全文获取类型
收费全文 | 3912篇 |
免费 | 674篇 |
国内免费 | 524篇 |
专业分类
化学 | 2604篇 |
晶体学 | 66篇 |
力学 | 261篇 |
综合类 | 23篇 |
数学 | 583篇 |
物理学 | 1573篇 |
出版年
2024年 | 13篇 |
2023年 | 91篇 |
2022年 | 138篇 |
2021年 | 168篇 |
2020年 | 184篇 |
2019年 | 149篇 |
2018年 | 169篇 |
2017年 | 181篇 |
2016年 | 181篇 |
2015年 | 185篇 |
2014年 | 225篇 |
2013年 | 295篇 |
2012年 | 340篇 |
2011年 | 357篇 |
2010年 | 226篇 |
2009年 | 261篇 |
2008年 | 265篇 |
2007年 | 221篇 |
2006年 | 256篇 |
2005年 | 184篇 |
2004年 | 119篇 |
2003年 | 106篇 |
2002年 | 104篇 |
2001年 | 86篇 |
2000年 | 71篇 |
1999年 | 76篇 |
1998年 | 68篇 |
1997年 | 52篇 |
1996年 | 61篇 |
1995年 | 38篇 |
1994年 | 40篇 |
1993年 | 31篇 |
1992年 | 26篇 |
1991年 | 32篇 |
1990年 | 26篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 13篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1957年 | 2篇 |
1929年 | 2篇 |
1926年 | 2篇 |
排序方式: 共有5110条查询结果,搜索用时 0 毫秒
71.
72.
73.
74.
Yi Yuan Zong-Lin Jiang Jia-Ming Yan Ge Gao Albert S. C. Chan Ru-Gang Xie 《合成通讯》2013,43(24):4555-4561
Two new macrobicyclic imidazolium and benzimidazolium phanes were synthesized by direct quaternization of the corresponding tripodal azacycles with tribromide under high dilution condition in excellent yields. The cyclophanes were identified by 1H-NMR, 13C-NMR, FAB-MS, IR, elemental analysis and X-ray diffraction analysis. 相似文献
75.
76.
Chen He Ban‐Kun Jin Wei‐Dong He Xue‐Song Ge Jing Tao Jing Yang Sheng‐Qi Chen 《Journal of polymer science. Part A, Polymer chemistry》2013,51(10):2142-2149
Long‐subchain hyperbranched polystyrene (lsc‐hp PSt) with uniform subchain length was obtained through copper‐catalyzed azide‐alkyne cycloaddition click chemistry from seesaw macromonomer of PSt having one alkynyl group anchored at the chain centre and two azido group attached to both chain ends [alkynyl‐(PSt‐N3)2]. After precipitation fraction, different portions of lsc‐hp PSt having narrow overall molecular weight distribution were obtained for further grafting with alkynyl‐capped poly(N‐isopropylacrylamide) (alkynyl‐PNIPAM), which was obtained via single‐electron transfer living radical polymerization of NIPAM with propargyl 2‐bromoisobutyrate as the initiator and grafted onto the peripheral azido groups of lsc‐hp PSt via click chemistry. Thus, amphiphilic lsc‐hp PSt grafted with PNIPAM chains (lsc‐hp PSt‐g‐PNIPAM) was obtained and would have star‐like conformation in tetrahydrofuran (THF). By replacing THF with water, lsc‐hp PSt‐g‐PNIPAM was dissolved at molecular level in aqueous solution due to the hydrophilicity of PNIPAM and exhibited thermal induced shrinkage of PNIPAM arms. The water‐insoluble lsc‐hp PSt would collapse densely and could be served as a reservoir to absorb hydrophobic chemicals in aqueous solution. The influence of overall molecular weight of lsc‐hp PSt on the absorption of pyrene was studied. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
77.
A novel configuration of fiber ring laser acoustic sensor, which adopts single-mode fiber as sensing element, is proposed and demonstrated. Linewidth less than 1 kHz is achieved by introducing a segment of erbium-doped fiber in the reflecting arm as saturable absorber. A polarization independent unbalanced Michelson interrogation interferometer and phase generated carrier demodulation technique are adopted to recover signal. Experiments demonstrate that the phase sensitivity is 0.018 rad/nm in good linearity and equivalent minimum detect able length change reaches 19.1 pm. 相似文献
78.
Frontispiece: Irreversible Denaturation of Proteins through Aluminum‐Induced Formation of Backbone Ring Structures 下载免费PDF全文
79.
Nan Jiang Xiao-Yu Yang Guo-Liang Ying Ling Shen Jing Liu Wei Geng Ling-Jun Dai Shao-Yin Liu Jian Cao Ge Tian Tao-Lei Sun Shi-Pu Li Bao-Lian Su 《Chemical science》2015,6(1):486-491
Self-repair is nature''s way of protecting living organisms. However, most single cells are inherently less capable of self-repairing, which greatly limits their wide applications. Here, we present a self-assembly approach to create a nanoshell around the cell surface using nanoporous biohybrid aggregates. The biohybrid shells present self-repairing behaviour, resulting in high activity and extended viability of the encapsulated cells (eukaryotic and prokaryotic cells) in harsh micro-environments, such as under UV radiation, natural toxin invasion, high-light radiation and abrupt pH-value changes. Furthermore, an interaction mechanism is proposed and studied, which is successful to guide design and synthesis of self-repairing biohybrid shells using different bioactive molecules. 相似文献
80.