全文获取类型
收费全文 | 5585篇 |
免费 | 280篇 |
国内免费 | 23篇 |
专业分类
测绘学 | 189篇 |
大气科学 | 390篇 |
地球物理 | 2160篇 |
地质学 | 1899篇 |
海洋学 | 210篇 |
天文学 | 821篇 |
综合类 | 31篇 |
自然地理 | 188篇 |
出版年
2022年 | 44篇 |
2021年 | 106篇 |
2020年 | 105篇 |
2019年 | 77篇 |
2018年 | 253篇 |
2017年 | 238篇 |
2016年 | 354篇 |
2015年 | 258篇 |
2014年 | 274篇 |
2013年 | 357篇 |
2012年 | 309篇 |
2011年 | 251篇 |
2010年 | 242篇 |
2009年 | 252篇 |
2008年 | 194篇 |
2007年 | 141篇 |
2006年 | 142篇 |
2005年 | 121篇 |
2004年 | 111篇 |
2003年 | 120篇 |
2002年 | 89篇 |
2001年 | 92篇 |
2000年 | 93篇 |
1999年 | 54篇 |
1998年 | 85篇 |
1997年 | 69篇 |
1996年 | 43篇 |
1995年 | 71篇 |
1994年 | 83篇 |
1993年 | 49篇 |
1992年 | 46篇 |
1991年 | 43篇 |
1990年 | 58篇 |
1989年 | 43篇 |
1988年 | 41篇 |
1987年 | 36篇 |
1986年 | 43篇 |
1985年 | 46篇 |
1984年 | 37篇 |
1983年 | 46篇 |
1982年 | 50篇 |
1981年 | 42篇 |
1980年 | 43篇 |
1979年 | 40篇 |
1978年 | 50篇 |
1977年 | 41篇 |
1975年 | 41篇 |
1974年 | 31篇 |
1973年 | 43篇 |
1971年 | 39篇 |
排序方式: 共有5888条查询结果,搜索用时 0 毫秒
141.
C. M. Morales-Bautista R. H. Adams J. R. Hernández-Barajas C. E. Lobato-García J. G. Torres-Torres 《International Journal of Environmental Science and Technology》2016,13(11):2689-2696
In many petroleum-producing regions, there are not adequate controls to prevent pipeline breaks and spills, and thus soil is frequently contaminated with petroleum hydrocarbons. Different petroleum oil compounds may produce negative impacts on soil fertility. In this study, four fresh crudes, a weathered petroleum, and oils from bioremediated and burned sites were investigated (specific gravities 0.83–1.27). Fourier transform infrared spectroscopy revealed three predominant polar functional groups to be more plentiful in the heavier crudes. The relative abundance of these groups was used to calculate an index that was directly correlated with specific gravity (R 2 = 0.9960) and the percent of asphaltene plus (polars + resins) fractions in the oil (R 2 = 0.9643). This index correlated exponentially to the water repellency caused by petroleum in an alluvial soil (R 2 = 0.9928). Furthermore, extra-heavy oil at a concentration of 10,000 ppm, the maximum allowable oil concentration in the soil that is within regulatory norms in many US states and other countries, and with a specific gravity >1.002, showed severe water repellency. This study presents an alternative for determining soil remediation criteria based on the API gravity of the oil rather than the C-range of the hydrocarbon mixtures, simplifying analytical methods and systematically studying the interaction between the kinds of petroleum mixtures and potential impacts to soil fertility. 相似文献
142.
M. Vochozka A. Maroušková J. Váchal J. Straková 《International Journal of Environmental Science and Technology》2016,13(6):1607-1614
A positive energy balance caused by accelerated production of CH4 and additional financial benefits associated with shorter retention times, reduction in volumes, easier dewatering, enhanced hygiene, etc., are the reasons why most modern wastewater treatment plants are newly equipped with hydrothermal pretreatment units. This study examined how the changes in composition of the pretreated sewage sludge fermentation residues manifested themselves in subsequent processing by pyrolysis, both in terms of technology and financial impacts. It has been found that concentrations of heavy metals and other hazardous inhibitors might increase; however, the overall biotoxicity is lower due to their immobilization in the charred mass. Moreover, charring of the fermentation residues results in significant financial as well as technological benefits. 相似文献
143.
144.
145.
146.
147.
148.
149.
Terrinha Pedro Pueyo Emilio L. Aranguren Aitor Kullberg José Carlos Kullberg Maria Carla Casas-Sainz Antonio Azevedo Maria do Rosário 《International Journal of Earth Sciences》2018,107(5):1807-1833
International Journal of Earth Sciences - The geometry and emplacement of the ~ 96 km2, Late Cretaceous Sintra Igneous complex (SIC, ca. 80 Ma) into the West Iberian passive... 相似文献
150.
López-Moro F. J. López-Plaza M. Gutiérrez-Alonso G. Fernández-Suárez J. López-Carmona A. Hofmann M. Romer R. L. 《International Journal of Earth Sciences》2018,107(3):985-1004
International Journal of Earth Sciences - In this study, we report U–Pb Laser Ablation ICP-MS zircon and ID-TIMS monazite ages for peraluminous granitoid plutons... 相似文献