全文获取类型
收费全文 | 5089篇 |
免费 | 357篇 |
国内免费 | 1951篇 |
专业分类
安全科学 | 446篇 |
废物处理 | 251篇 |
环保管理 | 379篇 |
综合类 | 3145篇 |
基础理论 | 852篇 |
污染及防治 | 1578篇 |
评价与监测 | 278篇 |
社会与环境 | 240篇 |
灾害及防治 | 228篇 |
出版年
2024年 | 8篇 |
2023年 | 97篇 |
2022年 | 251篇 |
2021年 | 241篇 |
2020年 | 221篇 |
2019年 | 179篇 |
2018年 | 207篇 |
2017年 | 272篇 |
2016年 | 235篇 |
2015年 | 288篇 |
2014年 | 372篇 |
2013年 | 480篇 |
2012年 | 436篇 |
2011年 | 408篇 |
2010年 | 340篇 |
2009年 | 343篇 |
2008年 | 349篇 |
2007年 | 359篇 |
2006年 | 296篇 |
2005年 | 216篇 |
2004年 | 192篇 |
2003年 | 190篇 |
2002年 | 173篇 |
2001年 | 187篇 |
2000年 | 168篇 |
1999年 | 165篇 |
1998年 | 134篇 |
1997年 | 110篇 |
1996年 | 87篇 |
1995年 | 102篇 |
1994年 | 62篇 |
1993年 | 59篇 |
1992年 | 54篇 |
1991年 | 28篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 15篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有7397条查询结果,搜索用时 203 毫秒
991.
针对我国采用高临界流动水分的磷矿进行湿法生产普钙普遍存在产品水分达不到部颁标准的难题,直接采用制浆废液(利用其主要对环境有害成分之一--MNA作减水剂)进行降低普钙水分的研究和应用.实验结果表明,添加少量的减水剂MNA可显著降低国内朝阳、昆阳、浏阳和国外摩洛哥等单种磷矿以及昆阳-朝阳混矿的矿浆粘度和水分.采用国产昆阳-朝阳混矿进行工业生产试验结果表明,添加0.35%~0.4%干矿粉重量的减水剂MNA,不仅可使球磨添加水量从145 kg降至103 kg,矿浆含水量从30.5%降至27%,成品肥含水量从16.24%降至13.77%,而且可使有效磷从10.67%升至12.24%,转化率由86.57%提高到90.45%,矿浆细度由90.18%提高到93.12%.实验和工业生产试验表明,直接用造纸制浆废液降低普钙水分,既确保和改善了普钙的产品质量,又治理了环境污染,取得了较好的经济、环境和社会效益. 相似文献
992.
993.
The organic precursors affecting the formation of disinfection by-products with chlorine dioxide 总被引:8,自引:0,他引:8
The object of this research was to study the formation of disinfection by-products by using chlorine dioxide (ClO2) as a disinfectant reacting with different properties of organic substance in natural aquatic environment. The adsorbent resin (XAD-4, XAD-7) was used to divide the organic matters in raw water into three groups. The influence of the function groups on structure, reaction tendency, and formation of disinfection by-products generated by the reaction of these organic substances with chlorine dioxide was explored. The experimental results show that the three different organic groups formed using adsorbent resin were hydrophobic substance, hydrophilic acid, and non-acid hydrophilics in proportions of 43%, 41%, and 16%, respectively. Within the raw water in our study, the hydrophilic substance had a higher distribution proportion than that described in general articles and journals, which indicates that this water was contaminated with pollution from human beings. The exploration of the reactivity of the three different organic substances with chlorine dioxide shows that the unit consumption of disinfection agent per unit organic matters (represented by ClO2/DOC) is in the following sequence hydrophobic substance > hydrophilic substance > non-acid hydrophilics. It indicated that larger molecular organic precursors had larger consumption of disinfectant. We also discovered that after the reaction of the three different organic substances with chlorine dioxide, the largest amount of disinfection by-products were generated by the non-acid hydrophilics. 相似文献
994.
Copper contamination in paddy soils irrigated with wastewater 总被引:19,自引:0,他引:19
Copper (Cu) contamination was investigated in paddy soils where Cu-rich wastewater (12 mg Cu/l) was used for irrigation. The results showed that Cu contamination increased the soil Cu content from 17.0 mg Cu/kg in the non-wastewater irrigated soils (NWIS) to 101.2 mg Cu/kg in the wastewater irrigated soils (WIS), and Cu accumulated mostly in the surface layer (0-10 cm) of the paddy soil. The average Cu contents in brown rice, rice hull and rice straw from NWIS were 1.4, 7.3 and 14.5 mg Cu/kg, while those from WIS were 15.5, 133.2, and 101.4 mg Cu/kg, respectively. Correlation analysis revealed that the relationship between the Cu content in the rice straw and the rice hull with the total Cu content of the soil could be described by an exponential function (R2 = 0.921 and 0.831, respectively; P <0.01). Rice plants grown in the WIS showed symptoms of black roots, less effective tiller, etc. Subsequently, the rice yield decreased by 18-25%, compared with that grown in NWIS. 相似文献
995.
Arbuscular mycorrhizae enhance metal lead uptake and growth of host plants under a sand culture experiment 总被引:2,自引:0,他引:2
A sand culture experiment was conducted to investigate whether mycorrhizal colonization and mycorrhizal fungal vesicular numbers were influenced by metal lead, and whether mycorrhizae enhance host plants tolerance to metal lead. Metal lead was applied as Pb(NO3)2 in solution at three levels (0, 300 and 600 mg kg(-1) sand). Five mycorrhizal host plant species, Kummerowia striata (Thunb.) Schindl, Ixeris denticulate L., Lolium perenne L., Trifolium repens L. and Echinochloa crusgalli var. mitis were used to examine Pb-mycorrhizal interactions. The arbuscular mycorrhizal inoculum consisted of mixed spores of mycorrhizal fungal species directly isolated from orchard soil. Compared to the untreated control, both Pb concentrations reduced mycorrhizal colonization by 3.8-70.4%. Numbers of AM fungal vesicles increased by 13.2-51.5% in 300 mg Pb kg(-1) sand but decreased by 9.4-50.9% in 600 mg Pb kg(-1) sand. Mycorrhizae significantly enhanced Pb accumulation both in shoot by 10.2-85.5% and in root by 9.3-118.4%. Mycorrhizae also enhanced shoot biomass and shoot P concentration under both Pb concentrations. Root/shoot ratios of Pb concentration were higher in highly mycorrhizal plant species (K.striata, I. denticulate, and E. crusgalli var. mitis) than that in poorly mycorrhizal ones (L. perenne and T. repens,). Mycorrhizal inoculation increased the root/shoot ratio of Pb concentration of highly mycorrhizal plant species by 7.6-57.2% but did not affect the poorly mycorrhizal ones. In the treatments with 300 Pb mg kg(-1) sand, plant species with higher vesicular numbers tended to show higher root/shoot ratios of the Pb concentration. We suggest that under an elevated Pb condition, mycorrhizae could promote plant growth by increasing P uptake and mitigate Pb toxicity by sequestrating more Pb in roots. 相似文献
996.
997.
北京春节期间大气颗粒物污染及影响 总被引:13,自引:0,他引:13
利用2006年春节期间的大气颗粒物浓度及粒径谱分布资料,结合大气能见度及NO2监测数据,分析了北京市鞭炮燃放禁改限后大气颗粒物污染的变化规律,以及对大气消光作用的影响.结果表明:春节期间特别是除夕夜大量鞭炮的集中燃放导致了大气颗粒物浓度的急剧升高,主要以细粒子为主;颗粒物浓度的升高致使大气能见度明显降低,鞭炮燃放最集中的时段,能见度低于2 km;燃放鞭炮产生的颗粒物是造成大气消光作用的主要因素.估算了北京市鞭炮燃放的颗粒物排放量,2006年除夕0:00~1:00市区排放了大约3.0×104kg PM10,官园监测点PM10小时最高质量浓度超过了800 μg/m3.元宵节夜间燃放鞭炮产生的颗粒物半衰期为2.4 h. 相似文献
998.
999.
1000.