全文获取类型
收费全文 | 380篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
化学 | 245篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 1篇 |
物理学 | 140篇 |
出版年
2023年 | 7篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 11篇 |
2019年 | 8篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 6篇 |
2012年 | 13篇 |
2011年 | 16篇 |
2010年 | 15篇 |
2009年 | 13篇 |
2008年 | 22篇 |
2007年 | 32篇 |
2006年 | 17篇 |
2005年 | 20篇 |
2004年 | 18篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 12篇 |
2000年 | 18篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1990年 | 3篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 10篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1933年 | 1篇 |
排序方式: 共有395条查询结果,搜索用时 187 毫秒
141.
We introduce a novel combination of boronic acid affinity chromatography with lectin affinity chromatography, dubbed as boronic
acid–lectin affinity chromatography (BLAC). Concanavalin A and wheat germ agglutinin lectins were mixed with the pesudo-lectin
boronic acid to form the BLAC affinity column and their performance was evaluated with standard glycoproteins. Optimization
of the binding and elution buffers for the BLAC system is described. The BLAC columns were employed to isolate glycoproteins
of interest using both selective and/or combined elution. 相似文献
142.
143.
Pit van Bonn Prof. Dr. Carsten Bolm Dr. José G. Hernández 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2576-2580
Esters and amides were mechanochemically prepared by palladium-catalyzed carbonylative reactions of aryl iodides by using molybdenum hexacarbonyl as a convenient solid carbonyl source and avoiding a direct handling of gaseous carbon monoxide. Real-time monitoring of the mechanochemical reaction by in situ pressure sensing revealed that CO is rapidly transferred from Mo(CO)6 to the active catalytic system without significant release of molecular carbon monoxide. 相似文献
144.
Zou X Zhong L Liu D Yang B Lou Y Peng J Rainer M Feuerstein I Muhammad NU Huck CW Bonn GK Yin Y 《Analytical and bioanalytical chemistry》2011,400(3):747-756
In this study, we describe characterization of the human plasma proteome based on analysis with multifunctional chitosan-GMA-IDA-Cu(II) nanospheres. Chitosan-GMA-IDA-Cu(II) nanospheres with diameters of 20 to 100?nm have unique properties due to multifunctional chemical moieties, high surface area, high capacity, good dispersibility in buffer solution as well as good biocompatibility and chemical stability which improves their specific interaction with peptides and proteins of the human plasma using different binding buffers. Combining these chitosan-GMA-IDA-Cu(II) nanospheres with MS spectrometry results in a novel strategy which should make it possible to characterize the plasma proteome in a single test. Peptides and proteins adsorbed on the nanosphere can be directly detected by MALDI-TOF-MS. The eluted lower molecular weight peptides and proteins are identified by nano-LC-ESI-MS/MS. A total of 842 unique LMW peptides and 1,682 human unredundant proteins IDs were identified in two different binding buffers, which included relatively low-level proteins (e.g., pg/mL of IL3 Interleukin-3) co-distributed with high-abundance proteins (e.g., 35?C55?mg/mL level serum albumin). As such, this nanosphere technique selectively enabled the identification of proteins over a dynamic range of greater than 8 orders of magnitude. Considering this capacity for selective enrichment of peptides and proteins in human plasma, and the large number of LMW peptides and proteins which can be identified, this method promises to accelerate discovery of biomarkers for clinical application. Figure
The human plasma proteome based on analysis with multifunctional chitosan-GMA-IDA-Cu(II) nanospheres which improves their specific interaction with peptides and proteins of the human plasma using different binding buffers. Combining these chitosan-GMA-IDA-Cu(II) nanosphere with MS spectrometry, results in a novel strategy which should make it possible to characterize the plasma proteome in a single test. 相似文献
145.
This study concerns the development and validation of a complete method for the analysis of two highly reactive α-dicarbonyl
compounds, glyoxal (Gly) and methylglyoxal (Mgly), in atmospheric fine particulate matter (PM2.5). Method development included optimization of sample preparation procedures, e.g., filter extraction, concentration of extracts,
derivatization and solid-phase extraction (SPE) of derivatives, as well as reversed-phase liquid chromatography coupled to
electrospray ion-trap mass spectrometry (HPLC-ESI-IT/MS/MS) measurement parameters. Selectivity of detection was enhanced
using tandem mass spectrometric analysis in ESI positive ion mode via two multiple reaction monitoring channels, m/z 433 → m/z 250 and m/z 419 → m/z 236 for Mgly and Gly. Retention times were 9.5 and 12.5 min for Gly- and Mgly-bis-hydrazone derivatives. Calibration ranged
from 0.5 to 50 ng/mL. Inter-batch precision, expressed as relative standard deviation, was <15%. The method was shown to be
unaffected by the sample matrix and to have recoveries of 100% and 60% for Gly and Mgly, respectively. Improved instrumental
detection limits of 0.51 and 0.62 ng/mL for Gly and Mgly were achieved using a SPE method for the purification of 2,4-dinitrophenylhydrazine
derivatization reagent solutions. This permitted the method to be used for analysis of filter samples obtained during a field
study at the Taunus Observatory (mount Kleiner Feldberg, Germany). PM2.5 concentrations ranged from 0.81 to 1.18 ng/m3 for Gly and from 0.83 to 1.92 ng/m3 for Mgly. PM concentrations correlated to the concentration of NO with coefficients (R
2) of 0.67 (Gly) and 0.78 (Mgly). 相似文献
146.
147.
Antina Ghosh Romain Mari V.K. Chikkadi Peter Schall A.C. Maggs Daniel Bonn 《Physica A》2011,390(18-19):3061-3068
We study the vibrational spectrum and the low-energy modes of a three-dimensional colloidal crystal using confocal microscopy. This is done in a two-dimensional cut through a three-dimensional crystal. We find that the observed density of states is incompatible with the standard Debye form in either two or three dimensions. These results are confirmed by numerical simulations. We show that an effective theory for the projections of the modes onto the two-dimensional cut describes the experimental and simulation data in a satisfactory way. 相似文献
148.
This study describes a highly efficient method for the selective precipitation of phosphoproteins by trivalent europium, terbium,
and erbium metal ions. These metal cations belong to the group of lanthanides and are known to be hard acceptors with an overwhelming
preference for oxygen-containing anions such as phosphates to which they form very tight ionic bonds. The method could be
successfully applied to specifically precipitate phosphoproteins from complex samples including milk and egg white by forming
solid metal–protein complexes. Owing to the low solubility product of the investigated lanthanide salts, the produced metal–protein
complexes showed high stability. The protein pellets were extensively washed to remove nonphosphorylated proteins and contaminants.
For the analysis of proteins the pellets were first dissolved in 30 % formic acid and subjected to matrix-assisted laser desorption/ionization–time
of flight (MALDI-TOF) MS. For peptide mass-fingerprint analysis the precipitated phosphoproteins were enzymatically digested
using microwave-assisted digestion. The method was found to be highly specific for the isolation and purification of phosphoproteins.
Protein quantification was performed by colorimetric detection of total precipitated phosphoproteins and revealed more than
95 % protein recovery for each lanthanide salt. 相似文献
149.
V. A. Huck-Pezzei J. D. Pallua C. Pezzei L. K. Bittner S. A. Sch?nbichler G. Abel M. Popp G. K. Bonn C. W. Huck 《Analytical and bioanalytical chemistry》2012,404(6-7):1771-1778
In the present study, Fourier transform infrared (FTIR) imaging and data analysis methods were combined to study morphological and molecular patterns of St. John's wort (Hypericum perforatum) in detail. For interpretation, FTIR imaging results were correlated with histological information gained from light microscopy (LM). Additionally, we tested several evaluation processes and optimized the methodology for use of complex FTIR microscopic images to monitor molecular patterns. It is demonstrated that the combination of the used spectroscopic method with LM enables a more distinct picture, concerning morphology and distribution of active ingredients, to be gained. We were able to obtain high-quality FTIR microscopic imaging results and to distinguish different tissue types with their chemical ingredients. 相似文献
150.
Lukas Trojer Clemens P. Bisjak Wolfgang Wieder Guenther K. Bonn 《Journal of chromatography. A》2009,1216(35):6303-6309
A method for controlling the mesoporous structure of monolithic organic copolymers is presented by systematic variation in polymerisation time, employing poly(p-methylstyrene-co-1,2-(p-vinylphenyl)ethane) (MS/BVPE) as a representative styrene system. Decreasing the time of polymerisation introduces a considerable fraction of mesopores (up to 20% of the total pore volume), while keeping the support permeability reasonable high (~1.3 × 10?14 m2). Monolith structures, prepared in such a manner, enable efficient (typically around 70,000 plates/m) and fast separation of low-molecular-weight compounds, whereas their performance towards biopolymers is comparable to column supports, fabricated according to typically used protocols (polymerisation time >12 h and thus monomer conversion >98%). The polymerisation time is hence a valuable tool to tailor the fraction of support flow-channels, macropores as well as mesopores, which is shown dramatically to influence the chromatographic separation characteristics of the respective column. This way, the preferred applicability of organic (styrene) monolithic copolymers can be extended to the separation of small molecules beyond biopolymer chromatography. 相似文献