全文获取类型
收费全文 | 60911篇 |
免费 | 653篇 |
国内免费 | 758篇 |
专业分类
安全科学 | 2004篇 |
废物处理 | 2764篇 |
环保管理 | 7923篇 |
综合类 | 9905篇 |
基础理论 | 16309篇 |
环境理论 | 28篇 |
污染及防治 | 15160篇 |
评价与监测 | 4153篇 |
社会与环境 | 3678篇 |
灾害及防治 | 398篇 |
出版年
2022年 | 553篇 |
2021年 | 587篇 |
2020年 | 417篇 |
2019年 | 499篇 |
2018年 | 967篇 |
2017年 | 1005篇 |
2016年 | 1494篇 |
2015年 | 1099篇 |
2014年 | 1610篇 |
2013年 | 4775篇 |
2012年 | 2290篇 |
2011年 | 2837篇 |
2010年 | 2199篇 |
2009年 | 2238篇 |
2008年 | 2671篇 |
2007年 | 2718篇 |
2006年 | 2413篇 |
2005年 | 2303篇 |
2004年 | 2296篇 |
2003年 | 2274篇 |
2002年 | 1822篇 |
2001年 | 2258篇 |
2000年 | 1616篇 |
1999年 | 989篇 |
1998年 | 695篇 |
1997年 | 746篇 |
1996年 | 746篇 |
1995年 | 884篇 |
1994年 | 825篇 |
1993年 | 687篇 |
1992年 | 733篇 |
1991年 | 720篇 |
1990年 | 724篇 |
1989年 | 674篇 |
1988年 | 587篇 |
1987年 | 536篇 |
1986年 | 504篇 |
1985年 | 529篇 |
1984年 | 553篇 |
1983年 | 531篇 |
1982年 | 533篇 |
1981年 | 463篇 |
1980年 | 390篇 |
1979年 | 420篇 |
1978年 | 369篇 |
1977年 | 308篇 |
1975年 | 305篇 |
1974年 | 279篇 |
1973年 | 299篇 |
1972年 | 299篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
981.
Robert M. Wolcott Marco Antonio González 《Mitigation and Adaptation Strategies for Global Change》1997,2(2-3):vii-viii
Mitigation and Adaptation Strategies for Global Change - 相似文献
982.
983.
984.
985.
986.
987.
In several branches of science and technology a gaseous phase is dispersed into a liquid in the form of bubbles, a gaseous
component then dissolves into the liquid and subsequently undergoes chemical reaction. The overall process performance can
be improved substantially when the area of gas–liquid contact is increased. By subjecting the liquid phase to low frequency
vibrations, the bubbles are shown to suffer significant breakage, induced by resonance. When the vibration is properly tuned,
the interfacial area is found to increase by a factor of 1.8–2.4, depending on the properties of the liquid. Resonance-induced
bubble breakage phenomena have a great potential for improving the rates of chemical processes involving fast reactions, with
minimal energy input.
Received: 7 July 2000 / Accepted in revised form: 28 August 2000 相似文献
988.
The groundwater regime in Upper Palar basin, Tamilnadu has been highly contaminated in several locations due to discharge of effluents from a large number of tanneries. At some places total dissolved solids (TDS) concentration in groundwater was found as high as 8000 mg/l. Transmissivity and storativity of the regional aquifer were estimated at a few locations. The porosity and dispersivity values were not determined in the field. These parameters were assumed based on data available for similar geological formations elsewhere. The aquifer conceptualization thus arrived at formed the basis of a numerical groundwater flow model which was constructed using the finite difference method. The flow model was calibrated for steady state and then for transient condition for the period of 1984-92. The computed heads and calibrated parameters of the flow model were used to compute groundwater velocities. The migration of contaminants for a 20 year period was computed using the hydraulic heads and effective porosity value in a pathline model using FLOWPATH software. Mass transport model was constructed using Method of Characteristics (MOC) computer code in a separate model. The seepage rate of effluent is assumed at a rate of 30% of that discharged on the surface. The mass concentration of solute in the effluent reaching the water table was assumed as 40%, the same as in the surface effluent. The mass transport model was calibrated for a 20 year period. Prediction of contaminant migration from different clusters in the basin was analyzed. The prediction results indicated elevated TDS concentration of more than 4000 mg/l from most clusters. Also the area of the contaminated zone is likely to double in 20 years from contaminated zone of 1992. 相似文献
989.
This paper investigates the current treatment of environmental issues by two companies within the large made-to-order sector. Fifty questionnaires were issued to the design team of each company to assess current practice in the integration of environmental issues with design activities, awareness of environmental issues, awareness of existing environmental design tools and the preferred format for a potential clean design tool. 相似文献
990.
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