全文获取类型
收费全文 | 102446篇 |
免费 | 1432篇 |
国内免费 | 472篇 |
专业分类
化学 | 40091篇 |
晶体学 | 941篇 |
力学 | 7217篇 |
数学 | 35967篇 |
物理学 | 20134篇 |
出版年
2023年 | 172篇 |
2022年 | 219篇 |
2021年 | 357篇 |
2020年 | 473篇 |
2019年 | 483篇 |
2018年 | 10648篇 |
2017年 | 10502篇 |
2016年 | 6909篇 |
2015年 | 1608篇 |
2014年 | 1187篇 |
2013年 | 1969篇 |
2012年 | 5127篇 |
2011年 | 11979篇 |
2010年 | 6535篇 |
2009年 | 6802篇 |
2008年 | 7701篇 |
2007年 | 9791篇 |
2006年 | 1267篇 |
2005年 | 2218篇 |
2004年 | 2342篇 |
2003年 | 2664篇 |
2002年 | 1694篇 |
2001年 | 641篇 |
2000年 | 646篇 |
1999年 | 512篇 |
1998年 | 516篇 |
1997年 | 461篇 |
1996年 | 540篇 |
1995年 | 442篇 |
1994年 | 361篇 |
1993年 | 371篇 |
1992年 | 325篇 |
1991年 | 303篇 |
1990年 | 277篇 |
1989年 | 292篇 |
1988年 | 273篇 |
1987年 | 252篇 |
1986年 | 237篇 |
1985年 | 298篇 |
1984年 | 286篇 |
1983年 | 238篇 |
1982年 | 262篇 |
1981年 | 265篇 |
1980年 | 261篇 |
1979年 | 258篇 |
1978年 | 271篇 |
1977年 | 216篇 |
1976年 | 180篇 |
1975年 | 184篇 |
1973年 | 177篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
A protocol to correct for intra‐ and interspecific variation in tail hair growth to align isotope signatures of segmentally cut tail hair to a common time line
下载免费PDF全文
![点击此处可从《Rapid communications in mass spectrometry : RCM》网站下载免费的PDF全文](/ch/ext_images/free.gif)
22.
Formation of porous polymer morphology by microsyneresis during divinylbenzene polymerization
下载免费PDF全文
![点击此处可从《Journal of Polymer Science.Polymer Physics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Libuše Hanková Ladislav Holub Karel Jeřábek 《Journal of Polymer Science.Polymer Physics》2015,53(11):774-781
This article describes the investigation of the importance of various reaction conditions on microsyneretic pore formation during polymerization of divinylbenzene (DVB) under so‐called “solvothermal” conditions. To induce microsyneretic pore formation, the most important parameter is an unusually high dilution of monomers with a “good” porogen solvating the polymer chains. High dilution and solvation of the growing poly(DVB) chains promote the prolongation of the polymer chains rather than their interconnection by crosslinking. Consequently, when the polymer gel density reaches the point where syneresis starts, the polymer network is geometrically too extensive to be broken up into precipitating entities and, instead, porogen droplets are formed within the continuous polymer gel. The pore geometry created by microsyneresis offers high surface area in wide mesopores and hence, high capacity for supporting functional groups or reactions with much better accessibility than narrow pores between polymer microspheres produced by macrosyneresis in conventional styrenic polymer supports. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 774–781 相似文献
23.
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
24.
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
25.
26.
27.
28.
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
29.
30.