全文获取类型
收费全文 | 1279篇 |
免费 | 95篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 32篇 |
综合类 | 1篇 |
化学工业 | 369篇 |
金属工艺 | 24篇 |
机械仪表 | 41篇 |
建筑科学 | 53篇 |
矿业工程 | 3篇 |
能源动力 | 68篇 |
轻工业 | 141篇 |
水利工程 | 23篇 |
石油天然气 | 22篇 |
无线电 | 120篇 |
一般工业技术 | 230篇 |
冶金工业 | 54篇 |
原子能技术 | 7篇 |
自动化技术 | 195篇 |
出版年
2024年 | 4篇 |
2023年 | 19篇 |
2022年 | 49篇 |
2021年 | 75篇 |
2020年 | 68篇 |
2019年 | 53篇 |
2018年 | 83篇 |
2017年 | 66篇 |
2016年 | 75篇 |
2015年 | 65篇 |
2014年 | 77篇 |
2013年 | 165篇 |
2012年 | 82篇 |
2011年 | 101篇 |
2010年 | 64篇 |
2009年 | 41篇 |
2008年 | 42篇 |
2007年 | 28篇 |
2006年 | 16篇 |
2005年 | 33篇 |
2004年 | 23篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有1383条查询结果,搜索用时 15 毫秒
981.
Ruma Perveen Abu Nasar Abdullah M. Asiri A.K. Mishra 《International Journal of Hydrogen Energy》2018,43(32):15144-15154
This study reports the synthesis of a nanocomposite comprised of graphene (G) supported manganese dioxide (MnO2) incorporated into the network of polythioaniline (MnO2-G/PTA). The hybrid composite was applied as an electrode material for the development of a bioanode. The bioanode was fabricated by the electrochemical entrapment of ferritin (Frt) as mediator and glucose oxidase (GOx) enzyme in the matrix of the as-synthesized MnO2-G/PTA deposited on glassy carbon electrode (GCE) surface. The structural features and electrochemical behaviour of the modified electrodes were investigated by Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The results unfolded that the hybrid electroactive support (MnO2-G/PTA) employed for the immobilization of the enzyme (GOx) established an appropriate electrical cabling between the redox enzyme (GOx) and the electrode surface with the assistance provided by the biocompatible mediator (Frt) working to enhance the electrical signals. The developed GCE/MnO2-G/PTA/Frt/GOx bioanode attained a maximum current density of 3.68 mAcm?2 at 35 mM glucose concentration at a scan rate of 100 mVs?1. Thus, the MnO2-G/PTA/Frt/GOx modified electrode possesses high potential and good biocompatibility for bio-electricity production from glucose. 相似文献
982.
Inhibition of Shigella sonnei and Shigella flexneri in Hummus Using Citric Acid and Garlic Extract 下载免费PDF全文
Amin N. Olaimat Murad A. Al‐Holy Mahmoud H. Abu‐Ghoush Tareq M. Osaili Anas A. Al‐Nabulsi Barbara A. Rasco 《Journal of food science》2017,82(8):1908-1915
Hummus (chickpea dip) is a ready‐to‐eat product that may pose a significant risk to human if pathogens are present. Several organisms including Shigella spp. have been isolated from hummus. However, studies on the survival and inhibition of Shigella spp. in food are scarce. This study investigated the growth pattern of Sh. sonnei and Sh. flexneri in hummus at different temperatures (4, 10, and 24 °C). Additionally, the inhibitory activity of different concentrations of citric acid (CA) (0.5%, 1.0%, and 2.0%) and garlic extract (GE) (1.0%, 2.0%, and 3.0%) against Sh. sonnei and Sh. flexneri inoculated into hummus and stored at 4 and 10 °C was investigated. Both Shigella spp. survived well at 4 °C, while both grew to >7.0 log10 after 4 d at 10 °C or 1 d at 24 °C. At 4 °C, CA at 0.5% and 1.0% resulted in a slight reduction in the count (approximately 1.0 log10); a complete elimination of Sh. sonnei was attained by using 2.0% CA. However, approximately 3.0 log10 reduction in Sh. sonnei was obtained at 10 °C. For Sh. flexneri, CA at 0.5% and 1.0% resulted in a bacteriostatic inhibition. GE at 1.0% and 2.0% resulted in approximately 1.0 to 2.0 log10 reduction in Sh. sonnei count at 4 °C, while at 3.0% GE, approximately 4.0 and 3.0 log10 reductions were obtained at 4 and 10 °C, respectively. In comparison, the 2.0% and 3.0% GE resulted in a bacteriostatic effect against Sh. flexneri at 4 and 10 °C. 相似文献
983.
Effect of Processing Methods on Alkaloids,Phytate, Phenolics,Antioxidants Activity and Minerals of Newly Developed Lupin (Lupinus albus L.) Cultivar 下载免费PDF全文
984.
The objective of this work is focused in measuring the level of naturally occurring radionuclides in compact fluorescent lamps commonly used in Egypt. The activity concentration of radionuclides in the (238)U and (232)Th decay chains and from (40)K were determined through gamma-ray spectrometry measurements using high-purity germanium in a low-background configuration. It was found that the activity concentrations ranged from 45 to 198 Bq kg(-1) for (238)U, from 30 to 191 Bqkg(-1) for (232)Th and from 419 to 935 Bq kg(-1) for (40)K. 相似文献
985.
Mohammad Yazdanbakhsh Iman Khosravi Mahboobeh-Sadat Mashhoori Mohammad Rahimizadeh Ali Shiri Mehdi Bakavoli 《Materials Research Bulletin》2012,47(2):413-418
The nano-sized Co2CrO4 spinel was produced for the first time by thermal decomposition of Cr–Co gel prepared by sol–gel method. It was shown that well-crystallized spinel structure is formed after calcination at 450 °C. The usual characterizations were performed and the results showed the particle size of the prepared spinel is 9 nm. Moreover, the prepared nano-sized Co2CrO4 spinel was applied in a simple, efficient and recyclable method for selective oxidation of sulfides to their corresponding sulfoxides with aqueous hydrogen peroxide in tert-butanol. 相似文献
986.
Md. Saiful Islam Sinin Hamdan Zainal Abidin Talib Abu Saleh Ahmed Md. Rezaur Rahman 《Composites Science and Technology》2012
In this study, wood polymer nanocomposites (WPNCS) were manufactured from five Malaysian tropical wood species by vacuum-impregnation attended by in situ polymerization using phenol–formaldehyde resin and montmorillomite nanoclay. Percentage weight gain and density of wood polymer nanocomposites depended on wood species. Thermo-mechanical properties of wood samples were investigated by the dynamic mechanical thermal analysis (DMTA) over the temperature range of −100 °C to 200 °C. The intrinsic properties of the components, morphology of the system and the nature of interface between the phases were also determined through DMTA test. Storage modulus (E′) of WPNC samples exhibited significant improvement over the temperature range, in both glassy region and rubbery plateau in relation to their corresponding raw wood samples and wood polymer composites (WPCs). Furthermore, damping (loss tan δ) peaks of all wood species were lowered by PF-Nanoclay system treatment, an indication of improved surface interphase of wood. Dynamic Young’s modulus (Ed) of wood was also calculated using free–free vibration testing. A significant increment was obtained for the PF-Nanoclay impregnated WPNC samples. 相似文献
987.
Azman Hassan Arshad Adam Salema Farid Nasir Ani Aznizam Abu Bakar 《Polymer Composites》2010,31(12):2079-2101
Natural fiber‐reinforced polymer composite materials have emerged in a wide spectrum of area of the polymer science. The composite produced from these types of materials are low density, low cost, comparable specific properties, and most importantly they are environmental friendly. The composite materials produced from oil palm fibers and commercially available polymers have offered some specific properties that can be comparable to conventional synthetic fiber composite materials. However, these properties are greatly dependent on the compatibility of oil palm fibers and matrix phase with moisture absorption as one of the critical issues that becomes the drawbacks of the oil palm fiber polymer composite materials. Apparently, it greatly affects the physical as well as mechanical properties of the composite materials. The present review reports the work on oil palm empty fruit bunch (OPEFB) fiber‐reinforced polymer composites with some interest on the OPEFB physical structure, and chemical compositions. Finally, the incorporation of OPEFB into polymeric materials leads to several interesting consequences on the water absorption characteristics and the mechanical properties, which have been reviewed. POLYM. COMPOS., 31:2079–2101, 2010. © 2010 Society of Plastics Engineers 相似文献
988.
Brad R. Cohn Bonnie N. Joe Shoujun Zhao John Kornak Vickie Y. Zhang Rahwa Iman John Kurhanewicz Kiarash Vahidi Jingwei Yu Aaron B. Caughey Mark G. Swanson 《Magma (New York, N.Y.)》2009,22(6):343-352
Object
To establish and compare normative metabolite concentrations in 2nd and 3rd trimester human amniotic fluid samples in an effort to reveal metabolic biomarkers of fetal health and development.Materials and methods
Twenty-one metabolite concentrations were compared between 2nd (15–27 weeks gestation, N = 23) and 3rd (29–39 weeks gestation, N = 27) trimester amniotic fluid samples using 1H high resolution magic angle spinning (HR-MAS) spectroscopy. Data were acquired using the electronic reference to access in vivo concentrations method and quantified using a modified semi-parametric quantum estimation algorithm modified for high-resolution ex vivo data.Results
Sixteen of 21 metabolite concentrations differed significantly between 2nd and 3rd trimester groups. Betaine (0.00846±0.00206 mmol/kg vs. 0.0133±0.0058 mmol/kg, P < 0.002) and creatinine (0.0124±0.0058 mmol/kg vs. 0.247±0.011 mmol/kg, P < 0.001) concentrations increased significantly, while glucose (5.96±1.66 mmol/kg vs. 2.41±1.69 mmol/kg, P < 0.001), citrate (0.740±0.217 mmol/kg vs. 0.399±0.137 mmol/kg, P < 0.001), pyruvate (0.0659±0.0103 mmol/kg vs. 0.0299±0.286 mmol/kg, P < 0.001), and numerous amino acid (e.g. alanine, glutamate, isoleucine, leucine, lysine, and valine) concentrations decreased significantly with advancing gestation. A stepwise multiple linear regression model applied to 50 samples showed that gestational age can be accurately predicted using combinations of alanine, glucose and creatinine concentrations.Conclusion
These results provide key normative data for 2nd and 3rd trimester amniotic fluid metabolite concentrations and provide the foundation for future development of magnetic resonance spectroscopy (MRS) biomarkers to evaluate fetal health and development. 相似文献989.
Mustafa Kamal Abu Bakr El-Bediwi Tarek El-Ashram 《Journal of Materials Science: Materials in Electronics》2004,15(4):211-217
A group of rapidly solidified Sn–Cd alloys has been prepared by a melt-spinning technique. X-ray diffraction, microstructure, and differential thermal analysis have been carried out. Youngs modulus and internal friction have been measured, and the temperature dependence of resistivity has been evaluated. The results show a modification in both the microstructure and decomposition behavior. Also, an interesting connection between Youngs modulus and the axial ratio (c/a) of the unit cell of the -Sn was found in which Youngs modulus increases by increasing the axial ratio (c/a). It was found also that the internal friction increases on increasing the Cd concentration. 相似文献
990.
M. A. Hader M. A. Al-Nimr B. A. Abu Nabah 《International Journal of Thermophysics》2002,23(6):1669-1680
In the present work, the thermal behavior of a thin slab, under the effect of a fluctuating volumetric thermal disturbance described by the dual-phase-lag heat conduction model is investigated. It is found that the use of the dual-phase-lag heat conduction model is essential at large frequencies of the volumetric disturbance. It is found that the hyperbolic wave model deviates from the diffusion model when
and the dual-phase-lag model deviates from the diffusion model when
. where
is the angular velocity of the fluctuating wall temperature,
is the phase-lag in the heat flux vector and
is the phase-lag in the temperature gradient vector. 相似文献