全文获取类型
收费全文 | 3872篇 |
免费 | 191篇 |
国内免费 | 540篇 |
专业分类
化学 | 3623篇 |
晶体学 | 30篇 |
力学 | 52篇 |
综合类 | 4篇 |
数学 | 9篇 |
物理学 | 885篇 |
出版年
2024年 | 30篇 |
2023年 | 308篇 |
2022年 | 94篇 |
2021年 | 106篇 |
2020年 | 125篇 |
2019年 | 129篇 |
2018年 | 98篇 |
2017年 | 101篇 |
2016年 | 119篇 |
2015年 | 106篇 |
2014年 | 130篇 |
2013年 | 211篇 |
2012年 | 349篇 |
2011年 | 240篇 |
2010年 | 191篇 |
2009年 | 252篇 |
2008年 | 235篇 |
2007年 | 250篇 |
2006年 | 202篇 |
2005年 | 163篇 |
2004年 | 172篇 |
2003年 | 121篇 |
2002年 | 88篇 |
2001年 | 95篇 |
2000年 | 66篇 |
1999年 | 74篇 |
1998年 | 84篇 |
1997年 | 77篇 |
1996年 | 77篇 |
1995年 | 51篇 |
1994年 | 37篇 |
1993年 | 43篇 |
1992年 | 38篇 |
1991年 | 30篇 |
1990年 | 19篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 1篇 |
1975年 | 14篇 |
1968年 | 1篇 |
排序方式: 共有4603条查询结果,搜索用时 62 毫秒
31.
32.
Paolo Zatta Tamas KissMario Suwalsky Guy Berthon 《Coordination chemistry reviews》2002,228(2):271-284
Aluminium has been known as a neurotoxic agent to experimental animals since the last century (Arch. Exp. Pharmacol. 40 (1897) 98). However, great interest arose in it bioinorganic chemistry as well biology when it was demonstrated to be the causative agent in pathologies related to the long-term dialysis treatment of uremic subjects with renal failure (Life Chem. 11 (1994) 197), and as a potential etiopathogenic cofactor for several neurodegenerative diseases. The inorganic biochemistry of aluminium is still largely to be discovered. In this review the pro-oxidative property of aluminium toward biological membrane will be presented and its implications in involvement in human pathology will be discussed in an interdisciplinary frame from the bioinorganic point of view. 相似文献
33.
Fe3O4/ chitosan magnetic microspheres of 50 to 80 滋m were prepared using the inverse phase emulsion dispersion and chemical crosslinking technology, and then modified with ethylenediamine for use in the adsorption of heavy metal ions. The adsorption properties of the modified Fe3O4/chitosan toward Cu2+, Cd2+ and Ni2+ were investigated. It was found that the adsorption capacities of Cu2+ and Ni2+ increased with pH, and a maximum adsorption for Cd2+ occurred at pH=3. The saturated adsorption capacities calculated by Langmuir isotherms were 54.3 mg·g-1 for Cu2+, 20.4 mg·g-1 for Cd2+, and 12.4 mg·g-1 for Ni2+, respectively. The adsorption kinetics were well described by pseudo-second-order equation models. The experimental results showed that the Fe3O4/chitosan modified with ethylenediamine presented higher adsorption selectivity for Cu2+ than for Cd2+ and Ni2+ in all studied pH ranges. 相似文献
34.
金属配合物高效液相色谱法测定人发和血清中锌,钴,铜的含量 总被引:1,自引:0,他引:1
选用8-羟基喹啉为配合剂,经柱前衍生后高效波相色谱法分离测定,建立了人发和血清中微量元素锌、钴、铜的含量测定方法,该法配合产物稳定性好,标准曲线的线性范围锌、铜均为0.8~4.0mg/L,钴为0.1~2.0mg/L,相关系数均0.999以上,批内、批间相对标准偏差均小于5%,加样回收率锌为(100.3±0.47)%,钴为(98.9±2.07)%,铜为(100.9±0.65)%。 相似文献
35.
36.
将酞菁锰(MnPc)掺入阳离子表面活性剂双十二烷基二甲基溴化铵(DDAB)的氯仿溶液,并涂布于热解石墨电极表面,待氯仿挥发后即制得MnPc-DDAB薄膜电极。循环伏安实验表明,在KBr溶液中,该薄膜电极有两对还原氧化峰,第一对峰的Epc1=-0.27V,Epa1=0.01V;第二对峰的Epc2=-0.76V,Epa2=-0.62V(vs.SCE)。本文着重探讨了第二对峰的电化学行为,估计了该体系的电荷传递扩散系数Dct和表观非均相电极反应速率常数K0′等电化学参数,并可将该薄膜电极用于催化三氯乙酸的电化学还原。 相似文献
37.
过渡金属酞等配合物(MPC)用手均相液相氧化中作催化剂已有不少报导,象许多均相催化剂一样,MPC用于均相反应存在着难于从反应体系中分离出来的问题.把均相配合物催化剂固载在无机氧化物如硅股或有机高分子载体上是解决这一问题的一种方法.我们曾尝试把MP。固载在分子筛载体和硅胶载体上,并用ESR研究其对O2的活化作用[1,2].本文报导MPc通过共价键键联固载在SiO2上,并研究其对O2的活化作用.1实验部分1.1试剂HSIC13为日本东京化成株式会社产品,二级试剂·发烟硫酸(SO。质量分数大于20%)为分析纯试剂.PCl5为化学纯试… 相似文献
38.
Cycloaddition of carbon dioxdie and propylene oxide to propylene carbonate catalyzed by tetra-tert-butyl metal phthalocyanine in the presence of tributylamine(TBA) shows higher yield than catalyzed by unsubstituted metal phthalocyanine.Comparing different catalysts of diverse metals,(t-Bu)4PcMg is more active than (t-Bu)PcFe ,But(t-Bu)4PcCo and (t-Bu)4PcNi only have low catalytic activities towards the reaction.Moreover,the yield will increase as the temperature increases. 相似文献
39.
Xiaoqiang Li Stefan Miltschitzky Andreas Grauer Veronika Michlov Burkhard Knig 《Tetrahedron》2006,62(52):12191-12196
The synthesis and peptide-binding properties of a Zn(II)nitrilotriacetate complex substituted with pyrimidine hydrazine amides are reported. The metal complex provides millimolar binding affinity in aqueous buffer to peptides bearing N-terminal His. The pyrimidine heterocycles intermolecularly interact with the bound peptide and quench the emission of nearby Trp residues by energy transfer. 相似文献
40.
This is the first report on the determination of proteins with tetra-substituted sulphonated aluminum phthalocyanine (AlS4Pc) by resonance light-scattering (RLS). At pH 3.0, the weak RLS of AlS4Pc can be enhanced by the addition of proteins. Based on this, a novel quantitative method has been developed for the determination of proteins in aqueous solutions. Under optimal conditions, the linear ranges of the calibration curves were 0.050–2.0 μg ml−1 for both human serum albumin (HSA) and human r-IgG. The detection limits were 12.7 ng ml−1 for HSA and 16.1 ng ml−1 for human r-IgG. The method has been applied to the analysis of total protein in human serum samples collected from the hospital and the results were in good agreement with those reported by the hospital, which indicates that the method presented here is not only sensitive, simple, but also reliable and suitable for practical applications. 相似文献