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991.
992.
含对流与蒸发表面的有限厚度材料的双曲型热传导分析 总被引:3,自引:0,他引:3
本文对于含有对流与蒸发表面的有限厚度材料,在遭受一脉冲表面热流作用时的双曲型热传导进行了分析,采用热势函数描述的双曲型热传导方程来描述该问题,并用有限差分法进行数值求解.同时,本文还就表面对流与蒸发对材料表面与内部瞬态温度变化的影响以及材料双曲型热传导对表面蒸发的影响进行了分析. 相似文献
993.
994.
Ba0.95Ce0.9Y0.1O3-α固体电解质的氧离子导电性 总被引:1,自引:0,他引:1
Ba0.95Ce0.9Y0.1O3-α solid electrolyte was prepared by high temperature solid state reaction. The electrochemical oxygen permeation (oxygen pumping) rates and oxide ion transport number in this electrolyte were detected in the temperature of 600~1000℃ . It was found that this electrolyte exhibited the oxide ion conduction with the oxide ion transport number of 0.3~0.5. 相似文献
995.
In the current work, transient heat conduction in a semi-infinite medium is considered for its many applications in various heat fields. Here, the homotopy analysis method (HAM) is applied to solve this problem and analytical results are compared with those of the exact and integral methods results. The results show that the HAM can give much better approximations than the other approximate methods: Changes in heat fluxes and profiles of temperature are obtained at different times and positions for copper, iron and aluminum. 相似文献
996.
本文主要采用超声喷镀法在玻璃衬底上制备了N-Al共掺的p型ZnO薄膜.研究了前驱溶液的不同配比对薄膜电学、结构特性的影响.X射线衍射的结果显示:共掺与本征ZnO具有很相似的结晶特性.霍耳测试结果表明:随着Al原子掺入量的逐渐增加,制备ZnO的类型逐渐由n型转换成p型,进一步提高后又转换成n型,文中对其中的原因进行了讨论.在普通玻璃衬底上制备出了空穴浓度达到4.6×1018cm-3,同时迁移率和电阻率分别为0.4cm2·V-1·s -1、3.3Ω·cm的p型ZnO薄膜. 相似文献
997.
N. Tigau 《Crystal Research and Technology》2006,41(11):1106-1111
Antimony trioxide (Sb2O3) thin films have been deposited onto glass substrates using thermal evaporation technique at room temperature. The structural feature and surface morphology were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Sandwich‐type structures were deposited with films thickness d = 0.55 μm using evaporated electrodes of silver. Current‐voltage (J‐U) characteristics have been measured at various fixed temperatures in the range 293‐473 K. In all cases, at low electric field (E <104 V/cm), ohmic behavior is observed. However, at high electric field (E >104 V/cm), non‐ohmic behavior is observed. An analysis of the experimental data indicates that in the range of high‐applied electric field, the dominant conduction mechanism is space charge limited currents (SCLC). Using the relevant SCLC theory, the carrier concentration, total trap concentration and the ratio of free charge to trapped charge have been calculated and correlated with changes in the structures of antimony trioxide thin films. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
998.
The inverse heat conduction problem (IHCP) is a severely ill-posed problem in the sense that the solution ( if it exists) does not depend continuously on the data. But now the results on inverse heat conduction problem are mainly devoted to the standard inverse heat conduction problem. Some optimal error bounds in a Sobolev space of regularized approximation solutions for a sideways parabolic equation, i. e. , a non-standard inverse heat conduction problem with convection term which appears in some applied subject are given. 相似文献
999.
1000.
In systems of coupled transport processes the question of the appropriate driving potentials is a point of discussion. In
this article, three different approaches to derive models for transport currents are systematically compared. According to
a general linear approach, an arbitrary full set of independent state variables and material properties is sufficient to describe
any transport current. This approach is derived here from a symmetry principle. Thermodynamic and micromechanical approaches
are more complex and even less general, but they allow additional statements about the transport coefficients and they reduce
the number of transport processes. In the thermodynamic approach the additional information stems from the calculation of
the entropy production rate; the micromechanical approach involves a microphysical model of the considered porous system.
As a practical example, the three derivation schemes are applied to the often-encountered case of non-hysteretic heat and
moisture transport in homogeneous building materials. It is shown, how the general state variables of a porous system are
reduced to only two. Then from the general linear approach it can be seen, that all equations for the moisture transport current
using a main driving potential (e.g. moisture content, vapour pressure, chemical potential) and an independent secondary driving
potential (e.g. temperature, liquid pressure) are equivalent, without recurrence to the thermodynamic or micromechanical approach.
However, the transport coefficients are arbitrary phenomenological functions depending on the two state variables. Based on
a literature survey it is shown, which additional statements can be made in the thermodynamic and in the micromechanical approach.
The latter yields the pressure-driven model (vapour and liquid pressure as the two driving potentials). Finally it is shown,
what is to be expected, if in more complex systems the number of state variables increases. 相似文献