全文获取类型
收费全文 | 163篇 |
免费 | 10篇 |
专业分类
化学 | 119篇 |
力学 | 3篇 |
数学 | 10篇 |
物理学 | 41篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 6篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有173条查询结果,搜索用时 31 毫秒
51.
Madhab C. Das Parimal K. Bharadwaj Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(17):5070-5077
The porous coordination polymer ({[Mn(L)H2O](H2O)1.5(dmf)}n, 1 ) (DMF=N,N‐dimethylformamide) exhibits variety of substitution reactions along with movement of lattice DMF molecule depending upon bulkiness of the external guest molecules. If pyridine or 4‐picoline is used as a guest, both lattice and coordinated solvent molecules are simultaneously substituted (complexes 6 and 7 , respectively). If a bulky guest like aniline is used, a partial substitution at the metal centers and full substitution at the channels takes place (complex 8 ). If the guest is 2‐picoline (by varying the position of bulky methyl group with respect to donor N atom), one MnII center is substituted by 2‐picoline, whereas the remaining center is substituted by a DMF molecule that migrates from the channel to the metal center (complex 9 ). Here, the lattice solvent molecules are substituted by 2‐picoline molecules. For the case of other bulky guests like benzonitrile or 2,6‐lutidine, both the metal centers are substituted by two DMF molecules, again migrating from the channel, and the lattice solvent molecules are substituted by these guest molecules (complex 10 and 11 , respectively). A preferential substitution of pyridine over benzonitrile (complex 12 ) at the metal centers is observed only when the molar ratio of PhCN:Py is 95:5 or less. For the case of an aliphatic dimethylaminoacetonitrile guest, the metal centers remain unsubstituted (complex 13 ); rather substitutions of the lattice solvents by the guest molecules take place. All these phenomena are observed through single crystal to single crystal (SC–SC) phenomena. 相似文献
52.
Reynolds TE Bharadwaj AR Scheidt KA 《Journal of the American Chemical Society》2006,128(48):15382-15383
Silyloxyallenes derived from alpha-hydroxypropargylsilanes undergo efficient addition to aldehydes with catalytic amounts of Lewis acids. The allenes are accessed from the corresponding propargylsilanes in a base-catalyzed 1,2-Brook rearrangement/SE2' process. Enantioenriched propargylsilanes are synthesized by a new zinc-promoted addition of alkynes to acylsilanes in up to 74% ee. This work demonstrates that conversion to the silyloxyallenes occurs with minimal erosion in optical activity. The use of a chiral chromium(III) Lewis acid effects the catalytic asymmetric addition of racemic silyloxyallenes to aromatic aldehydes in up to 92% ee. The overall reaction is broad in scope and accommodates a wide variety of aromatic and aliphatic substituents on both the propargylsilane and aldehyde. 相似文献
53.
Adams J Aggarwal MM Ahammed Z Amonett J Anderson BD Arkhipkin D Averichev GS Badyal SK Bai Y Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellingeri-Laurikainen A Bellwied R Berger J Bezverkhny BI Bharadwaj S Bhasin A Bhati AK Bhatia VS Bichsel H Bielcik J Bielcikova J Billmeier A Bland LC Blyth CO Blyth SL Bonner BE Botje M Boucham A Bouchet J Brandin AV Bravar A Bystersky M Cadman RV Cai XZ Caines H Sánchez MC Catu O Cebra D Chajecki Z Chaloupka P Chattopadhyay S Chen HF 《Physical review letters》2006,97(15):152302
Measurements of the production of forward pi0 mesons from p + p and d + Au collisions at square root sNN=200 GeV are reported. The p + p yield generally agrees with next-to-leading order perturbative QCD calculations. The d + Au yield per binary collision is suppressed as eta increases, decreasing to approximately 30% of the p + p yield at eta =4.00, well below shadowing expectations. Exploratory measurements of azimuthal correlations of the forward pi0 with charged hadrons at eta approximately 0 show a recoil peak in p + p that is suppressed in d + Au at low pion energy. These observations are qualitatively consistent with a saturation picture of the low-x gluon structure of heavy nuclei. 相似文献
54.
Mukul C. Chakravorti Mukti B. Sarkar Parimal K. Bharadwaj 《Transition Metal Chemistry》1981,6(4):211-214
Summary The compounds Ni(NH3)4(ReO4)2 and Ni(py)4(ReO4)2 prepared by reacting Ni(ReO4)2 with aqueous ammonia or pyridine, when heated at 150° give Ni(NH3)2(ReO4)2 and Ni(py)2(ReO4)2 respectively. The kinetics of the thermal decomposition of Ni(NH3)2(ReO4)2 has been studied. I.r., Raman and electronic spectra, x-ray powder diffraction and magnetic susceptibility measurements (at different temperatures) of the four compounds indicate that they are tetragonal complexes of NiII containing coordinated perrhenate. 相似文献
55.
56.
We have developed two methods for the nonseparable elliptic equations of the type ?[middot](a?u)=f, based on the extension of the symmetric marching technique developed in [2]. In method I, symmetric marching has been applied to carry out the iterations in the iterative scheme developed by Concus and Golub [3]. Method II is a noniterative method based on the direct extension of symmetric marching to the above problem. Numerical results are given to illustrate the behavior of the two methods. 相似文献
57.
Adams J Aggarwal MM Ahammed Z Amonett J Anderson BD Arkhipkin D Averichev GS Badyal SK Bai Y Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellingeri-Laurikainen A Bellwied R Berger J Bezverkhny BI Bharadwaj S Bhasin A Bhati AK Bhatia VS Bichsel H Bielcik J Bielcikova J Billmeier A Bland LC Blyth CO Blyth SL Bonner BE Botje M Boucham A Bouchet J Brandin AV Bravar A Bystersky M Cadman RV Cai XZ Caines H Calderón de la Barca Sánchez M Castillo J Catu O Cebra D Chajecki Z 《Physical review letters》2005,95(12):122301
We report on the first measurement of elliptic flow v2(pT) of multistrange baryons Xi- +Xi+ and Omega- + Omega+ in heavy-ion collisions. In minimum-bias Au+Au collisions at square root of s(NN)=200 GeV, a significant amount of elliptic flow, comparable to other nonstrange baryons, is observed for multistrange baryons which are expected to be particularly sensitive to the dynamics of the partonic stage of heavy-ion collisions. The pT dependence of v2 of the multistrange baryons confirms the number of constituent quark scaling previously observed for lighter hadrons. These results support the idea that a substantial fraction of the observed collective motion is developed at the early partonic stage in ultrarelativistic nuclear collisions at the Relativistic Heavy Ion Collider. 相似文献
58.
59.
60.
Geetika Borah Devajani Boruah Gayatri Sarmah Saitanya K. Bharadwaj Utpal Bora 《应用有机金属化学》2013,27(12):688-694
The reaction of N‐methylimidazole (N‐MeIm) and N‐butylimidazole (N‐BuIm) with the complexes [PdCl2(PPh2py–P,N)] and [PdCl2(PPh2Etpy–P,N)] in the presence of NH4PF6 under N2 at room temperature afforded four new cationic Pd(II) complexes [PdCl(PPh2py–P,N)(N‐MeIm)](PF6) ( 1 ), [PdCl(PPh2py–P,N)(N‐BuIm)](PF6) ( 2 ), [PdCl(PPh2Etpy–P,N)(N‐MeIm)](PF6) ( 4 ) and [PdCl(PPh2Etpy‐P,N)(N‐BuIm)](PF6) ( 5 ) in good yields, where PPh2py is 2‐(diphenylphosphino)pyridine and PPh2Etpy is 2‐{2‐(diphenylphosphino)ethyl}pyridine). The complexes were fully characterized. The catalytic activities of these complexes were investigated for Suzuki–Miyaura cross‐coupling reactions at room temperature. Complex 2 exhibited excellent activity compared to other analogs. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献