全文获取类型
收费全文 | 177篇 |
免费 | 15篇 |
国内免费 | 34篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 34篇 |
地球物理 | 48篇 |
地质学 | 70篇 |
海洋学 | 10篇 |
天文学 | 15篇 |
综合类 | 4篇 |
自然地理 | 43篇 |
出版年
2023年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 11篇 |
2007年 | 10篇 |
2006年 | 20篇 |
2005年 | 24篇 |
2004年 | 13篇 |
2003年 | 5篇 |
2002年 | 16篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有226条查询结果,搜索用时 78 毫秒
11.
12.
这次泥浆体流变试验的比测使用了五种不同规格的旋转式粘度计,并把其测试结果与毛管式粘度计的测试结果作了对比。对比结果表明:若用旋转式粘度计测试具有非牛顿体特性的泥浆体,应尽可能采用具有转筒半径比(α=外筒半径R_c/内筒半径R_b)较小的测试室;若是用具有α>1.05的测试室测试,所得的数据则应作特殊处理。毛管式、旋转式两种粘度计的测试结果基本一致,并具相仿的精度。测试结果的离散程度超过仪器的测试误差。这有待进一步研究、查明原因。 相似文献
13.
Survey Group of Wuzhai Earthquake 《山西地震》1995,(2):42-47
本文介绍了对1993的9月11日五寨4.8ML地震的考察情况,确定宏观震中在五寨县丰兑坡与河曲县土沟村一带,震中烈度为6度。计算得出本次地震的总经济损失约15万元。 相似文献
14.
Laihunite Research Group 《中国地球化学学报》1982,1(1):105-114
Laihuite reported in the present paper is a new iron silicate mineral found in China with the following characteristics:
- This mineral occurs in a metamorphic iron deposit, associated with fayalite, hypersthene, quartz, magnetitc, etc.
- The mineral is opaque, black in colour, thickly tabular in shape with luster metallic to sub-metallic, two perfect cleavages and specific gravity of 3.92.
- Its main chemical components are Fe and Si with Fe3+>Fe2+. The analysis gave the formula of Fe Fe 1.00 3+ ·Fe 0.58 2+ ·Mg 0.03 2+ ·Si0.96O4.
- Its DTA curve shows an exothermic peak at 713°C.
- The mineral has its own infrared spectrum distinctive from that of other minerals.
- This mineral is of orthorhombic system; space group:C 2h /5 ?P21/c; unit cell:α=5.813ű0.005,b=4.812ű0.005,c=10.211ű0.005,β=90.87°.
- The Mössbauer spectrum of this mineral is given, too.
15.
16.
Russian Federation/ United States Calibration Working Group 《Pure and Applied Geophysics》2001,158(1-2):59-77
—?Joint Research Program of Seismic Calibration of the International Monitoring System (IMS) in Northern Eurasia and North America has been signed by the Nuclear Treaty Programs Office (NTPO), Department of Defense USA, and the Special Monitoring Service (SMS) of the Ministry of Defense, Russian Federation (RF). Under the Program historical data from nuclear and large chemical explosions of known location and shot time, together with appropriate geological and geophysical data, has been used to derive regional Pn/P travel-time tables for seismic event location within the lower 48 States of the USA and the European part of the RF. These travel-time tables are up to 5?seconds faster in shields than the IASPEI91 tables, and up to 5?seconds slower in the Western USA. Relocation experiments using the regional Pn travel-time curves and surrogate networks for the IMS network generally improved locations for regional seismic events. The distance between true and estimated location (mislocation) was decreased from an average of 18.8?km for the IASPEI91 tables to 10.1?km for the regional Pn travel-time tables. However, the regional travel-time table approach has limitations caused by travel-time variations inside major tectonic provinces and paths crossing several tectonic provinces with substantially different crustal and upper mantle velocity structure.¶The RF members of the Calibration Working Group (WG): Colonel Vyacheslav Gordon (chairman); Dr. Prof. Marat Mamsurov, and Dr. Nikolai Vasiliev. The US members of the WG: Dr. Anton Dainty (chairman), Dr. Douglas Baumgardt, Mr. John Murphy, Dr. Robert North, and Dr. Vladislav Ryaboy. 相似文献
17.
叙述了1989大同—阳高地震的基本情况,回顾了此次地震现场的分析预报工作。按照《地震现场工作大纲和震情分析指南》所确定的原则,采用国内常用的一些方法,对此次地震的类型、震前活动、地震趋势、余震活动等做了分析。并对几次强余震的预报过程进行了讨论。 相似文献
18.
One of the fundamental questions concerning the nature and prediction of the oceanic states in the equatorial eastern Pacific is how the turnabout from a cold water state (La Nina) to a warm water state (El Nino) takes place, and vice versa. Recent studies show that this turnabout is directly linked to the interannual thermocline variations in the tropical Pacific Ocean basin. An index, as an indicator and precursor to describe interannual thermocline variations and the turnabout of oceanic states in our previous paper (Qian and Hu, 2005), is also used in this study. The index, which shows the maximum subsurface temperature anomaly (MSTA), is derived from the monthly 21-year (1980-2000) expendable XBT dataset in the present study. Results show that the MSTA can be used as a precursor for the occurrences of El Nino (or La Nina) events. The subsequent analyses of the MSTA propagations in the tropical Pacific suggest a one-year potential predictability for El Nino and La Nina events by identifying ocean temperature anomalies in the thermocline of the western Pacific Ocean. It also suggests that a closed route cycle with the strongest signal propagation is identified only in the tropical North Pacific Ocean. A positive (or negative) MSTA signal may travel from the western equatorial Pacific to the eastern equatorial Pacific with the strongest signal along the equator. This signal turns northward along the tropical eastern boundary of the basin and then moves westward along the north side of off-equator around 16°N. Finally, the signal returns toward the equator along the western boundary of the basin. The turnabout time from an El Nino event to a La Nina event in the eastern equatorial Pacific depends critically on the speed of the signal traveling along the closed route, and it usually needs about 4 years. This finding may help to predict the occurrence of the El Nino or La Nina event at least one year in advance. 相似文献
19.
Mariusz Majdaski Elena Kozlovskaya Marek Grad SUDETES Working Group 《Tectonophysics》2007,437(1-4):17-36
The SUDETES 2003 wide-angle refraction/reflection experiment covered the area of the south-western Poland and the northern Bohemian Massif. The good quality data that were gathered combined with the data from previous experiments (POLONAISE'97, CELEBRATION 2000) allowed us to prepare a 3D seismic model of the crust and uppermost mantle for this area. We inverted travel times of both refracted and reflected P waves using the JIVE3D package. This allowed us to obtain a model of P-wave velocity distribution as well as the shape of major boundaries in the crust. We also present a detailed uncertainty analysis for both the boundary depths and the velocity field. In doing the uncertainty analysis we found an interesting, strong dependence between uncertainty and inversion scheme (order of used phases). We also compared the model with surface geology and found good correlation between velocity inhomogeneities in the uppermost crust (down to 2 km) and major geological units. The higher velocity lower crust (6.9–7.2 km/s) could result from remelting of the lower crust or magmatic underplating. 相似文献
20.
爆炸影响降水的观测分析 总被引:1,自引:0,他引:1
大气物理研究所三室原理组 《大气科学》1976,(1):62-67
本文对“炮响雨落”的现象进行了实验验证。初步结果表明:在一定云雨条件下,炮击后可能促使未降水积状云产生降水,也可能促使已降水云的降水参量增大,这些变化发生迅速,但维持时间不长。并指出炮击促进云体降水的作用可能是通过改变支托水滴的气流造成的。在适当条件下,通过炮击影响气流的瞬时作用,可能触发云内不稳定能量释放,造成持续下沉,破坏云的发展,从而防止冰雹灾害。 相似文献