全文获取类型
收费全文 | 300364篇 |
免费 | 7101篇 |
国内免费 | 2846篇 |
专业分类
电工技术 | 7374篇 |
技术理论 | 8篇 |
综合类 | 3211篇 |
化学工业 | 44416篇 |
金属工艺 | 12139篇 |
机械仪表 | 10752篇 |
建筑科学 | 9707篇 |
矿业工程 | 2567篇 |
能源动力 | 8638篇 |
轻工业 | 23812篇 |
水利工程 | 2974篇 |
石油天然气 | 7042篇 |
武器工业 | 458篇 |
无线电 | 39449篇 |
一般工业技术 | 55635篇 |
冶金工业 | 50882篇 |
原子能技术 | 5563篇 |
自动化技术 | 25684篇 |
出版年
2022年 | 2672篇 |
2021年 | 4124篇 |
2020年 | 3073篇 |
2019年 | 3195篇 |
2018年 | 4700篇 |
2017年 | 4903篇 |
2016年 | 4810篇 |
2015年 | 4123篇 |
2014年 | 6281篇 |
2013年 | 14309篇 |
2012年 | 9137篇 |
2011年 | 11837篇 |
2010年 | 9649篇 |
2009年 | 10541篇 |
2008年 | 11138篇 |
2007年 | 10785篇 |
2006年 | 9945篇 |
2005年 | 8768篇 |
2004年 | 7697篇 |
2003年 | 7886篇 |
2002年 | 7241篇 |
2001年 | 7600篇 |
2000年 | 7170篇 |
1999年 | 7800篇 |
1998年 | 17573篇 |
1997年 | 12341篇 |
1996年 | 9623篇 |
1995年 | 7354篇 |
1994年 | 6517篇 |
1993年 | 6306篇 |
1992年 | 4485篇 |
1991年 | 4277篇 |
1990年 | 4067篇 |
1989年 | 3795篇 |
1988年 | 3689篇 |
1987年 | 3097篇 |
1986年 | 2997篇 |
1985年 | 3235篇 |
1984年 | 2951篇 |
1983年 | 2851篇 |
1982年 | 2658篇 |
1981年 | 2556篇 |
1980年 | 2472篇 |
1979年 | 2309篇 |
1978年 | 2108篇 |
1977年 | 2604篇 |
1976年 | 3562篇 |
1975年 | 1764篇 |
1974年 | 1729篇 |
1973年 | 1665篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
61.
双检合并技术在海底电缆地震资料处理中被广泛应用,可衰减电缆鬼波的影响。传统方式以水、陆检记录的波场记录相同为假设,电缆鬼波压制效果差,合并效果并不理想。在分析交叉鬼波化双检合并技术基本原理的基础上,综合利用水检资料与陆检鬼波褶积的结果和陆检资料与水检鬼波褶积的结果求取刻度算子,同时在地震资料处理中利用陆检资料标定水检资料,从而优化了交叉鬼波化双检合并技术。实际资料处理结果表明,改进后的技术可有效衰减电缆鬼波,分离出上行波场,大幅度拓宽地震资料频带,提高地震资料分辨率,从而提供更丰富的构造细节信息。 相似文献
62.
63.
64.
Semiconductors - We found bulk n-GaAs layers grown by liquid phase epitaxy to be irregularly stressed. Deformation created by this stress causes a small but detectable quadrupole splitting of... 相似文献
65.
Kolmachikhina E. B. Sviridov A.V. Naumov K. D. 《Russian Journal of Non-Ferrous Metals》2020,61(5):488-493
Russian Journal of Non-Ferrous Metals - This article is devoted to the influence of sodium lignosulfonate (SL), anionic surfactants (sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate... 相似文献
66.
Madhu H. C. Edachery Vimal Lijesh K. P. Perugu Chandra Shekhar Kailas Satish V. 《Metallurgical and Materials Transactions A》2020,51(8):4086-4099
Metallurgical and Materials Transactions A - Hybrid nanocomposites have potential as wear-resistant materials. However, synthesizing these nanocomposites by conventional molten state methods result... 相似文献
67.
Weikang Dong Ruishi Qi Tiansheng Liu Yi Li Ning Li Ze Hua Zirui Gao Shuyuan Zhang Kaihui Liu Jiandong Guo Peng Gao 《Advanced materials (Deerfield Beach, Fla.)》2020,32(46):2002014
Hyperbolic phonon polaritons (HPhPs) in orthorhombic-phase molybdenum trioxide (α-MoO3) show in-plane hyperbolicity, great wavelength compression, and ultralong lifetime, therefore holding great potential in nanophotonic applications. However, its polaritonic response in the far-infrared (FIR) range remains unexplored due to challenges in experimental characterization. Here, monochromated electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) is used to probe HPhPs in α-MoO3 in both mid-infrared (MIR) and FIR frequencies and correlate their behaviors with microstructures and orientations. It is found that low structural symmetry leads to various phonon modes and multiple Reststrahlen bands (RBs) over a broad spectral range (over 70 meV) and in different directions (55–63 meV and 119–125 meV along the b-axis, 68–106 meV along the c-axis, and 101–121 meV along the a-axis). These HPhPs can be selectively excited by controlling the direction of swift electrons. These findings provide new opportunities in nanophotonic and optoelectronic applications, such as directed light propagation, hyperlenses, and heat transfer. 相似文献
68.
Manoj Karakoti Ritu Jangra Sandeep Pandey Pawan Singh Dhapola Sunil Dhali Suman Mahendia Pramod K Singh Nanda Gopal Sahoo 《International Journal of Applied Ceramic Technology》2020,17(4):1899-1908
This study deals with the utility of mini spray dryer process to improve the dispersibility, of graphene oxide(GO) and its application for high-performance supercapacitor. Initially, the neutral solution of GO was obtained using the modified Hummer's method. After this, the prepared GO solution was processed by mini spray dryer to obtain a more purified, lighter, and dispersed form of GO which is named as spray dryer processed GO (SPGO). The SPGO thus obtained showed excellent dispersibility behavior with various solvents, which is not found in case of conventional oven drying. Furthermore, utility of SPGO and its reduced form (r-SPGO) for supercapacitor applications have been investigated. Results obtained from the cyclic voltammetry(CV) analysis, impedance, and charge-discharge behavior of supercapacitor fabricated using r-SPGO shows enhanced features. Therefore, the simple spray dried GO and its reduced form, that is, r-SPGO can be utilized as a potential candidate for the supercapacitor application. Herein, as synthesized SPGO exhibited the specific capacitance of 12.07 and 37.6 F/g with PVA-H3PO4 and 1 mol/L H3PO4, respectively, at a scan rate of 5 mV/s. On the other hand, reduced form of SPGO, that is, r-SPGO showed the specific capacitance of 27.16 and 230 F/g with PVA-H3PO4 and 1 mol/L H3PO4, respectively. 相似文献
69.
Konstantinos Spyrou Matteo Calvaresi Evmorfia K. Diamanti Theodoros Tsoufis Dimitrios Gournis Petra Rudolf Francesco Zerbetto 《Advanced functional materials》2015,25(2):263-269
Experimental and theoretical studies are performed in order to illuminate, for first time, the intercalation mechanism of polycyclic aromatic molecules into graphite oxide. Two representative molecules of this family, aniline and naphthalene amine are investigated. After intercalation, aniline molecules prefer to covalently connect to the graphene oxide matrix via chemical grafting, while napthalene amine molecules bind with the graphene oxide surface through π–π interactions. The presence of intercalated aromatic molecules between the graphene oxide layers is demonstrated by X‐ray diffraction, while the type of interaction between graphene oxide and polycyclic organic molecules is elucidated by X‐ray photoelectron spectroscopy. Combined quantum mechanical and molecular mechanical calculations describe the intercalation mechanism and the aniline grafting, rationalizing the experimental data. The present work opens new perspectives for the interaction of various aromatic molecules with graphite oxide and the so‐called “intercalation chemistry”. 相似文献
70.