全文获取类型
收费全文 | 18019篇 |
免费 | 1420篇 |
国内免费 | 158篇 |
专业分类
电工技术 | 259篇 |
综合类 | 78篇 |
化学工业 | 4611篇 |
金属工艺 | 409篇 |
机械仪表 | 717篇 |
建筑科学 | 601篇 |
矿业工程 | 29篇 |
能源动力 | 1230篇 |
轻工业 | 1864篇 |
水利工程 | 240篇 |
石油天然气 | 251篇 |
武器工业 | 5篇 |
无线电 | 1971篇 |
一般工业技术 | 3537篇 |
冶金工业 | 565篇 |
原子能技术 | 138篇 |
自动化技术 | 3092篇 |
出版年
2024年 | 97篇 |
2023年 | 440篇 |
2022年 | 978篇 |
2021年 | 1489篇 |
2020年 | 1123篇 |
2019年 | 1230篇 |
2018年 | 1301篇 |
2017年 | 1160篇 |
2016年 | 1148篇 |
2015年 | 683篇 |
2014年 | 995篇 |
2013年 | 1704篇 |
2012年 | 1103篇 |
2011年 | 1198篇 |
2010年 | 800篇 |
2009年 | 715篇 |
2008年 | 499篇 |
2007年 | 435篇 |
2006年 | 334篇 |
2005年 | 216篇 |
2004年 | 206篇 |
2003年 | 176篇 |
2002年 | 135篇 |
2001年 | 98篇 |
2000年 | 99篇 |
1999年 | 93篇 |
1998年 | 151篇 |
1997年 | 121篇 |
1996年 | 104篇 |
1995年 | 84篇 |
1994年 | 58篇 |
1993年 | 68篇 |
1992年 | 54篇 |
1991年 | 45篇 |
1990年 | 41篇 |
1989年 | 37篇 |
1988年 | 29篇 |
1987年 | 29篇 |
1986年 | 35篇 |
1985年 | 33篇 |
1984年 | 30篇 |
1983年 | 27篇 |
1982年 | 25篇 |
1981年 | 22篇 |
1980年 | 20篇 |
1979年 | 19篇 |
1978年 | 20篇 |
1977年 | 21篇 |
1976年 | 24篇 |
1975年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Eivazzadeh-Keihan Reza Noruzi Ehsan Bahojb Mehrban Sarah Fattahi Aliabadi Hooman Aghamirza Moghim Karimi Meghdad Mohammadi Adibeh Maleki Ali Mahdavi Mohammad Larijani Bagher Shalan Ahmed Esmail 《Journal of Materials Science》2022,57(6):3855-3891
Journal of Materials Science - Chitosan is one of the natural cationic polymers with unique properties such as non-toxicity, biodegradability, biocompatibility, environmentally friendly that has... 相似文献
3.
Muhammad Yazid Samatra Nor Qhairul Izzreen Mohd Noor Umi Hartina Mohamad Razali Jamilah Bakar Sharifudin Md. Shaarani 《Comprehensive Reviews in Food Science and Food Safety》2022,21(4):3153-3176
Gelatin is one of the most important multifunctional biopolymers and is widely used as an essential ingredient in food, pharmaceutical, and cosmetics. Porcine gelatin is regarded as the leading source of gelatin globally then followed by bovine gelatin. Porcine sources are favored over other sources since they are less expensive. However, porcine gelatin is religiously prohibited to be consumed by Muslims and the Jewish community. It is predicted that the global demand for gelatin will increase significantly in the future. Therefore, a sustainable source of gelatin with efficient production and free of disease transmission must be developed. The highest quality of Bovidae-based gelatin (BG) was acquired through alkaline pretreatment, which displayed excellent physicochemical and rheological properties. The utilization of mammalian- and plant-based enzyme significantly increased the gelatin yield. The emulsifying and foaming properties of BG also showed good stability when incorporated into food and pharmaceutical products. Manipulation of extraction conditions has enabled the development of custom-made gelatin with desired properties. This review highlighted the various modifications of extraction and processing methods to improve the physicochemical and functional properties of Bovidae-based gelatin. An in-depth analysis of the crucial stage of collagen breakdown is also discussed, which involved acid, alkaline, and enzyme pretreatment, respectively. In addition, the unique characteristics and primary qualities of BG including protein content, amphoteric property, gel strength, emulsifying and viscosity properties, and foaming ability were presented. Finally, the applications and prospects of BG as the preferred gelatin source globally were outlined. 相似文献
4.
5.
F.T. Munna Vidhya Selvanathan K. Sobayel Ghulam Muhammad Nilofar Asim Nowshad Amin Kamaruzzaman Sopian Md. Akhtaruzzaman 《Ceramics International》2021,47(8):11003-11009
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell. 相似文献
6.
Hoseinzade Kimia Mousavi-Mashhadi Seyed Ali Shiri Ali 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(12):4648-4658
Journal of Inorganic and Organometallic Polymers and Materials - Immobility of copper on magnetic nanoparticles was performed using surface rectification of Fe3O4 with Agar. The magnetic... 相似文献
7.
Tourajizadeh Hami Yousefzadeh Mahdi Khalaji Ali Keymasi Bamdad Mahdi 《International Journal of Control, Automation and Systems》2022,20(5):1671-1681
International Journal of Control, Automation and Systems - In this paper, a new controllable simulator is proposed and modeled by which, experimental tests of the aircraft’s models can be... 相似文献
8.
Catalysis Letters - In the present paper, an efficient Cu-catalyzed regioselective acylation of indoles with phenylglyoxals was developed which is the first example of indolyl diketones synthesis... 相似文献
9.
Jiao Zhang Junjie Li Ayesha Murtaza Aamir Iqbal Lijuan Zhu Shinawar Waseem Ali Muhammad Usman Roshan Yameen Siyi Pan Wanfeng Hu 《International Journal of Food Science & Technology》2022,57(2):963-973
This work evaluated the synergistic effects of combined high-intensity ultrasound (HIU) with β-cyclodextrin (β-CD) treatments on inhibiting browning of apple juice and explored the mechanism through simulation system. The combined treatment of 300 W HIU with 0.006 g mL−1 β-CD had a synergistic impact on maintaining juice colour, resulting in a 39.06% reduction in browning degree, only a 36.64% decrease in total phenolic content, and a 17.82% reduction in PPO activity. The inhibition of enzymatic browning in simulated system revealed that HIU suppressed the enzyme (Polyphenol oxidase, PPO) and β-CD inhibited enzyme (PPO) and embedded substrate (polyphenol). The results of spectroscopic analysis showed that the particle-size distribution of PPO narrowed, the content of α-helix in the secondary structure increased, the fluorescence intensity increased, and the maximum wavelength was red-shifted after HIU and β-CD treatment. Changes in structure could further result in PPO activity loss. Hence, the combined treatment could synthetically alleviate the browning of apple juice. 相似文献
10.
Seredin P. V. Radam Ali Obaid Goloshchapov D. L. Len’shin A. S. Buylov N. S. Barkov K. A. Nesterov D. N. Mizerov A. M. Timoshnev S. N. Nikitina E. V. Arsentyev I. N. Sharafidinov Sh. Kukushkin S. A. Kasatkin I. A. 《Semiconductors》2022,56(4):253-258
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid... 相似文献