全文获取类型
收费全文 | 968篇 |
免费 | 114篇 |
国内免费 | 246篇 |
专业分类
测绘学 | 44篇 |
大气科学 | 541篇 |
地球物理 | 75篇 |
地质学 | 73篇 |
海洋学 | 13篇 |
天文学 | 538篇 |
综合类 | 19篇 |
自然地理 | 25篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 25篇 |
2020年 | 16篇 |
2019年 | 37篇 |
2018年 | 22篇 |
2017年 | 22篇 |
2016年 | 23篇 |
2015年 | 32篇 |
2014年 | 40篇 |
2013年 | 33篇 |
2012年 | 46篇 |
2011年 | 36篇 |
2010年 | 27篇 |
2009年 | 88篇 |
2008年 | 47篇 |
2007年 | 79篇 |
2006年 | 86篇 |
2005年 | 76篇 |
2004年 | 84篇 |
2003年 | 53篇 |
2002年 | 80篇 |
2001年 | 54篇 |
2000年 | 55篇 |
1999年 | 58篇 |
1998年 | 59篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 19篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 4篇 |
排序方式: 共有1328条查询结果,搜索用时 531 毫秒
61.
关于热带大气低频振荡的一个简单模式与数值模拟 总被引:1,自引:0,他引:1
本文首先从观测事实分析了热带大气的低频振荡现象,然后从理论上加以研究。为此,本文建立了一个包括触发热源和CISK机制的三维线性模式,用此模式讨论了热带大气低频振荡的性质、结构、传播和动力学机制。从模式的计算结果得到了周期为30d左右以大约9 m/s的速度向东传播的低频振荡现象,这种振荡为Kelvin波型的响应和向西传播的Rossby波型的响应的结合。计算还表明,这种振荡的周期与触发热源的周期关系不大,这说明了热带大气的低频振荡是大气自身的固有振荡,它是大尺度运动与对流凝结加热相互作用的结果。 相似文献
62.
Feng Daxiong Chen Ruzhen Jiang Gengwang Luo Binghe Cui Yunshan 《Acta Meteorologica Sinica》1994,8(3):329-336
Two kinds of high efficient Agl pyrotechnics BR-88-5 and BR-91-Y have been developed.The tests in the cloud chamber show that the AgI ice nucleating effectiveness can reach up to 1015/g,and the BR-91-Y has even higher ice nucleating rate.Two kinds of foreign AgI pyrotechnics have been made according to the given formulations and also tested in the cloud chamber for comparison.X-ray diffraction analysis for the aerosols produced by burning BR-91-Y shows that AgI in acrosols still retains the hexagonal crystal form and the lattice parameters are smaller than those of pure AgI and other AgI composite nuclei,and closer to ice.Combining with the other tests,the reasons for the high efficiency of BR-91-Y have been discussed. 相似文献
63.
An atmospheric monitoring station is operated at Cape Matatula, American Samoa, by the Geophysical Monitoring for Climatic Change program under the National Oceanic and Atmospheric Administration. A nearly continuous record of condensation nucleus (CN) concentration and multiwavelength aerosol scattering extinction coefficient (sp) is available from mid-1977 to the present. This report presents the 1977–1983 data. The long-term mean of CN concentration is 274 cm-3 the long-term mean of sp (550 nm) is 1.54×10-5, and no significant long-term, annual, or diurnal trend is apparent in either data record. 相似文献
64.
Peng Wang Lei Liu Xichuan Liu Shuai Hu Shijun Zhao Wenming Ji Taichang Gao 《地球科学进展》1986,35(7):704-714
The accurate observation of the microphysical structure of cloud and precipitation plays an important role in understanding the formation of clouds and precipitation. In-situ measurement using measuring instruments carried by meteorological balloons is an effective way to obtain the microphysical properties of cloud and precipitation particles, which is a supplementary means for aircraft to observe cloud and precipitation particles. This observation method plays a more and more important role in in-situ measurement. According to the difference of the working principle of the existing balloon-borne cloud and precipitation particles probes, the detectors can be divided into particle impact-sampling sensors, particle imaging sensors, light-scattering sensors, light intensity attenuation sensors and charge measurement sensors. The working principles, key technologies and main advantages and disadvantages of typical instruments were summarized, and their applications to detailed cloud structure acquisition, cloud remote sensing method establishment, cloud and precipitation physical process research and parameterization, and scientific observation of thunderstorm clouds were briefly introduced. Finally, the development trend of balloon-borne cloud precipitation particle detectors was prospected, which will provide reference for related technical research and equipment development. 相似文献
65.
The use of cloud tracking techniques and storm identification procedures is proposed in this paper with the aim of predicting the evolution of cloud entities associated with the highest rainfall probability within a given meteorological scenario. Suitable algorithms for this kind of analysis are based on the processing of digital images in the thermal infrared (IR) band from geostationary satellites: a selection of such algorithms is described in some detail together with a few real case applications. Three heavy rainfall events have been selected for this purpose with reference to the extreme meteorological situation observed during Fall 1992 and 1993 over the Mediterranean area. A window from 30 to 60 °N and from 20 °W to 30 °E has been identified for the analysis of data from the radiometer on board the ESA Meteosat platform. In conclusion, the suitability of cloud tracking techniques for predicting the probability of heavy rainfall events is discussed provided that the former are associated with proper modeling of small scale rainfall distribution. 相似文献
66.
We consider the advantages of a formalism based on concept of the asymmetric continuum and we present some equivalence theorems
relating it to the asymmetric elasticity and to micropolar and micromorphic theories as founded by Nowacki, Cosserats and
Eringen.
We consider the basic processes in an asymmetric continuum which could be reduced to the point basic motions/deformations.
The co-action of spin and shear motions is assumed to play the main role in fracturing process, while the constitutive relation
between the antisymmetric stresses and rotations replaces the friction constitutive law. 相似文献
67.
山东省飞机增雨天气系统云水资源转化特征分析 总被引:5,自引:1,他引:5
利用水汽辐合法和水汽凝结法,对山东省1997-1999年春秋季18个降水过程的水汽辐合率、凝结率及降水效率等表征云水资源及其转化的特征量进行计算。分析了南方气旋、西北冷锋等主要降水天气系统以上特征量的地域分布和差别。可为人工增雨作业区域选择和航线设计提供气候背景。 相似文献
68.
69.
70.
The influence of various cloud parameters and the interactions with the ground albedo and the solar zenith angle have been studied by means of model simulations. The radiative transfer model suitable for a cloudy atmosphere as well as for a clear atmosphere has been developed on the basis of the Discrete Ordinate Method. This study leads to a general understanding for cloudy atmospheres: in the presence of a uniform cloud, the cloud scattering is dominant to molecular and aerosol scattering, and it is also wavelength-independent; the ratio of transmitted irradiance in a cloudy atmosphere to that in the background clear atmosphere is independent of cloud height and solar zenith angle. That’s to say, the radiation downwelling out of a cloud is quite isotropic; it decreases approximately exponentially with the cloud optical depth at a rate related to the ground albedo; the reflected irradiance at the top of the atmosphere is dependent on cloud optical depth as well as on solar zenith angle, but not on ground albedo for clouds of not very thin optical depth. 相似文献