全文获取类型
收费全文 | 2005篇 |
免费 | 187篇 |
国内免费 | 344篇 |
专业分类
测绘学 | 79篇 |
大气科学 | 42篇 |
地球物理 | 171篇 |
地质学 | 732篇 |
海洋学 | 146篇 |
天文学 | 1165篇 |
综合类 | 48篇 |
自然地理 | 153篇 |
出版年
2024年 | 13篇 |
2023年 | 28篇 |
2022年 | 45篇 |
2021年 | 39篇 |
2020年 | 46篇 |
2019年 | 46篇 |
2018年 | 32篇 |
2017年 | 33篇 |
2016年 | 35篇 |
2015年 | 65篇 |
2014年 | 98篇 |
2013年 | 81篇 |
2012年 | 84篇 |
2011年 | 104篇 |
2010年 | 93篇 |
2009年 | 173篇 |
2008年 | 166篇 |
2007年 | 154篇 |
2006年 | 184篇 |
2005年 | 169篇 |
2004年 | 152篇 |
2003年 | 131篇 |
2002年 | 101篇 |
2001年 | 84篇 |
2000年 | 78篇 |
1999年 | 79篇 |
1998年 | 84篇 |
1997年 | 29篇 |
1996年 | 22篇 |
1995年 | 19篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
排序方式: 共有2536条查询结果,搜索用时 15 毫秒
71.
This paper presents a critical and reflexive account of using Q methodology in human geography. Q methodology has a long pedigree in psychological, political and sociological research, but is only recently beginning to be used by human geographers. We discuss, in particular, the parts of the process(es) of Q methodology that are often glossed over in the literature, through reflecting on our learning in using Q within a project examining the use and production of environmental science by NGOs. We conclude that Q may be a useful supplement to existing methods in human geography, as long as it is used creatively and reflexively and with full awareness of its interpretative dimensions. 相似文献
72.
73.
The effect of fluids on recrystallization behaviour is well known; however, the detailed microscale distribution of fluid in grain boundaries and the influence of fluid on grain boundary migration are still unresolved. In this study, in‐situ deformation experiments in transmitted light microscopy were undertaken, as this allows continuous and direct observation of the whole range of processes involved in fluid‐assisted grain boundary migration. A new see‐through deformation apparatus was developed to enable the control of fluid pressure. Bischofite containing small amounts of aqueous fluid was deformed at temperatures between 50 and 90 °C, over a range of fluid pressure from 0.5 to 1 MPa, and strain rates of 5 × 10?6 to 1 × 10?4 s?1. The rates of grain boundary migration were measured at different temperatures and strain rates. Detailed observations during and after the deformation illustrate the evolution of migrating fluid‐filled grain boundaries and show that the incorporation of fluids from inclusions as well as their pinch‐off is dependent on the grain boundary velocity, the thickness of the grain boundary and the size and shape of the inclusions. Direct evidence is presented for the contraction of the grain boundary fluids into isolated inclusions after equilibrium conditions are attained. 相似文献
74.
Janet M. Hergt L. Paul Bédard Etienne Deloule Kathryn L. Linge Paul J. Sylvester Michael Wiedenbeck Jon D. Woodhead 《Geostandards and Geoanalytical Research》2005,29(1):5-52
The articles that comprise this critical review serve to draw attention to research papers published in specific fields of interest during 2003, provide critical comment on the relevance and importance of individual publications in these fields, and offer an overview of the comparative importance of advances in particular areas. In this way, these articles aim to assist experts in the field by keeping them informed of relevant recent publications, as well as providing an important resource for students or early career researchers who are embarking on studies in an area new to them. This year, five papers provide summaries of developments in bulk sample determinations employing (1) ICP-AES and ICP-MS (trace elements), (2) XRF and atomic absorption spectrometry and INAA, (3) isotope ratio measurements (TIMS, MC-ICP-MS, ICP-MS, ToF), as well as in situ measurements conducted using (4) secondary ion mass spectrometry and (5) laser ablation ICP-MS (trace element and isotope ratio determinations). 相似文献
75.
Roger Guérin 《Hydrogeology Journal》2005,13(1):251-254
76.
成熟勘探的矿集区非常有必要开展新一轮的找矿,但矿床模式的局限和大埋藏深度等困难制约了这些地区的预测性找矿发现。促进其预测性找矿发现的关键战略包括:勘查模型的创新、勘查技术的创新和各种信息的综合集成预测。勘查模型的创新必须包含基于地球动力学剖析的新成矿概念,动力学数值模拟是有效的创新手段之一;勘查技术创新的主要目的是加大探测深度和提高探测与解释的准确性,必须以详细可靠的地质资料为基础;综合信息集成是利用GIS和知识驱动及数据驱动的方法充分提取各种数据中的有用信息,集成为更加可靠的预测图。在这种思想的指导下,我们在铜陵凤凰山矿田进行了预测和勘查,并成功地发现了深部的隐伏矿床。 相似文献
77.
Low-order stabilized finite element for the full Biot formulation in soil mechanics at finite strain
Lluís Monforte Pedro Navas Josep Maria Carbonell Marcos Arroyo Antonio Gens 《国际地质力学数值与分析法杂志》2019,43(7):1488-1515
This article presents a novel finite element formulation for the Biot equation using low-order elements. Additionally, an extra degree of freedom is introduced to treat the volumetric locking steaming from the effective response of the medium; its balance equation is also stabilized. The accuracy of the proposed formulation is demonstrated by means of numerical analyses. 相似文献
78.
Analytical solutions for advective–dispersive solute transport in double‐layered finite porous media
Peter John Cleall 《国际地质力学数值与分析法杂志》2011,35(4):438-460
Analytical solutions for advection and dispersion of a conservative solute in a one‐dimensional double‐layered finite porous media are presented. The solutions are applicable to five scenarios that have various combinations of fixed concentration, fixed flux and zero concentration gradient conditions at the inlet and outlet boundaries that provide a wide number of options. Arbitrary initial solute concentration distributions throughout the media can be considered via explicit formulations or numerical integration. The analytical solutions presented have been verified against numerical solutions from a finite‐element‐based approach and an existing closed‐form solution for double‐layered media with an excellent correlation being found in both cases. A practical application pertaining to advective transport induced by consolidation of underlying sediment layers on contaminant movement within a capped contaminated sediment system is presented. Comparison of the calculated concentrations and fluxes with alternative approaches clearly illustrates the need to consider advection processes. Consideration of the different features of contaminant transport due to varying pore‐water velocity fields in primary consolidation and secondary consolidation stages is achieved via the use of non‐uniform initial concentration distributions within the proposed analytical solutions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
79.
Application research of enhanced in-situ micro-ecological remediation of petroleum contaminated soil
下载免费PDF全文
![点击此处可从《地下水科学与工程》网站下载免费的PDF全文](/ch/ext_images/free.gif)
ZHANG Sheng ZHANG Cui-yun HE Ze CHEN Li ZHANG Fa-wang YIN Mi-ying NING Zhuo SUN Zhen-hua ZHEN Shi-jun 《地下水科学与工程》2016,4(3):157-164
Experimental study of enhanced in-situ micro-ecological remediation of petroleum contaminated loess soil was carried out in Zhongyuan oil production areas, and the enhanced in-situ micro-ecological remediation technique includes optimistic in-situ microbial communities, physical chemistry methods, alfalfa planting and regulation of soil environmental elements. Experiments showed that the oil content in the contaminated soil with oil content about 2 898.25 mg/kg can be reduced about 98.61% after in-situ micro-ecological remediation for 99 days, which demonstrated the effectiveness of in-situ micro-ecological remediation methods for petroleum contaminated soil in central plains of China, and explored the practical and feasible application of these methods. 相似文献
80.
以固体废弃物粉煤灰基地质聚合物为基本骨架,通过水热合成法将其原位转化为自支撑Na P型沸石分子筛型体,并研究了水热过程中碱液浓度、碱液体积、水热温度和水热时间对NaP型沸石分子筛结晶程度、形貌和机械强度的影响,得到粉煤灰基地质聚合物原位转化Na P型沸石分子筛型体的适宜条件为水热温度100℃、NaOH浓度2.0mol/L、NaOH体积50 m L、水热时间24 h。所得Na P型沸石分子筛型体的抗压强度为23.21 MPa,BET比表面积为50.46 m~2/g,已达到工业生产P型沸石的水平。该法工艺简单,环境友好,可控成型。在此方法的基础上通过改变原料配比和反应条件,可以合成其他类型的沸石分子筛型体。 相似文献