全文获取类型
收费全文 | 629篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
化学 | 412篇 |
晶体学 | 17篇 |
力学 | 2篇 |
数学 | 53篇 |
物理学 | 166篇 |
出版年
2024年 | 3篇 |
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 18篇 |
2013年 | 53篇 |
2012年 | 55篇 |
2011年 | 37篇 |
2010年 | 21篇 |
2009年 | 20篇 |
2008年 | 33篇 |
2007年 | 22篇 |
2006年 | 29篇 |
2005年 | 25篇 |
2004年 | 23篇 |
2003年 | 23篇 |
2002年 | 16篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1973年 | 4篇 |
1958年 | 4篇 |
1957年 | 4篇 |
排序方式: 共有650条查询结果,搜索用时 15 毫秒
81.
82.
The synthesis and characterization of calcium carbonate microparticles by reaction of calcium chloride and ammonium bicarbonate in the presence of negatively charged phospholipid mixtures of negative and zwitterionic phospholipids has been reported. Negatively charged phospholipids influence the crystal morphology of calcium carbonate and induce the formation of thermodynamically less stable veterite polymorph as opposed to calcite polymorph. The phospholipids are entrapped in the calcium carbonate microparticles during the crystallization process, with a uniform distribution of phospholipids in the interior of the microparticles. This phenomenon was exploited to encapsulate a model hydrophobic fluorophore, the tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) dichloride complex, to simulate encapsulation of hydrophobic drug molecules. Thermogravimetric analysis reveals that, in these microparticles, the calcium carbonate and the phospholipid exhibit strong interactions. 相似文献
83.
Hunter M Backman V Popescu G Kalashnikov M Boone CW Wax A Gopal V Badizadegan K Stoner GD Feld MS 《Physical review letters》2006,97(13):138102
Light scattered from biological tissues can exhibit an inverse power law spectral component. We develop a model based on the Born approximation and von Karman (self-affine) spatial correlation of submicron tissue refractive index to account for this. The model is applied to light scattering spectra obtained from excised esophagi of normal and carcinogen-treated rats. Power law exponents used to fit dysplastic tissue site spectra are significantly smaller than those from normal sites, indicating that changes in tissue self-affinity can serve as a potential biomarker for precancer. 相似文献
84.
We address risk minimizing option pricing in a regime switching market where the floating interest rate depends on a finite state Markov process. The growth rate and the volatility of the stock also depend on the Markov process. Using the minimal martingale measure, we show that the locally risk minimizing prices for certain exotic options satisfy a system of Black-Scholes partial differential equations with appropriate boundary conditions. We find the corresponding hedging strategies and the residual risk. We develop suitable numerical methods to compute option prices. 相似文献
85.
Krushelnick K Rozmus W Wagner U Beg FN Bochkarev SG Clark EL Dangor AE Evans RG Gopal A Habara H Mangles SP Norreys PA Robinson AP Tatarakis M Wei MS Zepf M 《Physical review letters》2008,100(12):125005
Experiments were performed in which intense laser pulses (up to 9x10(19) W/cm(2)) were used to irradiate very thin (submicron) mass-limited aluminum foil targets. Such interactions generated high-order harmonic radiation (greater than the 25th order) which was detected at the rear of the target and which was significantly broadened, modulated, and depolarized because of passage through the dense relativistic plasma. The spectral modifications are shown to be due to the laser absorption into hot electrons and the subsequent sharply increasing relativistic electron component within the dense plasma. 相似文献
86.
Research on Chemical Intermediates - This work aims to develop and study sol–gel-derived anticorrosion films for mild steel. Epoxy bis-silane precursor has been prepared by reaction of liquid... 相似文献
87.
Tamil Selvi Gopal Soon Kwan Jeong Tahani A. Alrebdi Saravanan Pandiaraj Abdullah Alodhayb Muthumareeswaran Muthuramamoorthy 《Materials Today Chemistry》2022
A recently discovered 2D transition titanium metal carbides also called as MXenes (Ti3C2Tx)-based nanocomposite was prepared with Cu2O through wet precipitation technique, and these materials were further developed as the electrode for sensing glucose by chronoamperometry technique. The prepared MXene-Cu2O (Ti3C2Tx-Cu2O) nanocomposite was characterized by XRD, FTIR, UV–Vis spectroscopy, FE-SEM, EDAX, and Raman spectroscopy. Morphological studies of the composites revealed that the micro-octahedral shape of Cu2O is distributed on the surface of MXene with size larger than bare Cu2O. Further, the prepared composite material was fabricated as a sensing probe, and the electrochemical activities were examined by cyclic voltammetric analysis (CV) and chronoamperometric (CA) methods. From the CV and CA investigation, the current response was higher for the composite than the bare material (Cu2O & MXene) in the presence of glucose. The amperometric investigation of MXene-Cu2O composite for the detection of glucose shows a broad linear range (0.01–30 mM) with a sensitivity of 11.061/μAmM cm?2 and a detection limit of 2.83 μM. Further, the fabricated sensor exhibits good selectivity with interfering species like NaCl, fructose, sucrose, urea, ascorbic acid, lactose, short response time, stability, good reproducibility, and compatibility with human serum sample. From the investigation, the prepared MXene-Cu2O composite is a good candidate for the direct detection of glucose molecules and is also well suitable for clinical diagnosis. 相似文献
88.
89.
Simon G. Bott Alan P. Marchand Duddu Raja Gopal 《Journal of chemical crystallography》1993,23(11):849-855
The syntheses and crystal structures of pentacyclo[9.4.1.05,14.07,13.012,15]hexadecane-3,9-dione (2), a novel C16 diketone with potential inclusion ability, and the products of the reaction of2 withn-butyllithium andmeso-erythritol (i.e.,meso-1,2,3,4-butanetetrol) are described. Crystal data:2·H2O, orthorhombic,Pmmn,a=10.7385(8),b=9.0188(6),c=6.8411(4)Å,V=662.55(7)Å3, andR=0.039 (379 reflections);3 (product from reaction withn-butyllithium), triclinic,P¯1,a=8.7192(7),b=10.9351(8),c=12.1842(8)Å,=68.933(5),=75.850(6), =80.309(6)°,V=1047.0(1)Å3, andR=0.081 (1811 reflections);4 (product from reaction with erythritol), triclinic,P¯1,a=7.7224(8),b=10.1976(8),c=10.7021(9)Å,=85.405(7),=85.766(8), =76.056(7)°,V=814.0(1)Å3, andR=0.052 (1471 reflections). 相似文献
90.
The cytotoxic natural product (+)-crocacin C ( 1) has been synthesized in 10 linear steps from commercially available Evans' chiral propionimide in 5% overall yield (8 steps from Evans' chiral dipropionate synthon). No protecting groups were utilized. 相似文献