全文获取类型
收费全文 | 2491篇 |
免费 | 190篇 |
国内免费 | 703篇 |
专业分类
安全科学 | 194篇 |
废物处理 | 118篇 |
环保管理 | 193篇 |
综合类 | 1419篇 |
基础理论 | 417篇 |
污染及防治 | 590篇 |
评价与监测 | 150篇 |
社会与环境 | 155篇 |
灾害及防治 | 148篇 |
出版年
2024年 | 8篇 |
2023年 | 37篇 |
2022年 | 130篇 |
2021年 | 119篇 |
2020年 | 102篇 |
2019年 | 99篇 |
2018年 | 107篇 |
2017年 | 106篇 |
2016年 | 107篇 |
2015年 | 144篇 |
2014年 | 190篇 |
2013年 | 223篇 |
2012年 | 232篇 |
2011年 | 209篇 |
2010年 | 204篇 |
2009年 | 156篇 |
2008年 | 171篇 |
2007年 | 148篇 |
2006年 | 156篇 |
2005年 | 115篇 |
2004年 | 81篇 |
2003年 | 83篇 |
2002年 | 83篇 |
2001年 | 75篇 |
2000年 | 58篇 |
1999年 | 40篇 |
1998年 | 36篇 |
1997年 | 31篇 |
1996年 | 25篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 20篇 |
1992年 | 14篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有3384条查询结果,搜索用时 15 毫秒
371.
372.
太行山是我国山地植被破坏历史最长、生态环境严重恶化的山地生态系统,“七五”期间国家将绿化太行山列入重点攻关项目。从1986年开始,作者根据生态工程原理提出:环境辨识工程、种群引进选择工程、种群匹配工程、水土富集工程、时间节律工程和食物链工程为主的立体林业工程新思想,并在湘山小流域建起实施模式。经四年的工作,已取得较大进展。 相似文献
373.
Guohua Su Yelin Huang Fengxiao Tan Xiaowei Ni Tian Tang Suhua Shi 《Marine Biology》2007,150(3):321-328
Mangrove forests, with their ecological significance and economic benefits, are vital inter-tidal wetland ecosystems. Lumnitzera littorea (Combreataceae) is a non-viviparous mangrove distributed in tropical Asia and North Australia. Due to natural and human impacts, populations of this species have been isolated, fragmented, and highly disturbed. In China, L. littorea is an endangered species, restricted to small regions of Hainan Island. The genetic composition of five populations of this species from the Indo-West Pacific (South China, Malay Peninsula, Sri Lanka, North Australia) was assessed using inter simple sequence repeat (ISSR) makers. At the species level, expected mean heterozygosity (He) was 0.240 with 75.6% of loci polymorphic (P). However, genetic variation was much lower at the population level (P = 37.1%, He = 0.118). A high coefficient of gene differentiation (Gst = 0.515) and low level of gene flow (Nm = 0.470) indicated significant genetic differentiation among populations. AMOVA also indicated that more than half the total variation (58.4%) was partitioned among populations. The high degree of differentiation observed among populations emphasizes the need for appropriate conservation measures that incorporate additional populations into protected areas, and achieve the restoration of separate, degraded populations. 相似文献
374.
蒋筠 《城市环境与城市生态》2002,15(2):62-62
分析了9112-B型有毒药物安全操作台的污染物去除效率,得出了该操作平台避免了有毒药物对操作者的侵害,减少了有毒药物对环境污染的结论。 相似文献
375.
Prorocentrum lima (Ehrenberg) Dodge, one of the cosmopolitan dinoflagellates, is basically benthic and is found on the surface of macroalgae and detritus. The identification of this species requires detailed morphological observation because of its close similarity to other benthic Prorocentrum species. The purpose of this study is to detect the morphological variability of P. lima using culture clones collected from several areas to find an adequate way of subdividing the species. In this study, 33 clones of P. lima were collected from Saipan, Tahiti, Indonesia, Japan and Bermuda, and their thecal valves and periflagellar area were observed by means of light microscopy with differential interference contrast optics and scanning electron microscopy. In general cells have two centrally located pyrenoids and a posterior nucleus. The surface of both valves has many valve pores except the center. Evenly spaced marginal pores are located along the edge of the valves. P. lima samples studied herein were subdivided into four major types (ellipsoidal, general, short, and elongate ovoid) according to their shapes, length-to-width ratio and number of valve pores. The length-to-width ratios of ellipsoidal, general, short, and elongate ovoid types were 1.32, 1.33-1.43, 1.20-1.27, and 1.53-1.60 microm respectively. Also there were slight differences in the number of valve pores. The number of valve pores examined in this study ranges from 40 to 97: ellipsoidal, general, and short ovoid types range from 40 to 91, while an elongate ovoid type ranges from 80 to 97. The combination of valve shape, number of valve pores and length-to-width ratio provides useful information on the morphological variation of P. lima. 相似文献
376.
京杭运河徐州段底栖动物与水质的关系 总被引:7,自引:0,他引:7
本研究利用生物监测方法,探明了京杭运河徐州段大型底栖无脊椎动物的生物种群及其分布。运用污染生物指数(Goodnight)和生物多样性指数(Shannon)统计表达,对京杭运河徐州段进行生物综合评价,同时,指出了该水体污染,将给徐州的两个地面饮用水厂及国家南水北调工程带来威胁和危险。通过生物指标与理化指标对比,综合分析研究,冲破了理化指标的限制,说明生物指标对水体污染的评价更全面、可靠而直观。 相似文献
377.
沈阳市区大气颗粒物元素组分及其分布 总被引:3,自引:1,他引:3
本研究采用美国安德逊五段冲击式采样器进行大气颗粒物采样,用中子活化法进行分析,获得43种元素质量浓度,并求得各种元素的质量中值直径和几何标准差。 相似文献
378.
379.
表面活性剂AE对黄鳝保护酶SOD、CAT和GSH-PX活性的影响 总被引:5,自引:0,他引:5
以肝脏组织保护酶λ(SOD)、λ(CAT)和λ(GSH PX)为指标 ,研究了表面活性剂AE(脂肪醇聚氧乙烯醚 )污染对黄鳝 (Monopterusalbus)的损伤作用 .结果显示 :ρ(AE) 1.5mg/L处理液对黄鳝的损伤较小 ;随着 ρ(AE)升高 ,损伤程度加剧 .ρ(AE) >4 .5mg/L的处理液对黄鳝损伤较大 ,保护酶λ(SOD)、λ(CAT)在处理 96h后被抑制 ,λ(GSH PX)升高 .发现环境中AE的残留量对黄鳝种群有影响 .也证实了λ(SOD)、λ(CAT)和λ(GSH PX)变化可以反映黄鳝的伤害程度 .表 3参 14 相似文献
380.