全文获取类型
收费全文 | 1004篇 |
免费 | 194篇 |
国内免费 | 559篇 |
专业分类
安全科学 | 69篇 |
废物处理 | 58篇 |
环保管理 | 56篇 |
综合类 | 966篇 |
基础理论 | 328篇 |
污染及防治 | 209篇 |
评价与监测 | 55篇 |
社会与环境 | 12篇 |
灾害及防治 | 4篇 |
出版年
2023年 | 18篇 |
2022年 | 48篇 |
2021年 | 74篇 |
2020年 | 38篇 |
2019年 | 60篇 |
2018年 | 126篇 |
2017年 | 55篇 |
2016年 | 65篇 |
2015年 | 57篇 |
2014年 | 60篇 |
2013年 | 97篇 |
2012年 | 98篇 |
2011年 | 110篇 |
2010年 | 77篇 |
2009年 | 95篇 |
2008年 | 72篇 |
2007年 | 78篇 |
2006年 | 70篇 |
2005年 | 60篇 |
2004年 | 53篇 |
2003年 | 65篇 |
2002年 | 43篇 |
2001年 | 40篇 |
2000年 | 42篇 |
1999年 | 29篇 |
1998年 | 19篇 |
1997年 | 19篇 |
1996年 | 17篇 |
1995年 | 24篇 |
1994年 | 9篇 |
1993年 | 15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 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有1757条查询结果,搜索用时 78 毫秒
901.
建立了以亲水性离子液体1-丁基-3-甲基咪唑四氟硼酸[Bmim]BF4和Na H2PO4形成的二元双水相作为气浮溶剂分离/富集水样中盐酸多西环素的新方法,并采用紫外分光光度法对盐酸多西环素进行测定。考察了离子液体的初始加入量、盐的种类及浓度、p H值、浮选时间及N2流速等因素对体系浮选分离盐酸多西环素的影响。结果表明,改变离子液体和无机盐的加入量,会使体系的富集倍数发生变化,从而使体系的浮选效率和浓集系数发生变化;随浮选时间增加,体系的浮选效率先增加后略微下降;过大或过小的N2流速都会使体系对盐酸多西环素的浮选效率降低;而p H值对体系浮选盐酸多西环素影响不大。当[Bmim]BF4溶液加入量为3 m L、Na H2PO4加入量为25 g(质量分数为33.3%)、气浮时间为40 min、气浮速率为50 m L/min时,体系的浮选效率最高,可达95.8%,浓集系数可达23.95,此时体系的p H值为4.38。与离子液体双水相萃取(ILATPE)相比,该方法的优点在于不仅有较高的浮选率、浓集系数,还有效减少了离子液体的用量,同时操作更简单、环境友好。 相似文献
902.
Binary oxide systems (CuCr2O4, CuCo2O4), deposited onto cordierite monoliths of honeycomb structure with a second support (finely dispersed Al2O3), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine's gas exhausts (O2, NOx, H2O, CO2) and O3 as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO2. Oxidants used can be arranged with reference to decreasing their activity in a following series: O3 >> NO2 > H2O > NO > O2 > CO2. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O3 occurs intensively (in the presence of copper chromite based catalyst) even at closing to ambient temperatures. Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the "cold start" problem. 相似文献
903.
采用批式培养试验重点研究了土壤粒径、NH4+-N和NO3--N及重金属〔Zn和Cr(Ⅵ)〕含量对填埋场砂性覆土及一般砂土CH4氧化能力的影响.结果表明:合适的土壤粒径能显著提高砂性覆土和一般砂土的CH4氧化能力(P0.05),当粒径为1.00~2.00 mm时,砂性覆土和一般砂土的CH4氧化速率分别高达0.24和0.12μmol/(g·h).低浓度NH4+-N或NO3--N均可以促进砂性覆土和一般砂土的CH4氧化,而高浓度则会明显抑制CH4氧化.砂性覆土和一般砂土的外源氨氮和外源NO3--N的投加量(以w计)临界值均为200 mg/kg,砂性覆土对NH4+-N浓度的波动有更好的适应能力;重金属Zn、Cr(Ⅵ)对砂性覆土和一般砂土CH4氧化的抑制作用均随浓度的升高而增强,Zn对砂性覆土CH4氧化的抑制作用程度大于Cr,并且Zn对一般砂土CH4氧化的抑制程度明显强于砂性覆土.为此,筛选合适粒径级配的土壤,同时控制覆土中氮素及重金属的本底含量,有利于填埋场CH4氧化. 相似文献
904.
This paper mainly discusses the effect of Mg(BH4)2 on RDX-based aluminized explosives' energy characteristics. RDX/Mg(BH4)2, RDX/Al/Mg(BH4)2, RDX/AP/Al/Mg(BH4)2 mixed explosives were prepared by molding power method. The influence of energy storage materials on the performance of mixed explosives was discussed by adjusting the proportion of Mg(BH4)2. The impact sensitivity, friction sensitivity, detonation heat experiment, and XPS experiment were carried out for the mixed explosive. The mechanical sensitivity, energy characteristics, and the products after the explosion of the mixed explosive were analyzed. Through the above experiments, it is concluded that Mg(BH4)2 can effectively improve the energy characteristics of RDX, but its safety will become worse after being prepared by a simple mixing method, and the use of the molding power method can effectively reduce the sensitivity. As the mass fraction of Mg(BH4)2 increases and Al decreases, the detonation heat of explosives decreases gradually. Mg(BH4)2 made the oxygen balance of mixed explosives more negative has been considered as a potential reason. Analysis of the detonation heat solid products by XPS found that, unlike our expected results, the product contained a large amount of low calorific value of B2O2 instead of B2O3, which may be a crucial reason. This paper provides a reference for the application of Mg(BH4)2 in energetic materials and is of great significance for the development and application of new materials in energetic materials. 相似文献
905.
906.
The wide occurrence of estrogenic compounds 4-tert-octylphenol, 4-nonylphenol, bisphenol A in surface water of Guanting Reservoir was successfully determined. The target compounds in water samples were preconcentrated by liquid-liquid extraction with dichloromethane, derivatized by trifluoroacetic anhydride, and quantified by gas chromatography-mass spectrometry(GC-MS) with selected ion monitoring(SlM). In the selected seven sampling sites(S1-S7), the concentration of NP in sample S7 was significantly higher than the other in reservoir. The status of pollution in S3 and S7 were much more serious. The concentrations of OP, NP and BPA were in the range of 44.5-48.8, 221.6-349.6 and 30.2-82.7 ng/L, respectively. The pollutants were mainly inputted from the upper river and released from sediments in Guanting Reservoir. 相似文献
907.
以Fe Cl_3·6H_2O和正硅酸四乙酯为原料,通过溶胶-凝胶法结合醇溶剂热法制备了Fe_3O_4@Si O_2复合气凝胶。采用XRD,FTIR,SEM,EDS等技术对Fe_3O_4@Si O_2的结构进行了表征。考察了Fe_3O_4@Si O_2对刚果红溶液的吸附性能。表征结果显示,Fe_3O_4@Si O_2复合气凝胶是由直径为10~20 nm的近球形颗粒组装而成的具有三维网络结构的纳米材料,比表面积为457.93 m~2/g,平均孔径为10.7 nm。在溶液p H为5、吸附时间为35 min的最佳工艺条件下,采用Fe_3O_4@Si O_2吸附处理质量浓度为10 mg/L的刚果红溶液,刚果红去除率为99.39%,此时溶液中刚果红的质量浓度仅为0.052 mg/L。Fe_3O_4@Si O_2复合气凝胶吸附刚果红后具有较好的解吸和再生能力。 相似文献
908.
909.
910.
COD/SO42-值对硫酸盐废水厌氧消化的影响 总被引:2,自引:0,他引:2
采用间歇试验方式,研究了COD/SO42-值对硫酸盐废水厌氧消化的影响.试验结果表明,COD/SO42-值是影响厌氧消化处理效果的主要参数.本试验中,COD/SO42->15,硫酸盐还原作用对厌氧反应器影响甚微;COD/SO42-=5-15时,硫酸盐还原作用对厌氧反应器产生轻度抑制,相对产甲烷率为79.2%-94.7%;COD/SO42-=0.5-5时,反应器受中度抑制,相对产甲烷率为61.6%-79.2%;COD/SO42-<0.5时,反应器受严重抑制.COD/SO42-≥1时,相对产甲烷率与COD/SO42-值之间有很好的线性关系. 相似文献