全文获取类型
收费全文 | 2615篇 |
免费 | 256篇 |
国内免费 | 12篇 |
学科分类
工业技术 | 2883篇 |
出版年
2024年 | 2篇 |
2023年 | 41篇 |
2022年 | 18篇 |
2021年 | 77篇 |
2020年 | 75篇 |
2019年 | 96篇 |
2018年 | 89篇 |
2017年 | 88篇 |
2016年 | 98篇 |
2015年 | 110篇 |
2014年 | 147篇 |
2013年 | 201篇 |
2012年 | 184篇 |
2011年 | 227篇 |
2010年 | 162篇 |
2009年 | 172篇 |
2008年 | 163篇 |
2007年 | 109篇 |
2006年 | 107篇 |
2005年 | 98篇 |
2004年 | 71篇 |
2003年 | 70篇 |
2002年 | 65篇 |
2001年 | 53篇 |
2000年 | 41篇 |
1999年 | 37篇 |
1998年 | 51篇 |
1997年 | 28篇 |
1996年 | 25篇 |
1995年 | 24篇 |
1994年 | 25篇 |
1993年 | 10篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1976年 | 6篇 |
1974年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有2883条查询结果,搜索用时 15 毫秒
1.
Zakraoui Jezia Saleh Moutaz Al Ja’am Jihad 《Multimedia Tools and Applications》2019,78(16):22833-22859
Multimedia Tools and Applications - Text-to-picture systems attempt to facilitate high-level, user-friendly communication between humans and computers while promoting understanding of natural... 相似文献
2.
The c-axis preferred orientation of ZnO film is the most important factor for its successful application in piezoelectric devices. The effects of surface roughness of the substrate on the c-axis preferred orientation of ZnO thin films, deposited by radio frequency magnetron sputtering, were investigated. During sputtering, the oxygen content in the argon environment used was varied from 0 to 70% at a total sputtering pressure of 10 mTorr. Very smooth Si, smooth evaporated Au/Si, smooth evaporated-Al/Si, and rough sputtered-Al/Si were used as substrates. Their r.m.s. roughnesses, as measured by atomic force microscopy, were 1.27, 17.1, 21.1 and 65-118 Å, respectively. The crystalline structure and the angular spread of the (0 0* 2) plane normal to the ZnO films were determined using X-ray diffraction and X-ray rocking curves, respectively. The crystallinity and the preferred c-axis orientation of the ZnO films were strongly dependent on the surface roughness of the substrates rather than on the oxygen content of the working environment or on the chemical nature of the substrate. 相似文献
3.
Contact angles were measured in the following systems: quartz/water droplet/saturated vapor of water + n-alkane and quartz/water droplet/saturated vapor of n-alkane. The alkanes tested were from hexane to pentadecane. In both systems non-smooth changes of contact angle as a function of the chain length were observed. These changes are similar to the zeta-potential changes measured previously for two different samples of quartz in the quartz/n-alkana/water system. On the basis of the results and calculations it is suggested that the observed non-smooth changes of contact angle are due to similar changes in film pressures of the water and n-alkanes. 相似文献
4.
A simple mathematical analysis on the effect of sand in Cr(VI) reduction using zero valent iron 总被引:1,自引:0,他引:1
A simple mathematical model was proposed to analyze the enhancement of Cr(VI) reduction when sand materials are added to the
zero valent iron (ZVI). Natural decay of Cr(VI) in a control experiment was analyzed by using a zero-order decay reaction.
Adsorption kinetics of Cr(VI) to sand was modeled as a first-order reversible process, and the reduction rate by ZVI was treated
as a first-order reaction. Natural decay of Cr(VI) was also included in other experiments, i.e., the adsorption to sand, the
reduction by ZVI, and both adsorption and reduction when sand and ZVI are present together. The model parameters were estimated
by fitting the solution of each model to the corresponding experimental data. To observe the effect of sand addition to ZVI,
both adsorption and reduction rate models were considered simultaneously including the natural decay. The solution of the
combined model was fitted to the experimental data to determine the first-order adsorption and reduction rate constants when
sand as well as ZVI is present. The first-order reduction rate constant in the presence of sand was about 35 times higher
than that with ZVI only. 相似文献
5.
Chadwin D. Young Gennadi Bersuker Yuegang Zhao Jeff J. Peterson Joel Barnett George A. Brown Jang H. Sim Rino Choi Byoung Hun Lee Peter Zeitzoff 《Microelectronics Reliability》2005,45(5-6):806
Effects of constant voltage stress (CVS) on gate stacks consisting of an ALD HfO2 dielectric with various interfacial layers were studied with time dependent sensing measurements: DC I–V, pulse I–V, and charge pumping (CP) at different frequencies. The process of injected electron trapping/de-trapping on pre-existing defects in the bulk of the high-κ film was found to constitute the major contribution to the time dependence of the threshold voltage (Vt) shift during stress. The trap generation observed with the low frequency CP measurements is suggested to occur within the interfacial oxide layer or the interfacial layer/high-κ interface, with only a minor effect on Vt. 相似文献
6.
Seung-Yeop Kwak 《应用聚合物科学杂志》1995,55(12):1683-1690
The structural changes of poly(vinyl chloride) (PVC) plastisols during mixing of PVC with a plasticizer was investigated; as the temperature was increased, the system was found to transform from a suspension of solid particles in a liquid medium to a swollen gel and ultimately to a fused homogeneous matrix. The dynamic viscoelastic measurements were utilized to continuously monitor the changes of moduli under a controlled heating rate, employing a mechanical spectrometer. Characteristic changes in the viscoelastic behavior were associated with changes in particulate morphology as observed with a scanning electron microscope (SEM). Both viscoelastic and morphological observations were shown to provide details of structural changes in conjunction with the behavior of the PVC–plasticizer interaction, enabling a qualitative discrimination of the gelation and fusion processes. An in situ small-angle light-scattering (SALS) method was performed to make a quantitative estimate for the swollen particles of PVC while they were in the progress of gelation and fusion. From the manner of increase in correlation distances, along with the changes in viscoelastic moduli and morphology, the swelling behavior of the particulate structures were examined on the quantitative basis and brief insight into the complex behavior of the PVC–plasticizer interaction began to be unfolded. © 1995 John Wiley & Sons, Inc. 相似文献
7.
W. J. Kwak J. H. Lee S. M. Hwang Y. H. Kim 《Metallurgical and Materials Transactions A》2002,33(10):3255-3272
Investigated via a series of finite-element (FE) process simulations is the effect of diverse process variables on some selected nondimensional
parameters characterizing the thermomechanical behavior of the strip in hot-strip rolling. Then, on the basis of these parameters
an on-line model is derived for the precise prediction of roll force and roll power. The prediction accuracy of the proposed
model is examined through comparison with predictions from a FE process model and also with measurements. 相似文献
8.
9.
Hun Xue 《Materials Letters》2007,61(2):347-350
Macroporous nanocrystalline zinc ferrite with single spinel-phase was prepared by a facile self-propagating combustion method using zinc nitrate, iron nitrate and glycine. The as-prepared ZnFe2O4 were characterized by X-ray diffraction (XRD) analysis, N2 adsorption, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectrum (EDS). The magnetic properties of the prepared ZnFe2O4 were also studied. 相似文献
10.
In this paper, we propose an efficient design method for area optimization in a digital filter. The conventional methods to reduce the number of adders in a filter have the problem of a long critical path delay caused by the deep logic depth of the filter due to adder sharing. Furthermore, there is such a disadvantage that they use the transposed direct form (TDF) filter which needs more registers than those of the direct form (DF) filter. In this paper, we present a hybrid structure of a TDF and DF based on the flattened coefficients method so that it can reduce the number of flip‐flops and full‐adders without additional critical path delay. We also propose a resource sharing method and sharing‐pattern searching algorithm to reduce the number of adders without deepening the logic depth. Simulation results show that the proposed structure can save the number of adders and registers by 22 and 26%, respectively, compared to the best one used in the past. 相似文献