全文获取类型
收费全文 | 8764篇 |
免费 | 538篇 |
国内免费 | 1900篇 |
专业分类
安全科学 | 725篇 |
废物处理 | 394篇 |
环保管理 | 757篇 |
综合类 | 4257篇 |
基础理论 | 1970篇 |
环境理论 | 2篇 |
污染及防治 | 1737篇 |
评价与监测 | 513篇 |
社会与环境 | 493篇 |
灾害及防治 | 354篇 |
出版年
2024年 | 23篇 |
2023年 | 96篇 |
2022年 | 303篇 |
2021年 | 281篇 |
2020年 | 264篇 |
2019年 | 201篇 |
2018年 | 342篇 |
2017年 | 359篇 |
2016年 | 430篇 |
2015年 | 360篇 |
2014年 | 406篇 |
2013年 | 532篇 |
2012年 | 970篇 |
2011年 | 762篇 |
2010年 | 472篇 |
2009年 | 465篇 |
2008年 | 487篇 |
2007年 | 506篇 |
2006年 | 522篇 |
2005年 | 722篇 |
2004年 | 755篇 |
2003年 | 585篇 |
2002年 | 238篇 |
2001年 | 206篇 |
2000年 | 192篇 |
1999年 | 159篇 |
1998年 | 88篇 |
1997年 | 100篇 |
1996年 | 91篇 |
1995年 | 80篇 |
1994年 | 49篇 |
1993年 | 27篇 |
1992年 | 34篇 |
1991年 | 26篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1981年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
Although amphibians are highly vocal, they generally emit only a limited number of acoustic communication signals. We report here the extraordinarily rich vocal repertoire of Amolops tormotus, a ranid species in China. These frogs produce countless vocalizations, some of which share features of birdsong or primate calls, e.g., ultrasonic frequency components, multiple upward and downward FM sweeps, and sudden onset and offset of selective harmonic components within a call note. Frame-by-frame video analysis of the frog's calling behavior suggests the presence of two pairs of vocal sacs that may contribute to the remarkable call-note complexity in this species. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00114-002-0335-x. 相似文献
142.
143.
144.
脱硫石膏综合利用现状及其抹面材料的研制 总被引:2,自引:0,他引:2
概述了目前有关脱硫石膏性能及其利用的研究现状,研究开发了建筑用脱硫石膏抹面材料,此种材料经性能检测,其抗压强度、抗折强度分别达到4.5MPa、17.5MPa,且粘结性能优良,为脱硫石膏的再生利用提供了另外一条有效的途径。 相似文献
145.
146.
147.
148.
膜生物反应器运行中的膜污染问题 总被引:9,自引:0,他引:9
这了各国研究者针对膜生物反应器中的膜污染问题所作的工作,认为膜本身的性质以及废水组成和工艺条件都是造成膜污染的主要原因,利用反冲洗和清洗手段,可以有效地改善膜的性能,以提高膜的寿命,膜生物反应器技术的改进是避免膜污染的新思路。 相似文献
149.
目前,我国正大力推行排放污染物总量控制计划。本文探讨了如何更经济更合理地实施控制计划,如何以最小的代价实际控制目标。 相似文献
150.
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