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排序方式: 共有8094条查询结果,搜索用时 15 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(83):35423-35436
The gas diffusion substrate (GDS) is essential in the proton exchange membrane fuel cells. Its fabrication techniques affect the performance significantly and are worthy of investigation. In this study, a manufacturing process of the GDS is proposed to understand the formation process of GDS and promote its structure and performance more pertinently. Different states during the preparation process, raw carbon paper, pre-curing, curing, carbonation, and graphitization, are characterized and measured. Experimental and numerical methods are employed to determine the relationships between microstructure, transport, and mechanical performance variation with the fabricating processes. The results show that its porosity, average pore size, and effective diffusivity decrease first and increase after curing. These parameters after graphitization are lower than that of the carbon paper (CP). The electrical resistivity increases dramatically while pre-curing and decreases gradually after curing, carbonation, and graphitization, and it is much reduced after graphitization. Moreover, mechanical measurement results show that both the picks of tensile strength and flexural modulus occur after curing. Its tensile strength shows little change after graphitization compared to the initial paper's. In contrast, the flexural modulus is improved significantly. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(61):25769-25779
Gas diffusion layer (GDL) is one of the most important components of fuel cells. In order to improve the fuel cell performance, GDL has developed from single layer to dual layers, and then to multiple layers. However, dual or multi layers in GDL are usually prepared by layer-by-layer methods, which cost too much time, energy, and resources. In this work, we successfully developed a facile one-step method to prepare a GDL with three functional layers by utilizing the different sedimentation rates and filtration rates of short carbon fiber (CF) and carbon nanotube (CNT). The treatment temperature for this GDL is much lower than that of traditional method. The thickness of the GDL can be effectively controlled from as thin as 50 μm to more than 200 μm by simply adjusting the content of CF. The GDL with high flexibility is suitable to develop high performance flexible electronics. The fuel cell with the GDL has the maximum power density 1021 mW cm?2, which shows 19% improvement comparing to the conventional one. Therefore, this work breaks the traditional concept that GDL for fuel cells only can be prepared by very complex and high-cost procedure. 相似文献
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4.
制浆造纸行业水污染全过程控制技术理论与实践 总被引:1,自引:0,他引:1
制浆造纸行业是我国水污染防治的重点,减排任务艰巨。在环境倒逼下,造纸行业加快淘汰落后产能和完善末端治理技术,污染控制取得了初步成效。但随着国家和地方环境治理由浓度控制走向总量控制、质量控制,原有技术的局限性难以满足解决水污染的更高要求,必须创新污染防治方法。本文介绍了制浆造纸行业水污染全过程控制的基本理论和内涵,并结合化学法制浆、化学机械法制浆、废纸制浆与造纸过程水污染防治工程实践,提出了解决制浆造纸行业水污染的对策,为推动行业绿色转型升级和高质量发展提供了支撑。 相似文献
5.
国内外纸质文献加固技术研究 总被引:1,自引:1,他引:0
纸张脆化问题既缩短了纸质文献的保存寿命,又限制了纸质文献的使用、研究与传承,对脆化纸质文献进行加固处理迫在眉睫。现有纸质文献加固技术使用的材料可以分为天然材料、合成材料以及复合材料三大类。本文从这三方面对纸质文献加固技术的研究进展进行了介绍,并综合考虑我国文献保护的实际情况,提出了开展纸质文献加固工作应遵循的原则和未来的研究方向,旨在为脆化纸质文献加固处理提供借鉴。 相似文献
6.
研究了卷烟机针辊回丝量电压值、大风机压力、小风机压力等卷烟机关键工艺参数对细支烟机台运行情况和烟支物理质量的影响规律。结果表明:①针辊回丝量、大风机压力、小风机压力对细支卷烟机台设备运行情况和细支烟物理质量指标均有不同程度的影响;②回丝量对平整盘位置和空头率影响显著(P<0.05);③随着回丝量的增大,平整盘位置减小,压实量增大,空头率减小;④大风机压力对平整盘位置影响显著(P<0.05);⑤随着大风机负压的增大,平整盘位置减小。综上,增加回丝量可以减小细支烟空头率,改善细支烟的质量。 相似文献
7.
This study examined airborne emissions from cigarette butts for styrene, 2-methyl-2-cyclopenten-1-one, naphthalene, triacetin, and nicotine. Ten experiments were conducted by placing butts in a stainless steel chamber and measuring the chemical concentrations in chamber air. Emission rates were determined from the concentrations. Triacetin and nicotine concentrations were roughly 50% of initial concentrations after 100 hours, while concentrations of other chemicals decayed to less than 10% of initial concentrations within 24 hours. Initial emission rates per cigarette butt ranged from 200 to 3500 ng h−1. Triacetin and nicotine emission rates at 25°C were 1.6 to 2.2 times higher than the rates at 20°C, while the emission rates of other chemicals at 25°C were 1.1 to 1.3 times higher than the rates at 20°C only during the first sampling period. The chemical concentrations and emission rates at 30°C were comparable or lower than the values at 25°C, possibly due to different batches of cigarettes used. The 24-hours emitted mass of nicotine from a cigarette butt at 25°C could be up to 14% of the literature reported nicotine masses emitted from a burning cigarette. 相似文献
8.
Harshita Gogoi V. Nirosha Anjali Jayakumar Keerthana Prabhu Meghna Maitra 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2018,40(1):39-44
In the present study, pre-treated paper mill sludge (PMS) was evaluated extensively as a substrate for production of acetone-butanol-ethanol using Clostridium sporogenes NCIM 2337. The PMS was subjected to three types of pre-treatment methods namely alkali, mechanical, and thermal treatment and was analyzed by SEM. The pre-treatment of PMS by alkali was observed to be more effective over the other pre-treatment methods. The alkali pre-treated sludge was then made to undergo fermentation, which showed the conventional process of acidogenesis followed by solventogenesis. The acetone, butanol, and ethanol concentration for 15% alkali pre-treated PMS was estimated to be maximum. 相似文献
9.
衣康酸改性苯丙胶乳及其在阻燃性空气滤纸中的应用 总被引:1,自引:1,他引:0
本研究采用衣康酸作为功能性单体对苯丙胶乳进行改性,并将改性苯丙胶乳与阻燃剂复配,以浸渍施胶的方式对阻燃性空气滤纸的性能进行改善。研究表明,经衣康酸改性后的苯丙胶乳颗粒平均粒径为0. 0868μm,比改性前降低34. 7%,机械稳定性、稀释稳定性及固含量均表现良好;当衣康酸用量为2%(占单体总质量)时,浸渍改性苯丙胶乳使纸张透气度降低约2. 27%,挺度及耐破度达最优值,分别为3. 40 mN?m和290 kPa,比浸渍改性前的苯丙胶乳分别提高了27. 8%及18. 4%。将阻燃剂与改性苯丙胶乳按质量比1:1.4进行复配后对空气滤纸原纸浸渍后发现,纸张的挺度、耐破度及极限氧指数达4. 07 mN?m、301 kPa和30. 9%,满足我国有关阻燃性空气滤纸行业标准的性能要求。 相似文献
10.
两亲改性碳纤维制备质子交换膜燃料电池用碳纸的研究 总被引:1,自引:1,他引:0
为了提高短切碳纤维在水中的分散性及碳纤维与后期浸渍树脂的相容性,对碳纤维进行了两亲表面处理:首先通过氧化处理使其获得亲水性官能团—OH及—COOH,在此基础上进一步接枝亲油基团,以获得两亲碳纤维,并将其制备碳纸。结果表明,两亲处理的碳纤维表面—OH含量可达8. 2%。在碳纤维表面改性过程中,铬酸氧化在提高碳纤维表面亲水性官能团的同时会降低碳纸的抗张强度;而接枝亲油性官能团能提高碳纤维与树脂的黏结能力,部分弥补了表面处理所造成的负面影响;碳纤维与树脂黏结力的提高有利于碳纸导电性的提高,两亲改性碳纤维制备的碳纸与未处理碳纤维制备碳纸相比电阻率降低了31. 4%,达到10. 5 mΩ·cm。 相似文献