全文获取类型
收费全文 | 31135篇 |
免费 | 2219篇 |
国内免费 | 1664篇 |
专业分类
电工技术 | 680篇 |
技术理论 | 1篇 |
综合类 | 1446篇 |
化学工业 | 9400篇 |
金属工艺 | 7006篇 |
机械仪表 | 1287篇 |
建筑科学 | 1664篇 |
矿业工程 | 462篇 |
能源动力 | 983篇 |
轻工业 | 2159篇 |
水利工程 | 278篇 |
石油天然气 | 815篇 |
武器工业 | 256篇 |
无线电 | 1075篇 |
一般工业技术 | 5718篇 |
冶金工业 | 1164篇 |
原子能技术 | 293篇 |
自动化技术 | 331篇 |
出版年
2024年 | 174篇 |
2023年 | 596篇 |
2022年 | 904篇 |
2021年 | 1036篇 |
2020年 | 999篇 |
2019年 | 993篇 |
2018年 | 967篇 |
2017年 | 1210篇 |
2016年 | 1037篇 |
2015年 | 1073篇 |
2014年 | 1571篇 |
2013年 | 2021篇 |
2012年 | 2113篇 |
2011年 | 2288篇 |
2010年 | 1844篇 |
2009年 | 1760篇 |
2008年 | 1464篇 |
2007年 | 1885篇 |
2006年 | 1850篇 |
2005年 | 1574篇 |
2004年 | 1338篇 |
2003年 | 1068篇 |
2002年 | 959篇 |
2001年 | 768篇 |
2000年 | 719篇 |
1999年 | 527篇 |
1998年 | 436篇 |
1997年 | 365篇 |
1996年 | 305篇 |
1995年 | 263篇 |
1994年 | 206篇 |
1993年 | 181篇 |
1992年 | 150篇 |
1991年 | 88篇 |
1990年 | 70篇 |
1989年 | 69篇 |
1988年 | 40篇 |
1987年 | 20篇 |
1986年 | 23篇 |
1985年 | 11篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1965年 | 1篇 |
1959年 | 2篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Ferrite particles coated with biocompatible phases can be used for hyperthermia treatment of cancer. We have synthesized substituted
calcium hexaferrite, which is not stable on its own but is stabilized with small substitution of La. Hexaferrite of chemical
composition (CaO)0.75(La203)0.20(Fe2O3)6 was prepared using citrate gel method. Hydroxyapatite was prepared by precipitating it from aqueous solution of Ca(NO3)2 and (NH4)2HPO4 maintaining pH above 11. Four different methods were used for coating of hydroxyapatite on ferrite particles. SEM with EDX
and X-ray diffraction analysis shows clear evidence of coating of hydroxyapatite on ferrite particles. These coated ferrite
particles exhibited coercive field up to 2 kOe, which could be made useful for hysteresis heating in hyperthermia. Studies
by culturing BHK-21 cells and WBC over the samples show evidence of biocompatibility. SEM micrographs and cell counts give
clear indication of cell growth on the surface of the sample. Finally coated ferrite particle was implanted in Kasaulli mouse
to test its biocompatibility. The magnetic properties and biocompatibility studies show that these hydroxyapatite coated ferrites
could be useful for hyperthermia. 相似文献
2.
H. L. Du S. R. Rose Z. D. Xiang P. K. Datta X. Y. Li 《Materialwissenschaft und Werkstofftechnik》2003,34(4):421-426
The oxidation/sulphidation behaviour of a Ti‐46.7Al‐1.9W‐0.5Si alloy with a TiAl3 diffusion coating was studied in an environment of H2/H2S/H2O at 850oC. The kinetic results demonstrate that the TiAl3 coating significantly increased the high temperature corrosion resistance of Ti‐46.7Al‐1.9W‐0.5Si. The SEM, EDX, XRD and TEM analysis reveals that the formation of an Al2O3 scale on the surface of the TiAl3‐coated sample was responsible for the enhancement of the corroison resistance. The Ti‐46.7Al‐1.9W‐0.5Si alloy was also modified by Nb ion implantation. The Nb ion implanted and as received sampels were subjected to cyclic oxidation in an open air at 800oC. The Nb ion implantation not only increased the oxidation resistance but also substantially improved the adhesion of scale to the substrate. 相似文献
3.
4.
5.
ImprovingWearResistanceoftheNibaseThermalSprayWeldingCoatingUsingRareEarthsZhaiGuangjie(翟光杰)(InstituteofPhysics,AcademicaSi... 相似文献
6.
埋地管道涂层检测技术现状 总被引:3,自引:0,他引:3
李继华 《石油化工腐蚀与防护》1998,15(4):4-6,52
文章对各种埋地管道涂层检测技术进行了综述,并指出了各种技术的优缺点及应用前景. 相似文献
7.
Cypriano G da Trindade Neto Ana LP Fernandes Ana IB Santos Waldenice A Morais Marcos VM Navarro Tereza NC Dantas Mrcia R Pereira Jos LC Fonseca 《Polymer International》2005,54(4):659-666
Complexation of chitosan in aqueous solutions by low molecular weight electrolytes is one of the simplest methods for the preparation of aqueous chitosan dispersions. In this work, the influence of storage time, sulfate concentration, method of preparation and surfactant content on some properties of the resultant chitosan dispersions (turbidity, viscosity and zeta potential) was analyzed. Turbidimetry was adequate to monitor the formation of particles, while viscometry was suitable to monitor changes in the dispersing phase. An analysis of the properties of these systems, mainly in terms of particle–particle and macromolecule–macromolecule interactions was carried out. Copyright © 2004 Society of Chemical Industry 相似文献
8.
Novel polyurethane insulating coatings were prepared from the reaction of glycerin‐terminated polyurethane prepolymers (GPUPs) and a blocked isocyanate curing agent (BIC). The GPUPs were prepared from the reaction of one equivalent of polycaprolactone polyol (CAPA 210) with an excess amount of 4,4′‐methylene bis(phenyl isocyanate) (MDI) and subsequent reaction of the NCO‐terminated polyurethane with glycerin. The BIC was prepared from the reaction of trimethylol propane (TMP), toluene diisocyanate (TDI) and N‐methylaniline (NMA). The polyols and curing agent were characterized by conventional methods while the curing condition was optimized via gel content measurements. The curing kinetics of the polyurethane coating were investigated and the kinetic parameters derived. The crosslink densities of the samples were determined via the equilibrium swelling method, using the Flory–Rehner equation. The relationships between the crosslink density and the electrical, physical, mechanical and dynamic mechanical properties of the coatings were also studied. Copyright © 2005 Society of Chemical Industry 相似文献
9.
10.
The aim of this study was to investigate the drug‐loading effects on release and mechanical properties of a scleroglucan gel, with the intention of considering them in delivery systems formulations. The rheological and kinetic properties of a 2 % w/w scleroglucan gel matrix loaded with 0, 0.02, 0.04, 0.06, 0.2 and 0.4 % w/w of theophylline (Th, used as a model drug) were investigated. Rheological measurements were performed in a controlled‐stress rotational‐shear rheometer under isothermal conditions. For theophylline release from the gel a flat Franz cell was used and the kinetic parameters were derived applying a semi‐empirical power law. The influence of scleroglucan molar weight on kinetic and rheological behaviour was also studied. Results suggest two possible effects of drug loading on the gel network: in the 0.04–0.06 % w/w Th range a plasticizing effect and in the 0.2–0.4 % w/w Th range a rigidization effect. In the first range mentioned, the changes in the gel structural properties tested by means of rheological measurements are coincident with changes in drug‐release kinetics. Copyright © 2005 Society of Chemical Industry 相似文献