全文获取类型
收费全文 | 1025篇 |
免费 | 10篇 |
国内免费 | 35篇 |
专业分类
安全科学 | 50篇 |
废物处理 | 84篇 |
环保管理 | 93篇 |
综合类 | 90篇 |
基础理论 | 157篇 |
环境理论 | 1篇 |
污染及防治 | 386篇 |
评价与监测 | 147篇 |
社会与环境 | 52篇 |
灾害及防治 | 10篇 |
出版年
2023年 | 27篇 |
2022年 | 131篇 |
2021年 | 101篇 |
2020年 | 39篇 |
2019年 | 44篇 |
2018年 | 58篇 |
2017年 | 66篇 |
2016年 | 61篇 |
2015年 | 26篇 |
2014年 | 40篇 |
2013年 | 126篇 |
2012年 | 48篇 |
2011年 | 60篇 |
2010年 | 42篇 |
2009年 | 28篇 |
2008年 | 26篇 |
2007年 | 27篇 |
2006年 | 21篇 |
2005年 | 11篇 |
2004年 | 17篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1964年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有1070条查询结果,搜索用时 15 毫秒
981.
Aghamiri SM Ghorbani Z Darafsheh A Torabzadeh H Fathivand AA Minuchehr A Jalinoos A 《Journal of environmental radioactivity》2006,89(3):212-218
The level of natural radiation in some regions of Ramsar, a northern coastal city of Iran, is known to be among the highest levels of natural radiation in the world. 226Ra existing in high concentrations in the soil of this region is washed by underground water and transferred to the surface. In this way, 226Ra enters the food chain of residents and substitutes within the hard body tissues of humans. 226Ra is one of the so-called bone seekers as its metabolic processes in the human body are similar to calcium and remains in hard tissues of body because of its long half-life, and being an alpha emitter causes dangerous effects on human health. The purpose of this study is to determine the concentration of 226Ra in the teeth of residents of these high-level natural radiation areas, compared with a control group. Thirteen teeth in five groups were studied as the case group and thirteen teeth in five corresponding control groups were inspected. The mean values of the activity of 226Ra in the case group and in the control group were 0.32 and 0.18mBqg(-1), respectively. 相似文献
982.
Monsoon flooding occurred in the main areas of the Khyber Pakhtunkhwa, Punjab, and Balochistan as well as parts of Gilgit Baltistan of Pakistan and Azad Jammu Kashmir in July 2010. Water-borne diseases such as cholera, enteric fever, and dysentery were common among the inhabitants of flood-affected areas which were selected for sample collection. In the present study, 10 sites in District Peshawar were selected and drinking water samples collected. These samples were analyzed for the total plate count (TPC), total coliform bacteria (TCB), total fecal coliform bacteria (TFCB), Escherichia coli (EC), Pseudomonas aeruginosa (PA), Vibrio cholerae (VB), Salmonella Shigella, and Staphylococcus aureus. The TPC ranged from 8 × 101 to 7 × 104 CFU/ml. The TCB ranged from <1.1 to 280 MPN/100 ml. Twenty percent of the samples were contaminated with TFCB, EC, Salmonella, Shigella, and Staphylococcus aureus, while only one sample contaminated with PA. Forty percent of the samples were contaminated with VB. The surface and well water was greatly contaminated by flooding and major improvements on priority basis are essential. 相似文献
983.
In this study, the concentrations of Co, Ni, Fe, Cu, Mn, Pb, Cr, and Cd were determined in 15 cigarette brands from Turkey by flame atomic absorption spectrometry (FAAS). A wet digestion method was employed to cigarette samples. The mean values obtained for Co, Ni, Fe, Cu, Mn, Pb, Cr, and Cd were 1.2, 4.1, 134, 14, 66, 3.7, 5.0, and 1.1?µg?g?1, respectively, i.e., in the order of Fe?>?Mn?>?Cu?>?Cr?>?Ni?>?Pb?>?Co?>?Cd. The results were compared with the literature values for other international cigarette brands. 相似文献
984.
The purpose of this investigation was to determine the rate of generation of different kinds of hospital waste and its management in 11 provinces of Iran in 2012. Waste samples were separated into two categories (domestic type and infectious waste) and weighed daily for 4 weeks, distributed over four seasons to determine quantities and composition. Data on waste management were collected through a questionnaire and interviews of hospital personnel. The total generation of hospital waste ranged from 2.3 to 4.6 kg bed-day?1 for Razavi Khorasan and Sistan &; Baluchistan provinces. Generation of infectious waste varied from 1.0 to 1.7 kg bed-day?1 for Sistan &; Baluchistan and Markazi provinces. The lowest and highest percentages of infectious waste generation were found in Golistan (3.8%) and Fars (15.3%). It was also revealed that management of sharps, infectious, and other hazardous wastes was not properly done. A segregation program must be implemented and each fraction of hospital waste must be collected and disposed of separately. 相似文献
985.
The effects of deltamethrin on the histology of Oreochromis niloticus testis and ovary and the protective effect of vitamin E supplementation were investigated. The fish were divided into four groups, i.e. a control group, a vitamin-E-treated group, a deltamethrin-treated group and a vitamin E+deltamethrin-treated group. In the control and vitamin-E-treated groups, the ovaries and testes were normal at the end of 7, 14, and 21 days. In the deltamethrin-treated group, deformed oocytes, atretic oocytes, melanomacrophage centers, and focal necrotic areas were noted in the ovaries. Deltamethrin also caused cell necrosis, nuclear pycnosis, decreasing number of spermatogenic cells, decreasing spermatozoa within the lumen of tubule, decreasing number of spermatocyte cells, hypertrophy and degeneration of spermatogonia cells, and increasing number of macrophages in testis. Vitamin E decreased some histopathological changes induced by deltamethrin, but did not confer complete protection. 相似文献
986.
The present investigation was carried out to examine the cytotoxic and genotoxic effects of a Tinospora cordifolia crude methanolic extract (palmatine) on human skin epithelial carcinoma cells (A431). T. cordifolia is one of the indispensable medicinal plants used in Ayurvedic medicine for treatment of various diseases and recommended for improving the immune system. Cytotoxicity and genotoxicity evaluation was carried out using A431 cells treated with different concentrations of palmatine. The duration of the treatment was 24 and 48 hr. A cellular proliferative capacity test showed that palmatine produced cytotoxicity in concentration- and time-dependent manner. Further, palmatine induced significant intracellular reactive oxygen species generation and elevated lipid peroxidation, as well as activities of catalase and superoxide dismutase. DNA fragmentation analysis using the comet assay showed that palmatine induced genotoxicity in a concentration- and time-dependent manner. Evidence indicates palmatine is capable of induction of oxidative stress resulting in cell death and genomic instability. 相似文献
987.
Sediment bulk parameters and fatty acid biomarkers were used to investigate the relative contribution of major sources of particulate organic matter during upwelling and non-upwelling conditions, at organic enriched sites on the south-eastern Brazilian coast. The degradation state of the organic material and its implications for benthic food webs were also evaluated. Temperature and salinity values indicate the intrusion of the South Atlantic Central Water in spring with a strong influence at station 4S. C:N ratios and fatty acid biomarkers suggest that sedimentary particulate organic matter is mainly autochthonous and originated from phytoplankton, zooplankton and bacteria, with a minor terrestrial contribution. Short-chain saturated fatty acids predominated, indicating the prevalence of partially degraded detritus. An exception was station 4S, where polyunsaturated fatty acids dominated, indicating the input of labile organic matter linked to upwelling of the South Atlantic Central Water. Fatty acid concentrations and the organic carbon content of the sediments suggest that food quantity is not a limiting factor for benthic fauna. Despite the high organic background of the sediments, the sporadic inputs of labile organic matter associated with South Atlantic Central Water intrusions may produce an important impact on benthic fauna and on the biogeochemistry of the sediments. 相似文献
988.
The development of reliable, accessible, and transparent earthquake early warning systems (EEWSs) for disaster reduction have been given increased priority at local, national, and international levels. Accurately quantifying the social and economic benefits accrued to households and businesses from EEWSs are a challenging and difficult task. In this paper, the Contingent Valuation Method (CVM) is used to evaluate the benefits of a hypothetical EEWS to the citizens of Tehran Metropolitan. This study clarifies public willingness to pay (WTP) for EEWS in Tehran, and the dominant factors involved in WTP through a CVM analysis. The survey, completed by more than 504 households, showed that on average households are willing to pay 367,471 Rials (~38 US$) per month for the hypothetical EEWS. Those willing to pay the most for EEWS are households, which currently possess a fire alarm. Also the more educated the respondents and the more children the respondents have, the more willing they are to pay for EEWS. These results could be used by policy makers and technology firms in order to determine the optimal investments in early warning systems for earthquake disaster reduction. 相似文献
989.
Ishaque AB Bass EL Jesien R Hughes S Hupke C 《Journal of environmental biology / Academy of Environmental Biology, India》2005,26(1):1-5
Vitellogenin (vtg) concentrations were measured in plasma and liver samples from 12 hybrid Tilapia oreochromis niloticus x O. aureus to compare concentrations in these tissues. The results were calculated under two different normalizations: volume per gram of sample used (similar to normalization usually published in the literature and typically used for ELISA) and volume per total protein (similar to normalization used in polyacrylamide gel electrophoresis; PAGE). It was observed that the normalization procedure used in PAGE (per gram total protein) minimized the method detection limit by about 1000 and 2500 times in plasma and liver respectively, compared to the normalization usually reported in the literature. It was also observed that normalizing per gram total protein makes it possible to eliminate a potential problem of accidental dilution of plasma samples during sample collection. Moreover, the normalization on a per gram of total protein makes it possible even to compare results from the two different methods namely PAGE and ELISA. It also allows comparison between different tissues. Using the normalization procedures as used in PAGE (per gram total protein) for liver and the normalization method as reported in literature for ELISA (per volume of sample used), it was observed that liver samples had higher vtg levels (mean: 62 microg vtg/g) compared to the corresponding plasma samples (mean: 0.24 microg vtg/ml). However, when both results were normalized per gram total protein all but one liver sample were lower (62 microg vtg/g) than the corresponding plasma concentrations (mean = 246 microg vtg/g). 相似文献
990.
The results of epidemiological studies in various countries show that radon and its progeny cause carcinogenic effects on mine workers. Therefore, it becomes of paramount importance to monitor radon concentrations and consequently determine the radon dose rates in coal mines for the protection of coal miners. A new calibration curve was obtained for radon concentration estimation using hybrid techniques. A calibration curve was generated using 226Ra activity concentration measured by a HPGe detector-based gamma-ray spectrometer versus alpha-track-density rate due to radon and its progeny on CR-39 track detector. Using the slope of the experimentally determined curve in the units of Becqueral per kilogram (Bq kg-1) per unit alpha-track-density per hour (cm-2 h-1), radon concentrations (Bq m-3) were estimated using coal samples from various coal mines in two provinces of Pakistan, Punjab and Balochistan. Consequently, radon dose rates were computed in the simulated environment of the coal mines. Results of these computations may be considered with a caveat that the method developed in this paper provides only a screening method to indicate the radon dose in coal mines. It has been shown that the actual measurements of radon concentrations in the coal mines are in agreement with the estimated radon concentrations using the hybrid-technique calibration curve. 相似文献