全文获取类型
收费全文 | 6507篇 |
免费 | 691篇 |
国内免费 | 1000篇 |
专业分类
测绘学 | 677篇 |
大气科学 | 392篇 |
地球物理 | 1136篇 |
地质学 | 2211篇 |
海洋学 | 604篇 |
天文学 | 1554篇 |
综合类 | 399篇 |
自然地理 | 1225篇 |
出版年
2024年 | 31篇 |
2023年 | 79篇 |
2022年 | 186篇 |
2021年 | 179篇 |
2020年 | 198篇 |
2019年 | 273篇 |
2018年 | 194篇 |
2017年 | 216篇 |
2016年 | 236篇 |
2015年 | 249篇 |
2014年 | 280篇 |
2013年 | 386篇 |
2012年 | 285篇 |
2011年 | 305篇 |
2010年 | 265篇 |
2009年 | 436篇 |
2008年 | 440篇 |
2007年 | 476篇 |
2006年 | 452篇 |
2005年 | 366篇 |
2004年 | 342篇 |
2003年 | 307篇 |
2002年 | 284篇 |
2001年 | 257篇 |
2000年 | 227篇 |
1999年 | 226篇 |
1998年 | 201篇 |
1997年 | 112篇 |
1996年 | 110篇 |
1995年 | 93篇 |
1994年 | 88篇 |
1993年 | 83篇 |
1992年 | 64篇 |
1991年 | 42篇 |
1990年 | 60篇 |
1989年 | 47篇 |
1988年 | 29篇 |
1987年 | 35篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 5篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1954年 | 4篇 |
排序方式: 共有8198条查询结果,搜索用时 31 毫秒
151.
现代抗震设计理论的发展过程 总被引:18,自引:0,他引:18
介绍了现代抗震设计理论的发展过程,基于性态的抗震设计理论的提出背景、发展情况及研究内容;详细介绍了基于性态的抗震设计理论的抗震设防方法;指出了基于性态的抗震设计理论与传统抗震设计理论的主要区别及特点。 相似文献
152.
153.
Introduction Greeting the coming of the 21st century, Professor HU Yu-xian and other Chinese scholars briefed the trend of earthquake engineering in China and aboard (HU, 1999; HU, ZHOU, 1999). The experiences and lessons learning from the destructive earthquakes in China and abroad in re-cent years, the damage action of the large velocity impulse in ground motion in near field in seis-mic design, numerous earthquake examples show that there are many weaknesses in aspects of earthquake p… 相似文献
154.
Introduction The rock medium shows mainly elastic character under low-temperature, low-pressure and external force for short duration, yet it shows rheologic property under high-temperature, high-pressure and long-time external force. It is reasonable that the rapid earthquake generating process lasted for tens seconds is analyzed by the elastic theory. As for the earthquake generating process for hundreds or thousand years, nevertheless, the rheologic property of rock must be taken into accou… 相似文献
155.
We prove that rays in linearly elastic anisotropic nonuniform media obey Fermat's principle of stationary traveltime. First, we formulate the concept of rays, which emerges from the Hamilton equations. Then, we show that these rays are solutions of the variational problem stated by Fermat's principle. This proof is valid for all rays except the ones associated with infection points on the phase-slowness surface. 相似文献
156.
土钉支护结构的优化设计 总被引:1,自引:1,他引:1
根据复形优化原理,提出了基于Bishop法的土钉支护结构的优化分析方法,编写了优化分析程序。工程实例计算表明,该方法是进行土钉优化设计的有效方法。 相似文献
157.
WangShicheng YeShuisheng ZhouDongdai 《中国地质大学学报(英文版)》2003,14(3):207-214
Metallogenic prognosis of synthetic information uses the geological body and the miaeral resource body as a statistical unit to interpret synthetically the information of geology, geophysics, geo-chemistry and remote sensing from the evolution of geology and puts all the information into one entire system by drawing up digitalized interpretation maps of the synthetic information. On such basis, differ-ent grades and types of mineral resource prospecting models and predictive models of synthetic informa-tion can be established. Hence, a new integrated prediction system will be formed of metallogenic prog-nosis (qualitative prediction), mineral resources statistic prediction (determining targets) and mlaeral resources prediction (determining resources amount). 相似文献
158.
Steven M Manson 《Geoforum》2003,34(1):17-20
Reitsma (A response to ‘simplifying complexity’. Geoforum 34 (1) (2003) 13), in response to the article ‘Simplifying Complexity’ (Manson, S.M., Simplifying complexity: a review of complexity theory. Geoforum 32 (3) (2001) 405), highlights a number of interesting and important aspects of complexity theory that invite further discussion. In particular, there are three areas of complexity research that are open to deeper exploration: (1) the width and breadth of ‘complexity’ defined as a scientific endeavor; (2) the role of theory relative to practice and their relationship with pattern and process in complex systems; and (3) the need for greater discussion and exploration in order to define the conceptual bounds of complexity theory. 相似文献
159.
The basic concepts of spectral and multiscale selective reconstruction of (geophysically relevant) vector fields on the sphere from error-affected data is outlined in detail. The reconstruction mechanism is formulated under the assumption that spectral as well as multiscale approximation is well-representable in terms of only a certain number of expansion coefficients at the various resolution levels. It is shown that spectral denoising by means of orthogonal expansions in terms of vector spherical harmonics reflects global a priori information of the noise (e.g., in form of a covariance tensor field), whereas multiscale signal-to-noise thresholding can be performed under locally dependent noise information within a multiresolution analysis in terms of spherical vector wavelets. An application of the multiscale formalism to Earth's magnetic field determination is presented. 相似文献
160.
本文介绍了一种在奔腾4处理器微机上Linux操作系统下的优化编译方法。作者通过查询、试验发现:使用Intel编译器优化中尺度模式MM5,能够使得MM5在奔腾4上的运行速度提高1.4~1.5倍。利用Intel编译器优化后的MM5模式,进行了三个月资料的计算,模式运行稳定。给出了一个使用Intel编译器和通常使用的PGI编译器分别编译的计算实例,对比表明:使用Intel编译器明显提高了运算速度,两种编译方法预报的降水场和形势场没有太大差异。 相似文献