全文获取类型
收费全文 | 2148篇 |
免费 | 157篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 36篇 |
综合类 | 6篇 |
化学工业 | 552篇 |
金属工艺 | 46篇 |
机械仪表 | 91篇 |
建筑科学 | 81篇 |
矿业工程 | 4篇 |
能源动力 | 135篇 |
轻工业 | 268篇 |
水利工程 | 30篇 |
石油天然气 | 43篇 |
无线电 | 206篇 |
一般工业技术 | 389篇 |
冶金工业 | 109篇 |
原子能技术 | 11篇 |
自动化技术 | 315篇 |
出版年
2024年 | 6篇 |
2023年 | 39篇 |
2022年 | 53篇 |
2021年 | 130篇 |
2020年 | 115篇 |
2019年 | 117篇 |
2018年 | 158篇 |
2017年 | 122篇 |
2016年 | 141篇 |
2015年 | 91篇 |
2014年 | 123篇 |
2013年 | 267篇 |
2012年 | 125篇 |
2011年 | 160篇 |
2010年 | 105篇 |
2009年 | 89篇 |
2008年 | 65篇 |
2007年 | 44篇 |
2006年 | 23篇 |
2005年 | 43篇 |
2004年 | 26篇 |
2003年 | 25篇 |
2002年 | 15篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 15篇 |
1998年 | 26篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1981年 | 4篇 |
1979年 | 6篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1970年 | 5篇 |
1966年 | 6篇 |
1961年 | 3篇 |
排序方式: 共有2322条查询结果,搜索用时 75 毫秒
1.
2.
3.
4.
5.
Huseyin Avci Esra Akkulak Hazal Gergeroglu Hamed Ghorbanpoor Onur Uysal Ayla Eker Sariboyaci Bahar Demir Merve Nur Soykan Suat Pat Reza Mohammadigharehbagh Ceren Özel Ahmet Cabuk Fatma Doğan Güzel 《应用聚合物科学杂志》2020,137(26):49184
Among the thermoplastic elastomers that play important roles in the polymer industry due to their superior properties, styrene-based species and polyurethane block copolymers are of great interest. Poly(styrene-ethylene-butadiene-styrene) (SEBS) as a triblock copolymer seems to have the potential to meet many demands in different applications due to various industrial requirements where durability, biocompatibility, breaking elongation, and interfacial adhesion are important. In this study, the SEBS triblock copolymer was functionalized with natural (Satureja hortensis, SH) and synthetic (nanopowder, TiO2) agents to obtain composite nanofibers by electrospinning and electrospraying methods for use in biomedical and water filtration applications. The results were compared with thermoplastic polyurethane (TPU) composite nanofibers, which are commonly used in these fields. Here, functionalized SEBS nanofibers exhibited antibacterial effect while at the same time improving cell viability. In addition, because of successful water filtration by using the SEBS composite nanofibers, the material may have a good potential to be used comparably to TPU for the application. 相似文献
6.
Alinda Samsuri Mohd Nor Latif Mohd Razali Shamsuddin Fairous Salleh Maratun Najiha Abu Tahari Tengku Shafazila Tengku Saharuddin Norliza Dzakaria Mohd Ambar Yarmo 《International Journal of Hydrogen Energy》2021,46(48):24831-24844
Temperature programmed reduction (TPR) analysis was applied to investigate the chemical reduction progression behavior of molybdenum oxide (MoO3) catalyst. The composition and morphology of the reduced phases were characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FE-SEM). The reduction progression of MoO3 catalyst was attained with different reductant types and concentration (10% H2/N2, 10% and 20% CO/N2 (%, v/v)). Two different modes of reduction process were applied. The first approach of reduction involved non-isothermal mode reduction up to 700 °C, while the second approach of reduction involved the isothermal mode reduction for 60 min at 700 °C. Hydrogen temperature programmed reduction (H2-TPR) results showed the reduction progression of three-stage reduction of MoO3 (Mo6+ → Mo5+ → Mo4+ → Mo0) with Mo5+ and Mo4+. XRD analysis confirmed the formation of Mo4O11 phase as an intermediate phase followed by MoO2 phase. After 60 min of isothermal reduction, peaks of metallic molybdenum (Mo) appeared. Whereas, FESEM analysis showed porous crater-like structure on the surface cracks of MoO2 layer which led to the growth of Mo phase. Meanwhile, the reduction of MoO3 catalyst in 10% carbon monoxide (CO) showed the formation of unstable intermediate phase of Mo9O26 at the early stage of reduction. Furthermore, by increasing 20% CO led to the carburization of MoO2 phase, resulted in the formation of Mo2C rather than the formation of metallic Mo, as confirmed by XPS analysis. Therefore, the presented study shows that hydrogen gave better reducibility due to smaller molecular size, which contributed to high diffusion rate and achieved deeper penetration into the MoO3 catalyst compared to carbon monoxide reductant. Hence, the reduction of MoO3 in carbon monoxide atmosphere promoted the formation of Mo2C which was in agreement with the thermodynamic assessment. 相似文献
7.
Parisa Solhi Sodeif Azadmard‐Damirchi Javad Hesari Hamed Hamishehkar 《International Journal of Dairy Technology》2020,73(1):226-233
The qualitative properties of processed cheese (PC) fortified with different levels of asparagus powder (AP) (0.5%, 1% and 1.5% wt/wt) were evaluated during storage. AP decreased the pH and lipolysis indexes and increased the phenolic content, antioxidant activity and proteolysis of the processed cheeses. AP made the structure of the cheese more elastic, increased the rigidity and decreased the spreadability compared with the control sample, which corresponded to the results obtained using dynamic oscillatory rheometry. The results showed that AP as a rich source of bioactive components could be used for the fortification of processed cheeses. 相似文献
8.
Discrete time queueing systems have been successfully used to model packet queues in computer and digital communications systems. In this article we introduce a novel approach to analyzing the GeoX/GeoY/∞ queueing system, which is suitable for modelling high speed computer and communications systems. The approach is based on characterizing the system by a functional equation which is then solved recursively to give identical results to those obtained using other approaches. 相似文献
9.
10.
Elias G. Abu‐Saba William M. McGinley Raymond C. Montgomery 《Canadian Metallurgical Quarterly》1991,4(4):347-354
As the manned exploration of space continues, many complex structural components are being developed to construct the orbital platforms that will be used to house communication hardware, personnel, and manufacturing complexes. These components are extremely flexible and complex in their behavior. There is a need for a simple method for determining the dynamic characteristics of these space structures with a minimum of effort. A mathematical model of one of these structural elements, an articulating truss beam, has been developed to predict its dynamic response. Assumptions of the force interaction between the beam elements and the joints have been made for using this model. Algorithms are provided to determine the flexibility matrix of the truss beam for use in the equation of motion. The natural frequencies obtained from using this method are compared with those obtained by the finite element method. An experimental procedure is planned to validate the results from the theoretical method. 相似文献