全文获取类型
收费全文 | 6756篇 |
免费 | 614篇 |
国内免费 | 2818篇 |
专业分类
安全科学 | 365篇 |
废物处理 | 863篇 |
环保管理 | 700篇 |
综合类 | 5548篇 |
基础理论 | 760篇 |
污染及防治 | 1724篇 |
评价与监测 | 173篇 |
社会与环境 | 53篇 |
灾害及防治 | 2篇 |
出版年
2024年 | 8篇 |
2023年 | 32篇 |
2022年 | 89篇 |
2021年 | 113篇 |
2020年 | 132篇 |
2019年 | 134篇 |
2018年 | 162篇 |
2017年 | 194篇 |
2016年 | 243篇 |
2015年 | 328篇 |
2014年 | 463篇 |
2013年 | 545篇 |
2012年 | 671篇 |
2011年 | 666篇 |
2010年 | 533篇 |
2009年 | 554篇 |
2008年 | 416篇 |
2007年 | 705篇 |
2006年 | 790篇 |
2005年 | 566篇 |
2004年 | 433篇 |
2003年 | 466篇 |
2002年 | 400篇 |
2001年 | 310篇 |
2000年 | 252篇 |
1999年 | 220篇 |
1998年 | 173篇 |
1997年 | 126篇 |
1996年 | 115篇 |
1995年 | 107篇 |
1994年 | 69篇 |
1993年 | 64篇 |
1992年 | 32篇 |
1991年 | 19篇 |
1990年 | 20篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1978年 | 4篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 631 毫秒
921.
针对我国生物质气化发电行业的现状,总结诸多风险的影响因素,建立了我国生物质气化发电行业综合风险评价体系。该评价体系主要包括5个一级风险影响因素:市场风险、技术风险、安全风险、管理风险、环境风险,每个一级影响因素包括4个二级风险影响因素。由层次分析法获得各个一级影响因素和二级影响因素的权重值,根据所构建的评价集和评分标准,结合模糊综合评价法对我国生物质气化发电行业现状的综合风险等级做定量定性分析。综合风险评价研究结果表明,生物质气化发电行业处于"较高"的风险等级,与实际情况相符。综合风险评价体系的构建合理,所建立的评价方法以及相应对策分析可为决策者提供参考依据。 相似文献
922.
Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria (PNSB). This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg2+ under the light-anaerobic condition. Results showed that with the optimal Mg2+ dosage of 10 mg/L, biomass production was improved by 70% to 3630 mg/L, and biomass yield also was improved by 60%. Chemical Oxygen Demand (COD) removal reached above 86% and hydraulic retention time was shortened from 96 to 72 hr. The mechanism analysis indicated that Mg2+ could promote the content of bacteriochlorophyll in photosynthesis because Mg2+ is the bacteriochlorophyll active center, and thus improved adenosine triphosphate (ATP) production. An increase of ATP production enhanced the conversion of organic matter in wastewater into PNSB cell materials (biomass yield) and COD removal, leading to more biomass production. With 10 mg/L Mg2+, bacteriochlorophyll content and ATP production were improved by 60% and 33% respectively. 相似文献
923.
Biological removal of antiandrogenic activity in gray wastewater and coking wastewater by membrane reactor process 总被引:1,自引:0,他引:1
A recombinant human androgen receptor yeast assay was applied to investigate the occurrence of antiandrogens as well as the mechanism for their removal during gray wastewater and coking wastewater treatment. The membrane reactor (MBR) system for gray wastewater treatment could remove 88.0% of antiandrogenic activity exerted by weakly polar extracts and 97.3% of that by moderately strong polar extracts, but only 32.5% of that contributed by strong polar extracts. Biodegradation by microorganisms in the MBR contributed to 95.9% of the total removal. After the treatment, the concentration of antiandrogenic activity in the effluent was still 1.05 μg flutamide equivalence (FEQ)/L, 36.2% of which was due to strong polar extracts. In the anaerobic reactor, anoxic reactor, and membrane reactor system for coking wastewater treatment, the antiandrogenic activity of raw coking wastewater was 78.6 mg FEQ/L, and the effluent of the treatment system had only 0.34 mg FEQ/L. The antiandrogenic activity mainly existed in the medium strong polar and strong polar extracts. Biodegradation by microorganisms contributed to at least 89.2% of the total antiandrogenic activity removal in the system. Biodegradation was the main removal mechanism of antiandrogenic activity in both the wastewater treatment systems. 相似文献
924.
采用电化学沉积法将纳米钯粒子负载在钛板上,制备钛负载纳米钯粒子的NanoPd/Ti电极.利用循环伏安法和线性扫描伏安法对比研究NanoPd/Ti电极与Ti电极的电化学性能,以及分别对氯苯和硝基苯模拟废水电化学催化性能,表明NanoPd/Ti电极循环伏安过程出现新的氧化峰和还原峰,反应电位明显正移,反应过程峰电流也明显增大.通过降解实验,NanoPd/Ti电极可以在更低电压,更短时间内达到更好CODcr去除效果. 相似文献
925.
926.
汽车生产过程中伴随着大量的自来水消耗与废水排放,因此,汽车工业具有较大的节能减排潜力.国内某汽车厂采用膜过滤技术对达标排放的废水进行深度处理,中水水质达到冷却水回用标准,作为补充水回用于循环冷却水系统.通过对中水水质的监控和冷却水系统的运行控制,保证中水回用实施效果.结果表明:中水回用后,循环冷却水满足系统运行条件,既节约了自来水的消耗又达到了减少污染物排放的目的,在汽车工业中具有一定的推广应用价值. 相似文献
927.
928.
长江近口段沿岸刀鲚生物量的时间格局 总被引:1,自引:0,他引:1
为了解长江刀鲚Coilia nasus资源的变动状况,探讨沿岸水域对刀鲚资源的保育作用,于2002~2013年间用定制张网对长江靖江段沿岸鱼类作了每月2~3个样本的采集。分析结果显示,12a采集的369份样品中,刀鲚的出现频率达94.6%,分别占总渔获数量和重量的5.18%和5.46%。刀鲚平均CPUEN和CPUEW有16.7±19.9尾和106.6±109.5g,是沿岸鱼类群聚的优势种或次优势种。但其年资源量并不稳定,最高的2010年是最低2002年的5.4陪。平均体长123.6±37.0mm,平均体重仅7.5±8.2g。0+龄组占78.9%,1+龄组占20.7%,2+龄仅出现在4、5月份,且仅占当月个体数的3.0%,幼体是沿岸刀鲚群体的主要组成成分。从0+龄个体的月度体长分布看,当年孵化的幼鱼大多栖息在河岸水域,沿岸生境在维持刀鲚幼鱼资源上具有重要作用。分析显示,4月1日至6月30日的长江禁渔期虽可保护约42.6%的幼鱼个体,但从保护效果看,还因适当延长沿岸水域的禁渔时间。维护沿岸水域的生境完整性,也是保护长江刀鲚幼鱼资源的重要措施。 相似文献
929.
Biomass,as fuelwood,is one of the major sources of energy in rural areas,especially in the mountainous regions of the world.As the increasing human population exerts more pressure on the forest thereby inducing an adverse effect on the sustainability of the ecosystem,which consequently causes fuelwood crisis at a local level,this crisis is spatio-temporal in nature.Thus,the major objective of this study is to assess the sustainability of fuelwood at different probable scenarios at a micro watershed level.The present study was conducted in the Phakot watershed,the Tehri Garhwal district of central Himalaya in India,during 2006-2008.Based on the vegetation composition in the study area,the net primary productivity(NPP)value of the Oak forest,and mixed oak and sal forests,was used for the quantification of fuelwood availability in evergreen and deciduous forests,respectively.The fuelwood demand was calculated on the basis of seasonal fuelwood consumption values.Nine probable permutations for availability-demand scenarios assuming the existence of high(H),low(L)and average(A)conditions were analyzed for evaluating the stress.The available annual harvestable fuelwood in the watershed is in the minimum and maximum ranges of 2283.28 to 4066.00 tons,respectively,per year whereas it has a demand of 110.76 tons as the minimum to 3659 tons as the maximum annually.This shows that in the current availabilitydemand scenario,the watershed does not have fuelwood crisis in the present situation but needs to maintain the sustainability of the system.Based on our study,it is concluded that,globally,more spatio-temporal study is required to understand the issues at the local level. 相似文献
930.
采用GC-MS测定了典型综合印染废水处理厂废水和污泥中芳香烃化合物的含量.结果表明,原水中苯系物总量为203.96±15.18μg·L-1,其中二甲苯占62.7%,尾水中苯系物总量为0.2±0.029μg·L-1,整个处理工艺对苯系物的去除效率为99%.原水中多环芳烃(PAHs)总浓度达1349.51±35.77 ng·L-1,以3—6环为主,主要富集在颗粒物上.整个工艺对PAHs的去除效率为95%,尾水中PAHs总浓度为65.81±20.99ng·L-1,以2—3环为主.干污泥中PAHs含量高达2996.10±151.0 ng·g-1,污泥吸附为水相中PAHs去除的主要机理之一.印染污泥直接填埋或农用会引起潜在的生态危害. 相似文献