全文获取类型
收费全文 | 1225篇 |
免费 | 53篇 |
专业分类
化学 | 945篇 |
晶体学 | 6篇 |
力学 | 23篇 |
数学 | 139篇 |
物理学 | 165篇 |
出版年
2023年 | 15篇 |
2022年 | 57篇 |
2021年 | 57篇 |
2020年 | 40篇 |
2019年 | 43篇 |
2018年 | 21篇 |
2017年 | 35篇 |
2016年 | 62篇 |
2015年 | 45篇 |
2014年 | 44篇 |
2013年 | 93篇 |
2012年 | 103篇 |
2011年 | 103篇 |
2010年 | 47篇 |
2009年 | 46篇 |
2008年 | 65篇 |
2007年 | 67篇 |
2006年 | 46篇 |
2005年 | 46篇 |
2004年 | 33篇 |
2003年 | 31篇 |
2002年 | 29篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 4篇 |
1998年 | 12篇 |
1997年 | 3篇 |
1996年 | 17篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有1278条查询结果,搜索用时 15 毫秒
101.
Trusch M Ehlert S Bertsch A Kohlbacher O Hildebrand D Schlüter H Tallarek U 《Journal of separation science》2010,33(21):3283-3291
The influence of packing process parameters (packing pressure, application of ultrasound) and the stationary phase particle size (3.5 and 5 μm) on the chromatographic performance of HPLC/MS chips was systematically investigated for proteomic samples. First, reproducibility and detection limits of the separation were evaluated with a low‐complexity sample of tryptic BSA peptides. The influence of adsorbent packing quality on protein identification was then tested with a typical proteomics sample of high complexity, a human plasma protein fraction (Cohn fraction IV‐4). All HPLC/MS chips provided highly reproducible separations of these proteomic samples, but improved packing conditions and smaller particle sizes resulted in chromatograms with narrower peaks and correspondingly higher signal intensities. Improved separation performance increased the peak capacity, the number of identified peptides, and thus the sequence coverage in the proteomic samples, particularly for low sample amounts. 相似文献
102.
Donatella Diana Dr. Barbara Ziaco Dr. Guido Scarabelli Dr. Carlo Pedone Prof. Giorgio Colombo Dr. Luca D. D'Andrea Dr. Roberto Fattorusso Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(18):5400-5407
The analysis of the folding mechanism in peptides adopting well‐defined secondary structure is fundamental to understand protein folding. Herein, we describe the thermal unfolding of a 15‐mer vascular endothelial growth factor mimicking α‐helical peptide (QKL10A) through the combination of spectroscopic and computational analyses. In particular, on the basis of the temperature dependencies of QKL10A Hα chemical shifts we show that the first phase of the thermal helix unfolding, ending at around 320 K, involves mainly the terminal regions. A second phase of the transition, ending at around 333 K, comprises the central helical region of the peptide. The determination of high‐resolution QKL10A conformational preferences in water at 313 K allowed us to identify, at atomic resolution, one intermediate of the folding–unfolding pathway. Molecular dynamics simulations corroborate experimental observations detecting a stable central helical turn, which represents the most probable site for the helix nucleation in the folding direction. The data presented herein allows us to draw a folding–unfolding picture for the small peptide QKL10A compatible with the nucleation–propagation model. This study, besides contributing to the basic field of peptide helix folding, is useful to gain an insight into the design of stable helical peptides, which could find applications as molecular scaffolds to target protein–protein interactions. 相似文献
103.
Robert Ahrends Björn Lichtner Andreas Bertsch Oliver Kohlbacher Diana Hildebrand Maria Trusch Hartmut Schlüter 《Journal of chromatography. A》2010,1217(19):3321-3329
It was the aim of this study to compare the performance of displacement chromatography with gradient elution chromatography both applied as the cation-exchange separation step for a proteome analysis in a bottom-up approach using multidimensional chromatography for the separation of tryptic peptides prior to their mass spectrometric analysis. The tryptic digest of the human Cohn fraction IV-4 served as a sample. For both chromatography modes commonly used operating parameters were chosen thus ensuring optimal separation results of equal sample amounts for each mode. All resulting fractions were analyzed with an HPLC-chip–LC–MS system. The eluate of the HPLC-chip column was ionized by electrospray ionization (ESI) and analyzed with an ion-trap mass spectrometer. For guaranteeing high confidence concerning the identity of the peptides, the mass spectrometric data were processed by different bioinformatic tools applying stringent criteria. By the displacement approach the total amount of identified proteins (78) was significantly higher than in the gradient mode (58). The results showed that displacement chromatography is a well suited alternative in comparison to gradient elution separation for analysis of proteomes via the bottom-up approach applying multidimensional chromatography, especially in those cases when larger quantities of proteins are available. 相似文献
104.
Great reductions in the overall size and complexity of high throughput multichannel UV-visible fluorometers were achieved by coupling a compact optical fiber array to compact dispersive transmission optics. The coaxial configuration centers on the insertion of a silica/silica optical fiber into the hollow region of a UV-fused silica capillary waveguide. The outer core delivers the maximum power of the narrow wavelength region of the excitation spectrum created by coupling a xenon arc discharge lamp to a compact spectrometer. The molecular fluorescence resulting from the interaction of light emitted at the distal end of the hollow waveguide and the sample matrix is received and transmitted to a CCD via a compact dispersive grating-prism (grism) optical assembly. A linear array of the coaxial optical fibers permits a full excitation-emission matrix spectrum of the analyte matrix to be projected onto the face of the CCD. The in situ identification and monitoring of polycyclic aromatic hydrocarbons was carried out for the initial application testing for this prototype. 相似文献
105.
Konstantin E. Starkov Diana Gamboa 《Mathematical Methods in the Applied Sciences》2014,37(18):2854-2863
In this paper, we study some features of global behavior of the four‐dimensional superficial bladder cancer model with Bacillus Calmette‐Guérin (BCG) immunotherapy described by Bunimovich‐Mendrazitsky et al. in 2007 with the help of localization analysis of its compact invariant sets. Its dynamics is defined by the BCG treatment and by densities of three cells populations: effector cells, tumor infected cells by BCG, and tumor uninfected cells. We find upper bounds for ultimate dynamics of the whole state vector in the positive orthant and also under condition that there are no uninfected tumor cells. Further, we prove the existence of the bounded positively invariant domain in both of these two situations. Finally, by using these assertions, we derive our main result: sufficient conditions of global asymptotic stability of the tumor‐free equilibrium point in the positive orthant. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
106.
107.
108.
Diana Caponetti Espedito De Pascale Petr P. Zabreįko 《Rendiconti del Circolo Matematico di Palermo》2000,49(3):545-560
Nondifferentiable operator equations in spaces equipped with aK-norm — map taking values in the cone of an ordered Banach space — are studied. The majorant method is used to derive the
convergence of a modified sequence of Newton-Kantorovich approximations. 相似文献
109.
In this paper a family of constacyclic ternary quasi-perfect linear block codes is presented. This family extends the result presented in a previous work by the first two authors, where the existence of codes with the presented parameters was stated as an open question. The codes have a minimum distance 5 and covering radius 3. 相似文献
110.
We describe Steiner loops of nilpotency class 2 and establish the classification of finite 3-generated nilpotent Steiner loops of nilpotency class 2. 相似文献