全文获取类型
收费全文 | 202篇 |
免费 | 18篇 |
国内免费 | 32篇 |
专业分类
化学 | 176篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 6篇 |
物理学 | 67篇 |
出版年
2024年 | 3篇 |
2023年 | 7篇 |
2022年 | 21篇 |
2021年 | 22篇 |
2020年 | 17篇 |
2019年 | 18篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 16篇 |
2013年 | 14篇 |
2012年 | 5篇 |
2011年 | 14篇 |
2010年 | 2篇 |
2009年 | 13篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 9篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 3篇 |
1984年 | 1篇 |
排序方式: 共有252条查询结果,搜索用时 15 毫秒
41.
Ekaterina I. Shishatskaya 《Macromolecular Symposia》2008,269(1):65-81
This work is a review of the results of biomedical studies of polymer devices (films, fibers, microparticles, 3D implants) made from resorbable PHAs synthesized by the bacterium Wautersia (Ralstonia) eutropha B5786, using the technology developed at the Institute of Biophysics of the Siberian Branch of the Russian Academy of Sciences. Two types of PHAs – polyhydroxybutyrate (PHB) and a hydroxybutyrate/hydroxyvalerate copolymer (PHB/PHV) – have been proven to be biocompatible in vitro in cultures of fibroblasts, endothelial cells, hepatocytes, and osteoblasts, and in short- and long-duration experiments on animals. Polymer films and membranes have been found to be usable as scaffolds for functioning cells and monofilament suture fibers – for stitching muscular-fascial wounds and in abdominal surgery. Ectopic bone formation assay and experiments with the model of segmental osteotomy showed that 3D PHB and PHB/HA implants can be used for reparative osteogenesis. The paper reports beneficial results of using polymers to repair bone defects in oral surgery. 相似文献
42.
低相干光干涉测量技术作为重要的非接触测量方法之一,由于具有结构简单、测量速度快及分辨率高的优点,在光学系统的非接触测量及生物医学影像等前沿领域具有广阔的应用前景。本文对透镜组的光学元件中心厚度及空气间隔的非接触测量技术进行了总结,简述了基于OCT的生物医学影像方面研究现状,重点论述基于低相干光干涉法测量原理和研究进展,对比分析相关研究方法的优缺点和创新之处,并从系统结构和应用范围的角度对低相干干涉测量技术的发展趋势作了展望。 相似文献
43.
44.
Shape‐memory polymers (SMP) are versatile stimuli‐responsive materials that can switch, upon stimulation, from a temporary to a permanent shape. This advanced functionality makes SMP suitable and promising materials for diverse technological applications, including the fabrication of smart biomedical devices. In this paper, advances in the design of SMP are discussed, with emphasis on materials investigated for medical applications. Future directions necessary to bring SMP closer to their clinical application are also highlighted.
45.
Tao X Liu Y Wang Y Qiu Y Lin J Zhao A Su M Jia W 《Analytical and bioanalytical chemistry》2008,391(8):2881-2889
An optimized method based on GC-MS with ethyl chloroformate derivatization has been developed for the comprehensive analysis
of endogenous metabolites in serum. Twenty-two reference standards and serum samples were used to validate the proposed method.
The correlation coefficient was higher than 0.9900 for each of the standards, and the LOD varied from 125 to 300 pg on-column.
The analytical equipment exhibited good repeatability (RSD<10%) for all of the standards. Both the repeatability and the within-48-h
stability of the analytical method were satisfactory (RSD<10%) for the 18 metabolites identified in the serum samples. Mean
recovery was acceptable for the 18 metabolites, ranging from 70% to 120% with RSDs of less than 10%. Using the optimized protocol
and a subsequent multivariate statistical technique, complete differentiation was achieved between the metabolic profile of
uremic patients and that of age- and sex-matched normal subjects. Significantly decreased levels of valine, leucine, and isoleucine
and increased levels of myristic acid and linoleic acid were observed in the patient group. This work demonstrated that this
method is suitable for serum-based metabolic profiling studies. 相似文献
46.
47.
Wei Xie Le Su Aiguo Shen Arnulf Materny Jiming Hu 《Journal of Raman spectroscopy : JRS》2011,42(6):1248-1254
In surface‐enhanced Raman scattering (SERS), the scattered intensity is drastically increased due to a resonant interaction with surface plasmons of coin metals. SERS is a nondestructive spectroscopic method applied also to biomedical samples. It inherits the advantages of normal Raman spectroscopy and at the same time overcomes the inherent low sensitivity problem. These properties endow SERS with exciting opportunities to be a successful analytical tool for cell analysis. SERS can be used to detect only molecules located on or close to the metallic nanostructures which can support surface plasmon resonances for the enhancement of the Raman signals. Therefore, these metallic nanostructures play a key role in the application of SERS in cell analysis. By incorporating the SERS substrates into the biosamples, molecular structural probing and cellular imaging become possible. In the past decade, analysts worldwide have developed many schemes to study the chemical changes and component distribution in cells by using SERS. In this paper, the application of SERS in cell analysis is reviewed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
48.
Jesús Emmanuel Solís‐Prez Jos Francisco Gmez‐Aguilar Lizeth Torres Ricardo Fabricio Escobar‐Jimnez Juan Reyes‐Reyes 《Mathematical Methods in the Applied Sciences》2019,42(18):7335-7348
In this work, the design of spectral observers for signal reconstruction based on Kalman filters is performed and evaluated. The conformable derivative and the beta‐derivative were used to design the Kalman filters. Both derivatives satisfy the same formulas of the classical derivation, eg, the chain rule. The derivative order, the Ricatti equation parameters, and the observers tuning parameters were optimized using an optimization algorithm based on the bat's echolocation behavior (Bat algorithm). The simulation results showed the advantages of using the proposed observers for the signal reconstruction. 相似文献
49.
Alena A. Nastulyavichus Irina N. Saraeva Andrey A. Rudenko Roman A. Khmelnitskii Alexander L. Shakhmin Demid A. Kirilenko Pavel N. Brunkov Nikolay N. Melnik Nikita A. Smirnov Andrey A. Ionin Sergey I. Kudryashov 《Particle & Particle Systems Characterization》2020,37(5):2000010
Si nanoparticles (NPs), which are innovative promising light-harvesting components of thin-film solar cells and key-enabling biocompatible theranostic elements of infrared-laser and radiofrequency hyperthermia-based therapies of cancer cells in tumors and metastases, are significantly advanced in their near/mid-infrared band-to-band and free-carrier absorption via donor sulfur-hyperdoping during high-throughput facile femtosecond-laser ablative production in liquid carbon disulfide. High-resolution transmission electron microscopy and Raman microscopy reveal their mixed nanocrystalline/amorphous structure, enabling the extraordinary sulfur content of a few atomic percents and very minor surface oxidation/carbonization characterized by energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. A 200-nm thick layer of the nanoparticles exhibits near−mid-infrared absorbance, comparable to that of the initial 380-micron thick n-doped Si wafer (phosphor-dopant concentration ≈1015 cm−3), with the corresponding extinction coefficient for the hyperdoped NPs being 4–7 orders higher over the broadband spectral range of 1–25 micrometers. Such ultimate, but potentially tunable mid-IR structured, multi-band absorption of various sulfur-impurity clusters and smooth free-carrier absorption are break through advances in mid-infrared (mid-IR) laser and radiofrequency (RF) hyperthermia-based therapies, as envisioned in the RF-heating tests, and in fabrication of higher-efficiency thin-film and bulk photovoltaic devices with ultra-broad (UV−mid-IR) spectral response. 相似文献
50.