全文获取类型
收费全文 | 3696篇 |
免费 | 328篇 |
国内免费 | 1124篇 |
专业分类
安全科学 | 371篇 |
废物处理 | 158篇 |
环保管理 | 264篇 |
综合类 | 2305篇 |
基础理论 | 582篇 |
环境理论 | 2篇 |
污染及防治 | 791篇 |
评价与监测 | 219篇 |
社会与环境 | 214篇 |
灾害及防治 | 242篇 |
出版年
2024年 | 12篇 |
2023年 | 70篇 |
2022年 | 216篇 |
2021年 | 168篇 |
2020年 | 166篇 |
2019年 | 130篇 |
2018年 | 150篇 |
2017年 | 139篇 |
2016年 | 175篇 |
2015年 | 200篇 |
2014年 | 252篇 |
2013年 | 327篇 |
2012年 | 357篇 |
2011年 | 349篇 |
2010年 | 285篇 |
2009年 | 255篇 |
2008年 | 255篇 |
2007年 | 258篇 |
2006年 | 259篇 |
2005年 | 178篇 |
2004年 | 114篇 |
2003年 | 101篇 |
2002年 | 114篇 |
2001年 | 92篇 |
2000年 | 111篇 |
1999年 | 74篇 |
1998年 | 55篇 |
1997年 | 65篇 |
1996年 | 57篇 |
1995年 | 44篇 |
1994年 | 33篇 |
1993年 | 16篇 |
1992年 | 24篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有5148条查询结果,搜索用时 31 毫秒
361.
将B-P网络原理与逐步聚类分析思想相结合,用于环境测点聚类优选。该方法用于水清河几个监测断面的优选结果是符合客观实际的。 相似文献
362.
实验性糖尿病新西兰兔主要器官组织的病理学观察 总被引:2,自引:0,他引:2
将雄性新西兰兔随机分为:基础饲料组(即对照组:n=15)和高糖高脂饲料组(即实验组:n=15,喂食10%猪油,37%白蔗糖混合53%的基础饲料).共观察12周.于12周实验结束时,全部处死动物,取动物心脏、肝脏、胰腺、肾脏,用1O%福尔马林液固定,常规石蜡包埋切片,H、E染色,光学显微镜下观察并照相.结果表明:动物心肌细胞肥大,并出现灶性坏死,淋巴细胞浸润,心肌细胞间成纤维细胞增生和毛细血管增生,胶原纤维增加;肝细胞有明显脂肪变性,细胞肿胀;肾脏表现有肾小球球囊增大,细胞增多,毛细血管壁增厚,肾小管上皮细胞胞体增大;胰腺组织表现为胰岛分布稀疏,数量减少,胰岛萎缩,胰岛细胞数量减少,成纤维细胞增生. 相似文献
363.
贵州省煤中挥发性和半挥发性微量元素分布规律的初步研究 总被引:25,自引:0,他引:25
研究了贵州省四大煤田不同层位、不同煤种中Hg,As,Se,Pb,Cd,Tl,Zn,Sb等挥发性和半挥发性微量元素的分布规律。贵州省原煤中Hg,As,Se,Pb,Cd,Sb等元素的含量高于地壳克拉克值;Tl,Zn等的含量低于地壳克拉克值;另外,除了Pb,Zn外,贵州省原煤中Hg,As,Se,Cd的含量远远高于东北和内蒙古东部地区。微量元素聚类分析结果表明,Hg,As,Sb可能主要分布于煤的黄铁矿中;Zn和Se可能主要赋存于闪锌矿中;Cd可能部分存在于硫化物中,部分存在于硅酸盐矿物相中;Pb可能主要存在于硅酸盐矿物相中;而Tl在煤中的赋存形式较复杂。 相似文献
364.
Effects of crude oil residuals on soil chemical properties in oil sites, Momoge Wetland, China 总被引:1,自引:0,他引:1
Crude oil exploration and production has been the largest anthropogenic factor contributing to the degradation of Momoge Wetland, China. To study the effects of crude oil on wetland soils, we examined the total petroleum hydrocarbon (TPH), total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP), as well as pH and electricity conductivity (EC) from oil sites and uncontaminated areas in the Momoge Wetland. All contaminated areas had significantly higher (p < 0.05) contents of TPH and TOC, but significantly lower (p < 0.05) TN contents than those of the uncontaminated areas. Contaminated sites also exhibited significantly higher (p < 0.05) pH values, C/N and C/P ratios. For TP contents and EC, no significant changes were detected. The level of soil contamination and impact of oil residuals on soil quality greatly depended on the length of time the oil well was in production. Oil residuals had caused some major changes in the soils’ chemical properties in the Momoge Wetland. 相似文献
365.
Lan Q Cui K Zeng F Zhu F Liu H Chen H Ma Y Wen J Luan T Sun G Zeng Z 《Environmental monitoring and assessment》2012,184(8):4921-4929
Phthalate esters (PAEs) were examined in indoor and outdoor dust samples from the subtropical city of Guangzhou, China. The ∑(16)PAEs concentrations ranged from 121 to 3,223 μg g(-1) dust, with the median concentration of 840 μg g(-1) dust. Significantly higher concentrations of PAEs in dust samples were found in offices where electrical and electronic devices, carpet pads, and office furniture were widely used. Of the 16 PAEs, diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and di(2-ethylhexyl) phthalate (DEHP) dominated the PAEs in indoor and outdoor dust samples, and accounted for >96.8% and >93.1% of the ∑(16)PAEs concentrations, respectively. The median daily inhalation exposure of ∑(16)PAEs were 3.53 and 0.247 μg kg(-1) body weight day(-1), and at the 95(th) percentile were 7.62 and 0.530 μg kg(-1) body weight day(-1), up on the measured concentrations and estimated dust ingestion rates, respectively, for toddles and adults. The ubiquitous distribution of PAEs as noted in this study suggests the need for detailed assessment of PAEs concentrations using more sites and to further investigate the factors influencing PAEs exposure in China. 相似文献
366.
Li YX Han W Yang M Feng CH Lu XF Zhang FS 《Environmental monitoring and assessment》2012,184(8):5035-5041
Concentrated animal feeding operations have been recognized as one of the most important contributors of natural estrogens which show significant endocrine-disrupting properties in aquatic environments. In this study, the concentrations of 17α-estradiol (17α-E2), 17β-estradiol (17β-E2), estrone (E1), and estriol (E3) in several matrices, including soils (surface and deep), sediments (surface and deep), and groundwaters, around a typical dairy farm were surveyed using gas chromatography/mass spectrometry. Of the two farmlands, surface and subsurface sediments in waste lagoon and along effluent drainage drench, the concentrations of 17α-E2, 17β-E2, and E1 ranged from below detection limit to the highest level of 6.60 μg/kg, except that E3 was not detectable. Three estrogens of 17α-E2, 17β-E2, and E1 with the concentrations of 3.18-31.61 ng/L were observed in two groundwater samples. The results clearly demonstrated the vertical migration and horizontal transport of estrogens in the investigated area. Within 750-m distance, it was observed the attenuation of 17α-E2, 17β-E2, and E1 along the effluent route and the horizontal migration of estrogens was less than 1,350 m in this survey. 相似文献
367.
The accelerated industrialization and urbanization in the last three decades around the Pearl River Delta within Guangdong Province in China have led to serious concerns about the impacts on the aquatic environment. In the present study, the genotoxicity of the sediments collected from the Pearl River was evaluated by micronucleus (MN) assay with Vicia faba root tip cells, and the 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs, including Cr, Cu, As, Se, Cd, Hg, and Pb) in the sediments were determined respectively by GC-MS, inductively coupled plasma mass spectrometry, and inductively coupled plasma atomic emission spectrometry. The results showed that there were significant increases of MN frequencies observed in the sediment-exposed groups, compared with the negative group (P?0.05, P?0.01), indicating that the sediments clearly had genotoxicity to the V. faba root cells. The total concentrations of the priority PAHs (250-13,656 ng g(-1), dry weight) and HMs (As, 22,770-36,639 μg kg(-1); Cr, 39,333-133,343 μg kg(-1); Cu, 36,145-159,270 μg kg(-1); Pb, 51,210-166,642 μg kg(-1); Cd, 475.4-1,818.9 μg kg(-1); Hg, 59.9-460.8 μg kg(-1); and Se, 331.7-1,250.4 μg kg(-1), dry weight) were close to those obtained from other urbanized and industrialized areas, which have been considered moderately polluted. There was a clear positive correlation between MN potency and the molar concentrations of Hg and Pb in the sediments (Hg, r?=?0.94; Pb, r?=?0.91), suggesting that Hg and Pb were the most important factors that posed the sediments higher genotoxicity to V. faba root cells. Our results suggested that both biological and chemical approaches are necessary to be included in a battery of tests to assess the eco-environmental risks of sediments. 相似文献
368.
369.
370.
北京地区冬季典型PM2.5重污染案例分析 总被引:9,自引:6,他引:3
对2013年1月10—14日发生的持续性PM2.5重污染过程从污染过程演变、气象条件影响、与气态污染物关系、区域污染背景、PM2.5浓度空间分布演变及其与地面风场的关系、PM2.5组分特征等多个方面进行全面的分析,较为完整地还原了该次重污染案例的形成原因以及主要影响因素。主要结论包括:该次重污染过程是稳定气象条件下导致的局地污染物积累,再叠加华北区域性污染的影响共同造成,其中10、12日北京地区PM2.5浓度的快速增长反映了周边污染传输的显著影响;逆温不但造成污染物难以扩散,且不同的逆温类型对PM2.5浓度水平有显著影响,同时还发现逆温的破坏导致近地面高浓度污染物向上扩散,造成百花山出现峰值高污染浓度现象;NO2与PM2.5浓度水平的高相关性反映交通污染二次转化对PM2.5浓度水平的影响,在较高湿度条件下,SO2浓度水平对湿度敏感且表现为负相关性;该次污染过程中OM、SO2-4、NO-3、NH+4等组分在PM2.5质量浓度中的占比超过70%,说明燃煤、机动车等仍是北京地区最主要的污染来源,同时SO2-4占比最高也说明区域污染传输对该次重污染的显著贡献。 相似文献