全文获取类型
收费全文 | 358篇 |
免费 | 25篇 |
国内免费 | 60篇 |
专业分类
化学 | 310篇 |
晶体学 | 10篇 |
综合类 | 6篇 |
物理学 | 26篇 |
综合类 | 91篇 |
出版年
2023年 | 4篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 24篇 |
2012年 | 21篇 |
2011年 | 17篇 |
2010年 | 9篇 |
2009年 | 23篇 |
2008年 | 24篇 |
2007年 | 28篇 |
2006年 | 19篇 |
2005年 | 22篇 |
2004年 | 29篇 |
2003年 | 18篇 |
2002年 | 9篇 |
2001年 | 25篇 |
2000年 | 13篇 |
1999年 | 9篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有443条查询结果,搜索用时 93 毫秒
1.
采用溶解-反应量热法在具有恒温环境的溶解-反应热量计内,测定了[Gd(Gly)4(Im)(H2O)](ClO4)3和[Y(Gly)4(Im)(H2O)](ClO4)3两种稀土甘氨酸咪唑配合物的标准生成焓分别为(-3 461.46 ±0.22) kJ·mol-1 和(-3 926.6±0.90) kJ·mol-1. 相似文献
2.
3.
The ab initio molecular fragment approach is applied to a characterization study of the ground state of the zwitterion of glycine. Included among the properties studied are the — conformational energy surface, the electronic structure, and the magnitude and direction of the dipole moment. The results of the present study are compared to the results of other theoretical and experimental studies.This work was supported in part by the National Science Foundation, the University of Kansas, and the Upjohn Company, Kalamazoo, Michigan 49001.NSF Trainee (1969-1972).Alfred P. Sloan Research Fellow (1971–1973). 相似文献
4.
5.
Supermolecular compounds of glycine monosubstituted heteropolytungstates isomer with Keggin structure βi-K6-n(HGly)n[SiW11M(H2O)O39]·xH2O (M=Co2+, Ni2+; βi=β2, β3) were synthesized and characterized by means of elementary analysis, IR, UV, TG-DTA, X-ray diffraction, polarography and CV. The results indicate that glycin combines the electrostatic effect with heteropolytungstates isomer. The heteropoly anion still remains its Keggin structure in supermolecular compounds. The electrochemical behavior of the compound in 1 mol·L-1 HAc-NaAc shows that two redox waves correspond to two two-electron processes attributing to the reduction of [SiW11Co(H2O)O39]6-. Steady-state fluorescence spectrum shows two intenser fluorescence emission peaks in 447 nm and 486 nm appeared after the supermolecular compound being excited by the excitation wavelength in 274 nm. 相似文献
6.
Shetty Kalidas Korus roger A. Crawford Dom L. 《Applied biochemistry and biotechnology》1989,(1):825-843
Glycine max was used as a model plant cell suspension culture to establish relationships among growth kinetics, phenolics production,
elicitor action, and peroxidase activity. Timing of elictor addition through monitoring of peroxidase provided an excellent
means of optimizing yields of phenolics and reduced the time span during which phenolics were formed, negating the need for
a secondary production medium. We have also determined that calcium and other cellular effectors like polyamines and organic
osmolytes, when used in conjunction with elicitors, enhance phenolics production. Calcium directly enhanced elicitation, whereas
polyamines and other osmolytes such as glycerol and proline extended cell viability. The study also demonstrated potential
for enhancing secondary metabolite production by a combination of elicitation, cell viability stabilizers, and by addition
of nutrients at the time of elicitation. 相似文献
7.
L. A. zagorodnykh O. V. Bobreshova P. I. Kulintsov I. V. Aristov 《Russian Journal of Electrochemistry》2006,42(1):59-62
The electrical mass transfer of cations in electromembrane systems (EMS) with an MK-40 cation-exchange membrane and glycine in aqueous solutions of hydrochloric acid is studied using the method of a rotating membrane disk. Limiting current densities and limiting steps of the transport of cations in such systems are determined. Shown is the possibility of an increase in the electrical mass transfer of glycine as a consequence of the occurrence of a heterogeneous reaction of protonation of its zwitterions. The effect of the membrane surface state on the kinetic regularities of transport of cations in EMS with glycine in solutions of hydrochloric acid is exposed. 相似文献
8.
Einar Uggerud 《Theoretical chemistry accounts》1997,97(1-4):313-316
The potential energy hypersurface of protonated glycine, GH+, has been investigated. The calculated G2(MP2) value for the proton affinity (PA) of glycine, PA
calc=895kJ mol−1, is in good agreement with the experimental value which has been estimated to lie in the range 864kJ mol−1 < PA
exp
<891kJ mol−1. Ab initio quantum chemical calculations of relevant parts of the potential energy surface of GH+ give a reaction model which is consistent with the observed mass spectrometric fragmentation pattern. The lowest energy unimolecular
reactions of GH+ are two distinct processes: (1) loss of CO, which has a substantial barrier for the reverse reaction, and (2) loss of CO
plus H2O, which has no barrier for the reverse reaction.
Received: 15 November 1996 / Accepted: 6 May 1997 相似文献
9.
A Taylor dispersion tube has been used to measure mutual diffusion in aqueous solutions of glycine hydrochloride at 25°C and concentrations from 0.0005 to 0.5 M. Analysis of the dispersion profiles shows that the diffusion of glycine hydrochloride (GlyHCl) produces a subtantial additional flow of hydrochloric acid that is liberated by the dissociation: GlyH+ + Cl- Gly + H+ + Cl-. Diffusion in this system is, therefore, a ternary process described by the equations J
1(GlyHCl) = – D
11C
1 – D
12C
2 and J
2(HCl) = –D
21C
1 – D
22C
2 for the coupled fluxes of total glycine hydrochloride (1) and hydrochloric acid (2) components. The ratio D
21/D
11 of measured diffusion coefficients indicates that up to two moles of HCl are cotransported per mole of GlyHCl. Although protonated glycine diffuses with relatively mobile Cl– counterions, the main diffusion coefficient of glycine hydrochloride, D
11, is lower than or nearly identical to the diffusion coefficient of aqueous glycine. A model for the diffusion of protonated solutes is developed to interpret this result and the large coupled flows of HCl. Diffusion coefficients are also reported for the aqueous hydrochlorides of 3- and 4-aminobenzoic acids. 相似文献
10.
E. D. Matveeva T. A. Podrugina M. V. Prisyazhnoi I. N. Rusetskaya N. S. Zefirov 《Russian Chemical Bulletin》2007,56(4):798-805
Interaction of aliphatic and aromatic aldehydes and ketones with optically active L-α-amino acids or their esters in the three-component catalytic one-pot synthesis of α-aminophosphonates was studied. The
corresponding α-amino phosphonates are formed in high yields as mixtures of diastereomers.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 768–774, April, 2007. 相似文献