全文获取类型
收费全文 | 22058篇 |
免费 | 2359篇 |
国内免费 | 2271篇 |
专业分类
化学 | 15203篇 |
晶体学 | 294篇 |
力学 | 1129篇 |
综合类 | 139篇 |
数学 | 2146篇 |
物理学 | 7777篇 |
出版年
2025年 | 14篇 |
2024年 | 233篇 |
2023年 | 427篇 |
2022年 | 717篇 |
2021年 | 838篇 |
2020年 | 975篇 |
2019年 | 976篇 |
2018年 | 736篇 |
2017年 | 633篇 |
2016年 | 977篇 |
2015年 | 1025篇 |
2014年 | 1249篇 |
2013年 | 1515篇 |
2012年 | 1719篇 |
2011年 | 1833篇 |
2010年 | 1346篇 |
2009年 | 1177篇 |
2008年 | 1424篇 |
2007年 | 1261篇 |
2006年 | 1124篇 |
2005年 | 971篇 |
2004年 | 789篇 |
2003年 | 673篇 |
2002年 | 685篇 |
2001年 | 531篇 |
2000年 | 430篇 |
1999年 | 362篇 |
1998年 | 282篇 |
1997年 | 235篇 |
1996年 | 210篇 |
1995年 | 168篇 |
1994年 | 211篇 |
1993年 | 151篇 |
1992年 | 137篇 |
1991年 | 111篇 |
1990年 | 96篇 |
1989年 | 94篇 |
1988年 | 59篇 |
1987年 | 42篇 |
1986年 | 40篇 |
1985年 | 39篇 |
1984年 | 28篇 |
1983年 | 13篇 |
1982年 | 16篇 |
1980年 | 23篇 |
1979年 | 8篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1974年 | 8篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Jong-Goo?KimEmail author Yang-Soon?Park Yeong-Keong?Ha Kyuseok?Song 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(3):723-728
The applicability of ATR-FTIR for the determination of the HDO content in heavy water (D2O) was investigated. Two groups of calibration standard solutions, of low contents (0–1 n% H2O in heavy water) and of higher contents (0–10 n% H2O in heavy water) were prepared by adding properly calculated amount of H2O to D2O by weight. The absorbances at 3400 cm−1 (ν, O–H) against the calibration standards were measured five times using two kinds of interchangeable IREs (1 bound and
9 bound reflections). And four calibration curves were obtained by linear least square fit of the measured absorbances for
the four different measurement conditions, which are (1) for low contents group using 1 bound reflection, (2) for low contents
group using 9 bound reflections, (3) for higher contents group using 1 bound reflection, (4) for higher contents group using
9 bound reflections. Determined contents (c
0) of each calibration standards for the four measurement conditions were obtained by the calibration curves and compared to
the calculated contents (c
cal). The uncertainty sources were considered when the HDO in heavy water is determined according to the procedure of this work.
The uncertainties u(c
0) of the determined contents (c
0) for the four different measurement conditions were calculated. 相似文献
993.
Structures of Chlorinated Fullerenes,IPR C96Cl20 and Non‐classical C94Cl28 and C92Cl32: Evidence of the Existence of Three New Isomers of C96
下载免费PDF全文

Prof. Dr. Shangfeng Yang Tao Wei Song Wang Dr. Ilya N. Ioffe Prof. Dr. Erhard Kemnitz Prof. Dr. Sergey I. Troyanov 《化学:亚洲杂志》2014,9(11):3102-3105
Chlorination of various HPLC fractions of C96 with a mixture of VCl4 and SbCl5 at 340–360 °C and single‐crystal X‐ray diffraction study of the products led to the identification of three new IPR isomers of C96. The C96(175) isomer forms a stable chloride, C96(175)Cl20, while chlorides of two other new isomers, C96(114) and C96(80), undergo cage shrinkage yielding C94(NC1)Cl28 and C96(NC2)Cl32 with non‐classical (NC) cages. These two NC chlorides contain, respectively, one and two heptagons flanked by pairs of fused pentagons and are stabilized by chlorine attachment to the emerging pentagon–pentagon junctions. Thus, the number of the experimentally confirmed C96 isomers has reached nine, which corroborates the empirical rule that the C6n fullerenes exhibit particularly rich isomerism. 相似文献
994.
A cobalt(11) complex containing mixed-ligands of 1,10-phenathroline(phen) and glycollic acid(GA).|Co(GA)2(phen)| was synthesized and its structure was characterized by X-ray diffraction.The interaction of the complex with DNA was investigated by electronic absorption spectra and electrochemical methods.Electronic absorption spectrum experiments showed that after interaction with DNA.the characteristic absorption peaks of |Co(GA)2(phen)| underwent hypochromic effect as well as redshift. Also,the binding strength of 3.8×104L/mol was estimated by titration method.Electrochemical assays revealed that the redox peak currents of the complex decreased obviously accompanied by a positive shift of the formal potential after association with DNA.All these results revealed that the synthesized cobalt complex bound with DNA via an intercalation mode. 相似文献
995.
996.
997.
998.
使用一维机械模板的高分辨阿达玛变换显微图像探测技术研究 总被引:1,自引:1,他引:1
阿达玛变换(HT)是一种类似于傅里叶变换(FT)的光谱调制技术,具有多通道同时检测和多通道成像能力等优点,但两者的数学模型、对光信号的调制方法和调制手段都不一样。由于HT仅涉及四则运算,而FT涉及较为复杂的三角函数和复数运算,所以HT的解码速度快于FT。在成像技术方面,HT具有直接成像的能力,而FT只能对通过其它方式获取的图像进行加工处理。 相似文献
999.
钙离子对支撑磷脂膜离子通道行为的诱导作用 总被引:2,自引:2,他引:2
将一种支撑磷脂膜--杂化双层膜(Hybridbilayermembrane,HBM)用于钙离子与磷脂作用的研究,以Fe(CN)63-为探针,发现钙离子可诱导HBM产生离子通道,且通道的打开与关闭可反复运转,并用STM观察了这一现象. 相似文献
1000.