全文获取类型
收费全文 | 543篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
化学 | 331篇 |
晶体学 | 10篇 |
力学 | 12篇 |
数学 | 31篇 |
物理学 | 168篇 |
出版年
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 10篇 |
2014年 | 8篇 |
2013年 | 39篇 |
2012年 | 18篇 |
2011年 | 20篇 |
2010年 | 14篇 |
2009年 | 21篇 |
2008年 | 11篇 |
2007年 | 24篇 |
2006年 | 19篇 |
2005年 | 6篇 |
2004年 | 16篇 |
2003年 | 5篇 |
2002年 | 15篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1973年 | 12篇 |
1972年 | 9篇 |
1971年 | 3篇 |
1968年 | 4篇 |
1966年 | 4篇 |
1961年 | 3篇 |
排序方式: 共有552条查询结果,搜索用时 31 毫秒
101.
Bob Boyd Gareth Brenton Eddie Clayton Jonathan Curtis R. M. Elliott G. A. Errock B. N. Green R. H. Bateman Simon J. Gaskell Iwan Griffiths Zdenek Herman Philip Jonathan Rich Kondrat Mila Laušević Chris Lock Deepak Mathur John F. J. Todd Károly Vékey 《Rapid communications in mass spectrometry : RCM》2016,30(11):1253-1264
102.
Kumar Namrata Vijayshankar Soumya Pasupathi Pranav Nirmal Kumar Sundaramoorthy Elangovan Poonguzhali Rajesh Mathur Tamilarasan Krishnamurthi 《Research on Chemical Intermediates》2018,44(9):5403-5417
Research on Chemical Intermediates - In this research, soda lignin was extracted from Bambusa bambos using a soda pulping process, and interaction effects of pulping variables were statistically... 相似文献
103.
Ananta Karmakar Mushkin Basha G.T. Venkatesh Babu Murali Botlagunta Noormohamed Abdul Malik Richard Rampulla Arvind Mathur Arun Kumar Gupta 《Tetrahedron letters》2018,59(48):4267-4271
A number of cyanomethyl esters of natural/unnatural aminoacids with un-protected amino functionality were synthesized because of their synthetic and medicinal importance. Critical N-Boc deprotection methods in the presence of labile (hydrolytic sensitivity) cyanomethyl functionality were screened thoroughly and it was found that readily available 4M HCl in 1,4-dioxane solution (2–4 equiv); acetonitrile, 0?°C, 2–4?h was a suitable condition. This condition was generalized and successfully applied to a variety of alkyl, alkynyl, aryl, heteroaryl, benzyl, azido, spiro amino acid cyanomethylesters irrespective of the nature of the amine (primary or secondary) and the distance between the amine and ester group to achieve final deprotected amino esters with high yield, and purity compared to other commonly known N-protecting groups (Cbz, Fmoc, Ac, Bn, Bz etc.). It was also demonstrated that N-Boc protected aminoacid cyanomethylesters are stable enough to carry out further functionalization compared to N-unprotected counterparts. 相似文献
104.
dc conductivity as a function of temperature has been measured for as-evaporated and annealed films of amorphous Si, grown by the vacuum evaporation technique. The experimental data suggest that conduction in the higher temperature range (~175–300 K) is by the thermally activated holes in the localized states near the valence band edge while conduction in the lower temperature range (~77–175 K) is found to be thermally assisted tunnelling in the localized states near the Fermi level. The activation energy for both the processes is found to increase with an increase in the annealing temperature. The average hopping distance, calculated for conduction near the Fermi level, is also found to increase with an increase in the annealing temperature. 相似文献
105.
Yu. V. Torubaev A. A. Pasynskii P. Mathur 《Russian Journal of Coordination Chemistry》2008,34(11):799-804
A reaction of the tetramer [PhTeI]4 with Fe(CO)5 gave the monomeric complex (CO)3FeI2(Ph2Te2) (I) containing a diphenyl ditelluride molecule linked with cis-tricarbonyldiiodoiron. According to X-ray diffraction data, the Fe-Te distance in complex I (2.5724(6) ?) is appreciably shorter than the sum of the covalent Fe and Te radii and the Te-Te bond (2.7705(5) ?) is only
slightly longer than that in free Ph2Te2 (2.705(1) ?). In the reaction of Fe(CO)5 with PhTeI3, a complex with PhTeI as a ligand to the transition metal atom was obtained for the first time. Unlike free PhTeI, the resulting
complex (CO)3FeI2(PhTeI) (II) is stable in air at room temperature for several days. According to X-ray diffraction data, the ligand PhTeI (Te-C 2.126(4)
?, Te-I(3) 2.7548(5) ?) is stabilized by the coordination of tellurium to both the iron (Te-Fe 2.5451(6) ?) and iodine atoms
(Te(1)-I(1) 3.1634(5) ?). The latter coordination probably involves the vacant d orbital of tellurium and the lone electron pair on the iodide ligand.
Original Russian Text ? Yu.V. Torubaev, A.A. Pasynskii, P. Mathur, 2008, published in Koordinatsionnaya Khimiya, 2008, Vol.
34, No. 11, pp. 807–811. 相似文献
106.
Upadhyay SK Tehlan S Mathur P 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(2):347-352
A new benzimidazole-based diamide ligand-N,N'-bis(alanine-2-benzimidazolyl) hexanediamide (ABHA) has been synthesized and utilized to prepare Cu(II) complexes of general composition [Cu(ABHA)X2].nH2O,where X is an exogenous anionic ligand (X=Cl-,NO3-). Low temperature EPR spectra has been obtained that shows gparallel>gperpendicular>2.0024, indicating a tetragonal geometry in the solution state. The complexes display a quasi-reversible redox wave due to the Cu(II)/Cu(I) reduction process. E1/2 values shift anodically as NO3-相似文献
107.
We experimentally probe molecular ionization and dissociation of methane molecules in the gas phase upon their irradiation by intense pulses of white light that spans the wavelength range 500-850 nm. White light pulses are generated upon irradiation of BK7 glass by 36-fs-long pulses of intense 820 nm laser light. Comparison is made of the molecular fragmentation patterns obtained using white light that is depolarized with those obtained using single-color (820 nm) light that is highly chirped. On the basis of such comparison, we make hitherto-unavailable estimates of the in situ intensity of white light pulses. Results obtained using white light also indicate that resonances apparently do not play any role in the ionization dynamics that ensue upon irradiation by intense, broadband light; neither are the dynamics affected by the polarization properties of the 820 nm light that is used to generate the white light. 相似文献
108.
V. T. Aher M. M. Palrecha A. V. Kulkarni G. C. Shah P. K. Mathur 《Fresenius' Journal of Analytical Chemistry》1999,364(4):362-364
A differential pulse voltammetric (DPV) method is proposed for the determination of palladium in deoxo catalysts, which are
used in recombination units of the cover gas system of nuclear reactors. The electrode system consists of hanging mercury
drop electrode (HMDE)/ platinum auxillary/ Ag-AgCl reference electrode. The supporting electrolyte consists of 0.02 M diammonium
tartrate + 0.08 M ammonia-ammonium chloride buffer at pH 9.0. Fe, Cu, Pb, Ni, Co and Zn did not interfere. The interference
by Cd could be eliminated using 0.005 M EDTA. The relative standard deviation of the proposed method was about 4.0% at ∼ 0.5%
palladium content in the catalyst. The method is simple, rapid and free from any possible interferences.
Received: 8 December 1998 / Revised: 11 January 1999 / Accepted: 18 January 1999 相似文献
109.
M. S. Alam A. A. S. Awwal P. McWhorter R. Venkatesh S. Mathur M. Dugar B. Grewal 《Optics & Laser Technology》2000,32(4)
A new synthetic discriminant-function-based amplitude modulated phase-only filtering technique is proposed for scale invariant pattern recognition. This technique has been found to yield improved correlation output when compared with the alternate techniques. The proposed technique is inherently suitable for optical implementation using the currently available spatial light modulators. Simulation results confirm the effectiveness of the proposed technique. 相似文献
110.
H-atoms in C2H5OH are rearranged by strong optical fields generated by intense, 100 fs long infrared laser pulses to form new bonds that lead to the H 3 + molecular ion. This observation appears to be against the expectation that exposure of molecules to intensities of the order of 1015 W cm?2 inevitably lead to multiple ionization of molecules followed by instantaneous Coulomb explosion into fragments. The polarization dependence of the H 3 + signal and of the energy content of H 3 + ions lead to believe that H-atom rear-rangement in ethanol occurs within a single 100 fs pulse. 相似文献