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ASTER多光谱遥感数据目前可以用于岩石矿物资源信息的识别和提取。本研究尝试利用ASTER 可见光近红外(VNIR)和短波红外(SWIR)的多光谱遥感数据提取干旱地区的岩石与矿物信息。基于新疆天山西南缘柯坪隆起东部不同地层单元岩石的化学组成和矿物成份以及VNIR SWIR谱域光谱吸收特征的分析,我们采用相关吸收波段深度(RBD)和波段比值(BR)方法对研究区的多光谱遥感数据进行图像处理,有效区分和识别了白云岩、石灰岩、砂岩以及阿克苏群的蓝片岩—绿片岩和砂质片岩。白云岩的CO2-3吸收谱带中心波长位于232〖KG*3〗μm,与灰岩的CO2-3 吸收谱带中心波长位置235 μm相比,具有向短波长方向移动的特点,据此可以利用RBD7、RBD8分别有效的识别白云岩和灰岩; 长英质岩石显示Al OH和Fe3+ VNIR SWIR吸收特征,而基性 超基性岩石显示Fe2+ 和Fe、Mg OH特征,利用不同的铁价态和次要矿物可以区分它们:ASTER band2/band1代表了含Fe3+ 矿物分布信息、ASTER band5/band4代表了含Fe2+ 矿物分布信息、RBD6可以估计Al OH矿物的丰度; 砂质/泥质片岩含较多的多硅白云母、绿泥石、黑硬绿泥石以及风化后表面覆盖的其它粘土矿物,在221 μm(band 6)存在有特征的吸收谱带,并且在165 μm(band 4)具有较高的反射率,而蓝片/绿片岩在221 μm(band 6)反射率较高,不具有明显特征吸收谱带,同时其在165 μm(band 4)反射率较低,因此蓝片/绿片岩ASTER band4/band6 比值低。应用ASTER band4/band6波段比值可以有效的区分开砂质/泥质片岩与蓝片岩/绿片岩。 相似文献
114.
Wave tank tests were carried out to evaluate the total efficiency of a floating OWC Pentagonal Backward Bent Duct Buoy (PBBDB). Two kinds of turbine generators were used in tests. The incident wave power, pneumatic power and electricity were measured. The test results show that the primary efficiency can reach up to 185.98% in regular waves and 85.86% in irregular waves. The total efficiency from wave to wire with Wells turbine-generator set is 33.43% in regular waves and 15.82% in irregular waves. The peak total efficiency of the PBBDB with check valves equipped with the impulse turbine-generator set is 41.68% in regular waves and 27.10% in irregular waves. The efficiency of the turbine-generator set is about 30% in the tests. Obviously, the total efficiency can be further improved with the increasing of turbine efficiency. 相似文献
115.
Fausto T. GrattonCharles J. Farrugia Laurence Bender 《Planetary and Space Science》2003,51(12):769-783
A MHD theory of combined Kelvin-Helmholtz (KH) and Rayleigh-Taylor (RT) instabilities for a transition layer with two different scale lengths (Δ and δ for the variation of velocity/magnetic fields and density, respectively) is presented. The study is motivated by reports of magnetopauses with no low latitude boundary layer, in which a sharp density drop over a distance δ?Δ is observed (“pristine” magnetopauses (J. Geophys. Res. 101 (1996) 49). The theory ignores compressibility effects and applies to subsonic regions of the dayside magnetopause. The RT effect is included to account for temporary periods of acceleration of the magnetopause, caused by sudden changes of the solar wind dynamic pressure. For small wavelengths λ, such that δ?λ?Δ, a WKB solution shows that the velocity gradient operates, together with magnetic tensions, to attenuate or even stabilize the Rayleigh-Taylor instability within a certain wavelength range. An exact dispersion relation for flute modes, valid for all λ, in the form of a fourth order polynomial for the complex frequency ω, is obtained from a model with a constant velocity gradient, dV/dy within Δ, and with δ→0. Flute modes are possible because of the existence of bands of very small magnetic shear on the dayside magnetopause (J. Geophys. Res. 103 (1998) 6703). The exact solution allows for a study of the change of the action of the velocity gradient with λ from the long-λ range where dV/dy is KH destabilizing to the short-λ range where dV/dy produces a stabilizing effect. Both, the WKB approximation and the well known tangential discontinuity model (Δ→0) are recovered as limiting cases of the exact solution. Properties of the KH and RT instabilities, for different density ratios on either side of the magnetopause, are described. For flute modes, at very small λ the RT instability grows faster and becomes the dominant effect. However, it is shown that the growth rate remains bounded at a finite value as λ→0, when a theory with a finite δ model is considered. To study configurations with finite, arbitrary, δ/Δ ratios, the MHD perturbation equations are solved numerically, using hyperbolic tangent functions for both the density and velocity transitions across the magnetopause. To examine the influence of different δ/Δ ratios on the growth rates of KH and RT, calculations are performed for different δ/Δ, with and without acceleration, and for two different density ratios. It is found that the general features exhibited by the constant dV/dy model, are confirmed by these numerical solutions. The stability of pristine magnetopauses, and the possibility of observing some theoretical predictions during magnetopause crossings in ongoing missions, are discussed. 相似文献
116.
C. L. Jin Z. Q. Qu C. L. Xu X. Y. Zhang M. G. Sun 《Astrophysics and Space Science》2006,306(1-2):23-27
Stokes profile inversion is very important to get the information on the vector magnetic field. Because the magnetic fields cannot be directly observed, adopting Stokes spectrum analysis to obtain vector magnetic field has become the major technique recently. Therefore, by Stokes profile inversion, we obtained vector magnetic fields of two layers based on the numerical solution (DELO solution, ReEs et al., 1989) to the polarized radiative transfer equation. We analyze the relationships of sunspot magnetic field strength with sunspot area, umbral area and penumbra-umbra radius ratio. By statistical research, it is found that the field strengths of the upper layer and the lower one decrease with the increasing penumbra-umbra radius ratio, and that the logarithmic expression is able to fit well the relationship between the maximum field strength of the upper layer and the sunspot area. Furthermore, we verify the result obtained by Ringnes and Jensen (1961) about the relationship between the maximum magnetic field strength and the umbral area, and the result obtained by Antalová (1991) of the relationship between the field strength and the penumbra-umbra radius ratio. 相似文献
117.
李自新 《广东海洋大学学报》1994,(2)
传动比方案设计是行星变速箱CAD技术中的关键问题之一。本文应用行星变速箱基本设计理论和计算机技术,建立了行星变速箱传动比方案CAD软件,为有关科研部门及生产企业的产品开发提供了一种有效手段。 相似文献
118.
以实际沉积地层中抽象出来的砂泥岩地层概念模型为研究对象, 在盆地构造力学、岩石力学性质分析的基础上, 采用应力场数值模拟法研究分析砂泥岩地层中的纵向地应力分布特征和规律。研究结果表明, 水平主应力在砂泥岩的分界面发生突变, 变化程度主要与两侧岩石的力学性质差异相关, 也与区域构造应力有一定关联; 杨氏模量对最大水平主应力影响程度大于对最小水平主应力的影响, 泊松比对地层最小水平主应力影响程度大于对最大水平主应力的影响。杨氏模量和泊松比对最大水平主应力的影响, 在伸展应力状态下前者影响相对较小, 走滑应力状态下, 影响程度基本相同, 挤压应力状态下, 前者影响程度相对较大; 而对于最小水平主应力的影响, 在三种应力状态下, 泊松比的影响均大于杨氏模量。地层的岩性变化方式(渐变或突变)对地层最小水平应力差产生显著影响, 厚度变化对地层最小水平应力差大小无影响。上述认识可以指导砂泥岩地层的压裂和储层改造, 改善压裂效果。 相似文献
119.
土壤水分及土壤-大气界面对麦田水热传输的作用 总被引:11,自引:2,他引:11
文章根据1996年在中国栾城农业生态试验站观测的田间试验资料,分析了土壤水分和土壤-大气界面对麦田水热传输的抑制和加速作用。对于显热和潜热输送,土壤水分起决定作用,土壤水分越小,显热通量越大,潜热通量越小,反之亦然。只在土壤水分较小时界面厚度对显热和潜热输送作用较大。对于土壤热输送,界面厚度起决定作用,界面厚度越大土壤热通量越小。分析还发现60cm深处土壤水势与叶水势和大气水势的相关系数较其它深度处的土壤水势大。0~60cm土层是确定土壤水分运动对界面水热传输影响的一个良好的指示层。 相似文献
120.