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91.
92.
93.
D. X. Xu G. D. Shen M. Willander J. Knall M. -A. Hasan G. V. Hansson 《Journal of Electronic Materials》1990,19(10):1033-1041
Different Si homojunction and strained Si1-xGex/Si heterojunction diodes and bipolar transistors have been fabricated by Si-MBE. The effect of annealing on Si homojunction
diodes and transistors are studied. It is found that annealing generally improves the Si device performance, such as the ideality
factor and breakdown characteristics. The influence of60Co γ irradiation on the Si1-xGex/Si diode performances are investigated by studying the temperature dependence of their electrical characteristics, and the
results are correlated with the quality of the MBE-films. γ irradiation causes a drop in material conductivity due to the
generation of atom-displacement defects in the whole volume of the wafers and increases the defect density at hetero-interfaces.
The forward I-V curves of Si1-xGex/Si devices may shift towards lower or higher voltages, depending on the film quality and the irradiation dose. The increase
of defect density in strained Si1-xGex/Si films appears to occur easier for the films with lower quality. Electrical measurements and calculations show that the
defect-associated tunneling process is important in current transport for these MBE grown Si homojunction and strained Si1-xGex/Si heterojunction devices, which have initially medium film quality or have been treated by irradiation. 相似文献
94.
传统的航空激光增材制造零部件潜在缺陷检测方法检测准确度低,图像特征查全率低。基于上述问题,提出一种基于图像识别技术的航空激光增材制造零部件潜在缺陷检测方法。采用红外成像技术进行航空激光增材制造零部件成像处理,提取航空激光增材制造零部件红外图像的缺陷区域特征点,对红外图像进行中值滤波降噪处理,利用扫描图像的纹理异常分布特性进行潜在缺陷的自适应定位检测,结合模板匹配和角点检测方法,实现对航空激光增材制造零部件潜在缺陷检测。仿真结果表明,采用该方法方法的图像特征提取查全率比传统方法提高了15%~20%,能够清晰检测到增材零件的潜在缺陷。说明进行航空激光增材制造零部件潜在缺陷检测的准确性较好,对缺陷部位定位的误差较小。 相似文献
95.
In nearly all cases when an epitaxial layer of HgCdTe is grown on a CdZnTe substrate, there will be a finite lattice mismatch
due to the lack of precise control over the ZnTe mole fraction. This leads to strains in the layer, which can be manifested
in one or more ways: (1) as misfit dislocations near the interface, (2) as threading dislocations, (3) as surface topographical
textures, and (4) as cross-hatch lines seen by x-ray topography. We have found that much of the strain can be relieved by
growing on a reticulated substrate. Specifically, when the substrate has been etched to form mesas prior to growth of the
layer, the resulting layer on the tops of the mesas shows evidence of significantly reduced strain. CdZnTe substrates oriented
(111)A were prepared with two sets of mesas on 125 μm centers and 60 μm centers, and with other planar areas remaining for
comparison. From a Hg melt, a layer of LWIR HgCdTe was grown about 16 μm thick on each substrate. Nomarski microscopy showed
that the layers on the mesa tops were extremely flat, showing no sign of curvature or surface texture. X-ray topography showed
no cross hatch on the mesa tops, while the usual cross hatch appeared in the planar regions. The LPE layer extended laterally
beyond the edges of the original mesa because of faster growth in non-(111) directions. Samples were cleaved and examined
in cross section. The linear density of etch pits seen in the cross section near the substrate, which represent misfit dislocations,
was three times lower in the layer on the mesas than in the layer in the unpatterned region, although both regions have the
same layer/substrate lattice mismatch. When an epilayer is grown on an unpatterned wafer (the conventional approach), the
growth in any small region is confined laterally by the growing layer in the neighboring regions. However, when growth occurs
on a reticulated surface, the lateral confinement is removed, providing strain relief and fewer defects. 相似文献
96.
B. J. Skromme E. Luckowski K. Moore M. Bhatnagar C. E. Weitzel T. Gehoski D. Ganser 《Journal of Electronic Materials》2000,29(3):376-383
Electrical properties, including current-voltage (I-V) and capacitance-voltage (C-V) characteristics, have been measured on
a large number of Ti, Ni, and Pt-based Schottky barrier diodes on 4H-SiC epilayers. Various nonideal behaviors are frequently
observed, including ideality factors greater than one, anomalously low I-V barrier heights, and excess leakage currents at
low forward bias and in reverse bias. The nonidealities are highly nonuniform across individual wafers and from wafer to wafer.
We find a pronounced linear correlation between I-V barrier height and ideality factor for each metal, while C-V barrier heights
remain constant. Electron beam induced current (EBIC) imaging strongly suggests that the nonidealities result from localized
low barrier height patches. These patches are related to discrete crystal defects, which become visible as recombination centers
in the EBIC images. Alternative explanations involving generation-recombination current, uniform interfacial layers, and effects
related to the periphery are ruled out. 相似文献
97.
基底亚表面裂纹对减反射膜激光损伤阈值的影响 总被引:1,自引:2,他引:1
利用化学沥滤技术,分析了亚表面裂纹对基底表面和减反射膜激光损伤阈值(LIDT)的影响。通过去除或保留研磨裂纹,获得了亚表面裂纹数密度有明显区别的两类基底。为了凸出亚表面裂纹层的作用,基底采用化学沥滤去除另外一种可能的影响因素,即再沉积层中的抛光杂质。然后采用电子束蒸发镀制HfO2/SiO2减反射膜。355nm激光损伤阈值测试结果和损伤形貌分析证实了基底亚表面裂纹对减反射膜抗激光损伤能力的负面影响。根据熔石英基底抛光表面的烘烤现象,提出了亚表面缺陷影响膜层激光损伤的耦合模型。 相似文献
98.
利用非平衡分子动力学方法研究了空位结构缺陷对Si薄膜热导率的影响。当温度在300K-700K之间变化时,热导率随着空位浓度的增加而降低,并且随着温度的升高空位浓度对热导率的影响以及同一空位浓度下温度对热导率的影响都在逐渐减弱。本文还利用Boltzmann输运理论对MD模拟进行验证,结果基本与其一致。同时理论方法还表明,空位缺陷对薄膜热导率的巨大影响归因于晶格应力的存在使点缺陷也发生散射作用的结果。 相似文献
99.
本文报道应用古代“魔镜”成像原理和现代激光技术发展起来的一种新的光反射“魔镜”检测技术。采用这项技术可以非常直观,方便地观测到直径小于150mm的硅抛光片及硅外延片表面存在的缺陷情况,其分辨率为0.5μm,由于光反射“魔镜”检测技术是一种新型的光学无损检测技术,具有探测灵敏度高,快速,无破坏性,大面积检测等优点,该项技术检测将会有更加广泛的应用前景。 相似文献
100.
Yachin Ivry Colm Durkan Daping Chu James F. Scott 《Advanced functional materials》2014,24(35):5567-5574
Most ferroelectrics are also ferroelastics (hysteretic stress‐strain relationship and response to mechanical stresses). The interactions between ferroelastic twin walls and ferroelectric domain walls are complex and only partly understood, hindering the technological potential of these materials. Here we study via atomic force microscopy the pinning of 180‐degree ferroelectric domain walls in lead zirconate titanate (PZT). Our observations satisfy all three categories of ferroelectric‐ferroelastic domain interaction proposed by Bornarel, Lajzerowicz, and Legrand. 相似文献