全文获取类型
收费全文 | 328150篇 |
免费 | 6859篇 |
国内免费 | 2969篇 |
专业分类
化学 | 181460篇 |
晶体学 | 4669篇 |
力学 | 13839篇 |
综合类 | 137篇 |
数学 | 37840篇 |
物理学 | 100033篇 |
出版年
2021年 | 2211篇 |
2020年 | 2544篇 |
2019年 | 2582篇 |
2018年 | 2458篇 |
2017年 | 2354篇 |
2016年 | 4531篇 |
2015年 | 3922篇 |
2014年 | 5295篇 |
2013年 | 15151篇 |
2012年 | 12087篇 |
2011年 | 14851篇 |
2010年 | 9275篇 |
2009年 | 9226篇 |
2008年 | 13307篇 |
2007年 | 13514篇 |
2006年 | 12969篇 |
2005年 | 11801篇 |
2004年 | 10587篇 |
2003年 | 9260篇 |
2002年 | 9088篇 |
2001年 | 10426篇 |
2000年 | 8023篇 |
1999年 | 6358篇 |
1998年 | 5094篇 |
1997年 | 4887篇 |
1996年 | 4953篇 |
1995年 | 4506篇 |
1994年 | 4261篇 |
1993年 | 4054篇 |
1992年 | 4538篇 |
1991年 | 4380篇 |
1990年 | 4096篇 |
1989年 | 3901篇 |
1988年 | 4162篇 |
1987年 | 3821篇 |
1986年 | 3719篇 |
1985年 | 5356篇 |
1984年 | 5420篇 |
1983年 | 4393篇 |
1982年 | 4758篇 |
1981年 | 4800篇 |
1980年 | 4549篇 |
1979年 | 4673篇 |
1978年 | 4668篇 |
1977年 | 4645篇 |
1976年 | 4604篇 |
1975年 | 4513篇 |
1974年 | 4357篇 |
1973年 | 4527篇 |
1972年 | 2570篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Ben Jadi S. El Guerraf A. Bazzaoui E.A. Wang R. Martins J.I. Bazzaoui M. 《Journal of Solid State Electrochemistry》2019,23(8):2423-2433
Journal of Solid State Electrochemistry - Due to their distinctive chemical, electronic, and environmental properties, polypyrrole is used as a blocking barrier for methanol leakage in direct... 相似文献
72.
Kounta Moussa Dawson Nathan J. 《Methodology and Computing in Applied Probability》2021,23(3):1155-1172
Methodology and Computing in Applied Probability - The problem of optimally controlling one-dimensional diffusion processes until they enter a given stopping set is extended to include Markov... 相似文献
73.
74.
Ding Q. Yao M. Wu Sh. Zeng M. Xue N. Wu D. Xu J. 《Journal of Applied Spectroscopy》2022,89(4):712-718
Journal of Applied Spectroscopy - Based on partial least squares (PLS) analysis, the effects of different smoothing points and different preprocessing methods on the accuracy and precision of the... 相似文献
75.
Transport in Porous Media - The theme of coupling problems for adsorption, absorption and thermochemical transport in porous media is very important for engineering applications. Based on the... 相似文献
76.
77.
78.
79.
Monodisperse aqueous upconverting nanoparticles (UCNPs) were covalently immobilized on aldehyde modified cellulose paper via reduction amination to develop a luminescence resonance energy transfer (LRET)-based nucleic acid hybridization assay. This first account of covalent immobilization of UCNPs on paper for a bioassay reports an optically responsive method that is sensitive, reproducible and robust. The immobilized UCNPs were decorated with oligonucleotide probes to capture HPRT1 housekeeping gene fragments, which in turn brought reporter conjugated quantum dots (QDs) in close proximity to the UCNPs for LRET. This sandwich assay could detect unlabeled oligonucleotide target, and had a limit of detection of 13 fmol and a dynamic range spanning nearly 3 orders of magnitude. The use of QDs, which are excellent LRET acceptors, demonstrated improved sensitivity, limit of detection, dynamic range and selectivity compared to similar assays that have used molecular fluorophores as acceptors. The selectivity of the assay was attributed to the decoration of the QDs with polyethylene glycol to eliminate non-specific adsorption. The kinetics of hybridization were determined to be diffusion limited and full signal development occurred within 3 min. 相似文献
80.
An N. Le Ruiqi Liang Xiaoyu Ji Xiaowei Fu Mingjiang Zhong 《Journal of polymer science. Part A, Polymer chemistry》2021,59(21):2571-2580
The random copolymerization of norbornene-functionalized macromonomers was explored as a method of synthesizing mixed-graft block copolymers (mGBCPs). The copolymerization kinetics of a model system of polystyrene (PS) and poly(lactic acid) (PLA) macromonomers was first analyzed, revealing a gradient composition of side chains along the mGBCP backbone. The phase separation behavior of mGBCPs with PS and PLA side chains of various backbone lengths and side chain molar ratios was investigated, and increasing the backbone length was found to stabilize the phase-separated nanostructures. The graft architecture was also demonstrated to improve the processability of the mGBCP, compared to a linear counterpart. Investigations of mGBCPs comprised of polydimethylsiloxane and poly(ethylene oxide) side chains exemplified the diverse self-assembled morphologies, including a Frank-Kasper A15 phase, that can be obtained with mGBCPs synthesized by random copolymerization of macromonomers. Lastly, a ternary mGBCP was synthesized by the copolymerization of three macromonomers. 相似文献