全文获取类型
收费全文 | 1931篇 |
免费 | 310篇 |
国内免费 | 169篇 |
专业分类
化学 | 1346篇 |
晶体学 | 25篇 |
力学 | 139篇 |
综合类 | 12篇 |
数学 | 173篇 |
物理学 | 715篇 |
出版年
2024年 | 5篇 |
2023年 | 34篇 |
2022年 | 64篇 |
2021年 | 77篇 |
2020年 | 71篇 |
2019年 | 55篇 |
2018年 | 71篇 |
2017年 | 67篇 |
2016年 | 92篇 |
2015年 | 109篇 |
2014年 | 119篇 |
2013年 | 152篇 |
2012年 | 186篇 |
2011年 | 199篇 |
2010年 | 112篇 |
2009年 | 127篇 |
2008年 | 125篇 |
2007年 | 123篇 |
2006年 | 102篇 |
2005年 | 78篇 |
2004年 | 40篇 |
2003年 | 33篇 |
2002年 | 35篇 |
2001年 | 31篇 |
2000年 | 36篇 |
1999年 | 30篇 |
1998年 | 25篇 |
1997年 | 24篇 |
1996年 | 32篇 |
1995年 | 15篇 |
1994年 | 18篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1991年 | 15篇 |
1990年 | 24篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1981年 | 2篇 |
1976年 | 2篇 |
1957年 | 1篇 |
1942年 | 1篇 |
1941年 | 1篇 |
1936年 | 4篇 |
1930年 | 2篇 |
1929年 | 1篇 |
1927年 | 1篇 |
1923年 | 1篇 |
排序方式: 共有2410条查询结果,搜索用时 265 毫秒
161.
Background
The microtubule associated protein tau is the principle component of neurofibrillar tangles, which are a characteristic marker in the pathology of Alzheimer's disease; similar lesions are also observed after chronic alcohol abuse. Formaldehyde is a common environmental contaminant and also a metabolite of methanol. Although many studies have been done on methanol and formaldehyde intoxication, none of these address the contribution of protein misfolding to the pathological mechanism, in particular the effect of formaldehyde on protein conformation and polymerization. 相似文献162.
Qiuhua Nie Tiefeng Xu Xiang Shen Xudong Zhang 《Journal of Physics and Chemistry of Solids》2007,68(4):477-481
A series of Er3+-doped Bi2O3-B2O3-SiO2-Na2O glasses with different hydroxyl groups were prepared and the interaction between the Er3+ ions and OH groups was investigated. Infrared spectra were measured in order to calculate the exact content of OH groups in samples. The observed increase of the fluorescence lifetime with the oxygen bubbling time has been related to the reduction in the OH content concentration evidenced by infrared (IR) absorption spectra, which confirmed that the OH groups were dominant quenching centers of excited Er3+ and a cause of concentration quenching of 1.5 μm band emission. Various nonradiative decay rates from 4I13/2 of Er3+ with the change of OH content were determined from the fluorescence lifetimes and radiative decay rates, which were calculated on the basis of Judd-Ofelt theory. 相似文献
163.
Ryan Guterman Bradley M. Berven T. Chris Corkery Heng‐Yong Nie Mike Idacavage Elizabeth R. Gillies Paul J. Ragogna 《Journal of polymer science. Part A, Polymer chemistry》2013,51(13):2782-2792
An array of highly fluorinated polymerizable phosphonium salts (HFPPS) were synthesized from PH3 and utilized in UV‐curable formulations. Inclusion of these salts at very low loading (0.1–1 wt %) into hexanediol diacrylate (HDDA) resulted in hydrophobic surfaces. The water repellency was achieved with short C4F9 fluorocarbon appendages in the monomer as opposed to the bioaccumulative C8F17 appended polymers. The physical properties of these new monomers were also characterized. The molecular architecture of the monomers had a pronounced effect on both their physical properties along with the degree of hydrophobicity imparted in the polymer. Salts utilizing the bis(trifluoromethylsulfonyl)imide anion displayed excellent compatibility with HDDA, while the chloride salts were insoluble. Time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) confirmed the presence of the HFPPS at the surface of the polymer coating. For the first time this demonstrates how these salts may be used to functionalize the surface of a UV‐cured film with ionic species. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2782–2792 相似文献
164.
Dequan Zhuang Jun Nie Jing Yang 《Journal of polymer science. Part A, Polymer chemistry》2011,49(9):1999-2007
In this work, a strategy for chemical synthesis of ascorbic acid functionalized polyacrylates (PAAA) was accomplished in a two‐step process, first a reversible addition fragmentation chain‐transfer (RAFT) polymerization on a benzyl‐protected ascorbyl acrylate monomer, followed by a deprotection (debenzylation) reaction. The polymers were characterized by 1H NMR, 13C NMR and gel permeation chromatograph. The polymerization ability of redox pair including PAAA and H2O2 were conducted through the measurement of 2‐hydroxyethyl acrylate (HEA) conversion against time via real‐time FT‐NIR. It was found that PAAA in the presence of H2O2, independent on itself chain length, exhibited much faster polymerization than small molecule ascorbic acid (smAA) as reductant at identical condition. Interestingly, when the concentration of ascorbate repeating unit was over some critical value, the polymerization kinetics of HEA could be tunable by simply adjusting the initial molar ratio of reductant to oxidant and environmental pH. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
165.
Hong-Yan Zou Hai-Long Wu Yan Zhang Shu-Fang Li Jin-Fang Nie Hai-Yan Fu Ru-Qin Yu 《Journal of fluorescence》2009,19(6):955-966
In this paper, UV–vis spectroscopy and fluorescence were combined to study the binding of Calf thymus DNA (ct-DNA) with the anthacycline antibiotic drug pirarubicin (THP). Ethidium bromide (EB) as the fluorescence probe was used to study the competitive binding interactions of THP with DNA by excitation -emission fluorescence matrices (EEFMs) coupled with the parallel factor analysis (PARAFAC) and the alternating normalization-weighted error algorithm (ANWE) with the second-order advantage. All the results conformed that THP mainly bound with DNA by intercalation. Meanwhile, the two second-order calibration methods have been successfully applied to quantify THP in urine samples. Figures of merit were applied to compare the performance of the two methods. The results presented in this work showed that both the PARAFAC and ANWE methods were the convincing way to be applied in the complex biological systems even in the presence of uncalibrated interferences. 相似文献
166.
167.
Dongxia Nie Ping Li Dan Zhang Tianshu Zhou Ying Liang Guoyue Shi 《Electrophoresis》2010,31(17):2981-2988
In this article, a carbon disk electrode modified with mesoporous carbon material (CMK‐3) was used in CE with amperometric detection system for the simultaneous determination of four types of important nitroaromatic compounds, including 2,4,6‐trinitrotoluene (TNT), 1,3,5‐trinitrobenzene (TNB), 2,4‐dinitrotoluene (DNT) and 1,3‐dinitrobenzene (DNB). Compared with the bare carbon electrode, the CMK‐3 modified electrode greatly improved the sensitivity at a relatively positive detection potential due to its excellent electrocatalytic activities, high conductivity and large effective surface area. The four analytes could be well separated and detected within 480 s. A good linear response was obtained for TNB, DNB, TNT and DNT from 8.4 to 5.0×103 μg/L, with correlation coefficients higher than 0.9992. And the detection limits were established between 3.0 and 4.7 μg/L for the four investigated nitroaromatic compounds (S/N=3). The CMK‐3‐modified electrode was successfully employed to analyze coking wastewater, tap water and river samples with recoveries in the range of 94.8–109.0%, and RSDs less than 5.0%. The presented results demonstrated that the CMK‐3‐modified carbon electrode used in CE with amperometric detection was of convenient preparation, high sensitivity and good repeatability, which could be employed in the rapid determination of practical samples. 相似文献
168.
A. Janke H. Hiller R. Dworzak L. Ebert C. Mayr E. Kroupa G. Koller F. v. Wessely H. Lieb J. Schintlmeister M. Nießner G. Lock G. Ortner 《Mikrochimica acta》1942,30(1-2):181-192
Ohne Zusammenfassung 相似文献
169.
170.
F. Hecht H. Zellner A. A. Benedetti-Pichler A. Franke F. v. Wessely M. Nießner A. Grünwald G. Koller G. Ortner R. Dworzak E. Baroni 《Mikrochimica acta》1941,29(1-2):134-158
Ohne Zusammenfassung 相似文献