全文获取类型
收费全文 | 6570篇 |
免费 | 1119篇 |
国内免费 | 1473篇 |
专业分类
化学 | 5265篇 |
晶体学 | 97篇 |
力学 | 371篇 |
综合类 | 124篇 |
数学 | 904篇 |
物理学 | 2401篇 |
出版年
2024年 | 13篇 |
2023年 | 93篇 |
2022年 | 178篇 |
2021年 | 180篇 |
2020年 | 226篇 |
2019年 | 211篇 |
2018年 | 171篇 |
2017年 | 239篇 |
2016年 | 273篇 |
2015年 | 308篇 |
2014年 | 389篇 |
2013年 | 518篇 |
2012年 | 540篇 |
2011年 | 558篇 |
2010年 | 510篇 |
2009年 | 540篇 |
2008年 | 523篇 |
2007年 | 503篇 |
2006年 | 450篇 |
2005年 | 434篇 |
2004年 | 362篇 |
2003年 | 354篇 |
2002年 | 321篇 |
2001年 | 267篇 |
2000年 | 218篇 |
1999年 | 151篇 |
1998年 | 88篇 |
1997年 | 75篇 |
1996年 | 95篇 |
1995年 | 49篇 |
1994年 | 52篇 |
1993年 | 49篇 |
1992年 | 46篇 |
1991年 | 39篇 |
1990年 | 36篇 |
1989年 | 26篇 |
1988年 | 17篇 |
1987年 | 17篇 |
1986年 | 17篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有9162条查询结果,搜索用时 15 毫秒
61.
62.
Wei‐Lie Xiao Jian‐Xin Pu Rui‐Rui Wang Liu‐Meng Yang Xiao‐Li Li Sheng‐Hong Li Rong‐Tao Li Sheng‐Xiong Huang Yong‐Tang Zheng Han‐Dong Sun 《Helvetica chimica acta》2007,90(8):1505-1513
Seven new highly oxygenated nortriterpenoids, rubriflorins D–J ( 1 – 7 ), were isolated from the leaves and stems of Schisandra rubriflora, and their structures were elucidated on the basis of extensive analysis of spectroscopic data. These new compounds feature the opening of ring A compared with related known nortriterpenoids isolated from the genus Schisandra and showed weak activity against HIV‐1. 相似文献
63.
Amphiphilic biodegradable block copolymers [poly(sebacic anhydride)–poly(ethylene glycol)–poly(sebacic anhydride)] were synthesized by the melt polycondensation of poly(ethylene glycol) and sebacic anhydride prepolymers. The chemical structure, crystalline nature, and phase behavior of the resulting copolymers were characterized with 1H NMR, Fourier transform infrared, gel permeation chromatography, and differential scanning calorimetry. Microphase separation of the copolymers occurred, and the crystallinity of the poly(sebacic anhydride) (PSA) blocks diminished when the sebacic anhydride unit content in the copolymer was only 21.6%. 1H NMR spectra carried out in CDCl3 and D2O were used to demonstrate the existence of hydrophobic PSA domains as the core of the micelle. In aqueous media, the copolymers formed micelles after precipitation from water‐miscible solvents. The effects on the micelle sizes due to the micelle preparation conditions, such as the organic phase, dropping rate of the polymer organic solution into the aqueous phase, and copolymer concentrations in the organic phase, were studied. There was an increase in the micelle size as the molecular weight of the PSA block was increased. The diameters of the copolymer micelles were also found to increase as the concentration of the copolymer dissolved in the organic phase was increased, and the dependence of the micelle diameters on the concentration of the copolymer varied with the copolymer composition. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1271–1278, 2006 相似文献
64.
65.
66.
Degradation of 4-chlorophenol in aqueous solution by γ-radiation and ozone oxidation 总被引:5,自引:2,他引:3
HU Jun WANG Jianlong & CHEN Rong . Laboratory of Environmental Technology Institute of Nuclear Energy Technology Tsinghua University Beijing China . State Key Joint Laboratory of Environmental Simulation Pollution Control Tsinghua University Beijing China Correspondence should be addressed to Wang Jianlong 《中国科学B辑(英文版)》2006,(2)
The application of radiation technology in the en-vironmental protection was listed as one of the mostimportant research fields by the International AtomicEnergy Agency (IAEA) for the peaceful use of nuclearenergy. It has great research value and potential appli-cation. Because of their broad-spectrum antimicrobialproperties, Cholophenols (CPs) have been used aspreservative agents for wood, paints, vegetable fibersand leather and as disinfectants. In addition, they havebeen widely employed… 相似文献
67.
68.
分别采用功率密度为1.7W/cm2、照射剂量为2000J/cm2的Ar+激光与LD激光辐照高耐药性的志贺氏福氏痢疾杆菌,波长较短的Ar+激光(488nm)所引起细菌的致死率与药敏实变率明显高于波长较长的LD激光(808nm),即波长较短的Ar+激光的辐照导致细菌耐药性显著降低. 相似文献
69.
70.
Ionic liquids are a new kind of room-temperature molten organic salts. It can be used as solvents in the organic/polymeric syntheses, and some of them are called "green" solvents because of its recyclability1. Ionic liquids possess the superior properties, such as thermal stability up to 200(C, involatility and re-designability(for both cation and anion). The ionic liquid employed in this work is [bmim] [PF6]- ( butylmethylimidazolium hexafluorophosphate ) which is immiscible with water and h… 相似文献