全文获取类型
收费全文 | 123篇 |
免费 | 13篇 |
国内免费 | 27篇 |
专业分类
大气科学 | 9篇 |
地球物理 | 43篇 |
地质学 | 53篇 |
海洋学 | 44篇 |
综合类 | 6篇 |
自然地理 | 8篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 14篇 |
2005年 | 13篇 |
2004年 | 10篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有163条查询结果,搜索用时 31 毫秒
21.
A long-term programme for monitoring toxic substances in the marine environment was established in Hong Kong in 2004, focusing on chemicals of potential ecological and health concern. The programme ran on 3-year cycles, with the first two years monitoring marine water, sediment, biota, and the third year monitoring pollution sources. Twenty-four priority chemicals were measured, including dioxins/furans, dioxin-like PCBs, total PCBs, PAHs, DDTs, HCHs, TBTs, phenol, nonylphenol (NP), NP ethoxylates, PBDEs and metals. Results from the first three years of monitoring indicate that toxic substances in the Hong Kong marine environment were within the range reported for the coastal waters in China and other regions, but generally lower than in the Pearl River Estuary. The levels met the standards for protecting aquatic life and human consumption. Sewage effluent, stormwater and river water were possible sources of phenolic compounds; whereas air deposition or regional pollution, rather than local discharges, may contribute to the dioxins/furans, PAHs and PCBs found in the marine environment. 相似文献
22.
Priyanka Lal Vishnu Agarwal Parul Pruthi Swaranjit Singh Cameotra Vikas Pruthi 《洁净——土壤、空气、水》2008,36(12):963-968
The microbiological assessment of biofilm formation from paper mill effluent discharged through a pipeline revealed a maximum microbial count for Pseudomonas (5·106 cfu/mL) followed by Staphylococcus (4·106 cfu/mL), Bacillus (8.2·105 cfu/mL), Burkholderia (7.2·105 cfu/mL), Enterobacter (5.3·104 cfu/mL), Acinetobacter (4.1·103 cfu/mL), Alcaligenes (1.2·102 cfu/mL) and Klebsiella (0.8·102 cfu/mL) species. Among these species, the maximum biofilm formation was observed after 24 h of incubation by Pseudomonas sp. using a crystal violet (CV) assay. This isolate was later identified by 16S rRNA amplification to be Pseudomonas aeruginosa PME1. Extracellular polymeric substances (EPS) of P. aeruginosa PME1 in the biofilm showed a reduction in total carbohydrate content (42%) with increased protein (9.0%), hexosamine (3.0%) and uronic acid (1.7%) content as compared to its planktonic form. Antimicrobial susceptibility testing revealed that P. aeruginosa PME1 biofilms were 17, 24, 27, 30, and 32 times more resistant to cefotaxime, imipenem, ceftazidime, tazobactam and piperacillin, respectively, than their free flowing counterparts. 相似文献
23.
1IntroductionDuringthe past several years,concern hasincreasedover the potential pollution of watershed by estrogeniccompounds,including steroidal hormones fromhumanand ani mal sources.Effluents from wastewater treat-ment plants are sources of endocrine-d… 相似文献
24.
运用3DEEMs及荧光偏振方法研究pH、离子强度及浓度效应对腐殖酸荧光光谱特性的影响 总被引:6,自引:0,他引:6
利用三维荧光激发.发射光谱(3DEEMs)及荧光偏振法研究了3例腐殖酸和1例湖泊溶解有机物(DOM)在不同腐殖酸浓度、离子强度和pH条件下的荧光光谱特性.实验结果表明,随着浓度增大,各腐殖酸样的荧光强度增大,其中垃圾渗滤液腐殖酸和Pahokee泥炭腐殖酸的荧光峰出现红移.随着浓度进一步增大,腐殖酸的荧光偏振值增大,由此推断在此浓度范围内腐殖酸由于分子间的排斥作用使其构型出现伸展.离子强度增大导致腐殖酸及阿哈湖DOM的荧光强度降低.随着氯化钾(KCI)浓度增大,Fluka腐殖酸的荧光峰A蓝移,荧光峰B的荧光偏振值出现减小,推测是由于静电中和作用使其荧光基团发生卷曲造成的.离子强度对其余腐殖酸样和阿哈湖DOM的其他荧光特性没有明显的影响.总的来说,pH值的变化对腐殖酸和湖泊DOM的荧光特征的影响是很明显的.随着pH值增大,腐殖酸和湖泊DOM的荧光强度增强.而pH值减小时,Fluka腐殖酸和Pahokee泥炭腐殖酸的荧光峰(A峰)蓝移,当pH值降到5时,Fhka腐殖酸的荧光峰突然红移到最大,随后又继续蓝移;垃圾渗滤液腐殖酸和阿哈湖DOM的荧光峰位无明显的漂移.所有样品的荧光偏振值都减小(但阿哈湖DOM的A峰变化不大),但在pHi≤5时又增大,这种现象表明随着pH值降低,腐殖酸和湖泊DOM中有机大分子发生卷曲,但在pH≤5时由于羧基的质子化又以平面伸展构型出现在溶液中. 相似文献
25.
实验室条件下微生物降解原油的地球化学特征研究 总被引:11,自引:2,他引:11
通过对胜利油田四个正常原油样品微生物作用前后的族组分及饱和烃色谱质谱分析,发现实验室条件下微生物对原油有明显的降解作用。微生物作用以后的原油族组分其饱和烃相对含量降低,饱/芳比也明显降低,而芳烃、非烃和沥青质的相对含量都不同程度的升高。通过饱和烃色谱-质谱分析,发现微生物作用以后原油正构烷烃被严重降解,姥/植(Pr/Ph)比值和∑C21-/∑C22+比值都明显降低。微生物作用原油后能产生表面活性剂,造成了培养基表面张力的降低。 相似文献
26.
27.
本文总结了地面上铁磁性物质感应磁场现场测量结果,较详细地描述其感应磁场的分布特征。它对地磁台站的建设与环境保护,分析与排除人为干扰因素有一定的参考意义。文中还分析菏泽地震遥测传输铁塔对地磁观测的干扰情况。结果认为,该铁塔的感应磁场没有影响到地磁观测台。 相似文献
28.
In order to investigate the photobleaching potential of estuarine waters from different depths and redox conditions and with varying degree of biological activity, filtered, unfiltered and chloroform-poisoned water samples from the Baltic Sea were exposed to ambient sunlight. Fluorescence, at excitation 350 nm and emission 450 nm, was used as an indication of humic substance concentration. Fluorescence and organic carbon concentration were measured at regular time intervals during light exposure. We found that the decrease in humic substance fluorescence can be fitted to an exponential decay function. The fluorescence half-lives were within the range 0.4 – 4.6 days in different water masses, with fluorescence decreasing to between 20% and 60% of initial concentration, respectively. Results from the curve fitting procedure indicate a rest concentration of humic substance fluorescence, similar among the sampled sites, that is resistant to further photochemical degradation. The largest relative decreases in fluorescence were found in deep waters, but samples from deep waters also had a higher fluorescence rest concentration than samples from surface waters. Biological activity was reduced by filtering the samples through 0.2μm pore size filters or adding chloroform. No statistically significant differences were found after 3 days of irradiation between samples with and without treatment to reduce biological activity. The highest initial fluorescence values and the largest fluorescence decrease were found in the anoxic waters of the Gotland Deep. The organic carbon concentrations decreased 3–7% at all stations. The shortest half-life of humic substance, and the largest decrease in organic carbon concentrations, were found in samples from the northern basins of the Baltic Sea. 相似文献
29.
Naduvilaveettil Sukumaran Kalesh Chenycherri House Sujatha S. Muraleedharan Nair 《Journal of Oceanography》2001,57(1):29-36
Information on the distribution of dissolved Folin phenol active substances (FPAS) such as tannin and lignin in the seawater along the west coast of India is provided. Notable amounts of FPAS (surface concentrations: 80 g/l to 147 g/l and bottom concentrations: 80 g/l to 116 g/l) were detected in the seawater along the coast. The distribution pattern brings about a general depth-wise decrease. A seaward decrease was observed in the southern stations whereas reverse was the case in northern stations. A significant negative correlation was observed between FPAS concentration and dissolved oxygen in sub-surface samples. The appreciable amounts of FPAS detected in the coastal waters indicate the presence of organic matter principally originating from terrestrial (upland and coastal marsh) ecosystems in the marine environment. In this context, they may be used as tracers to determine the fate of coastalborn dissolved organic matter in the ocean and to determine directly the relationship between allochthonous and autochthonous organic matter. 相似文献
30.