全文获取类型
收费全文 | 1318篇 |
免费 | 36篇 |
国内免费 | 5篇 |
专业分类
化学 | 1045篇 |
晶体学 | 13篇 |
力学 | 5篇 |
数学 | 53篇 |
物理学 | 243篇 |
出版年
2022年 | 12篇 |
2021年 | 14篇 |
2020年 | 26篇 |
2019年 | 23篇 |
2018年 | 17篇 |
2017年 | 8篇 |
2016年 | 24篇 |
2015年 | 25篇 |
2014年 | 25篇 |
2013年 | 84篇 |
2012年 | 57篇 |
2011年 | 66篇 |
2010年 | 29篇 |
2009年 | 43篇 |
2008年 | 67篇 |
2007年 | 63篇 |
2006年 | 67篇 |
2005年 | 67篇 |
2004年 | 77篇 |
2003年 | 76篇 |
2002年 | 52篇 |
2001年 | 54篇 |
2000年 | 36篇 |
1999年 | 20篇 |
1998年 | 6篇 |
1997年 | 18篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 20篇 |
1992年 | 15篇 |
1991年 | 6篇 |
1989年 | 14篇 |
1988年 | 19篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 16篇 |
1984年 | 23篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 10篇 |
1970年 | 8篇 |
排序方式: 共有1359条查询结果,搜索用时 15 毫秒
81.
5,11-Diazadibenzo[hi,qr]tetracene: Synthesis,Properties, and Reactivity toward Nucleophilic Reagents
Dr. Keisuke Fujimoto Satoshi Takimoto Shota Masuda Dr. Toshiyasu Inuzuka Kazutaka Sanada Prof. Dr. Masami Sakamoto Prof. Dr. Masaki Takahashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(35):8951-8955
5,11-Diazadibenzo[hi,qr]tetracene was synthesized as a new nitrogen-substituted polycyclic heteroaromatic compound by Pd-catalyzed cycloisomerization of an alkyne precursor followed by oxidative cyclization with bis(trifluoroacetoxy)iodobenzene. The substitution of imine-type nitrogen atoms significantly enhanced its electron-accepting character and facilitated the direct nucleophilic addition of arylamines under strongly basic conditions to afford the desired amino-substituted products. The introduction of amino groups induced a remarkable red-shift in their absorption spectra; the tetrasubstituted product exhibited intense near-infrared absorbing property. Furthermore, the π-electronic system, which includes a redox-active 1,4-diazabutadiene moiety, underwent reversible interconversion to its corresponding reduced form upon reduction with NaBH4 and aerobic oxidation. 相似文献
82.
83.
Shunichi Sakamoto Toshiyuki Sasaki Ayana Sato‐Tomita Satoshi Takamizawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(39):13860-13864
As altering permanent shapes without loss of material function is of practical importance for material molding, especially for elastic materials, shape‐rememorization ability would enhance the utility of elastic crystalline materials. Since diffusionless plastic deformability can preserve the crystallinity of materials, the interconversion of diffusionless mechanical deformability between superelasticity and ferroelasticity could enable shape rememorization of superelastic single crystals. This study demonstrates the shape rememorization of an organosuperelastic single crystal of 1,4‐dicyanobenzene through time‐reversible interconversion of superelasticity–ferroelasticity relaxation by holding the mechanically twinned crystal without heating. The shape‐rememorization ability of the organosuperelastic crystal indicates the compatibility of superelasticity (antiferroelasticity) and ferroelasticity as well as the intrinsic workability of organic crystalline materials capable of recovering their crystal functions under mild conditions. 相似文献
84.
85.
86.
(+)-Boronolide and (+)-deacetylboronolide were synthesized using Pd-catalyzed CO insertion and lactonization as the key step. As to the 13C NMR data of (+)-deacetylboronolide, the assignment at C-6 position should be revised. 相似文献
87.
Emiko Igarashi Kenta Sakamoto Tomoyuki Yoshimura Jun-ichi Matsuo 《Tetrahedron letters》2019,60(1):13-15
Various 3-phenylcyclobutanones reacted with aliphatic and aromatic nitriles in the presence of Me3SiOTf to afford dihydropyridones by formal [4+2] cycloaddition. 相似文献
88.
A co-cross-linking reaction of bio-based multi-functional epoxides (1) derived from limonene oxide and bisphenol A diglycidyl ether (BPADE) in the presence of 2-ethyl-4-methylimidazole (EMI) as a cross-linker afforded the corresponding network copolymers (2) having the 10% thermal decomposition temperature (Td10) of 294.4?°C at maximum. Adhesive strength induced by 1, especially tetra-functional epoxide, and BPADE exhibited remarkably higher than that by BPADE alone. 相似文献
89.
90.
Kyoungmin Kang Kosuke Sakamoto Dr. Yoshihiro Nishimoto Prof. Dr. Makoto Yasuda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(22):4930-4934
The regioselective anti-carboindation of ynamides by using InBr3 and silylated nucleophiles was developed to synthesize (Z)-β-(carbonylamino)alkenylindiums. The X-ray crystallographic analysis of an alkenylindium suggested that the reaction proceeded in an anti-addition fashion. In contrast to reported syn-carbometalations of ynamides by using organometallics, a cooperation of InBr3 and silylated nucleophiles to ynamides achieved an anti-addition, which was supported by DFT calculations. The scope of substrates included various ynamides and silylated nucleophiles, such as silyl ketene acetals and silyl ketene imines. The transformation of synthesized alkenylindiums by iodination, radical coupling, and Pd-catalyzed cross-coupling successfully afforded trisubstituted enamines with high regio- and stereoselectivities. 相似文献