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101.
Han I Mihalic JN Ramos-Bonilla JP Rule AM Polyak LM Peng RD Geyh AS Breysse PN 《Journal of the Air & Waste Management Association (1995)》2012,62(7):773-782
The main objectives of this study are to (1) characterize chemical constituents of particulate matter (PM) and (2) compare overall differences in PM collected from eight US. counties. This project was undertaken as a part of a larger research program conducted by the Johns Hopkins Particulate Matter Research Center (JHPMRC). The goal of the JHPMRC is to explore the relationship between health effects and exposure to ambient PM of differing composition. The JHPMRC collected weekly filter-based ambient fine particle samples from eight US. counties between January 2008 and January 2010. Each sampling effort consisted of a 5-6-week sampling period. Filters were analyzed for 25 metals using inductively coupled plasma mass spectrometry (ICP-MS). Overall compositional differences were ranked by principal component analysis (PCA). The results showed that weekly concentrations of each element varied 3-40 times between the eight counties. PCA showed that the first five principal components explained 85% of the total variance. The authors found significant overall compositional differences in PM as the average of standardized principal component scores differed between the counties. These findings demonstrate PCA is a useful tool to identify the differences in PM compositional mixtures by county. These differences will be helpful for epidemiological and toxicological studies to help explain why health risks associated with PM exposure are different in locations with similar mass concentrations of PM. 相似文献
102.
Sulfamethoxazole sorption by sediment fractions in comparison to pyrene and bisphenol A 总被引:5,自引:0,他引:5
Juan Hou Xuekui Niu Baoshan Xing 《Environmental pollution (Barking, Essex : 1987)》2010,158(9):2826-2832
The environmental behavior of antibiotics has attracted great research attention. However, their sorption mechanisms in soils/sediments are still unknown. Comparison of the sorption properties between the widely-studied hydrophobic organic contaminants (HOCs) and antibiotics may provide valuable insight to antibiotic sorption mechanisms. Thus, in this study batch experiments for pyrene (PYR), bisphenol A (BPA), and sulfamethoxazole (SMX) sorption were conducted on a sediment sample and its separated fractions. Our results showed the high sorption of PYR on black carbon and organic matter. Although high sorption of SMX was observed for both separated organic fractions (humic acids) and inorganic mineral particles, the original sediment particles showed relatively low sorption. Competitive sorption between SMX and dissolved humic acid on mineral particles was observed in this study. This competitive interaction is a unique process for antibiotic sorption in soils/sediments compared with apolar HOCs and may be one of the important factors controlling the antibiotic sorption. 相似文献
103.
104.
研究了有机高分子絮凝剂NCTS-M对中性兰染料的絮凝性能。通过测量絮体的Zeta电位以及对絮体进行彩色电视显微扫描初步探讨了该絮凝过程的絮凝机理。结果表明,当投加量为30 mg/L,pH=6时,絮凝效果最明显,脱色率可达93.1%。其絮凝机理主要是压缩双电层以及高分子吸附架桥作用,以压缩双电层为基础。絮凝剂中镁离子在中性条件下对絮凝过程也起到了较强的助凝作用。 相似文献
105.
Jesús M. Avilés Deseada Parejo Tomás Pérez-Contreras Carlos Navarro Juan J. Soler 《Die Naturwissenschaften》2010,97(2):181-186
A considerable number of bird species carry feathers to their nests. Feathers’ presence in the nests has traditionally been
explained by their insulating properties. Recently, however, it has been suggested that feathers carried to the nests by females
of the spotted starling (Sturnus unicolor L.) could have an ornamental function based on their ultraviolet (300–400 nm) and human-visible longer wavelength (400–700 nm)
coloration. In our population, 95.7% of feathers found inside next-boxes occupied by nesting starlings were rock dove fly
feathers. Of these feathers, 82.7% were naturally positioned with their reverse side oriented toward the entrance hole and
42.4% of all found feathers were situated within the nest-cup. Here we experimentally assess the signaling function of ultraviolet
coloration of feathers in nests of spotless starlings by providing nests with a number of pigeon flight feathers that were
respectively treated on their obverse, reverse, both, or neither side with a UV blocker. Starlings placed 42.5% of the experimental
feathers in the nest-cup irrespective of the UV block treatment. Orientation of feathers toward the entrance hole was not
related with their ultraviolet radiation. However, feathers placed within the nest-cup were more likely found with their reverse
side oriented toward the entrance hole confirming our correlative findings. These results suggest a minor role of ultraviolet
coloration on feather location by spotless starlings. 相似文献
106.
107.
尾矿资源化利用的问题、条件及相关政策建议 总被引:1,自引:0,他引:1
我国是矿产资源生产和消费大国.由于我国矿产资源的特点是单一大型矿床少、共伴生和贫矿难选矿多、矿石自然品位较低等,加上采选技术、加工技术及设备落后等原因,矿产资源回收率低、单位矿产品的废弃物产生量大,造成我国可利用的资源不足等问题,所以尾矿资源的利用显得十分必要和迫切,但尾矿的利用必须以经济可行且对环境不造成二次污染为前提.论述了尾矿资源化利用必须解决的问题,并就尾矿资源化利用提出了相关政策建议. 相似文献
108.
在考虑吸附与脱附作用的基础上提出了室内毒物浓度的计算方法,利用剂量响应模型进行中毒定量评估.分别对纯净物、混合物的中毒定量评估方法进行阐述,并举例计算分析各种情况下概率变量达到半数致死的时间.研究结果可以指导室内车间毒性准则的制定. 相似文献
109.
目的研究不同时间下锌在SO2环境中的腐蚀特性。方法采用室内加速试验法,向大气加速腐蚀箱中通入25 mg/L SO2气体,进行模拟工业大气环境下的加速腐蚀试验。对腐蚀后金属材料进行质量增量测量和电化学测试,通过XRD,SEM等表征锌腐蚀产物及腐蚀形貌,研究腐蚀特性。结果初期阶段锌在SO2环境中的腐蚀速率逐渐增加,到腐蚀后期逐渐降低,1/Rct值先增大后减小,锌的腐蚀产物中的元素包括Zn,O和少量的S,主要产物为Zn4SO4(OH)6。结论初期在锌表面生成的腐蚀产物疏松,SO2能够通过产物层到达基体,促进腐蚀,不具有保护性。到后期,产物增多并且致密使SO2与基体接触的概率降低,从而使腐蚀速率减缓。 相似文献
110.
Murillo-Acevedo Yesid S. Giraldo Liliana Poon Po S. Matos Juan Moreno-Piraján Juan C. 《Environmental science and pollution research international》2021,28(6):6746-6757
Environmental Science and Pollution Research - A linear algebra theorem like Cramer’s rule was used for the analysis of a system of equations obtained from UV spectroscopy, and results were... 相似文献