全文获取类型
收费全文 | 802526篇 |
免费 | 11772篇 |
国内免费 | 2426篇 |
专业分类
电工技术 | 14677篇 |
综合类 | 746篇 |
化学工业 | 120475篇 |
金属工艺 | 30791篇 |
机械仪表 | 24301篇 |
建筑科学 | 18820篇 |
矿业工程 | 3940篇 |
能源动力 | 22266篇 |
轻工业 | 65054篇 |
水利工程 | 8198篇 |
石油天然气 | 14365篇 |
武器工业 | 48篇 |
无线电 | 93211篇 |
一般工业技术 | 157932篇 |
冶金工业 | 156705篇 |
原子能技术 | 16304篇 |
自动化技术 | 68891篇 |
出版年
2022年 | 4897篇 |
2021年 | 7472篇 |
2020年 | 5572篇 |
2019年 | 7041篇 |
2018年 | 11987篇 |
2017年 | 11781篇 |
2016年 | 12491篇 |
2015年 | 8413篇 |
2014年 | 13875篇 |
2013年 | 38111篇 |
2012年 | 21930篇 |
2011年 | 30147篇 |
2010年 | 23867篇 |
2009年 | 26935篇 |
2008年 | 27396篇 |
2007年 | 27131篇 |
2006年 | 23890篇 |
2005年 | 21652篇 |
2004年 | 20709篇 |
2003年 | 20545篇 |
2002年 | 19351篇 |
2001年 | 19311篇 |
2000年 | 18013篇 |
1999年 | 19063篇 |
1998年 | 48985篇 |
1997年 | 34318篇 |
1996年 | 26346篇 |
1995年 | 19713篇 |
1994年 | 17153篇 |
1993年 | 16969篇 |
1992年 | 12233篇 |
1991年 | 11403篇 |
1990年 | 11328篇 |
1989年 | 10887篇 |
1988年 | 10067篇 |
1987年 | 9037篇 |
1986年 | 8834篇 |
1985年 | 9831篇 |
1984年 | 9090篇 |
1983年 | 8137篇 |
1982年 | 7574篇 |
1981年 | 7692篇 |
1980年 | 7230篇 |
1979年 | 7077篇 |
1978年 | 6879篇 |
1977年 | 8155篇 |
1976年 | 10694篇 |
1975年 | 5936篇 |
1974年 | 5555篇 |
1973年 | 5718篇 |
排序方式: 共有10000条查询结果,搜索用时 38 毫秒
71.
Kumar S. Ganesh Sridhar S. S. Hussain Azham Manikanthan S. V. Padmapriya T. 《Multimedia Tools and Applications》2022,81(7):9091-9109
Multimedia Tools and Applications - Discovering the relevant web services for specific applications in the dynamically changing business world becomes very critical. Researchers have used many... 相似文献
72.
Mohammed Amin Salih Venkatachalam K. Hubálovský S. Trojovský P. Prabu P. 《Mobile Networks and Applications》2022,27(3):1050-1059
Mobile Networks and Applications - 5G/6G communication are first generation high speed wireless communication network which integrates the aerial data, terrestrial data and maritime data via... 相似文献
73.
Kruglikov S. S. Zagorskii D. L. Kolesnikov V. A. Doludenko I. M. Bedin S. A. 《Theoretical Foundations of Chemical Engineering》2021,55(5):942-951
Theoretical Foundations of Chemical Engineering - The effect of the electrolyte composition, mass-transfer conditions, pore diameter, interpore distance, and electric parameters on the formation of... 相似文献
74.
Vasanthapriya R. Neelakandeswari N. Uthayarani K. Chitra M. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(11):4272-4280
Journal of Inorganic and Organometallic Polymers and Materials - This paper reports the performance of alizarin based SnO2 dye-sensitized solar cells. A novel template assisted method has been... 相似文献
75.
Applied Composite Materials - Determining the impact behavior of adhesive joints allows the designing of high-strength joints. Therefore, the dynamic behavior of adhesive joints has recently become... 相似文献
76.
Vancha Harish Effi Haque Magdalena
miech Hiroaki Taniguchi Sarah Jamieson Devesh Tewari Anupam Bishayee 《International journal of molecular sciences》2021,22(9)
Xanthohumol (XH) is an important prenylated flavonoid that is found within the inflorescence of Humulus lupulus L. (Hop plant). XH is an important ingredient in beer and is considered a significant bioactive agent due to its diverse medicinal applications, which include anti-inflammatory, antimicrobial, antioxidant, immunomodulatory, antiviral, antifungal, antigenotoxic, antiangiogenic, and antimalarial effects as well as strong anticancer activity towards various types of cancer cells. XH acts as a wide ranging chemopreventive and anticancer agent, and its isomer, 8-prenylnaringenin, is a phytoestrogen with strong estrogenic activity. The present review focuses on the bioactivity of XH on various types of cancers and its pharmacokinetics. In this paper, we first highlight, in brief, the history and use of hops and then the chemistry and structure–activity relationship of XH. Lastly, we focus on its prominent effects and mechanisms of action on various cancers and its possible use in cancer prevention and treatment. Considering the limited number of available reviews on this subject, our goal is to provide a complete and detailed understanding of the anticancer effects of XH against different cancers. 相似文献
77.
L.J. Espinoza-Pérez S. Esquivel-Medina E. López-Honorato 《Ceramics International》2021,47(11):15527-15532
The influence of the microstructure on the corrosion rate of three monolithic SiC samples in FLiNaK salt at 900 °C for 250 h was studied. The SiC samples, labeled as SiC-1, SiC-2, and SiC-3, had corrosion rates of 0.137, 0.020, and 0.043 mg/cm2h, respectively. Compared with grain size and the presence of special grain boundaries (i.e., Σ3), the content of high-angle grain boundaries (HAGBs) appeared to have the strongest influence on the corrosion rate of SiC in FLiNaK salt, since the corrosion rate increased six times as the concentration of high-angle grain boundaries increased from 19 to 32% for SiC-2 and SiC-1, respectively. These results stress the importance of controlling the content of HAGBs during the production process of SiC. 相似文献
78.
Ebrahim A. Mahdy Khadega M. Sahbal Hanan H. Beherei Yasser K. Abdel-Monem 《Ceramics International》2021,47(5):6251-6261
A new TiO2-containing bioactive glass and glass-ceramics based on 50SiO2-(45-X)CaO-(XTiO2)-5P2O5 system was designed using a sol–gel technique (where X = 5, 7.5 and 10 wt %). The roles of the crystallization behavior and physicochemical characteristics of the designed glass and glass-ceramics which were played in the introduction of TiO2 substitutions were investigated. Moreover, cell proliferation and differentiation were evaluated against human osteosarcoma cells (Saos-2). The TiO2/CaO replacements led to the formation of a stronger glass structure and thus increased thermal parameters and the chemical stabilization of the designed materials. The FTIR data confirmed the existence of Ti within the glass and glass-ceramics samples, and no remarkable effect on their chemical integrity was observed. The XRD patterns indicated that calcium-containing minerals, including Ca2SiO4,Ca3(PO4)2, Ca(Ti,Si)O5, CaTiSiO5, and Ca15(PO4)2·(SiO4)6 phases were developed as a role of structure/texture under the applied heat-treatment. The results of the cytotoxicity test proved that a safe sample dose is 12–50 μg/ml, at which cell viability is ≥ 85%. The cell differentiation determined by ALP test proved the superiority of glass-ceramics compared with their native glasses. Therefore, the obtained materials could be safely used as novel biocompatible materials for the regeneration of bone tissue. 相似文献
79.
T.V. Vakalova L.P. Devyashina Sh.M. Sharafeev N.P. Sergeev 《Ceramics International》2021,47(11):15282-15292
One of the drawbacks of fusible clays is the narrow sintering interval due to a sharp increase in the amount of iron-silicate melt at a temperature of 1000–1100 °C, which hardens in the form of a glass phase upon cooling. This leads to a relatively low mechanical strength of the calcined samples and causes the danger of melting the granular material surface from such clays during the firing process. To increase the strength of samples of fusible clays, the influence of diabase and granitoid rocks was considered. It was found that the strengthening effect of diabase and granitoid rock additives in an amount of 20–50% in a mixture with fusible clay is due to an increase of total content of the crystalline phase (mullite, cristobalite and residual quartz) from 18–20% in clays without additives to 22–28 % - in mixtures with diabase and to 28–34% - with granitoid additives) at a temperature of 1050–1100 °C. This increase is due to the activation of synthesis processes of secondary mullite and crystallization from alkali-rich feldspar melt of amorphous silica, released from the structure of clay minerals. The established influence of the igneous rocks used made it possible to develop compositions and propose process flow sheet for producing aluminosilicate proppants based on fusible clays. The use of granitoid and diabase rocks in an amount of 20–70% with fusible clays produces lightweight aluminosilicate proppants with bulk density of 1.40–1.46 g/cm3 at temperature range of 1050–1100 °C, which can endure destructive pressures up to 34.5–52 MPa. 相似文献
80.
Andrade R. G. S. A. de Oliveira A. E. Guerra V. G. 《Theoretical Foundations of Chemical Engineering》2022,56(4):504-512
Theoretical Foundations of Chemical Engineering - The corona onset voltage is an important operating parameter in the electrostatic precipitation of nanoparticulate, however, its experimental... 相似文献