全文获取类型
收费全文 | 508篇 |
免费 | 26篇 |
国内免费 | 1篇 |
专业分类
化学 | 327篇 |
晶体学 | 2篇 |
力学 | 16篇 |
数学 | 94篇 |
物理学 | 96篇 |
出版年
2022年 | 5篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 15篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 13篇 |
2015年 | 17篇 |
2014年 | 17篇 |
2013年 | 28篇 |
2012年 | 39篇 |
2011年 | 43篇 |
2010年 | 26篇 |
2009年 | 19篇 |
2008年 | 27篇 |
2007年 | 36篇 |
2006年 | 24篇 |
2005年 | 31篇 |
2004年 | 23篇 |
2003年 | 13篇 |
2002年 | 18篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1970年 | 3篇 |
1966年 | 2篇 |
1923年 | 2篇 |
1913年 | 2篇 |
排序方式: 共有535条查询结果,搜索用时 15 毫秒
451.
Cabooter D Billen J Terryn H Lynen F Sandra P Desmet G 《Journal of chromatography. A》2008,1178(1-2):108-117
The pressure-drop characteristics of six sub-2 microm columns of three different manufacturers but with the same surface chemistry (C(18)) have been studied using the recently introduced total pore blocking method for the determination of the external porosity and by using scanning electron microscopy pictures to measure the actual size of the particles. Having used the Sauter-mean particle size to correctly account for the particle size spread, and having corrected for the influence of the intra-particle porosity, it was found that all columns yielded Kozeny-Carman constant (f(KC)) values close to 180, in agreement with the theory. This agreement could subsequently be used to quantify how the different system parameters such as mean particle size, packing density and intra-particle porosity (all tending to vary significantly from manufacturer to manufacturer) each contributes to the observed total bed permeability. Small (upward) deviations from the f(KC)=180-value could be correlated to a larger width of the particle size distribution, and more notably to the existence of a high size ratio of the largest to the smallest particles present in the particle batches. 相似文献
452.
Chaur MN Melin F Athans AJ Elliott B Walker K Holloway BC Echegoyen L 《Chemical communications (Cambridge, England)》2008,(23):2665-2667
A reactivity study of the higher TNT EMFs of gadolinium is reported here showing that the reactivity substantially decreases when the fullerene cage gets larger. 相似文献
453.
Stereospecific styrene enchainment at a titanium site within a helical ligand framework: evidence for the formation of homochiral polystyrene 总被引:1,自引:0,他引:1
454.
455.
Dr. Lambert Sicard Dr. Frederic Lafolet Dr. Martial Boggio-Pasqua Dr. Christophe Bucher Prof. Guy Royal Dr. Saioa Cobo 《Chemphyschem》2022,23(9):e202200004
The optical and redox properties of a methyl pyridinium appended 1,2-dithienylethene photochromic derivative have been thoroughly investigated. A complex multi-step photo/redox mechanism is proposed for the closed isomer on the ground of spectro-electrochemical and theoretical data. The generated compounds are not stable over the time because of chemical reactions associated to the redox processes and a new dithienylethene derivative incorporating a seven-membered ring has been isolated and characterized. 相似文献
456.
Christopher M. Ryan Puneet Souda Frederic Halgand David T. Wong Joseph A. Loo Kym F. Faull Julian P. Whitelegge 《Journal of the American Society for Mass Spectrometry》2010,21(6):908-917
A hybrid linear ion-trap Fourier-transform ion cyclotron resonance mass spectrometer was used for top-down characterization
of the abundant human salivary cystatins, including S, S1, S2, SA, SN, C, and D, using collisionally activated dissociation
(CAD) after chromatographic purification of the native, disulfide intact proteins. Post-translational modifications and protein
sequence polymorphisms arising from single nucleotide polymorphisms (SNPs) were assigned from precursor and product ion masses
at a tolerance of 10 ppm, allowing confident identification of individual intact mass tags. Cystatins S, S1, S2, SA, and SN
were cleaved of a N-terminal 20 amino acid signal peptide and cystatin C a 26-residue peptide, to yield a generally conserved
N-terminus. In contrast, cystatin D isoforms with 24 and 28 amino acid residue N-terminal truncations were found such that
their N-termini were not conserved. Cystatin S1 was phosphorylated at Ser3, while S2 was phosphorylated at Ser1 and Ser3,
in agreement with previous work. Both cystatin D isoforms carried the polymorphism C46R (SNP: rs1799841). The 14,328 Da isoform
of cystatin SN previously assigned with polymorphism P31L due to a SNP (rs2070856) was found only in whole saliva. Parotid
secretions contained no detectable cystatins while whole saliva largely mirrored the contents of submandibular/sublingual
(SMSL) secretions. With fully characterized cystatin intact mass tags it will now be possible to examine the correlation between
the abundance of these molecules and human health and disease. 相似文献
457.
458.
459.
460.
We prove the linear and nonlinear instability of the line solitary water waves with respect to transverse perturbations. 相似文献