全文获取类型
收费全文 | 22001篇 |
免费 | 3880篇 |
国内免费 | 3241篇 |
专业分类
化学 | 16626篇 |
晶体学 | 294篇 |
力学 | 1345篇 |
综合类 | 221篇 |
数学 | 2916篇 |
物理学 | 7720篇 |
出版年
2024年 | 43篇 |
2023年 | 323篇 |
2022年 | 466篇 |
2021年 | 669篇 |
2020年 | 781篇 |
2019年 | 847篇 |
2018年 | 732篇 |
2017年 | 683篇 |
2016年 | 1055篇 |
2015年 | 1139篇 |
2014年 | 1294篇 |
2013年 | 1624篇 |
2012年 | 1929篇 |
2011年 | 2085篇 |
2010年 | 1561篇 |
2009年 | 1535篇 |
2008年 | 1697篇 |
2007年 | 1432篇 |
2006年 | 1298篇 |
2005年 | 1078篇 |
2004年 | 887篇 |
2003年 | 764篇 |
2002年 | 910篇 |
2001年 | 753篇 |
2000年 | 575篇 |
1999年 | 485篇 |
1998年 | 379篇 |
1997年 | 302篇 |
1996年 | 320篇 |
1995年 | 276篇 |
1994年 | 189篇 |
1993年 | 171篇 |
1992年 | 141篇 |
1991年 | 140篇 |
1990年 | 99篇 |
1989年 | 92篇 |
1988年 | 58篇 |
1987年 | 53篇 |
1986年 | 44篇 |
1985年 | 33篇 |
1984年 | 31篇 |
1983年 | 32篇 |
1982年 | 18篇 |
1981年 | 22篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1974年 | 9篇 |
1971年 | 5篇 |
1957年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 937 毫秒
1.
Let p ∈ [1, ∞), q ∈ [1, ∞), α∈ R, and s be a non-negative integer. Inspired by the space JNp introduced by John and Nirenberg(1961) and the space B introduced by Bourgain et al.(2015), we introduce a special John-Nirenberg-Campanato space JNcon(p,q,s) over Rn or a given cube of R;with finite side length via congruent subcubes, which are of some amalgam features. The limit space of such spaces as p →∞ is just the Campanato space which coincides with the space BMO(the space of functions with bounded mean oscillations)when α = 0. Moreover, a vanishing subspace of this new space is introduced, and its equivalent characterization is established as well, which is a counterpart of the known characterization for the classical space VMO(the space of functions with vanishing mean oscillations) over Rn or a given cube of Rn with finite side length.Furthermore, some VMO-H1-BMO-type results for this new space are also obtained, which are based on the aforementioned vanishing subspaces and the Hardy-type space defined via congruent cubes in this article. The geometrical properties of both the Euclidean space via its dyadic system and congruent cubes play a key role in the proofs of all these results. 相似文献
2.
Zeng Qing-Wei Wen Zhuo-Yu Fu Jun-Feng Zhou Nan-Run 《International Journal of Theoretical Physics》2021,60(9):3306-3333
International Journal of Theoretical Physics - A new quantum watermark algorithm is presented by combining maximum pixel difference partitioning with the least significant bit substitution... 相似文献
3.
本文合成了配合物[Cu(pcba)2·(phen)(H2O)] (pcba =对氯苯甲酸,phen = 1,10-邻菲罗啉),该配合物属于三斜晶系,P1空间群,晶胞参数为a=0.790 98(2) nm,b=1.072 40(4) nm,c=1.487 19(6) nm,α=100.613(3)°,β=95.239(3)°,γ=108.334(3)°,Z=2,Dc=1.638 g·cm-3,F(000)=582,最终结构残差因子R1=0.035 9,wR2=0.089 1。采用紫外及荧光研究了配合物和人血清蛋白(HSA)的相互作用方式。结果表明,配合物静态猝灭HSA荧光,可求得配合物与HSA的猝灭常数Ksv=2.35×105 L·mol-1,猝灭速率常数Kq=2.35×1013 L·mol-1·s-1,结合常数为Ka=2.14×1013 L·mol-1,结合位点n=2.37。同时,研究了配合物对胃癌细胞A549、宫颈癌细胞Hela和肝癌细胞HepG2的抗增殖能力。 相似文献
4.
We experimentally analyze the heat capacity and thermal expansion of reference solids in a wide temperature range from several Kelvin to melting temperature,and establish a universal double-linear relation between the experimental heat capacity Cp and thermal expansion β,which is different from the previous models.The universal behavior between heat capacity and thermal expansion is important to predict the thermodynamic parameters at constant pressure,and is helpful for understanding the nature of thermal properties in solids. 相似文献
5.
6.
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
7.
8.
9.
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
10.