全文获取类型
收费全文 | 130316篇 |
免费 | 12311篇 |
国内免费 | 6821篇 |
专业分类
电工技术 | 8797篇 |
技术理论 | 13篇 |
综合类 | 11137篇 |
化学工业 | 20223篇 |
金属工艺 | 7683篇 |
机械仪表 | 8510篇 |
建筑科学 | 10172篇 |
矿业工程 | 3599篇 |
能源动力 | 3653篇 |
轻工业 | 12385篇 |
水利工程 | 2606篇 |
石油天然气 | 7027篇 |
武器工业 | 1239篇 |
无线电 | 14003篇 |
一般工业技术 | 13898篇 |
冶金工业 | 4994篇 |
原子能技术 | 1419篇 |
自动化技术 | 18090篇 |
出版年
2024年 | 477篇 |
2023年 | 2168篇 |
2022年 | 4059篇 |
2021年 | 5673篇 |
2020年 | 4365篇 |
2019年 | 3380篇 |
2018年 | 3716篇 |
2017年 | 4260篇 |
2016年 | 3696篇 |
2015年 | 5518篇 |
2014年 | 6981篇 |
2013年 | 8058篇 |
2012年 | 9339篇 |
2011年 | 10236篇 |
2010年 | 9096篇 |
2009年 | 8555篇 |
2008年 | 8591篇 |
2007年 | 8025篇 |
2006年 | 7739篇 |
2005年 | 6256篇 |
2004年 | 4350篇 |
2003年 | 3783篇 |
2002年 | 3888篇 |
2001年 | 3301篇 |
2000年 | 2764篇 |
1999年 | 2527篇 |
1998年 | 1824篇 |
1997年 | 1429篇 |
1996年 | 1268篇 |
1995年 | 993篇 |
1994年 | 801篇 |
1993年 | 554篇 |
1992年 | 463篇 |
1991年 | 330篇 |
1990年 | 243篇 |
1989年 | 202篇 |
1988年 | 126篇 |
1987年 | 107篇 |
1986年 | 76篇 |
1985年 | 43篇 |
1984年 | 23篇 |
1983年 | 28篇 |
1982年 | 26篇 |
1981年 | 28篇 |
1980年 | 40篇 |
1979年 | 12篇 |
1978年 | 4篇 |
1960年 | 2篇 |
1959年 | 9篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
41.
42.
Xiaohui Hu Li Cheng Yan Hong Zhaofeng Li Caiming Li Zhengbiao Gu 《International Journal of Food Science & Technology》2021,56(8):4149-4158
Incorporating high level of potato flour into wheat flour enhances nutritional values of bread but induces a series of problems that lead to the decline of the bread quality. To overcome the barrier, wheat gluten and carboxymethylcellulose (CMC) were added into potato–wheat composite flour to improve dough machinability and bread quality. The rheological properties, thermo-mechanical properties and microstructures of dough were investigated. The results showed that the interaction between gluten and CMC mitigated the discontinuity of gluten matrix and gluten protein aggregation caused by the addition of potato flour, which yielded a more branched and compact gluten network. The compact three-dimensional viscoelastic structure induced improvements of gas retention capacity and dough stability, making it mimic the machinability properties of wheat flour dough. Bread qualities were apparently improved with the combined use of 4% gluten and 6% CMC, of which specific volume increased by 42.86%, and simultaneously, hardness reduced by 75.93%. 相似文献
43.
44.
45.
46.
Controllability and observability of multi-agent systems with heterogeneous and switching topologies
ABSTRACTThis paper focuses on controllability and observability of multi-agent systems with heterogeneous and switching topologies, where the first- and the second-order information interaction topologies are different and switching. First, based on the controllable state set, a controllability criterion is obtained in terms of the controllability matrix corresponding to the switching sequence. Next, by virtue of the subspace sequence, two necessary and sufficient algebraic conditions are established for controllability in terms of the system matrices corresponding to all the possible topologies. Furthermore, controllability is considered from the graphic perspective. It is proved that the system is controllable if the union graph of all the possible topologies is controllable. With respect to observability, two sufficient and necessary conditions are derived by taking advantage of the system matrices and the corresponding invariant subspace, respectively. Finally, some simulation examples are worked out to illustrate the theoretical results. 相似文献
47.
48.
Ionomics is a novel multidisciplinary field that uses advanced techniques to investigate the composition and distribution of all minerals and trace elements in a living organism and their variations under diverse physiological and pathological conditions. It involves both high-throughput elemental profiling technologies and bioinformatic methods, providing opportunities to study the molecular mechanism underlying the metabolism, homeostasis, and cross-talk of these elements. While much effort has been made in exploring the ionomic traits relating to plant physiology and nutrition, the use of ionomics in the research of serious diseases is still in progress. In recent years, a number of ionomic studies have been carried out for a variety of complex diseases, which offer theoretical and practical insights into the etiology, early diagnosis, prognosis, and therapy of them. This review aims to give an overview of recent applications of ionomics in the study of complex diseases and discuss the latest advances and future trends in this area. Overall, disease ionomics may provide substantial information for systematic understanding of the properties of the elements and the dynamic network of elements involved in the onset and development of diseases. 相似文献
49.
Kang Zhang Rong‐rong Wang Kai‐rui Zhang Fei Cheng Yu Tian Yi Lin Mi Zhou Pu‐xin Zhu 《Polymer International》2020,69(3):274-279
A series of hyperbranched poly(citric polyethylene glycol) (PCPEG) materials with varied polyethylene glycol (PEG) chain lengths as plasticizers were mixed with maize starch (MS) via cooking and film‐forming. The structure, pasting property, plasticization, aging property, moisture absorption and compatibility of plasticized starches were studied by means of Fourier transform infrared spectroscopy, X‐ray diffraction, rapid viscosity analysis, tension testing, moisture absorption measurements and scanning electron microscopy. Compared with PEG and citric acid, PCPEG was more effective in promoting starch chain movement and inhibiting the retrogradation of starch film. Also, PCPEG/MS had smaller moisture content. The longer the plasticizer chain, the better were the aging resistance and moisture resistance of starch. But with an increase of PEG chain length, mechanical properties of PCPEG/MS deteriorated and the compatibility between PCPEG and MS decreased. The hyperbranched derivative of PEG with longer chain exhibited improved plasticization and compatibility with starch. © 2019 Society of Chemical Industry 相似文献
50.
Chaoxin Li Yi Zhou Yuming Tian Yuanyuan Zhao Kaiyue Wang Guomin Li Yuesheng Chai 《Ceramics International》2019,45(5):5613-5616
Ceramics with mullite whiskers were prepared from coal fly ash and Al2O3 raw materials, with AlF3 used as an additive. The phase structures and microstructures of the ceramics were identified via X-ray diffraction and scanning electron microscopy, respectively. The results show that pickling of coal fly ash is an effective method for enhancing the flexural strength of ceramics. Sintering temperature and AlF3 addition were also key factors influencing the creation of ideal ceramics. The ceramic made from pickled coal fly ash, 6?wt% AlF3, and sintered at 1200?°C, exhibited the highest flexural strength of 59.1?MPa, and had a bulk density of 1.32?g/cm3 and porosity of 26.8%. The results show that ceramic materials made under these conditions are ideal candidates for manufacturing ceramic proppants for the exploitation of unconventional oil and gas resources. 相似文献