全文获取类型
收费全文 | 31607篇 |
免费 | 5383篇 |
国内免费 | 3615篇 |
专业分类
化学 | 22648篇 |
晶体学 | 363篇 |
力学 | 1777篇 |
综合类 | 207篇 |
数学 | 3857篇 |
物理学 | 11753篇 |
出版年
2024年 | 67篇 |
2023年 | 561篇 |
2022年 | 839篇 |
2021年 | 1058篇 |
2020年 | 1177篇 |
2019年 | 1199篇 |
2018年 | 1111篇 |
2017年 | 958篇 |
2016年 | 1520篇 |
2015年 | 1399篇 |
2014年 | 1778篇 |
2013年 | 2312篇 |
2012年 | 2805篇 |
2011年 | 3018篇 |
2010年 | 2071篇 |
2009年 | 2009篇 |
2008年 | 2254篇 |
2007年 | 1955篇 |
2006年 | 1808篇 |
2005年 | 1423篇 |
2004年 | 1108篇 |
2003年 | 855篇 |
2002年 | 971篇 |
2001年 | 773篇 |
2000年 | 649篇 |
1999年 | 676篇 |
1998年 | 484篇 |
1997年 | 472篇 |
1996年 | 498篇 |
1995年 | 423篇 |
1994年 | 320篇 |
1993年 | 324篇 |
1992年 | 228篇 |
1991年 | 250篇 |
1990年 | 198篇 |
1989年 | 164篇 |
1988年 | 129篇 |
1987年 | 112篇 |
1986年 | 105篇 |
1985年 | 82篇 |
1984年 | 76篇 |
1983年 | 52篇 |
1982年 | 46篇 |
1981年 | 34篇 |
1980年 | 31篇 |
1976年 | 17篇 |
1975年 | 16篇 |
1974年 | 15篇 |
1973年 | 15篇 |
1968年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
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
2.
3.
Nonlinear Dynamics - This paper proposes an optimal parameter design of control scheme for mechanical systems by adopting the Stackelberg game theory. The goal of the control is to drive the... 相似文献
4.
Science China Mathematics - Linear factor models are familiar tools used in many fields. Several pioneering literatures established foundational theoretical results of the quasi-maximum likelihood... 相似文献
5.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry 下载免费PDF全文
6.
Nanocomposite hydrogel consisting of Na‐montmorillonite with enhanced mechanical properties 下载免费PDF全文
Ting Li Shuangfei Xiang Piming Ma Huiyu Bai Weifu Dong Mingqing Chen 《Journal of Polymer Science.Polymer Physics》2015,53(14):1020-1026
A new kind of nanocomposite (NC) hydrogel with Na‐montmorillonite (MMT) is presented in this article. The NC hydrogels were synthesized by free radical copolymerization of acrylamide and (3‐acrylamidopropyl) trimethylammonium chloride (ATC) in the presence of MMT and N,N′‐methylene‐bis‐acrylamide used as chemical cross‐linker. Due to the cation‐exchange reaction between MMT and ATC (cationic monomer) during the synthesis of NC hydrogels, MMT platelets were considered chemical “plane” cross‐linkers, different from “point” cross‐linkers. With increasing amount of MMT, the crosslinking degree enhanced, causing a decrease of the swelling degree at equilibrium. Investigations of mechanical properties indicated that NC hydrogels exhibited enhanced strength and toughness, which resulted from chemical interaction between exfoliated MMT platelets and polymer chains in hydrogels. Dynamic shear measurements showed that both storage modulus and loss modulus increased with increasing MMT content. The idea described here provided a new route to prepare hydrogels with high mechanical properties by using alternative natural Na‐MMT. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1020–1026 相似文献
7.
8.
JPC – Journal of Planar Chromatography – Modern TLC - A new high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous estimation of... 相似文献
9.
We investigate terahertz radiation(T-rays) from a pentacene organic diode at room temperature. The quantum chemistry calculation for frequency-related Huang–Rhys factor of pentacene is also carried out. The results demonstrate that the T-rays can come from a bending vibration of pentacene skeleton after the energy of pentacene exciton transferring to the vibrational excited state via electron–phonon coupling. Frequency and natural bond orbital analytics of pentacene and its derivatives are performed in order to explain the result and develop new materials to get higher emission. This work provides a new way to produce T-rays with a simple device at room temperature. 相似文献
10.
Synthesis and Photophysical Properties of a Sc3N@C80‐Corrole Electron Donor–Acceptor Conjugate 下载免费PDF全文
Bin Liu Hongyun Fang Prof. Xiaofang Li Wenting Cai Lipiao Bao Marc Rudolf Fabian Plass Prof. Louzhen Fan Prof. Xing Lu Prof. Dirk M. Guldi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):746-752
Embedding endohdedral metallofullerenes (EMFs) into electron donor–acceptor systems is still a challenging task owing to their limited quantities and their still largely unexplored chemical properties. In this study, we have performed a 1,3‐dipolar cycloaddition reaction of a corrole‐based precursor with Sc3N@C80 to regioselectively form a [5,6]‐adduct ( 1 ). The successful attachment of the corrole moiety was confirmed by mass spectrometry. In the electronic ground state, absorption spectra suggest sizeable electronic communications between the electron acceptor and the electron donor. Moreover, the addition pattern occurring at a [5,6]‐bond junction is firmly proven by NMR spectroscopy and electrochemical investigations performed with 1 . In the electronically excited state, which is probed in photophysical assays with 1 , a fast electron‐transfer yields the radical ion pair state consisting of the one‐electron‐reduced Sc3N@C80 and of the one‐electron‐oxidized corrole upon its exclusive photoexcitation. As such, our results shed new light on the practical work utilizing EMFs as building blocks in photovoltaics. 相似文献