全文获取类型
收费全文 | 2259篇 |
免费 | 215篇 |
国内免费 | 758篇 |
专业分类
安全科学 | 227篇 |
废物处理 | 114篇 |
环保管理 | 204篇 |
综合类 | 1372篇 |
基础理论 | 369篇 |
污染及防治 | 601篇 |
评价与监测 | 129篇 |
社会与环境 | 135篇 |
灾害及防治 | 81篇 |
出版年
2024年 | 7篇 |
2023年 | 39篇 |
2022年 | 142篇 |
2021年 | 127篇 |
2020年 | 115篇 |
2019年 | 79篇 |
2018年 | 94篇 |
2017年 | 111篇 |
2016年 | 99篇 |
2015年 | 118篇 |
2014年 | 166篇 |
2013年 | 218篇 |
2012年 | 203篇 |
2011年 | 199篇 |
2010年 | 177篇 |
2009年 | 184篇 |
2008年 | 175篇 |
2007年 | 175篇 |
2006年 | 158篇 |
2005年 | 110篇 |
2004年 | 66篇 |
2003年 | 78篇 |
2002年 | 54篇 |
2001年 | 53篇 |
2000年 | 43篇 |
1999年 | 37篇 |
1998年 | 32篇 |
1997年 | 36篇 |
1996年 | 30篇 |
1995年 | 29篇 |
1994年 | 12篇 |
1993年 | 18篇 |
1992年 | 12篇 |
1991年 | 16篇 |
1990年 | 2篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有3232条查询结果,搜索用时 15 毫秒
921.
近几年,由于图像监控报警的需求范围迅速扩大,因而有关图像监控系统的研究开发成果屡见不鲜.常规的模拟图像监控系统,由于传输组网产品的发展滞后,尤其是多视点和长距离监控系统的传输组网问题非常突出,它已经成为当前限制模拟图像监控应用发展的瓶颈.数字监控系统是以计算机为核心对图像进行数字化处理后实现数字传输与处理,但对于分散的距离长、视点多实时图像监控,需要的设备费用昂贵.尽管图像监控数字化、网络化是今后的发展方向,但对于普通的应用场合,其性价比将受到考验. 相似文献
922.
Sequence-based source tracking of Escherichia coli based on genetic diversity of beta-glucuronidase 总被引:1,自引:0,他引:1
Ram JL Ritchie RP Fang J Gonzales FS Selegean JP 《Journal of environmental quality》2004,33(3):1024-1032
High levels of fecal bacteria are a concern for recreational waters; however, the source of contamination is often unknown. This study investigated whether direct sequencing of a bacterial gene could be utilized for detecting genetic differences between bacterial strains for microbial source tracking. A 525-nucleotide segment of the gene for beta-glucuronidase (uidA) was sequenced in 941 Escherichia coli isolates from the Clinton River-Lake St. Clair watershed, 182 E. coli isolates from human and animal feces, and 34 E. coli isolates from a combined sewer. Environmental isolates exhibited 114 alleles in 11 groups on a genetic tree. Frequency of strains from different genetic groups differed significantly (p < 0.03) between upstream reaches (Bear Creek-Red Run), downstream reaches, and Lake St. Clair beaches. Fecal E. coli uidA sequences exhibited 81 alleles that overlapped with the environmental set. An algorithm to assign alleles to different host sources averaged approximately 75% correct classification with the fecal data set. Using the same algorithm, the percent of environmental isolates assignable to humans decreased significantly between Bear Creek-Red Run (30 +/- 3%) and the beaches (17 +/- 2%) (p < 0.05). Birds accounted for approximately 50% of assignable environmental isolates. For combined sewer isolates, the same algorithm assigned 51% to humans. These experiments demonstrate differences in the frequency of different E. coli strains at different locations in a watershed, and provide a "proof in principle" that sequence-based data can be used for microbial source tracking. 相似文献
923.
关于中国的水安全问题及其对策探讨 总被引:20,自引:4,他引:16
随着全球性资源生态危机的加剧及全球化进程的飞速发展 ,国家安全要素扩大到包括资源环境在内的一些非传统安全要素上 ,现今 ,水安全已成为国家安全问题的核心内容之一。为此 ,笔者探讨了我国水安全存在的一些主要问题 ;分析了产生这些问题的原因 ;提供了解决这些问题的对策。 相似文献
924.
Estimating runoff phosphorus losses from calcareous soils in the Minnesota River basin 总被引:4,自引:0,他引:4
Bioavailable phosphorus (BAP) in stormwater runoff is a key issue for control of eutrophication in agriculturally impacted watersheds. Laboratory experiments were conducted in soil runoff boxes to determine BAP content in simulated storm runoff in 10 (mostly) calcareous soils from the Minnesota River basin in southern Minnesota. The soluble reactive phosphorus (SRP) portion of the runoff BAP was significantly correlated with soil Mehlich-III P, Olsen P, and water-extractable P (all r2 > 0.90 and p < 0.001). A linear relationship (r2 = 0.88, p < 0.001) also was obtained between SRP in runoff and the phosphorus saturation index based on sorptivity (PSIs) calculated with sorptivity as a measure of the inherent soil P sorption capacity. Runoff levels of BAP estimated with iron oxide-impregnated paper were predicted well by various soil test P methods and the PSI, of the soils, but correlation coefficients between these variables and runoff BAP were generally lower than those for runoff SRP. Using these relationships and critical BAP levels for stream eutrophication, we found corresponding critical levels of soil Mehlich-III P and Olsen P (which should not be exceeded) to be 65 to 85 and 40 to 55 mg kg(-1), respectively. 相似文献
925.
926.
垃圾在流化床中燃烧的特性 总被引:6,自引:1,他引:5
在一台特别设计的小型流化床燃烧实验台上对垃圾可燃物代表组分进行实验研究 .结果表明 ,干燥的垃圾在床温仅为 50 0℃就能在很短的时间内迅速燃烧 ,产生明亮的火焰 .在本实验条件下 ,床温没有因为实验组分的加入而下降 ,而是随着垃圾的迅速燃烧而急剧升温 ,床温提高 30~ 70℃不等 .垃圾在流化床中燃烧受多种因素的影响 ,并讨论了当物料形状 (整或碎 )、含水量、实验风量 (从 5.5m3/h到 7.5m3/h)等因素变化后对于燃烧气体成分及炉内温度的影响 .在本实验条件下 ,当物料剪碎后会引起炉内温度水平明显提高 ,并使得CO排放量略有下降 .物料含水量增加时会导致炉内温度水平明显下降 .实验风量提高时 ,CO排放量明显减少 . 相似文献
927.
928.
对酵母菌处理色拉油加工废水的连续小试处理过程中出现的污泥膨胀进行了研究.根据鉴定,3属共5种酵母菌被用于连续小试处理(12 L曝气池).在进水COD 6000~7000 mg/L,油1500~1700 mg/L,污泥负荷1.2~3.2 kg COD/(kg MLSS(d)和0.2~0.9 kg油/(kg MLSS(d)时, COD和油的去除率分别在94%和98%以上,污泥发生膨胀后去除率明显下降,同时污泥中真菌丝逐渐替代假菌丝而成为优势形态.从膨胀污泥中分离鉴定出一株白地霉. 相似文献
929.
Combined amendment reduces soil Cd availability and rice Cd accumulation in three consecutive rice planting seasons 总被引:1,自引:0,他引:1
Wenjun Yang Shilong Wang Hang Zhou Min Zeng Jingyi Zhang Fang Huang Shiping Shan Zhaohui Guo Hongwei Yi Zhiguang Sun Jiaofeng Gu Bohan Liao 《环境科学学报(英文版)》2022,34(1):141-152
The scientific application of stabilized materials has been considered an effective method for the in situ remediation of Cd-contaminated soil. This study aimed to investigate the persistence of the effect of a combined amendment of limestone and sepiolite(LS) on soil Cd availability and accumulation in rice grown in a mildly Cd-contaminated paddy field(0.45 mg/kg of Cd) over three consecutive rice seasons. 1125–4500 kg/ha of LS was applied to the soil before the first rice planting season and 5... 相似文献
930.
施用农业生产中广泛使用的无机氮肥和有机肥,以花红苋菜为典型叶菜类蔬菜,研究了不同施肥方式对蔬菜吸收和积累土壤中多环芳烃(PAHs)的影响.结果表明,蔬菜根部积累的PAHs 总浓度显著大于其地上部分积累的浓度.有机肥处理下,低环PAHs 在蔬菜根中的生物富集因子(RCFs)显著小于其余处理的对应值,表明添加有机肥更有利于降低低环PAHs 的生物有效性.土壤低环PAHs 的RCFs 值显著大于高环PAHs 的RCFs 对应值.种植蔬菜后,根际土壤PAHs 的总浓度显著降低;有机肥处理比无机氮肥处理有利于根际土壤中PAHs 的消解. 相似文献