全文获取类型
收费全文 | 209058篇 |
免费 | 10062篇 |
国内免费 | 5615篇 |
专业分类
电工技术 | 7745篇 |
技术理论 | 6篇 |
综合类 | 6407篇 |
化学工业 | 27924篇 |
金属工艺 | 12070篇 |
机械仪表 | 10406篇 |
建筑科学 | 10373篇 |
矿业工程 | 3569篇 |
能源动力 | 6117篇 |
轻工业 | 12689篇 |
水利工程 | 2418篇 |
石油天然气 | 8024篇 |
武器工业 | 821篇 |
无线电 | 27763篇 |
一般工业技术 | 34880篇 |
冶金工业 | 31347篇 |
原子能技术 | 2469篇 |
自动化技术 | 19707篇 |
出版年
2024年 | 508篇 |
2023年 | 2030篇 |
2022年 | 3606篇 |
2021年 | 4990篇 |
2020年 | 3879篇 |
2019年 | 3424篇 |
2018年 | 4128篇 |
2017年 | 4487篇 |
2016年 | 4342篇 |
2015年 | 5124篇 |
2014年 | 6506篇 |
2013年 | 10960篇 |
2012年 | 9094篇 |
2011年 | 10896篇 |
2010年 | 9141篇 |
2009年 | 9629篇 |
2008年 | 9584篇 |
2007年 | 9496篇 |
2006年 | 9432篇 |
2005年 | 8318篇 |
2004年 | 6424篇 |
2003年 | 6082篇 |
2002年 | 5545篇 |
2001年 | 5645篇 |
2000年 | 5280篇 |
1999年 | 5946篇 |
1998年 | 12000篇 |
1997年 | 8207篇 |
1996年 | 6737篇 |
1995年 | 4766篇 |
1994年 | 4087篇 |
1993年 | 3590篇 |
1992年 | 2376篇 |
1991年 | 2143篇 |
1990年 | 1956篇 |
1989年 | 1696篇 |
1988年 | 1462篇 |
1987年 | 1051篇 |
1986年 | 1053篇 |
1985年 | 1022篇 |
1984年 | 896篇 |
1983年 | 774篇 |
1982年 | 763篇 |
1981年 | 726篇 |
1980年 | 611篇 |
1979年 | 510篇 |
1978年 | 435篇 |
1977年 | 550篇 |
1976年 | 966篇 |
1975年 | 308篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Spinel LiSr0·1Cr0·1Mn1·8O4 was synthesised by high temperature solid state method in order to enhance the electrochemical performance. The LiSr0·1Cr0·1Mn1·8O4 (LSCMO) materials were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical tests. The XRD and SEM studies confirm that LSCMO had spinel crystal structure with a space group of Fd3m, and the particle of LSCMO shows irregular shape. The cyclic voltammetry data illustrated that the heavy current charge–discharge performance of LMO was improved by Sr2+ and Cr3+ doping. The galvanostatic charge–discharge of LSCMO cathode materials was measured at 1, 5, 10 and 20 C. The results indicated that LSCMO improved the capacity retention. 相似文献
63.
64.
Strength of Materials - A metallographic method, dilatometry, and X-ray diffraction were applied to investigate the effects of undercooling and holding time on bainitic transformation,... 相似文献
65.
E-voting maybe replaces the traditional voting scheme in the future, however, the security threat must be paid enough attention. In this paper, a novel e-voting scheme is proposed using secret sharing and k-anonymity, which not only satisfies the basic security goals such as the non-cheating, the universal verifiability, the confidentiality, and the anonymity, but also achieves the addition properties including coercion-resistance and unconditional security since the security of the proposed scheme does not rely on any computational hard problem.
相似文献66.
D. Kherifi H. Belhouchet S. Ramesh K.Y. Sara Lee A. Kenzour S. Djoualah M.K.G. Abbas Y.H. Wong S. Ramesh 《Ceramics International》2021,47(12):16483-16490
In this work, the sintering behaviour of fluorapatite (FAp)–silicate composites prepared by mixing variable amounts of natural quartz (2.5 wt% to 20 wt%) and FAp was studied. The composites were pressureless sintered in air at temperatures from 1000 °C to 1350 °C. The effects of temperatures on the densification, phase formation, chemical bonding and Vickers hardness of the composites were evaluated. All the samples exhibited mixed phase, comprising FAp and francolite as the major constituents along with some minor phases of cristobalite, wollastonite, dicalcium silicate and/or whitlockite dependent on the quartz content and sintering temperature. The composite containing 2.5 wt% quartz exhibited the best sintering properties. The highest bulk density of 3 g/cm3 and a Vickers hardness of >4.2 GPa were obtained for the 2.5 wt% quartz–FAp composite when sintered at 1100 °C. The addition of quartz was found to alter the microstructure of the composites, where it exhibited a rod-like morphology when sintered at 1000 °C and a regular rounded grain structure when sintered at 1350 °C. A wetted grain surface was observed for composites containing high quartz content and was believed to be associated with a transient liquid phase sintering. 相似文献
67.
Zhang Xi Wang Xianhai Zhao Hongke Ordóñez de Pablos Patricia Sun Yongqiang Xiong Hui 《Scientometrics》2019,119(3):1311-1344
Scientometrics - Altmetrics indices are increasingly applied to measure scholarly influence in recent years because they can reflect the influence of research outputs more timely comparing with... 相似文献
68.
Evangelopoulos Xenophon Brockmeier Austin J. Mu Tingting Goulermas John Y. 《Machine Learning》2019,108(4):595-626
Machine Learning - We propose a set of highly scalable algorithms for the combinatorial data analysis problem of seriating similarity matrices. Seriation consists of finding a permutation of data... 相似文献
69.
Qin-yu Zhou Shan Zhao Yan-yan Huang Jin-shuang Hu Jia-hua Kuang Dong-mei Liu Charles S. Brennan 《International Journal of Food Science & Technology》2021,56(6):2992-3003
Yogurt preserves and enhances nutritional value of milk. In this study, we have compared several strains to determine the physicochemical, sensory, rheological and aroma characteristics of different yogurts. We used Lactobacillus gasseri LGZ 1029 (LG), commercial probiotic L. rhamnosus (LGG) and traditional fermentation strains Streptococcus thermophilus and L. bulgaricus (SL). Results showed that the flavour and texture characteristics of mixed-strain yogurts were obviously better than in single-strain yogurts. Addition of LG increased pseudoplastic behaviour, as shown by Herschel–Bulkley model analysis of rheological behaviour. The LG + SL group also had both the highest viscosity consistency index and thickening ability. In addition, a total of 57 volatile compounds were detected in yogurts and the fermentation with the addition of LG was mainly affected by ketones. Our study suggested that a yogurt with new attributes can be produced by using LGZ 1029. 相似文献
70.
Yuhuan Sun Hongshuang Qin Zhengqing Yan Chuanqi Zhao Jinsong Ren Xiaogang Qu 《Advanced functional materials》2019,29(14)
Recently, quorum sensing (QS) inhibitors (QSIs) have been combined with antibiotics to enhance antibiofilm efficacy in vitro and in vivo. However, targeting QS signals alone is not enough to prevent bacterial infections. Drug resistance and recurrence of biofilms makes it difficult to eradicate. Herein, photodynamic therapy (PDT) is selected to unite QSIs and antibiotics. A synergistically antibiofilm system, which combines QSIs, antibiotics, and PDT based on hollow carbon nitride spheres (HCNSs) is envisaged. First, HCNS provides the multidrug delivering ability, enabling QSIs and antibiotics to be released in sequence. Subsequently, multistage releases sensitize bacteria effectively, potentiating the chemotherapeutic effects of the antibiotics. Finally, the integration of QSIs and PDT not only minimizes the possibility of drug resistance, but also overcomes the problem of limited mass and extension of PDT. Even after 48 h of incubation, the bacterial biofilm is obviously inhibited. And its biofilm disperse efficiency exceeds 48% (compared with QSI‐potentiated chemotherapy group) and 40% (compared with PDT group). Besides, the inhibition of the QS system influences phenotypes related to virulence factor production and surface hydrophobicity, which weaken biofilm invasion and formation. Eventually, this system is applied to disperse bacterial biofilm in vivo. Overall, PDT and QS modulation are devoted to eradicate drug resistance and recurrence of the biofilm. 相似文献