全文获取类型
收费全文 | 1100篇 |
免费 | 181篇 |
国内免费 | 149篇 |
专业分类
化学 | 843篇 |
晶体学 | 18篇 |
力学 | 70篇 |
数学 | 81篇 |
物理学 | 418篇 |
出版年
2024年 | 3篇 |
2023年 | 25篇 |
2022年 | 45篇 |
2021年 | 57篇 |
2020年 | 45篇 |
2019年 | 55篇 |
2018年 | 33篇 |
2017年 | 39篇 |
2016年 | 55篇 |
2015年 | 64篇 |
2014年 | 73篇 |
2013年 | 81篇 |
2012年 | 103篇 |
2011年 | 121篇 |
2010年 | 63篇 |
2009年 | 66篇 |
2008年 | 54篇 |
2007年 | 55篇 |
2006年 | 60篇 |
2005年 | 41篇 |
2004年 | 48篇 |
2003年 | 31篇 |
2002年 | 26篇 |
2001年 | 13篇 |
2000年 | 22篇 |
1999年 | 28篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 15篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有1430条查询结果,搜索用时 15 毫秒
991.
UNIQUENESS OF VISCOSITY SOLUTIONS OF FULLY NONLINEAR SECOND ORDER PARABOLIC PDE''''S 总被引:1,自引:0,他引:1
This paper investigates the maximum principle for viscosity solutions of fully nonlinear, second order parabolic, possibly degenerate partial differential equations. Using this maximum principle the anthor prove that viscosity solutions of initial and bo unoary value problem for parabolic equations are unique. 相似文献
992.
993.
994.
Ziwen Zhao Lizhong Hu Heqiu Zhang Jingchang Sun Jiming Bian Jianze Zhao 《Applied Surface Science》2011,257(11):5121-5124
Influence of annealing temperature on the properties of Sb-doped ZnO thin films were studied. Hall measurement results indicated that the Sb-doped ZnO annealed at 950 °C was p-type conductivity. X-ray diffraction (XRD) results indicated that the Sb-doped ZnO thin films prepared at the experiments are high c-axis oriented. It was worth noting that p-type sample had the worst crystallinity. The measurements of low-temperature photoluminescence (PL) spectra indicate that the sample annealed at the temperatures of 950 °C showed strong acceptor-bound exciton (A0X) emission, and confirmed that it is related to Sb-doping by comparing with the undoped ZnO low-temperature PL spectrum. 相似文献
995.
考察化学法和电化学法两种方法制备的聚苯胺的电化学活性差别;研究聚苯胺的催化性能及气敏性能。通过有关聚苯胺的系列实验学习,让学生了解导电聚合物的性能及其在化学传感器中的应用及前景。 相似文献
996.
模体是蛋白质二级结构上的一种特征序列,激酶底物通常具有一类特征性的模体,识别底物模体对鉴定激酶底物具有重要意义。为了快速鉴定激酶底物模体,将全细胞蛋白质酶解液作为肽段文库的来源,采用碱性磷酸酶去除肽段的固有磷酸化后构建了用于筛选激酶底物模体的肽段文库。该肽段文库是大量非磷酸化肽段的混合物,将此混合肽段与酪蛋白激酶2和三磷酸腺苷作用30 min后,通过固定化金属离子亲和色谱法富集磷酸化肽段,采用反相液相色谱-串联质谱分析,成功地鉴定到472条非冗余底物肽段,包含451个非冗余磷酸化位点,并由此得到底物模体S/T-D/E-x-D/E。该法能够快速准确地筛选出激酶底物模体,对研究激酶-底物识别以及信号转导过程具有重要意义。 相似文献
997.
The unfolding of bovine heart cytochrome c induced by urea and guanidine hydrochloride was first studied through intrinsic fluorescence emission spectra and fluorescence phase diagram and the results showed that both of them separately followed a two‐state model. As the simplest sample of the unfolding of protein molecules induced by denaturants, an equation was presented to show the effect of the denaturant concentrations in denaturation solution on the residual activity ratios of bovine heart cytochrome c in their two‐state unfolding. There are two characteristic unfolding parameters K and m in this equation. The former is the thermodynamic equilibrium constant of the unfolding of bovine heart cytochrome c induced by denaturants, the latter is the number of denaturant molecules associated with a bovine heart cytochrome c molecule during the unfolding procedure, and through them the distribution and transition of native and completely unfolded bovine heart cytochrome c conformations under different concentrations of urea or guanidine hydrochloride in denaturation solution can be accurately described. 相似文献
998.
Fluorescence spectroscopy, Fourier transform infrared (FT‐IR) spectroscopy, circular dichroism (CD) and FT‐Raman spectroscopy were employed to analyze the binding of the asiatic acid (AA) to bovine serum albumin (BSA) under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by AA was the result of the formation of BSA‐AA complex. The fluorescence quenching mechanism of BSA by AA was a static quenching procedure. According to the Van′t Hoff equation, the thermodynamic parameters enthalpy change (ΔH0) and entropy change (ΔS0) for the reaction were evaluated to be ?12.55 kJ·mol?1 and 67.08 kJ·mol?1, respectively, indicating that hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The influence of AA on the conformation of BSA has also been analyzed on the basis of FT‐IR, CD and FT‐Raman spectra. 相似文献
999.
The unfolding of bovine heart cytochrome c induced by urea and guanidine hydrochloride was studied through their intrinsic fluorescence emission spectra, fluorescence phase diagrams, fluorescence quenching, size‐exclusion chromatographies, native polyacrylamide gel electrophoreses and deactivation profiles. The results showed that during their unfolding in urea and guanidine hydrochloride solutions, bovine heart cytochrome c molecules existed only in a unimolecular form and their bi‐molecular and/or poly‐molecular aggregates and aggregate precipitates were not formed all along. When the urea and guanidine hydrochloride concentrations in denaturation solution were separately about 6.0 and 3.0 mol/L, they could be completely deactivated and almost all of the tryptophan residues originally embedded in the interior of their molecules were exposed to the surface of their molecules. Different from the unfolding of the most often used horse heart cytochrome c, that of bovine heart cytochrome c induced by urea and guanidine hydrochloride was separately a completely co‐operative procedure and followed a two‐state model. 相似文献
1000.
Shin Ichi Kuroda 《中国化学快报》2011,22(12):1505-1508
A series of poly(2-acetoxyethyl methacrylate)/polystyrene(PAEMA/PS) latex interpenetrating polymer networks(LIPNs) were prepared by seeded soap-free emulsion polymerization of styrene on the crosslinked PAEMA seed particles using an oil-soluble initiator.These PAEMA/PS LIPNs showed a well-defined phase-separated structure with PS phase dispersing in continuous PAEMA phase.The domain size of PS phase was found to depend on the crosslinking degree of PAEMA seed particles and the amount of second-stage styrene monomer. 相似文献