全文获取类型
收费全文 | 2021篇 |
免费 | 93篇 |
国内免费 | 125篇 |
专业分类
化学 | 794篇 |
晶体学 | 30篇 |
力学 | 111篇 |
综合类 | 11篇 |
数学 | 984篇 |
物理学 | 309篇 |
出版年
2024年 | 5篇 |
2023年 | 32篇 |
2022年 | 44篇 |
2021年 | 36篇 |
2020年 | 55篇 |
2019年 | 64篇 |
2018年 | 47篇 |
2017年 | 68篇 |
2016年 | 69篇 |
2015年 | 55篇 |
2014年 | 100篇 |
2013年 | 142篇 |
2012年 | 84篇 |
2011年 | 101篇 |
2010年 | 95篇 |
2009年 | 172篇 |
2008年 | 133篇 |
2007年 | 133篇 |
2006年 | 92篇 |
2005年 | 75篇 |
2004年 | 69篇 |
2003年 | 60篇 |
2002年 | 56篇 |
2001年 | 59篇 |
2000年 | 50篇 |
1999年 | 36篇 |
1998年 | 41篇 |
1997年 | 46篇 |
1996年 | 24篇 |
1995年 | 29篇 |
1994年 | 22篇 |
1993年 | 11篇 |
1992年 | 16篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有2239条查询结果,搜索用时 15 毫秒
81.
Jose Gracia Mauro Fianchini Chiara Biz Victor Polo Roberto Gómez 《Current Opinion in Electrochemistry》2021
Strongly correlated catalysts can be understood from precise quantum approximations. Incorporating properly electronic correlations thus let’s define Spin rules in catalysis, opening a new door towards optimum compositions for the most important reactions for a sustainable future. 相似文献
82.
83.
It is shown that for , there exists an optimal packing with triples on points that contains no Pasch configurations. Furthermore, for all (mod 6), there exists a pairwise balanced design of order , whose blocks are all triples apart from a single quintuple, and that has no Pasch configurations amongst its triples. 相似文献
84.
A new model of nonlinear electrodynamics with two parameters is investigated. We also consider a model with one dimensional parameter. It was shown that the electric field of a point-like charge is not singular at the origin and there is the finiteness of the static electric energy of point-like charged particle. We obtain the canonical and symmetrical Belinfante energy–momentum tensors and dilatation currents. It is demonstrated that the dilatation symmetry and dual symmetry are broken in the models suggested. We have calculated the static electric energy of point-like particles. 相似文献
85.
Egbert Müller Judith Vajda Djuro Josic Tim Schröder Romain Dabre Tim Frey 《Journal of separation science》2013,36(8):1327-1334
An essential part of the modulation of protein‐binding capacity in hydrophobic interaction chromatography is the buffer‐salt system. Besides using “single” electrolytes, multicomponent electrolyte mixtures may be used as an additional tool. Both the protein solubility and the binding capacity depend on the position of a salt in the so‐called Hofmeister series. Specific interactions are observed for an individual protein‐salt combination. For salt mixtures, selectivity, recovery, and binding capacity do not behave like for the single salts that are positioned in between the two mixed components in the Hofmeister series, as the continuous correlation would suggest. Thus, finding strategies for mixed salts could potentially lead to improved capacities in hydrophobic interaction chromatography. Mixtures of ammonium sulfate, sodium citrate, sodium sulfate, sodium chloride, sodium acetate, and glycine were used to investigate the binding capacities for lysozyme and a monoclonal antibody on various hydrophobic resins. Resin capacity for two investigated proteins increases when mixtures consisting of a chaotropic and a kosmotropic salt are applied. It seems to be related to the rather basic isoelectric points of the proteins. 相似文献
86.
Mohsin Ahmad Bhat Aijaz Ahmad Dar Adil Amin 《Journal of Dispersion Science and Technology》2013,34(4):514-520
Micellization parameters, critical micelle concentration (cmc), degree of counterion dissociation (α), aggregation number (n), critical packing parameter, and hydrophobic core volume of Dodecylpyridinium chloride (DPC) micelles were determined in presence of varying concentrations of sodium chloride (NaCl), sodium acetate (SAc), sodium propionate (SPr), ethylammonium chloride (EACl), diethylammonium chloride (DEACl), tetraethylammonium chloride (TEACl), and propylammonium chloride (PACl) through conductometric investigations at 298.15 K. The resulting data suggests that both counter and coions affect the cmc values‐cmc depressing tendency of the salts varies in order PACl≈NaCl>EACl>DEACl>TEACl>SPr>SAc, while the degree of counterion dissociation is dependent on the nature and concentration range of the added salt. Increasing salt concentration increases the relative hydrophobic volume of the micelles and coion has not much effect on aggregation number. 相似文献
87.
Dr. Thien H. Ngo Dr. Hülya Berndt Dr. Michael Wilsdorf Prof. Dr. Hans‐Ulrich Reissig 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(45):15155-15165
The dipeptide isostere 5‐aminothiophene carboxylic acid has been combined with L ‐phenylalanine moieties to provide linear and cyclic hybrid oligopeptides. A suitable protecting group strategy and appropriate coupling methods have been developed to guarantee a high degree of enantiopurity of the resulting amides. Cyclic tetraamides have been efficiently obtained by macrocyclization of the linear derivatives. In the case of racemized cyclization precursors, two diastereomeric macrocycles (S,S/R,R and meso) have been isolated. Their crystal structures show clear effects of the stereogenic centers on the ring conformations and molecular packing. 相似文献
89.
90.
Martin Franc Jana Sobotníková Pavel Coufal Zuzana Bosáková 《Journal of separation science》2014,37(17):2278-2283
Fused‐silica capillary columns for high‐performance liquid chromatography with 320 and 250 μm inner diameter were prepared by slurry packing with 5 and 3 μm Nucleosil C18 stationary phase. Different types of mechanical and monolithic outlet frits were used and their influence on the resulting column performance was evaluated. Columns with quartz wool exhibited symmetrical peaks and low theoretical plate height, and the preparation time was short. The performance of monolithic frits varied based on type of monolith, length of the frit, and silanization procedure. The best frit performed similarly to the quartz wool ones, but the preparation took several hours. Their main advantage lies in the possibility of on‐column detection, because the detection window can be burnt immediately behind the frit. 相似文献