全文获取类型
收费全文 | 17960篇 |
免费 | 3182篇 |
国内免费 | 4096篇 |
专业分类
测绘学 | 994篇 |
大气科学 | 3653篇 |
地球物理 | 5074篇 |
地质学 | 8435篇 |
海洋学 | 2487篇 |
天文学 | 769篇 |
综合类 | 1741篇 |
自然地理 | 2085篇 |
出版年
2024年 | 71篇 |
2023年 | 278篇 |
2022年 | 738篇 |
2021年 | 860篇 |
2020年 | 678篇 |
2019年 | 769篇 |
2018年 | 886篇 |
2017年 | 852篇 |
2016年 | 972篇 |
2015年 | 807篇 |
2014年 | 960篇 |
2013年 | 1076篇 |
2012年 | 952篇 |
2011年 | 989篇 |
2010年 | 1055篇 |
2009年 | 991篇 |
2008年 | 830篇 |
2007年 | 887篇 |
2006年 | 653篇 |
2005年 | 634篇 |
2004年 | 459篇 |
2003年 | 514篇 |
2002年 | 490篇 |
2001年 | 492篇 |
2000年 | 613篇 |
1999年 | 903篇 |
1998年 | 754篇 |
1997年 | 754篇 |
1996年 | 723篇 |
1995年 | 643篇 |
1994年 | 567篇 |
1993年 | 486篇 |
1992年 | 407篇 |
1991年 | 282篇 |
1990年 | 222篇 |
1989年 | 187篇 |
1988年 | 180篇 |
1987年 | 102篇 |
1986年 | 106篇 |
1985年 | 66篇 |
1984年 | 56篇 |
1983年 | 55篇 |
1982年 | 55篇 |
1981年 | 39篇 |
1980年 | 40篇 |
1979年 | 32篇 |
1978年 | 14篇 |
1977年 | 9篇 |
1974年 | 9篇 |
1958年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
951.
952.
953.
随着城市化进程的加大,测站周围障碍物的存在使风观测资料失去代表性、准确性和比较性。为定量化研究障碍物对风观测的影响,开展了河北沽源构筑物观测试验,通过对比构筑物修建前后各测点的风速风向资料,分析了障碍物对风速风向的影响。分析结果显示:1障碍物对风速的衰减作用与背景风速大小有关,风速越大,衰减作用越强;2背景风速在2~6m/s时,障碍物背风面测点风速衰减随距离增大而减小,在10倍障碍物高度距离处平均约衰减15%;背景风速大于6m/s时,背风面各测点风速衰减先增大后减小,在大约5倍障碍物高度的距离处衰减最大,10倍障碍物高度的距离处平均约衰减20%~30%;3障碍物的存在使主风向的风向频率减小,对风向的影响距离为6倍障碍物高度。 相似文献
954.
955.
Determination of the degree 120 time-variable gravity field in the Sichuan-Yunnan region using Slepian functions and terrestrial measurements
下载免费PDF全文
![点击此处可从《地震科学(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The terrestrial time-variable gravity measurements are characterized by a high signal-to-noise ratio and sensitivity to the sources of mass change in the Earth's crust. These gravity data have many applications, such as surface deformation, groundwater storage changes, and mass migration before and after earthquakes. Based on repeated terrestrial gravity measurements at 198 gravity stations in the Sichuan-Yunnan region (SYR) from 2015 to 2017, we determine a time series of degree 120 gravity fields using the localized spherical harmonic (Slepian) basis functions. Our results show that adopting the first 6 Slepian basis functions is sufficient for effective localized Slepian modeling in the SYR. The differences between two gravity campaigns at the same time of year show an obvious correlation with tectonic features. The degree 120 timevariable gravity models presented in this paper will benefit the study of the regional mass migration inside the crust of the SYR and supplement the existing geophysical models for the China Seismic Experimental Site. 相似文献
956.
粤北地区产铀岩体的铀矿化特征及其成矿机制探讨 总被引:7,自引:0,他引:7
粤北地区是中国花岗岩型铀矿最为重要的大型矿聚集区,其主要的产铀花岗岩体是诸广山岩体和贵东岩体,均为多期多阶段的复式岩体,主要以印支期和燕山期的花岗岩为主。粤北地区的铀矿床主要由诸广山的长江铀矿田、澜河铀矿田、鹿井铀矿田和贵东岩体的下庄铀矿田组成,根据铀的成矿特征可分为硅化带型、交点型和碱交代型。粤北地区的铀成矿流体主要来自于地幔,而不是以往认为的花岗岩浆期后热液,铀源主要是粤北产铀岩体的印支期花岗岩。因此在华南开展新一轮铀矿找矿时,跳出以往“沿带找矿”的老思路,聚焦于印支期岩浆作用与铀矿床的关系,并重点关注华南地区可能的地幔柱或热点区域。 相似文献
957.
Quality influencing factors of dispersion curves from short period dense arrays based on a convolutional neural network across the north section of the Xiaojiang fault area
下载免费PDF全文
![点击此处可从《地震科学(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Si Chen Rui Gao Zhanwu Lu Yao Liang Wei Cai Lifu Cao Zilong Chen Guangwen Wang 《地震科学(英文版)》2023,36(3):200-211
The number of dispersion curves increases significantly when the scale of a short-period dense array increases. Owing to a substantial increase in data volume, it is important to quickly evaluate dispersion curve quality as well as select the available dispersion curve. Accordingly, this study quantitatively evaluated dispersion curve quality by training a convolutional neural network model for ambient noise tomography using a short-period dense array. The model can select high-quality dispersio... 相似文献
958.
An accessible strong-motion dataset (PGA,PGV, and site vS30) of 2022 MS6.8 Luding,China Earthquake
下载免费PDF全文
![点击此处可从《地震科学(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jian Zhou Nan Xi Chuanchuan Kang Li Li Kun Chen Xin Tian Chao Wang Jifeng Tian 《地震科学(英文版)》2023,36(4):309-315
A MS6.8 earthquake occurred on 5th September 2022 in Luding county, Sichuan, China, at 12: 52 Beijing Time(4:52 UTC). We complied a dataset of PGA, PGV, and site vS30 of 73 accelerometers and 791 Micro-Electro-Mechanical System(MEMS)sensors within 300 km of the epicenter. The inferred vS30 of 820 recording sites were validated. The study results show that:(1)The maximum horizontal PGA and PGV reaches 634.1 Gal and 71.1 cm/s respectively.(2) Over 80% of records ar... 相似文献
959.
Yao Wang Chi-hui Guo Shu-rong Zhuang Xi-jie Chen Li-qiong Jia Ze-yu Chen Zi-long Xia Zhen Wu 《China Geology》2021,4(2):329-352
In the context of global climate change, geosciences provide an important geological solution to achieve the goal of carbon neutrality, China’s geosciences and geological technologies can play an important role in solving the problem of carbon neutrality. This paper discusses the main problems, opportunities, and challenges that can be solved by the participation of geosciences in carbon neutrality, as well as China’s response to them. The main scientific problems involved and the geological work carried out mainly fall into three categories: (1) Carbon emission reduction technology (natural gas hydrate, geothermal, hot dry rock, nuclear energy, hydropower, wind energy, solar energy, hydrogen energy); (2) carbon sequestration technology (carbon capture and storage, underground space utilization); (3) key minerals needed to support carbon neutralization (raw materials for energy transformation, carbon reduction technology). Therefore, geosciences and geological technologies are needed: First, actively participate in the development of green energy such as natural gas, geothermal energy, hydropower, hot dry rock, and key energy minerals, and develop exploration and exploitation technologies such as geothermal energy and natural gas; the second is to do a good job in geological support for new energy site selection, carry out an in-depth study on geotechnical feasibility and mitigation measures, and form the basis of relevant economic decisions to reduce costs and prevent geological disasters; the third is to develop and coordinate relevant departments of geosciences, organize and carry out strategic research on natural resources, carry out theoretical system research on global climate change and other issues under the guidance of earth system science theory, and coordinate frontier scientific information and advanced technological tools of various disciplines. The goal of carbon neutrality provides new opportunities and challenges for geosciences research. In the future, it is necessary to provide theoretical and technical support from various aspects, enhance the ability of climate adaptation, and support the realization of the goal of carbon peaking and carbon neutrality. 相似文献
960.