全文获取类型
收费全文 | 6242篇 |
免费 | 1097篇 |
国内免费 | 794篇 |
专业分类
化学 | 4257篇 |
晶体学 | 42篇 |
力学 | 456篇 |
综合类 | 33篇 |
数学 | 762篇 |
物理学 | 2583篇 |
出版年
2024年 | 14篇 |
2023年 | 135篇 |
2022年 | 199篇 |
2021年 | 192篇 |
2020年 | 226篇 |
2019年 | 249篇 |
2018年 | 187篇 |
2017年 | 191篇 |
2016年 | 276篇 |
2015年 | 309篇 |
2014年 | 307篇 |
2013年 | 374篇 |
2012年 | 550篇 |
2011年 | 602篇 |
2010年 | 401篇 |
2009年 | 320篇 |
2008年 | 421篇 |
2007年 | 379篇 |
2006年 | 359篇 |
2005年 | 335篇 |
2004年 | 282篇 |
2003年 | 196篇 |
2002年 | 175篇 |
2001年 | 147篇 |
2000年 | 109篇 |
1999年 | 151篇 |
1998年 | 106篇 |
1997年 | 118篇 |
1996年 | 129篇 |
1995年 | 116篇 |
1994年 | 84篇 |
1993年 | 67篇 |
1992年 | 58篇 |
1991年 | 67篇 |
1990年 | 67篇 |
1989年 | 53篇 |
1988年 | 41篇 |
1987年 | 27篇 |
1986年 | 34篇 |
1985年 | 27篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 12篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1957年 | 3篇 |
排序方式: 共有8133条查询结果,搜索用时 0 毫秒
211.
212.
Pengcheng Li Jie Dai Yi Xu Qichao Ran Yi Gu 《Journal of polymer science. Part A, Polymer chemistry》2019,57(14):1587-1592
A difunctional benzoxazine (coPh‐apa) with a conjugated alkyne group is synthesized by the oxidative coupling reaction from a monocycle‐benzoxazine (Ph‐apa) containing an alkyne group. A model compound, 1,4‐diphenylbutadiyne (coPa), is used to study the curing reaction process of coPh‐apa by DSC, Fourier transform infrared spectroscopy, and 13C NMR, and the results suggest that the conjugated alkyne groups are involved in the crosslinking reaction via the trimerization reaction of the conjugated alkynyl groups and the Diels–Alder reaction. Furthermore, thermal properties of the polybenzoxazine are studied by dynamic thermomechanical analysis and thermogravimetric analysis. A glass‐transition temperature (Tgs) of as high as 412 °C and a char yield of 75.6% at 800 °C under nitrogen are obtained with the aid of the conjugated alkyne groups. Its excellent heat resistance dominates most thermosetting resins and will serve for heat shields. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1587–1592 相似文献
213.
Dongdong Li Luyao Wang Ernesto Yagüe Linlin Dai Xiumei Zhao Zibo Yang Shuang Zhi Yunhui Hu 《应用有机金属化学》2019,33(10)
An innovative ternary copper(II) complex, [Cu(Cl‐PIP)(Tyr)Cl]n, has been synthesized and characterized using infrared spectroscopy, elemental analysis and single‐crystal X‐ray diffraction analysis. X‐ray crystallography indicates that the Cu atom is five‐coordinated in a square‐pyramidal configuration. The unit forms a one‐dimensional chain along the crystallographic c‐axis. The complex was screened for cytotoxicity against a panel of eight human cancer cell lines, namely MDA‐MB‐231, CAL‐51, K562, HeLa, SGC‐7901, A549, MCF‐7 and SMMC‐7721. The best anticancer activity was obtained with triple‐negative breast cancer CAL‐51 and MDA‐MB‐231 cell lines, with IC50 values in the range 0.035–0.10 μM, and this was better than using carboplatin. The complex inhibits proteasomal chymotrypsin‐like activity, and docking studies reveal its interaction with 20S proteasome. In addition, the complex causes accumulation of ubiquitinated proteins, induces apoptosis and inhibits cell proliferation, indicating its great potential as a novel therapy for triple‐negative breast cancer. 相似文献
214.
215.
Besides dispersion engineering, idler-band distributed fiber loss provides a new synthesis freedom to flatten and broaden the gain spectrum for a fiber-optic parametric amplifier. This interesting phenomenon is based on the fact that the power balance between signal and idler is broken by idler loss, which changes the power conversion process in four-wave-mixing. The pump-to-signal conversion efficiency is kept unchanged in spite of the loss. 相似文献
216.
217.
Jun Dai Lin Li LiPing He KangCheng Ruan HuiBin Lu KuiJuan Jin GuoZhen Yang 《中国科学:物理学 力学 天文学(英文版)》2014,57(11):2039-2042
In this work, we parallelly detected the specific binding between microarray targets including 12 different kinds of proteins and the probe solution containing five corresponding antibodies and quantitatively analyzed the interactions between CDH13 and solution phase anti-CDH13 at six different probe concentrations by oblique-incidence reflectivity difference (OIRD) method in label-free format. The detection sensitivity reached 10 ng/mL. The experimental results indicate that the OIRD method is a promising and competing technique not only in research work but also in clinic. 相似文献
218.
219.
220.