全文获取类型
收费全文 | 1683篇 |
免费 | 86篇 |
国内免费 | 5篇 |
专业分类
化学 | 1189篇 |
晶体学 | 2篇 |
力学 | 25篇 |
数学 | 387篇 |
物理学 | 171篇 |
出版年
2023年 | 13篇 |
2022年 | 10篇 |
2021年 | 29篇 |
2020年 | 31篇 |
2019年 | 46篇 |
2018年 | 24篇 |
2017年 | 17篇 |
2016年 | 56篇 |
2015年 | 56篇 |
2014年 | 53篇 |
2013年 | 57篇 |
2012年 | 113篇 |
2011年 | 143篇 |
2010年 | 68篇 |
2009年 | 55篇 |
2008年 | 81篇 |
2007年 | 82篇 |
2006年 | 104篇 |
2005年 | 94篇 |
2004年 | 60篇 |
2003年 | 62篇 |
2002年 | 45篇 |
2001年 | 27篇 |
2000年 | 21篇 |
1999年 | 19篇 |
1998年 | 29篇 |
1997年 | 27篇 |
1996年 | 33篇 |
1995年 | 29篇 |
1994年 | 30篇 |
1993年 | 24篇 |
1992年 | 36篇 |
1991年 | 31篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 13篇 |
1982年 | 6篇 |
1979年 | 7篇 |
1976年 | 8篇 |
1974年 | 5篇 |
1973年 | 4篇 |
1971年 | 4篇 |
1889年 | 3篇 |
1882年 | 5篇 |
1865年 | 3篇 |
排序方式: 共有1774条查询结果,搜索用时 15 毫秒
1.
2.
Cui Shisheng Shanbhag Uday Staudigl Mathias Vuong Phan 《Computational Optimization and Applications》2022,82(2):465-498
Computational Optimization and Applications - We develop a globalized Proximal Newton method for composite and possibly non-convex minimization problems in Hilbert spaces. Additionally, we impose... 相似文献
3.
Thomas Prenveille Cyrielle Garreau Mathias Matner Dirk Dijkstra Wilhelm Oppermann Diethelm Johannsmann 《Journal of polymer science. Part A, Polymer chemistry》2019,57(5):621-629
The reactivity of urethanes based on 1,6‐hexamethylene diisocyanate (HDI) and 4,4′‐methylene diphenyl diisocyanate (MDI) was investigated at temperatures between 190 °C and 235 °C. Diurethane model compounds end‐capped with either 1‐dodecanol (D‐core‐D) or 1‐hexadecanol (H‐core‐H) were mixed and annealed at high temperature. The core was either MDI or HDI. The transurethanization reaction was followed based on the formation of the compounds (H‐core‐D). The amount of H‐core‐D and of side products, which had formed after variable annealing times, were identified with 1H NMR, FTIR, SEC, and MALDI‐TOF. Transurethanization was considerably faster for MDI‐based urethanes than for HDI‐based urethanes. Only traces of side products were formed during annealing of MDI‐based urethanes, whereas a significant amount of allophanates was formed from HDI‐based urethanes under the same conditions. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 621–629 相似文献
4.
5.
6.
Towards Polysulfuric Acids: The Hydrogentrisulfate Anion [HS3O10]− in A[HS3O10] (A=Na,K, Rb) 下载免费PDF全文
Lisa Verena Schindler Prof. Dr. Thorsten Klüner Prof. Dr. Mathias S. Wickleder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):13865-13870
The reaction of Na2SO4 and K2SO4 with fuming sulfuric acid (65 % SO3) yielded colorless extremely sensitive crystals of Na[HS3O10] (monoclinic; P21/n (No. 14); Z=4; a=707.36(2), b=1378.56(4), c=848.10(3) pm; β=94.817(1)°; V=824.09(4) ? 106 pm3) and K[HS3O10] (orthorhombic; Pccn (No. 56); Z=4; a=1057.16(3), b=807.81(2), c=897.57(2) pm; V=766.51(3) ? 106 pm3). The analogous rubidium compound Rb[HS3O10] (orthorhombic; Pnma (No. 62); Z=4; a=891.43(3), b=1095.34(4), c=839.37(3) pm; V=819.58(5) ? 106 pm3) originates from the reaction of Rb2CO3 and SO3. All of the different structures contain the hitherto unknown anion [HS3O10]? and are stamped by strong hydrogen bonds linking the anions either to dimers or chains. Theoretical investigations by DFT methods give further insight in the structural characteristics of [HS3O10]?. The preparation of the [HS3O10]? anion can be seen as an important milestone on our way to the still elusive polysulfuric acids. 相似文献
7.
8.
9.
Prof. Dr. Carsten Jenne Dr. Mathias Keßler Jonas Warneke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5887-5891
The acidity of protic cations and neutral molecules has been studied extensively in the gas phase, and the gas‐phase acidity has been established previously as a very useful measure of the intrinsic acidity of neutral and cationic compounds. However, no data for any anionic acids were available prior to this study. The protic anions [H(B12X12)]? (X=F, Cl, Br, I) are expected to be the most acidic anions known to date. Therefore, they were investigated in this study with respect to their ability to protonate neutral molecules in the gas phase by using a combination of mass spectrometry and quantum‐chemical calculations. For the first time it was shown that in the gas phase protic anions are also able to protonate neutral molecules and thus act as Brønsted acids. According to theoretical calculations, [H(B12I12)]? is the most acidic gas‐phase anion, whereas in actual protonation experiments [H(B12Cl12)]? is the most potent gas‐phase acidic anion for the protonation of neutral molecules. This discrepancy is explained by ion pairing and kinetic effects. 相似文献
10.