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871.
陈昊  胡小荣 《岩土力学》2020,41(7):2380-2388
基于材料三剪强度准则和非饱和土力学特性,提出了非饱和土的单应力变量和双应力变量三剪强度准则,并对其做了特征分析。分析表明,通过改变准则中的主应力影响系数b,所提准则就可以对其他强度准则进行非线性近似表达。在π平面的极限线中,所提强度准则覆盖了由内边界的单剪强度准则到外边界的三剪统一强度准则之间的所有外凸区域。因此,其适用于各种复杂应力状态下的非饱和土体,也能反映非饱和土单轴抗拉抗压强度不等的特征。另外,还用其他文献的真三轴试验数据对所提准则做了试验验证,其中,非饱和黏土砂的真三轴试验值与中主应力影响系数b=0.6时的三剪强度准则预测值吻合较好,双应力变量下准则的预测值比单应力变量下的预测值更符合试验值;非饱和黄土真三轴试验值与中主应力影响系数b=0.2时的三剪强度准则预测值吻合较好,两种应力变量下的三剪强度准则预测值差别较小。  相似文献   
872.
Bangong-Nujiang Suture Zone (BNSZ) in central Tibet plays an important role in evaluating the formation and uplift mechanism of Tibetan Plateau. However, its Mesozoic tectonic evolution is ambiguous and intensely debated. In this study, Early Cretacesous adakites and sodium-rich arc rocks are identified in Western Qiangtang (WQ) and Northern Lhasa (NL) sub-terranes. Forty-four adakite samples from both WQ and NL have akin geochemical features, and are derived from partial melting of subducted oceanic crust with amphibole residual. Nineteen sodium-rich samples originated from a mixed source region between crustal sediment and enriched lithospheric mantle. These two parallel arc belts separated by the Bangong-Nujiang Suture Zone (BNSZ) represent the divergent double subduction of the Bangong-Nujiang Tethyan Ocean (BNTO). Combined with the previous studies, our new data suggest three significant magmatic flare-ups at ∼240–140 Ma, 135–105 Ma and 92–60 Ma in the WQ and BNSZ, and two at 135–105 Ma and 92–60 Ma in the NL. These asymmetrical magmatic activities indicate that the southern subduction may have commenced at about 135 Ma and experienced slab breakoff at the latest Early Cretaceous, and the northern subduction could trace back to L-Triassic (228 Ma) and experienced episodic low-angle subduction, slab rollback (190-140 Ma) and oceanic ridge subduction (135-100 Ma). The 100–92 Ma magmatic gap, 92–60 Ma magmatic flare-up and L-Cretaceous angular unconformities indicate that the double-sided subduction of the BNTO resulted in soft collision with oceanic lithosphere detachment.  相似文献   
873.
双差定位法在三峡库区地震定位中的应用   总被引:12,自引:5,他引:7  
基于三峡地震台网2003年5月19日至2005年8月的地震记录资料,用双差定位法对发生于三峡库区(30.5°~31.5°N、109.5°~111.5°E)的1676次地震进行了重新定位。重新定位后的地震最大偏移量为10.93km,最小为0.08km,平均偏移量为1.87km,平均震源深度为6.59km。  相似文献   
874.
Mobile offshore double-causeway pier system, a type of seashore unloading equipment, consists of two groups of multiple connected semi-submersible modules. This structure has wide application because most of the middle or mini type of vessels and ships can be moored to it. Based on the analysis of computational methods of multi-body motion response, a hydrodynamic model is set up and the three-dimensional potential theory in finite depth is adopted to calculate the three-dimensional motion response of this system. The double P-M spectrum is used to analyze the motion response in irregular waves. Different wave directions are specially taken into consideration, due to their various effects to the motion response. Furthermore, the calculated result is compared with that of the experiment, and it is proved that sway, heave, pitch and yaw motion are greatly constrained by mooring system. The comparison also indicates that the model can forecast the motion performance of the target, and that the calculated result can also be used as reference in connector and mooring system design.  相似文献   
875.
基于双耦合Duffing振子的随机相位正弦信号检测   总被引:2,自引:0,他引:2  
首先采用双耦合混沌振子阵列实现了随机相位微弱正弦信号的检测,在此基础上,提出了新的检测方法,即利用单个双耦合混沌振子,通过临界到混沌及周期状态的变化检测随机相位微弱正弦信号并大致估计信号相位范围。该方法比双耦合混沌振子阵列法简单,更易于实现。  相似文献   
876.
The grid-point atmospheric model of IAP LASG (GAMIL) was developed in and has been evaluated since early 2004. Although the model shows its ability in simulating the global climate, it suffers from some problems in simulating precipitation in the tropics. These biases seem to result mainly from the treatment of the subgrid scale convection, which is parameterized with Tiedtke's massflux scheme (or the Zhang-McFarlane scheme, as an option) in the model. In order to reduce the systematic biases, several modifications were made to the Tiedtke scheme used in GAMIL, including (1) an increase in lateral convective entrainment/detrainment rate for shallow convection, (2) inclusion of a relative humidity threshold for the triggering of deep convection, and (3) a reduced efficiency for the conversion of cloud water to rainwater in the convection scheme.
Two experiments, one with the original Tiedtke scheme used in GAMIL and the other with the modified scheme, were conducted to evaluate the performance of the modified scheme in this study. The results show that both the climatological mean state, such as precipitation, temperature and specific humidity, and interannual variability in the model simulation are improved with the use of this modified scheme. Results from several additional experiments show that the improvements in the model performance in different regions mainly result from either the introduction of the relative humidity threshold for triggering of the deep convection or the suppressed shallow convection due to enhanced lateral convective entrainment/detrainment rates.  相似文献   
877.
基于单点定位的伪距双差研究及程序实现   总被引:1,自引:0,他引:1  
提出了基于单点定位的伪距双差法,提高了基线解算的速度,实现了对CORS数据的解算及分析。  相似文献   
878.
根据孤岛油田污水的现状及污水处理面临的主要问题,提出了利用气浮和"双膜"法处理油田污水进行配聚再利用的工艺,通过现场试验分析研究了处理前后3种水的水质指标,对比了配制的聚合物溶液的初始黏度和稳定性,结果表明,采油污水经该工艺处理后完全可以替代清水配制聚合物母液,具有较好的经济及社会效益。  相似文献   
879.
普兰店元台逆冲推覆构造为典型双重逆冲构造,以上叠式扩展而成。在自南向北逆冲过程中,形成褶皱推覆体,滞后断层,撕裂断层,反冲断层,并进一步形成构造窗和飞来峰。推覆构造形成于 J2-J3,逆冲推覆后期,花岗闪长斑岩沿逆冲推覆构造就位,其所携带的成矿热液在有利部位富集成金矿。  相似文献   
880.
Bertrand's law that the plant can't live in lack of some indispensable element, appropriate amount of the element will make the plant thrive but excessive amount of it will make the plant poisoning and even die was obtained through the study on the biologic adaptability in laboratory for the indispensable element manganese by G. Bertrand. E. D. Weinberg developed Bertrand's law as that certain amount of manganese was appropriate for the growth of some bacteria but not for the form of bacteriophage.The double threshold contents of elements indispensable for the organisms and their physiological effects can be extended to different hydrogeochemical zones of hydrogeological unit. Some elements are lack in the hydrogeochemical zone, in which the elements leaching and transfer are very strong the biological physiological effect is negative to the elements content. However, in the elements enrichment area caused by leaching and concentrating by evaporation or environmental pollution, the biological physiological effects are positive to the element content. The elements content in other areas which are in between two above types is appropriate for the organisms.From the hydrogeochemical study in Liliu , Shanxi province we obtained that the rate of KBD, IDD and dental caries are resulted from deficiency of elements Se, I and F in water (soil), respectively, the rate of diseases above is inversely related with the element content, while in the zone with excessive fluorine caused by enrichment and leaching, the rate of endemic fluorosis is positive to the fluorine content.  相似文献   
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