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101.
本文使用傅里叶变换微波谱仪研究了乙基苯胺类物质(邻乙基苯胺,间乙基苯胺,对乙基苯胺)的分子结构. 由于此类分子含氮原子(I14N=1),因此跃迁谱线中都呈现出核四级裂分. 通过比较实验测定得到的分子结构,可总结苯胺环上不同位置乙基的取代对氨基及分子整体结构的影响. 相似文献
102.
Synthesis and characterisation of the SrxBa1−xFeO3−y-system and the fluorinated phases SrxBa1−xFeO2F
Oliver Clemens Robert Haberkorn Peter R. Slater Horst Philipp Beck 《Solid State Sciences》2010,12(8):1455-1463
Compounds in the system SrxBa1?xFeO3?y have been prepared under different partial pressures of oxygen. In this system, different perovskite-type structures are found depending highly on the values of x and y. Fluorination using polyvinylidenedifluoride (PVDF) gives oxyfluoride materials of composition SrxBa1?xFeO2F, which normally crystallize in the cubic perovskite structure. Rietveld refinement results provide information about the packing density for oxide and oxyfluoride samples and allow a general comparison between these two different types of materials. Furthermore, the determination of the average iron oxidation state also showed that the oxygen deficiency, y, depends significantly on the value of x and the structure determined by the Sr/Ba ratio. 相似文献
103.
104.
105.
Metamer density estimated color correction 总被引:1,自引:0,他引:1
Color correction is the transformation of response values of scanners or digital cameras into a device- independent color
space. In general, the transformation is not unique due to different acquisition and viewing illuminants and non-satisfaction
of the Luther–Ives condition by a majority of devices. In this paper we propose a method that approximates the optimal color
correction in the sense of a minimal mean error. The method is based on a representative set of reflectance spectra that is
used to calculate a special basic collection of device metameric blacks and an appropriate fundamental metamer for each sensor
response. Combining the fundamental metamer and the basic collection results in a set of reflectances that follows the density
distribution of metameric reflectances if calculated by Bayesian inference. Transforming only positive and bounded spectra
of the set into an observer’s perceptually uniform color space results in a point cloud that follows the density distribution
of device metamers within the metamer mismatch space of acqcuisition system and human observer. The mean value of this set
is selected for color correction, since this is the point with a minimal mean color distance to all other points in the cloud.
We present the results of various simulation experiments considering different acquisition and viewing illuminants, sensor
types, noise levels, and existing methods for comparison. 相似文献
106.
We improve a recent result of Mauduit and Sárk?zy (2000) on the well-distribution measure of pseudorandom sequences and complement
another of their results on the correlation measure. 相似文献
107.
The binary hypercube Q
n
has a small diameter, but a relatively large number of links. Because of this, efforts have been made to determine the maximum
number of links that can be deleted without increasing the diameter. However, the resulting networks are not vertex‐symmetric.
We propose a family of vertex‐symmetric spanning subnetworks of Q
n
, whose diameter differs from that of Q
n
by only a small constant factor. When n=2k, the cube‐connected cycles network of dimension n is a vertex‐symmetric spanning subnetwork of Q
n+lg n
. By selectively adding hypercube links, we obtain a degree 6 vertex‐symmetric network with diameter 3n/2. We also introduce a vertex‐symmetric spanning subnetwork of Q
n−1 with degree log2
n, diameter 3n/2−2, log2
n‐connectivity and maximal fault tolerance. This network hosts Q
n−1 with dilation 2(log2
n)−1.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
108.
We report on the temperature and electric field strength dependence of the conductivity of iodine-doped polyacetylene in the metallic regime. The experimental results are discussed in terms of Sheng model of fluctuation induced tunneling and characteristic dimensions of the tunneling zones between fibres are deduced from a fit between this theory and our experiments. 相似文献
109.
110.
A Rank Encoder: Adaptive Analog to Digital Conversion Exploiting Time Domain Spike Signal Processing
Philipp Häfliger Elin Jørgensen Aasebø 《Analog Integrated Circuits and Signal Processing》2004,40(1):39-51
An electronic circuit is presented that encodes an array of analog input signals into a digital number. The digital output is a rank order code that reflects the relative strength of the inputs, but is independent of the absolute input intensities. In that sense, the circuit performs an adaptive analog to digital conversion, adapting to the average intensity of the inputs (i.e. effectively normalizing) and adapting the quantization levels to the spread of the inputs. Thus, it can convey essential information with a minimal amount of output bits over a huge range of input signals.As a first processing step the analog inputs are projected into the time domain, i.e. into voltage spikes. The latency of those spikes encodes the strength of the input. This conversion enables the circuit to conduct further analog processing steps by asynchronous logic. 相似文献