全文获取类型
收费全文 | 2823篇 |
免费 | 311篇 |
国内免费 | 1318篇 |
专业分类
安全科学 | 141篇 |
废物处理 | 325篇 |
环保管理 | 215篇 |
综合类 | 2276篇 |
基础理论 | 657篇 |
污染及防治 | 564篇 |
评价与监测 | 200篇 |
社会与环境 | 30篇 |
灾害及防治 | 44篇 |
出版年
2024年 | 6篇 |
2023年 | 36篇 |
2022年 | 62篇 |
2021年 | 87篇 |
2020年 | 95篇 |
2019年 | 83篇 |
2018年 | 102篇 |
2017年 | 124篇 |
2016年 | 148篇 |
2015年 | 176篇 |
2014年 | 191篇 |
2013年 | 312篇 |
2012年 | 267篇 |
2011年 | 255篇 |
2010年 | 202篇 |
2009年 | 201篇 |
2008年 | 175篇 |
2007年 | 240篇 |
2006年 | 224篇 |
2005年 | 167篇 |
2004年 | 151篇 |
2003年 | 150篇 |
2002年 | 127篇 |
2001年 | 104篇 |
2000年 | 98篇 |
1999年 | 98篇 |
1998年 | 106篇 |
1997年 | 83篇 |
1996年 | 72篇 |
1995年 | 60篇 |
1994年 | 41篇 |
1993年 | 33篇 |
1992年 | 48篇 |
1991年 | 43篇 |
1990年 | 17篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有4452条查询结果,搜索用时 234 毫秒
421.
低压离子色谱法测定水和酸雨样品中的Li~+,Na~+,NH_4~+,K~+,Ca~(2+)和Mg~(2+)离子 总被引:3,自引:0,他引:3
本文介绍了低压离子色谱仪测定水样(井水、湖水、矿泉水、自来水)和酸雨中锂、钠、铵、钙、钾和镁离子的方法、欲测阳离子在阳离子交换柱上被分离,分别用1.4mmol·1~(-1)HNO_3和0.6mmol·1~(-1)乙二胺+1.2mmol·1~(-1)HNO_3溶液作流动相,流速为1.6ml·min~(-1).各离子的流分用电导检测.进样量为10μl时,Li~+,Na~+,NH_4~+,K~+,Ca~(2+)和Mg~(2+)离子的检出限(2倍噪音比),分别为0.020,0.050,0.100,0.250,2.5和1.0μg·ml~(-1). 相似文献
422.
童贯和 《生态与农村环境学报》2005,21(1):47-50
用模拟酸雨淋洗土壤,造成土壤酸化和盐基流失,然后播种小麦(Triticumaestivum)。幼苗长至5片叶子时的测定表明:幼苗的生物量、叶片叶绿素含量和光合速率均降低,次生根减少,根系活动下降。酸化土壤对根系生物量和某些生理活动的影响大于对地上部的影响。 相似文献
423.
424.
Soichi?Kugimiya Ritsuo?NishidaEmail author Masayuki?Sakuma Yasumasa?Kuwahara 《Chemoecology》2003,13(4):169-175
Summary. Males of the German cockroach, Blattella
germanica, secrete a pheromonal substance from the abdominal tergal glands,
which elicits a feeding response in females during the sequential courtship behavior.
The nuptial secretion consists predominantly of a synergistic mixture of sugars
and phospholipids. Cholesterol and a series of amino acids, which are also
components of the males glandular secretion, significantly enhanced the phagostimulant
activity of the sugar components. The nuptial feeding behavior of the female cockroach
is therefore elicited by a complex assortment of nutritive components in the male
tergal secretion, including sugars, phospholipids, cholesterol, and amino acids. These
results indicate that a mixture of primary metabolites, and not of specific secondary
metabolites, serves as a pheromonal cue that appeals to the females gustatory sense
and effectively brings her to the precopulatory position. Although the
male secretion consists of nutrients, we suggest that these compounds probably do not
represent a significant nutrient investment in females and their progeny but rather
function as a signal in the mating sequence of B. germanica. 相似文献
425.
超高浓度萘系磺酸染料中间体废液资源化 总被引:1,自引:0,他引:1
王连生 《城市环境与城市生态》1995,8(3):11-14
本文介绍了胺盐萃取回收率液中萘磺酸染料中间体的方法,回收率达95%以上,回收浓缩液工艺套用,10t/d废液量的资源化年净效益达580万元,投资费用两个月即可全部收回,采用Langmuir等温方程描述体系中萃取剂用量,待萃物含量和萃取率的关系,使工艺参数的确立和工程设计完全处理指导之下。 相似文献
426.
荔枝花雄蕊和雌蕊发育过程中碳氮化合物的动态变化 总被引:10,自引:0,他引:10
比较分析了荔枝花性决定中碳氮化合物的动态变化。结果发现:C/N较大有利于雄蕊分化,反之则有利于雌蕊分化;氨基酸含量较高有利于雌蕊分化,雄蕊的氨基酸含量仅为雌蕊的一半。脯氨酸与花粉育性存在着密切相关关系。另外,探讨了雌蕊或雄蕊败育的生理意义,在长期的进化中,败育的雌蕊或雄蕊“废物”重新被利用,为同一花中迅速发育的雌蕊或雄蕊提供能量和物质的需求,表5参13。 相似文献
427.
复合垂直流构建湿地净化酞酸酯的初步研究 总被引:5,自引:1,他引:5
为考察湿地对特殊污染物酞酸酯的净化作用,在温室中建造了专门用于酞酸酯研究的2套下行流-上行流湿地小试系统,1号系统邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二(2-乙基已基)酯(DEHP)污染负荷分别为19.86mgL^-1和3.16mgL^-1,2号系统DBP和DEHP污染负荷分别为9.84mgL^-1和1.58mgL^-1,试验时间为45d。水力负荷为420Ld^-1。结果表明:构建湿地对人工配置污水中的酞酸酯有很好的净化效果。平均去除率达到99.95%以上,出水酞酸酯质量浓度为10^-9级,均低于国家排放标准(GB8978-1996). 相似文献
428.
Heikens A Widianarko B Dewi IC De Boer JL Seinen W van Leeuwen K 《Environmental geochemistry and health》2005,27(5-6):409-418
In Asembagus (East Java, Indonesia) irrigation water is contaminated with effluent from the hyperacid Ijen Crater Lake resulting
in a low pH and high levels of various elements. As a first step towards a risk assessment, locally produced food items (rice,
maize, cassava leaf, cassava root, peanuts) were collected and concentrations of As, B, Ca, Cd, Co, Cu, Fe, Mg, Mn, Mo, Ni,
Pb, V, Zn were compared to samples from a reference area and with literature values. Further, concentrations in rice were
compared to total soil concentrations in paddy fields. Compared to the reference area, food items produced in the contaminated
area had increased levels of Cd, Co, Ni and Mn in particular, while levels of Mo were lower. In contrast, total soil concentrations
of Cd and Mn in particular have decreased whereas especially Mo was increased. In combination with the observed soil acidification,
it is likely that the bioavailable concentration of most elements in the contaminated soil is higher (except for Mo) due to
an increased weathering rate and/or input via the contaminated irrigation water. In terms of human health, concentrations in foods were generally within normal literature
values. However, it was observed that essential elements (in particular Fe) known for their inhibitory effects on e.g. Cd
and Mn toxicity did not accumulate in crops whereas Cd and Mn did. 相似文献
429.
Sondes Melliti Ben Garali Inès Sahraoui Pablo de la Iglesia Mohamed Chalghaf Jorge Diogène Jamel Ksouri 《Chemistry and Ecology》2020,36(1):66-82
ABSTRACTThe seasonal variations in Pseudo-nitzschia species and domoic acid (DA) concentration were investigated, at three shellfish farms in SW coastal Mediterranean. In parallel, the toxicity of mussels was tested. Two distinct groups of species were enumerated according to morphology and size (Pseudo-nizschia delicatissima and P. seriata groups). DA was detected over a nine-week period from July to October 2012 in the Lagoon, with a maximum concentration recorded in July (12.71?ng?DA?L?1). DA was positively correlated with the presence of P. seriata-group and P. delicatissima-group and was mostly occurred during P limitation period in seawater. No DA was found in mussels that were collected during the period of DA absence in seawater. Our results suggest that temperature, salinity, inorganic and organic nutrients were significant for the seasonal dynamics of P. seriata and P. delicatissima groups, but that the P limitation was the most driving factor for DA production in these areas. The relative influence of environmental factors should be further studied to better understand the recent surfacing of massive blooms of toxigenic Pseudo-nitzschia in SW Mediterranean coast. 相似文献
430.
实验发现,碘化二甲基胂(IDA)具有很好的色谱挥发性,在5%,10%SE-30柱上可得到较好的色谱峰。二甲基胂酸(DMA)碘化后生成碘化二甲基胂(IDA)。本文提出了新的碘化萃取体系:SnCl_2-KI(1moI/l)-HCl(6mol/l)-甲苯。该体系具有转化率高、干扰少的优点。实验还发现,经过阳离子交换树脂富集,有效地消除了低浓度时,DMA转化中或转化后的分解或吸附对测定的影响,从而提高了分析结果的准确度。 相似文献