全文获取类型
收费全文 | 5660篇 |
免费 | 950篇 |
国内免费 | 156篇 |
专业分类
电工技术 | 44篇 |
综合类 | 225篇 |
化学工业 | 1623篇 |
金属工艺 | 853篇 |
机械仪表 | 158篇 |
建筑科学 | 386篇 |
矿业工程 | 346篇 |
能源动力 | 198篇 |
轻工业 | 485篇 |
水利工程 | 111篇 |
石油天然气 | 62篇 |
武器工业 | 13篇 |
无线电 | 240篇 |
一般工业技术 | 1243篇 |
冶金工业 | 645篇 |
原子能技术 | 80篇 |
自动化技术 | 54篇 |
出版年
2024年 | 31篇 |
2023年 | 153篇 |
2022年 | 156篇 |
2021年 | 268篇 |
2020年 | 277篇 |
2019年 | 214篇 |
2018年 | 255篇 |
2017年 | 235篇 |
2016年 | 274篇 |
2015年 | 286篇 |
2014年 | 332篇 |
2013年 | 575篇 |
2012年 | 285篇 |
2011年 | 384篇 |
2010年 | 250篇 |
2009年 | 276篇 |
2008年 | 246篇 |
2007年 | 293篇 |
2006年 | 288篇 |
2005年 | 227篇 |
2004年 | 192篇 |
2003年 | 184篇 |
2002年 | 156篇 |
2001年 | 114篇 |
2000年 | 106篇 |
1999年 | 119篇 |
1998年 | 82篇 |
1997年 | 55篇 |
1996年 | 60篇 |
1995年 | 55篇 |
1994年 | 45篇 |
1993年 | 36篇 |
1992年 | 49篇 |
1991年 | 41篇 |
1990年 | 36篇 |
1989年 | 23篇 |
1988年 | 8篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 29篇 |
1984年 | 19篇 |
1983年 | 14篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 6篇 |
排序方式: 共有6766条查询结果,搜索用时 15 毫秒
191.
Gra?yna A. P?aza Joanna Chojniak Ibrahim M. Banat 《International journal of molecular sciences》2014,15(8):13720-13737
Developing a reliable experimental protocol for the synthesis of nanomaterials is one of the challenging topics in current nanotechnology particularly in the context of the recent drive to promote green technologies in their synthesis. The increasing need to develop clean, nontoxic and environmentally safe production processes for nanoparticles to reduce environmental impact, minimize waste and increase energy efficiency has become essential in this field. Consequently, recent studies on the use of microorganisms in the synthesis of selected nanoparticles are gaining increased interest as they represent an exciting area of research with considerable development potential. Microorganisms are known to be capable of synthesizing inorganic molecules that are deposited either intra- or extracellularly. This review presents a brief overview of current research on the use of biosurfactants in the biosynthesis of selected metallic nanoparticles and their potential importance. 相似文献
192.
《Intermetallics》2017
The effect of P on the glass forming ability, soft magnetic properties and oxidation behavior of Fe78B13Si9-xPx (x = 0–7) amorphous alloys were investigated. It is found that the proper introduction of P, can effectively improve the glass forming ability and stability of supercooled liquid region. Fe78Si4B13P5 BMG, which exhibits high saturation flux density of 1.56 T, was readily made into rod sample with a diameter of 1.5 mm under air casting atmosphere. P bearing alloys also exhibit excellent soft magnetic properties containing low coercivity of 1.7–2.7 A/m, and high effective permeability of 8200–12,200. Slight oxidation can further improve the coercivity to a lower value of 1.1 A/m and the higher effective permeability to 11,900 for the alloys with P content no more than 3 at. %. Excessive addition of P may deteriorate the glass forming ability, soft magnetic properties and oxidation behavior. Magnetic domain revealing the magnetization process of the amorphous ribbons were characterized to explain the effect of P on magnetic properties and oxidation behavior. 相似文献
193.
Amirkianoosh Kiani Palneet Singh Waraich Krishnan Venkatakrishnan Bo Tan 《Nanoscale research letters》2012,7(1):518
In this work, we have proposed a concept for the generation of three-dimensional (3D) nanostructured metal alloys of immiscible materials induced by megahertz-frequency ultrafast laser pulses. A mixture of two microparticle materials (aluminum and nickel oxide) and nickel oxide microparticles coated onto an aluminum foil have been used in this study. After laser irradiation, three different types of nanostructure composites have been observed: aluminum embedded in nickel nuclei, agglomerated chain of aluminum and nickel nanoparticles, and finally, aluminum nanoparticles grown on nickel microparticles. In comparison with current nanofabrication methods which are used only for one-dimensional nanofabrication, this technique enables us to fabricate 3D nanostructured metal alloys of two or more nanoparticle materials with varied composite concentrations under various predetermined conditions. This technique can lead to promising solutions for the fabrication of 3D nanostructured metal alloys in applications such as fuel-cell energy generation and development of custom-designed, functionally graded biomaterials and biocomposites. 相似文献
194.
195.
Electrical conductivity and supercapacitor properties of polyaniline/chitosan/nickel oxide honeycomb nanocomposite
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this work, a polyaniline honeycomb nanocomposite is synthesized via chemical route and Breath Figure technique and characterized through Fourier Transform Infrared, X‐ray diffraction, thermogravmetric analysis, and morphological analysis (SEM and TEM). The DC, AC conductivities, and Mott's VRH parameters have been measured in the temperature range from 303 to 373 K and frequency range from 20 Hz to 1 MHz. The DC conductivity of the nanocomposite enhanced and AC‐conductivity is attributed to overlapping large polaron tunneling (OLPT) mechanism. The composite is tested for supercapacitor properties. A specific capacitance of 554 F/g and energy density of 76.9 Wh/kg at 1 A/g current density, and high power density of 2.00 kW/kg at 4 A/g indicates more feasibility of the redox process. Electrochemical impedance spectroscopy and cyclic voltammetry reveals that the nanocomposite is an excellent supercapacitor electrode material. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44536. 相似文献
196.
《Intermetallics》2014
It has been suggested that intrinsic ductile versus brittle properties of alloys be connected with bonding characters in some sense while there is no much proof. In this investigation, 27Al isotropic metallic shifts of Al–Li solid solutions were measured by 27Al NMR spectroscopy. Previously observed anomalous elastic properties upon Li alloying were found to be closely related to 27Al metallic shifts which were associated with s electron density of states at the Fermi level on Al sites. This result is relevant for better understanding of electronic origin of solid solution strengthening mechanisms in Al–Li alloys from the point of view of electronic structure. 相似文献
197.
Xiaochao Liu Yuejun Liu Jian Yang Wenzhi Wang Dengwang Lai Long Mao Wei Zheng Jun Yang Xi Chen 《应用聚合物科学杂志》2019,136(21):47504
Polyamide 6–66 (PA6-66)–montmorillonite (MMT)–nanosilica (NS) nanocomposite films were fabricated through a cast film process and then biaxially stretched on a laboratory stretcher. Uniaxial or biaxial stretching induced the elongated conformation of MMT and NS. The b axis of the α crystals and the amorphous phase were revealed to align along the machine direction (MD) after stretching, with the uniaxial orientation playing a more significant role. Furthermore, the crystallinity of PA6-66 stretching increased with the stretching ratio. Uniaxial stretching gave rise to a significantly enhanced tensile strength along the MD, whereas it slightly decreased the mechanical properties along the transverse direction (TD). In contrast, the films subjected to biaxial stretching exhibited more balanced mechanical properties. Uniaxial and biaxial stretching led to decreased transmittance and increased haze in the PA6-66–MMT–NS films; this could have been due to the elongated nanostructure of the two nanofillers, which inhibited the transmission and facilitated the scattering of visible light. The thermal shrinkage of the films increased with increasing stretching ratio, and the biaxially oriented films presented nearly equal shrinkage in the MD and TD. The addition of nanofillers decreased the shrinkage attributed to the mobility inhibition of the polymer chains during heating. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47504. 相似文献
198.
Nylon 6 nanofibers incorporated with molecularly imprinted polymers (MIPs) were successfully fabricated by electrospinning with fiber diameters in the range 80–145 nm. Then, they were used as a new material for the extraction of selected bisphenol A (BPA) in water samples. Field emission scanning electron microscopy images revealed that the nanofibers had a smooth morphology with a good incorporation of MIPs. The Fourier transform infrared and energy-dispersive X-ray spectroscopy results also confirmed the formation of the MIPs in the nanofibers. Furthermore, Raman spectroscopy showed that the crystalline structure of the pristine nylon 6 nanofiber was a kind of α form, and the incorporation of MIPs led to a γ-form structure in the nanofibers; this proved the interactions between nylon 6 and the MIPs. Adsorption studies also confirmed that the adsorption efficiency of BPA onto the molecularly imprinted polymer nanofibers (MIP-NFs; 83.5%) was much greater than that onto nonimprinted polymer nanofibers (NIP-NFs; 36.8%). Also, the imprinting factor was 3.4; this strongly implied the successful formation of molecularly imprinted cavities on the MIP-NFs with a strong affinity to BPA. The maximum adsorption capacity of the MIP-NFs was 103.8 mg/g. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47112. 相似文献
199.
200.
《分离科学与技术》2012,47(11):2559-2581
Abstract Continuous and batch processes of polymer enhanced ultrafiltration for the estimation of binding constants of divalent cadmium, nickel, and zinc ions have been elaborated. Polyethyleneimine was used as a complexation agent. Effect of pH and ionic strength on the binding ability of target metal ions to polyethyleneimine were estimated by continuous mode PEUF system. A mathematical model was developed to estimate apparent complexation constants of metal ions with PEI. The development of this model, which is in good agreement with experimental data, enables to compare the data obtained in both continuous and batch system and correlate the effect of pH and ionic strength with apparent binding constants. 相似文献