全文获取类型
收费全文 | 292篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
化学 | 167篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 37篇 |
物理学 | 104篇 |
出版年
2022年 | 12篇 |
2021年 | 9篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 16篇 |
2013年 | 22篇 |
2012年 | 28篇 |
2011年 | 19篇 |
2010年 | 20篇 |
2009年 | 15篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 12篇 |
2005年 | 10篇 |
2003年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1958年 | 1篇 |
1957年 | 3篇 |
1956年 | 1篇 |
排序方式: 共有313条查询结果,搜索用时 203 毫秒
71.
The influence of drying temperature on the properties of latex films was investigated by gravimetry, turbidimetry (i.e., analysis of transmission spectra and interference), atomic force microscopy and measurement of water vapor permeability. Several pitfalls in the determination of water content of dried films that absorb water after being submerged in it have been proposed, such as fading boundaries, remaining water after drying and change of particle sizes. At moderately higher temperatures film formation is improved. This improvement follows from the formation of smoother film surfaces (AFM), lower water vapor permeabilities and smaller values for delta lambda(min). On the other hand, defects as cracks and channels also are created, especially at high temperatures. It appears, however, that these channels do not run from the one surface of a film to the other. 相似文献
72.
The rate constant kir for quenching diaryl ketone triplet states by electron poor olefins in CCl4 at room temperature decreases with decreasing reduction potential of the olefin. Unlike in previous cases, our data here fit the Weller equation, which predicts that en kir ≈ 1/RT. 相似文献
73.
P.K. Singh Shiva Prasad R.M. Mehra Pran Kishan S.B. Singh G.P. Srivastava 《Journal of magnetism and magnetic materials》1980,21(3):297-306
A new technique to determine the effective line width ΔHeff using the dimensional resonance phenomenon observed in magneto-microwave Kerr-effect experiment is discussed. This effect depends on the Permeability tensor components and the damping parameter α. The components of permeability tensor μ have been calculated theoritically and the damping parameter α is determined from experimental data. The measurements have been made at 24 GHz on three samples of lithium ferrite and their effective line widths have been obtained both in the partially magnetised and the saturated states of magnetisation. It has been found that ΔHeff for two states of magnetisation are different. Further, the value of ΔHeff obtained are higher than expected at this frequency. This suggests the possibility of additional relaxation mechanisms at dimensional resonance. 相似文献
74.
Magneto-microwave Kerr effect has been experimentally studied on three ferrite samples in the Polder-Smit loss region. Experimental data have been compared with the theoretical values which were calculated on the basis that the real part of the permeability tensor element μ′ is given by Green and Sandy's expressions (IEEE Trans. Microwave Theory Tech. MTT-22, 641 (1974)). This has a term given by Schlomann for μ′0, the permeability for the demagnetised state. No agreement is found between theoretical and experimental values hence the above expression for ν′0 has been substituted by another one given by Sandy (Raytheon Tech. Memor. T-815 (1969)) which involves the average demagnetisation factor N. It is found that there is a good agreement between the theory and the experiment provided N is assumed to depend linearly on the magnetisation of the sample. 相似文献
75.
Shiva P. Singh Surendra S. Parmar Sylvia A. Farnum Virgil I. Stenberg 《Journal of heterocyclic chemistry》1978,15(7):1083-1087
The natural abundance carbon-13 nuclear magnetic resonance spectra of diazepam, clonazepam, flurazepam and chlordiazepoxide were recorded in suitable solvent using the Fourier transform technique on a JEOL FX-60 spectrometer. The relaxation time (T1) of these compounds were also measured. The chemical shift of the various carbon resonances have been assigned on the basis of chemical shift theory, multiplicity generated in single-frequency off-resonance decoupled spectra, relaxation time and the chemical shifts of the model compounds. 相似文献
76.
Shiva Prasad 《Journal of magnetism and magnetic materials》1977,5(4):353-355
A study of the magneto-microwave Kerr effect on two samples of ferrites lying in the Polder-Smit region gives a negative value of μ', the real part of the transverse diagonal term of permeability tensor. There is a negative peak for μ' at a d.c. magnetization approximately equal to of the saturation magnetization. 相似文献
77.
78.
1H NMR‐based metabolomics exploring urinary biomarkers correlated with proteinuria in focal segmental glomerulosclerosis: a pilot study
下载免费PDF全文
![点击此处可从《Magnetic resonance in chemistry : MRC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Shiva Kalantari Mohsen Nafar Shiva Samavat Mahmoud Parvin B. Fatemeh Nobakht M.GH. Farnaz Barzi 《Magnetic resonance in chemistry : MRC》2016,54(10):821-826
Focal segmental glomerulosclerosis (FSGS) is a common glomerulonephritis, and its rates of occurrence are increasing worldwide. Proteinuria is a clinical defining feature of FSGS which correlates with the severity of podocyte injury in patients with nephrotic‐range protein excretion. Metabolite biomarkers corresponding with the level of proteinuria could be considered as non‐invasive complementary prognostic factors to proteinuria. The urine samples of 15 patients (n = 6 women and n = 9 men) with biopsy‐proven FSGS were collected and subjected to nuclear magnetic resonance (NMR) analysis for metabolite profiling. Multivariate statistical analyses, including principal component analysis and orthogonal projection to latent structure discriminant analysis, were applied to construct a predictive model based on patients with proteinuria >3000 mg/day and <3000 mg/day. In addition, random forest was performed to predict differential metabolites, and pathway analysis was performed to find the defective pathways responsible for proteinuria. Ten metabolites, significant in both statistical methods (orthogonal projection to latent structure discriminant analysis and random forest), were considered as prognostic biomarkers for FSGS: citrulline, dimethylamine, proline, acetoacetate, alpha‐ketoisovaleric acid, valine, isobutyrate, D‐Palmitylcarnitine, histidine, and N‐methylnicotinamide. Pathway analysis revealed impairment of the branched‐chain amino acid degradation pathways in patients with massive proteinuria. This study shows that metabolomics can reveal the molecular changes corresponding with disease progression in patients with FSGS and provide a new insight for pathogenic pathways. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
79.
David Remillard Dr. Dennis L. Buckley Dr. Joshiawa Paulk Dr. Gerard L. Brien Matthew Sonnett Dr. Hyuk-Soo Seo Shiva Dastjerdi Dr. Martin Wühr Dr. Sirano Dhe-Paganon Dr. Scott A. Armstrong Dr. James E. Bradner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5832-5837
The bromodomain-containing protein BRD9, a subunit of the human BAF (SWI/SNF) nucleosome remodeling complex, has emerged as an attractive therapeutic target in cancer. Despite the development of chemical probes targeting the BRD9 bromodomain, there is a limited understanding of BRD9 function beyond acetyl-lysine recognition. We have therefore created the first BRD9-directed chemical degraders, through iterative design and testing of heterobifunctional ligands that bridge the BRD9 bromodomain and the cereblon E3 ubiquitin ligase complex. Degraders of BRD9 exhibit markedly enhanced potency compared to parental ligands (10- to 100-fold). Parallel study of degraders with divergent BRD9-binding chemotypes in models of acute myeloid leukemia resolves bromodomain polypharmacology in this emerging drug class. Together, these findings reveal the tractability of non-BET bromodomain containing proteins to chemical degradation, and highlight lead compound dBRD9 as a tool for the study of BRD9. 相似文献
80.
Shiva Salem 《Chemical Papers》2016,70(3):356-364
The autoignition technique using glycine as fuel and related nitrate salts as an oxidiser is able to produce zinc aluminate spinel. The precursors were synthesised with lean and rich fuel at pH of 7.0 and the materials so obtained were calcined at various temperatures ranging from 600–1200°C. The autoignition process of precursors was studied by the simultaneous thermo-gravimetric and differential thermal analyses to determine the ignition mechanism. The calcined powders were characterised by X-ray diffraction, Brunauer–Emmett–Teller technique and transmission electron microscopy. The product contains nano-sized particles with an average size of approximately 20 nm. The XRD patterns showed the formation of ZnO in the powder obtained by the fuel-rich precursor and calcined at 600 C which disappears at 800 C due to solid-state reaction and proper crystallisation after heat treatment. The results presented here can be useful in manufacturing nano and micro-sized ZnAl2O4 on an industrial scale using the combustion technique. 相似文献