全文获取类型
收费全文 | 35230篇 |
免费 | 2241篇 |
国内免费 | 30篇 |
专业分类
电工技术 | 247篇 |
综合类 | 17篇 |
化学工业 | 7513篇 |
金属工艺 | 665篇 |
机械仪表 | 715篇 |
建筑科学 | 988篇 |
矿业工程 | 74篇 |
能源动力 | 686篇 |
轻工业 | 6214篇 |
水利工程 | 329篇 |
石油天然气 | 135篇 |
武器工业 | 5篇 |
无线电 | 1290篇 |
一般工业技术 | 5807篇 |
冶金工业 | 8003篇 |
原子能技术 | 143篇 |
自动化技术 | 4670篇 |
出版年
2024年 | 79篇 |
2023年 | 324篇 |
2022年 | 434篇 |
2021年 | 889篇 |
2020年 | 728篇 |
2019年 | 823篇 |
2018年 | 1398篇 |
2017年 | 1338篇 |
2016年 | 1417篇 |
2015年 | 1098篇 |
2014年 | 1323篇 |
2013年 | 2726篇 |
2012年 | 2077篇 |
2011年 | 1926篇 |
2010年 | 1582篇 |
2009年 | 1428篇 |
2008年 | 1386篇 |
2007年 | 1308篇 |
2006年 | 896篇 |
2005年 | 775篇 |
2004年 | 710篇 |
2003年 | 630篇 |
2002年 | 630篇 |
2001年 | 472篇 |
2000年 | 440篇 |
1999年 | 476篇 |
1998年 | 2411篇 |
1997年 | 1652篇 |
1996年 | 1046篇 |
1995年 | 637篇 |
1994年 | 483篇 |
1993年 | 571篇 |
1992年 | 207篇 |
1991年 | 209篇 |
1990年 | 158篇 |
1989年 | 167篇 |
1988年 | 165篇 |
1987年 | 145篇 |
1986年 | 119篇 |
1985年 | 144篇 |
1984年 | 124篇 |
1983年 | 94篇 |
1982年 | 135篇 |
1981年 | 145篇 |
1980年 | 156篇 |
1979年 | 78篇 |
1978年 | 83篇 |
1977年 | 278篇 |
1976年 | 622篇 |
1973年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Cecilia Arriagada Viviana A. Cavieres Charlotte Luchsinger Alexis E. Gonzlez Vanessa C. Muoz Jorge Cancino Patricia V. Burgos Gonzalo A. Mardones 《International journal of molecular sciences》2020,21(22)
Protein trafficking is altered when normal cells acquire a tumor phenotype. A key subcellular compartment in regulating protein trafficking is the Golgi apparatus, but its role in carcinogenesis is still not well defined. Golgi phosphoprotein 3 (GOLPH3), a peripheral membrane protein mostly localized at the trans-Golgi network, is overexpressed in several tumor types including glioblastoma multiforme (GBM), the most lethal primary brain tumor. Moreover, GOLPH3 is currently considered an oncoprotein, however its precise function in GBM is not fully understood. Here, we analyzed in T98G cells of GBM, which express high levels of epidermal growth factor receptor (EGFR), the effect of stable RNAi-mediated knockdown of GOLPH3. We found that silencing GOLPH3 caused a significant reduction in the proliferation of T98G cells and an unexpected increase in total EGFR levels, even at the cell surface, which was however less prone to ligand-induced autophosphorylation. Furthermore, silencing GOLPH3 decreased EGFR sialylation and fucosylation, which correlated with delayed ligand-induced EGFR downregulation and its accumulation at endo-lysosomal compartments. Finally, we found that EGF failed at promoting EGFR ubiquitylation when the levels of GOLPH3 were reduced. Altogether, our results show that GOLPH3 in T98G cells regulates the endocytic trafficking and activation of EGFR likely by affecting its extent of glycosylation and ubiquitylation. 相似文献
42.
László Lőrincz Máté Zsemberi György Bánsághi Tamás Sohajda Edit Székely 《化学工程与技术》2018,41(7):1466-1472
Chiral molecules, especially enantiomers and diastereomers of purity > 99 %, present a significant market share within the chemical, pharmaceutical, and flavor industries. Antisolvent precipitations, both batch and semicontinuous operations to serve the current trends in flow chemistry were demonstrated to be environmentally benign and efficient tools in achieving high optical purities. Although salts are known to be insoluble in supercritical CO2, instabilities of the nascent salts were detected and applied for increasing efficiency. Diastereomeric excess values of the crystalline products exceeded 99 % in maximum of three consecutive steps both by repeated resolution with half molar equivalent of the amine to the acid and by direct recrystallization of the salts. 相似文献
43.
Abraham G. Alvarado Rosaura Hernández-Montelongo Martin Rabelero Lourdes A. Pérez-Carrillo Jorge E. Puig Francisco López-Serrano 《Polymer Engineering and Science》2020,60(2):223-232
A simple but comprehensive model considering homogeneous and micellar nucleation, coagulation, entry of radicals to particles and to micelles and radicals' exit from particles, is presented. The model is validated, in a starved semicontinuous heterophase polymerization of ethyl methacrylate, at three monomer addition rates. The model accurately describes the overall and instantaneous conversion, the average particle density and diameter, and the number and weight average molar masses evolutions over time. It is found that even though the average number of radicals is much smaller than 0.5, the system is not 0-1. An empirical function was used to describe the gel effect. The homogeneous nucleation was the prevailing mechanism for particle formation and large exit rates of radicals were observed. POLYM. ENG. SCI., 60: 223–232, 2019. © 2019 Society of Plastics Engineers 相似文献
44.
45.
46.
47.
High‐intensity sweeteners in espresso coffee: ideal and equivalent sweetness and time–intensity analysis 下载免费PDF全文
Bruna M. Azevedo Flávio L. Schmidt Helena M. A. Bolini 《International Journal of Food Science & Technology》2015,50(6):1374-1381
The efficient substitution of sucrose by a sweetener in beverages requires the application of some sensory techniques. First, one must determine the concentrations of the sweeteners under study, equivalent in sweetness to the ideal sucrose concentration. In addition, it is fundamental to determine which is most similar to sucrose. The objectives of this study were to determine the ideal sweetness for espresso coffee and the equivalent concentrations in sweetness of different sweeteners, as well as characterise the time–intensity profile of each sweetener in relation to sweetness. The sweeteners evaluated were sucralose, aspartame, neotame, a cyclamate/saccharin mixture (2:1) and stevia. The sucrose concentration considered ideal by consumers was 12.5% (w/v), and the equivalent concentrations of the sweeteners were 0.0159% for sucralose, 0.0549% for aspartame, 0.0016% for neotame, 0.0359% for the cyclamate/saccharin mixture and 0.0998% for stevia. The time–intensity analysis indicated that possibly the sweeteners neotame, aspartame and sucralose would be the best substitutes for sucrose. 相似文献
48.
49.
Hierarchical micro-nanostructured albite-based glass-ceramic for high dielectric strength insulators
V. Fuertes M.J. Cabrera J. Seores D. Muñoz J.F. Fernández E. Enríquez 《Journal of the European Ceramic Society》2018,38(7):2759-2766
A novel glass-ceramic material based on albite type Na-rich feldspar has been synthesized by conventional ceramic process. High crystallinity, >94%?Vol.% is obtained by fast sintering which allows energy saving processing. Albite is the main crystalline phase and tetragonal SiO2 is a secondary phase. Electrical properties were examined by complex impedance, DC measurements, and dielectric breakdown test. Dielectric characterization shows a non-Debye type dielectric behavior with low dielectric constant, 4.6 at 1?MHz, low dielectric losses, (~10?3 at 1?MHz, and a large dielectric strength, ~60?kV/mm), that it is the largest value reported in ceramic insulators. Those dielectric properties are attained by the low glassy phase content in the samples and their unique micro-nanostructure. All these properties make this novel material a very promising candidate in the market of ceramic electrical insulator, highlighting for high-voltage applications. 相似文献
50.
Crespo Juan-José Sánchez José L. Alfaro-Cortés Francisco J. Flich José Duato José 《The Journal of supercomputing》2021,77(11):12826-12856
The Journal of Supercomputing - Deadlock-free dynamic network reconfiguration process is usually studied from the routing algorithm restrictions and resource reservation perspective. The dynamic... 相似文献