全文获取类型
收费全文 | 89544篇 |
免费 | 691篇 |
国内免费 | 413篇 |
专业分类
化学 | 31353篇 |
晶体学 | 963篇 |
力学 | 7061篇 |
数学 | 32877篇 |
物理学 | 18394篇 |
出版年
2023年 | 114篇 |
2022年 | 208篇 |
2021年 | 206篇 |
2020年 | 223篇 |
2019年 | 315篇 |
2018年 | 10593篇 |
2017年 | 10441篇 |
2016年 | 6427篇 |
2015年 | 1101篇 |
2014年 | 769篇 |
2013年 | 1252篇 |
2012年 | 4405篇 |
2011年 | 11245篇 |
2010年 | 6102篇 |
2009年 | 6467篇 |
2008年 | 7113篇 |
2007年 | 9247篇 |
2006年 | 674篇 |
2005年 | 1711篇 |
2004年 | 1834篇 |
2003年 | 2181篇 |
2002年 | 1257篇 |
2001年 | 400篇 |
2000年 | 438篇 |
1999年 | 250篇 |
1998年 | 270篇 |
1997年 | 225篇 |
1996年 | 321篇 |
1995年 | 238篇 |
1994年 | 188篇 |
1993年 | 201篇 |
1992年 | 192篇 |
1991年 | 158篇 |
1990年 | 138篇 |
1989年 | 159篇 |
1988年 | 163篇 |
1987年 | 166篇 |
1986年 | 143篇 |
1985年 | 171篇 |
1984年 | 177篇 |
1983年 | 142篇 |
1982年 | 151篇 |
1981年 | 148篇 |
1980年 | 179篇 |
1979年 | 150篇 |
1978年 | 155篇 |
1977年 | 116篇 |
1976年 | 89篇 |
1975年 | 95篇 |
1974年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
S. V. Panin I. V. Vlasov V. P. Sergeev B. B. Ovechkin P. O. Marushchak Sunder Ramasubbu P. S. Lyubutin V. V. Titkov 《Physical Mesomechanics》2015,18(3):261-272
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method. 相似文献
12.
He Haidong Yang Haifeng Zhou Longpeng Chen Tianchi 《Journal of Russian Laser Research》2015,36(3):292-299
Ni–Co alloys have a wide range of applications in various fields owning to their excellent physical, chemical, and mechanical properties. In this paper, we prepare Ni–Co alloy coatings on 316L stain steel surfaces by electroplating. We present a novel approach utilizing a nanosecond laser to induce microtextures on Ni–Co alloy coatings. We study experimentally the effects of laser power and scanning rate on the surface morphologies of Ni–Co alloy coatings. The results indicate that the shape and size of induced microtextures can be controlled by the laser power and scanning rate. The size of grains increases with increase in the work current of the laser (WCL) at a certain scanning rate. With the WCL constant, the size of grains decreases with increase in scanning rate while their average height increases. It is a simple and easily-controlled method for the fabrication of microstructures on Ni–Co alloy coatings, which has promising applications in investigations of the properties of microtextured surfaces, such as friction, adhesion, and wetting. 相似文献
13.
14.
15.
16.
Zenon Moszner 《Aequationes Mathematicae》2018,92(4):617-625
We give the form of the output function in Ginsburg’s machine in which the input and output dictionaries are abelian groups and the transition function is of a special form. 相似文献
17.
18.
Savita Verma Deepak M. Maher Samadhan S. Nagane Bhausaheb V. Tawade Prakash P. Wadgaonkar 《Journal of polymer science. Part A, Polymer chemistry》2019,57(5):588-597
New aromatic (co)polyesters containing pendant propargyloxy groups were synthesized by phase transfer‐catalyzed interfacial polycondensation of 5‐(propargyloxy)isophthaloyl chloride (P‐IPC) and various compositions of P‐IPC and isophthaloyl chloride with bisphenol A. FTIR and NMR spectroscopic data, respectively, revealed successful incorporation of pendant propargyloxy groups into (co)polyesters and formation of (co)polyesters with desired compositions. (Co)polyesters exhibited good solubility in common organic solvents such as chloroform, dichloromethane, and tetrahydrofuran and could be cast into transparent, flexible, and tough films from chloroform solution. Inherent viscosities and number average molecular weights of (co)polyesters were in the range 0.77–1.33 dL/g and 43,600–118,000 g/mol, respectively, indicating the achievement of reasonably high‐molecular weights. The 10% weight loss temperatures of (co)polyesters were in the range 390–420 °C, demonstrating their good thermal stability. (Co)polyesters exhibited Tg in the range 146–170 °C and Tg values decreased with increase in mol % incorporation of P‐IPC. The study of non‐isothermal curing by DSC indicated thermal crosslinking of (co)polyesters via propargyloxy groups. The utility of pendant propargyloxy group was demonstrated by post‐modification of the selected copolyester with 1‐(4‐azidobutyl)pyrene, 9‐(azidomethyl)anthracene, and azido‐terminated poly(ethyleneglycol) monomethyl ether via copper(I)‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction. FTIR and 1H NMR spectra confirmed that click reaction was quantitative. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 588–597 相似文献
19.
Research on Chemical Intermediates - Recorded IR and Raman spectra of 5-fluoro-uracil have been analyzed with the carried out theoretical computation by Gaussian-09 [DFT/B3LYP/6-311?++G**]... 相似文献
20.