全文获取类型
收费全文 | 7454篇 |
免费 | 469篇 |
国内免费 | 255篇 |
专业分类
电工技术 | 343篇 |
综合类 | 352篇 |
化学工业 | 1377篇 |
金属工艺 | 407篇 |
机械仪表 | 357篇 |
建筑科学 | 505篇 |
矿业工程 | 130篇 |
能源动力 | 280篇 |
轻工业 | 455篇 |
水利工程 | 96篇 |
石油天然气 | 260篇 |
武器工业 | 37篇 |
无线电 | 862篇 |
一般工业技术 | 1106篇 |
冶金工业 | 551篇 |
原子能技术 | 85篇 |
自动化技术 | 975篇 |
出版年
2024年 | 23篇 |
2023年 | 104篇 |
2022年 | 178篇 |
2021年 | 277篇 |
2020年 | 234篇 |
2019年 | 217篇 |
2018年 | 200篇 |
2017年 | 215篇 |
2016年 | 259篇 |
2015年 | 207篇 |
2014年 | 304篇 |
2013年 | 440篇 |
2012年 | 399篇 |
2011年 | 478篇 |
2010年 | 380篇 |
2009年 | 366篇 |
2008年 | 382篇 |
2007年 | 347篇 |
2006年 | 370篇 |
2005年 | 342篇 |
2004年 | 222篇 |
2003年 | 232篇 |
2002年 | 182篇 |
2001年 | 187篇 |
2000年 | 147篇 |
1999年 | 204篇 |
1998年 | 219篇 |
1997年 | 159篇 |
1996年 | 152篇 |
1995年 | 130篇 |
1994年 | 103篇 |
1993年 | 88篇 |
1992年 | 57篇 |
1991年 | 58篇 |
1990年 | 47篇 |
1989年 | 41篇 |
1988年 | 34篇 |
1987年 | 24篇 |
1986年 | 33篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 13篇 |
1982年 | 13篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1978年 | 5篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1974年 | 5篇 |
排序方式: 共有8178条查询结果,搜索用时 10 毫秒
31.
A new design of the liquid crystal lenticular (LCL) lens array with interlaced electrodes is proposed to realize an auto-stereoscopic 3D display. The structure of interlaced electrodes aims to generate a desired non-uniform electric filed to improve the focusing ability of the LCL-lens array with lower voltage drives. This paper is organized as first to describe the design criteria of a lenticular lens sheet for wide extended graphics array LCD panel. Based on the designed lenticular lens array, an LCL-lens array with proposed interlaced electrodes is next designed. The fabrication and the detailed structure are given. A series of experiments are then conducted and successfully verify the focusing capability and desired 3D display functions, that is, to separate two images to right and left eyes. Also, the developed auto-stereoscopic 3D display is able to adapt to varied viewer locations with favorable imaging quality. 相似文献
32.
33.
Tuan D. Pham Dinh T.P. Le Jinwei Xu Duc T. Nguyen Robert G. Martindale Clifford W. Deveney 《Computer methods and programs in biomedicine》2014
An abdominal wall hernia is a protrusion of the intestine through an opening or area of weakness in the abdominal wall. Correct pre-operative identification of abdominal wall hernia meshes could help surgeons adjust the surgical plan to meet the expected difficulty and morbidity of operating through or removing the previous mesh. First, we present herein for the first time the application of image analysis for automated identification of hernia meshes. Second, we discuss the novel development of a new entropy-based image texture feature using geostatistics and indicator kriging. Third, we seek to enhance the hernia mesh identification by combining the new texture feature with the gray-level co-occurrence matrix feature of the image. The two features can characterize complementary information of anatomic details of the abdominal hernia wall and its mesh on computed tomography. Experimental results have demonstrated the effectiveness of the proposed study. The new computational tool has potential for personalized mesh identification which can assist surgeons in the diagnosis and repair of complex abdominal wall hernias. 相似文献
34.
The gamma-2 phase (Sn8Hg) and a dental amalgam in phosphate buffer have been studied by means of potentiostatic and galvanostatic techniques, along with a rotating ring-disc electrode (RRDE). The analysis of results has shown that phosphate ions play an important role in the corrosion of amalgam. The anodic reaction leads to the formation of soluble species and a passivating film, which is probably composed of tin hydroxide and tin phosphate. 相似文献
35.
Copolymers of poly(acrylamide-co-acryloyloxyethyltrimethylammonium chloride or AM–CMA) and poly(acrylamide-co-methacryloyloxyethyltrimethylammonium chloride or AM–CMA) prepared by inverse emulsion polymerization were characterized by different analytical techniques. The chemical composition of the copolymers was estimated by elemental analysis and by nuclear magnetic resonance spectroscopy (NMR). NMR spectroscopy and computer simulation were further used for investigating the polymers' sequence distribution. The poly(AM–CMA) copolymers are chemically more homogeneous than are the poly(AM–CMA). The configurational propagation of dyads and triads for the homopolymers obeys Bernouilli's statistics. For the copolymers, the chemical sequences distribution is governed by Markov's first-order statistics. 相似文献
36.
间二甲苯-磷酸-水三元体系的液-液相平衡 总被引:1,自引:0,他引:1
实验测定了不同温度下,间二甲苯-水二元体系和间二甲苯-磷酸-水三元体系的液-液相平衡数据。研究了磷酸中的杂质Fe~(3+)、Al~(3+)和Mg~(2+)对间二甲苯-磷酸-水三元体系相平衡的影响,以及杂质在两相中的分配情况。研究结果对共沸精馏浓缩磷酸提供了必要的理论依据和基础数据。 相似文献
37.
For oil sand extractions with microemulsions it is important to disperse large quantities of light hydrocarbons in an aqueous medium. Fundamental studies on the properties of 2-butoxyethanol (BE) and diethylmethylamine (Et2McN) in water suggest that these two liquids could be more effective cosurfactants than the usual alcohols used for this purpose. The phase diagrams of microemulsions using BE and Et2MeN as cosurfactants, combined with typical ionic and non-ionic surfactants and typical aliphatic and aromatic hydrocarbons, were therefore investigated and compared with microemulsions based on n-butanol. Although the phase diagrams depend significantly on the nature of the surfactant and of the oil, the monophasic region generally increases with the cosurfactant in the order n-butanol < Et2McN < BE. With the active mixture BE-cetyltrimethylammonium bromide, temperature has little effect on the phase diagram and NaCl generally destabilizes the microemulsion. 相似文献
38.
General-base catalysis in the active site of serine proteasesis carried out by the imidazole side chain of a histidine. Duringformation of the transition state, an adjacent carboxylic acidgroup stabilizes the positive charge that forms on the general-basecatalyst and as a result contributes several orders of magnitudeto the catalytic efficiency of these enzymes. In the recentlydiscovered family of self-cleaving proteins exemplified by theLexA repressor of Escherichia coli, instead of the imidazoleof a histidine, the active-site general-base catalyst was foundto be the -amino of a lysine. The considerably higher capacityof the lysine side chain for proton acceptance raises interestingquestions concerning the role of electrostatic interactionsin the mechanism of proton transfer by this highly basic group.The negative charge elimination studies described here and theireffects on the kmax and pK of LexA self-cleavage are consistentwith a model in which electrostatic interactions between anacidic side chain and the general-base catalyst form a barrierto proton transfer. The implications are that the -amino group,unlike the imidazole group, is capable of effecting proton transferwithout the intervention of a countercharge. 相似文献
39.
目的 生成式对抗网络(generative adversarial network,GAN)是一种无监督生成模型,通过生成模型和判别模型的博弈学习生成图像。GAN的生成模型是逐级直接生成图像,下级网络无法得知上级网络学习的特征,以至于生成的图像多样性不够丰富。另外,随着网络层数的增加,参数变多,反向传播变得困难,出现训练不稳定和梯度消失等问题。针对上述问题,基于残差网络(residual network,ResNet)和组标准化(group normalization,GN),提出了一种残差生成式对抗网络(residual generative adversarial networks,Re-GAN)。方法 Re-GAN在生成模型中构建深度残差网络模块,通过跳连接的方式融合上级网络学习的特征,增强生成图像的多样性和质量,改善反向传播过程,增强生成式对抗网络的训练稳定性,缓解梯度消失。随后采用组标准化(GN)来适应不同批次的学习,使训练过程更加稳定。结果 在Cifar10、CelebA和LSUN数据集上对算法的性能进行测试。Re-GAN的IS (inception score)均值在批次为64时,比DCGAN (deep convolutional GAN)和WGAN (Wasserstein-GAN)分别提高了5%和30%,在批次为4时,比DCGAN和WGAN分别提高了0.2%和13%,表明无论批次大小,Re-GAN生成图像具有很好的多样性。Re-GAN的FID (Fréchet inception distance)在批次为64时比DCGAN和WGAN分别降低了18%和11%,在批次为4时比DCGAN和WGAN分别降低了4%和10%,表明Re-GAN生成图像的质量更好。同时,Re-GAN缓解了训练过程中出现的训练不稳定和梯度消失等问题。结论 实验结果表明,在图像生成方面,Re-GAN的生成图像质量高、多样性强;在网络训练方面,Re-GAN在不同批次下的训练具有更好的兼容性,使训练过程更加稳定,梯度消失得到缓解。 相似文献
40.
针对弧光保护系统的实际需要,设计了一种基于SPI的双机通信系统。简要阐述了该系统的设计思路,并给出了具体的实现方法。实验表明,采用该方法能够满足实际工程中的需求,对于其他SPI的应用也有很好的借鉴价值。 相似文献