全文获取类型
收费全文 | 557篇 |
免费 | 64篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 7篇 |
综合类 | 21篇 |
化学工业 | 251篇 |
金属工艺 | 38篇 |
机械仪表 | 4篇 |
建筑科学 | 7篇 |
矿业工程 | 1篇 |
能源动力 | 68篇 |
轻工业 | 2篇 |
水利工程 | 1篇 |
石油天然气 | 52篇 |
无线电 | 39篇 |
一般工业技术 | 122篇 |
冶金工业 | 10篇 |
原子能技术 | 1篇 |
自动化技术 | 7篇 |
出版年
2024年 | 6篇 |
2023年 | 38篇 |
2022年 | 24篇 |
2021年 | 21篇 |
2020年 | 38篇 |
2019年 | 29篇 |
2018年 | 20篇 |
2017年 | 29篇 |
2016年 | 28篇 |
2015年 | 17篇 |
2014年 | 37篇 |
2013年 | 35篇 |
2012年 | 29篇 |
2011年 | 21篇 |
2010年 | 20篇 |
2009年 | 25篇 |
2008年 | 14篇 |
2007年 | 22篇 |
2006年 | 26篇 |
2005年 | 20篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 13篇 |
1999年 | 11篇 |
1998年 | 11篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有631条查询结果,搜索用时 31 毫秒
1.
《International Journal of Hydrogen Energy》2020,45(38):19313-19323
Fe–Co/Al2O3 catalysts were developed and tested in the catalytic decomposition of methane (CDM) for the synthesis of multi-wall carbon nanotubes (MWCNT) and the CO2-free hydrogen production. While Fe (54.5–66.7 mol.%) is the main active phase for the carbon formation on the catalyst, Co acts as dopant aiming to improve its overall catalytic behaviour. Catalysts with Co contents of up to 18.2 M% showed the presence of α-Fe and Fe–Co crystallites with different size and lattice parameter. Fe1-xCox alloy with bcc crystal system was identified only for Co contents of 14.0% and above, and presented a lattice constant lower than α-Fe, which would modify the carbon diffusion of the metal particle during the MWCNT growth. Co inhibited the Fe3C formation during CDM resulting in higher carbon formations and longer activity times. This phase, shown in undoped catalysts, favored the presence of bamboo-type carbon nanotubes. 相似文献
2.
《International Journal of Hydrogen Energy》2020,45(43):23056-23068
A series of monometallic and bimetallic palladium gold catalyst were prepared and studied for the formic acid dehydrogenation reaction. Different Pd/Au compositions were employed (PdxAu100-x, where x = 25; 50 and 75) and their impact on alloy structure, particle size and dispersion was evaluated. Active phase composition and reaction parameters such as temperature, formic acid concentration or formate/formic acid ratio were adjusted to obtain active and selective catalyst for hydrogen production. An important particle size effect was observed and related to Pd/Au composition for all bimetallic catalysts. 相似文献
3.
《International Journal of Hydrogen Energy》2020,45(16):9624-9634
Decomposition of formic acid biomass to generate hydrogen is vital for coping with fossil energy depletion, environmental pollution, and developing clean, efficient, safe, and sustainable modern energy system. In this study, a PdAu/C−C bimetallic catalyst was prepared by the co-impregnation method followed by an atmospheric pressure (AP) cold plasma treatment to synthesize PdAu/C−P catalysts. The resulting PdAu/C−P showed excellent catalytic activity for the formic acid dehydrogenation (FAD) reaction. The total volume of H2 and CO2 released from the FAD reaction was about 375 mL after 4 h at 50 °C, and the initial turnover frequency (TOFinitial) was 808.6 h−1. We used X−ray diffractometry (XRD), temperature programmed reduction (TPR) and high-resolution transmission electron microscopy (HRTEM) to show that plasma can effectively promote the redispersion of Pd−Au particles on the surface of the support. The average particle size of PdAu/C−P (3.5 ± 1.5 nm) was less than PdAu/C−C (4.4 ± 1.9 nm) and uniformly distributed. X-ray photoelectron spectroscopy (XPS), TPR, and HRTEM showed that PdAu/C−P has a higher degree of alloying. In addition, the strong electric field in the plasma facilitated more metal sites located on the outer surface of the support in PdAu/C−P, and the atomic ratio of M/C (M = Pd and Au) (0.0134) was much larger than that of PdAu/C−C (0.0060). The apparent activation energy (Ea) of PdAu/C−P for the FAD reaction was only 27.25 kJ mol−1, and it had much higher activity and stability than the commercial Pd/C (Sigma−Aldrich). The total volume of H2 and CO2 produced over the PdAu/C−P for three cycles was 1.33, 5.87, and 8.56 times that of commercial Pd/C. Overall, the cold plasma enhanced the degree of alloying, promoted the redispersion of agglomerated particles, and regulated the surface enrichment of the active metal components. This is of great significance for guiding the preparation of high−performance multi-metal catalysts by cold plasma. 相似文献
4.
《International Journal of Hydrogen Energy》2020,45(1):1018-1029
Mixed Pd–Au bimetallic nanoparticles embedded nitrogen doped graphene composites (PdAu/NG180) are explored for efficient electrocatalytic oxidation of methanol. A simple hydrothermal one-pot polyol method, involving simultaneous reduction of both Pd and Au, is utilized for the synthesis of Pd20-xAux/NG180 (x wt % = 0, 5, 10 and 15). This method is of multiple advantages such as inexpensiveness, reagent-free and environment-friendly being surfactant free. The morphology, crystal structure and chemical composition of NG180, Pd/NG180 and Pd20-xAux/NG180 catalysts are analyzed by XRD, FESEM-EDX, TEM, XPS and Raman spectroscopy methods. Electrocatalytic activities of PdAu/NG180 nanocomposites toward methanol oxidation reaction (MOR) in alkaline media are investigated by cyclic voltammetry, chronoamperometry and CO stripping measurements. Pd20-xAux/NG180 exhibited an increase in the electroactive surface area of Pd to twice by the coexistence of Au. In cyclic voltammetry studies, Pd10Au10/NG180 catalyst exhibits highest peak current density for MOR and is 1.5 times highly efficient compared to Pd20/NG180 with an enhanced shift in the onset potential by 140 mV to lower overpotentials. Besides, Pd10Au10/NG180 catalyst exhibited enhanced electroactive surface area and long-time durability in comparison to Pd20/NG180 catalyst. The steady state current density for MOR observed with Pd10Au10/NG180 at the end of 4000 s (98 mA mg−1Pd) is higher than those observed with all the other catalysts at the end of mere 1000 s alone (97, 61, and 32 mA mg−1Pd). The promising high electrocatalytic activity of Pd10Au10/NG180 is well corroborated from CO stripping experiments that the specific adsorption of CO onto Pd10Au10/NG180 (0.71 C m−2) is merely half to that observed onto Pd20/NG180 (1.49 C m−2). 相似文献
5.
Dr. Dandan Li Qianqian Guo Liming Ding Wei Zhang Lu Cheng Yanqiu Wang Dr. Zhuobin Xu Dr. Huihui Wang Prof. Lizeng Gao 《Chembiochem : a European journal of chemical biology》2020,21(18):2620-2627
Peroxidase-mimicking nanozymes that can generate toxic hydroxyl radicals (.OH) hold great promise as antibacterial alternatives. However, most of them display optimal performance under strongly acidic conditions (pH 3–4), and are thus not feasible for many medical uses, including burn infections with a wound pH close to neutral. Herein, we report a copper-based nanozyme (CuCo2S4) that exhibits intrinsic peroxidase-like activity and can convert H2O2 into .OH at neutral pH. In particular, bimetallic CuCo2S4 nanoparticles (NPs) exhibited enhanced peroxidase-like activity and antibacterial capacity, superior to that of the corresponding monometallic CuS and CoS NPs. The CuCo2S4 nanozymes possessed excellent ability to kill various bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, this CuCo2S4 nanozymes could effectively disrupt MRSA biofilms in vitro and accelerate MRSA-infected burn healing in vivo. This work provides a new peroxidase mimic to combat bacteria in neutral pH milieu and this CuCo2S4 nanozyme could be a promising antibacterial agent for the treatment of burn infections. 相似文献
6.
Wenjuan Sun Zhongyuan Fu Huanxian Shi Chenyang Jin Enzhou Liu Xiaoli Zhang Jun Fan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2020,95(12):3117-3125
Copper-nickel phosphides/ graphite-like phase carbon nitride (Cu3P-Ni2P/g-C3N4) composites were obtained through a facile one-pot in situ solvothermal approach. The coexistence of Cu3P and Ni2P plays an important role in enhancing the catalytic activity of g-C3N4. The 7 wt% Cu3P-Ni2P/g-C3N4 bimetallic phosphide photocatalyst demonstrates the best photocatalytic hydrogen (H2) evolution rate of 6529.8 μmol g−1 h−1, which is 80.7-fold higher than that of g-C3N4. The apparent quantum yield (AQE) was determined to be 18.5% at 400 nm over the 7% Cu3P-Ni2P/g-C3N4. This in situ growth strategy produced intimate contact interfaces, leading to a significantly promoted separation of charge carriers, and hence strengthened the photocatalytic H2 production. Moreover, the coexistence of Cu3P and Ni2P reduced the overpotential of H2 during the evolution process, further benefiting H2 production. Finally, the photocatalytic enhancement mechanism was proposed and verified by fluorescence and electrochemical analysis. This work provides a low-cost strategy to synthesize nonprecious bimetallic phosphides/carbon nitride photocatalyst with outstanding H2 production activity. © 2020 Society of Chemical Industry 相似文献
7.
Abdul Haleem Zeeshan Haider Rafi u Shan Ahmad Uzabakiriho Pierre Claver Afzal Shah Gang Zhao Wei-Dong He 《国际能源研究杂志》2020,44(11):8442-8454
There have been tremendous efforts made to investigate various materials to enhance the electrical performance of triboelectric nanogenerators (TENGs) but there is still demand for some techniques to further enhance the performance of tribomaterials. Therefore, we fabricated a bimetallic hybrid cryogel via cheap and facile UV-radiation as well as in situ reduction method. Fabricated TENG device made up of porous hybrid bimetallic cryogel film containing silver and gold nanoparticles as tribopositive material and poly dimethyl siloxane (PDMS) as a tribonegative layer with dimension of 1 × 2 cm2 has the ability to produced output voltage of 262.14 V with current density of 27.52 mA/m2 and 7.44 W/m2 peak power density, which was sufficient to light up more than 120 white light emitting-diodes (LEDs). Porous and rough structure, interaction of nanoparticles was the reason behind the performance enhancement of tribopositive material. Thus, this study introduces a very stable and easily synthesized bimetallic hybrid cryogel as a tribopositive material to enhance the performance of tribomaterials to design high performance TENG devices. 相似文献
8.
Abolfazl Gharibi Kharaji Ahmad Shariati 《中国炼油与石油化工》2016,18(1):51-58
The performance of the two newly developed bimetallic catalysts based on the precursor, Mo/Al_2O_3, was compared for reverse water gas shift(RWGS) reaction. The structures of the precursor and the catalysts were studied using X-ray diffraction(XRD), Brunauer–Emmett–Teller(BET) analysis, inductively coupled plasma-atomic emission spectrometry(ICP-AES), CO chemisorption, temperature programmed reduction of hydrogen(H_2-TPR) and scanning electron microscopy(SEM) techniques. The activity of Fe-Mo and Co-Mo catalysts was compared in a fixed bed reactor at different temperatures. It is shown that the Co-Mo catalyst has higher CO_2 conversion at all temperature level. The time-on-stream(TOS) analysis of the activity of catalysts for the RWGS reaction was carried out over a continuous period of 60h for both catalysts. The Fe-Mo/Al_2O_3 catalyst exhibits good stability within a period of 60h, however, the Co-Mo/Al_2O_3 is gradually deactivated after 50h of reaction time. Existence of(Fe_2(MoO4_))_3 phase in Fe-Mo/Al_2O_3 catalyst makes this catalyst more stable for RWGS reaction. 相似文献
9.
Density functional theory has been performed to systematically study the interactions between RunPt13-n (n = 4, 7 and 9) clusters and [BMIM]+ based ionic liquids. Ionic liquids [BMIM][Br], [BMIM][BF4], [BMIM][PF6], [BMIM][CF3SO3], and [BMIM][NTf2] have different effects on the stability of Ru7Pt6. Ionic liquids with median size anions of PF6− and CF3SO3− can better improve the stability of Ru7Pt6 than those with the small anions of Br− and BF4− and large anion of NTf2−. Based on negative relaxation energies, the stabilities of Ru4Pt9, Ru7Pt6, and Ru9Pt4 are all enhanced after interacting with [BMIM][CF3SO3]. The stability enhanced degree is in agreement with the interaction strength. For Ru7Pt6–n{[BMIM][CF3SO3]} (n = 1, 2, 3, 4), the interaction between ionic liquid and cluster plays the primary role in stabilizing the cluster in Ru7Pt6–[BMIM][CF3SO3]. With the increase of the number of [BMIM][CF3SO3], the role of the interaction in stabilizing the cluster is getting weaker, while the role of steric protection is getting more important. 相似文献
10.