首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3772篇
  免费   1575篇
  国内免费   3289篇
测绘学   71篇
大气科学   5750篇
地球物理   1085篇
地质学   537篇
海洋学   675篇
天文学   329篇
综合类   69篇
自然地理   120篇
  2024年   4篇
  2023年   56篇
  2022年   179篇
  2021年   232篇
  2020年   207篇
  2019年   216篇
  2018年   258篇
  2017年   260篇
  2016年   255篇
  2015年   402篇
  2014年   439篇
  2013年   500篇
  2012年   505篇
  2011年   543篇
  2010年   460篇
  2009年   632篇
  2008年   328篇
  2007年   461篇
  2006年   385篇
  2005年   232篇
  2004年   178篇
  2003年   169篇
  2002年   200篇
  2001年   163篇
  2000年   137篇
  1999年   176篇
  1998年   120篇
  1997年   92篇
  1996年   96篇
  1995年   66篇
  1994年   59篇
  1993年   66篇
  1992年   72篇
  1991年   63篇
  1990年   47篇
  1989年   53篇
  1988年   63篇
  1987年   43篇
  1986年   49篇
  1985年   39篇
  1984年   23篇
  1983年   16篇
  1982年   17篇
  1981年   18篇
  1980年   10篇
  1979年   10篇
  1977年   4篇
  1976年   9篇
  1975年   4篇
  1971年   6篇
排序方式: 共有8636条查询结果,搜索用时 31 毫秒
1.
Izvestiya, Atmospheric and Oceanic Physics - This paper investigates the stability of a jet flow with a piecewise linear velocity profile in a rotating stratified atmosphere. The linearized set of...  相似文献   
2.
Doklady Earth Sciences - The results of an analysis of changes in the atmospheric air quality in Moscow during the lockdown period and the decline in business activity caused by the COVID-19...  相似文献   
3.
The 2018 typhoon season in the western North Pacific(WNP) was highly active, with 26 named tropical cyclones(TCs) from June to November, which exceeded the climatological mean(22) and was the second busiest season over the past twenty years. More TCs formed in the eastern region of the WNP and the northern region of the South China Sea(SCS). More TCs took the northeast quadrant in the WNP, recurving from northwestward to northward and causing heavy damages in China's Mainland(69.73 billion yuan) in 2018. Multiscale climate variability is conducive to an active season via an enhanced monsoon trough and a weakened subtropical high in the WNP. The large-scale backgrounds in 2018 showed a favorable environment for TCs established by a developing central Pacific(CP) El Ni?o and positive Pacific meridional mode(PMM)episode on interannual timescales. The tropical central Pacific(TCP) SST forcing exhibits primary control on TCs in the WNP and large-scale circulations, which are insensitive to the PMM. During CP El Ni?o years, anomalous convection associated with the TCP warming leads to significantly increased anomalous cyclonic circulation in the WNP because of a Gill-type Rossby wave response. As a result, the weakened subtropical high and enhanced monsoon trough shift eastward and northward, which favor TC genesis and development. Although such increased TC activity in 2018 might be slightly suppressed by interdecadal climate variability, it was mostly attributed to the favorable interannual background. In addition, high-frequency climate signals,such as intraseasonal oscillations(ISOs) and synoptic-scale disturbances(SSDs), interacted with the enhanced monsoon trough and strongly modulated regional TC genesis and development in 2018.  相似文献   
4.
Izvestiya, Atmospheric and Oceanic Physics - The phase shift between changes in the global surface temperature Tg and atmospheric CO2 content $${{q}_{{{\text{C}}{{{\text{O}}}_{2}}}}}$$ has been...  相似文献   
5.
Results obtained from simulating the propagation of infrasonic waves from the Chelyabinsk meteoroid explosion observed on February 15, 2013, are given. The pseudodifferential parabolic equation (PDPE) method has been used for calculations. Data on infrasonic waves recorded at the IS31 station (Aktyubinsk, Kazakhstan), located 542.7 km from the likely location of the explosion, have been analyzed. Six infrasonic arrivals (isolated clearly defined pulse signals) were recorded. It is shown that the first “fast” arrival (F) corresponds to the propagation of infrasound in a surface acoustic waveguide. The rest of the arrivals (T1–T5) are thermospheric. The agreement between the results of calculations based on the PDPE method and experimental data is satisfactory. The energy E of the explosion has been estimated using two methods. One of these methods is based on the law of conservation of the acoustic pulse I, which is a product of the wave profile area S/2 of the signal under analysis and the distance to its source E I [kt] = 1.38 × 10–10 (I [kg/s])1.482. The other method is based on the relation between the energy of explosion and the dominant period T of recorded signal E T [kt] = 1.02 × (T [s]2/σ)3/2, where σ is the dimensionless distance determining the degree of nonlinear effects during the propagation of sound along ray trajectories. According to the data, the explosion energy E I,T ranges from 1.87 to 32 kt TNT.  相似文献   
6.
Izvestiya, Atmospheric and Oceanic Physics - This paper summarizes the results of long-term (2004–2016) comprehensive experimental studies of microphysical parameters and the mass...  相似文献   
7.
The results of rocket and satellite measurements available in the literature of 5.3-μm nitric oxide emission in the upper atmosphere have been systematized and analyzed. Analytical dependences describing the height distribution of volumetric intensity of 5.3-μm emission of the NO molecule and its variations in a range of heights from 100 to 130 km as a function of the time of year, day, latitude, and solar activity have been obtained.  相似文献   
8.
A high-resolution dual-band terahertz (THz) radiometer was designed to measure vertical distributions of chemical elements in the middle atmosphere of the Tibetan Plateau. A forward simulation, which always should be conducted firstly for the development of a matching retrieval algorithm, has not been done before. We use two radiative transfer models, ARTS and AM, to simulate the water vapor, ozone and carbon monoxide spectra on the plateau based on the spectral design of the THz radiometer. The emission line characteristics of the three gases in this spectral band are identified. Reasons for the differences in the spectral simulations between the two models are analyzed for individual gases. The impact of several different spectral parameter settings on the simulations are evaluated through a series of sensitivity experiments. This study suggests that the ARTS is more suitable for the development of the THz radiometer retrieval algorithm. An optimal parameter setting of the ARTS for the three elements are given.  相似文献   
9.
Izvestiya, Atmospheric and Oceanic Physics - An investigation into mesoscale roll circulation and its transport characteristics in the atmospheric boundary layer (ABL) is carried out. The case...  相似文献   
10.
After the 1967 flight of the Venera-4 automatic interplanetary station (AIS), the study of planetary atmospheres became one of the key areas of scientific research at the Institute of Atmospheric Physics (IAPh), USSR Academy of Sciences. The goal of the Venera-4 mission was to deliver a descent vehicle into the atmosphere of Venus and study the physical parameters and chemical composition of the atmosphere. IAPh scientists published several articles on the analysis of these measurements, with A.M. Obukhov himself directly involved in writing some of these articles. An analysis of the properties of the Martian surface and atmosphere from the data of the Mars-2, Mars-3, and Mariner-9 missions in November–December 1971 set the stage for a series of studies on the atmospheric effects of Martian dust storms. Based on the study of the atmospheres of terrestrial planets, IAPh scientists developed a simple model for the nuclear winter phenomenon, i.e., a long-term cooling due to massive fires caused by nuclear explosions. Obukhov took a keen interest in this subject and participated in the publication of review articles on the possible atmospheric and climatic effects of a nuclear war. In another publication, Obukhov and his coauthors provided a theoretical analysis of the possible causes for the tail from Halley’s comet ripping off, as was observed in January 1986. The present article gives a brief overview of the IAPh works on Solar System research and on the possible consequences of a nuclear conflict, which were published in the 1960s–1980s while Obukhov was alive.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号