全文获取类型
收费全文 | 19731篇 |
免费 | 2039篇 |
国内免费 | 742篇 |
专业分类
电工技术 | 4387篇 |
技术理论 | 1篇 |
综合类 | 1847篇 |
化学工业 | 2354篇 |
金属工艺 | 350篇 |
机械仪表 | 623篇 |
建筑科学 | 4556篇 |
矿业工程 | 851篇 |
能源动力 | 1275篇 |
轻工业 | 1749篇 |
水利工程 | 665篇 |
石油天然气 | 436篇 |
武器工业 | 36篇 |
无线电 | 685篇 |
一般工业技术 | 992篇 |
冶金工业 | 701篇 |
原子能技术 | 32篇 |
自动化技术 | 972篇 |
出版年
2024年 | 60篇 |
2023年 | 348篇 |
2022年 | 554篇 |
2021年 | 750篇 |
2020年 | 825篇 |
2019年 | 617篇 |
2018年 | 519篇 |
2017年 | 576篇 |
2016年 | 663篇 |
2015年 | 661篇 |
2014年 | 1507篇 |
2013年 | 1082篇 |
2012年 | 1459篇 |
2011年 | 1425篇 |
2010年 | 1193篇 |
2009年 | 1247篇 |
2008年 | 1152篇 |
2007年 | 1501篇 |
2006年 | 1300篇 |
2005年 | 1076篇 |
2004年 | 847篇 |
2003年 | 790篇 |
2002年 | 622篇 |
2001年 | 488篇 |
2000年 | 397篇 |
1999年 | 238篇 |
1998年 | 126篇 |
1997年 | 101篇 |
1996年 | 75篇 |
1995年 | 69篇 |
1994年 | 57篇 |
1993年 | 32篇 |
1992年 | 38篇 |
1991年 | 26篇 |
1990年 | 32篇 |
1989年 | 19篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1958年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Xiao-Jing Hou Liu-Ying Yu Chao-Hong He Ke-Jun Wu 《American Institute of Chemical Engineers》2022,68(2):e17408
Deep eutectic solvents (DESs) are mixtures of two or more components that have lower melting temperatures compared to their constituting components. DESs possess many advantages, for example, low volatility, low flammability, and low toxicity, which make them promising alternatives to traditional organic solvents. The melting temperature, one of the important physical properties, is of essential importance for industrial applications. In this work, a group and group-interaction contribution method was proposed to estimate the melting temperatures of DESs using an extensive database (1528 DESs, 1541 data points). The average absolute relative deviation (%AARD) between the estimated and experimental values of the melting temperature was 5.67% for binary DESs. Subsequently, this method was also extended to estimate the melting temperature of ternary DESs, with the AARD of 6.13%. The results indicate the high accuracy and broad applicability of the method and pave the way for the rational design of task-specific DESs. 相似文献
72.
《Ceramics International》2022,48(7):9746-9752
In this work, the photocatalytic degradation of malachite green (MG) solutions by β-Ga2O3 was investigated. The latter was synthetized by reacting gallium nitrate with concentrated formic acid, which produced gallium formate. The thermal decomposition of this compound at 850 °C produced single-phase β-Ga2O3. The resulting morphology corresponds to non-agglomerated microcubes, with a size in the range of 0.8 and 2.3 μm. The surface chemical composition and bandgap energy of this oxide were determined by X-ray photoelectron spectroscopy (XPS) and the Tauc method, respectively. The photodegradation of MG was carried out under violet light (λ = 405 nm), at room temperature, using the as-prepared powder. The results revealed a fast degradation of the dye during the first 20 min, which attenuates over time. The rate of photodegradation depends on the amount of β-Ga2O3 used and can be fitted by an exponential equation. The role of free hydroxyl radicals and reactive oxygen species in photocatalysis was addressed by using analytic techniques (FTIR and XPS). 相似文献
73.
目的 从绿色家具视角和纸绳家具设计实例出发,探究纸绳家具的设计原则和方法,旨在为实际应用提供一种新的思路.方法 通过对纸绳材料优势的深入分析,结合实例和现阶段绿色家具的设计要求,分析"6R""以人为本"设计原则在纸绳家具设计中的应用,并指导设计实践.结论 "6R"和"以人为本"的设计原则对纸绳家具设计具有指导作用,所设计的纸绳家具不仅能够避免复合纸板家具不耐水、不耐久等不足,也赋予纸家具产品温馨的人文主义气息,达到功能性与艺术性的完美统一.与此同时,在充分了解材料属性的基础上,赋予纸绳家具可回收、再循环和再利用的环保属性,拟满足当代消费者对产品实用性和环保性的双重要求,这对纸材料在家具设计中的进一步拓展具有重要意义. 相似文献
74.
The Malaysian electricity industry evolved from a vertically integrated utility into a single-buyer model, which considered a precursor to deregulation and a competitive market. This study considers electricity sector reform in Malaysia and proposes a market structure for the industry. We focus on the single-buyer model and the pool model for the analysis with the recommendation on reform stages required to ensure a smooth and successful market transition. A smooth transition from regulated market into deregulated market will ensure market stability and sustainability of the energy market. It will also provide enough time for the market participants to adapt and transit from regulated to deregulated energy market. 相似文献
75.
Jingming Ning Gary G. Hou Jingjing Sun Zhengzhu Zhang Xaiochun Wan 《International Journal of Food Science & Technology》2019,54(2):576-582
The effects of green tea powder (GTP) on the properties of hard red winter (HRW) flour and Chinese steamed bread were investigated. GTP was blended with HRW flour at levels of 0.00, 1.00, 2.00, 3.00 and 4.00 g GTP/100 g wheat flour. With the addition of GTP, the maximum torque of flour became stronger. The resilience and degree of green colour of steamed bread increased, while hardness and chewiness decreased, with the addition of GTP. The addition of 1.00% GTP did not significantly affect the specific volume, but remarkably influenced the hardness and resilience of steamed bread. In steamed bread formulated with GTP, the antioxidant activity was 0.84 mm TE per g at 1.00% of GTP and increased with GTP levels. The steamed bread had a pleasant flavour, and the degree of overall liking of steamed bread increased with GTP levels to the maximum used in this work. 相似文献
76.
超声波解冻与传统解冻方式的比较与竞争力评估 总被引:3,自引:0,他引:3
超声波解冻通过空化效应、机械效应和热效应对冷冻食品进行解冻,解冻效率高、对冷冻食品的损伤较小。该文简要介绍了空气解冻、水解冻和电解冻的解冻机制及研究进展,详细阐述了超声波解冻的机制及研究进展。将超声波解冻与空气解冻、水解冻和电解冻进行对比,发现超声波解冻的解冻效率最优,且将超声波与这3种传统解冻方式结合可以提高解冻效率,并且获得更好的解冻效果。超声波频率和强度以及冻结食品的解冻温度是影响解冻效果的主要参数。超声波在食品中的衰减程度受到解冻温度的影响极大,因此在调节超声波频率和强度同时调控解冻温度对解冻效果至关重要。 相似文献
77.
Gianmarco Mangiaterra Elisa Carotti Salvatore Vaiasicca Nicholas Cedraro Barbara Citterio Anna La Teana Francesca Biavasco 《International journal of molecular sciences》2021,22(4)
The occurrence of Pseudomonas aeruginosa (PA) persisters, including viable but non-culturable (VBNC) forms, subpopulations of tolerant cells that can survive high antibiotic doses, is the main reason for PA lung infections failed eradication and recurrence in Cystic Fibrosis (CF) patients, subjected to life-long, cyclic antibiotic treatments. In this paper, we investigated the role of subinhibitory concentrations of different anti-pseudomonas antibiotics in the maintenance of persistent (including VBNC) PA cells in in vitro biofilms. Persisters were firstly selected by exposure to high doses of antibiotics and their abundance over time evaluated, using a combination of cultural, qPCR and flow cytometry assays. Two engineered GFP-producing PA strains were used. The obtained results demonstrated a major involvement of tobramycin and bacterial cell wall-targeting antibiotics in the resilience to starvation of VBNC forms, while the presence of ciprofloxacin and ceftazidime/avibactam lead to their complete loss. Moreover, a positive correlation between tobramycin exposure, biofilm production and c-di-GMP levels was observed. The presented data could allow a deeper understanding of bacterial population dynamics during the treatment of recurrent PA infections and provide a reliable evaluation of the real efficacy of the antibiotic treatments against the bacterial population within the CF lung. 相似文献
78.
低共熔溶剂(DESs)具有原料廉价易得、化学稳定性好、可设计、合成工艺简单、可循环使用和绿色环保等优点,在CO2捕集领域受到广泛关注。重点综述了近年来DESs用于CO2捕集的研究进展,总结了DESs捕集CO2的能力,分析了DESs捕集CO2的影响因素和DESs的循环使用性能,归纳了DESs捕集CO2的机理(包括物理吸收、化学吸收和物理化学协同吸收),并总结了CO2在DESs中的溶解度计算模型。分析发现,DESs捕集CO2的影响因素中,温度、压力和水含量(质量分数)均对CO2的捕集有影响,且DESs的结构是重要的影响因素;大部分DESs可循环使用;CO2在DESs中溶解度计算模型的建立有效推动了DESs捕集CO2的进一步发展。最后,指出了DESs捕集分离CO2所面临的主要问题并对进一步的研究工作进行了分析讨论。 相似文献
79.
In this study, two types of convolutional neural network (CNN) classifiers are designed to handle the problem of classifying black plastic wastes. In particular, the black plastic wastes have the property of absorbing laser light coming from spectrometer. Therefore, the classification of black plastic wastes remains still a challenging problem compared to classifying other colored plastic wastes using existing spectroscopy (i.e., NIR). When it comes the classification problem of black plastic wastes, effective classification techniques by the laser spectroscopy of Fourier Transform-Infrared Radiation (FT-IR) with Attenuated Total Reflectance (ATR) and Raman to analyze the classification problem of black plastic wastes are introduced. Due to the strong ability of extracting spatial features and remarkable performance in image classification, 1D and 2D CNN through data features are designed as classifiers. The technique of chemical peak points selection is considered to reduce data redundancy. Furthermore, through the selection of data features based on the extracted 1D data with peak points is introduced. Experimental results demonstrate that 2DCNN classifier designed with the help of 2D data feature selection as well as 1DCNN classifier shows the best performance compared with other reported methods for classifying black plastic wastes. 相似文献
80.
Optimizing the lignin based synthesis of flexible polyurethane foams employing reactive liquefying agents 下载免费PDF全文
Jacopo Bernardini Irene Anguillesi Maria‐Beatrice Coltelli Patrizia Cinelli Andrea Lazzeri 《Polymer International》2015,64(9):1235-1244
The present work is focused on the optimization of a green process based on the employment of by‐products obtained from wood treatments as raw materials for producing flexible polyurethane foams. More specifically, lignin was employed in flexible polyurethane foams in order to partially replace the usual fossil polyols; therefore glycerol (GLY) and glycerin polyglycidyl ether (EJ 300) were used as the polyol fraction for lignin liquefaction. Polypropylene glycol triol was used as a chain extender in different ratios with liquefaction solvents, and polymeric diphenylmethane diisocyanate as an isocyanate fraction. Liquefaction of lignin was performed by microwave irradiation, thus reducing the processing time and energy required compared to present industrial production processes. All the foams were produced in controlled expansion through the adoption of a ‘one‐shot’ approach, using water as a blowing agent and with an isocyanate index (NCO/OH) of less than 100 to improve the flexibility of the foam. This approach allowed for the substitution of up to 12% of common petro derived polyol with commercial soda lignin. Finally, the foams were characterized, presenting properties that could be modulated as a function of lignin content, GLY/EJ 300 ratio and isocyanate index. The qualities of the foams were compatible with existing materials used for furniture and for the interiors of car seats and couches. © 2015 Society of Chemical Industry 相似文献