全文获取类型
收费全文 | 2592篇 |
免费 | 281篇 |
国内免费 | 189篇 |
专业分类
化学 | 1961篇 |
晶体学 | 25篇 |
力学 | 14篇 |
综合类 | 5篇 |
数学 | 19篇 |
物理学 | 1038篇 |
出版年
2023年 | 27篇 |
2022年 | 60篇 |
2021年 | 100篇 |
2020年 | 110篇 |
2019年 | 78篇 |
2018年 | 65篇 |
2017年 | 67篇 |
2016年 | 110篇 |
2015年 | 109篇 |
2014年 | 86篇 |
2013年 | 193篇 |
2012年 | 92篇 |
2011年 | 96篇 |
2010年 | 73篇 |
2009年 | 132篇 |
2008年 | 116篇 |
2007年 | 181篇 |
2006年 | 162篇 |
2005年 | 91篇 |
2004年 | 85篇 |
2003年 | 109篇 |
2002年 | 106篇 |
2001年 | 91篇 |
2000年 | 51篇 |
1999年 | 75篇 |
1998年 | 69篇 |
1997年 | 53篇 |
1996年 | 36篇 |
1995年 | 31篇 |
1994年 | 30篇 |
1993年 | 20篇 |
1992年 | 31篇 |
1991年 | 20篇 |
1990年 | 23篇 |
1989年 | 25篇 |
1988年 | 23篇 |
1987年 | 12篇 |
1986年 | 27篇 |
1985年 | 17篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 18篇 |
1979年 | 17篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 18篇 |
1975年 | 9篇 |
1973年 | 13篇 |
排序方式: 共有3062条查询结果,搜索用时 31 毫秒
81.
Kyoichi Hanada Juntaro Nogami Prof. Dr. Kazunori Miyamoto Norihiko Hayase Dr. Yuki Nagashima Yusuke Tanaka Dr. Atsuya Muranaka Prof. Dr. Masanobu Uchiyama Prof. Dr. Ken Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9313-9319
The enantioselective synthesis of aza[6] and [7]helicene-like molecules have been achieved by the cationic rhodium(I)/axially chiral biaryl bisphosphine complex-catalyzed intramolecular [2+2+2] cycloaddition of cyanodiynes. This protocol was successfully applied to the diastereo- and enantioselective synthesis of an S-shaped double aza[6]helicene-like molecule with a high ee value of 89 %. Although no epimerization and racemization were observed in the double carbo[6]helicene-like molecule at 80 °C, epimerization and racemization of the double aza[6]helicene-like molecule proceeded at 80 °C. This double aza[6]helicene-like molecule showed good fluorescent quantum yields and chiroptical responses under both neutral and acidic conditions. 相似文献
82.
83.
84.
Pavel M. Polestshuk 《Journal of computational chemistry》2013,34(3):206-219
The approach for the integration over a region covered by zero‐flux surface is described. This approach based on the surface triangulation technique is efficiently realized in a newly developed program TWOE . The elaborated method is tested on several atomic properties including the source function. TWOE results are compared with those produced by using well‐known existing programs. Absolute errors in computed atomic properties are shown to range usually from 10?6 to 10?5 au. The demonstrative examples prove that present realization has perfect convergence of atomic properties with increasing size of angular grid and allows to obtain highly accurate data even in the most difficult cases. It is believed that the developed program can be bridgehead that allows to implement atomic partitioning of any desired molecular property with high accuracy. © 2012 Wiley Periodicals, Inc. 相似文献
85.
GEORGE JOHN HIROYUKI MINAMIKAWA MITSUTOSHI MASUDA TOSHIMI SHIMIZU 《Liquid crystals》2013,40(6):747-749
Two novel aryl glycosides were synthesized, which varied in the extent of unsaturation in the lipophilic part, from plant/crop-based renewable resource materials. Their liquid crystalline properties were characterized by optical polarizing microscopy, differential scanning calorimetry and X-ray diffraction. All the mesophases are identified as lamellar in structure. 相似文献
86.
Shuyang Liu Miao Tian Dr. Xiubin Bu Dr. Hua Tian Prof. Xiaobo Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(28):7738-7744
Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle. 相似文献
87.
Dr. Carel Kwamen Dr. Jochen Niemeyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):175-186
Mechanically interlocked molecules (MIMs) have gained attention in the field of catalysis due to their unique molecular properties. Central to MIMs, rotaxanes are highly promising and attractive supramolecular catalysts due to their unique three-dimensional structures and the flexibility of their subcomponents. This Minireview discusses the use of rotaxanes in organocatalysis and transition-metal catalysis. 相似文献
88.
With an attempt to fabricate large-area OLED lighting panels, we investigate slot-die coating of a small molecule (SM) hole transport layer (HTL). It is observed that SM HTL films formed by spin coating exhibit pinhole-like surface, whereas the films by slot-die coating show micro-sized hillocks due to agglomeration. As the plate temperature of the slot coater is increased, smaller hillocks appear more densely. To tackle it, a small amount of a polymer HTL is added into the SM HTL (Hybrid HTL). By the aid of entangled polymer chains, small molecules are prohibited from migrating and thus agglomerations disappear. The peak-to-peak roughness of the slot-coated hybrid HTL films is measured to be about 11.5 nm, which is slightly higher than that (~7 nm) of the polymer HTL film, but much lower than that (~1071 nm) of the SM HTL film. Similar results are also observed in spin-coated films. It is also addressed that OLED with the hybrid HTL shows higher luminous efficacy, compared to OLED with the SM HTL or the polymer HTL. We have further demonstrated that the dissolution problem occurring between two stacked layers with different solvents during slot-die coating can be suppressed to a great extent using such a combination of materials in hybrid structure. 相似文献
89.
Prof. James S. M. Anderson Prof. Juan I. Rodríguez Prof. Paul W. Ayers Daniel E. Trujillo-González Dr. Andreas W. Götz Prof. Jochen Autschbach Prof. Fray L. Castillo-Alvarado Prof. Koichi Yamashita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(10):2538-2544
The topology of the molecular electron density of benzene dithiol gold cluster complex Au4−S−C6H4−S′−Au′4 changed when relativistic corrections were made and the structure was close to a minimum of the Born–Oppenheimer energy surface. Specifically, new bond paths between hydrogen atoms on the benzene ring and gold atoms appeared, indicating that there is a favorable interaction between these atoms at the relativistic level. This is consistent with the observation that gold becomes a better electron acceptor when relativistic corrections are applied. In addition to relativistic effects, here, we establish the sensitivity of molecular topology to basis sets and convergence thresholds for geometry optimization. 相似文献