全文获取类型
收费全文 | 607篇 |
免费 | 45篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 8篇 |
综合类 | 3篇 |
化学工业 | 145篇 |
金属工艺 | 29篇 |
机械仪表 | 37篇 |
建筑科学 | 9篇 |
能源动力 | 28篇 |
轻工业 | 74篇 |
水利工程 | 6篇 |
石油天然气 | 17篇 |
无线电 | 61篇 |
一般工业技术 | 135篇 |
冶金工业 | 30篇 |
原子能技术 | 9篇 |
自动化技术 | 65篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 35篇 |
2020年 | 28篇 |
2019年 | 39篇 |
2018年 | 33篇 |
2017年 | 45篇 |
2016年 | 36篇 |
2015年 | 29篇 |
2014年 | 38篇 |
2013年 | 57篇 |
2012年 | 44篇 |
2011年 | 48篇 |
2010年 | 39篇 |
2009年 | 32篇 |
2008年 | 28篇 |
2007年 | 18篇 |
2006年 | 12篇 |
2005年 | 11篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1984年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有656条查询结果,搜索用时 15 毫秒
51.
Alireza MASOUDIAN Arvin TAHAEI Atefeh SHAKIBA Fariborz SHARIFIANJAZI Jamshid Aghazadeh MOHANDESI 《中国有色金属学会会刊》2014,(5)
对3 mm厚的AZ31-O镁合金板和6061-T6铝合金板进行异种材料搅拌摩擦焊。实验中搅拌针的旋转速度为600~1400 r/min,前进速度为20~60 mm/min。结果表明,在旋转速度1000 r/min、前进速度40 mm/min的工艺条件下,可以获得无缺陷的焊接接头。组织观察发现搅拌区的晶粒尺寸要比基材区的明显小很多。在搅拌区形成了复杂的金属流动。显微硬度测试表明搅拌区的硬度分别是不均匀的。拉伸实验结果表明,接头的拉伸强度约为基材AZ31镁合金的76%,或6061铝合金的60%。接头拉伸断口SEM形貌观察表明为脆性断裂。 相似文献
52.
A method was suggested for the cyclotron production of 88Y with liquid-liquid extraction. The sedimented natSrCO3 target was irradiated with 18-MeV protons at current of 20 μA for 10 h. The 88Y yields of about 1.326 MBq μA−1 h−1 were experimentally obtained. Solvent extraction of no-carrier-added 88Y from irradiated strontium carbonate target in the hydrochloric acid solution was studied using di(2-ethylhexyl) hydrogen
phosphate (HDEHP). The optimum separation was achieved in the system n-hexane/10% HDEHP-0.1 M HCl. Yttrium radionuclides were recovered from the HDEHP phase by stripping with 60 ml of 9 M HC1.
Also, excitation functions of the proton, deuteron, and α-particle induced reactions of 89Y, 88Sr, natSr, and natRb were determined using computer codes and compared to the existing data. 相似文献
53.
54.
Sana Pirmardvand Chegini Jaleh Varshosaz Hamid Mirmohammad Sadeghi Alireza Dehghani Mohsen Minayian 《IET nanobiotechnology / IET》2019,13(9):974
Poly(glycerol sebacate) (PGS) is a new biodegradable polymer with good biocompatibility used in many fields of biomedicine and drug delivery. Sunitinib‐loaded PGS/gelatine nanoparticles were prepared by the de‐solvation method for retinal delivery and treatment of diabetic retinopathy. The nanoparticles were characterised by Fourier‐transform infrared and differential scanning calorimetry. The effects of different formulation variables including drug‐to‐carrier ratio, gelatine‐to‐PGS ratio, and glycerine‐to‐sebacate ratio were assessed on the encapsulation efficiency (EE%), particle size, release efficiency (RE), and zeta potential of the nanoparticles. The in vitro cytotoxicity of PGS/gelatine nanoparticles was studied on L929 cells. Draize test on rabbit eyes was also done to investigate the possible allergic reactions caused by the polymer. Glycerine/sebacic acid was the most effective parameter on the EE and RE. Gelatine‐to‐PGS ratio had the most considerable effect on the particle size while the RE was more affected by the glycerine/sebacic acid ratio. The optimised formulation (S1 G0.7 D21.2) exhibited a particle size of 282 nm, 34.6% EE, zeta potential of −8.9 mV, and RE% of about 27.3% for drug over 228 h. The 3‐(4,5‐dimethylthuazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay indicated PGS/gelatine nanoparticles were not cytotoxic and sunitinib‐loaded nanoparticles were not toxic at concentrations <36 nM.Inspec keywords: polymers, differential scanning calorimetry, toxicology, drug delivery systems, solvation, eye, encapsulation, particle size, drugs, biodegradable materials, nanofabrication, nanomedicine, nanoparticles, gelatin, Fourier transform infrared spectraOther keywords: gelatine‐to‐PGS ratio, glycerine‐to‐sebacate ratio, particle size, zeta potential, sunitinib‐loaded nanoparticles, biodegradable polymer, retinal delivery, differential scanning calorimetry, drug‐to‐carrier ratio, allergic reactions, physicochemistry, cytotoxicity, poly(glycerol sebacate) nanoparticles, sunitinib ocular delivery, drug delivery, sunitinib‐loaded PGS‐gelatine nanoparticles, Fourier‐transform, in vitro cytotoxicity, biocompatibility, Draize test, rabbit eyes, 3‐(4,5‐dimethylthuazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay 相似文献
55.
Asphalt in a colloidal context can be considered as a sol, sol-gel or gel type where in all three cases the asphaltene particle plays an important role. Usually the three colloidal types can be differentiated by refinery processes or by rheological properties. The aggregation or clustering of the asphaltene particles (or micelles) from sol to sol-gel and finally to the gel state with a fixed lattice can follow the stochastic process of fractal Brownian motion which can fit a hyperbolic (or Korcak) distribution. A test was carried out using the same mass of various asphalts of different colloidal types for floc formation with a series of n-alkanes (dispersion media) of increasing characteristic lengths. Results from floc formation studies indicate that the value of the size distribution for the gel type is small, is higher for the sol-gel type, and is highest for the sol type. On the other hand, the surface irregularities for all three types of asphalt do not have any correlation. These observed facts are consistent with principles based on the fractal approach. 相似文献
56.
Alireza Afsharpour Atefeh Afsharpour Mohammad Mohammadi-Khanaposhtani 《Petroleum Science and Technology》2017,35(3):299-305
In this survey, we use the emPR-CPA equation of state to model a ternary system of H2S solubility in MDEA aqueous solution at different solution compositions, temperatures, pressures, and acid gas loadings. For electrolyte part of the model, MSA theory and the Born term were used. There were 302 experimental data used in this work. To model a ternary system, at first pure components, then binary subsystems, and finally ternary system were modeled using a reactive bubble point pressure calculation method. An overall absolute average deviation percentage equal to 20.85 was achieved so that show the model efficiency for correlation of such systems. 相似文献
57.
M. Gazanfari M. Karimzadeh S. Ghorbani M. R. Sadeghi G. Azizi H. Karimi N. Fattahi Z. Karimzadeh 《Bulletin of Materials Science》2014,37(4):871-876
Aluminium nanoparticles (Al Nps) are synthesized using arc discharge method by applying direct current between aluminium electrodes in liquid environment without any use of vacuum equipment, heat exchangers, high temperatures furnaces and inert gases. After synthesis of Al Nps, in situ coating process on the nanoparticles was performed immediately. The effects of media on the yield and morphology of aluminium nanoparticles were investigated. Analysis result of the samples indicated that particle size was less than 30 nm, when 120 A/cm2 arc current was used. In addition, coating agent can affect arc velocity, arc stability, morphology and composition of the nanoparticles. Resultant nanoparticles were identified using X-ray powder diffraction (XRD), also their surface morphology was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and finally the accuracy of coating was assessed with infrared (IR) spectroscopy. 相似文献
58.
Alireza Ahadpour Shal Atefeh Jafari 《Journal of Superconductivity and Novel Magnetism》2014,27(6):1531-1538
In this work, Fe3O4–ZnO core–shell nanoparticles have been successfully synthesized using a simple two-step co-precipitation method. In this regard, Fe3O4 (magnetite) and ZnO (zincite) nanoparticles (NPs) were synthesized separately. Then, the surface of the Fe3O4 NPs was modified with trisodium citrate in order to improve the attachment of ZnO NPs to the surface of Fe3O4 NPs. Afterwards, the modified magnetite NPs were coated with ZnO NPs. Moreover, the influence of the core to shell molar ratio on the structural and magnetic properties of the core–shell NPs has been investigated. The prepared nanoparticles have been characterized utilizing transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and vibrating sample magnetometer (VSM). The results of XRD indicate that Fe3O4 NPs with inverse spinel phase were formed. The results of VSM imply that the Fe3O4–ZnO core–shell NPs are superparamagnetic. The saturation magnetization of prepared Fe3O4 NPs is 54.24 emu/g and it decreases intensively down to 29.88, 10.51 and 5.75 emu/g, after ZnO coating with various ratios of core to shell as 1:1, 1:10 and 1:20, respectively. This reduction is attributed to core–shell interface effects and shielding. TEM images and XRD results imply that ZnO-coated magnetite NPs are formed. According to the TEM images, the estimated average size for most of core–shell NPs is about 12 nm. 相似文献
59.
A new brachytherapy (125)I source has been investigated at Iranian Agricultural, Medical and Industrial Research School. Dosimetric characteristics [dose-rate constant Λ, radial dose function g(l)(r) and anisotropy function F(r,)] of IRA-(125)I were theoretically determined in terms of the updated AAPM task group 43 (TG-43U1) recommendations. Versions 5 and 4C of the Monte Carlo radiation transport code were used to calculate the dosimetry parameters around the source. The Monte Carlo calculated dose-rate constant of the (125)I source in water was found to be 92×10(-4) Gy h(-1) U(-1) with an approximate uncertainty of ±3 %. Brachytherapy seed model, 6711-(125)I, carrying (125)I radionuclides, was modelled and benchmarked against previously published values. Finally, the calculated results were compared with the published results of those of other source manufacturers. 相似文献
60.