全文获取类型
收费全文 | 4965篇 |
免费 | 432篇 |
国内免费 | 1790篇 |
专业分类
安全科学 | 295篇 |
废物处理 | 301篇 |
环保管理 | 906篇 |
综合类 | 3308篇 |
基础理论 | 794篇 |
污染及防治 | 934篇 |
评价与监测 | 314篇 |
社会与环境 | 279篇 |
灾害及防治 | 56篇 |
出版年
2024年 | 8篇 |
2023年 | 58篇 |
2022年 | 134篇 |
2021年 | 167篇 |
2020年 | 156篇 |
2019年 | 184篇 |
2018年 | 196篇 |
2017年 | 228篇 |
2016年 | 293篇 |
2015年 | 277篇 |
2014年 | 369篇 |
2013年 | 481篇 |
2012年 | 475篇 |
2011年 | 481篇 |
2010年 | 380篇 |
2009年 | 506篇 |
2008年 | 320篇 |
2007年 | 350篇 |
2006年 | 332篇 |
2005年 | 303篇 |
2004年 | 219篇 |
2003年 | 210篇 |
2002年 | 161篇 |
2001年 | 154篇 |
2000年 | 125篇 |
1999年 | 104篇 |
1998年 | 76篇 |
1997年 | 64篇 |
1996年 | 68篇 |
1995年 | 79篇 |
1994年 | 43篇 |
1993年 | 39篇 |
1992年 | 34篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 6篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有7187条查询结果,搜索用时 62 毫秒
31.
32.
33.
国际海事组织目前正在对《MARPOL73/78公约》附则Ⅱ-控制散装液体有毒物质污染规则作重大修改,内容包手胡毒液体物质和化学品,这很可能对主管机关、船公司和化工界造成严重的冲击。 相似文献
34.
Supplementing the nutrient requirement of crops through organic manures plays a key role in sustaining soil fertility, and crop productivity and reducing use of fossil fuels. Field experiments were conducted for 2 years at two different locations (i.e. Lucknow and Pantnagar) in Uttar Pradesh, India. The objectives of the study were to assess the herb and essential oil yields of Japanese mint (Mentha arvensis cv. Hy 77), and its nutrient accumulation under single and combined applications of organic manures and inorganic fertilizers (NPK). Changes in physical and chemical characteristics of the soils (Fluvisols, Mollisols) were also determined. Eight treatments comprising different combinations of NPK through inorganic fertilizers and farm yard manure (FYM) were compared. The distilled waste of mint after extraction of essential oil was recycled to soils in the plots to supplement the nutritional requirement of the succeeding mustard crop (Brassica juncea cv. Pusa Bold). Herb and essential oil yield of mint were significantly higher with combined application of organic and inorganic sources of nutrients as compared to single applications. Accumulation of N and P was at par under full inorganic and combined supply whereas, K accumulation was higher with the former. Soil organic C and pH after harvest of mint did not significantly differ among the treatments, but the level of mineralizable N, Olsen-P and NH4OAc extractable K were higher in soil with integrated supply of nutrients. Significant increase in soil water stable aggregates, organic C, available NPK and microbial biomass, and decrease in soil bulk density were observed with waste recycling over fertilizer application. These benefits were reflected in the seed and stubble yield of mustard which succeeded mint. This study indicates that combined application of inorganic fertilizers with organics helps in increasing the availability of nutrients and crop yield and provides a significant effect to the succeeding crop. Similarly, recycling crop residues reduces the need for fossil fuel based fertilizer, and helps in sustaining and restoring soil fertility in terms of available nutrients and major physical and chemical characteristics of the soil. 相似文献
35.
金属铁还原降解2,4-二硝基甲苯的实验研究 总被引:1,自引:0,他引:1
研究了金属铁对2,4-二硝基甲苯(2,4-DNT)的还原降解情况.实验结果表明,2,4-DNT的还原降解与溶液初始pH值、初始浓度和溶解氧等因素有关.氯离子能消除金属铁的钝化现象.金属铁表面附载的铜对2,4-DNT的还原降解具有催化作用. 相似文献
36.
37.
结合西部干旱半干旱地区的地域特点、水文特征和水资源开发利用状况,分析论述了该地区水资源短缺与水污染加剧这一矛盾所决定的西部地区水资源开发利用的特点及其对地区经济发展的制约,认为水资源的再生利用是解决西部地区水资源危机的一条有效途径。以城市污水为再生水源,根据该区域特点,提出了西部干旱半干旱地区水资源再生利用的研究内容。 相似文献
38.
39.
讨论了铜在淡水藻(Scenedesmus subspicatus86.81SAG)细胞壁和细胞内分布规律,以及乙二胺四乙酸(EDTA)和水体腐殖酸(FA)存在下对铜分布的影响,研究结果表明,EDTA和FA的存在显著降低了细胞表面铜的吸附量,但是不影响细胞内铜的浓度,对测定数据进行分析。可以认为溶液相铜与EDTA或FA形成的铜络合物是生物无效形态,不参与铜在藻细胞壁上特定位点或生物配体的竞争结合反应。 相似文献
40.
Dr Marianne Johansen Marian Knight Edward J. Maher Kim Smith Ian L. Sargent 《黑龙江环境通报》1995,15(10):921-931
Trophoblast deportation is known to occur in normal human pregnancy, but it is not yet clear whether these cells routinely enter the maternal peripheral circulation and are available as a source of fetal DNA for non-invasive prenatal diagnosis of genetic disorders. To resolve this issue requires an efficient method of enriching trophoblast from maternal blood combined with a means to confirm its identity. Five different techniques were tested on ten retroplacental blood samples to determine the most sensitive and operator-efficient method. Lysis of red cells alone gave the best recovery of trophoblast but had to be discounted, together with Ficoll density gradient centrifugation, due to the very low purity and the excessive time required. Fluorescence-activated cell sorting (FACS) of pre-enriched trophoblast resulted in the lowest recovery rate (8 per cent) despite a 3250-fold enrichment and a very high purity. Immunomagnetic beads (Dynabeads) coated with anti-CD 16 antibody proved to be the best method for the subsequent immunocytochemical characterization of deported trophoblast. However, IO beads coated with anti-CD45 antibody may be more useful for isolating trophoblast for prenatal diagnosis due to the high purity, enrichment (32-fold), and recovery rate (78 per cent) obtained with this method. 相似文献