全文获取类型
收费全文 | 1892篇 |
免费 | 124篇 |
国内免费 | 637篇 |
专业分类
安全科学 | 135篇 |
废物处理 | 109篇 |
环保管理 | 189篇 |
综合类 | 1044篇 |
基础理论 | 361篇 |
环境理论 | 1篇 |
污染及防治 | 520篇 |
评价与监测 | 128篇 |
社会与环境 | 85篇 |
灾害及防治 | 81篇 |
出版年
2024年 | 7篇 |
2023年 | 36篇 |
2022年 | 97篇 |
2021年 | 92篇 |
2020年 | 89篇 |
2019年 | 75篇 |
2018年 | 81篇 |
2017年 | 87篇 |
2016年 | 91篇 |
2015年 | 99篇 |
2014年 | 131篇 |
2013年 | 153篇 |
2012年 | 155篇 |
2011年 | 136篇 |
2010年 | 137篇 |
2009年 | 143篇 |
2008年 | 149篇 |
2007年 | 128篇 |
2006年 | 115篇 |
2005年 | 64篇 |
2004年 | 65篇 |
2003年 | 63篇 |
2002年 | 58篇 |
2001年 | 49篇 |
2000年 | 57篇 |
1999年 | 55篇 |
1998年 | 30篇 |
1997年 | 21篇 |
1996年 | 19篇 |
1995年 | 17篇 |
1994年 | 15篇 |
1993年 | 16篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1967年 | 3篇 |
排序方式: 共有2653条查询结果,搜索用时 15 毫秒
131.
Guiqiang Li Jie Ji Yuehong Su Hang Zhou Jingyong Cai 《International Journal of Green Energy》2016,13(9):944-950
The primary lens-walled compound parabolic concentrator (lens-walled CPC) has a significant advantage of a larger half acceptance angle as a static solar concentrator, but it also has a drawback of a low optical efficiency. In order to overcome this drawback, in this article, series of structure parameters were investigated and compared to further improve the optical efficiency within the half acceptance angle combined with the material properties. The average optical efficiencies of the improved lens-walled CPCs could achieve more than 82% within the half acceptance angle of 35?. Experiments were adopted to verify the credibility and validity of the simulation. Moreover, annual performance of the lens-walled CPCs comparison with that of the mirror CPC for Nottingham was analyzed. Results show that the improved lens-walled CPC has a higher optical performance for actual building application. 相似文献
132.
Lee Jaewoong Park Taejin Kim Min-seob Kim Jongmin Lee Seunghyun Lee Su Kyuong Lee Young Sun Lee Won-seok Yu Soonju Rhew Doughee 《Environmental science and pollution research international》2016,23(18):18175-18182
Environmental Science and Pollution Research - We investigated the distribution of nitrogen compounds in Han River as well as two tributaries of Tancheon and Jungrangcheon. Particularly, we... 相似文献
133.
Tsatsral Batmunkh KwangYul Lee Young J. Kim Min-Suk Bae Shila Maskey 《Journal of the Air & Waste Management Association (1995)》2016,66(2):151-163
Carbonaceous components (organic carbon [OC] and elemental carbon [EC]) and optical properties (light absorption and scattering) of fine particulate matter (aerodynamic diameter <2.5 μm; PM2.5) were simultaneously measured at an urban site in Gwangju, Korea, during the winter of 2011. OC was further classified into OC1, OC2, OC3, and OC4, based on a temperature protocol using a Sunset OC/EC analyzer. The average OC and EC concentrations were 5.0 ± 2.5 and 1.7 ± 0.9 μg C m?3, respectively. The average single-scattering albedo (SSA) at a wavelength of 550 nm was 0.58 ± 0.11, suggesting that the aerosols observed in the winter of 2011 had a local warming effect in this area. During the whole sampling period, “stagnant PM” and “long-range transport PM” events were identified. The light absorption coefficient (babs) was higher during the stagnant PM event than during the long-range transport PM event due to the existence of abundant light-absorbing OC during the stagnant PM event. In particular, the OC2 and OC3 concentrations were higher during the stagnant PM event than those during the long-range transport event, suggesting that OC2 and OC3 might be more related to the light-absorbing OC. The light scattering coefficient (bscat) was similar between the events. On average, the mass absorption efficiency attributed to EC (σEC) was 9.6 m2 g?1, whereas the efficiency attributed to OC (σOC) was 1.8 m2 g?1 at λ = 550 nm. Furthermore, the σEC is comparable among the PM event days, but the σOC for the stagnant PM event was significantly higher than that for the long-range transport PM event (1.7 vs. 0.5).Implications: Optical and thermal properties of carbonaceous aerosol were measured at Gwangju, and carbonaceous aerosol concentration and optical property varied between “stagnant PM” and “long-range transport PM” events. More abundant light absorbing OC was observed during the stagnant PM event. 相似文献
134.
Cora J. Young Michael D. Hurley Timothy J. Wallington Scott A. Mabury 《Atmospheric environment (Oxford, England : 1994)》2009,43(24):3717-3724
Relative rate techniques were used to determine k(Cl + CF3CFCFCF3) = (7.27 ± 0.88) × 10?12, k(Cl + CF3CF2CFCF2) = (1.79 ± 0.41) × 10?11, k(OH + CF3CFCFCF3) = (4.82 ± 1.15) × 10?13, and k(OH + CF3CF2CFCF2) = (1.94 ± 0.27) × 10?12 cm3 molecule?1 s?1 in 700 Torr of air or N2 diluent at 296 K. The chlorine atom- and OH radical-initiated oxidation of CF3CFCFCF3 in 700 Torr of air gives CF3C(O)F in molar yields of 196 ± 11 and 218 ± 20%, respectively. Chlorine atom-initiated oxidation of CF3CF2CFCF2 gives molar yields of 97 ± 9% CF3CF2C(O)F and 97 ± 9% COF2. OH radical-initiated oxidation of CF3CF2CFCF2 gives molar yields of 110 ± 15% CF3CF2C(O)F and 99 ± 8% COF2. The atmospheric fate of CF3CF2C(O)F and CF3C(O)F is hydrolysis to give CF3CF2C(O)OH and CF3C(O)OH. The atmospheric lifetimes of CF3CFCFCF3 and CF3CF2CFCF2 are determined by reaction with OH radicals and are approximately 24 and 6 days, respectively. The contribution of CF3CFCFCF3 and CF3CF2CFCF2 to radiative forcing of climate change will be negligible. 相似文献
135.
Juan G. Navea Shihe Xu Charles O. Stanier Mark A. Young Vicki H. Grassian 《Atmospheric environment (Oxford, England : 1994)》2009,43(26):4060-4069
We have carried out kinetic studies to characterize the heterogeneous decay of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in the presence of representative mineral dust aerosol in order to obtain a better understanding of the atmospheric fate of these siloxanes. The heterogeneous chemistry of D4 and D5 with various mineral dusts was studied in an environmental aerosol reaction chamber using FTIR absorption spectroscopy to monitor the reaction. The apparent heterogeneous uptake coefficient, γapp, for D4 and D5 with various mineral dusts was measured under dry conditions and as a function of relative humidity (RH). In addition, the effect of initial D4 and D5 concentration on the rate and yield of the reaction was examined. The uptake coefficient, γapp, for D4 and D5 was similar for the most reactive aerosols tested, with kaolinite ≈hematite > silica. Limited uptake onto carbon black and calcite surfaces was observed for either siloxane. Reaction with hematite and kaolinite resulted in multilayer coverages, suggesting extensive polymerization of D4 and D5 on the aerosol surface. 相似文献
136.
Diversity of Soil Nematodes in Areas Polluted with Heavy Metals and Polycyclic Aromatic Hydrocarbons (PAHs) in Lanzhou,China 总被引:1,自引:0,他引:1
This study investigated the soil nematode community structure along the Yellow River in the Lanzhou area of China, and analyzed
the impact of heavy metals (Cd, Pb, Cr, Cu, and Zn) and polycyclic aromatic hydrocarbons (PAHs) on the nematode community.
Soil samples from five locations (named A–E), which were chosen for soil analysis, showed significant differences in their
heavy metal content (p < 0.01), as well as in the variety of nematodes (up to 41 genera) and families (up to 20) that were present. The different
samples also differed significantly in the total PAH content (p < 0.05), as well as the six types of PAH present. Sites A–C showed the most severe contamination with heavy metals and PAHs;
these sites had the lowest abundance of fungivores and omnivore/predators, but the proportion of bacteriovores was the highest
(p < 0.05). Site E, in contrast, showed only minor pollution with heavy metals and PAHs, and it contained the highest abundance
of plant parasites (p < 0.05). Several nematode ecological indicators were found to correlate with concentration of soil pollutants at all the
sites tested: the maturity index (MI, in addition to plant parasites), plant parasite index (PPI), ΣMI (including all the
soil nematodes), Shannon-Wiener diversity index (H′′), and Wasilewska index (WI). Disturbance to the soil environment was more severe when MI, ΣMI, and H′ values were lower. The results of the study show that the abundance and structure of the soil nematode communities in the
sampling locations were strongly influenced by levels of heavy metals and PAHs in the soil. They also show that the diversity
index H′ and the maturity index can be valuable tools for assessing the impact of pollutants on nematodes. 相似文献
137.
As part of a comprehensive environmental management system, many countries establish emission control targets for mass emissions of a pollutant. Such targets are often the key objective of an environmental policy, such as an emission trading program. In China, however, it is more than just an objective of one particular policy; it has become a concept that has influenced many national environmental policies and activities. The objective of this article is to review the implementation of the total emission c... 相似文献
138.
The possibility of using coal fly ash as a silica source for alkali borosilicate glass was investigated. Alkali borosilicate glasses were prepared from the coal fly ash mixed with 30 wt.% reagents composed of Na(2)O and B(2)O(3) by susceptor-induction heating. Their densities ranged from 2.24 to 2.55 g cm(-3) and decreased as the amount of B(2)O(3) addition increased. However, the Vickers microhardness showed a different tendency with the density since the glass network connectivity improved by boron anomaly, which was identified by a nuclear magnetic resonance analysis. The Vickers microhardness of the glass product, with the addition of 15 wt.% B(2)O(3) and 15 wt.% Na(2)O, was about 4030 MPa. Furthermore, the changes in microstructure were consistent with those in the chemical stability by the toxicity characteristic leaching procedure (TCLP). 相似文献
139.
浸提分离法提取皂素清洁工艺研究 总被引:2,自引:0,他引:2
提出一种通过溶剂提取将游离皂苷与淀粉、纤维等成分分离,从源头上减少用水量、耗酸量和污染物排放量的皂素清洁生产工艺。首先对溶剂提取条件进行优化,得出最佳工艺条件为:90%(体积比)乙醇溶液,料液比1∶7,沸腾回流提取3 h,重复提取3次。然后通过气质联用(GC/MS)分析了皂素废水的有机物组成。研究结果表明,清洁工艺皂素产率为1.51%(降低3.82%),用酸量比传统工艺减少了71%,头道液COD浓度降低了46%,每100 g原料排放的COD总量下降了84%;皂素废水的有机物污染物主要为糠醛及其衍生物,清洁工艺废水的有机物含量更低,更易降解。 相似文献
140.
3株反硝化聚磷菌的分离与鉴定 总被引:5,自引:0,他引:5
通过烛缸法培养富集、分离,结合除磷试验、硝酸盐还原产气试验及异染颗粒和PHB颗粒染色辅助检验相结合的方法筛选,得到3株具有较高脱氮除磷效率的反硝化聚磷菌DNPA8, DNPA9和DNPA10。在富氮富磷培养基中培养48 h,各菌株的脱氮率均大于75%,除磷率均大于78%。采用多相分类的方法确定了3株反硝化聚磷菌的分类地位,DNPA8为嗜麦芽寡养单胞菌,DNPA9为水生丛毛单胞菌属首次发现的反硝化聚磷菌;DNPA10为约翰逊氏不动杆菌。该研究结果为富营养化水体的治理提供了有效的菌种资源。 相似文献