全文获取类型
收费全文 | 45933篇 |
免费 | 18130篇 |
国内免费 | 74篇 |
专业分类
化学 | 57525篇 |
晶体学 | 97篇 |
力学 | 2068篇 |
数学 | 2740篇 |
物理学 | 1707篇 |
出版年
2024年 | 157篇 |
2023年 | 4079篇 |
2022年 | 1436篇 |
2021年 | 2500篇 |
2020年 | 4639篇 |
2019年 | 2349篇 |
2018年 | 2294篇 |
2017年 | 604篇 |
2016年 | 5591篇 |
2015年 | 5553篇 |
2014年 | 4977篇 |
2013年 | 5295篇 |
2012年 | 3307篇 |
2011年 | 1198篇 |
2010年 | 3499篇 |
2009年 | 3441篇 |
2008年 | 1219篇 |
2007年 | 902篇 |
2006年 | 284篇 |
2005年 | 242篇 |
2004年 | 197篇 |
2003年 | 181篇 |
2002年 | 197篇 |
1997年 | 122篇 |
1996年 | 130篇 |
1995年 | 192篇 |
1994年 | 120篇 |
1993年 | 242篇 |
1992年 | 137篇 |
1988年 | 139篇 |
1987年 | 129篇 |
1985年 | 176篇 |
1984年 | 166篇 |
1983年 | 131篇 |
1982年 | 170篇 |
1981年 | 182篇 |
1980年 | 236篇 |
1979年 | 228篇 |
1978年 | 231篇 |
1977年 | 339篇 |
1976年 | 392篇 |
1975年 | 483篇 |
1974年 | 489篇 |
1973年 | 303篇 |
1972年 | 380篇 |
1971年 | 369篇 |
1970年 | 545篇 |
1969年 | 419篇 |
1968年 | 460篇 |
1967年 | 118篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Fluorinated Musk Fragrances: The CF2 Group as a Conformational Bias Influencing the Odour of Civetone and (R)‐Muscone 下载免费PDF全文
Dr. Ricardo Callejo Dr. Michael J. Corr Mingyan Yang Prof. Mingan Wang Dr. David B. Cordes Prof. Alexandra M. Z. Slawin Prof. David O'Hagan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8137-8151
The difluoromethylene (CF2) group has a strong tendency to adopt corner over edge locations in aliphatic macrocycles. In this study, the CF2 group has been introduced into musk relevant macrocyclic ketones. Nine civetone and five muscone analogues have been prepared by synthesis for structure and odour comparisons. X‐ray studies indeed show that the CF2 groups influence ring structure and they give some insight into the preferred ring conformations, triggering a musk odour as determined in a professional perfumery environment. The historical conformational model of Bersuker and co‐workers for musk fragrance generally holds, and structures that become distorted from this consensus, by the particular placement of the CF2 groups, lose their musk fragrance and become less pleasant. 相似文献
992.
993.
Inside Back Cover: Synthesis and Isolation of the Titanium–Scandium Endohedral Fullerenes—Sc2TiC@Ih‐C80, Sc2TiC@D5h‐C80 and Sc2TiC2@Ih‐C80: Metal Size Tuning of the TiIV/TiIII Redox Potentials (Chem. Eur. J. 37/2016) 下载免费PDF全文
994.
Mixed Polymer‐Coated Magnetic Nanoparticles as Forward Osmosis Draw Agents of Tuned Hydrophilicity 下载免费PDF全文
Dr. Priyanka Dey Dr. Emad L. Izake 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(32):11253-11260
We recently reported a polymer‐coated magnetic nanoparticle (MNP) draw agent for the forward osmosis (FO) water desalination process. The water flux was found to increase when the polymer poly(sodium acrylate) (PSA) was anchored to the MNP surface as compared to the polymer (or polyelectrolyte solution) alone, due to the polymer chains being stretched out and most of the hydrophilic groups on the polymer contributing to water flux. We herein report the use of a secondary polymer poly(N‐isopropylacrylamide) PNIPAM to manipulate the PSA polymer conformation and influence inter‐ and intrachain interactions to enhance the efficiency of the FO draw agent. These PSA–PNIPAM‐coated MNPs generated a much higher water flux of ~11.66 LMH when compared to the 100 % PSA‐coated MNPs featuring a value of ~5.32 LMH under identical FO conditions. The osmotic pressure and water flux driven by the mixed polymer‐coated MNPs were found to be a strong function of the net polymer coverage on MNPs, that is, net available hydrophilic groups. Our new draw agent demonstrates potential for use in the water industry due to its improved efficiency and cost effectiveness as it uses only ~0.062 % (w/v) of the draw agent solution. 相似文献
995.
996.
997.
998.
999.