全文获取类型
收费全文 | 13237篇 |
免费 | 1663篇 |
国内免费 | 2867篇 |
专业分类
化学 | 4208篇 |
晶体学 | 244篇 |
力学 | 371篇 |
综合类 | 298篇 |
数学 | 682篇 |
物理学 | 2785篇 |
综合类 | 9179篇 |
出版年
2024年 | 33篇 |
2023年 | 111篇 |
2022年 | 289篇 |
2021年 | 286篇 |
2020年 | 271篇 |
2019年 | 250篇 |
2018年 | 249篇 |
2017年 | 382篇 |
2016年 | 335篇 |
2015年 | 526篇 |
2014年 | 669篇 |
2013年 | 825篇 |
2012年 | 932篇 |
2011年 | 944篇 |
2010年 | 1026篇 |
2009年 | 1098篇 |
2008年 | 1281篇 |
2007年 | 1178篇 |
2006年 | 1163篇 |
2005年 | 1076篇 |
2004年 | 777篇 |
2003年 | 589篇 |
2002年 | 620篇 |
2001年 | 642篇 |
2000年 | 646篇 |
1999年 | 298篇 |
1998年 | 128篇 |
1997年 | 103篇 |
1996年 | 88篇 |
1995年 | 83篇 |
1994年 | 102篇 |
1993年 | 111篇 |
1992年 | 89篇 |
1991年 | 80篇 |
1990年 | 75篇 |
1989年 | 70篇 |
1988年 | 60篇 |
1987年 | 51篇 |
1986年 | 54篇 |
1985年 | 37篇 |
1984年 | 36篇 |
1983年 | 21篇 |
1982年 | 19篇 |
1981年 | 15篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1971年 | 3篇 |
1965年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A thin film of manganese hexacyanoferrate (MnHCF) was electrochemically formed on a glassy carbon (GC) electrode to prepare a chemically modified electrode (CME). The mechanism of film formation of MnHCF and its growth process were investigated in detail by cyclic voltammetry. The results show that the stoichiometric composition of MnHCF is Mn^ⅢFe^Ⅲ(CN)6, an analogue of prussian yellow. There exist three clear-cut stages in the whole modification process and the last stage is indispensable to the fabrication of homogenized, stable MnHCF film and must last for an appropriate time. The surface morphology of MnHCF/GC electrode was characterized by scanning electron microscopy (SEM), which further verified the effective deposition of MnHCF film on GC. The kinetic constants of MnHCF/GC electrode process were also evaluated. The resulting MnHCF film modified electrode presented good stability and high electrocatalytic activity toward the oxidation of H2O2, indicating that MnHCF film possesses function of catalase and can be expected for analytical purposes. 相似文献
72.
73.
The dielectric loss factor and permittivity of a series of 1, 2-polybutadienes with different contents of 1, 2-units and different contents of syndiotactie 1, 2-units were determined over a frequency range from 30Hz to 100KHz at different temperatures. The WLF equation was evaluated for various samples with T_θat 100KHz as a reference temperature and the master curves of various samples have been constructed, which are in accordance with those calculated by Havriliak-Negami equation. The frequency dependence of the dielectric relaxation of 1, 2-polybutadienes was investigated over a frequency range from 10~0 Hz to 10~(12) ZHz in terms of the experimental data and the master curves. 相似文献
74.
75.
76.
用上升液滴法测定了2-乙基己基膦酸单(2-乙基己基)酯-正辛烷从硝酸介质中萃取镁、钙、锌、镍、铜和铅等二价金属离子的正向初始速率,建立了速率方程,计算出正向萃取反应的速率常数、活化能及活化熵,首次将软硬酸碱规则与金属溶萃取速率常数关联。结果表明,在萃取机理相同时,萃取速率常数的大小与金属离子的软硬酸碱标度一致,即萃取过程中,作为酸的被萃取金属离子,其硬度越大,萃取速率常数亦越大,萃取反应的活化能… 相似文献
77.
Ping ZHENG Wei Lin SUN Zhi Quan SHEN 《中国化学快报》2005,16(10):1413-1416
N-2-Thiazolylacrylamide (NTA) was polymerized by a radical route to obtain the polymer in good yield. The polymer with a pendent heterocyclic group is soluble in common organic solvents, which allow to prepare the corresponding metal complexes with higher loads easily. FTIR, ^1H NMR, elemental analysis, and energy-dispersive X-Ray spectroscopy (EDX) were applied to characterize these materials. The magnetic behavior of Fe(Ⅱ) and Nd(Ⅲ) complexes of poly(N-2-thiazolylacrylamide) was examined by a PPMS-9T magnetometer, exhibiting the characteristics of a soft ferromagnet. It is found that the Nd(Ⅲ) complex has an extremely high relative saturation magnetization of 35 emu/g. 相似文献
78.
A Novel Dimeric Coumarin from Clausena lenis 总被引:1,自引:0,他引:1
HongPingHE ShunTingCHEN YueMaoSHEN ChangXiangCHEN YiBinZHAO XiaoJiangHAO 《中国化学快报》2003,14(11):1150-1153
A novel dimeric coumarin (1), a dimeric of seselin named diseselin A, was isolated from the aerial part of Clausena lenis. The structure was elucidated based on the MS, 1D and 2D NMR data. 相似文献
79.
80.