全文获取类型
收费全文 | 590篇 |
免费 | 123篇 |
国内免费 | 51篇 |
专业分类
测绘学 | 38篇 |
大气科学 | 30篇 |
地球物理 | 102篇 |
地质学 | 466篇 |
海洋学 | 32篇 |
天文学 | 63篇 |
综合类 | 9篇 |
自然地理 | 24篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 15篇 |
2018年 | 11篇 |
2017年 | 10篇 |
2016年 | 63篇 |
2015年 | 40篇 |
2014年 | 44篇 |
2013年 | 41篇 |
2012年 | 47篇 |
2011年 | 42篇 |
2010年 | 23篇 |
2009年 | 47篇 |
2008年 | 59篇 |
2007年 | 34篇 |
2006年 | 33篇 |
2005年 | 48篇 |
2004年 | 24篇 |
2003年 | 22篇 |
2002年 | 24篇 |
2001年 | 18篇 |
2000年 | 15篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有764条查询结果,搜索用时 953 毫秒
151.
Appropriate Sampling for Optimised Measurement (ASOM), rather than the Theory of Sampling (TOS) Approach,to Ensure Suitable Measurement Quality: A Refutation of Esbensen and Wagner (2014)
下载免费PDF全文
![点击此处可从《Geostandards and Geoanalytical Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Michael H. Ramsey 《Geostandards and Geoanalytical Research》2016,40(4):571-581
The ‘Appropriate Sampling for Optimised Measurement’ (ASOM) approach considers measurement to be the focus of the sampling process, and sampling to be only the first part of the measurement process. To achieve ASOM, the uncertainty of measurements, including its contribution from sampling, needs to be estimated and optimised in order to achieve fitness‐for‐purpose. Such samples are then ‘sufficiently’ representative. The ‘Theory of Sampling’ (TOS) focuses on the processes of primary sampling and sample preparation and assumes that samples are ‘representative’ if they are correctly prepared by nominally ‘correct’ protocols. It defines around ten sampling ‘errors’, which are either modelled or minimised to improve sampling quality. It is argued that the ASOM approach is more effective in achieving appropriate measurement quality than in applying TOS to just the first part of the measurement process. The comparison is made less effective by the different objectives, scopes, terminology and assumptions of the two approaches. ASOM can be applied to in situ materials that are too variable to be modelled accurately, or where sources of uncertainty are unsuspected. The proposed integration of ASOM with TOS (Esbensen and Wagner 2014, Trends in Analytical Chemistry, 57, 93–106) is therefore effectively impossible. However, some TOS procedures can be useful within the ASOM approach. 相似文献
152.
Elimination of Interferences in the Determination of Palladium,Platinum and Rhodium Mass Fractions in Moss Samples using ICP‐MS/MS
下载免费PDF全文
![点击此处可从《Geostandards and Geoanalytical Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Terhi Suoranta Syed N. H. Bokhari Thomas Meisel Matti Niemelä Paavo Perämäki 《Geostandards and Geoanalytical Research》2016,40(4):559-569
Moss samples (Pleurozium schreberi) exposed to traffic‐related emission of Pd, Pt and Rh were analysed in this study. Successful elimination of interferences was achieved in the determination of Pd, Pt and Rh mass fractions in these samples using inductively coupled plasma‐tandem mass spectrometry (ICP‐MS/MS). Based on the results, a reliable determination of Pd, Pt and Rh mass fractions in microwave‐digested moss samples was obtained using ammonia (10% NH3 in He) in the collision/reaction cell when 103Rh was measured either on‐mass (103→103) or with mass‐shift (103→171) and mass‐shifts for 108Pd (108→159) and 195Pt (195→229) were used. The ICP‐MS/MS procedure was validated using BCR‐723 (road dust) as a reference material. In addition, a good agreement between the ICP‐MS/MS results and the results obtained with cloud point extraction and quadrupole ICP‐MS was observed for the moss samples. 相似文献
153.
Development of a New Method of Extraction of Interstitial Water from Low‐Porosity Consolidated Sediments Recovered During Super‐Deep Drilling Projects
下载免费PDF全文
![点击此处可从《Geostandards and Geoanalytical Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tomohiro Toki Harue Masuda Harunur Rashid Sebastian Hammerschmidt Ryuichi Shinjo 《Geostandards and Geoanalytical Research》2016,40(2):291-300
During the Integrated Ocean Drilling Program (IODP) Expedition 338, several methods were tested for the extraction of interstitial water in consolidated, low‐porosity deep‐sea sediments from Site C0002 in the Kumano Basin. On the basis of those tests, we propose a modified ground rock interstitial normative determination (GRIND) method of extraction of interstitial water. In separate runs of the new method, sediment samples were ground in a ball mill with either ultrapure water or a solution of HNO3. The interstitial water was then extracted with a conventional squeezer. Sufficient solution was extracted by this method to analyse most major and a few minor components of interstitial water that were comparable to those previously reported for samples extracted by the conventional squeezing method. The new method requires much smaller amounts of sediment than that of the conventional method and will be useful for analysis of samples recovered during super‐deep drilling programmes. 相似文献
154.
Julienne R. Emry Alison Olcott Marshall Craig P. Marshall 《Geostandards and Geoanalytical Research》2016,40(1):29-47
Raman hyperspectral imaging is becoming a popular technique to analyse geological materials. Autofluorescence can affect the quality of the spectra that comprise hyperspectral data sets. Few studies have addressed potential misinterpretation of Raman images from hyperspectral data sets affected by autofluorescence. Additionally, little work has been done to develop methods for identifying the spatial distribution of spectra affected by autofluorescence. This study illustrates how autofluorescence may lead to misinterpretation of the distribution of materials based on intensity at a point images. A method is proposed utilising signal to axis analysis to create images that identify regions affected by autofluorescence. Post‐processing baseline correction is often used to address autofluorescence, and most software programs utilise a form of partial least squares regression modelling based on a subjective choice of polynomial order. This study shows that an inappropriate choice of polynomial order can introduce error, which may lead to misinterpretation of Raman images. A signal to axis analysis method is proposed to statistically compare seemingly ‘appropriate’ baseline correction trials. Although post‐processing of hyperspectral data sets and creating Raman images seem simple, data quality issues such as autofluorescence must be considered. If baseline correction is deemed necessary, it should be addressed as an experiment involving statistical comparison. 相似文献
155.
156.
Matlab稳健回归法在FD-3019γ测井仪校准中的应用 总被引:1,自引:0,他引:1
简要介绍了FD-3019γ测井仪的校准方法,即Matlab稳健回归法及其抗差性。通过一个实例对比了Matlab稳健回归法和最小二乘法建立的一元线性回归方程,结果表明Matlab稳健回归法较之最小二乘法更为准确。 相似文献
157.
近年来,数字校园继数字地球、数字城市之后成为各高校研究的热点,三维数字校园虚拟系统构建平台多样、方法多元,却鲜有基于国内自主产权的MapGIS K9数字校园系统。因此,本文以某农业大学(南校区)为研究对象,对三维数字校园虚拟系统进行设计与实现。利用南方CASS、3DS Max、MapGIS K9及其他相关软件,通过资料收集整理、地理信息测量采集、建立1:500校园数字地形图、建立属性数据库、三维建模、多平台融合、交互式设计等一系列步骤,实现了某农业大学(南校区)三维数字校园虚拟系统的三维可视化和信息查询、测距、校园导航、自由路径游览、漫游视频录制的交互式功能,可以有效进行校园建筑属性信息查询与部分管理。 相似文献
158.
Abstract. Sponges from muddy and dctritic bottoms along the coasts of Liguria and Tuscany (Western Méditerranean) were studied to 700 m depth. The distribution of the 66 species identified was compared with depth, geographic location, as well as type of bottom and benthic community in order to determine whether a typical sponge fauna exists in these environments. The most common species (Suberites carnosus, S.ficus, Thenea muricata) are characteristic soft bottom dwellers, but the remaining sponge fauna seems to be linked to the presence of small patches of hard substrate scattered on these bottoms. As a consequence, the neighbouring hard bottom biocoenoses may remarkably affect the composition of this fauna by an export of larvae. Many species are clearly eurybathic, but most were recorded between 50 and 200 m. Type and size of the available substrate for sponge settlement and growth are apparently the most important Écological factors affecting the studied fauna. 相似文献
159.
For most of the year, a dry‐bed desert wash is void of water flow. Intensive rain events, however, could trigger significant flash floods that bring about highly complicated hydrodynamics and morphodynamics processes within a desert stream. We present a fully coupled three‐phase flow model of air, water, and sediment to simulate numerically the propagation of a flash flood in a field‐scale fluvial desert stream, the so‐called Tex Wash located in the Mojave Desert, California, United States. The turbulent flow of the flash flood is computed using the three‐dimensional unsteady Reynolds‐averaged Navier–Stokes equations closed with the shear stress transport k ? ω model. The free surface of the flash flood at the interface of air and water phases is computed with the level‐set method, which enables instantaneous tracking of the water surface as the flash flood propagates over the dry bed of the desert stream. The evolution of the desert fluvial stream9;s morphology, due to the action of the propagating flash flood on the mobile bed, is calculated using a Eulerian morphodynamics model based on the curvilinear immersed boundary method. The capabilities of the proposed numerical framework are demonstrated by applying it to simulate a flash flood event in a 0.65‐km ‐long reach of the Tex Wash, the intricate channel morphology of which is obtained using light imaging detection and ranging technology. The simulated region of the stream includes a number of bridge foundations. The simulation results of the model for the flash flood event revealed the formation of a highly complex flow field and scour patterns within the stream. Moreover, our simulation results showed that most scour processes take place during the steady phase of the flash flood, that is, after the flash flood fills the stream. The transient phase of the flash flood is rather short and contributes to a very limited amount of erosion within the desert stream. 相似文献
160.