全文获取类型
收费全文 | 777篇 |
免费 | 66篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 21篇 |
综合类 | 1篇 |
化学工业 | 280篇 |
金属工艺 | 21篇 |
机械仪表 | 18篇 |
建筑科学 | 22篇 |
能源动力 | 35篇 |
轻工业 | 64篇 |
水利工程 | 8篇 |
石油天然气 | 17篇 |
无线电 | 97篇 |
一般工业技术 | 142篇 |
冶金工业 | 42篇 |
原子能技术 | 3篇 |
自动化技术 | 77篇 |
出版年
2023年 | 13篇 |
2022年 | 18篇 |
2021年 | 37篇 |
2020年 | 25篇 |
2019年 | 42篇 |
2018年 | 65篇 |
2017年 | 46篇 |
2016年 | 33篇 |
2015年 | 32篇 |
2014年 | 43篇 |
2013年 | 59篇 |
2012年 | 50篇 |
2011年 | 53篇 |
2010年 | 44篇 |
2009年 | 28篇 |
2008年 | 24篇 |
2007年 | 17篇 |
2006年 | 15篇 |
2005年 | 15篇 |
2004年 | 18篇 |
2003年 | 19篇 |
2002年 | 18篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 17篇 |
1997年 | 13篇 |
1996年 | 16篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1969年 | 1篇 |
排序方式: 共有848条查询结果,搜索用时 15 毫秒
1.
Enas Taha Sayed Hussain Alawadhi A.G. Olabi Aisha Jamal Menna Salah Almahdi Juiaria Khalid Mohammad Ali Abdelkareem 《International Journal of Hydrogen Energy》2021,46(8):5975-5983
Microbial fuel cell (MFC) is a promising technology for simultaneous wastewater treatment and energy harvesting. The properties of the anode material play a critical role in the performance of the MFC. In this study, graphene oxide was prepared by a modified hummer's method. A thin layer of graphene oxide was incorporated on the carbon brush using an electrophoretic technique. The deoxygenated graphene oxide formed on the surface of the carbon brush (RGO-CB) was investigated as a bio-anode in MFC operated with real wastewater. The performance of the MFC using the RGO-CB was compared with that using plain carbon brush anode (PCB). Results showed that electrophoretic deposition of graphene oxide on the surface of carbon brush significantly enhanced the performance of the MFC, where the power density increased more than 10 times (from 33 mWm?2 to 381 mWm?2). Although the COD removal was nearly similar for the two MFCs, i.e., with PCB and RGO-CB; the columbic efficiency significantly increased in the case of RGO-CB anode. The improved performance in the case of the modified electrode was related to the role of the graphene in improving the electron transfer from the microorganism to the anode surface, as confirmed from the electrochemical impedance spectroscopy measurements. 相似文献
2.
3.
4.
Multiple-access interference (MAI) and multipath fading are two of the most significant factors limiting the capacity and performance of direct-sequence code-division multiple-access (DS-CDMA) systems. In this paper, synchronous multiuser receivers that combine antenna diversity, RAKE reception, and a multipath decorrelator for MAI cancellation are analyzed in a Nakagami faded environment using a maximal ratio combiner or a selection combiner. A coherent binary phase-shift keying employing DS-CDMA is considered. Arbitrary branch correlation is also considered for any diversity order in the case of identical severity fading on the branches. 相似文献
5.
A different newly designed cationic exchange polymer membrane and anionic exchange polymer membrane were introduced, and also the transport properties of these polymeric membranes were investigated in this study. The transport properties of these polymer membranes in contact with ferrocene redox derivatives were estimated by using electrochemical techniques such as cyclicvoltammetry, chronopotentiometry, and chronoamperometry techniques, respectively. The used ferrocene redox substances, which have different functional groups, were (Ferrocenylmethyl) trimethylamonium iodide, FcMA, Ferrocenedimethanol, FcDM, and Ferrocene carboxylic acid, FcCA. It indicated that the performance of a membrane depended on the content of polymer gel, anionic exchange polymer site (20 wt % and 50 wt %) or cationic polymer exchange site (20 wt % and 50 wt %), and the efficiency of the functional groups of cationic and anionic exchange polymer site as well. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
6.
A. Mounir EL Sayed A. Yamauchi N. A. Darwish A. A. Abd EL‐Mageed S. F. Halim 《应用聚合物科学杂志》2008,109(5):2988-2993
The charged mosaic polymer membrane (CMM) without reinforcement and the composite charged mosaic polymer membrane (CCMM) with reinforcement were investigated in terms of salt and water transport (permeability). The composite charged mosaic polymer membrane (CCMM) with reinforcement showed a unique transport behavior such as preferential material transport Lp and ω. Water permeability coefficient, Lp and salt permeability coefficient, ω were estimated by taking account of active layer thickness of composite polymer gel. The Lp and ω values of CCMM with reinforcement were larger than those of CMM without reinforcement. On the other hand, the reflection coefficient of CCMM, σ, showed negative value, which suggested preferential material transport to solvent transport. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
7.
Radiation polymerization of acrylonitrile in a viscous system with styrene was performed at ambient temperature by using γ‐rays. It is found that the overall rate of polymerization was accelerated after critical conversion due to the gel effect. As the molar fraction of styrene in monomer feed (fSt) is increased, both the total polymer conversion and molar fraction of acrylonitrile in the copolymer feed (FAN) were decreased. The monomer reactivity ratios for acrylonitrile and styerne were determined to be r1 (AN) = 0.25 and r2 (St) = 2.0, respectively. The copolymers obtained were characterized by Fourier transformed infrared spectra (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), 1H‐NMR, and pyrolysis mass spectrometry (PMS). It was found that the slight addition of styrene to acrylonitrile strongly changes crystallinity, morphology, and thermal decomposition of the resulting polymer. 1H‐NMR measurment of AN/St copolymer showed the appearance of aromatic proton signals and shifted the resonance of the methylene proton to lower chemical shifts. The mass spectra of AN/St copolymers showed fragments of pyrolysates corresponding to oligonitriles with styrene end groups. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 268–275, 2002; DOI 10.1002/app.10324 相似文献
8.
J Baulieux M Adham E Oussoultzoglou E De la Roche N Berthoux O Bourdeix C Ducerf 《Canadian Metallurgical Quarterly》1998,123(5):438-444
Collagenase-1 (C1) is the predominant matrix metalloproteinase present in newly formed microvessels and serves as a marker of neovascularization. The expression of the oncofetal fragment of fibronectin (Fn-f) was found to be increased during angiogenesis. In the present study, we investigated the relationship between the expression of collagenase-1 and the oncofetal fragment of fibronectin in newly formed microvessels as markers of tumor angiogenesis. In aggressive skin tumors (i.e., morpheaform and recurrent basal cell carcinomas) and squamous cell carcinomas, neovascularization was associated with a marked increase in the number of C1-positive and Fn-f-positive microvessels. At the beginning of elongation, microvessels begin to produce C1 but lose their ability to express type IV collagen and FVIII-related antigen. Later, this endothelium produces both Fn-f and C1. As maturation of microvessels occurs, C1-containing endothelium fails to express Fn-f but begins to produce a type IV collagen-containing basement membrane and FVIII-related antigen. These studies show that there is a selective expression of both Fn-f and collagenase by immature endothelial cells. C1 production begins at early stages of blood vessel formation and continues throughout angiogenesis. In contrast, Fn-f expression is limited to later stages of vasculogenesis, indicating that these proteins are reliable markers of angiogenesis. 相似文献
9.
10.
Although leather has a number of desirable properties such as thermal stability and fire retardancey, in addition to high toughness, it has a few drawbacks such as weight, high water absorption, poor soil and rot resistance, and nonuniformity. If these defects are overcome, leather's usefulness would be further enhanced and its competitive position with respect to synthetics would increase. This study reports the physical and mechanical properties of buffalo leather after chemical graft copolymerization with ethyl acrylate, butyl acrylate, and 2‐ethyl hexyl acrylate using benzoyl peroxide as an initiator. The optimum conditions for grafting (e.g., monomer and initiator concentrations, temperature and time of grafting, and solvent leather ratio) were extensively investigated. The study achieved outstanding properties for buffalo leather in reduction of water uptake after grafting, especially on using 2‐ethyl hexyl acrylate and butyl acrylate monomers. FT‐IR and solid 13C‐NMR for leather before and after grafting confirmed the grafting process.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1478–1483, 2003 相似文献