substance spectrum, which was found in workplace air, was dominated by saturated and non-saturated aliphatic hydrocarbons.
Besides these, alcohols, alkyl phenols, xylenes and other benzene derivatives, aldehydes, glycols, carboxylic acid esters,
and amides were present. The German limiting value of 40 mg/m3 of complex hydrocarbon mixtures in a diecasting workplace atmosphere
was clearly under-run. Total hydrocarbon contents ranged between 2.7 and 6.3 mg/m3. Five different PAH were found in the air
close to the diecasting machine, with maximum concentrations between 0.05 and 3.06 μg/m3. Concentrations of nonylphenols ranged
from 10 to 200 μg/m3, and those of triethanolamine from 20 to 30 μg/m3. From 17 elements analyzed, only B, Fe, P, S, Si, and
Ti were emitted in small amounts. It was striking that the PAH patterns resulting from thermolysis experiments were quite
the same compared to those determined during the diecasting process. An influence of water and of Fe/Al on the composition
of the thermolysis products could mostly be shown. The degrees of biodegradation of three releasing agent extracts after 21
days were 21%, 29%, and 55%, respectively.
Conclusion A sampling strategy was developed, which allows an emission assessment for the industrial process of aluminium diecasting.
It enabled one to control limiting values, to characterise a wide variety of compounds emitted, and to identify and quantify
relevant pollutants. Only a few hazardous substances could be detected during the exemplary use of one releasing agent within
the compounds emitted into workplace air. Indications were found, that the prediction of the formation of harmful substances
from releasing agent components should be possible via thermolysis experiments. The biodegradability test can serve to assess
the expenditure of disposal of the usual leakage run-off of excess agent during production.
Recommendation and Outlook Investigations on further differently composed releasing agents, e.g. powders, would be desirable. A substitution of nonylphenol
ethoxylates by less harmful components would surely be an improvement of a releasing agent with regard to work safety and
health care, because of avoiding the emission of toxic and endocrine active nonylphenols. The surprisingly wide range of biodegradability
of the investigated releasing agents points to an optimization potential, that has obviously not yet been considered. 相似文献
888.
鱼外渔场海洋生物体内重金属和多环芳烃含量水平与食用风险评价 总被引:2,自引:0,他引:2
本文对2018年2月采自东海鱼外渔场的海洋生物(包括鱼类、头足类和甲壳类)体内的5种重金属(Cu、Pb、Cr、As、Cd)和16种多环芳烃(PAHs)的残留水平进行了测定,分析了污染物在生物体内的累积特性并计算了潜在的食用风险,并结合氮稳定同位素技术,初步探讨了生物体内重金属和PAHs的营养级传递特性。结果表明:5种重金属在生物中的平均浓度表现为CuPbCrAsCd;参照我国《食品中污染物限量》和《无公害食品水产品中有毒有害物质限量》,重金属Cu、Cd和Cr均未超过食用标准,但Pb和As的超标现象较为严重。与世界其他范围海域生物体内重金属浓度相比,该渔场生物体内Cu和Pb浓度较高。∑PAHs的平均浓度为283 ng·g~(-1)dw,以低环PAHs(2~3环)占比较大,且主要贡献单体为萘(NAP),总体处于较低污染水平。海洋生物对重金属的富集能力较PAHs高,尤其对Cu的富集最为明显。但风险计算结果表明,重金属和PAHs都不会对消费者的人体健康产生明显风险。重金属Cu和Cd浓度随营养级的升高出现了稀释现象,但重金属Pb、Cr、As和PAHs的营养传递特性不明显,覆盖完整食物链的污染物营养传递特性有待进一步深入研究。 相似文献
889.
890.
Sperm traits often show extreme variation both between and within species. Between-species variation may often be interpreted
in the context of a sperm competition theory, but within-species variation has remained unexplained. Previous studies on intraspecific
variation in sperm traits have focused on a limited set of variables and may have failed to explain observed variation because
of potential trade-offs between different sperm traits. We report on variation in number, size, motility and longevity of
sperm in the frog Crinia georgiana, a species where sperm competition is common. We found intrapopulation variation in sperm size and motility and interpopulation
variation in relative sperm number and size. When we combined relative sperm number and size into one variable, and motility
and longevity into another, we found significant interpopulation variation in these variables as well. We also detected considerable
intra- and significant interpopulation variation in cumulative sperm quality, a combination of all four sperm traits. Furthermore,
a significant effect of the interaction between population origin and male size on sperm characteristics indicated interpopulation
variation in the strength of selection acting on sperm traits of males adopting different mating strategies. We discuss heterogeneity
in the reproductive environment, a complex genetic background in the determination of sperm characteristics and varying levels
of developmental noise as potential contributors to the observed variation in sperm traits. 相似文献