全文获取类型
收费全文 | 7503篇 |
免费 | 1310篇 |
国内免费 | 1190篇 |
专业分类
化学 | 6085篇 |
晶体学 | 81篇 |
力学 | 391篇 |
综合类 | 83篇 |
数学 | 786篇 |
物理学 | 2577篇 |
出版年
2024年 | 30篇 |
2023年 | 150篇 |
2022年 | 324篇 |
2021年 | 331篇 |
2020年 | 359篇 |
2019年 | 411篇 |
2018年 | 306篇 |
2017年 | 286篇 |
2016年 | 403篇 |
2015年 | 417篇 |
2014年 | 459篇 |
2013年 | 586篇 |
2012年 | 710篇 |
2011年 | 668篇 |
2010年 | 415篇 |
2009年 | 426篇 |
2008年 | 458篇 |
2007年 | 368篇 |
2006年 | 360篇 |
2005年 | 321篇 |
2004年 | 276篇 |
2003年 | 242篇 |
2002年 | 326篇 |
2001年 | 267篇 |
2000年 | 167篇 |
1999年 | 150篇 |
1998年 | 128篇 |
1997年 | 74篇 |
1996年 | 83篇 |
1995年 | 63篇 |
1994年 | 64篇 |
1993年 | 51篇 |
1992年 | 77篇 |
1991年 | 49篇 |
1990年 | 50篇 |
1989年 | 30篇 |
1988年 | 22篇 |
1987年 | 24篇 |
1986年 | 24篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1971年 | 1篇 |
1959年 | 2篇 |
1957年 | 2篇 |
1936年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
由于纳米材料具有独特的物理和化学性能,使其在许多领域被广泛应用。纳米材料使用的日益增多要求我们仔细评估其难以预料的毒性(细胞毒性、溶血毒性、血液毒性和免疫毒性)和生物学相互作用。到目前为止,已有大量的研究旨在探索纳米材料与人的细胞或蛋白之间的相互作用,也取得了一些重要成果。在临床应用中,有些生物医用纳米材料常通过静脉注射、渗透、溶解和扩散等方式引入到血液组织中。血液是一种高度复杂的组织,主要由红细胞、白细胞、血小板和血浆组成。其中血浆是一个复杂的体液,它包含超过3700种不同的蛋白质。无论采用哪种方式,这些纳米材料将不可避免地会与丰富的血浆蛋白(或其他血液成分)发生某种联系和相互作用。然而,纳米材料和血浆蛋白之间的相互作用,可能在决定纳米材料的毒性方面起到至关重要的作用。目前对纳米材料与血浆蛋白(或其他血液成分)在分子水平会发生怎样的相互作用知之甚少。本文主要综述了典型的三类高分子纳米材料(包括聚阳离子,高分子胶束和药物(基因)/载体复合纳米粒子)与血浆蛋白的相互作用以及研究这些相互作用相关的分析技术的研究进展,这些内容对体内使用的纳米材料的分子设计和血液安全性非常重要。 相似文献
952.
953.
Ruifang Yang Nanjing Zhao Xue Xiao Shaohui Yu Jianguo Liu Wenqing Liu 《Journal of Chemometrics》2015,29(8):442-447
Sparse non‐negative matrix factorization on right side factor (SNMF/R) has better performance in feature extraction than non‐negative matrix factorization. In this work, SNMF/R was first used to separate the overlapped three‐dimensional fluorescence spectra of polycyclic aromatic hydrocarbons mixtures in pure water, lake water, and river water, respectively. It is found that the similarity coefficients between the acquired three‐dimensional spectra and the corresponding reference spectra with random initials are all above 0.80; the recognition rate of SNMF/R is higher than that of PARAFAC and non‐negative matrix factorization algorithms, especially in the case of lake water and river water samples. In addition, SNMF/R does not need any initialization scheme designing during spectra separation. These results demonstrate that SNMF/R is an appropriate algorithm to separate the overlapped fluorescence spectra of polycyclic aromatic hydrocarbons in aquatic environment accurately and effectively. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
954.
Xue Liu Wenbi Guan Xianghong Hao Xiaoli Wu Yongqiang Ma Canping Pan 《Chromatographia》2014,77(1-2):31-37
Graphene is a novel class of carbon nanostructures with ultrahigh specific surface area. Graphene has already been used in many fields and has great promise for use in sorbent materials. In this study, we used graphene mixed with primary secondary amine (PSA) and graphitized carbon black (GCB) as dispersive solid-phase extraction materials for the cleanup of tea for the first time. Compared to the literature, the amount of PSA and GCB was greatly reduced. A multi-residue method combined with liquid chromatography–tandem mass spectrometry was validated for rapid determination of 25 pesticide residues in tea. Green tea, black tea, and white tea were selected as matrixes, representing the majority of tea types. Recoveries ranged from 71.1 to 108.3 % and consistent relative standard deviations <13.6 % for all 25 pesticides. Graphene has significant potential as a promising new adsorbent for pesticide residue analysis of teas. This method can be used to analyze tea samples with different degrees of fermentation. 相似文献
955.
956.
Zhi-Xiang Han Bo-Song Zhu Tong-Liang Wua Qing-Qing Yang Yong-Lai Xue Zhen Zhang Xiang-Yang Wua 《中国化学快报》2014,25(1):73-76
In this paper, 2-carboxybenzaldehyde rhodamine B thiohydrazine(1) was synthesized and developed as a fluorescent probe to recognize Hg2+in DMF/H2 O(1:9, v/v) solution with high selectivity. The probe can be applied to the quanti?cation of Hg2+with a linear concentration range covering from 1.0×10-7mol/L to 1.0×10-5mol/L(R2= 0.9985) and a detection limit of 4.2×10-8mol/L. The experiment results show that the response of probe 1 to Hg2+is pH-independent in a wide range from 4.0 to 9.0. Moreover, the probe 1 exhibits excellent selectivity toward Hg2+over other common metal cations. Most importantly, the probe can be employed to monitor Hg2+in living cells using fluorescent imaging technique with satisfied results. 相似文献
957.
The decay dynamics of N,N-dimethylthioacetamide after excitation to the S3(ππ*) state was studied by using the resonance Raman spectroscopy and complete active space selfconsistent field method calculations. The UV-absorption and vibrational spectra were assigned. The A-band resonance Raman spectra were obtained in acetonitrile, methanol and water with the laser excitation wavelengths in resonance with the first intense absorption band to probe the Franck-Condon region structural dynamics. The CASSCF calculations were carried out to determine the excitation energies and optimized structures of the lowerlying singlet states and conical intersection point. The A-band structural dynamics and the corresponding decay mechanism were obtained by the analysis of the resonance Raman intensity pattern and the CASSCF calculated structural parameters. The major decay channel of 3,FC(ππ*)→S3(ππ*)/S1(nπ*)→1(nπ*) is proposed. 相似文献
958.
Back Cover: Room‐Temperature Synthesis of Cu2−xE (E=S,Se) Nanotubes with Hierarchical Architecture as High‐Performance Counter Electrodes of Quantum‐Dot‐Sensitized Solar Cells (Chem. Eur. J. 3/2015) 下载免费PDF全文
959.
Back Cover: Controllable Galvanic Synthesis of Triangular Ag–Pd Alloy Nanoframes for Efficient Electrocatalytic Methanol Oxidation (Chem. Eur. J. 24/2015) 下载免费PDF全文
960.
Light‐Driven Reversible Alignment Switching of Liquid Crystals Enabled by Azo Thiol Grafted Gold Nanoparticles 下载免费PDF全文
Dr. Chenming Xue Jie Xiang Hossein Nemati Dr. Hari Krishna Bisoyi Karla Gutierrez‐Cuevas Dr. Ling Wang Dr. Min Gao Shuang Zhou Prof. Deng‐ke Yang Prof. Oleg D. Lavrentovich Dr. Augustine Urbas Prof. Quan Li 《Chemphyschem》2015,16(9):1852-1856
Stimuli‐directed alignment control of liquid crystals (LCs) with desired molecular orientation is currently in the limelight for the development of smart functional materials and devices. Here, photoresponsive azo thiol (AzoSH) was grafted onto gold nanoparticles (GNPs). The resulting hybrid GNPs were able to homogeneously mix with a commercially available nematic LC host, as evidenced by Cryo‐TEM. Interestingly, the LC nanocomposites were found to undergo reversible alignment transition upon light irradiation as a consequence of the trans–cis photoisomerization of the azo groups on the GNP surface. LC molecules in either planar or bare glass cells were able to change their alignment to vertical upon UV irradiation, while the vertically aligned LC molecules returned to the planar or random orientation under visible irradiation. Neither the azo thiol molecules nor the unfunctionalized GNPs alone promoted the alignment of the LC molecules in the system upon light irradiation. The photoinduced vertical alignment without applied electric or magnetic field was very stable over time and with respect to temperature. Furthermore, an optically switchable device based on the photostimulated reversible alignment control of LCs was demonstrated. 相似文献