全文获取类型
收费全文 | 2579篇 |
免费 | 288篇 |
国内免费 | 1297篇 |
专业分类
安全科学 | 137篇 |
废物处理 | 319篇 |
环保管理 | 164篇 |
综合类 | 2158篇 |
基础理论 | 633篇 |
污染及防治 | 545篇 |
评价与监测 | 176篇 |
社会与环境 | 21篇 |
灾害及防治 | 11篇 |
出版年
2024年 | 5篇 |
2023年 | 35篇 |
2022年 | 60篇 |
2021年 | 83篇 |
2020年 | 91篇 |
2019年 | 83篇 |
2018年 | 97篇 |
2017年 | 117篇 |
2016年 | 143篇 |
2015年 | 171篇 |
2014年 | 180篇 |
2013年 | 297篇 |
2012年 | 252篇 |
2011年 | 238篇 |
2010年 | 195篇 |
2009年 | 190篇 |
2008年 | 167篇 |
2007年 | 227篇 |
2006年 | 212篇 |
2005年 | 163篇 |
2004年 | 135篇 |
2003年 | 131篇 |
2002年 | 122篇 |
2001年 | 93篇 |
2000年 | 89篇 |
1999年 | 94篇 |
1998年 | 94篇 |
1997年 | 71篇 |
1996年 | 66篇 |
1995年 | 53篇 |
1994年 | 35篇 |
1993年 | 25篇 |
1992年 | 37篇 |
1991年 | 40篇 |
1990年 | 17篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有4164条查询结果,搜索用时 78 毫秒
371.
氧化亚铁硫杆菌(A.ferrooxidans)介导的生物矿化方法可促使酸性矿山废水(Acid Mine Drainage,AMD)中Fe离子向次生铁矿物转变. 采用固定化的方式来提高A.ferrooxidans密度有助于强化Fe2+的生物矿化能力.选取流化床19孔填料、弹性填料、悬浮球填料作为挂膜对象, 通过多批次的连续培养来考察3种填料的A.ferrooxidans挂膜能力及稳定挂膜所需周期,继而比较3种挂膜填料对模拟AMD中Fe2+的生物矿化能力,并估算A.ferrooxidans有效生物量.结果表明,3种填料(5.00 g)的A.ferrooxidans挂膜能力依次为弹性填料(1.76 g)>流化床19孔填料(0.90 g)>悬浮球填料(0.78 g)(干重),且挂膜启动至稳定状态至少需要4批次.X射线衍射分析(X-ray diffraction,XRD)表明,3种填料表面 含矿生物膜均为施氏矿物和黄钾铁矾的混合物.以游离态A.ferrooxidans的Fe2+氧化速率作为参比,估算出流化床19孔填料、弹性填料、悬浮球填料生物膜中A.ferrooxidans有效生物量依次为1.67×108、8.52×108、1.92×108 cells·g-1 (干基).研究还发现,等同Fe2+生物氧化速率下, A.ferrooxidans挂膜填料比游离态A.ferrooxidans具有更强的AMD矿化驱动能力. 相似文献
372.
为评价多金属矿山废渣堆场生态修复过程中,废渣在先锋修复植物根系分泌的机酸参与下浸出液对周边环境生物的影响.以斑马鱼(Danio rerio)为受试生物,通过模拟添加典型先锋植物(黑麦草)根系分泌的有机酸(草酸和酒石酸)处理贵州威宁土法炼锌废渣,以废渣浸出液对受试生物抗氧化酶和乙酰胆碱酯酶(AchE)的不同响应为评价指标,研究各处理组对斑马鱼抗氧化系统、神经系统及组织学的影响.结果表明,两种有机酸的参与均会不同程度地降低炼锌废渣浸出液的pH,并导致废渣释放出更多重金属;暴露于有机酸参与的废渣浸出液14 d后,受试生物组织中的抗氧化酶受到显著影响,并因无法克服长时间的氧化应激最终引起丙二醇(MDA)在组织中累积;有机酸参与下废渣浸出液对斑马鱼具有明显的神经毒性,长时间暴露后受试生物出现游动迟缓、呼吸慢和鳃盖张合频率降低的现象;鳃组织存在上皮细胞水肿、增生或脱落、鳃丝充血和鳃小片扭曲或断裂的现象,而肌肉组织中出现更多肌纤维核增大、固缩和碎裂的现象.综上,选用适生性和耐受性较强、根系发达且有机酸分泌量较大的先锋植物来修复多金属废渣场地将可能促进废渣中重金属的释放并引起环境生物抗氧化系统和神经系... 相似文献
373.
大蒜培养细胞对水杨酸的应答比对温度和水分胁迫的应答更为强烈,其主要特征是抗氧化酶类超氧化物歧化酶的大量生成,同时还观察到水杨酸对冷胁迫或热休克介导的酶诱导作用的强化.上述结果暗示着自由基的生成是环境胁迫作用于植物细胞的机制之一,水杨酸诱导产生的抗氧化活性高于冷胁迫或热休克.这表明化学胁迫可能以一种与物理胁迫不同的方式诱导超氧化物歧化酶同工酶的生成 相似文献
374.
Steven G. McNulty Johnny L. Boggs 《Environmental pollution (Barking, Essex : 1987)》2010,158(6):2053-2058
Federal agencies of several nations have or are currently developing guidelines for critical forest soil acid loads. These guidelines are used to establish regulations designed to maintain atmospheric acid inputs below levels shown to damage forests and streams. Traditionally, when the critical soil acid load exceeds the amount of acid that the ecosystem can absorb, it is believed to potentially impair forest health. The excess over the critical soil acid load is termed the exceedance, and the larger the exceedance, the greater the risk of ecosystem damage. This definition of critical soil acid load applies to exposure of the soil to a single, long-term pollutant (i.e., acidic deposition). However, ecosystems can be simultaneously under multiple ecosystem stresses and a single critical soil acid load level may not accurately reflect ecosystem health risk when subjected to multiple, episodic environmental stress. For example, the Appalachian Mountains of western North Carolina receive some of the highest rates of acidic deposition in the eastern United States, but these levels are considered to be below the critical acid load (CAL) that would cause forest damage. However, the area experienced a moderate three-year drought from 1999 to 2002, and in 2001 red spruce (Picea rubens Sarg.) trees in the area began to die in large numbers. The initial survey indicated that the affected trees were killed by the southern pine beetle (Dendroctonus frontalis Zimm.). This insect is not normally successful at colonizing these tree species because the trees produce large amounts of oleoresin that exclude the boring beetles. Subsequent investigations revealed that long-term acid deposition may have altered red spruce forest structure and function. There is some evidence that elevated acid deposition (particularly nitrogen) reduced tree water uptake potential, oleoresin production, and caused the trees to become more susceptible to insect colonization during the drought period. While the ecosystem was not in exceedance of the CAL, long-term nitrogen deposition pre-disposed the forest to other ecological stress. In combination, insects, drought, and nitrogen ultimately combined to cause the observed forest mortality. If any one of these factors were not present, the trees would likely not have died. This paper presents a conceptual framework of the ecosystem consequences of these interactions as well as limited plot level data to support this concept. Future assessments of the use of CAL studies need to account for multiple stress impacts to better understand ecosystem response. 相似文献
375.
Major fluorinated chemical manufacturers have developed new short-chain per- and polyfluorinated substances with more favorable environmental, health and safety profiles. This study provides the first evaluation of the elimination half-life of perfluorohexanoic acid (PFHxA) from the blood of humans. PFHxA biomonitoring data were obtained from a recently published study of professional ski wax technicians. These data were analyzed to provide estimates of the apparent half-life of PFHxA from humans, and comparisons were made with kinetic studies of PFHxA elimination from mice, rats and monkeys. The apparent elimination half-life of PFHxA in highly exposed humans ranged between 14 and 49 d with a geomean of 32 d. The half-lives of PFHxA in mice, rats, monkeys and humans were proportional to body weight with no differences observed between genders, indicating similar volumes of distribution and similar elimination mechanisms among mammalian species. Compared to long-chain perfluoroalkyl acid analogs, PFHxA is rapidly cleared from biota. The consistent weight-normalized elimination half-lives for PFHxA in mammalian species indicates that results obtained from animal models are suitable for establishment of PFHxA benchmark dose and reference dose hazard endpoints for use in human risk assessments. 相似文献
376.
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
377.
378.
Persistence and mobility of 2,4-D in unsaturated soil zone under winter wheat crop in sub-tropical region of India 总被引:3,自引:0,他引:3
Manika GuptaN.K. Garg Himanshu JoshiM.P. Sharma 《Agriculture, ecosystems & environment》2012,146(1):60-72
The present study was undertaken to determine the persistence and mobility of 2,4-dichlorophenoxy acetic acid (2,4-D) in unsaturated soil zone under real field conditions for the wheat crop in Roorkee, India. Three experimental plots were chosen in the agricultural field itself to represent the real field conditions in the study area and the potential movement and persistence of herbicide 2,4-D was investigated under three different irrigation treatments. The presence of herbicide along with soil water content was determined in soil at different depths at a temporal scale. The movement of the herbicide was also simulated numerically by solving the coupled soil water content movement and mass transport equations using HYDRUS-1D. The measured soil water content trends and the 2,4-D concentration profiles showed a good agreement with the numerically simulated results. The maximum effect of the herbicide was primarily retained up to 15 cm of the soil profile. The current existing dosage of 0.5 kg ha−1 of pesticide was found to be safe to avoid soil contamination as no residue of 2,4-D was traced at the end of the wheat crop season in any of the plots. Higher concentrations of 2,4-D were also simulated numerically and the simulated results showed that the safe dosage of pesticide application would depend on irrigation treatments. 相似文献
379.
Guanjie Jiang Yonghong Liu Li Huang Qingling Fu Youjun Deng Hongqing Hu 《环境科学学报(英文版)》2012,24(5):919-925
Lead (Pb) chemical fixation is an important environmental aspect for human health. Phosphate rocks (PRs) were utilized as an adsorbent to remove Pb from aqueous solution. Raw PRs and oxalic acid-activated PRs (APRs) were used to investigate the effect of chemical modification on the Pb-binding capacity in the pH range 2.0-5.0. The Pb adsorption rate of all treatments above pH 3.0 reached 90%. The Pb binding on PRs and APRs was pH-independent, except at pH 2.0 in activated treatments. The X-ray diffraction analysis confirmed that the raw PRs formed cerussite after reacting with the Pb solution, whereas the APRs formed pyromorphite. The Fourier Transform Infrared spectroscopy analysis indicated that carbonate (CO32-) in raw PRs and phosphate (PO43-) groups in APRs played an important role in the Pb-binding process. After adsorption, anomalous block-shaped particles were observed by scanning electron microscopy with energy dispersive spectroscopy. The X-ray photoelectron spectroscopy data further indicated that both chemical and physical reactions occurred during the adsorption process according to the binding energy. Because of lower solubility of pyromorphite compared to cerussite, the APRs are more effective in immobilizing Pb than that of PRs. 相似文献
380.