全文获取类型
收费全文 | 2948篇 |
免费 | 187篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 63篇 |
综合类 | 3篇 |
化学工业 | 610篇 |
金属工艺 | 102篇 |
机械仪表 | 209篇 |
建筑科学 | 62篇 |
矿业工程 | 3篇 |
能源动力 | 131篇 |
轻工业 | 223篇 |
水利工程 | 10篇 |
石油天然气 | 2篇 |
无线电 | 562篇 |
一般工业技术 | 594篇 |
冶金工业 | 221篇 |
原子能技术 | 34篇 |
自动化技术 | 317篇 |
出版年
2024年 | 4篇 |
2023年 | 40篇 |
2022年 | 44篇 |
2021年 | 83篇 |
2020年 | 77篇 |
2019年 | 76篇 |
2018年 | 97篇 |
2017年 | 100篇 |
2016年 | 103篇 |
2015年 | 90篇 |
2014年 | 138篇 |
2013年 | 147篇 |
2012年 | 188篇 |
2011年 | 219篇 |
2010年 | 181篇 |
2009年 | 192篇 |
2008年 | 144篇 |
2007年 | 150篇 |
2006年 | 116篇 |
2005年 | 113篇 |
2004年 | 97篇 |
2003年 | 83篇 |
2002年 | 80篇 |
2001年 | 65篇 |
2000年 | 66篇 |
1999年 | 57篇 |
1998年 | 99篇 |
1997年 | 78篇 |
1996年 | 34篇 |
1995年 | 36篇 |
1994年 | 16篇 |
1993年 | 24篇 |
1992年 | 18篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有3146条查询结果,搜索用时 15 毫秒
81.
W. S. Lyoo J. H. Kim W. S. Yoon B. C. Ji J. H. Choi J. Cho J. Lee S. B. Yang Y. Yoo 《Polymer》2000,41(26):773-9062
To produce various biodegradable poly(butylene succinate) (PBS) films for particular use, the effects of initial polymer concentration and zone drawing on the structure, physical properties, and hydrolytic degradation of PBS film were investigated. PBS films were prepared from chloroform solutions with different initial concentrations of 8, 11, 14, 17 and 20 g/dl. In order to investigate the drawing behavior of the PBS films with different solution concentrations, the films were drawn under various zone drawing conditions. Through a series of experiments, it turned out that the initial concentration of PBS solution in chloroform caused significant changes in the draw ratio of the PBS film. That is, the zone draw ratios of the film at initial concentration of 14 g/dl exhibited its maximum values and gradually decreased at higher or lower concentrations. Thus, it was concluded that the initial concentration of 14 g/dl is the optimum polymer concentration to produce maximum draw ratio in this work. In addition, the crystal and amorphous orientations and tensile properties of PBS film having similar draw ratio and similar crystallinity were highest at 14 g/dl and surface crystal morphologies of these films were absolutely different. The hydrolytic degradation rate of the film at 14 g/dl was lowest, but with similar draw ratio, film dimension, and crystallinity, indicating that the degradation behaviors were greatly affected by the initial polymer concentration, orientation, and crystal morphology. 相似文献
82.
Md Saifur Rahman Md Badrul Alam Young Kyun Kim Mst Hur Madina Ismail Fliss Sang Han Lee Jin Cheol Yoo 《International journal of molecular sciences》2021,22(10)
In this study, we investigate the immunomodulatory effects of a novel antimicrobial peptide, YD1, isolated from Kimchi, in both in vitro and in vivo models. We establish that YD1 exerts its anti-inflammatory effects via up-regulation of the Nrf2 pathway, resulting in the production of HO-1, which suppresses activation of the NF-κB pathway, including the subsequent proinflammatory cytokines IL-1β, IL-6, and TNF-α. We also found that YD1 robustly suppresses nitric oxide (NO) and prostaglandin E2 (PGE2) production by down-regulating the expression of the upstream genes, iNOS and COX-2, acting as a strong antioxidant. Collectively, YD1 exhibits vigorous anti-inflammatory and antioxidant activity, presenting it as an interesting potential therapeutic agent. 相似文献
83.
Simulation of DME synthesis from coal syngas by kinetics model 总被引:1,自引:0,他引:1
Hyun Min Shim Seung Jong Lee Young Don Yoo Yong Seung Yun Hyung Taek Kim 《Korean Journal of Chemical Engineering》2009,26(3):641-648
DME (Dimethyl Ether) has emerged as a clean alternative fuel for diesel. There are largely two methods for DME synthesis.
A direct method of DME synthesis has been recently developed that has a more compact process than the indirect method. However,
the direct method of DME synthesis has not yet been optimized at the face of its performance: yield and production rate of
DME. In this study it is developed a simulation model through a kinetics model of the ASPEN plus simulator, performed to detect
operating characteristics of DME direct synthesis. An overall DME synthesis process is referenced by experimental data of
3 ton/day (TPD) coal gasification pilot plant located at IAE in Korea. Supplying condition of DME synthesis model is equivalently
set to 80 N/m3 of syngas which is derived from a coal gasification plant. In the simulation it is assumed that the overall DME synthesis
process proceeds with steadystate, vapor-solid reaction with DME catalyst. The physical properties of reactants are governed
by Soave-Redlich-Kwong (SRK) EOS in this model. A reaction model of DME synthesis is considered that is applied with the LHHW
(Langmuir-Hinshelwood Hougen Watson) equation as an adsorption-desorption model on the surface of the DME catalyst. After
adjusting the kinetics of the DME synthesis reaction among reactants with experimental data, the kinetics of the governing
reactions inner DME reactor are modified and coupled with the entire DME synthesis reaction. For validating simulation results
of the DME synthesis model, the obtained simulation results are compared with experimental results: conversion ratio, DME
yield and DME production rate. Then, a sensitivity analysis is performed by effects of operating variables such as pressure,
temperature of the reactor, void fraction of catalyst and H2/CO ratio of supplied syngas with modified model. According to simulation results, optimum operating conditions of DME reactor
are obtained in the range of 265–275 °C and 60 kg/cm2. And DME production rate has a maximum value in the range of 1–1.5 of H2/CO ratio in the syngas composition. 相似文献
84.
Jae-Hee Han Su Hong Lee A.S. Berdinsky Yong Weon Kim Ji-Beom Yoo Chong-Yun Park Jin Ju Choi Taewon Jung In Taek Han Jong Min Kim 《Diamond and Related Materials》2005,14(11-12):1891
In this report, the FE characteristics of carbon nanotubes (CNTs) treated using both thermal annealing and mechanical coatings on the as-grown CNTs systematically studied. It was found that in the high temperature annealed samples, CNTs were attacked at its root during annealing due to a small amount of oxygen, and were pulled out of the substrate in places after FE measurements because of the contact resistance. However, for the mechanically coated samples both with spin on glass (SOG) and polymethyl methacrylate (PMMA), CNTs were found to be nearly intact after FE measurements and showed reliable FE characteristics over repeatable voltage scan. The reliability of CNTs during FE could be owing to the strong adhesion of CNTs to the substrate both by SOG and PMMA coatings. 相似文献
85.
Synthesis and properties of click coupled graphene oxide sheets with three‐dimensional macromolecules 下载免费PDF全文
Sibdas Singha Mahapatra Madeshwaran Sekkarapatti Ramasamy Hye Jin Yoo Dong Hun Yi Jae Whan Cho 《应用聚合物科学杂志》2016,133(17)
A facile click chemistry approach to the functionalization of three‐dimensional hyperbranched polyurethane (HPU) to graphene oxide (GO) nanosheets is presented. HPU‐functionalized GO samples of various compositions were synthesized by reacting alkyne‐functionalized HPU with azide‐functionalized GO sheets. The morphological characterization of the HPU‐functionalized GO was performed using transmission electron microscopy and its chemical characterization was carried out using Fourier transform‐infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X‐ray photoelectron spectroscopy. The graphene sheet surfaces were highly functionalized, leading to improved solubility in organic solvents, and consequently, enhanced mechanical, thermal, and thermoresponsive and photothermal shape memory properties. The strategy reported herein provides a very efficient method for regulating composite properties and producing high performance materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43358. 相似文献
86.
Moon Sam Shin Ki-Pung Yoo Chul Soo Lee Hwayong Kim 《Korean Journal of Chemical Engineering》2006,23(3):469-475
A multi-fluid nonrandom lattice fluid model with no temperature dependence of close packed volumes of a mer, segment numbers
and energy parameters of pure systems is presented. The multi-fluid nonrandom lattice fluid (MF-NLF) model with the local
composition concept was capable of describing properties for complex systems. However, the MF-NLF model has strong temperature
dependence of energy parameters and segment numbers of pure systems; thus empirical correlations as functions of temperature
were represented for reliable and convenient use in engineering practices. The MF-NLF model without temperature dependence
of pure parameters could not predict thermodynamic properties accurately. It was found that the present model with three parameters
describes quantitatively the vapor pressure and the saturated density for the pure fluid. 相似文献
87.
Determination of twisting angle of electrospun nanofiber bundle for continuous electrospinning system 下载免费PDF全文
Electrospinning continuously produced twisted nanofibers with a convergence coil and a rotating ring collector. The positively charged nozzle was used in the electrospinning process to deposit electrospun fibers of polyacrylonitrile onto a rotating ring collector. By withdrawing the electrospun fibers from the rotating ring collector, it was possible to spin the electrospun fibers yarn. In this study, theoretical approaches and numerical simulations were used to determine the twisting angle of the yarn. Using the equations developed in this study, we performed numerical simulations and compared the experimental results with the numerical simulation results. Mechanical properties of the fiber bundle were analyzed for twisting angle. It was confirmed the relationship among the winding drum, the ring collector, and flux of the fibers mass per time during electrospinning in the developed system. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45528. 相似文献
88.
Hydrogen sulfide gas was removed in a 2-dimensional gas-lift reactor by the photosynthetic microorganismChlorobium thiosulfatophilum using light emitting diodes (LEDs) as a light source. LEDs saved light energy by 99% compared with the incandescent light
source. The plate-type gas-lift reactor removed hydrogen sulfide five times better per unit mg of protein, and performed two
times better in the maximum performance per unit luminous flux, compared with cylindrical fermentors. 相似文献
89.
Hee Jeong Yoo Kyung Kim In Hyang Kim Seong-Hwan Rho Jong-Eun Park Ki Young Lee Soon Ae Kim Byung Yoon Choi Namshin Kim 《International journal of molecular sciences》2015,16(3):5697-5713
Rubinstein-Taybi syndrome (RSTS) is a rare condition with a prevalence of 1 in 125,000–720,000 births and characterized by clinical features that include facial, dental, and limb dysmorphology and growth retardation. Most cases of RSTS occur sporadically and are caused by de novo mutations. Cytogenetic or molecular abnormalities are detected in only 55% of RSTS cases. Previous genetic studies have yielded inconsistent results due to the variety of methods used for genetic analysis. The purpose of this study was to use whole exome sequencing (WES) to evaluate the genetic causes of RSTS in a young girl presenting with an Autism phenotype. We used the Autism diagnostic observation schedule (ADOS) and Autism diagnostic interview revised (ADI-R) to confirm her diagnosis of Autism. In addition, various questionnaires were used to evaluate other psychiatric features. We used WES to analyze the DNA sequences of the patient and her parents and to search for de novo variants. The patient showed all the typical features of Autism, WES revealed a de novo frameshift mutation in CREBBP and de novo sequence variants in TNC and IGFALS genes. Mutations in the CREBBP gene have been extensively reported in RSTS patients, while potential missense mutations in TNC and IGFALS genes have not previously been associated with RSTS. The TNC and IGFALS genes are involved in central nervous system development and growth. It is possible for patients with RSTS to have additional de novo variants that could account for previously unexplained phenotypes. 相似文献
90.
The BiVO4 additive was found effective for low-temperature firing of ZnNb2 O6 polycrystalline ceramics below 950°C in air without a serious degradation in their microwave dielectric properties. Dense BiVO4 -doped ZnNb2 O6 samples of a relative sintered density over 95% could be prepared even at 925°C. An optimally processed specimen exhibited excellent microwave dielectric properties of Q · f = 55000 GHz, ɛr = 26, and τf =−57 ppm/°C. With increasing BiVO4 addition up to 20 mol% relative to ZnNb2 O6 , while the quality factor Q · f was gradually decreased, the relative dielectric constant, ɛr , was linearly increased and the temperature coefficient of resonant frequency, τf , was slightly increased. The variations in Q · f and ɛr are surely attributable to the residual BiVO4 in the ZnNb2 O6 matrix. An unexpected slight increase in τf is probably due to the formation of the Bi(V,Nb)O4 -type solid solution. 相似文献