全文获取类型
收费全文 | 5851篇 |
免费 | 739篇 |
国内免费 | 746篇 |
专业分类
安全科学 | 1896篇 |
废物处理 | 463篇 |
环保管理 | 833篇 |
综合类 | 2558篇 |
基础理论 | 325篇 |
环境理论 | 7篇 |
污染及防治 | 507篇 |
评价与监测 | 373篇 |
社会与环境 | 130篇 |
灾害及防治 | 244篇 |
出版年
2024年 | 13篇 |
2023年 | 89篇 |
2022年 | 151篇 |
2021年 | 217篇 |
2020年 | 235篇 |
2019年 | 208篇 |
2018年 | 160篇 |
2017年 | 244篇 |
2016年 | 270篇 |
2015年 | 321篇 |
2014年 | 302篇 |
2013年 | 415篇 |
2012年 | 509篇 |
2011年 | 485篇 |
2010年 | 345篇 |
2009年 | 372篇 |
2008年 | 246篇 |
2007年 | 378篇 |
2006年 | 374篇 |
2005年 | 274篇 |
2004年 | 207篇 |
2003年 | 235篇 |
2002年 | 192篇 |
2001年 | 170篇 |
2000年 | 158篇 |
1999年 | 117篇 |
1998年 | 109篇 |
1997年 | 108篇 |
1996年 | 120篇 |
1995年 | 85篇 |
1994年 | 53篇 |
1993年 | 49篇 |
1992年 | 38篇 |
1991年 | 21篇 |
1990年 | 22篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有7336条查询结果,搜索用时 78 毫秒
851.
环境样品中非邻位取代共平面多氯联苯的测定 总被引:6,自引:0,他引:6
本文对测定实际环境样品中痕量非邻位取代共平面多氯联苯的方法进行了研究。样品萃取,净化后,经活性碳性层析分离,利用GC-ECD毛细管柱双柱定性,外标法进行定量,测定了土壤和鱼肌肉中μg·kg^-1数量级的3,3‘,4,4’-四氯联苯及ng·gkg^-1数量级的3,3‘,4’,5-五氯联苯。 相似文献
852.
吸烟气相物质引起的脂质过氧化的研究 总被引:2,自引:0,他引:2
本文用吸烟气相物质作用于卵磷脂形成的脂质体及人多形核白细胞,用TBA法和共轭二烯法检测吸烟气相物质作用下的脂质过氧化水平,结果发现,随着吸烟气相物质作用时间的延长,MDA和共轭二烯的含量也随之增大。表明吸烟气相物质能够引起脂质过氧化反应。 相似文献
853.
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
854.
In the asperillo dune system, Southwest Spain, lichen vegetation covering the dune sand, has a low species diversity but is
an important component of the perennial vegetation, providing stability, nutrients, and moisture to the soil layer. The Asperillo
dunes harbour (1) natural ecosystems, (2) disturbed systems affected by forestry activities where the natural vegetation is
eliminated, and (3) pine forest resulting from afforestation withPinus pinea since the end of the 1940s where the composition and abundance of the lichen flora has been drastically changed.
Our hypothesis was that the lichen species composition and distribution are influenced by the type and period of human intervention.
To test this hypothesis a 1.2 km × 1.1 km area, which includes zones with different degrees of conservation and perturbation,
consisting of five different habitats, was selected: well preservedJuniperus woodland,Pinus pinea plantations with dense scrub, dense scrub,P. pinea plantations cleared from scrub, and pioneer scrub in recent pine afforestation. In each area, randomly located 5m × 5 m homogeneous
plots were sampled. In each plot the cover of shrub and lichen species was recorded.
The first results show that lichen cover is higher in the most preserved areas,Cladonia mediterranea being the dominant species under theJuniperus phoenicea canopy. The lichen community changes in composition and abundance depending on the time elapsed since the last perturbation. 相似文献
855.
大气有机物在脱水,富集过程中的组分损失造成GC分析的系统误差。回收率测定表明,在本实验条件下,疏水性有机组分在填充碱石棉与碳酸钾的脱水预柱上的损失率分别为25%和15%左右,亲水性的乙醇的损失经高达60%左右。 相似文献
856.
In 1990, the Government and Parliament of the Netherlands decided on a new national policy for coastal defence. To ensure
the enduring safety of the low-lying polders as well as the sustainable preservation of the coastal dunes, it was decided
to maintain the coastline in its 1990 position.
The main method for coastline preservation in the Netherlands is beach nourishment. Since 1991, approximately 7 million m3 of sand is added to the Dutch beaches annually. From an evaluation study of sand nourishment projects it is concluded that
nourishment is an effective and efficient method to preserve the coastline. The evaluation study also proves that nourishment
projects should be ‘tailor-made’, taking the local morphological and hydraulic conditions into account. The first results
of an experimental shoreface nourishment are discussed.
The choice for nourishment as the principal method to combat erosion is well in line with the intention to restore the natural
dynamics of the dune-coast in the Netherlands. The key probably is a less strict policy with regard to the maintenance of
the foredunes. Plans for the development of typical coastal features such as slufters*, wash-overs, blow-outs and mobile dunes are currently under discussion.
A slufter is a breakthrough in the first dune-ridge whereby the sea invades former dune slacks or beach plains situated behind
the duneridge. In this way a tidal marsh is formed within the dune zone. 相似文献
857.
858.
SAITOYoshihiro JINNOKiyokatsu 《环境化学》2003,22(3):241-245
1 IntroductionGaschromatography(GC)isoneofthemostpopularseparationmethodsfortheanalysisofvolatilecompounds,andawidevarietyofpolymericmaterialsasthestationaryphases,havebeendeveloped .Incontrasttothesuccessfulapplicationsandsubsequentcommercializationofth… 相似文献
859.
广西大明山自然保护区两栖动物资源调查报告 总被引:1,自引:0,他引:1
2000年9月11日至26日,在广西省大明山自然保护区共采集鉴定两栖类动物66只(种),共计9种,隶属1目,4科.结合以往的调查资料,目前已知大明山自然保护区有两栖动物动物22种,隶属1目,5科,9属.保护区内的两栖类多样性系数(H′)为1.21028,均匀度指数(J)为0.58202. 相似文献
860.
In this study numerical methods are used to investigate the relationship between chemical concentration of gas species within a cavitating bubble, equilibrium radius of the gas bubble and pressure variations in the ambient liquid. For this purpose, governing equations are developed to describe the dynamic equilibrium of a bubble in a flowing fluid and mass transfer between gas and liquid phases, where it was assumed that gases undergo isothermal compression, obey the ideal gas law, Henry law. It is further assumed that the concentration of each phase within the bubble is uniform. The resulting nonlinear equations are solved using implicit Trapezoidal method with Newton iteration. Four gas species are modeled under various initial and ambient pressure variation conditions. These conditions maybe considered to represent typical cavitation events. The numerical results obtained are presented in terms of dimensionless numbers. These results indicate that chemical damage maybe an important component of cavitation surface damage, since high concentration profiles may develop within a collapsing bubble. Proposed formulation and numerical solutions are simple and cost effective to implement. The results presented in this study maybe used to benchmark experimental investigations or other more complex solutions, which are outside the scope of this study. 相似文献