全文获取类型
收费全文 | 158421篇 |
免费 | 2944篇 |
国内免费 | 1430篇 |
专业分类
化学 | 88556篇 |
晶体学 | 2504篇 |
力学 | 6551篇 |
综合类 | 114篇 |
数学 | 15140篇 |
物理学 | 49930篇 |
出版年
2021年 | 1333篇 |
2020年 | 1559篇 |
2019年 | 1620篇 |
2018年 | 1936篇 |
2017年 | 2008篇 |
2016年 | 3086篇 |
2015年 | 2055篇 |
2014年 | 2972篇 |
2013年 | 6884篇 |
2012年 | 5819篇 |
2011年 | 6972篇 |
2010年 | 4861篇 |
2009年 | 4805篇 |
2008年 | 6422篇 |
2007年 | 6109篇 |
2006年 | 5903篇 |
2005年 | 5380篇 |
2004年 | 4842篇 |
2003年 | 4480篇 |
2002年 | 4393篇 |
2001年 | 5842篇 |
2000年 | 4175篇 |
1999年 | 3309篇 |
1998年 | 2265篇 |
1997年 | 2332篇 |
1996年 | 2215篇 |
1995年 | 2025篇 |
1994年 | 2026篇 |
1993年 | 1829篇 |
1992年 | 2307篇 |
1991年 | 2389篇 |
1990年 | 2196篇 |
1989年 | 2166篇 |
1988年 | 2128篇 |
1987年 | 2136篇 |
1986年 | 1959篇 |
1985年 | 2422篇 |
1984年 | 2426篇 |
1983年 | 1937篇 |
1982年 | 1948篇 |
1981年 | 1773篇 |
1980年 | 1757篇 |
1979年 | 2051篇 |
1978年 | 2124篇 |
1977年 | 2070篇 |
1976年 | 2004篇 |
1975年 | 1881篇 |
1974年 | 1867篇 |
1973年 | 1896篇 |
1972年 | 1251篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
21.
22.
The European Physical Journal Special Topics - The removal of suspended particles from the interior of a thermocapillary liquid bridge via a finite-particle-size effect restricting the particle... 相似文献
23.
Nano palladium supported on high‐surface‐area metal–organic framework MIL‐101: an efficient catalyst for Sonogashira coupling of aryl and heteroaryl bromides with alkynes 下载免费PDF全文
Manne Annapurna T. Parsharamulu P. Vishnuvardhan Reddy M. Suresh Pravin R. Likhar Mannepalli Lakshmi Kantam 《应用有机金属化学》2015,29(4):234-239
Palladium nanoparticle‐incorporated metal–organic framework MIL‐101 (Pd/MIL‐101) was successfully synthesized and characterized using X‐ray diffraction, nitrogen physisorption, X‐ray photoelectron, UV–visible and infrared spectroscopies, and transmission electron microscopy. The characterization techniques confirmed high porosity and high surface area of MIL‐101 and high stability of nano‐size palladium particles. Pd/MIL‐101 nanocomposite was investigated for the Sonogashira cross‐coupling reaction of aryl and heteroaryl bromides with various alkynes under copper‐free conditions. The reusability of the catalyst was tested for up to four cycles without any significant loss in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
24.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling. 相似文献
25.
26.
27.
28.
Yuyang Ji Rebekka S. Klausen 《Journal of polymer science. Part A, Polymer chemistry》2021,59(21):2521-2529
The synthesis of vinyl alcohol copolymers is limited due to the poor radical reactivity of vinyl acetate (VAc), the traditional precursor to polyvinyl alcohol (PVA). Main group monomers such as BN 2-vinylnaphthalene (BN2VN) have attracted attention as alternatives to VAc to form side chain hydroxyls via oxidation, but outstanding questions of molecular weight control remain. Herein we report systematic investigation of solvent, temperature, and initiator concentration as factors influencing BN2VN degree of polymerization. We find increased chain transfer to toluene, hypothesized to arise from differences in radical stabilization and reactivity by aromatic and BN aromatic rings. As a result of these combined efforts, high molecular weight (Mw ~ 105 g mol−1) BN2VN homopolymers and BN2VN-styrene copolymers were obtained. 相似文献
29.
30.
Applied Magnetic Resonance - The suggested approach allowed us to derive analytical expressions for modeling the shape of solid-echo signal and its time evolution for a system of three-spin groups... 相似文献