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71.
Kagiyma Mitsuyasu Ogasawara Yasuo Goto Kazuo Kajiya Fumihiko 《IEEE transactions on bio-medical engineering》1985,(8):630-633
This communication considers a method for evaluating fluctuations in the integral type output of a linear time-invariant compartmental system with a Markovian transition process. First, we derived a mathematical formula to calculate variances and covariances of integral type. outputs, as with radioisotope data, when transition rates are known. Then, an estimate for the upper limits of variances and covariances, i.e., 1/2?initial dose, when the transition rates are not given beforehand, was introduced. 相似文献
72.
Photoconductivity gain (PG) and persistent photoconductivity (PPC) properties observed in diamond photodetector are theoretically explained by solving rate equations which describe capture and emission processes of photo-generated hole and electron through a boron acceptor and a hole trap in a diamond epilayer and a nitrogen donor in a diamond substrate. Formation of one-sided pn-junction between the epilayer and substrate and slow hole capture rate of acceptor and hole trap levels provide accumulation of photo-generated hole in the epilayer, which produces the PG larger than the ideal responsivity. The PPC current after turning off the deep ultraviolet light is interpreted as due to the slow hole capture rate of the acceptor and trap levels. 相似文献
73.
Several fracture forces for the evaluation of the forming limit are investigated. The influence of flange lubrication, blank shapes, blank materials and tool shapes on the fracture forces is examined. The increase in the critical fracture force (the ability to sustain deep-drawing forces) is required for the improvement in the deep-drawability of square cups. Constant fracture force and transitional fracture force are used as target values for the increase in the critical fracture force. Both the fracture forces are independent of the blank shapes, and influenced by the flange lubrication, the blank materials and the tool shapes. The deep-drawability of square cups is evaluated by means of the fracture forces. 相似文献
74.
Source-Field Relationships for Cardiac Generators on the Heart Surface Based on Their Transfer Coefficients 总被引:1,自引:0,他引:1
We consider three different types of equivalent sources over a closed surface enclosing all the electrical cardiac generators: the (in situ) potential, the (in situ) normal current density, and the (macroscopic) transmembrane potential on the heart surface. The last equivalent source, which behaves as a double layer, is derived from the bidomain (bisyncytia) model for anisotropic cardiac muscle. This model predicts that if ratios of intracellular to interstitial conductivity along all directions are equal, field potential can be calculated only using surface integrals. The volume integral arising from the tissue anisotropy of cardiac muscle vanishes in that case. For each type of source under study, we give the field potential in a bounded inhomogeneous volume conductor in the form of an integral equation. We also derive the conditions which the lead field (or the transfer coefficients) must satisfy. The in situ potential and normal current are related to the cardiac sources in a complex way, but their lead fields are independent of conductivity of heart muscle, whereas the transmembrane potential is directly involved as a source term, but the lead field depends on the anisotropy of the heart muscle. 相似文献
75.
76.
Hiroyuki Mishima Mituo Kakei Toshio Yasui Saori Miyamoto Yasuo Miake Takaaki Yanagisawa 《Frontiers of Materials Science in China》2008,2(2):179-181
The present study was aimed at examining the nature of apatite crystal in the tooth apparatus of a conodont fossil using transmission
electron microscopy (TEM), scanning electron microscopy (SEM), laser Raman microprobe spectrometry and electron-probe microanalysis
(EPMA). The hard tissue of the condont consisted of 2 layers and the organization varied with the size of the crystal. Higher
magnification showed that the crystals were observed in the lattice of (100) and the central dark lines were not present.
Ca, P, and F were detected in the crystal using EPMA. Our results indicate that the apatite crystal in conodont fossils is
not hydroxyapatite but fluorapatite. 相似文献
77.
Yasuo Cho Teruaki Kasahara Koichi Fukuda 《Journal of the American Ceramic Society》1999,82(7):1720-1724
Two-dimensional images of the distribution showing the temperature coefficient of the dielectric constant for two types of two-phase composite ceramics composed of TiO2 -Bi2 Ti4 O11 and BaTi4 O9 -BaPr2 Ti4 O12 were obtained using scanning photothermal dielectric microscopy. The images of the TiO2 -Bi2 Ti4 O11 ceramic showed that the TiO2 and Bi2 Ti4 O11 grains had negative and positive temperature coefficients, respectively, and that the macroscopic averaged temperature coefficient of the ceramic was relatively low because of the cancellation of the opposite signs of the coefficients. On the other hand, the images of the BaTi4 O9 -BaPr2 Ti4 O12 ceramic showed that the temperature coefficient of both grains had the same sign (negative), although their absolute values were quite different. 相似文献
78.
79.
80.
Yanbo Li Takero Tokizono Meiyong Liao Miao Zhong Yasuo Koide Ichiro Yamada Jean‐Jacques Delaunay 《Advanced functional materials》2010,20(22):3972-3978
An increasing number of applications using ultraviolet radiation have renewed interest in ultraviolet photodetector research. Particularly, solar‐blind photodetectors sensitive to only deep UV (<280 nm), have attracted growing attention because of their wide applicability. Among recent advances in UV detection, nanowire (NW)‐based photodetectors seem promising, however, none of the reported devices possesses the required attributes for practical solar‐blind photodetection, namely, an efficient fabrication process, a high solar light rejection ratio, a low photocurrent noise, and a fast response. Herein, the assembly of β‐Ga2O3 NWs into high‐performance solar‐blind photodetectors by use of an efficient bridging method is reported. The device is made in a single‐step chemical vapor deposition process and has a high 250‐to‐280‐nm rejection ratio (~2 × 103), low photocurrent fluctuation (<3%), and a fast decay time (<<20 ms). Further, variations in the synthesis parameters of the NWs induce drastic changes in the photoresponse properties, which suggest a possibility for tuning the performance of the photodetectors. The efficient fabrication method and high performance of the bridged β‐Ga2O3 NW photodetectors make them highly suitable for solar‐blind photodetection. 相似文献