全文获取类型
收费全文 | 6480篇 |
免费 | 977篇 |
国内免费 | 541篇 |
专业分类
化学 | 4574篇 |
晶体学 | 31篇 |
力学 | 353篇 |
综合类 | 16篇 |
数学 | 786篇 |
物理学 | 2238篇 |
出版年
2023年 | 146篇 |
2022年 | 107篇 |
2021年 | 225篇 |
2020年 | 279篇 |
2019年 | 233篇 |
2018年 | 211篇 |
2017年 | 172篇 |
2016年 | 279篇 |
2015年 | 264篇 |
2014年 | 355篇 |
2013年 | 438篇 |
2012年 | 593篇 |
2011年 | 618篇 |
2010年 | 413篇 |
2009年 | 349篇 |
2008年 | 423篇 |
2007年 | 373篇 |
2006年 | 348篇 |
2005年 | 265篇 |
2004年 | 201篇 |
2003年 | 157篇 |
2002年 | 119篇 |
2001年 | 125篇 |
2000年 | 113篇 |
1999年 | 125篇 |
1998年 | 98篇 |
1997年 | 87篇 |
1996年 | 117篇 |
1995年 | 101篇 |
1994年 | 70篇 |
1993年 | 62篇 |
1992年 | 67篇 |
1991年 | 56篇 |
1990年 | 74篇 |
1989年 | 53篇 |
1988年 | 34篇 |
1987年 | 29篇 |
1986年 | 24篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 20篇 |
1978年 | 15篇 |
1977年 | 14篇 |
1976年 | 10篇 |
1975年 | 13篇 |
1973年 | 13篇 |
排序方式: 共有7998条查询结果,搜索用时 46 毫秒
21.
22.
23.
24.
Changyong Sun Guangzong Fang Xiaoguang Guo Yuanli Hu Shuqi Ma Tianhua Yang Jie Han Hao Ma Dali Tan Xinhe Bao 《天然气化学杂志》2015,(3):257-263
Long-term stability test of Mo/HZSM-5-N catalysts(HZSM-5-N stands for nano-sized HZSM-5) in methane dehydroaromatization(MDA)reaction has been performed with periodic CH4-H2 switch at 1033-1073 K for more than 1000 h.During this test,methane conversion ranges from 13% to 16%,and mean yield to aromatics(i.e.benzene and naphthalene) exceeds 10%.N2-physisorption,XRD,NMR and TPO measurements were performed for the used Mo/HZSM-5 catalysts and coke deposition,and the results revealed that the periodic hydrogenation can effectively suppress coke deposition by removing the inert aromatic-type coke,thus ensuring Mo/HZSM-5 partly maintained its activity even in the presence of large amount of coke deposition.The effect of zeolite particle size on the catalytic activity was also explored,and the results showed that the nano-sized zeolite with low diffusion resistance performed better.It is recognized that the size effect was enhanced by reaction time,and it became more remarkable in a long-term MDA reaction even at a low space velocity. 相似文献
25.
Mono‐ and Dinuclear Phosphorescent Rhenium(I) Complexes: Impact of Subcellular Localization on Anticancer Mechanisms 下载免费PDF全文
Rui‐Rong Ye Dr. Cai‐Ping Tan Mu‐He Chen Liang Hao Prof. Liang‐Nian Ji Prof. Zong‐Wan Mao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7800-7809
Elucidation of relationship among chemical structure, cellular uptake, localization, and biological activity of anticancer metal complexes is important for the understanding of their mechanisms of action. Organometallic rhenium(I) tricarbonyl compounds have emerged as potential multifunctional anticancer drug candidates that can integrate therapeutic and imaging capabilities in a single molecule. Herein, two mononuclear phosphorescent rhenium(I) complexes ( Re1 and Re2 ), along with their corresponding dinuclear complexes ( Re3 and Re4 ), were designed and synthesized as potent anticancer agents. The subcellular accumulation of Re1–Re4 was conveniently analyzed by confocal microscopy in situ in live cells by utilizing their intrinsic phosphorescence. We found that increased lipophilicity of the bidentate ligands could enhance their cellular uptake, leading to improved anticancer efficacy. The dinuclear complexes were more potent than the mononuclear counterparts. The molecular anticancer mechanisms of action evoked by Re3 and Re4 were explored in detail. Re3 with a lower lipophilicity localizes to lysosomes and induces caspase‐independent apoptosis, whereas Re4 with higher lipophilicity specially accumulates in mitochondria and induces caspase‐independent paraptosis in cancer cells. Our study demonstrates that subcellular localization is crucial for the anticancer mechanisms of these phosphorescent rhenium(I) complexes. 相似文献
26.
27.
Dang Huyen Vu Xuan Dang Hanh Vu Bich Doan Huu Dung Nguyen Tan Phong 《Research on Chemical Intermediates》2022,48(3):1311-1311
Research on Chemical Intermediates - 相似文献
28.
Tan Wei Ren Yuanlin Guo Yingbin Liu Yansong Liu Xiaohui Qu Hongqiang 《Cellulose (London, England)》2022,29(12):6941-6962
Cellulose - A novel DOPO derived multi-claw reactive flame retardant (DMCFR) was designed to improve the flame retardancy of lyocell fabric. The chemical structure of DMCFR was identified by proton... 相似文献
29.
Tian Xiu-Zhi Yang Rui Ma Jia-Jia Ni Yong-Hao Deng Hai-Bo Dai Lei Tan Jiao-Jun Zhang Mei-Yun Jiang Xue 《高分子科学》2022,40(7):789-798
Chinese Journal of Polymer Science - Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments. Herein, polyurethane was... 相似文献
30.
Ye‐Hui Chen Heng‐Hui Li Xiao Zhang Shao‐Hua Xiang Shaoyu Li Bin Tan 《Angewandte Chemie (International ed. in English)》2020,59(28):11374-11378
Presented here is a class of novel axially chiral aryl‐p‐quinones as platform molecules for the preparation of non‐C2 symmetric biaryldiols. Two sets of aryl‐p‐quinone frameworks were synthesized with remarkable enantiocontrol by means of chiral phosphoric acid catalyzed enantioselective arylation of p‐quinones by central‐to‐axial chirality conversion. These aryl‐p‐quinones were then used to access a wide spectrum of highly functionalized non‐C2 symmetric biaryldiols with excellent retention of the enantiopurity. 相似文献