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991.
Lionel Fabrice Houlet Woosuck Shin Maiko Nishibori Noriya Izu Toshio Itoh Ichiro Matsubara 《Applied Surface Science》2008,254(16):4999-5006
A study on the electrode contact of the sputtered SiGe thin film is reported for application of devices working at high temperature. Surface morphological characterization with optical microscope and AFM (atomic force microscope) together with the electrical characterization by TLM measurements (transmission line method) were performed before and after aging at 500 °C for 24 h using various sputtered multilayer electrodes, Ti/Au/Ti, Ta/Pt/Ta and Ti/Pt/Ti, on 300-nm B-doped SiGe thin film deposited by magnetron sputtering and furnace crystallisation at high temperature. After aging at 500 °C for 24 h, the Ti/Au/Ti multilayer electrodes seriously degraded to be non-ohmic contact, showing rough surface morphology. The Ti/Pt/Ti metal layers showed the lowest specific contact, resistivity before and after aging, 1.46 × 10−3 Ω cm2 and 1.68 × 102 Ω cm2 respectively. 相似文献
992.
The article gives an introduction into the application of density functional theory (DFT) to inhomogeneous systems. To begin with, we describe the interplay of specific materials at interfaces, resulting in structure relaxation and modifications of the chemical bonding. We address interfaces between YBa2Cu3O7 and a normal metal, in order to quantify the intrinsic interface charge transfer into the superconductor. Moreover, we study the internal interfaces in a V6O13 battery cathode and the effects of ion incorporation during the charging and discharging process. The second part of the article deals with the influence of surfaces on the nearby electronic states. Here, we investigate a LaAlO3/SrTiO3 heterostructure in a thin film geometry. We particularly explain the experimental dependence of the electronic states at the heterointerface on the surface layer thickness. Afterwards, surface relaxations are studied for both the clean Ge(001) surface and for self‐assembled Pt nanowires on Ge(001). In the third part, we turn to atomic and molecular contacts. We compare the properties of prototypical Al nanocontact geometries, aiming at insight into the chemical bonding and the occupation of the atomic orbitals. Finally, the local electronic structure of a benzene‐1,4‐dithiol molecule between two Au electrodes is discussed as an example for a molecular bridge. 相似文献
993.
In this study, the influence of the surface layer (p-InGaN or p-GaN) capping p-InGaN/p-GaN superlattices (SLs) on the contact to p-type GaN was investigated. It was found that the specific contact resistance (ρc) to p-type GaN is lower when using p-InGaN as the surface layer. The lowest value of ρc was 1.99×10−4 Ω cm2 at room temperature. It was also found that low temperature growth of the p-GaN layers in the SLs is beneficial for lowering the ohmic contact resistance. Unlike Ni/Au deposited directly on p-GaN (without the strained p-InGaN/p-GaN SLs), Ni/Au deposited on p-InGaN/p-GaN SLs produces ohmic behavior even before annealing. 相似文献
994.
B. V. Perepelitsa 《Thermophysics and Aeromechanics》2008,15(4):567-572
Results of experimental investigation of temperature distribution over the surface of a complex heat exchanger (the Frenkel
packing type) are presented. Measurements were carried out in the air flow between two sheets with triangular corrugations
directed at 90° to each other. Measurements were carried out by the microthermocouples glued on the heated outer surface.
The effect of Reynolds numbers, a gap between corrugated sheets, and substitution of one corrugated sheet by the smooth one
on temperature distribution over the heat exchanger surface in the turbulent air flow is analysed. According to the performed
experiments, there is a significant effect of a gap and applied perturbations on the type of temperature distribution over
the perimeter of a heated cell. 相似文献
995.
《Applied Surface Science》2008,254(10):3039-3044
In this work, we have investigated the electrical characteristics, such as current-voltage (I-V) and capacitance-voltage (C-V) measurements, of identically prepared crystal violet/p-Si Organic/Inorganic (OI) Schottky structures formed by evaporation of organic compound solution to directly p-Si semiconductor substrate. It has been seen that the crystal violet organic dye thin film on the p-Si substrate has exhibited a good rectifying behavior. The barrier heights (BHs) and ideality factors of all devices have been calculated from the electrical characteristics. Although the diodes were all identically prepared, there was a diode-to-diode variation: the effective barrier heights ranged from 0.6 ± 0.1 to 0.8 ± 0.1 eV, and the ideality factor from 1.6 ± 0.4 to 3.5 ± 0.4. The barrier height versus ideality factor plot has been plotted for the OI devices. Lateral homogeneous BH was calculated as a value of 0.7 eV from the observed linear correlation between BH and ideality factor, which can be explained by laterally inhomogeneities of BHs. The values of barrier height and acceptor doping concentration yielded from the reverse bias C-V measurements ranged from 0.7 ± 0.1 to 1.3 ± 0.1 eV and from (4.7 ± 0.8) × 1014 to (8.1 ± 0.8) × 1014 cm−3, respectively. The mean barrier height and mean acceptor doping concentration from C-V characteristics has been calculated 1.0 eV and 5.9 × 1014 cm−3, respectively. It has been seen that the mean BH value of 0.7 eV obtained for the Al/methyl violet/p-Si contact is significantly larger than BH values of the conventional Al/p-Si Schottky diodes. Thus, modification of the interfacial potential barrier for metal/Si diodes has been achieved using a thin interlayer of the methyl violet organic semiconductor; this has been ascribed to the fact that the methyl violet interlayer increases the effective barrier height by influencing the space charge region of Si. 相似文献
996.
Proteins are important biomolecules, which perform diverse structural and functional roles in living systems. Starting from
a linear chain of amino acids, proteins fold to different secondary structures, which then fold through short- and long-range
interactions to give rise to the final three-dimensional shapes useful to carry out the biophysical and biochemical functions.
Proteins are defined as having a common ‘fold’ if they have major secondary structural elements with same topological connections.
It is known that folding mechanisms are largely determined by a protein’s topology rather than its interatomic interactions.
The native state protein structures can, thus, be modelled, using a graph-theoretical approach, as coarse-grained networks
of amino acid residues as ‘nodes’ and the inter-residue interactions/contacts as ‘links’. Using the network representation
of protein structures and their 2D contact maps, we have identified the conserved contact patterns (groups of contacts) representing
two typical folds — the EF-hand and the ubiquitin-like folds. Our results suggest that this direct and computationally simple
methodology can be used to infer about the presence of specific folds from the protein’s contact map alone.
相似文献
997.
粉末热压扩散与应力场耦合的力学模型 总被引:3,自引:0,他引:3
以弹性接触应力场为初始条件,建立了热压条件下球形颗粒表面扩散与应力场耦合的力学模型. 引入包含表面能项级数形式的应力函数,以描述随时间演化的表面扩散过程及扩散对应力场演化的影响. 而应力场通过改变化学势梯度,又会促进(或阻止)表面扩散结合的进程.利用该模型分析了压力、温度和界面区应力场演化对致密化参数的影响. 比较了满足粘着或非粘着对结合宽度和应力分布的影响,将考虑粘着的弹性接触应力场作为初始条件,分析了弹性变形和表面扩散共同驱动的粉末冶金热压烧结致密化规律. 相似文献
998.
Elaine Pratt Alain Leger Michel Jean 《Archive of Applied Mechanics (Ingenieur Archiv)》2008,78(2):89-104
Critical values of the parameters governing the dynamics of simple systems appear when Coulomb friction is not regularized.
We explore such systems using a method based on the fact that under constant or analytical data the trajectory exists, is
unique and is also sufficiently regular. In fact these properties justify elementary analytical computations on successive
time intervals where the condition used to connect the solution from one interval to the other is due to the regularity. Although
the systems are simple the dynamics turn out to be quite complex and thus furnish an interesting benchmark for contact dynamics
numerical codes. Among other possible applications we choose to present here how to use a mass–spring chain with Coulomb friction
to slow down in a progressive and regular manner an oncoming mass with a given initial velocity. 相似文献
999.
1000.