全文获取类型
收费全文 | 3692篇 |
免费 | 145篇 |
国内免费 | 5篇 |
专业分类
化学 | 2992篇 |
晶体学 | 19篇 |
力学 | 44篇 |
数学 | 399篇 |
物理学 | 388篇 |
出版年
2024年 | 6篇 |
2023年 | 42篇 |
2022年 | 134篇 |
2021年 | 137篇 |
2020年 | 98篇 |
2019年 | 96篇 |
2018年 | 48篇 |
2017年 | 63篇 |
2016年 | 137篇 |
2015年 | 132篇 |
2014年 | 134篇 |
2013年 | 241篇 |
2012年 | 273篇 |
2011年 | 299篇 |
2010年 | 162篇 |
2009年 | 153篇 |
2008年 | 256篇 |
2007年 | 261篇 |
2006年 | 200篇 |
2005年 | 193篇 |
2004年 | 136篇 |
2003年 | 132篇 |
2002年 | 95篇 |
2001年 | 29篇 |
2000年 | 43篇 |
1999年 | 23篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 33篇 |
1995年 | 19篇 |
1994年 | 15篇 |
1993年 | 18篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 16篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1972年 | 3篇 |
排序方式: 共有3842条查询结果,搜索用时 15 毫秒
1.
Biodistribution study of free and microencapsulated 6‐methylcoumarin in Wistar rats by HPLC 下载免费PDF全文
Aura Rocío Hernández Luis Fernando Ospina Diana Marcela Aragón 《Biomedical chromatography : BMC》2015,29(2):176-181
A sensitive, specific and reproducible HPLC method has been developed and validated for the quantitative determination of 6‐methylcoumarin (6MC) in plasma and other tissues in Wistar rats. A C18 column was used with UV detection at 321 nm and a gradient system consisting of methanol‐deionized water was used as mobile phase. The retention time for 6MC was 14.921 min and no interfering peaks were observed for any of the matrices. Linear relationships (r2 > 0.997) were obtained between the peak height ratios and the corresponding biological sample concentrations over the range 0.4–12.8 µg/mL. Precision and accuracy were evaluated; the coefficient of variation and the relative error for all of the organs were <2 and 7%, respectively. The limit of quantitation was 0.20 µg/mL for the heart and 0.30 µg/mL for the other tissues evaluated. This HPLC method was successfully used in the determination of 6MC in the biodistribution study after administration of 200 mg/kg of both 6MC‐free and 6MC‐loaded polymeric microparticles. In this study, extensive 6MC was found, in both free and microencapsulated forms, in all the organs tested. The 6MC‐free showed a range of between 1.7 and 11.5 µg/g, while the microencapsulated 6MC showed concentrations of between 6.35 and 17.7 µg/g, suggesting that 6MC improved absorption rate. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
2.
3.
Functional Binding Surface of a β‐Hairpin VEGF Receptor Targeting Peptide Determined by NMR Spectroscopy in Living Cells 下载免费PDF全文
Dr. Donatella Diana Anna Russomanno Dr. Lucia De Rosa Dr. Rossella Di Stasi Dr. Domenica Capasso Dr. Sonia Di Gaetano Dr. Alessandra Romanelli Dr. Luigi Russo Dr. Luca D. D'Andrea Prof. Roberto Fattorusso 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):91-95
In this study, the functional interaction of HPLW peptide with VEGFR2 (Vascular Endothelial Growth Factor Receptor 2) was determined by using fast 15N‐edited NMR spectroscopic experiments. To this aim, 15N uniformly labelled HPLW has been added to Porcine Aortic Endothelial Cells. The acquisition of isotope‐edited NMR spectroscopic experiments, including 15N relaxation measurements, allowed a precise characterization of the in‐cell HPLW epitope recognized by VEGFR2. 相似文献
4.
5.
6.
7.
Silvia Vogel 《Annals of Operations Research》2006,142(1):269-282
The paper considers upper semicontinuous behavior in distribution of sequences of random closed sets. Semiconvergence in distribution
will be described via convergence in distribution of random variables with values in a suitable topological space. Convergence
statements for suitable functions of random sets are proved and the results are employed to derive stability statements for
random optimization problems where the objective function and the constraint set are approximated simultaneously.
The author is grateful to two anonymous referees for helpful suggestions. 相似文献
8.
Silvia Lorenzo-Freire José M. Alonso-Meijide Balbina Casas-Méndez Ruud Hendrickx 《European Journal of Operational Research》2007
Calleja et al. [Calleja, P., Borm, P., Hendrickx, R., 2005. Multi-issue allocation situations. European Journal of Operational Research 164, 730–747] introduced multi-issue allocation situations with awards. In this paper, we extend the classical model of cooperative games with transferable utility to the cooperative games with transferable utility and awards. We define a run-to-the-bank rule for cooperative games with transferable utility and awards and characterise it in terms of a property of balanced contributions. We apply our main result to bankruptcy problems and multi-issue allocation situations with awards. 相似文献
9.
Electronic structure calculations based on density functional theory were performed for solids and large molecules. The solids were represented by clusters of 60–100 atoms embedded in the potential of the external crystal. Magnetic moments and Mössbauer hyperfine parameters were derived. 相似文献
10.
In this paper we report the results of a morphological and structural investigation on film properties of a soluble polydiacetylene, the poly[1,6-bis(3,6-dihexadecyl-N-carbazolyl)-2,4-hexadiyne] (polyDCHD-HS). The red films of this polymer, prepared by standard spin-coating techniques, revealed absence of linear dichroism and birefringence in contrast with the ordered mesophases detected by powder X-ray studies. In order to interpret the optical behavior of this polymer, we performed AFM and SEM studies of polyDCHD-HS films spun on hydrophylic and hydrophobic glass substrates. We found the presence of surfaces organized in rod-like particles, more regularly oriented on the hydrophylic substrate. GIXRD studies, carried out on films sufficiently thick to allow the observation of the diffraction pattern, reveled the presence of a lamellar structure with a spacing of 3.22 nm. The low intensity of the diffraction peaks and the isotropic linear optical properties of the films show that the lamellar mesophases are not extended over large areas. These findings were compared with the data obtained from AFM and SEM studies on films of two other polydiacetylenes, the poly[1-(3,6-dihexadexyl-N-carbazolyl)-6-(N-carbazolyl)-2,4-hexadyine] (polya-DCHD) and the poly[1,6-bis(3,6-dipalmitoyl-N-carbazolyl)-2,4-hexadyine] (polyDPCHD), spun on hydrophylic glass substrate. The results confirmed the presence of nodular morphologies which seem to be a general characteristic of this class of materials. The particles organization appears instead related to the chemical nature of the substituents on the carbazolyl rings. 相似文献