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排序方式: 共有362条查询结果,搜索用时 15 毫秒
61.
Yasir Amer Al-Jawhar Khairun N. Ramli Montadar Abas Taher Nor Shahida M. Shah Salama A. Mostafa Bashar Ahmed Khalaf 《ETRI Journal》2021,43(2):209-220
The filtered orthogonal frequency division multiplexing (F-OFDM) system has been recommended as a waveform candidate for fifth-generation (5G) communications. The suppression of out-of-band emission (OOBE) and asynchronous transmission are the distinctive features of the filtering-based waveform frameworks. Meanwhile, the high peak-to-average power ratio (PAPR) is still a challenge for the new waveform candidates. Partial transmit sequence (PTS) is an effective technique for mitigating the trend of high PAPR in multicarrier systems. In this study, the PTS technique is employed to reduce the high PAPR value of an F-OFDM system. Then, this system is compared with the OFDM system. In addition, the other related parameters such as frequency localization, bit error rate (BER), and computational complexity are evaluated and analyzed for both systems with and without PTS. The simulation results indicate that the F-OFDM based on PTS achieves higher levels of PAPR, BER, and OOBE performances compared with OFDM. Moreover, the BER performance of F-OFDM is uninfluenced by the use of the PTS technique. 相似文献
62.
Diazotized aryl amines were coupled with 2-aminothiazoles 1 and 2 to give the corresponding thiazolylazo dyes 3 and 4, respectively. 2-Amino-5-arylazothiazoles 5 reacted with chloroacetyl chloride to afford the chloro-acetamide derivatives 6 which further reacted with 2-mercaptobenzothiazole to furnish a new series of 5-arylazothiazolyl dyes 7. The azo structure of the dyes (rather than the tautomeric hydrazo structure) was assessed by ab initio DFT calculations at the B3LYP/6-31G* level. These dyes were applied to polyester fabric as disperse dyes and their fastness properties were evaluated. 相似文献
63.
The stable Euler-number-based image binarization has been shown to give excellent visual results for images containing high amount of image noise. Being computationally expensive, its applications are limited mostly to general-purpose processors and in application specific integrated circuits. In this paper a modified stable Euler-number-based algorithm for image binarization is proposed and its real-time hardware implementation in a Field Programmable Gate Array with a pipelined architecture is presented. The proposed modifications to the algorithm facilitate hardware implementation. The end result is a design that out-performs known software implementations. The amount of noisy pixels introduced during the binarization process is also minimized. Despite the stable Euler-number-based image binarization being computationally expensive, our simulations show that the proposed architecture gives accurate results and this in real time and without consuming all chip resources. 相似文献
64.
Prabhakarn Arunachalam Mabrook S. Amer Mohamed A. Ghanem Abdullah M. Al-Mayouf Dongyuan Zhao 《International Journal of Hydrogen Energy》2017,42(16):11346-11355
This work reports the photodeposition of Ag nanoparticles onto mesoporous TiO2 (m-TiO2) pre-formed by the evaporation-induced self-assembly method. Photoanodes of Ag/m-TiO2 assembled by electrophoretic disclose a superior photoelectrochemical (PEC) performance for water oxidation reaction related to m-TiO2. The photoanodes physicochemical investigations witness the even arrangement of m-TiO2 nanospheres particles over the substrates. The PEC study displays a steady photocurrent density of 1 mAcm?2 at ?1.0 V vs SCE was attained for Ag/m-TiO2 photoanodes in visible light illumination and it is nearly twofold enhancements in comparison with m-TiO2 photoanodes. The observed superior PEC nature was attributed to the reduced band-gap energy and charge recombination that caused from the incorporation of plasmonic photodeposited Ag nanoparticles on m-TiO2 nanospheres photoanodes. 相似文献
65.
Using the alternating directional Galerkin technique we show that the approximate solution of the initial boundary value problem of parabolic partial differential equations is equivalent to the least squares solution of the linear system A B = b. In the full rank case, an efficient method for obtaining the solution of the least squares problem suitable for distributive memory computers was presented in (Fausett et al., 1994). This method is extended to solve the rank deficient case using the RRQR factorization of matrices A and B together with the commutatively property of the Kronecker product. Solution algorithm and parallel implementation are discussed. Timing results are presented and compared with previous work. 相似文献
66.
Amer Jassin Al-Khafaji Mohammed Hail Hakimi Ahmed Askar Najaf 《Egyptian Journal of Petroleum》2018,27(1):117-130
Seven crude oils from Cretaceous Mishrif reservoir rocks in the southern Mesopotamian Basin, South Iraq were studied to describe oil characteristics, providing information on the source of organic matter input and the genetic link between oils and their potential source rock in the basin. This study is based on biomarker and non-biomarker analyses performed on oil samples. The analysed oils are aromatic intermediate oils as indicated by high aromatic hydrocarbon fractions with more that 50%. These oils are also characterized by high sulfur and trace metal (Ni, V) contents and relatively low API gravity values (19.0–27.2° API). The results of this study indicate that these oils were derived from a marine carbonate source rocks bearing Type II-S kerogen that were deposited under sulphate-reducing conditions. This is primary achieved from their biomarkers and bulk carbon isotope and inorganic element contents (i.e., S, Ni and V). The absence of 18a (H)-oleanane biomarker also suggests a source age older than Late Cretaceous. The biomarker characteristics of these oils are consistent with those of the Late Jurassic to Early Cretaceous source rocks in the basin. However, biomarker maturity data also indicate that the oils were generated from early maturity source rocks. This appears to result from the type of kerogen of the source rock, characterized by a high-S kerogen (Type II-S). 相似文献
67.
This paper describes an equation discovery approach based on machine leamng using LAGdtAMGE as an equation discovery tool,with two sources of input,a dataset and model presented in context-free gammar.The approach is searching a large range of potential equations by a specific model.The parameters of the equation are fitted to find the best equations.The The experiments are illustratedwith commodity prices from the London Metal Exchange for the period of January-October 2009.The outputs of the experiments are a large number of equations;same of the equations display that the predicted rakes are following the market trends in perfect patterns. 相似文献
68.
Hemantha Kumar Yeddu Amer MalikJohn Ågren Gustav AmbergAnnika Borgenstam 《Acta Materialia》2012,60(4):1538-1547
In the present work a 3-D elastoplastic phase-field (PF) model is developed, based on the PF microelasticity theory proposed by A.G. Khachaturyan and by including plastic deformation as well as anisotropic elastic properties, for modeling the martensitic transformation (MT) by using the finite-element method. PF simulations in 3D are performed by considering different cases of MT occurring in an elastic material, with and without dilatation, and in an elastic perfectly plastic material with dilatation having isotropic as well as anisotropic elastic properties. As input data for the simulations the thermodynamic parameters corresponding to an Fe-0.3%C alloy as well as the physical parameters corresponding to steels acquired from experimental results are considered. The simulation results clearly show autocatalysis and morphological mirror image formation, which are some of the typical characteristics of a martensitic microstructure. The results indicate that elastic strain energy, anisotropic elastic properties, plasticity and the external clamping conditions affect MT as well as the microstructure. 相似文献
69.
Safaa El-din H. Etaiw Said A. Amer Mohamed M. El-bendary 《Journal of Materials Science》2010,45(5):1307-1314
The self-assembly of K3[Cu(CN)4] and unidentate pyridine bases (L): pyridine (py), 3-methyl pyridine (3-mpy), and 2,4,6-trimethyl pyridine (tmpy) in the
presence of Me3SnCl affords new coordination polymers (CPs) CuCN·0.5(py)] (1), [CuCN·0.5(3-mpy)] (2), and [CuCN·0.5(tmpy)] (3). The syntheses are achieved in H2O/acetonitrile media at room temperature. The structure of the CP 3 was characterized by X-ray single crystal analysis. It is crystallized as orthorhombic in the space group Pnma, a = 9.1065 (3) ?, b = 8.6669 (3) ?, and c = 12.1998 (5) ? and Z = 8. The CPs 1, 2 were investigated by IR, mass, Uv–visible, and 1H-NMR spectra, as well as TGA. The CPs 1–3 are 2D-polymers consisting of 1D-(CuCN)
n
chain structure while the ligands alternate on both sides of the chain with associated copper atom coordination number of
three. Hydrogen bonds play an essential role for developing 2D-network structure. These CPs exhibit strong fluorescent emissions
in the solid state. 相似文献
70.
Fabrega J Tantra R Amer A Stolpe B Tomkins J Fry T Lead JR Tyler CR Galloway TS 《Environmental science & technology》2012,46(2):1128-1135
We studied the effects of ZnO nanoparticles [ZnO NPs, primary particle size 35 ± 10 nm (circular diameter, TEM)], bulk [160 ± 81 nm (circular diameter, TEM)], and Zn ions (from ZnCl(2)) on mortality, growth, and reproductive endpoints in the sediment dwelling marine amphipod Corophium volutator over a complete lifecycle (100 days). ZnO NPs were characterized by size, aggregation, morphology, dissolution, and surface properties. ZnO NPs underwent aggregation and partial dissolution in the seawater exposure medium, resulting in a size distribution that ranged in size from discrete nanoparticles to the largest aggregate of several micrometers. Exposure via water to all forms of zinc in the range of 0.2-1.0 mg L(-1) delayed growth and affected the reproductive outcome of the exposed populations. STEM-EDX analysis was used to characterize insoluble zinc precipitates (sphaerites) of high sulfur content, which accumulated in the hepatopancreas following exposures. The elemental composition of the sphaerites did not differ for ZnO NP, Zn(2+), and bulk ZnO exposed organisms. These results provide an illustration of the comparable toxicity of Zn in bulk, soluble, and nanoscale forms on critical lifecycle parameters in a sediment dwelling organism. 相似文献