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   94篇
  免费   5篇
  国内免费   9篇
大气科学   28篇
地球物理   16篇
地质学   18篇
海洋学   20篇
天文学   19篇
综合类   4篇
自然地理   3篇
  2023年   1篇
  2022年   2篇
  2021年   5篇
  2020年   2篇
  2019年   2篇
  2018年   5篇
  2017年   4篇
  2016年   14篇
  2015年   5篇
  2014年   5篇
  2013年   7篇
  2012年   3篇
  2011年   5篇
  2010年   4篇
  2009年   4篇
  2008年   3篇
  2007年   4篇
  2006年   3篇
  2004年   2篇
  2003年   3篇
  2002年   1篇
  2001年   1篇
  2000年   3篇
  1999年   1篇
  1998年   1篇
  1997年   1篇
  1995年   4篇
  1994年   3篇
  1993年   2篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1985年   2篇
  1982年   1篇
  1973年   2篇
排序方式: 共有108条查询结果,搜索用时 15 毫秒
11.
12.
In this paper, the intra-seasonal variability of the abyssal currents in the China Ocean Mineral Resources Association (COMRA) polymetallic nodule contact area, located in the western part of the Clarion and Clipperton Fraction Zone in the tropical East Pacific, is investigated using direct observations from subsurface mooring instruments as well as sea-surface height data and reanalysis products. Mooring observations were conducted from September 13, 2017 to August 15, 2018 in the COMRA contact area (10°N, 154°W). The results were as follows: (1) At depths below 200 m, the kinetic energy of intra-seasonal variability (20?100 d) accounts for more than 40% of the overall low-frequency variability, while the ratio reaches more than 50% below 2 000 m. (2) At depths below 200 m, currents show a synchronous oscillation with a characteristic time scale of 30 d, lasting from October to the following January; the energy of the 30-d oscillation increases with depth until the layer of approximately 4 616 m, and the maximum velocity is approximately 10 cm/s. (3) The 30-d oscillation of deep currents is correlated with the tropical instability waves in the upper ocean.  相似文献   
13.
Using the Cut And Paste (CAP) method, we invert the focal mechanism of 38 moderate earthquakes (MS ≥ 3.0) recorded by Yunnan seismic network and analyze the corresponding focal mechanism consistency based on the minimum spatial rotation angle. Our results indicate that the MS 6.4 mainshock is induced by a lateral strike slip fault (with a rake angle of ~ ?165°) and a little normal-faulting component event along a nearly vertical plane (dipping angle~ 79° and strike ~138°). Combining our results with high resolution catalog, we argue that the seismogenic fault of this earthquake sequence is a secondary fault western to the major Weixi-Qiaohou-Weishan fault. The focal mechanism evolution can be divided into three periods. During the first period, the foreshock sequence, the focal mechanism consistency is the highest (KA<36°); during the second period which is shortly after the mainshock, the focal mechanism shows strong variation with KA ranging from 8° to 110°; during the third period, the seismicity becomes weak and the focal mechanism of the earthquakes becomes more consistent than the second period (18°<KA<73°). We suggest that the KA, to some extent, represents the coherence between local tectonic stress regime and the stress state of each individual earthquake. Furthermore, high focal mechanism consistency and high linearity of seismic distribution may serve as indicators for the identification of foreshock sequence.  相似文献   
14.
The physical processes of the feedback mechanism of direct shortwave radiative forcing of the Asian dust aerosol on dust emission has been examined using simulated results with the coupled (with dust shortwave radiative forcing) and the non-coupled model (without dust shortwave radiative forcing) based on the MM5 model and the Asian Dust Aerosol Model on 19 March 2002. The results indicate that a significant dust emission reduction occurs in the high dust concentration (HDC) region of the dust source region whereas an enhanced dust emission appears in the downstream of the dust source region. It is found that Asian dust aerosols raised during the daytime by the strong surface wind cause negative shortwave radiative flux near the surface, which in turn reduces the sensible heat flux causing the cooling of the air, thereby enhancing stable stratification. The dynamic adjustment of the negative radiative flux of the dust induces a positive pressure anomaly over the HDC region and a negative pressure anomaly toward the synoptic low pressure center, resulting in a dipole shape of pressure anomaly field near the surface. The associated secondary circulation of this pressure anomaly together with the reduction of turbulent intensity due to the reduced sensible heat flux reduces the low-level wind speed thereby reducing dust emission in the upstream of the HDC region of the dust source region (Region I), while enhancing the low-level wind speed in the downstream region (Region II), which in turn enhances dust emission. This enhanced dust emission is smaller than the emission reduction in the upstream, resulting in overall dust emission reduction during the daytime.  相似文献   
15.
Near-inertial motions contribute most of the velocity shear in the upper ocean. In the Bay of Bengal (BoB), the annual-mean energy flux from the wind to near-inertial motions in the mixed layer in 2013 is dominated by tropical cyclone (TC) processes. However, due to the lack of long-term observations of velocity profiles, our knowledge about interior near-inertial waves (NIWs) as well as their shear features is limited. In this study, we quantified the contribution of NIWs to shear by integrating the wavenumber-frequency spectra estimated from velocity profiles in the upper layers (40?440 m) of the southern BoB from April 2013 to May 2014. It is shown that the annual-mean proportion of near-inertial shear out of the total is approximately 50%, and the high contribution is mainly due to the enhancement of the TC processes during which the near-inertial shear accounts for nearly 80% of the total. In the steady monsoon seasons, the near-inertial shear is dominant to or at least comparable with the subinertial shear. The contribution of NIWs to the total shear is lower during the summer monsoon than during the winter monsoon owing to more active mesoscale eddies and higher subinertial shear during the summer monsoon. The Doppler shifting of the M2 internal tide has little effect on the main results since the proportion of shear from the tidal motions is much lower than that from the near-inertial and subinertial motions.  相似文献   
16.
Theoretical and Applied Climatology - The results of the present study prove that snowfall occurred due to the polar low (PL) in the Korean Peninsula and six cases of snowfall exceeding a snow...  相似文献   
17.
通过分析墨江5.9级地震前预测意见和预测资料,认为云南地区M≥5.5地震平静异常突出,M≥5.0地震连续间隔时间达200天以上,通海2次5.0级地震震级偏小是震前地震活动异常的显著特征;通海地震的指示意义、前兆异常M≥5.7地震中期和M≥5.0地震短临综合预测指标是判断地震短期可能性的主要依据;1900年以来,通海50km范围内M≥5.0地震后云南地区发生M≥5.0地震优势对应关系和GNSS表征的区域面应变变化特征为地点判定提供了线索。墨江5.9级地震的预测经验及资料的论证丰富了对地震孕育复杂性的认识,为震例积累了新的资料。  相似文献   
18.
Pre-metamorphic leptocephali of Pisodonophis sangjuensis (n = 91, 10.4?90.2 mm in total length, TL) were collected in the East China Sea for the first time. Pre-metamorphic leptocephali of P. sangjuensis, which were identified using mitochondrial DNA cytochrome c oxidase subunit I gene (mtDNA COI), are characterized by various combinations of morphological characters: 8 moderate to pronounced gut loops with the kidney terminating on the 6-7th loops; and 8 subcutaneous pigment patches on the tail just ventral to the notochord. Pisodonophis sangjuensis leptocephali were more numerously collected offshore than inshore around Jeju Island. The smallest leptocephali (< 15.0 mm TL) were collected from the south far from Jeju Island, and the largest leptocephali (> 100.0 mm TL) were collected from around Jeju Island and the southern coast of Korea. Our findings indicate that P. sangjuensis spawns offshore south of Jeju Island that is an area associated with high water temperature, and then the hatched leptocephali are transported to Jeju Island or the southern coast of Korea by the Tsushima Warm Current.  相似文献   
19.
Waveform inversion in the Laplace domain   总被引:12,自引:0,他引:12  
  相似文献   
20.
云南个旧锡多金属矿田构造岩相成矿规律与西区找矿研究   总被引:1,自引:0,他引:1  
云南个旧超大型锡多金属矿田研究成果很多,但是西区找矿一直没有取得突破。本文以建造构造成矿综合研究为基本思路,综合前人的大量资料,重点为西区建立了新的构造岩相找矿模型。以中三叠统个旧组为沉积建造基础,晚白垩世发育花岗杂岩体建造。中生代晚期经历了大规模的岩浆热液成矿过程,成矿时代覆盖了70~90 Ma,集中在80 Ma左右,形成最主要的成矿岩相。通过矿田构造岩相成矿图的编制,发现成矿阶段处于挤压伸展构造转换体制,认为原始的个旧断裂两盘成矿是一致的,西区与东区的成矿模型是相同的。构造岩相的界面成为构造岩浆热液流体充填和交代蚀变两种主要矿床类型的有利空间。矿田构造地层岩浆即构造岩相成矿模型显示,由于个旧断裂垂直和水平方向多期次、规模性活动的改造,西区表现为高隆起、复杂错动的构造特点,因而成矿构造岩相具有残留性、复杂性、低位性等特征。依据上述研究成果,结合地物化信息,指出了西区找矿方向和有利区段。  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