全文获取类型
收费全文 | 696171篇 |
免费 | 9388篇 |
国内免费 | 1649篇 |
专业分类
电工技术 | 12344篇 |
综合类 | 601篇 |
化学工业 | 106333篇 |
金属工艺 | 30545篇 |
机械仪表 | 22304篇 |
建筑科学 | 15743篇 |
矿业工程 | 5057篇 |
能源动力 | 17181篇 |
轻工业 | 53191篇 |
水利工程 | 8201篇 |
石油天然气 | 18037篇 |
武器工业 | 50篇 |
无线电 | 73122篇 |
一般工业技术 | 145136篇 |
冶金工业 | 125659篇 |
原子能技术 | 17764篇 |
自动化技术 | 55940篇 |
出版年
2021年 | 6695篇 |
2020年 | 4907篇 |
2019年 | 6376篇 |
2018年 | 11345篇 |
2017年 | 11338篇 |
2016年 | 11901篇 |
2015年 | 7621篇 |
2014年 | 12753篇 |
2013年 | 31072篇 |
2012年 | 19513篇 |
2011年 | 26155篇 |
2010年 | 20718篇 |
2009年 | 23219篇 |
2008年 | 23696篇 |
2007年 | 23144篇 |
2006年 | 19712篇 |
2005年 | 17924篇 |
2004年 | 17355篇 |
2003年 | 17113篇 |
2002年 | 16181篇 |
2001年 | 16229篇 |
2000年 | 15236篇 |
1999年 | 15478篇 |
1998年 | 37707篇 |
1997年 | 26932篇 |
1996年 | 20535篇 |
1995年 | 15645篇 |
1994年 | 13743篇 |
1993年 | 13613篇 |
1992年 | 10166篇 |
1991年 | 9768篇 |
1990年 | 9741篇 |
1989年 | 9389篇 |
1988年 | 8759篇 |
1987年 | 8050篇 |
1986年 | 7854篇 |
1985年 | 8621篇 |
1984年 | 8158篇 |
1983年 | 7416篇 |
1982年 | 6947篇 |
1981年 | 7118篇 |
1980年 | 6864篇 |
1979年 | 6902篇 |
1978年 | 6878篇 |
1977年 | 7781篇 |
1976年 | 9760篇 |
1975年 | 6064篇 |
1974年 | 5908篇 |
1973年 | 5984篇 |
1972年 | 5116篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Russian Engineering Research - The modernization of manufacturing by the comprehensive application of digital technology—in both production and management—is considered. Principles are... 相似文献
63.
Belov M. I. Anashin D. V. Kabdin N. E. Storchevoy V. F. Sudnik Yu. A. 《Russian Engineering Research》2022,42(11):1110-1116
Russian Engineering Research - The stability of robot-mower motion in a specific direction is considered. The direction is regulated by means of an angular sensor and a programmable controller... 相似文献
64.
Revin A. A. Mikhaylova A. M. Konakov A. A. Tsyplenkov V. V. Shastin V. N. 《Semiconductors》2021,55(12):879-884
Semiconductors - The wave functions of electrons localized at P, As, and Sb shallow donors in Ge are calculated in the envelope function approximation taking into account valley–orbit... 相似文献
65.
Yang Hu Stephanie M. Sjoberg Chunpen Chen Amber L. Hauvermale Craig F. Morris Stephen R. Delwiche Ashley E. Cannon Camille M. Steber Zhiwu Zhang 《Comprehensive Reviews in Food Science and Food Safety》2022,21(3):2105-2117
This review examines the application, limitations, and potential alternatives to the Hagberg–Perten falling number (FN) method used in the global wheat industry for detecting the risk of poor end-product quality mainly due to starch degradation by the enzyme α-amylase. By viscometry, the FN test indirectly detects the presence of α-amylase, the primary enzyme that digests starch. Elevated α-amylase results in low FN and damages wheat product quality resulting in cakes that fall, and sticky bread and noodles. Low FN can occur from preharvest sprouting (PHS) and late maturity α-amylase (LMA). Moist or rainy conditions before harvest cause PHS on the mother plant. Continuously cool or fluctuating temperatures during the grain filling stage cause LMA. Due to the expression of additional hydrolytic enzymes, PHS has a stronger negative impact than LMA. Wheat grain with low FN/high α-amylase results in serious losses for farmers, traders, millers, and bakers worldwide. Although blending of low FN grain with sound wheat may be used as a means of moving affected grain through the marketplace, care must be taken to avoid grain lots from falling below contract-specified FN. A large amount of sound wheat can be ruined if mixed with a small amount of sprouted wheat. The FN method is widely employed to detect α-amylase after harvest. However, it has several limitations, including sampling variability, high cost, labor intensiveness, the destructive nature of the test, and an inability to differentiate between LMA and PHS. Faster, cheaper, and more accurate alternatives could improve breeding for resistance to PHS and LMA and could preserve the value of wheat grain by avoiding inadvertent mixing of high- and low-FN grain by enabling testing at more stages of the value stream including at harvest, delivery, transport, storage, and milling. Alternatives to the FN method explored here include the Rapid Visco Analyzer, enzyme assays, immunoassays, near-infrared spectroscopy, and hyperspectral imaging. 相似文献
66.
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
67.
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
68.
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
69.
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
70.
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