全文获取类型
收费全文 | 2115篇 |
免费 | 166篇 |
国内免费 | 1025篇 |
专业分类
安全科学 | 41篇 |
废物处理 | 63篇 |
环保管理 | 181篇 |
综合类 | 1542篇 |
基础理论 | 663篇 |
污染及防治 | 440篇 |
评价与监测 | 283篇 |
社会与环境 | 93篇 |
出版年
2024年 | 25篇 |
2023年 | 93篇 |
2022年 | 105篇 |
2021年 | 111篇 |
2020年 | 99篇 |
2019年 | 99篇 |
2018年 | 108篇 |
2017年 | 107篇 |
2016年 | 114篇 |
2015年 | 156篇 |
2014年 | 159篇 |
2013年 | 351篇 |
2012年 | 163篇 |
2011年 | 173篇 |
2010年 | 147篇 |
2009年 | 143篇 |
2008年 | 174篇 |
2007年 | 175篇 |
2006年 | 167篇 |
2005年 | 103篇 |
2004年 | 80篇 |
2003年 | 91篇 |
2002年 | 67篇 |
2001年 | 64篇 |
2000年 | 31篇 |
1999年 | 32篇 |
1998年 | 32篇 |
1997年 | 24篇 |
1996年 | 26篇 |
1995年 | 19篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有3306条查询结果,搜索用时 15 毫秒
651.
A study of allozyme spectra has been performed in dandelion cenopopulations growing for a long time under conditions of chemical pollution (the zone of the Nizhnii Tagil Metallurgical Plant, NTMP) or radioactive contamination (the zone of the Eastern Ural Radioactive Trace, EURT). Cenopopulations from the NTMP and EURT zones and from the background area differ significantly in the qualitative and quantitative composition of allozyme phenes. An analysis of clonal diversity has shown that all cenopopulations are phenogenetically unique. The genesis of each cenopopulation proceeded in a specific way: they had different sets of progenitor plants, whose descendants varied genetically in the course of their reproduction and more or less successful colonization of habitats, undergoing selection under the impact of natural environmental factors and technogenic stress. An increased variability of enzyme systems, compared to the sample from the background area, and, as a consequence, reduced clonal diversity may be regarded as a trait common to populations exposed to chemical or radiation stress. 相似文献
652.
Trends in the accumulation of metals by different plant species have been analyzed in a forest phytocenosis of the southern taiga zone of the Middle Urals, which is polluted by emissions from a copper-smelting plant. The rate of metal accumulation in the course of annual and net phytomass production and metal outflow with surface waters beyond the biogeocenosis boundaries have been estimated.Translated from Ekologiya, No. 1, 2005, pp. 26–31.Original Russian Text Copyright © 2005 by Fedorova, Odintseva. 相似文献
653.
通过对受矿山活动影响的贵州阿哈水库沉积物-水界面的模拟试验及实测分析,从水库水质安全角度讨论了沉积物中蓄积的重金属作为二次污染源的可能性。研究发现:在水体季节性缺氧期间,沉积物中部分重金属元素将大量释放到水体中,严重威胁水质安全。Fe,Mn的最大释放发生在水体缺氧事件的50小时内。而Co,Cu,Ni,Pb等元素总体释放量较小,并主要在10小时内达到最大释放。对比其他地区,阿哈水库中重金属元素具有更强的界面扩散作用。锰的扩散通量在季节上表现为:冬季>秋季>春夏季。而铁的扩散通量则为:春夏季>秋季>冬季。锰的界面扩散通量远大于铁的界面扩散通量,表明界面附近锰的循环极为剧烈且远强于铁。这对其他重金属元素的界面循环产生了重要影响。界面附近的铁、锰、硫循环对重金属迁移有着显著的控制作用。受到氧化还原条件的影响,重金属扩散通量在季节上变化较大。 相似文献
654.
The epiphytic moss Hypnum cupressiforme has been used for passive monitoring of airborne heavy metals pollution by vehicular traffic in the urban area of Florence. Lead, cadmium, zinc and copper were determined by differential pulse anodic stripping voltammetry (DPASV). in the summer of 1993 about 30 samples were collected from the trunks of holm oak at the same height (1 metre) from the soil. Lead contents fall within the range of 0.02-1.08 μ moles g-1 (dry weight) and for this metal, the emission source may be attributed mainly to vehicular traffic in poorly industrialized urban areas. Some evaluations have been carried out about the employment of Zn/Pb molar ratio for characterizing airborne pollution in urban areas. 相似文献
655.
The distribution of Fe, Zn, Cu, Cd, Mn, Pb, and Ni in the organs and tissues (kidneys, liver, lungs, brain, heart, muscles, and feathers) of the European black vulture (Aegypius monachus) was studied. It was shown that heavy metals were not responsible for the mass mortality of these birds in southern Primorye in the winter of 2001–2002. The level of pollution with heavy metals of the range of European black vultures wintering in this region (northern China and western Mongolia) may be regarded as insignificant. 相似文献
656.
Sediments collected from Tap Mun (within Tolo Harbour) and Yim Tin Tsai (outside Tolo Harbour) were extracted sequentially
and the copper, cadmium, and chromium contents were determined. Total contents of copper, cadmium, chromium, and arsenic were
also detected by acid digestion. The level of heavy metal extracted was higher in sequential extraction (which extracted all
forms of metal ions) than total acid digestion. Among the four heavy metals studied, only copper showed a significantly higher
(P<0.001) level in samples collected from Yim Tin Tsai (16.10 mg/kg) than that from Tap Mun (3.19 mg/kg). Such a difference
in copper level is mainly attributed to the significantly higher (P<0.05) levels of copper in the organic, carbonate, and sulfide forms, whereas there was no significant difference (P>0.05) in the exchangeable and sorbed forms.
Green-lipped mussel (Perna viridis) samples collected from the two sites were dissected into seven parts (gill, byssus, siphon, shell, digestive gland, soft
tissue, and adductor muscle) and the concentrations of copper, cadmium, chromium, and arsenic were measured. The highest concentration
of copper was obtained in the byssus. A higher concentration of copper was also noted in the mussels collected from Yim Tin
Tsai than those collected from Tap Mun. No specific trend was revealed for the other metals tested. Chromium and arsenic concentrations
were found to be independent of the body size of the mussels. Copper had a lower concentration in larger mussels and cadmium
level was found to decrease with size. In addition, the mussels collected from Tap Mun were much larger than those collected
from Yim Tin Tsai. 相似文献
657.
Kyle B. Combest 《Journal of the American Water Resources Association》1991,27(1):19-28
ABSTRACT: Sediment bound trace metals are often examined for spatial trends such as downstream patterns or distance from a source. Spatial trends may indicate either differences in metal inputs, or, when considerable sediment variability exists, differences in sediment sorption processes. These two possibilities become important not only when sediment contamination is evaluated within an area, but also when regulatory agencies attempt to make equivalent among area decisions. Sediments from an urban watershed were examined for: (1) downstream trace metal trends and (2) sediment sorption relationships. Analyses determined that downstream trenda as related to metal inputs could not be recognized by analyzing the < 2mm (≤, sand) sediment size fraction. Conversely, the trace metal concentrations were found to be distinctly related to sediment characteristics. The watershed's metal concentrations are similar to those found in uncontaminated to slightly contaminated sediments in the United States. 相似文献
658.
659.
660.
Concentration level of heavy metals in the Great Wall Bay, Antarctica in austral summer 总被引:1,自引:0,他引:1
ConcentrationlevelofheavymetalsintheGreatWallBay,Antarcticainaustralsummer¥PuJiabin;FuYunna;LiZhongping(InstituteofMarineEnvi... 相似文献