全文获取类型
收费全文 | 3014篇 |
免费 | 186篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 83篇 |
综合类 | 11篇 |
化学工业 | 785篇 |
金属工艺 | 83篇 |
机械仪表 | 141篇 |
建筑科学 | 109篇 |
矿业工程 | 3篇 |
能源动力 | 205篇 |
轻工业 | 250篇 |
水利工程 | 46篇 |
石油天然气 | 36篇 |
武器工业 | 2篇 |
无线电 | 244篇 |
一般工业技术 | 553篇 |
冶金工业 | 126篇 |
原子能技术 | 21篇 |
自动化技术 | 528篇 |
出版年
2024年 | 7篇 |
2023年 | 85篇 |
2022年 | 135篇 |
2021年 | 215篇 |
2020年 | 172篇 |
2019年 | 206篇 |
2018年 | 236篇 |
2017年 | 228篇 |
2016年 | 203篇 |
2015年 | 153篇 |
2014年 | 180篇 |
2013年 | 286篇 |
2012年 | 200篇 |
2011年 | 195篇 |
2010年 | 140篇 |
2009年 | 139篇 |
2008年 | 85篇 |
2007年 | 65篇 |
2006年 | 48篇 |
2005年 | 27篇 |
2004年 | 19篇 |
2003年 | 22篇 |
2002年 | 18篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 22篇 |
1997年 | 14篇 |
1996年 | 10篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1976年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有3226条查询结果,搜索用时 15 毫秒
101.
The hypothesis of incorporating carbon nanotubes (CNTs) into the interfacial layers of fiber‐reinforced polymer composites fiber‐reinforced Polymers (FRPs) to enhance their mechanical properties and mitigate the stress wave propagation during a blast event is investigated. A numerical model is developed to simulate the stress wave propagation in a laminated elastic/viscoelastic FRP. Coupled with multiobjective optimization paradigms, the optimal CNTs contents in the interfacial layers are determined to minimize the stress‐to‐strength ratio in each layer. A case study demonstrating the design of a five‐layered FRP subjected to a blast event is presented. The simulation revealed that the viscoelastic properties of the matrix material contribute significantly to the energy dissipation during stress wave propagation. It is shown that addition of 0.69% CNTs by volume to the epoxy interface significantly enhances the ability of composite to resist blast loading. Results were compared with a standard model that assumes only elastic behavior. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers 相似文献
102.
In this paper, a numerically comprehensive investigation have been performed in order to propose a high-κ spacer triple-gate junctionless FinFET (HKS 相似文献
103.
The purpose of this paper is to study the characteristics of the combined convection heat transfer and a micropolar nanofluid flow passing through an impermeable stretching sheet in a porous medium. The nanofluid flow field is affected by a magnetic field perpendicular to the sheet. The dynamic viscosity of the micropolar nanofluid changes under the influence of the magnetic field. The continuity, linear momentum, angular momentum, and energy equations are first simplified using the order of magnitude technique that, along with the applied boundary conditions and the definition of the appropriate parameters, are transferred to the similarity space using the similarity analysis. Then the resulting equations are solved using the Runge–Kutta method.The distinction of the macroscale and microscale flow fields and temperature fields resulting from different nanoparticle shapes was clarified. Increasing the Hartmann number, the vortex viscosity parameter, the magnetic parameter, the nanoparticle volume fraction, and the permeability parameter of the porous media increased the surface friction on the sheet. Increasing the vortex viscosity parameter, the magnetic parameter, and the volume fraction of the nanoparticles increases the Nusselt number. 相似文献
104.
ABSTRACT
A green and efficient dispersive liquid-liquid microextraction method based on a new deep eutectic solvent has been developed for the preconcentration and extraction of cobalt and nickel ions. The deep eutectic solvent is formed by mixing choline chloride (hydrogen bond acceptor) and 4-aminophenol (hydrogen bond donor). Then, it is used as a chelating agent as well as extraction solvent. Under the optimum experimental conditions, the linear ranges for Ni(II) and Co(II) were 0.80–50 and 0.50–50 µgL?1, respectively, by flame atomic absorption spectrometry. The obtained detection limits were 0.30 and 0.22 µg L?1 for Ni(II) and Co(II), respectively. 相似文献
105.
Elahe Sharifisamani Fatemeh Mousazadegan Roohollah Bagherzadeh Masoud Latifi 《Polymer Engineering and Science》2020,60(7):1520-1529
This work presents an interesting method using an electrospinning process to fabricate suture yarns loaded with curcumin to achieve reasonable mechanical properties as well as tunable drug release behavior. Different structures including different yarn counts and twists as well as core-sheath structures were used to adjust drug release properties along with improving the yarn's mechanical properties. The core parts were made of polycaprolactone and the sheath parts were made of polyethylene glycol, polylactic acid, and polycaprolactone. Drugs can be incorporated in both parts based on the required condition and application. Electrospun yarns were compared using both structural properties and their drug release profiles as metrics. The results of comparing drug release profiles of six electrospun yarns with different yarn counts and twists showed that yarns with finer fiber diameters in the core part have more drug release as well as more initial release. Overall evaluations showed that core-sheath drugloaded yarn with appropriate physical and mechanical properties can be a useful material as a drug delivery system to the site of damaged tissue. It can also be concluded that the amount and duration of drug release can be controlled using the structural parameters of electrospun yarns as an engineering tool for designing suture yarns with required properties. 相似文献
106.
Zahra Ghahramani Amir Masoud Arabi Mahdi Shafiee Afarani Mohammad Mahdavian 《International Journal of Applied Ceramic Technology》2020,17(3):1514-1521
In this study, combustion synthesis of cerium oxide nanoparticles was reported using cerium nitrate hexahydrate as starting material as well as urea, glycine, glucose, and citric acid as fuels. The influence of fuel type on structure, microstructure, band gap, and corrosion inhibition was investigated. X-ray diffraction (XRD) patterns and scanning electron microscopy micrographs showed that CeO2 nanoparticles with different morphologies were obtained depending on the fuel type. Microstructural changes from unreacted gel to sponge-like morphologies were resulted by varying the fuel type from urea, glycine, and glucose to citric acid. In addition to Ce–O bonds, Fourier transform infrared analysis showed carbon bonds of carbonaceous compositions from incomplete combustion which were declined during combustion reaction. Furthermore, corrosion analyses showed that samples synthesized using urea fuel released the most Ce+4 ions and could have better protection than other samples. 相似文献
107.
Sadaqat Ali Bilal Anjum Ahmed Hafiz Muzammil Irshad Akolade Idris Bakare Abbas Saeed Hakeem Muhammad Qamaruddin Muhammad Ali Ehsan Sameer Ali Muhammad Umar Azam 《International Journal of Applied Ceramic Technology》2020,17(4):1948-1958
The thermomechanical behavior of micro/nano-alumina (Al2O3) ceramics reinforced with 1-5 wt.% of acid-treated oil fly ash (OFA) was investigated. Composites were sintered using spark plasma sintering (SPS) technique at a temperature of 1400°C by applying a constant uniaxial pressure of 50 MPa. It was evaluated that the fracture toughness of micro- and nanosized composites improved in contrast with the monolithic alumina. Highest fracture toughness value of 4.85 MPam1/2 was measured for the nanosized composite reinforced with 5 wt.% OFA. The thermal conductivity of the composites (nano-/microsized) decreased with the increase in temperature. However, the addition of OFA (1-5 wt.%) in nanosized alumina enhanced the thermal conductivity at an evaluated temperature. Furthermore, a minimum thermal expansion value of 6.17 ppm*K−1 was measured for nanosized Al2O3/5 wt.% OFA composite. Microstructural characterization of Al2O3-OFA composites was done by x-ray diffraction and Raman spectroscopy. Oil fly ash particles were seen to be well dispersed within the alumina matrix. Moreover, the comparative analysis of the nano-/microsized Al2O3/OFA composites shows that the mechanical and thermal properties were improved in nanosized alumina composites. 相似文献
108.
Mehrdad Azamian Jazi Ahmad Ramezani S.A. Seyyed Arash Haddadi Saeed Ghaderi Fariba Azamian 《应用聚合物科学杂志》2020,137(15):48570
Polyvinyl acetate (PVAc) nanocomposites for wood adhesives containing different amounts of colloidal silica nanoparticles (CSNs) were synthesized via in situ one-step emulsion polymerization. The adhesion strength of wood specimens bonded by PVAc nanocomposites was investigated by the tensile test. Thermal properties of PVAc nanocomposites were also characterized by differential scanning calorimetry and thermogravimetric analysis. Rheological and morphological properties of the PVAc nanocomposites were investigated using rheometric mechanical spectrometry and field emission scanning electron microscopy (FESEM), respectively. The obtaining results showed that the shear strength of PVAc nanocomposite including 1 wt. % CSNs has the highest shear and tensile strength about 4.7 and 3.2 MPa, respectively. A small increment of Tg (~3 °C) and considerable increment of the ash content proved the enhancement of PVAc thermal characterization in the presence of CSNs. FESEM results showed uniform dispersion of nanoparticles throughout the PVAc matrix due to using the in situ emulsion polymerization process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48570. 相似文献
109.
Mahdi Norouzi Malihe Tahernejad Seyed Ghorban Hosseini Saeed Tavangar 《化学工程与技术》2020,43(11):2215-2223
The sphericity and size of ammonium perchlorate (AP) particles significantly influence the properties of composite propellants. As the AP particles become more spherical, the accumulation coefficient increases, the viscosity during casting decreases, and the particle loading and burning rate increase. Hence, the production of micronized AP particles with an average size between 1 and 20 μm is important to increase the loading percentage of AP in the composite propellant. Here, the Taguchi experimental design was used to optimize the solvent-antisolvent crystallization (SAC) process for the preparation of micronized AP particles with higher sphericity. SAC parameters such as the type of antisolvent, the solvent-to-antisolvent ratio, the antisolvent temperature, the stirring speed, and the retention time were investigated at four levels. The type of antisolvent and the solvent-to-antisolvent ratio were found to mainly contribute to improving the sphericity and size of the AP particles, respectively. 相似文献
110.
Mahsa Barzegar Rabi Behrooz Hamid Reza Mansouri Saeed Kazemi Najafi Linda F. Lorenz Charles R. Frihart 《Journal of the American Oil Chemists' Society》2020,97(12):1371-1383
Canola is widely grown in the northern latitudes for its vegetable oil, generating large quantities of residual, low value canola flour used as animal feed. The common wood adhesive poly(diphenylmethylene diisocyanate) (pMDI) should react with the wide variety of functional groups in proteins. Therefore, it would seem that canola flour with added pMDI could be an effective adhesive. Two main questions are addressed in this study: How do the wood adhesive properties of canola flour compare to the better-studied soy flour? How well do proteins, which contain an abundance of functional groups, cure with the very reactive pMDI? These questions were addressed using the small-scale adhesive strength test ASTM D-7998, with various adhesive formulations and bonding conditions for canola flour plus pMDI compared to soy adhesives. The more challenging wet cohesive bond strength was emphasized because the dry strengths were usually very good. Generally, soy adhesives were better than canola ones, as was the polyamidoamine-epichlorohydrin cross-linker compared to pMDI, but these generalizations can be altered by the conditions selected. Three-ply plywood tests supported the small-scale test results. 相似文献