全文获取类型
收费全文 | 770篇 |
免费 | 32篇 |
国内免费 | 63篇 |
专业分类
安全科学 | 32篇 |
废物处理 | 8篇 |
环保管理 | 111篇 |
综合类 | 413篇 |
基础理论 | 123篇 |
污染及防治 | 108篇 |
评价与监测 | 40篇 |
社会与环境 | 13篇 |
灾害及防治 | 17篇 |
出版年
2023年 | 8篇 |
2022年 | 15篇 |
2021年 | 18篇 |
2020年 | 11篇 |
2019年 | 9篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 14篇 |
2015年 | 15篇 |
2014年 | 16篇 |
2013年 | 23篇 |
2012年 | 31篇 |
2011年 | 43篇 |
2010年 | 24篇 |
2009年 | 51篇 |
2008年 | 41篇 |
2007年 | 66篇 |
2006年 | 59篇 |
2005年 | 47篇 |
2004年 | 36篇 |
2003年 | 44篇 |
2002年 | 37篇 |
2001年 | 37篇 |
2000年 | 31篇 |
1999年 | 38篇 |
1998年 | 26篇 |
1997年 | 22篇 |
1996年 | 17篇 |
1995年 | 8篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 16篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
排序方式: 共有865条查询结果,搜索用时 15 毫秒
451.
于2008~2012年间在南海北部沿岸海域的23个重要港湾采集近江牡蛎(Crassostrea rivularis Gould )样品,用气相色谱法测定其中多氯联苯(PCBs)的残留量,并对其残留水平、时空分布趋势、组成特征以及食用安全性进行探讨与评价.结果表明:南海北部沿岸牡蛎体内的PCBs的含量范围在8.11~29.10ng/g之间(湿重,下同),平均值是(16.57±4.40)ng/g,出现频率呈正态分布.在时间上,广东、广西和海南沿岸PCBs含量随时间呈下降的总体趋势;空间分布上,珠江口岸段PCBs含量明显高于粤东、粤西、广西和海南4个岸段.PCBs同系物中以五氯联苯在总PCBs含量最高,占47.9%,其次是三氯和四氯联苯,二者之和占总PCBs的30.6%; 同系物以PCBl05、PCB118和PCB101+113为优势组分,3者之和占总量的百分比为24.0%.南海北部沿岸牡蛎体内的PCBs残留量远低于国内外相关食品安全限量标准,估算的沿海居民食用牡蛎的PCBs 暴露量为5.52ng/(kg·d),仅占世界卫生组织(WHO)设定的每日耐受量值的27.6%.PCBs的二 毒性当量(TEQ)平均值为39.4pg/g. 相似文献
452.
Study on tri-axial creep experiment and constitutive relation of different rock salt 总被引:2,自引:0,他引:2
To evaluate the effect of the long-term operation of a salt cavern in a given construction on rock deformation and its stability, tri-axial creep tests to the glauberite, anhydrite, and argillaceous rock salt are conducted, from which the creep curves as well as exponential functions of strain rate during the steady creep stage and creep constitutive equations of different rock salt in the experimental process derived are obtained. The study results show that: (i) Under the same deviatoric stress, the strain rate of argillaceous rock salt is lower than the glauberite and anhydrite, and the difference becomes larger with the increase of the deviatoric stress; (ii) The creep constitutive equations of different kinds of rock salt are in good agreement with the Burgers model, besides which the respective characteristics of these two creep models are compared. The change of creep parameters also illustrates the discrepancy of rock salt. The researching results can provide some references for long-term stability analysis of gas storage in salt caverns. 相似文献
453.
耦合反硝化的CANON生物滤池脱氮研究 总被引:1,自引:0,他引:1
为探究有机物对全程自养脱氮(CANON)工艺的脱氮性能的影响,采用上向流火山岩填料反应器处理模拟废水,在反应器最优工况下实现亚硝化、厌氧氨氧化与反硝化的耦合.结果表明,滤柱在氨氮浓度为200mg/L时的最优总氮去除率均值可达76.73%,总氮去除负荷为2.82kgN/(m3·d).C/N为0.2的有机物水平对反应器的脱氮效果具有促进作用,并可通过HRT的调节实现总氮去除率大于89%(理想条件下CANON的最大脱氮率).因此,通过控制C/N可以提升滤柱氮素去除效率. 相似文献
454.
浮游球衣菌去除废水中Pb2+的研究 总被引:13,自引:4,他引:9
以浮游球衣菌为生物吸附剂,考察了菌铅比、pH、温度和时间等因素对Pb2+吸附的影响.结果表明,浮游球衣菌对Pb2+有很好的吸附效果,该过程10min内即可达到吸附平衡,且温度对吸附效果影响不大.当pH5.5,菌含量0.6 g/L,铅离子初始浓度不大于20 mg/L时,Pb2+去除率近100%,浮游球衣菌最大单位吸附量为2.1 mmol/g干菌体.浮游球衣菌对0~60 mg/LPb2+的吸附符合Freundlich方程.HCl和EDTA溶液可有效地将Pb2+从菌体上解吸下来并可重复使用. 相似文献
455.
This research aimed to screen Bacillus spp. to prevent the production of fly maggot on kitchen wastes from soil in the experimental bases of the South China Agricultural University. A nutrient-rich medium was used to isolate the Bacillus spp. with high temperature treatment. The seventeen Bacillus strains were obtained and assigned to three groups by using Insertion Sequence based PCR (IS-PCR) DNA fingerprinting patterns. The homology of the 16S rDNA gene was 100% between Group I and Bacillus methylotrophicus CBMB 205T, 99.61% between Group II and Bacillus aerophilus 28KT, and 99.87% between Group III and Bacillus cereus ATCC 14579T. The results of kitchen waste tests proved that the representative bacteria of Group I RF2 had the ability to prevent fly maggot production on kitchen wastes. Furthermore, the results of physiological and biochemical tests, carbon utilization tests, and antagonists against plant pathogen tests showed that the bacteria from Group I RF2 had the ability to decompose glucose into pyruvate and then decarboxylate pyruvate to diacetyl under alkaline conditions, convert ammonia to intracellular amino acids or other kinds of nitrogenous compounds, use many kinds of carbon source for self-growth, and be antagonistic against plant pathogenic rice sheath blight disease, banana fusarium wilt, and Fusarium oxysporum. Besides, the bacteria from RF2 could secret organic acids to dissolve insoluble phosphate [Ca3(PO4)2] for its own growth by decreasing the pH. Group I RF2 was a strong plant-promotion bacterium, and had good prospects of application for preventing fly maggot production on kitchen wastes. © 2018 Science Press. All rights reserved. 相似文献
456.
Elena D. Concepción 《Conservation biology》2021,35(4):1063-1072
Urban growth is a major threat to biodiversity conservation at the global scale. Its impacts are expected to be especially detrimental when it sprawls into the landscape and reaches sites of high conservation value due to the species and ecosystems they host, such as protected areas. I analyzed the degree of urbanization (i.e., urban cover and growth rate) from 2006 to 2015 in protected sites in the Natura 2000 network, which, according to the Habitats and Birds Directives, harbor species and habitats of high conservation concern in Europe. I used data on the degree of land imperviousness from COPERNICUS to calculate and compare urban covers and growth rates inside and outside Natura 2000. I also analyzed the relationships of urban cover and growth rates with a set of characteristics of Natura sites. Urban cover inside Natura 2000 was 10 times lower than outside (0.4% vs. 4%) throughout the European Union. However, the rates of urban growth were slightly higher inside than outside Natura 2000 (4.8% vs. 3.9%), which indicates an incipient urban sprawl inside the network. In general, Natura sites affected most by urbanization were those surrounded by densely populated areas (i.e., urban clusters) that had a low number of species or habitats of conservation concern, albeit some member states had high urban cover or growth rate or both in protected sites with a large number of species or habitats of high conservation value. Small Natura sites had more urban cover than large sites, but urban growth rates were highest in large Natura sites. Natura 2000 is protected against urbanization to some extent, but there is room for improvement. Member states must enact stricter legal protection and control law enforcement to halt urban sprawl into protected areas under the greatest pressure from urban sprawl (i.e., close to urban clusters). Such actions are particularly needed in Natura sites with high urban cover and growth rates and areas where urbanization is affecting small Natura sites of high conservation value, which are especially vulnerable and concentrated in the Mediterranean region. 相似文献
457.
介绍了一种项目部HSE管理模式——“一个中心,两个基本点”管理模式,论述了建立该模式的方法,对该模式的拓延性进行了探讨。 相似文献
458.
Wanqi Qi Weiying Li Junpeng Zhang Xuan Wu Jie Zhang Wei Zhang 《Frontiers of Environmental Science & Engineering》2019,13(1):15
459.
Redondas V Gómez X García S Pevida C Rubiera F Morán A Pis JJ 《Waste management (New York, N.Y.)》2012,32(1):60-66
The production of H2 by biological means, although still far from being a commercially viable proposition, offers great promise for the future. Purification of the biogas obtained may lead to the production of highly concentrated H2 streams appropriate for industrial application. This research work evaluates the dark fermentation of food wastes and assesses the possibility of adsorbing CO2 from the gas stream by means of a low cost biomass-based adsorbent. The reactor used was a completely stirred tank reactor run at different hydraulic retention times (HRTs) while the concentration of solids of the feeding stream was kept constant. The results obtained demonstrate that the H2 yields from the fermentation of food wastes were affected by modifications in the hydraulic retention time (HRT) due to incomplete hydrolysis. The decrease in the duration of fermentation had a negative effect on the conversion of the substrate into soluble products. This resulted in a lower amount of soluble substrate being available for metabolisation by H2 producing microflora leading to a reduction in specific H2 production.Adsorption of CO2 from a gas stream generated from the dark fermentation process was successfully carried out. The data obtained demonstrate that the column filled with biomass-derived activated carbon resulted in a high degree of hydrogen purification. Co-adsorption of H2S onto the activated carbon also took place, there being no evidence of H2S present in the bio-H2 exiting the column. Nevertheless, the concentration of H2S was very low, and this co-adsorption did not affect the CO2 capture capacity of the activated carbon. 相似文献
460.
反核生化恐怖与大气科学 总被引:6,自引:5,他引:1
在组成反恐战略诸要素中 ,科技政策是核心要素。“9·1 1”事件后 ,反恐上升为美国科技领域的头号课题 ,政府加大了对科技反恐的投入 ,我国也面临同样的抉择。恐怖活动除了直接实施核生化恐怖威胁之外 ,还通过破坏核生化设施同样达到核生化恐怖的效果 ,甚至比直接实施核生化恐怖更为严重。据调查 ,各大中城市生产使用有毒、有害、易燃、易爆化学物质的工厂占全部工厂的 80 %以上 ,年用量成千上万吨。在恐怖分子应用最多的爆炸和燃烧事件中 ,人员的主要伤亡不是来自于炸伤、烧伤 ,而是因爆炸和燃烧所产生的毒气中毒。研究表明 ,在各种有毒物质传播途径中 ,空气和水体扩散所占比例最大。笔者针对反恐问题 ,论述了大气科学与核生化恐怖的关系 ,重点突出了大气科学、空气动力学及流体力学在反核生化恐怖科研中的战略地位 相似文献