全文获取类型
收费全文 | 5242篇 |
免费 | 389篇 |
国内免费 | 1928篇 |
专业分类
安全科学 | 100篇 |
废物处理 | 202篇 |
环保管理 | 745篇 |
综合类 | 3529篇 |
基础理论 | 2021篇 |
环境理论 | 2篇 |
污染及防治 | 406篇 |
评价与监测 | 278篇 |
社会与环境 | 169篇 |
灾害及防治 | 107篇 |
出版年
2024年 | 6篇 |
2023年 | 19篇 |
2022年 | 69篇 |
2021年 | 44篇 |
2020年 | 29篇 |
2019年 | 33篇 |
2018年 | 41篇 |
2017年 | 54篇 |
2016年 | 39篇 |
2015年 | 51篇 |
2014年 | 97篇 |
2013年 | 295篇 |
2012年 | 245篇 |
2011年 | 120篇 |
2010年 | 127篇 |
2009年 | 132篇 |
2008年 | 109篇 |
2007年 | 277篇 |
2006年 | 291篇 |
2005年 | 233篇 |
2004年 | 178篇 |
2003年 | 213篇 |
2002年 | 273篇 |
2001年 | 289篇 |
2000年 | 435篇 |
1999年 | 509篇 |
1998年 | 395篇 |
1997年 | 398篇 |
1996年 | 486篇 |
1995年 | 399篇 |
1994年 | 354篇 |
1993年 | 251篇 |
1992年 | 173篇 |
1991年 | 210篇 |
1990年 | 133篇 |
1989年 | 95篇 |
1988年 | 64篇 |
1987年 | 65篇 |
1986年 | 33篇 |
1985年 | 33篇 |
1984年 | 73篇 |
1983年 | 52篇 |
1982年 | 26篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1977年 | 7篇 |
1976年 | 27篇 |
1975年 | 33篇 |
1974年 | 11篇 |
排序方式: 共有7559条查询结果,搜索用时 15 毫秒
951.
K.M.S. Sundaram A. Sundaram B.D. Hammock 《Journal of environmental science and health. Part. B》2013,48(5):999-1052
Abstract A commercial formulation of Bacillus thuringiensis Berliner var. kurstaki (BTK), Foray® 48B, was sprayed aerially over four blocks B13, B14, B15A and B15B in an oak forest in Wayne County, Pennsylvania during May 1990. B13 and B14 were sprayed at 75 billion international units (BIU) in 5.91 litres/ha and the other two at 50 BIU in 3.94 litres/ha. Oak foliage was collected at different intervals of time after treatment. Three types of bioassays were conducted against fourth instar gypsy moth larvae, viz., direct feeding of sprayed foliage, feeding on diet containing homogenized foliage, and force‐feeding of foliar extracts. Larval mortalities were converted into international units of BTK activity per unit area (IU/cm2) of foliage. Foliar extracts were also subjected to enzyme‐linked immunosorbent assay (ELISA) to determine the concentration of delta‐endotoxin protein. Regardless of the type of bioassay used, bioactivity of BTK persisted in foliage for about a week in all the blocks. The half‐life of inactivation, DT50, ranged from ca 12 to 22 h. The immunoassay data indicated a shorter duration of persistence (i.e., about 2 d) of the delta‐endotoxin protein, with DT50 values ranging from 10 to 15 h. Formulation ingredients present in Foray 48B played a role in the toxicity of BTK to gypsy moth larvae. 相似文献
952.
RAIMON GUITART RAQUEL CLAVERO RAFAEL MATEO MANUEL MÁÑEZ 《Journal of environmental science and health. Part. B》2013,48(5):753-760
Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) residue levels were determined in 53 unhatched eggs from greater roseus flamingos (Phoenicopterus ruber). Eggs were collected in 1996 from the National Park of Doñana (Guadalquivir marshes, Southwest Spain), immediately after one breeding colony abandoned the nesting site due to predator attacks. The main metabolite of p,p′-DDT, p,p′-DDE, was the OCP residue found at higher concentrations, with a geometric mean of 721 ng/g wet weight. Residues of other pesticides, including some hexachlorocyclohexane isomers, hexachlorobenzene, aldrin, heptachlor, and heptachlor-epoxide, were detected at much lower concentrations. The sum of PCBs was 528 ng/g, with PCB congeners #187 and #153 being the most prominent in eggs. The pattern observed in these compounds of industrial origin corresponded more to Aroclor 1260 than to any other commercial mixture. Levels of organochlorine residues indicate a medium degree of exposure, and they are not considered of any concern for the flamingo population. In particular, neither p,p′-DDE nor PCB levels were found to be correlated with the eggshell thickness. 相似文献
953.
GEORGE F. ANTONIOUS TEJINDER S. KOCHHAR ROBERT L. JARRET JOHN C. SNYDER 《Journal of environmental science and health. Part. B》2013,48(7):1237-1243
The U.S. Department of Agriculture (USDA) pepper (Capsicum spp.) germplasm collection contains several thousand members or accessions. Many of these species and cultivars have not been analyzed for their concentrations of ascorbic acid, capsaicin, and total phenolic compounds, which are important antioxidants having a number of benefits for human health. The objective of this investigation was to select candidate accessions of hot pepper having high concentrations of ascorbic acid, capsaicin, free sugars, and total phenols for use as parents in breeding for these compounds. Seventeen accessions of pepper from the core Capsicum germplasm collection (four accessions of Capsicum chinense; five accessions of C. baccatum; six accessions of C. annuum; and two of C. frutescens) were field grown and their mature fruits were analyzed for their antioxidant composition. Concentrations of these compounds tended to be higher in C. chinense and C. baccatum, than in C. annuum and C. frutescens. Across all accessions the concentration of total phenols was correlated with ascorbic acid (r = 0.97) and free sugars (r = 0.80). Concentrations of total phenols (1.4, 1.3, and 1.3 mg g?1 fruit) and ascorbic acid (1.6, 1.2, and 1.3 mg g?1 fruit) were significantly greater in PI-633757, PI-387833, and PI-633754, respectively, compared to other accessions analyzed. Total capsaicinoids concentrations were greatest (1.3 mg g?1 fruit) in PI-438622 and lowest (0.002 mg g?1 fruit) in Grif-9320. The great variability within and among Capsicum species for these phytochemicals suggests that these selected accessions may be useful as parents in hybridization programs to produce fruits with value-added traits. 相似文献
954.
Ting Xu Bao M. Wang Wei Sheng Qing X. Li Xiao L. Shao Ji Li 《Journal of environmental science and health. Part. B》2013,48(2):173-177
The present study outlines applications of an enzyme-linked immunosorbent assay (ELISA) for the analysis of clenbuterol residues. Antisera were raised from rabbits immunized with diazotized clenbuterol-bovine serum albumin (BSA) conjugate. The assay was specific to clenbuterol with a half-maximum inhibition concentration (IC50) of 1.8 ng/mL and 2.5 ng/mL in blank swine urine and phosphate buffer solution, respectively. The assay had high cross-reactivity (86%) with mabuterol, but low with other adrenergic agonists and antagonists. The average recovery of clenbuterol, as measured with the ELISA, ranged from 90% to 112% in swine urine samples and from 86% to 95% in feeds, respectively. This new assay was compared with commercial ELISA test kits. An excellent correlation (r 2 = 0.98) between the two methods and satisfactory recoveries suggest that the new assay can be suitable for the determination of clenbuterol residues in real samples. The assay was used to analyze clenbuterol residues in 103 swine urine samples and 68 feed samples collected from northern China. Approximately 50% of the urine samples and 25% of the feed samples analyzed were found positive (concentration of clenbuterol ≥ 1 ppb). The results indicate that clenbuterol was misused in some of the areas surveyed. 相似文献
955.
A.H. El‐Sebae E.E. Enan S.A. Soliman S. El‐Fiki E. Khamees 《Journal of environmental science and health. Part. B》2013,48(4):475-491
Abstract The three S‐n‐propyl phosphates and phosphothioates: RH 218, profenofos and prothiophos were compared with fenitrothion in their potential as inhibitors of rat liver and brain AChE. Fenitrothion was more potent as an inhibitor than the three S‐n‐propyl derivatives. Incubation of hepatic protein enhanced ChE inhibition in brain in the case of fenitrothion, while it reduced the inhibitory effect of the S‐n‐propyl derivatives. On the other hand, the four organophosphorus esters caused hypoglycemia in both male and female rats and also reduced their blood urea with different degrees. 相似文献
956.
Photoreduction characteristics of divalent inorganic mercury(Hg~(2+)) in the presence of specific algae species are still not well known. Laboratory experiments were conducted in the present study to identify the effects of different concentrations of living/dead algae species, including Aphanizomenon flosaquae(AF) and Microcystis aeruginosa(MA), on the photoreduction rate of Hg~(2+)under various light conditions. The experimental results showed that percentage reduction of Hg~(2+)was significantly influenced by radiation wavelengths, and dramatically decreased with the presence of algae. The highest percentage reduction of Hg~(2+)was induced by UV-A, followed by UV-B, visible light and dark for both living and dead AF, and the order was dark UV-A UV-B visible light for both living and dead MA. There were two aspects, i.e., energy and attenuation rate of light radiation and excrementitious generated from algae metabolisms, were involved in the processes of Hg~(2+)photoreduction with the presence of algae under different light conditions. The percentage reduction of Hg~(2+)decreased from 15% to 11% when living and dead AF concentrations increased by 10 times(from 106 to 105 cells/mL), and decreased from 11% to ~ 9% in the case of living and dead MA increased. Algae can adsorb Hg~(2+)and decrease the concentration of free Hg~(2+), thus inhibiting Hg~(2+)photoreduction, especially under the conditions with high concentrations of algae. No significant differences were found in percentage reduction of Hg~(2+)between living and dead treatments of algae species.The results are of great importance for understanding the role of algae in Hg~(2+)photoreduction. 相似文献
957.
针对城市河道治理后反复出现水华现象的问题,以上海市青浦区小涞港河段为研究区域,基于层次分析法和熵权法的组合赋权法,参考相关研究并结合实地调查,优化选取水质、底泥、护岸等相关指标建立评价指标体系,进行河道生态修复效果评价。结果表明:较高的硝酸盐浓度〔NO3 −-N浓度为(3.055±2.863)mg/L,其与叶绿素a浓度显著相关,
958.
Geomorphologically appropriate rehabilitation measures were proposed to enhance the in-stream environment of the lowland River Idle, north Nottinghamshire, UK. However, the River Idle has multi-functional management requirements including those of flood defence so environmental enhancement must be pursued without significantly increasing the flood risk. Hydraulic testing of rehabilitation proposals is complicated because of the stringent assumptions about flow and morphology in ‘traditional’ hydraulic models. While new generation two- and three-dimension hydraulic models may overcome some of these problems, they are extremely data intensive, require advanced modelling capabilities and are, therefore, very expensive to apply. Also, they do not yet predict morphology-flow interactions adequately. As an alternative, several simple hydraulic models were applied to test the rehabilitation proposals, based on a fitness-for-purpose criterion.BENDFLOW was applied to fine tune the optimal siting of measures and to estimate the additional near-bank scour generated by proposed bend re-profiling. HMODEL2 and the FCFA method were used to test the impact on local channel conveyance capacities and HECRAS was applied to simulate the impact of the proposals on regional flood defence. Indicative results from the testing suggested a maximum increase in near-bank scour of 0·15 m in re-profiled bends, a loss of approximately 10% in flood conveyance locally due to deflector installation or reed and tree planting, and a 0·12 m increase in flood stage within the reach for a 15 year flood. The modelling results were acceptable to the management authority as an indication of an acceptable compromise between flood defence and conservation interests, and construction of the measures followed in 1996. It is clearly that it will require the results of post-project monitoring to indicate whether compromises made to the rehabilitation initiatives in order to satisfy flood defence requirements have unduly reduced their environmental enhancement potential but, for assessing the proposed methods, the models are recommended for use other lowland river environments. 相似文献
959.
960.