全文获取类型
收费全文 | 803篇 |
免费 | 48篇 |
国内免费 | 224篇 |
专业分类
测绘学 | 17篇 |
大气科学 | 104篇 |
地球物理 | 349篇 |
地质学 | 337篇 |
海洋学 | 131篇 |
天文学 | 35篇 |
综合类 | 39篇 |
自然地理 | 63篇 |
出版年
2023年 | 7篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 13篇 |
2019年 | 9篇 |
2018年 | 14篇 |
2016年 | 12篇 |
2015年 | 19篇 |
2014年 | 36篇 |
2013年 | 24篇 |
2012年 | 47篇 |
2011年 | 52篇 |
2010年 | 16篇 |
2009年 | 24篇 |
2008年 | 47篇 |
2007年 | 39篇 |
2006年 | 41篇 |
2005年 | 50篇 |
2004年 | 50篇 |
2003年 | 40篇 |
2002年 | 36篇 |
2001年 | 31篇 |
2000年 | 35篇 |
1999年 | 23篇 |
1998年 | 17篇 |
1997年 | 19篇 |
1996年 | 10篇 |
1995年 | 16篇 |
1994年 | 23篇 |
1993年 | 28篇 |
1992年 | 24篇 |
1991年 | 28篇 |
1990年 | 30篇 |
1989年 | 26篇 |
1988年 | 30篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 27篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1978年 | 4篇 |
1973年 | 3篇 |
1944年 | 2篇 |
1940年 | 4篇 |
1938年 | 2篇 |
1937年 | 3篇 |
1925年 | 2篇 |
排序方式: 共有1075条查询结果,搜索用时 9 毫秒
101.
正1 Introduction Crystallization is one of important unit operations in the chemical production process,which requires not only the crystal product with high purity and yield,but also the available particle size of the crystal products to ensure product quality.Crystallization process is affected by 相似文献
102.
http://www.sciencedirect.com/science/article/pii/S1674987111001137 总被引:11,自引:1,他引:11
Integration of remote sensing data and the geographical information system(GIS) for the exploration of groundwater resources has become a breakthrough in the field of groundwater research, which assists in assessing,monitoring,and conserving groundwater resources.In the present paper, various groundwater potential zones for the assessment of groundwater availability in Theni district have been delineated using remote sensing and GIS techniques.Survey of India toposheets and IRS-1C satellite imageries are used to prepare various thematic layers viz.lithology,slope,land-use,lineament, drainage,soil,and rainfall were transformed to raster data using feature to raster converter tool in ArcGIS.The raster maps of these factors are allocated a fixed score and weight computed from multi influencing factor(MIF) technique.Moreover,each weighted thematic layer is statistically computed to get the groundwater potential zones.The groundwater potential zones thus obtained were divided into four categories,viz.,very poor,poor,good,and very good zones.The result depicts the groundwater potential zones in the study area and found to be helpful in better planning and management of groundwater resources. 相似文献
103.
含矿相从酸性熔体中分离出来的条件(英文) 总被引:1,自引:1,他引:1
R.N.SOBOLEV V.I.STAROSTIN 《地学前缘》2001,8(3):39-44
热液学说不能完全解释金属从岩浆 (或岩石 )中分离和富集的自然条件。酸性岩中包体研究表明 ,存在特殊的硅酸盐熔体卤水 (silicate saltmelt brine)相 ,它在熔体结晶早期即从中分离出来 ,其中富含盐类 (质量分数可达 70 %)、金属、水、F、Cl、B等。而实验研究显示 ,原始的酸性熔体在冷却过程中分裂为硅酸盐熔体 (silicatemelt)和熔体卤水 (melt brine) ,熔体卤水还可进一步分离出更多的熔体卤水系列 (melt brines) ,它们也富含金属元素。熔体中高度富集的流体是产生这一过程非常有利的条件。 相似文献
104.
105.
106.
107.
该文描述了旋喷注浆在地下24.8-28.3m深处两条3.5m直径质构隧道连接中的应用。两隧道交接处的地层主要为松散的中细粒砂土,其间夹有一些坚固的细粉砂透镜体和坚硬的砂性土。这些坚硬减小了水射流的作用范围。采用与标准旋喷注浆不同的特殊参数与工艺,这一问题得到了解决使得旋喷桩径达到了1.6m。另外,在完成导向孔钻进后,用测斜仪对其进行了垂直精度测量,以确保注浆固结体的均匀性。两质构隧道以成功地连接。 相似文献
108.
109.
110.
Savitri Tripathi Vandana Parth Phani Homeshwari M. Vittal Babu N. Murthy N.N. Sorlie J.E. Govil P.K. 《中国地球化学学报》2006,25(B08):117-118
Permeable Reactive Barrier (PRB) is an emplacement of inert material (s) in the subsurface, designed to intercept a contaminated plume, provides a preferential flow path through the reactive media, and transforms the contaminant into environmentally acceptable forms to attain concentration remediation goals at the discharge of the barrier. The phenomena, which help in remediation within PRB, are adsorption/sorption, precipitation, oxidation/reduction and biodegradation. Various materials like zero-valent iron, zero-valent bi-metals, natural zeolites, organic carbon, fly ash, zeolites, limestone, activated alumina, apatites, etc. have been tried by many researchers to remove organic and inorganic contaminants. In USA, Canada, and many European countries commercial full-scale and pilot scale PRBs are successfully working. The design and installation of full scale PRBs needs laboratory treatability and dynamic flow column experiments? The concept of PRB is being applied to treat contaminated surface water in the Katedan industrial area, Hyderabad, India. National Geophysical Research Institute (NGRI), Hyderabad, India, conducted systematic studies in collaboration with Norwegian Geotechnical Institute (NGI), Norway, to develop PRB technique to decontaminate the surface water pollution due to industrial effluent. A site assessment study in the Katedan Industrial Area, were carried out and water, soil and sediment from the lakes of the area were found to be polluted with high concentrations of heavy metals like As, Pb, Cr, Cd, Ni, etc. Adsorption studies at NGRI with synthetic samples and in-situ industrial effluent using different reactive media for removing contaminants like arsenic, chromium, cadmium, copper, nickel, lead and zinc have been carried out and yielded satisfactory results. The performance of zero-valent iron and limestone is encouraging in removing As, 相似文献