全文获取类型
收费全文 | 750篇 |
免费 | 31篇 |
国内免费 | 3篇 |
专业分类
化学 | 599篇 |
晶体学 | 30篇 |
力学 | 12篇 |
数学 | 35篇 |
物理学 | 108篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 23篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 25篇 |
2014年 | 17篇 |
2013年 | 52篇 |
2012年 | 41篇 |
2011年 | 39篇 |
2010年 | 24篇 |
2009年 | 24篇 |
2008年 | 34篇 |
2007年 | 48篇 |
2006年 | 38篇 |
2005年 | 38篇 |
2004年 | 26篇 |
2003年 | 22篇 |
2002年 | 39篇 |
2001年 | 21篇 |
2000年 | 17篇 |
1999年 | 8篇 |
1998年 | 11篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1969年 | 2篇 |
排序方式: 共有784条查询结果,搜索用时 0 毫秒
81.
Natarajan Arumugam 《Tetrahedron》2010,66(4):969-975
Synthesis of novel pyrroloisoquinoline and indolizinoindole derivatives with β-lactam unit has been achieved by sequential intermolecular 1,3-dipolar cycloaddition reaction and Pictet-Spengler cyclization. The azomethine ylide derived from β-lactam imine of α-amino ester in the presence of silver acetate reacted with nitrostyrenes to give pyrrolidinyl β-lactam, which underwent Pictet-Spengler cyclization in presence of trifluoroacetic acid to give pyrroloisoquinolines and indolizinoindoles. 相似文献
82.
83.
84.
57Fe Mössbauer spectroscopy is used to study the interactions, geometry, and the coordination characteristics of the Fe-complexes of biopolymers such as chitosan, glucosamine, and chondritin sulfate. In addition, a computational effort is undertaken for predicting the geometries and energies of the metal complexes by the Density Functional Theory (DFT) methods as implemented in the Gaussian 2003 quantum mechanical program. Both experimental and computational results suggest that the structure of the metal complexes resemble closely the structure of the active sites of metalloenzymes in 2+ or 3+ oxidation states and is at least tetracoordinated and can possibly have six ligands. 相似文献
85.
86.
Natarajan Sathiyamoorthy Venkataramanan Ambigapathy Suvitha Hiroshi Mizuseki Yoshiyuki Kawazoe 《International journal of quantum chemistry》2015,115(21):1515-1525
The study on the absorption of toxic gases such as mustard gas by organic host is essential to the development of inexpensive detection and decontamination equipments. Using quantum chemical methods, we propose cucurbituril as an effective host to capture mustard gas. It was found that stable complexes are formed with the inclusion of the toxic gas molecules inside the cucurbituril cavity, compared with the lateral and exterior interactions. Oxygen mustard has a comparable binding energy with sulfur mustard and hence can be used during experimental investigation. Additionally, during the inclusion complex formation, the presence of heteroatoms helps the guest molecules to undergo a larger structural reorganization to get accommodated inside the cucurbituril macromolecule. Atoms‐in‐molecules analysis shows the existence of strong intermolecular CH…O bonding between the guest molecules and cucurbituril macromolecule. The presence of an intramolecular CH…Cl type of bonding accounts for the higher stabilization of sulfur mustard inside the cucurbituril macromolecule. © 2015 Wiley Periodicals, Inc. 相似文献
87.
88.
89.
Shekhar?KumarEmail author Pranay?Kumar?Sinha U.?Kamachi Mudali R.?Natarajan 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):545-549
Formation and thermal decomposition of red-oil during unit operations of nuclear fuel cycle process flowsheets is a severe
risk. In the literature, red-oil formation has been investigated thoroughly in general and in detail after Tomsk-7 incident
on 6th April 1993. However there is no information on the thermal decomposition of formed red-oil. In this work, results of
unique experiments on adiabatic thermal decomposition of red-oil, red-oil equilibrated with excess of 4N nitric acid and 100%
TBP equilibrated with excess of 4N nitric acid have been discussed. 相似文献
90.
M.?Balamurugan Shekhar?KumarEmail author U.?Kamachi Mudali R.?Natarajan 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(2):507-510
The cross sections for the 118Sn (n, α)115Cd, 120Sn (n, α)117gCd and 120Sn (n, α)117mCd reactions have been measured in the neutron energy range of 13.5–14.6 MeV using the activation technique and a coaxial
HPGe γ-ray detector. The fast neutrons were produced by the T (d, n) 4He reaction. The neutron energies in the measurements were determined by cross section ratios for 93Nb(n,2n)92mNb and 90Zr(n, 2n)89m+gZr reactions. The results of present work were discussed and compared with theoretical calculation data, measurement results
found in the literature and with the comprehensive evaluation data in ENDF/B-VII.0, CENDL-3.1, JENDL-4.0 libraries. 相似文献