全文获取类型
收费全文 | 2706篇 |
免费 | 112篇 |
国内免费 | 7篇 |
专业分类
化学 | 2125篇 |
晶体学 | 7篇 |
力学 | 41篇 |
数学 | 384篇 |
物理学 | 268篇 |
出版年
2024年 | 2篇 |
2023年 | 25篇 |
2022年 | 78篇 |
2021年 | 94篇 |
2020年 | 71篇 |
2019年 | 76篇 |
2018年 | 37篇 |
2017年 | 42篇 |
2016年 | 109篇 |
2015年 | 96篇 |
2014年 | 102篇 |
2013年 | 166篇 |
2012年 | 195篇 |
2011年 | 201篇 |
2010年 | 153篇 |
2009年 | 113篇 |
2008年 | 169篇 |
2007年 | 150篇 |
2006年 | 136篇 |
2005年 | 136篇 |
2004年 | 130篇 |
2003年 | 102篇 |
2002年 | 98篇 |
2001年 | 34篇 |
2000年 | 40篇 |
1999年 | 31篇 |
1998年 | 25篇 |
1997年 | 25篇 |
1996年 | 30篇 |
1995年 | 21篇 |
1994年 | 22篇 |
1993年 | 18篇 |
1992年 | 21篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有2825条查询结果,搜索用时 2 毫秒
71.
Monika Schuster Claudia Turecek Helga Lichtenegger Robert Liska 《Applied Surface Science》2007,254(4):1131-1134
Continuously increasing life expectancy results in a rising number of bone diseases and fractures. Replacements from natural sources are not only limited in their availability, they also have some serious disadvantages such as possible immunological reactions or transmission of diseases. New synthetic biodegradable materials based on photopolymers could be an alternative solution. In these investigations an acrylate-based monomer formulation has been developed, consisting of a biodegradable basis monomer which is derived from gelatin, different reactive diluents, an appropriate photoinitiator and filler materials. For the three-dimensional shaping process stereolithography is the method of choice because of its capability to produce cellular structures with high resolutions. 相似文献
72.
Claudia Loerbroks Dr. Roberto Rinaldi Prof. Dr. Walter Thiel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(48):16282-16294
The molecular understanding of the chemistry of 1,4‐β‐glucans is essential for designing new approaches to the conversion of cellulose into platform chemicals and biofuels. In this endeavor, much attention has been paid to the role of hydrogen bonding occurring in the cellulose structure. So far, however, there has been little discussion about the implications of the electronic nature of the 1,4‐β‐glycosidic bond and its chemical environment for the activation of 1,4‐β‐glucans toward acid‐catalyzed hydrolysis. This report sheds light on these central issues and addresses their influence on the acid hydrolysis of cellobiose and, by analogy, cellulose. The electronic structure of cellobiose was explored by DFT at the BB1 K/6‐31++G(d,p) level. Natural bond orbital (NBO) analysis was performed to grasp the key bonding concepts. Conformations, protonation sites, and hydrolysis mechanisms were examined. The results for cellobiose indicate that cellulose is protected against hydrolysis not only by its supramolecular structure, as currently accepted, but also by its electronic structure, in which the anomeric effect plays a key role. 相似文献
73.
74.
75.
76.
77.
78.
Lorenzo Milli Dr. Nicola Zanna Andrea Merlettini Matteo Di Giosia Dr. Matteo Calvaresi Prof. Maria Letizia Focarete Prof. Claudia Tomasini 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):12106-12112
We present herein the preparation of four different hydrogels based on the pseudopeptide gelator Fmoc‐l ‐Phe‐d ‐Oxd‐OH (Fmoc=fluorenylmethyloxycarbonyl), either by changing the gelator concentration or adding graphene oxide (GO) to the water solution. The hydrogels have been analysed by rheological studies that demonstrated that pure hydrogels are slightly stronger compared to GO‐loaded hydrogels. Then the hydrogels efficiency to trap the cationic methylene blue (MB) and anionic eosin Y (EY) dyes has been analyzed. MB is efficiently trapped by both the pure hydrogel and the GO‐loaded hydrogel through π–π interactions and electrostatic interactions. In contrast, the removal of the anionic EY is achieved in less satisfactory yields, due to the unfavourable electrostatic interactions between the dye, the gelator and GO. 相似文献
79.
80.
Corrigendum: Triazole‐Tailored Guanosine Dinucleosides as Biomimetic Ion Channels to Modulate Transmembrane Potential 下载免费PDF全文