全文获取类型
收费全文 | 10813篇 |
免费 | 1929篇 |
国内免费 | 2576篇 |
学科分类
地球科学 | 15318篇 |
出版年
2024年 | 60篇 |
2023年 | 195篇 |
2022年 | 428篇 |
2021年 | 518篇 |
2020年 | 389篇 |
2019年 | 525篇 |
2018年 | 583篇 |
2017年 | 517篇 |
2016年 | 584篇 |
2015年 | 515篇 |
2014年 | 675篇 |
2013年 | 640篇 |
2012年 | 741篇 |
2011年 | 723篇 |
2010年 | 760篇 |
2009年 | 728篇 |
2008年 | 695篇 |
2007年 | 671篇 |
2006年 | 594篇 |
2005年 | 466篇 |
2004年 | 418篇 |
2003年 | 404篇 |
2002年 | 356篇 |
2001年 | 333篇 |
2000年 | 353篇 |
1999年 | 334篇 |
1998年 | 283篇 |
1997年 | 277篇 |
1996年 | 232篇 |
1995年 | 223篇 |
1994年 | 183篇 |
1993年 | 184篇 |
1992年 | 133篇 |
1991年 | 85篇 |
1990年 | 74篇 |
1989年 | 72篇 |
1988年 | 59篇 |
1987年 | 55篇 |
1986年 | 40篇 |
1985年 | 26篇 |
1984年 | 25篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 14篇 |
1980年 | 18篇 |
1979年 | 12篇 |
1977年 | 9篇 |
1971年 | 8篇 |
1970年 | 10篇 |
1969年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
The Siberian Solar Radio Telescope: the current state of the instrument,observations, and data 总被引:2,自引:0,他引:2
Grechnev V.V. Lesovoi S.V. Smolkov G. Ya. Krissinel B.B. Zandanov V.G. Altyntsev A.T. Kardapolova N.N. Sergeev R.Y. Uralov A.M. Maksimov V.P. Lubyshev B.I. 《Solar physics》2003,216(1-2):239-272
The Siberian Solar Radio Telescope (SSRT) is one of the world's largest solar radio heliographs. It commenced operation in
1983, and since then has undergone several upgrades. The operating frequency of the SSRT is 5.7 GHz. Since 1992 the instrument
has had the capability to make one-dimensional scans with a high time resolution of 56 ms and an angular resolution of 15 arc sec.
Making one of these scans now takes 14 ms. In 1996 the capability was added to make full, two-dimensional images of the solar
disk. The SSRT is now capable of obtaining images with an angular resolution of 21 arc sec every 2 min. In this paper we describe
the main features and operation of the instrument, particularly emphasizing issues pertaining to the imaging process and factors
limiting data quality. Some of the data processing and analysis techniques are discussed. We present examples of full-disk
solar images of the quiet Sun, recorded near solar activity minimum, and images of specific structures: plages, coronal bright
points, filaments and prominences, and coronal holes. We also present some observations of dynamic phenomena, such as eruptive
prominences and solar flares, which illustrate the high-time-resolution observations that can be done with this instrument.
We compare SSRT observations at 5.7 GHz, including computed `light curves', both morphologically and quantatively, with observations
made in other spectral domains, such as 17 GHz radio images, Hα filtergrams and magnetograms, extreme-ultraviolet and X-ray
observations, and dynamic radio spectra. 相似文献
2.
高从堦 《中国海洋湖沼学报》2003,21(1):40-45
Seawater desalination has been people‘s fond dream since ancient times,the dream is now becoming a reality.This paper presents a brief development history of reverse osmosis.Much attention was paid to innovative development in mebranes,modules.equipments and applied technology,including asymmetric and composite membranes,spiral-wound element and hollow fiber module,energy recovery equipments and different technological processes.The extension of reverse osmosis,such as desalination,pre-concentration,integrated processes and nanofiltration,is also briefly mentioned. 相似文献
3.
Radio astronomy experiments designed to probe the interplanetary plasma close to the Sun have been carried out at the wavelength = 2.92 m using the occultation method. The experiments are based on a modification of the occultation method by which the sources, in this case quasars, are used to measure the radial dependence of the apparent source size, the scattering angle (R). The radial dependence of this source size (R) reveals that an anomalous enhancement in the scattering appears at radial distances from about 16 to 30 R
, which is associated with the solar wind transsonic region. It is shown by analysis of the theoretical equations that the radial profiles of both the source size (R) and the scintillation index m(R) are consistent in the near solar interplanetary medium (R 40 R
). Combining these two independent applications of the occultation method extends the range of the investigation and provides a powerful new diagnostic of the solar wind transsonic region. 相似文献
4.
SubunitcompositionandchromophorecontentofR-phycocyaninandallophycocyaninfromPorphyrahaitanensis¥GaoHongfeng;CaoWendaandJiMing... 相似文献
5.
黄河三角洲地貌环境体系 总被引:4,自引:0,他引:4
黄河三角洲是由三角洲上部冲积平原一下部冲积海积平原(超潮滩)─周边潮滩三个区带的地貌系列构成.它们之间形成三条地貌环境岸线,是一个复杂而统一的陆上─潮滩堆积地貌体系.该体系研究对三角洲发育.环境及其开发利用有一定理论和实践意义. 相似文献
6.
7.
8.
Ya. A. Virolainen Yu. M. Timofeev A. V. Polyakov H. Steele M. Newchurch 《Izvestiya Atmospheric and Oceanic Physics》2006,42(6):752-764
A statistical ensemble of microphysical parameters of the background stratospheric aerosol at altitudes of 15 to 30 km is modeled on the basis of experimental data. The aerosol attenuation coefficients (AACs) in the wavelength range 0.38–16.3 μm are calculated for all realizations of the ensemble by algorithms of the Mie theory. Analysis of correlations between the AACs and the microphysical parameters indicate that the AAC correlates most strongly with the total volume V and area S of all particles. The errors of determining the microphysical parameters from AAC measurements are analyzed via the method of linear regression. It is shown that, if the AAC is measured with an error of 5%, the errors of determining both the particle size distribution (PSD) for particles with sizes of 0.4 to 4 μm and the parameter S are an order of magnitude smaller than the prior uncertainty, whereas the error of determining V is two orders of magnitude smaller than the prior uncertainty. Schemes of AAC measurements with the SAGE III, ISAMS, CLAES, HALOE instruments and an IR interferometer in the visible and IR regions are discussed. It is shown that combining the schemes makes it possible to extend the range of particle sizes for which the PSD is retrieved with a satisfactory accuracy and to increase the accuracy of determining S and V substantially and the accuracy of determining the total number of particles N opt to a lesser extent. Examples of interpreting AAC measurements carried out simultaneously with the SAGE III and HALOE instruments within the same spatial region are presented. A systematic discrepancy between vertical profiles of S and V obtained from SAGE III and HALOE measurements is revealed. 相似文献
9.
10.