全文获取类型
收费全文 | 288篇 |
免费 | 31篇 |
国内免费 | 58篇 |
专业分类
测绘学 | 12篇 |
大气科学 | 119篇 |
地球物理 | 63篇 |
地质学 | 107篇 |
海洋学 | 24篇 |
天文学 | 41篇 |
综合类 | 4篇 |
自然地理 | 7篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 14篇 |
2012年 | 14篇 |
2011年 | 17篇 |
2010年 | 17篇 |
2009年 | 15篇 |
2008年 | 21篇 |
2007年 | 15篇 |
2006年 | 15篇 |
2005年 | 8篇 |
2004年 | 14篇 |
2003年 | 8篇 |
2002年 | 16篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 11篇 |
1998年 | 5篇 |
1997年 | 11篇 |
1996年 | 7篇 |
1995年 | 16篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 3篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有377条查询结果,搜索用时 15 毫秒
31.
用三年冬半年15个月500毫巴逐日资料,计算写成谱函数形式的角动量涡动输送,研究其周期变化。输送总值(波数k=1—12的总和)盛行准两周的周期,逐年差别不大。k=3波输送值也盛行准两周周期,近于同输送总值同位相,而且负担了50%以上的输送总值。其他波数,k=2盛行26天左右周期,k=4盛行12天左右周期,但这些波的变化幅度比k=3波小得多。初步考察了准两周周期同寒潮的关系。 用解纬圈谱法,选例考察k=3波的槽脊走向和振幅,有同角动量输送准两周变化相应的变化。 最后采用功率谱和交叉谱的分析法,对1976—1977年角动量输送进行统计上处理,得到一些与定性分析相同的结果。 相似文献
32.
大气动力学方程组的定性理论及其应用 总被引:9,自引:2,他引:7
基于完整的湿大气动力学方程组,利用无穷维动力系统的新理论和新方法,系统讨论了强迫耗散的非线性大气系统的定性理论及其应用。将完整的强迫耗散非线性湿大气动力学方程组化为Hilbert空间中一个等价的算子方程,研究了算子的性质及其物理意义,在此基础上得到湿大气系统全局吸引子的存在性定理,揭示出系统向外源的非线性适应特征,并把结果推广到有地形动力作用和非定常外源强迫的情形。同时探讨了大气方程组惯性流形的存在,大气多平衡态产生的根源以及强迫、耗散和非线性对系统解的渐近行为的影响。在理论结果的基础上,提出强迫耗散的非线性动力系统中存在三类时间边界层、方程组简化准则、分解算法的算子约束原则以及支撑吸引子基底的少数自由度的构造方法,探讨了理论在非线性发展方程差分格式的设计和计算稳定性分析、多平衡态的数值分析、数值模式延伸预报的改进、短期气候预测以及一类中尺度系统分析与预测中的应用,指出描述长期过程动力学模式的必备条件,给出初值与模式相协调的合理解释。最后,对今后的研究方向作了展望。 相似文献
33.
Shili Yang Wenjie Dong Jieming Chou Jinming Feng Xiaodong Yan Zhigang Wei Wenping Yuan Yan Guo Yanli Tang Jiacong Hu 《大气科学进展》2015,32(12):1683-1688
Integrated assessment models and coupled earth system models both have their limitations in understanding the interactions between human activity and the physical earth system. In this paper,a new human–earth system model,BNUHESM1.0,constructed by combining the economic and climate damage components of the Dynamic Integrated Model of Climate Change and Economy to the BNU-ESM model,is introduced. The ability of BNU-HESM1.0 in simulating the global CO2 concentration and surface temperature is also evaluated. We find that,compared to observation,BNU-HESM1.0underestimates the global CO2 concentration and its rising trend during 1965–2005,due to the uncertainty in the economic components. However,the surface temperature simulated by BNU-HESM1.0 is much closer to observation,resulting from the overestimates of surface temperature by the original BNU-ESM model. The uncertainty of BNU-ESM falls within the range of present earth system uncertainty,so it is the economic and climate damage component of BNU-HESM1.0 that needs to be improved through further study. However,the main purpose of this paper is to introduce a new approach to investigate the complex relationship between human activity and the earth system. It is hoped that it will inspire further ideas that prove valuable in guiding human activities appropriate for a sustainable future climate. 相似文献
34.
Z. F. Gao Q. H. Peng N. Wang C. K. Chou W. S. Huo 《Astrophysics and Space Science》2011,336(2):427-439
As soon as the energies of electrons near the Fermi surface exceed Q, the threshold energy of inverse β-decay, electron capture (EC) dominates inside a neutron star. The high-energy neutrons released by EC will destroy anisotropic
3
P
2 neutron Cooper pairs in the degenerate superfluid. By colliding with the neutrons produced in the process n+(n↑n↓)→n+n+n, the kinetic energies of the neutrons released by EC will be transformed into thermal energy. A portion of this thermal energy
will be transported from the star interior to the star surface by conduction, then converted to a thermal spectrum of soft
X-rays and γ-rays. By introducing two important parameters: the Landau level-superfluid modified factor and the overal soft X/γ-ray efficiency coefficient, we compute the theoretical luminosity L
X
of a magnetar under our model and plot a diagram of L
X
as a function of magnetic field strength B. Numerical calculations based on our model agree well with the observed properties of magnetar candidates. 相似文献
35.
Hoshu Chou 《Frontiers of Earth Science》2010,4(1):83-88
Because of slender land and high mountain, steep slope, and rapids of natural environment, the whole regional ecosystem has
the changeable terrain and landscape with diverse ecology and species. During the past 300 years, the humanity lives and spreads
on this splendid domain, accomplished the complex, fragment and sensitive of nature and humanities ecosystem, and its Landscape
ecology texture. This paper finds out that, although the National Parks system in China has been in operation for over 30
years and has achieved the objective of species conservation, it is still facing the a conflicting situation and coordinated
demand of its conservation and recreation. With the global tendency of “sustainable development” and “ecotourism”, this paper
suggests that National Park system should establish a sustainable development mechanism integrating “conservation, recreation,
and research.” Therefore, this paper suggests shifting the traditional planning paradigm of resource benefit guidance and
resource valuation framework of Ecological Planning to the “Sustainable Planning” theory and technique that are suitable for
sustainable development concept in order to meet the demand for a new conservation concept and technique of sustainable development
for the human beings dealing with the environment resources. Also, the texture and model of Landscape ecology and the model
and method of Geographic Informational System could be considered as the proper tool. This paper points out that the landscape
ecology texture and tendency should represent the secret code of sustainable development. Furthermore, the situation of the
sustainable development is dynamic, and the GIS model is necessary for corresponding planning. Finally, this paper develops
a suitable sustainable development operation definition and planning methodology to represent the interlacing framework of
ecology (conservation) and human being (e.g., recreation, research, life, etc.) system of National Park management. 相似文献
36.
The effect of a strong magnetic field on neutron stars or white dwarfs is calculated for Thomson scattering in a strong magnetic field with radiation damping. The Stokes's parameters for the scattered radiation are computed explicitly in terms of the state of polarization of the incident wave, the electrocyclotron frequency, the angle of incidence, and the angle of scattering. The criterion for the magnetic field to substantially affect the Stokes's parameters is that the photon frequency be less than the electrocyclotron frequency. The effects of classical radiation damping are explicitly taken into account by using the Abraham-Lorentz equation. The corresponding quantum mechanical treatment for Compton scattering in a relativistic electron gas is now under investigation. 相似文献
37.
形变监测是海塘安全运行的重要组成部分。本文利用杭州地区2006年—2010年获取的31景EnvisatASAR影像,根据MTInSAR(Multi-Temporal In SAR)方法,综合提取PS(Persistent Scatterer)和DS(Distributed Scatterer)点,得到密集的钱塘江海塘形变的In SAR测量结果。与28个点的水准数据对比表明,两者的平均误差为0.436 mm,最大误差为5.016 mm,验证了In SAR技术毫米级的测量精度和准确性。通过这两种数据的时间序列分析发现,海塘的沉降在空间上具有连续性,其空间分布呈现为单峰下沉曲线;在时间上,则具有明显的线性变化规律,并伴随有短时间范围的小幅度波动。 相似文献
38.
Silvina A. Solman E. Sanchez P. Samuelsson R. P. da Rocha L. Li J. Marengo N. L. Pessacg A. R. C. Remedio S. C. Chou H. Berbery H. Le Treut M. de Castro D. Jacob 《Climate Dynamics》2013,41(5-6):1139-1157
The capability of a set of 7 coordinated regional climate model simulations performed in the framework of the CLARIS-LPB Project in reproducing the mean climate conditions over the South American continent has been evaluated. The model simulations were forced by the ERA-Interim reanalysis dataset for the period 1990–2008 on a grid resolution of 50 km, following the CORDEX protocol. The analysis was focused on evaluating the reliability of simulating mean precipitation and surface air temperature, which are the variables most commonly used for impact studies. Both the common features and the differences among individual models have been evaluated and compared against several observational datasets. In this study the ensemble bias and the degree of agreement among individual models have been quantified. The evaluation was focused on the seasonal means, the area-averaged annual cycles and the frequency distributions of monthly means over target sub-regions. Results show that the Regional Climate Model ensemble reproduces adequately well these features, with biases mostly within ±2 °C and ±20 % for temperature and precipitation, respectively. However, the multi-model ensemble depicts larger biases and larger uncertainty (as defined by the standard deviation of the models) over tropical regions compared with subtropical regions. Though some systematic biases were detected particularly over the La Plata Basin region, such as underestimation of rainfall during winter months and overestimation of temperature during summer months, every model shares a similar behavior and, consequently, the uncertainty in simulating current climate conditions is low. Every model is able to capture the variety in the shape of the frequency distribution for both temperature and precipitation along the South American continent. Differences among individual models and observations revealed the nature of individual model biases, showing either a shift in the distribution or an overestimation or underestimation of the range of variability. 相似文献
39.
Gross moist stability, an effective static stability, in the tropics is examined in observations and model simulations. Under convective quasi-equilibrium closure, gross moist stability, a vertical integration of the vertical moist static energy gradient weighted by pressure velocity, is derived based on an approximately moist adiabatic process associated with deep convection. In climatology, gross moist stability is generally similar to the spatial distribution of mean precipitation. In global warming simulations, gross moist stability tends to increase in the tropics. It implies a more stable atmosphere, which is consistent with the weakening of tropical circulation found in climate models. Main effects, which induce the changes in gross moist stability, include the low-level moisture effect, the maximum level of convection (MLC) effect, i.e., the depth of deep convection, and the dry static energy effect associated with stratification of temperature, with the first two also found in climatology. Because of the strong cancellation between the effects of low-level moisture and dry static energy due to the moist adiabatic process of deep convection, the effect of MLC, which has been overlooked in measuring atmospheric stability, is crucial in determining the sign of changes in gross moist stability. Gross moist stability is a better index to represent changes in atmospheric stability in the tropics under global warming, compared to both dry and moist static stability. 相似文献
40.
This study evaluates the convectively coupled equatorial waves in ten coupled general circulation models (GCMs) in the twentieth century experiment from the Coupled Model Intercomparison Project phase 3 of the World Climate Research Programme. The antisymmetric bands in all GCMs are weaker than in observations, and the mixed Rossby-gravity (MRG) wave seems to be a mixture of the equatorial Rossby (ER) and tropical depression-type (TD-type) waves rather than a mixture of the ER and inertiogravity waves found in observations. The simulated TD-type wave is more organized than in observations with a quasilinear wavenumber–frequency relationship. In most GCMs, the two observed activity centers of the MRG and TD-type waves over the southern Indian Ocean and the southwestern Pacific cannot be separated; only one wave activity center is found over the Maritime Continent. The observed northwestward propagation of the TD-type wave over the western North Pacific is also not well simulated in the GCMs. The simulated active season of the MRG and TD-type waves over the northern hemisphere during the boreal summer and fall is much shorter than in observations. The models from CCSR utilizing the Pan and Randall scheme with the convection suppression simulate the realistic Kelvin wave activity with the maximum activity near the equator, while the wave activities filtered for the Kelvin wave in the other GCMs are similar to the extratropical Rossby wave with the maximum activity at higher latitudes. Likewise, only these two models produce a realistic seasonal cycle of the Kelvin wave activity. 相似文献