全文获取类型
收费全文 | 6206篇 |
免费 | 230篇 |
国内免费 | 1211篇 |
专业分类
安全科学 | 298篇 |
废物处理 | 348篇 |
环保管理 | 539篇 |
综合类 | 2355篇 |
基础理论 | 1661篇 |
环境理论 | 2篇 |
污染及防治 | 1612篇 |
评价与监测 | 344篇 |
社会与环境 | 343篇 |
灾害及防治 | 145篇 |
出版年
2024年 | 9篇 |
2023年 | 76篇 |
2022年 | 188篇 |
2021年 | 201篇 |
2020年 | 153篇 |
2019年 | 98篇 |
2018年 | 265篇 |
2017年 | 279篇 |
2016年 | 354篇 |
2015年 | 245篇 |
2014年 | 306篇 |
2013年 | 356篇 |
2012年 | 704篇 |
2011年 | 510篇 |
2010年 | 231篇 |
2009年 | 239篇 |
2008年 | 287篇 |
2007年 | 221篇 |
2006年 | 251篇 |
2005年 | 538篇 |
2004年 | 615篇 |
2003年 | 515篇 |
2002年 | 123篇 |
2001年 | 124篇 |
2000年 | 120篇 |
1999年 | 116篇 |
1998年 | 91篇 |
1997年 | 85篇 |
1996年 | 75篇 |
1995年 | 67篇 |
1994年 | 48篇 |
1993年 | 34篇 |
1992年 | 46篇 |
1991年 | 20篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1984年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 3篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有7647条查询结果,搜索用时 218 毫秒
91.
In Acromyrmex octospinosus leaf-cutting ants the metapleural glands produce an array of antibiotic compounds that serve as a general defence against unwanted microbes on the cuticle. Leaf-cutting ants also grow mutualistic Pseudonocardiaceae bacteria on their cuticle that produce antibiotics controlling a microfungal parasite of their fungus gardens. Interaction between this bacterium and gland secretion therefore seems unavoidable. We document the typical development of bacterial growth on the cuticle of young major workers, show that growth starts a few days after eclosion, and that the maximal cover is reached after 2–3 weeks and gradually declines when workers mature. Experimental closure of the metapleural glands had no effect on the initial exponential growth phase of the bacterium, but significantly reduced the cover during the decline phase. The age-dependent abundance of the bacterium and its partial dependence on metapleural gland secretion support the hypothesis that the abundance of this mutualist is actively regulated. 相似文献
92.
93.
通过对解放碑商业中心区1991-2000年环境噪声监测结果的分析评价,比较了十年均噪声的时间分布污染和1998-2000年的季平均噪声的时间分布污染状况,得出该商业地区噪声污染在昼间15:00-17:00最高,夜间在4:00左右最低;四季中,秋季的昼间噪声最高,冬季的夜间的噪声最低,其昼间噪声的波动幅度也较小,与人群的社会行为活动密切相关。 相似文献
94.
化工生产一般采用温控分离、氧化还原、催化裂解、压力聚合等工艺方法,而化工产品特别是中间产品一般都具有易燃、易爆、有毒、有害和腐蚀等特点.在化工生产的过程中可能发生的各类灾害事故已经成为各级政府和应急救援单位研究的重要课题.下面结合工作实践谈谈化工装置灾害事故的处置思路. 相似文献
95.
96.
本文概述了设计集油污水接纳,分离处理,分析监控于一体的军港舰船油污水处理系统。该系统能全方位,快速安全地解决舰船油污水的接纳难题。该系统分离技术可靠,工艺设计合理,实用性好,适用性强,运用费用低,处理效果佳,达到了防止军港污染,保护海洋环境这一目的,收到了较好的环境,社会和经济效益。 相似文献
97.
98.
用植物清除土壤中的重金属 总被引:11,自引:0,他引:11
介绍了生物修复技术去除土壤中的重金属及对植物的要求.植物能去除土壤中的有毒金属,将金属富集在生物体内,或将金属变成挥发性气体. 相似文献
99.
脉冲等离子法烟气脱硫的放大实验 总被引:2,自引:0,他引:2
锅炉烟气进行脉冲等离子法脱硫的扩大实验,得到与模拟烟气实验相近的结果。研究表明,脉冲等离子法对锅炉烟气中的SO2去除率可达95%以上,烟气在反应器内的停留时间(ts)、脉冲电源的放电功率(P)和添加NH3等条件,对脱硫效率9η)有较大影响。ts、P越大、η越高。处理烟气量(Q)、能耗(P)与η存在函数关系:η=118.0(P/Q)^0.1111。烟气中加入适量NH3,对脱硫效率有显著提高,以NH3 相似文献
100.
Stratigraphy, lithology and depositional structures of Liassic red limestone-breccias of the Adnet Formation, including the 'Adnet Scheck', were studied at several outcrops of the Northern Calcareous Alps (NCA) south-east of Salzburg. A four-fold lithostratigraphic division is proposed for the Adnet Formation of the Osterhorn Mountains: the hemipelagic Schmiedwirt (Sinemurian) and Kehlbach (Carixian) members are separated from the pelagic Saubach Member (Toarcian) by a layer of amalgamated breccias (Scheck Member, probably Domerian to early Toarcian). Several other breccia beds occur locally from the base of the Kehlbach Member up to the lower Saubach Member. Although the sediments overlying the Scheck Member breccias are of coeval age, the ages of the underlying strata are very different. This can be explained by submarine Liassic erosion during a period of resedimentation from the middle Carixian until the early Toarcian. At least 10–15?m of partly lithified sediments were eroded by gravity flows. The entire Kehlbach Member and up to two-thirds of the Schmiedwirt Member were removed at Adnet. The breccias originated from submarine debris flows. Repeated flows over a long period and the depositional setting exclude a triggering by sea-level fluctuations. Most probably they arose from tectonically triggered slumps and slides of superficial sediments. The 'Scheck' was initiated on the steep upper slope of the drowned Triassic Adnet reef and flowed to the north-east.The Pliensbachian to early Toarcian period of tectonic activity indicated by the breccias was the most important during the Liassic in the Osterhorn Mountains and other parts of the NCA. From the large-scale regional distribution of the breccias and in accord with published data, a roughly north-east trending strike-slip fault zone is proposed, crossing the NCA south of the Osterhorn block, with a peaking activity during the Pliensbachian to early Toarcian as the cause of the tectonic movements. 相似文献