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991.
应用流体包裹体研究内蒙古巴彦浩特盆地热演化史 总被引:7,自引:3,他引:7
通过巴彦浩特盆地石炭系流体包裹体的研究认为 ,不同时代的样品尤其是中晚期包裹体的均一温度与埋藏深度之间存在良好的线性关系。有机质生烃在纵向上可以划分为未熟、低成熟、成熟及高成熟 4个阶段 ,时代上自侏罗系、下至奥陶系 ,跨度较大 ,却经历了相同的地热温度场。本区地温梯度较低 ,仅为 2 8~ 30℃ /km ,所有的升温热事件都发生在中侏罗世以后 ,主要勘探目的层石炭系烃源岩的成熟度处于液态窗阶段 ,有机质成熟、开始生烃的上限时间是侏罗纪以后 ,因此勘探目标应该以寻找晚期成藏为主 相似文献
992.
Based on mineralogical themometry and baroraetry and computation of mineral reactions modelling metamorphic sequence, a geotherm for metamorphic belts of the subduction zones has been deduced. Relatively low PT-values (3 kbar/200° C) correspond to zeolite and prehnite-pumpellyite metasediments and at higher pressures and temperatures (10 kbar/400 °C) lawsonite-glaucophane assemblages become unstable. The PT-curve achieves maximum at 11 kbar and 470° C to drop down to normal geotherm (Perchuk 1977). High concentration of H2O in the metamorphic fluid has been revealed, the difference between Pf1 and
being less than 2 kbar. Consideration has also been given to specific thermodynamic regime of zeolite and prehnite-pumpellyite zones of the younger island arcs, where lawsoniteglaucophane zones are absent. Here the geotherm has been found to rise from 0.2kbar/120° C up to 4 kbar/350° C and
-regime similar to that of glaucophane schists formations. 相似文献
993.
V. I. Nefedov N. M. Zhavoronkov G. V. Machavariani Ya. V. Salyn V. A. Makeev V. I. Zelenov 《Physics and Chemistry of Minerals》1982,8(5):193-196
Depth profiling analysis of native gold samples using X-ray photoelectron spectroscopy (XPS) shows the surface layers of lode gold to be significantly enriched with silver to a depth of 0.02–0.04 microns and the surface layers of placer gold to be depleted of silver up to a depth of several microns. The change in the surface composition of gold samples taken from oxidation zones is of more complicated character. Model experiments suggest the surface segregation of silver in lode gold samples to be due to outward diffusion and oxidation of silver at the surface. In placer gold the depletion of silver is caused by leaching of the latter from the surface layers. 相似文献
994.
M.Ya. Rudkevich 《Tectonophysics》1976,36(1-3)
The area of the West Siberian platform is about 3.3 million km2, the average thickness of the Mesozoic—Cenozoic platform mantle of sediments is 3 km, and the volume of sedimentary infilling is 10 million km3. The formation of the platform took place during a major tectonic cycle which in turn is divided into tectonic-sedimentary cycles as follows: Triassic, early-Middle Jurassic, late Jurassic, Neocomian, Aptian—Cenomanian, Turonian—Maastrichtian, Paleocene—early Oligocene and Middle Oligocene—Middle Pliocene. During the Triassic period in the arctic part of the platform large depressions were formed and continued to subside to the end of the Cretaceous. During early—Middle Jurassic part of the Triassic postorogenic shield began to subside. The late Jurassic epoch is characterized by maximum transgression and low rate of uncompensated subsidence of the basin floor. In Neocomian and Aptian—Cenomanian time, differential subsidence is sharply intensified, its rate increasing from south to north in the direction of Triassic downwarp. Turonian—Maastrichtian time is distinguished by wide transgression and reduction of subsidence rate. In Paleocene—early Oligocene the extent of the sea decreased and took the form of a submeridional gulf, the axial line of which approached the Urals. In the middle of the Oligocene epoch the sea became freshened and divided into separate basins. Eastern and northern parts of the platform were subsequently involved in the uplift. In the Neogene the region of subsidence took the form of a sublatitudinal depression extending along the southern mountain-folded margin of the platform. 相似文献
995.
进口水流条件及河道周界特征的改变是促使分汊河道主支汊交替的两大主要因素,不同类型的汊道对两者敏感性存在差异,辨析不同汊道主支汊交替的主导因素是预测汊道演变的前提。以长江中游分汊河道为参考,通过调整进口水流动力轴线走向及两汊的长度比设置了30种概化方案,采用平面二维水沙数学模型探讨上述两种因素对主支汊交替的影响。结论表明:两汊长度比存在一个临界值,当汊长比低于此临界值时,进口主流动力轴线的偏移是影响主、支汊交替的主要动力因素;超过此临界值后,进口水流条件变化对汊道分流格局的影响将会明显减弱,影响主支汊交替的主导因子将转换为汊道间的阻力对比关系;通过概化计算得到此临界值约为1.5。 相似文献
996.
997.
Heating of the primaeval plasma prior to the epoch of recombination results in distortions in the Rayleigh-Jeans region of the microwave relic radiation spectrum (1–60 cm, or more exactly =2.5–7/8 cm). The present observational data allow limits to be set to such energy injection from which follow upper limits to (a) the amount of antimatter in the universe; (b) the parameters of primaeval turbulence; and (c) the adiabatic fluctuation spectrum for small masses (M<1011
M
).If the heating takes place prior to the epocht=101012/5 sec (and in particular at the annihilation of electron-positron pairs atT108–1010 K,t<300 sec), no observable distortions are expected in the relic radiation spectrum. Here =/crit is the dimensionless average density of matter in the universe.Translated from the Russian by D. F. Smith. 相似文献
998.
999.
1000.
阿尔金断裂带东南缘含油气盆地群的形成演化 总被引:16,自引:0,他引:16
沿阿尔金断裂带东南侧发育六个中、新生代的含油气盆地,盆地的边缘或盆地内部发育一系列的近东西走向、与阿尔金断裂锐角相交的断裂,该组断裂对盆地的隆坳格局和地层分布具有控制作用,盆地具有箕状结构或不对称结构特点。沿阿尔金断裂带方向,保罗系、白垩系、古近系、新近系的厚度和沉积特征在时空上呈有规律性变化,显示了阿尔金断裂带时、空活动的差异性。根据侏罗纪盆地在阿尔金断裂带两侧的展布特征和柴达木盆地西部发育的鼻状构造及其沉积演化特征,推断阿尔金断裂带中、新生代经历了多期不同方向的走滑运动。 相似文献