全文获取类型
收费全文 | 2690篇 |
免费 | 109篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 84篇 |
综合类 | 4篇 |
化学工业 | 605篇 |
金属工艺 | 85篇 |
机械仪表 | 94篇 |
建筑科学 | 67篇 |
矿业工程 | 2篇 |
能源动力 | 204篇 |
轻工业 | 250篇 |
水利工程 | 30篇 |
石油天然气 | 31篇 |
无线电 | 276篇 |
一般工业技术 | 455篇 |
冶金工业 | 382篇 |
原子能技术 | 16篇 |
自动化技术 | 228篇 |
出版年
2024年 | 5篇 |
2023年 | 35篇 |
2022年 | 55篇 |
2021年 | 116篇 |
2020年 | 78篇 |
2019年 | 76篇 |
2018年 | 113篇 |
2017年 | 88篇 |
2016年 | 97篇 |
2015年 | 68篇 |
2014年 | 89篇 |
2013年 | 249篇 |
2012年 | 173篇 |
2011年 | 164篇 |
2010年 | 118篇 |
2009年 | 108篇 |
2008年 | 96篇 |
2007年 | 79篇 |
2006年 | 75篇 |
2005年 | 54篇 |
2004年 | 48篇 |
2003年 | 57篇 |
2002年 | 45篇 |
2001年 | 45篇 |
2000年 | 48篇 |
1999年 | 34篇 |
1998年 | 120篇 |
1997年 | 82篇 |
1996年 | 65篇 |
1995年 | 53篇 |
1994年 | 33篇 |
1993年 | 33篇 |
1992年 | 7篇 |
1991年 | 19篇 |
1990年 | 15篇 |
1989年 | 14篇 |
1988年 | 24篇 |
1987年 | 23篇 |
1986年 | 16篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 9篇 |
1975年 | 6篇 |
排序方式: 共有2813条查询结果,搜索用时 15 毫秒
91.
Bushra Bashir Abdur Rahman Humera Sabeeh Muhammad Azhar Khan Mohamed F. Aly Aboud Muhammad Farooq Warsi Imran Shakir Philips Olaleye Agboola Muhammad Shahid 《Ceramics International》2019,45(6):6759-6766
Nickel ferrites with high theoretical capacitance value as compared to the other metal oxides have been applied as electrode material for energy storage devices i.e. batteries and supercapacitors. High tendency towards aggregation and less specific surface area make the metal oxides poor candidate for electrochemical applications. Therefore, the improvements in the electrochemical properties of nickel ferrites (NiFe2O4) are required. Here, we report the synthesis of graphene nano-sheets decorated with spherical copper substituted nickel ferrite nanoparticles for supercapacitors electrode fabrication. The copper substituted and unsubstituted NiFe2O4 nanoparticles were prepared via wet chemical co-precipitation route. Reduced graphene oxide (rGO) was prepared via well-known Hummer's method. After structural characterization of both ferrite (Ni1-xCuxFe2O4) nanoparticles and rGO, the ferrite particles were decorated onto the graphene sheets to obtain Ni1-xCuxFe2O4@rGO nanocomposites. The confirmation of preparation of these nanocomposites was confirmed by scanning electron microscopy (SEM). The electrochemical measurements of nanoparticles and their nanocomposites (Ni0.9Cu0.1Fe2O4@rGO) confirmed that the nanocomposites due to highly conductive nature and relatively high surface area showed better capacitive behavior as compared to bare nanoparticles. This enhanced electrochemical energy storage properties of nanocomposites were attributed to the graphene and also supported by electrical (I-V) measurements. The cyclic stability experiments results showed ~65% capacitance retention after 1000 cycles. However this retention was enhanced from 65% to 75% for the copper substituted nanoparticles (Ni0.9Cu0.1Fe2O4) and 65–85% for graphene based composites. All this data suggest that these nanoparticles and their composites can be utilized for supercapacitors electrodes fabrication. 相似文献
92.
The study has focused on electricity generation from organic acid-rich bio-substrate like star fruit (Averrhoa carambola). The sap of star fruit was selected as an electrolyte due to the presence of significant amounts of organic acids such as citric acid and ascorbic acid. To preserve the sap, 2% phenol by volume was used to reduce the growth of microorganisms, and the addition of phenol did not affect the initial pH. It was observed that due to an increase in the electrode surface area, reaction rate and current generation had been amplified. Internal resistance also decreased rapidly because of the large electrode surface area. Furthermore, internal resistance was the significant barrier in electricity generation, which was also successfully controlled by the baffle flow agitation system. Moreover, the baffle flow agitation system reduces the formation of dead zones and increases the total dissolved solids inside the electrochemical cell compartments during operation. 相似文献
93.
Nazish Jahan Saba Aslam Khalil ur Rahman Tuba Fazal Fareeha Anwar Rubab Saher 《Journal of Experimental Nanoscience》2016,11(1):72-80
Nanotechnology is a promising technique to increase the bioavailability of herbal medicines. This paper presents the nanosuspension approach for increasing the aqueous solubility and thereby bioactivity of important herbal extracts. Nanosuspensions of the seeds of three plants extract (Silybum marianum, Elettaria cardamomum and Coriandrum sativum) were prepared by using polyvinyl alcohol (1.5% w/v) as a stabiliser. Prepared nanoparticles were characterised by scanning electron microscope. Activity of nanosuspension formulation was assessed by using four in vitro antioxidant assays. S. marianum, E. cardamomum and C. sativum particle size was observed to fall in range of 446.1 ± 112.6, 456.63 ± 339.2 and 432.1 ± 172.8 nm, respectively, most of the particles were having spherical shape and smooth topology. These synthesised nanoparticles were found to be more effective against quenching free radical than their crude extracts and standards [butylated hydroxyl toluene and ascorbic acid]. C. sativum nanosuspension showed most free radical scavenging potential against 2,2-diphenyl-1-picrylhdrazyl (DPPH) and superoxide free radical scavenging assays (IC50 0.59 ± 0.01 and 0.81 ± 0.11 mg/ml). S. marianum nanosuspension was found to be most effective against DPPH radicals scavenging (IC50 0.34 ± 0.02 mg/ml). It was concluded that nanosuspension of herbal medicines potentiates the antioxidant potential. 相似文献
94.
Modeling the response of Listeria monocytogenes at various storage temperatures in pork with/without electrolyzed water treatment 总被引:1,自引:0,他引:1
Jun Wang S. M. E. Rahman Myoung-Su Park Joong-Hyun Park Deog-Hwan Oh 《Food science and biotechnology》2012,21(6):1549-1555
The objective of this study was to develop a model of the growth of Listeria monocytogenes in pork untreated or treated with low concentration electrolyzed water (LcEW) and strong acid electrolyzed water (SAEW), as a function of temperature. The experimental data obtained under different temperatures (4, 10, 15, 20, 25, and 30°C) were fitted into the modified Gompertz model to generate the growth parameters including specific growth rate (SGR) and lag time (LT) with high coefficients of determination (R2 >0.97). The obtained SGR and LT were employed to develop square root models to evaluate the effects of storage temperature on the growth kinetics of L. monocytogenes in pork. The values of bias factor (0.924–1.009) and accuracy factor (1.105–1.186), which were regarded as acceptable, demonstrated that the obtained models could provide good and reliable predictions and be suitable for the purpose of microbiological risk assessment of L. monocytogenes in pork. 相似文献
95.
Metallurgical and Materials Transactions A - In this work, the growth of conductive AlN thin films by plasma-assisted reactive evaporation at different filament-to-substrate distances was presented... 相似文献
96.
Machine Learning - Covariance estimation for high-dimensional datasets is a fundamental problem in machine learning, and has numerous applications. In these high-dimensional settings the number of... 相似文献
97.
98.
Alaa A. Abdel Rahman Ahmed G. El-Shafei Fatin F. Mahmoud 《International Journal of Mechanics and Materials in Design》2016,12(2):193-209
In the context of integrated nonlinear viscoelastic contact mechanics, a nonlinear finite element model is developed to predict and analyze the quasistatic response of nanoindentation problems of an elastically-layered viscoelastic materials considering the surface elasticity effects. Effects of surface energy are accounted for by employing the Gurtin–Murdoch continuum model for surface elasticity. The linear viscoelastic response is modeled by the Schapery’s creep model with a Prony’s series to express the transient component in the creep compliance. The viscoelastic constitutive equations are cast into a recursive form that needs only the previous time increment rather than the entire strain history. To satisfy the contact constraints exactly, the Lagrange multiplier method is adopted to enforce the contact conditions into the system. The equilibrium indentation configuration is obtained through the Newton–Raphson iterative procedure. The developed model is verified then applied to investigate the quasistatic nanoindentation response of two different indentation problems with different geometry and loading conditions. Results show the significant effects of surface energy and viscoelasticity on the quasistatic nanoindentation response. 相似文献
99.
100.
Abdul Khalib Zahereel Ishwar Ehtiba Farij Omar Ahmad R. Badlishah Salim Naseer Sabri Rahman Mostafijur Li Mingfu 《Multimedia Tools and Applications》2018,77(21):28799-28816
Multimedia Tools and Applications - Adaptive Media Playout (AMP) controls adapt playout rate to prevent buffer outage and to reduce delay in playout. Most AMP techniques use buffer fullness or its... 相似文献