全文获取类型
收费全文 | 2037篇 |
免费 | 59篇 |
国内免费 | 1篇 |
专业分类
化学 | 1117篇 |
晶体学 | 39篇 |
力学 | 73篇 |
数学 | 124篇 |
物理学 | 744篇 |
出版年
2023年 | 12篇 |
2022年 | 24篇 |
2021年 | 26篇 |
2020年 | 40篇 |
2019年 | 35篇 |
2018年 | 42篇 |
2017年 | 31篇 |
2016年 | 78篇 |
2015年 | 43篇 |
2014年 | 63篇 |
2013年 | 130篇 |
2012年 | 135篇 |
2011年 | 133篇 |
2010年 | 82篇 |
2009年 | 68篇 |
2008年 | 117篇 |
2007年 | 100篇 |
2006年 | 92篇 |
2005年 | 100篇 |
2004年 | 73篇 |
2003年 | 47篇 |
2002年 | 47篇 |
2001年 | 40篇 |
2000年 | 26篇 |
1999年 | 18篇 |
1998年 | 12篇 |
1997年 | 14篇 |
1996年 | 26篇 |
1995年 | 31篇 |
1994年 | 20篇 |
1993年 | 30篇 |
1992年 | 17篇 |
1991年 | 19篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 17篇 |
1985年 | 35篇 |
1984年 | 16篇 |
1983年 | 14篇 |
1982年 | 29篇 |
1981年 | 25篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1975年 | 9篇 |
1974年 | 14篇 |
1973年 | 10篇 |
1955年 | 12篇 |
排序方式: 共有2097条查询结果,搜索用时 15 毫秒
951.
Ananda K. Banerjee Miss Abha Misra Arup K. Basak Debabrata Banerjea 《Transition Metal Chemistry》1982,7(5):239-242
Summary In aqueous acid media the title complexes undergo decomposition ultimately forming cobalt(II). Detailed analysis of the kinetic data reveals that the reactions proceed in two consecutive stages, the initial step being the faster one. Evidence has been presented that the initial faster step involves aquation releasing one NO
2
–
ligand and forming an aquodinitro complex, which subsequently undergoes a slower intramolecular redox decomposition into Co2+. Each step, on the other hand, has been found to consist of two concurrent paths,viz. spontaneous and acid catalysed, respectively. Activation parameters corresponding to all these specific rate constants have been evaluated and a plausible mechanism for the overall reaction has been proposed.On leave from Agra College, Agra, India. 相似文献
952.
Molecular structure of phosphine in a number of excited electronic states is studied using the method of hole-potential within
the basic framework of CNDO/2 theory. Effects of including 3d-functions of phosphorus in the basis set on computed molecular geometries, transition energies and inversion barriers in
the excited states have been investigated. An attempt is made to rationalise qualitatively the structural changes in the excitedstate
in terms of Walsh-type correlation diagram constructed with the eigenvalues of the Fock operator in theV
N-1
potential model. A simple orbital model for predicting the nature of structural changes in the excited states is proposed. 相似文献
953.
954.
955.
H.J. Behrend Ch. Chen H. Fenner J.H. Field V. Schr?der H. Sindt G. DAgostini W.-D. Apel S. Banerjee J. Bodenkamp D. Chrobaczek J. Engler G. Flügge D.C. Fries W. Fues K. Gamerdinger G. Hopp F. Pierre 《Physics letters. [Part B]》1982,114(5):378-382
From the two-photon exchange processes e+e? → e+e?η' (958) → e+e??0γ and e+e? → e+e?A2 (1310) → e+e?π+π?π0 observed using the CELLO detector at PETRA the radiative widths of the η' and A2 have been determined with the results: Γγγ(η') = 5.4 ± 1.0[stat.] ± 0.7[syst.] keV; Γγγ(A2) = 0.59 ± 0.14[stat.] ?0.08+0.31[syst.] keV. 相似文献
956.
Madhava B. Mallia Anupam Mathur Rohit Sharma Chandan Kumar H. D. Sarma Sharmila Banerjee Ashutosh Dash 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(3):1203-1210
Conventional 99mTc-radiopharmaceuticals for the detection of tumor hypoxia generally possess a single nitroimidazole moiety. Herein, we report the synthesis and evaluation of a 99mTc-complex with three-nitroimidazole moieties in an attempt to improve hypoxic cell detection. Isocyanide derivative of metronidazole (MetroNC) was synthesized and subsequently radiolabeled with [99mTc(CO)3(H2O)3]+ precursor complex, wherein the three labile water molecules were replaced with MetroNC ligand to form a pseudo-octahedral [99mTc(CO)3(MetroNC)3]+ complex. Analysis of corresponding Re(CO)3-analog prepared in macroscopic scale confirmed the formation of expected complex. Cyclic voltammetric studies of [Re(CO)3(MetroNC)3]+ complex showed no significant change in single-electron reduction potential (SERP) of MetroNC ligand (??0.96 V) upon forming the [Re(CO)3(MetroNC)3]+ complex (??0.90 V). In vitro studies in Chinese hamster ovary (CHO) cells showed three-fold preferential accumulation of [99mTc(CO)3(MetroNC)3]+ complex in hypoxic cells over normoxic cells. Biodistribution studies of [99mTc(CO)3(MetroNC)3]+ complex in Swiss mice bearing fibrosarcoma tumor showed tumor uptake and steady retention till 60 min post injection. Present study constitutes a novel design approach towards development of a 99mTc-radiopharmaceutical for hypoxia imaging application, which could be extended to other potential nitroimidazole ligands. 相似文献
957.
S. Lahiri Sh. Banerjee N. R. Das 《Journal of Radioanalytical and Nuclear Chemistry》1997,218(2):215-218
A radiochemical charged particle activation procedure has been developed for the production and separation of the carrier free radioisotopes,65Zn and66,67,68Ga. The carrier free radioisotopes produced by the irradiation of a pure copper foil with 50 MeV -particle beam through the nuclear reactions, (, pxn), (,pxn) and (,xn), have been quantitatively separated from the activated copper matrix from an aqueous hydrochloric acid and an alkaline solution using the liquid cation exchanger HDEHP, as an extractant. Detection of different radionuclides in the activated copper target and verification of their purity at different stages of their LLX separation have been performed by -ray spectrometric studies. 相似文献
958.
959.
T. Banerjee S. Chaudhuri M. Moore S. Ray P.S. Chatterjee P. Roychowdhury 《Journal of chemical crystallography》1999,29(12):1281-1286
Both 5-amino-1-(2-hydroxyethyl)imidazole-4-carboxamide (AHIC) and 5-amino-1-(2-chloroethyl)-4-cyanoimidazole (ACCI) have been synthesized and crystallized in the monoclinic space group P21/c, Z = 4, with a = 8.420(2), b = 9.759(2), c = 10.583(2) Å, = 111.80(2)° for AHIC and a = 6.139(1), b = 8.522(2), c = 15.156(3) Å, = 96.71(2)° for ACCI. Differences in the molecular geometries of the two compounds are attributed to the differences in the substituents at the 1- and 4-positions of the imidazole ring. The molecular conformation of AHIC is stabilized by intramolecular hydrogen bonding between the 5-amino and the vicinal carboxamide moiety, resulting in an extended planar structural pattern. The presence of the cyano group in the 4-position of ACCI prevents the formation of such an intramolecular hydrogen bond. Both the crystal structures are stabilized by networks of intermolecular hydrogen bonds. 相似文献
960.
Alexopoulos T Allen C Anderson EW Balamurali V Banerjee S Beery PD Bhat P Bishop JM Biswas NN Bujak A Carmony DD Carter T Choi Y Cole P DeBonte R DeCarlo V Erwin AR Findeisen C Goshaw AT Gutay LJ Hirsch AS Hojvat C Jennings JR Kenney VP Lindsey CS Loomis C LoSecco JM McMahon T McManus AP Morgan N Nelson K Oh SH Porile NT Reeves D Rimai A Robertson WJ Scharenberg RP Stampke SR Stringfellow BC Thompson M Turkot F Walker WD Wang CH Warchol J Wesson DK Zhan Y 《Physical review letters》1993,71(10):1490-1493