全文获取类型
收费全文 | 1061篇 |
免费 | 42篇 |
国内免费 | 1篇 |
专业分类
化学 | 663篇 |
晶体学 | 3篇 |
力学 | 47篇 |
数学 | 89篇 |
物理学 | 302篇 |
出版年
2023年 | 21篇 |
2022年 | 30篇 |
2021年 | 20篇 |
2020年 | 32篇 |
2019年 | 35篇 |
2018年 | 39篇 |
2017年 | 23篇 |
2016年 | 43篇 |
2015年 | 31篇 |
2014年 | 39篇 |
2013年 | 97篇 |
2012年 | 86篇 |
2011年 | 89篇 |
2010年 | 55篇 |
2009年 | 43篇 |
2008年 | 61篇 |
2007年 | 60篇 |
2006年 | 40篇 |
2005年 | 41篇 |
2004年 | 23篇 |
2003年 | 19篇 |
2002年 | 16篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1939年 | 1篇 |
排序方式: 共有1104条查询结果,搜索用时 15 毫秒
1.
Das Pritam Kumar Mallik Arnab Kumar Molla Altaf Hossain Santra Apurba Kumar Ganguly Ranjan Saha Abhijit Kumar Sugam Aswal V. K. 《Journal of Thermal Analysis and Calorimetry》2022,147(10):5617-5635
Journal of Thermal Analysis and Calorimetry - Nanofluids have gained recent attention because of their potential applications in diverse engineering fields like enhancing thermal transport,... 相似文献
2.
Xiao Huang Bishwa Ranjan Nayak Tao Lu Lowe 《Journal of polymer science. Part A, Polymer chemistry》2004,42(20):5054-5066
A series of novel multifunctional hydrogels that combined the merits of both thermoresponsive and biodegradable polymeric materials were designed, synthesized, and characterized. The hydrogels were copolymeric networks composed of N‐isopropylacrylamide (NIPAAM) as a thermoresponsive component, poly(L‐lactic acid) (PLLA) as a hydrolytically degradable and hydrophobic component, and dextran as an enzymatically degradable and hydrophilic component. The chemical structures of the hydrogels were characterized by an attenuated total reflection–Fourier transform infrared spectroscopy (ATR–FTIR) technique. The hydrogels were thermoresponsive, showing a lower critical solution temperature (LCST) at approximately 32 °C, and their swelling properties strongly depended on temperature changes, the balance of the hydrophilic/hydrophobic components, and the degradation of the PLLA component. The degradation of the hydrogels caused by hydrolytic cleavage of ester bonds in the PLLA component was faster at 25 °C below the LCST than at 37 °C above the LCST, determined by the ATR–FTIR technique. Due to their multifunctional properties, the designed hydrogels show great potential for biomedical applications, including drug delivery and tissue engineering. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5054–5066, 2004 相似文献
3.
Some bounds on the entries and on the norm of the inverse of triangular matrices with nonnegative and monotone entries are found. All the results are obtained by exploiting the properties of the fundamental matrix of the recurrence relation which generates the sequence of the entries of the inverse matrix. One of the results generalizes a theorem contained in a recent article of one of the authors about Toeplitz matrices. 相似文献
4.
Paital AR Mitra T Ray D Wong WT Ribas-Ariño J Novoa JJ Ribas J Aromí G 《Chemical communications (Cambridge, England)》2005,(41):5172-5174
Based on a combined theoretical-experimental study, we propose that substituted m-phenylene ligands (m-N-Phi-N) can act as tuneable strong ferromagnetic couplers connecting Cu(II) ions; a new complex presenting that bridge with J close to +15 cm(-1) has been suggested and synthesized. 相似文献
5.
Rajani K. Samal R. R. Das M. C. Nayak G. V. Suryanarayana G. Panda D. P. Das 《Journal of polymer science. Part A, Polymer chemistry》1981,19(11):2751-2758
The kinetics of polymerization of acrylonitrile initiated by KHSO5 and catalyzed by Ag(I) have been investigated in an aqueous medium over the temperature range of 35–50°C. The rates of polymerization Rp have been calculated and studied with respect to monomer and initiator. The catalytic activity of various metal ions on the initiator has been determined from a comparison of Rp values. The effects of monomer, catalyst, neutral salts, various amines, and inhibitor (hydroquinone) on the initial rate as well as maximum conversion have been studied. From the kinetics results a suitable reaction scheme has been proposed. 相似文献
6.
Upendra Nath Dash Banka Behari Das Uttam Kumar Biswal Tapodhan Panda 《Thermochimica Acta》1984,80(2):331-342
The standard potentials of silver—silver bromide and silver—silver iodide electrodes in glycerol+water mixtures containing 5, 10, 20 and 30 wt% glycerol were determined from electromotive force measurements of the cell Ag(s), AgX(s), KX(c)//KCl(c), AgCl(s), Ag(s), where X is Br or I, at seven different temperatures in the range 5–35°C. The standard potentials in each solvent are represented as a function of temperature. The standard thermodynamic functions for the electrode reactions, the primary medium effects of various solvents upon X−, and the standard thermodynamic quantities for the transfer of 1 g-ion of X− from water to the respective glycerol + water media are evaluated and discussed in the light of ion—solvent interactions as well as the structural changes of the solvents. From the values of the Ag/Ag+ and Ag/AgX, X− electrodes, the thermodynamic solubility product constants of silver chloride, silver bromide and silver iodide have been determined in glycerol + water solvent mixtures at different temperatures. 相似文献
7.
We present exact explicit expressions for the row spin-spin correlation functions
00
n0 in the isotropicd= 2 Ising model, in terms of elliptic integrals, forn 5. We also give a general structural formula for
00
n0. 相似文献
8.
The cis-decalin based gamma-amino alcohols, 1-5, were synthesized, resolved, and employed as catalysts in the addition of organozincs to benzaldehyde. Despite large facial differentiation in the RZn adducts of the ligands, the enantioselectivities were found to be moderate. Transition structure calculations were done using several quantum chemical methods to examine the underlying causes of the selectivity for three gamma-amino alcohols, 1, 2, and 3. The tricyclic mu-oxo (6/4/4), rather than the bicyclic six-membered (6/6), transition structures were found to explain the observed enantioselectivity for 2 and 3. MP2 calculations gave the best correlation to the experimental results compared to B3LYP and HF calculations. The conformational flexibility of the chiral ligands was found to be an important factor in the selectivity. 相似文献
9.
Zulys A Panda TK Gamer MT Roesky PW 《Chemical communications (Cambridge, England)》2004,(22):2584-2585
The cyclooctatetraene-bis(phosphinimino)methanide complex [[CH(PPh2NSiMe3)2]Sm(eta8-C8H8)] has been prepared; although this compound has no alkyl or amide ligand it shows moderate activity as a catalyst for the hydroamination/cyclisation reaction. 相似文献
10.
Photoaffinity labeled (3-diazoacetoxy)-9-cis-retinal (1) and (9-methylenediazoacetoxy)-9-cis-retinal (20) were synthesized and bound to absorption maxima at 465 and 460 nm respectively. Binding studies established that synthetic retinals 1 and 2 bind to the natural binding site and that the integrity of the diazoacetoxy photoaffinity label is preserved in the process. Incorporation of 3-(O14COCHN2)-labeled 9-cis retinal could be conveniently carried out in high yield using apomembrane solubilized in CHAPS as detergent to afford the pigment analog in a pure form. Photolysis of the diazoacetoxy group within the binding site led to 15–20%, crosslinking of rhodopsin as estimated by using radiocarbon containing labeled retinal 1 thus showing that this synthetic retinal is suitable for photoaffinity labeling of the active site in rhodopsin. Subsequent experiments to establish the site(s) of crosslinking by sequencing studies will then contribute to our knowledge of the structure of rhodopsin. 相似文献