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11.
《International Journal of Hydrogen Energy》2022,47(21):11116-11127
An important difficulty associated with alkaline water electrolysis is the rise in anode overpotential attributable to bubble coverage of the electrode surface. For this study, a system with a high-speed video camera was developed, achieving in-situ observation of bubble generation on an electrode surface, monitoring an area of 1.02 mm2 at 6000 frames per second. The relation between polarization curve (current density up to 3.0 A cm?2) and oxygen bubble generation behavior on nickel electrodes having cylindrical wires and rectangular wires of different sizes (100–300 μm) was clarified. The generated bubbles slide upward, contacting the electrode surface and detaching at the top edge. Observations indicate that small electrodes have short bubble residence time and thin bubble covering layer on the electrode. As a result, the small electrode diameter contributes to smaller overpotential at high current density. 相似文献
12.
《Advanced Powder Technology》2022,33(1):103371
Black phosphorus (BP), as a new 2D material, is normally synthesized by a high-pressure and high-temperature (HPHT) method from white and red phosphorus, which severely hinders the further development of BP for any potential applications and leads to search for other potential applications of BP with big challenge. Herein, we develop a facile and efficient Thermal-Vaporization-Transformation (TVT) approach to prepare a highly active BP directly grown on carbon paper as the electrode for Oxygen evolution reaction (OER), showing a low onset potential of 1.45 V versus RHE. Simultaneously, the current density of BP-CP illustrates the excellent electro-catalysis stability only decreases by 3.4% after continuous operation for 10000 s. Meanwhile, the density functional theory (DFT) calculations further illustrates the P-doped carbon layer in the upper side of BP layer is actually responsible for its enhanced OER property, and the adjacent carbon atoms of the embedded P atoms are actually the active sites due to the induced local change distribution by intramolecular change transfer. Considering the facile, but efficient and scalable, TVT approach can directly synthesize BP-CP with excellent OER performance, which is promising for BP electrocatalysts used for OER in metal-air batteries, fuel cells, water-splitting devices, even other key renewable energy. 相似文献
13.
《International Journal of Hydrogen Energy》2022,47(30):14053-14062
Nickel-based catalysts have attracted tremendous attention as alternatives to precious metal-based catalysts for electrocatalytic hydrogen evolution reaction (HER) in virtue of their conspicuous advantages such as abundant reserves and high electrochemical activity. Nevertheless, a great challenge for Ni-based electrocatalyst is that nickel sites possess too strong adsorption for key intermediates H1, which severely suppresses the hydrogen-production activities. Herein, we report a hierarchical architecture Cu/Ni/Ni(OH)2 consisting of dual interfaces as a high-efficient electrocatalyst for HER. The Cu nanowire backbone could provide geometric spaces for loading plenty of Ni sites and the formed Ni/Cu interface could effectively weakened the adsorption intensity of H1 intermediates on the catalyst surface. Moreover, the H1 adsorption could be further controlled to appropriate states by in-situ formed Ni(OH)2/Ni interface, which simultaneously promotes water adsorption and activation, thus both Heyrovsky and Volmer steps in HER could be obviously accelerated. Experimental and theoretical results confirm that this interface structure can promote water dissociation and optimize H1 adsorption. Consequently, the Cu/Ni/Ni(OH)2 electrocatalyst exhibits a low overpotential of 20 mV at 10 mA cm?2 and an ultralow Tafel slope of 30 mV dec?1 in 1.0 M KOH, surpassing those of reported transition-metal-based electrocatalysts and even the prevailing commercial Pt/C. 相似文献
14.
《International Journal of Hydrogen Energy》2022,47(34):15189-15197
Oxygen evolution reaction (OER) is a key process involved in many energy-related conversion systems. An ideal OER electrocatalyst should possess rich active sites and optimal binding strength with oxygen-containing intermediates. Although numerous endeavors have been devoted to the modification and optimization of transition-metal-based OER electrocatalysts, they are still operated with sluggish kinetics. Herein, an ion-exchange approach is proposed to realize the structure engineering of amorphous P–CoS hollow nanomaterials by utilizing the ZIF-67 nanocubes as the precursors. The precise structure control of the amorphous hollow nanostructure contributes to the large exposure of surface active sites. Moreover, the introduction of phosphorus greatly modifies the electronic structure of CoS2, which is thus favorable for optimizing the binding energies of oxygenated species. Furthermore, the incorporation of phosphorus may also induce the formation of surface defects to regulate the local electronic structure and surface environment. As a result of this, such P–CoS hollow nanocatalysts display remarkable electrocatalytic activity and durability towards OER, which require an overpotential of 283 mV to afford a current density of 10 mA cm?2, outperforming commercial RuO2 catalyst. 相似文献
15.
《International Journal of Hydrogen Energy》2022,47(51):21753-21759
Surface reconstruction produces metal oxyhydroxide (1OOH) active sites, and promoting surface reconstruction is essential for the design of OER electrocatalysts. In this paper, we reported that a large amount of active NiFeOOH was generated in-situ on the surface of nickel-iron sulfide selenide, thus exposing more active sites and efficiently catalyzing OER. In 1 M KOH solution, NiFeOOH(S,Se) achieves an ultra-low overpotential of 195 mV at the current density of 10 mA cm?2, and the Tafel slope is only 31.99 mV dec?1, showing excellent catalytic performance. When the current density is 100 mA cm?2, the over-potential of NiFeOOH(S,Se) in KOH + seawater solution is 239 mV, which is almost equivalent to 231 mV in KOH solution. The excellent OER stability of the NiFeOOH(S,Se) catalyst in alkaline electrolytes was confirmed, and the overpotential did not change significantly after 4 days of testing in KOH + seawater solution. 相似文献
16.
《International Journal of Hydrogen Energy》2022,47(54):22738-22751
Transition metal-based electrocatalysts supported on carbon substrates face the challenges of anodic corrosion of carbon during oxygen evolution reaction at high oxidation potential. The role of electrophilic functional groups (carbonyl, pyridinic, thiol, etc.) incorporated in graphene oxide has been studied towards the anodic corrosion resistance. Heteroatom functionalized carbon supports possess modified electronic properties, surface oxygen content, and hydrophilicity, which are crucial in governing electrochemical corrosion in the alkaline oxidative environment. Evidently, electron-withdrawing groups in NGO support (pyridinic, cyano, nitro, etc) and its lower oxygen content impart maximum corrosion resistance and anodic stability in comparison to the other sulfur-doped and co-doped graphene oxide support. In this report, we establish the baseline evaluation of carbon-supported OER electrocatalysts by a systematic analysis of activity and substrate corrosion resistance. The result of this study establishes the role of surface composition of the doped supports while for designing a stable, corrosion-resistant OER electrocatalyst. 相似文献
17.
18.
《International Journal of Hydrogen Energy》2022,47(59):24796-24806
Developing inexpensive and efficient electrocatalysts for hydrogen evolution reaction (HER) in both acidic and alkaline mediums is of great significance to the hydrogen energy industry. Hereby, we prepared a mixture of precursors with homogeneous composition by using the chelating ability of soybean protein isolate (C and N source) and phytic acid (dopant and phosphating agent) with cobalt ions, and achieved one-step synthesis and construction of Co2P/N–P co-doped porous carbon composite by carbonization at 800 °C. The as-synthesized Co2P/NPPC-800 electrocatalyst exhibits low HER overpotentials of 121 and 125 mV at 10 mA cm?2 in 0.5 M H2SO4 and 1.0 M KOH, which are close to those of the commercial Pt/C catalyst. Additionally, the NPPC substrate surrounding the Co2P could diminish the corrosion during the HER, and Co2P/NPPC-800 displays good stability and durability. Furthermore, this work offers a convenient synthesis strategy for phosphide/doped porous carbon composites in other electrochemical energy technologies. 相似文献
19.
《International Journal of Hydrogen Energy》2022,47(69):29781-29793
Electrocatalytic reduction of N2 to NH3 under ambient conditions, inspired by biological nitrogen fixation, is a new approach to address the current energy shortage crisis. As a result, developing efficient and low-cost catalysts is critical. The catalytic activity, catalytic mechanism, and selectivity of α-arsenene (α-Ars) catalysts anchored with various transition metal atoms and doped with different numbers of N atom were investigated for N2 reduction reaction (NRR) in this paper. Results reveal that compared with WN3-α-Ars which is coordinated with three N atoms, asym-WN2As-α-Ars that coordinated with two N atoms not only exhibits high catalytic activity (UL = ?0.36 V), but can also successfully suppress the hydrogen evolution reaction (HER). It is manifested that reducing the number of coordination atoms can promote the selectivity of the transition metal (TM) loaded N-doped arsenene catalysts. Furthermore, activity origin analyses show both the charge on 1N–NH and φ form volcano-type relationship with the limiting potential. The active center of the catalyst, which acts as the charge transporter and has the moderate ability to retrieve charges, is the most efficient in NRR. Overall, this research creates high performance NRR catalysts by varying the number of coordinating N atoms, which provides a novel idea for the development of new NRR catalysts. 相似文献
20.
《International Journal of Hydrogen Energy》2022,47(71):30494-30502
Metal-organic frameworks (MOFs) have emerged as efficient electrocatalysts due to the features of high specific surface area, rich pore structure and diversified composition. It is still challenging to synthesize self-supporting MOF-based catalysts using simple and low-cost fabrication methods. Herein, we successfully fabricated Ni-doped MIL-53(Fe) supported on nickel-iron foam (Ni-MIL-53(Fe)/NFF) as efficient electrocatalyst. A facile two-step solvothermal method without adding any metal salts was used, which can simplify the fabrication process and reduce the experimental cost. In the fabrication process, the bimetallic Ni-MIL-53(Fe)/NFF was in situ converted from an intermediate NiFe2O4/NFF. The obtained material exhibits outstanding electrocatalytic oxygen evolution performance with a low overpotential of 248 mV at 50 mA cm?2, and a small Tafel slope of 46.4 mV dec?1. This work sheds light on the simple and efficient preparation of bimetallic MOF-based material, which is promising in electrocatalysts. 相似文献