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81.
Analysis and modeling of the seasonal South China Sea temperature cycle using remote sensing 总被引:1,自引:0,他引:1
Daniel J. Twigt Erik D. De Goede Ernst J. O. Schrama Herman Gerritsen 《Ocean Dynamics》2007,57(4-5):467-484
The present paper describes the analysis and modeling of the South China Sea (SCS) temperature cycle on a seasonal scale.
It investigates the possibility to model this cycle in a consistent way while not taking into account tidal forcing and associated
tidal mixing and exchange. This is motivated by the possibility to significantly increase the model’s computational efficiency
when neglecting tides. The goal is to develop a flexible and efficient tool for seasonal scenario analysis and to generate
transport boundary forcing for local models. Given the significant spatial extent of the SCS basin and the focus on seasonal
time scales, synoptic remote sensing is an ideal tool in this analysis. Remote sensing is used to assess the seasonal temperature
cycle to identify the relevant driving forces and is a valuable source of input data for modeling. Model simulations are performed
using a three-dimensional baroclinic-reduced depth model, driven by monthly mean sea surface anomaly boundary forcing, monthly
mean lateral temperature, and salinity forcing obtained from the World Ocean Atlas 2001 climatology, six hourly meteorological
forcing from the European Center for Medium range Weather Forecasting ERA-40 dataset, and remotely sensed sea surface temperature
(SST) data. A sensitivity analysis of model forcing and coefficients is performed. The model results are quantitatively assessed
against climatological temperature profiles using a goodness-of-fit norm. In the deep regions, the model results are in good
agreement with this validation data. In the shallow regions, discrepancies are found. To improve the agreement there, we apply
a SST nudging method at the free water surface. This considerably improves the model’s vertical temperature representation
in the shallow regions. Based on the model validation against climatological in situ and SST data, we conclude that the seasonal
temperature cycle for the deep SCS basin can be represented to a good degree. For shallow regions, the absence of tidal mixing
and exchange has a clear impact on the model’s temperature representation. This effect on the large-scale temperature cycle
can be compensated to a good degree by SST nudging for diagnostic applications. 相似文献
82.
为了改进肿瘤的微波热疗,我们进行915MHz微波亚铁磁共振的实验研究。结果表明915MHz微波象2450MHz一样,有明显而尖锐的亚铁共振升温。实验测量了不同聚集状态,不同饱和磁化强度亚铁磁共振介质的共振升温并用鸡蛋清受热固化来显示共振升温度分布的影响。 相似文献
83.
84.
Ruchi Mishra 《Planetary and Space Science》2006,54(2):188-199
Dispersion relation, resonant energy transferred, growth rate and marginal instability criteria for the electrostatic ion-cyclotron wave with general loss-cone distribution in low-β anisotropic, homogeneous plasma in the auroral acceleration region are discussed by investigating the trajectories of the charged particles. Effects of the parallel electric field, ion beam velocity, steepness of the loss-cone distribution and temperature anisotropy on resonant energy transferred and growth rate of the instability are discussed. It is found that the effect of the parallel electric field is to stabilize the wave and enhance the transverse acceleration of ions whereas the effect of steepness of loss-cone, ion beam velocity and the temperature anisotropy is to enhance the growth rate and decrease the transverse acceleration of ions. The steepness of the loss-cone also introduces a peak in the growth rate which shifts towards the lower side of the perpendicular wave number with the increasing steepness of the loss-cone. 相似文献
85.
86.
87.
亚洲中部干旱半干旱区近100年来的气温变化研究 总被引:5,自引:3,他引:5
利用亚洲中部干旱半干旱区1961—2003年共计69个站的气温实测资料,并通过EOF展开的延长插补方法,将研究区的气温序列延长到1901年,进而分析了这一区域近100年来的气温变化。研究表明,该区域气温的一致性变化占主导地位,同时存在东部季风区、中亚、蒙古高原和塔里木干旱区等4个主要温度变化分区,均表现出显著的增暖趋势,其代表站近100年来线性拟合的增温率分别为0.19,0.16,0.23和0.15℃/10a,研究区平均增温率为0.18℃/10a,冬季达0.21℃/10a,远高于北半球、全球和我国的增温率,但与青藏高原增温率相近。除20世纪10年代和50年代外,研究区气温变化主要取决于冬季温度的变化。研究区近100年来的气温变化经历了70年代以前的相对缓慢升温和以后的显著升温过程,且增温率越来越大。亚洲中部干旱半干旱区的气温变化过程与我国东部地区显著不同,没有出现明显的20~40年代暖期,整个升温过程由6次明显的锯齿状的升温-降温变化过程(即20,40,60,80,90年代和本世纪初气温变化过程)构成,升温阶段持续时间较长,幅度较大,而降温阶段时间短,幅度小,但不论升温还是降温过程,其变化幅度均大于我国东部和全球平均。 相似文献
88.
利用1952~2001年的印度洋海表温度资料、NCEP/NCAR的高度场资料,采用小波分析、交叉谱分析等方法,讨论了印度洋海温偶极子指数与南亚高压东西振荡的关系。结果表明:印度洋偶极子指数与南亚高压存在明显的负相关,且春季印度洋偶极子指数对同年夏季南亚高压的东西振荡有一定指示作用。印度洋偶极子指数与南亚高压东伸指数均存在8 a左右显著时间尺度。两者在1.5~8 a的周期上存在密切联系,在3 a左右的周期上,印度洋偶极子指数变化超前于南亚高压东伸指数,说明印度洋海温异常是影响南亚高压东西振荡的重要因素之一。 相似文献
89.
90.
Boreal temperature variability inferred from maximum latewood density and tree-ring width data, Wrangell Mountain region, Alaska 总被引:3,自引:0,他引:3
Variations in both width and density of annual rings from a network of tree chronologies were used to develop high-resolution proxies to extend the climate record in the Wrangell Mountain region of Alaska. We developed a warm-season (July–September) temperature reconstruction that spans A.D. 1593–1992 based on the first eigenvector from principal component analysis of six maximum latewood density (MXD) chronologies. The climate/tree-growth model accounts for 51% of the temperature variance from 1958 to 1992 and shows cold in the late 1600s–early 1700s followed by a warmer period, cooling in the late 1700s–early 1800s, and warming in the 20th century. The 20th century is the warmest of the past four centuries. Several severely cold warm-seasons coincide with major volcanic eruptions. The first eigenvector from a ring-width (RW) network, based on nine chronologies from the Wrangell Mountain region (A.D. 1550–1970), is correlated positively with both reconstructed and recorded Northern Hemisphere temperatures. RW shows a temporal history similar to that of MXD by increased growth (warmer) and decreased growth (cooler) intervals and trends. After around 1970 the RW series show a decrease in growth, while station data show continued warming, which may be related to increasing moisture stress or other factors. Both the temperature history based on MXD and the growth trends from the RW series are consistent with well-dated glacier fluctuations in the Wrangell Mountains and some of the temperature variations also correspond to variations in solar activity. 相似文献