全文获取类型
收费全文 | 405篇 |
免费 | 17篇 |
国内免费 | 3篇 |
专业分类
化学 | 299篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 50篇 |
物理学 | 67篇 |
出版年
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 3篇 |
2016年 | 17篇 |
2015年 | 19篇 |
2014年 | 13篇 |
2013年 | 28篇 |
2012年 | 24篇 |
2011年 | 25篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 21篇 |
2007年 | 19篇 |
2006年 | 21篇 |
2005年 | 19篇 |
2004年 | 25篇 |
2003年 | 11篇 |
2002年 | 18篇 |
2001年 | 7篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1992年 | 3篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 11篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1928年 | 1篇 |
1903年 | 1篇 |
1870年 | 1篇 |
1868年 | 1篇 |
1858年 | 3篇 |
排序方式: 共有425条查询结果,搜索用时 15 毫秒
61.
Michelangelo Iannone Stefania Bulotta Donatella Paolino Maria Cristina Zito Santo Gratteri Francesco S Costanzo Domenicantonio Rotiroti 《BMC neuroscience》2006,7(1):13-6
Background
3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) is known for its toxicological, psychopathological and abuse potential. Some environmental conditions, e.g. acoustic stimulation typical of the "rave scene" can influence the toxicity of this drug. 相似文献62.
Recently, two of us argued that the probability that an FK cluster in the Q-state Potts model connects three given points is related to the time-like Liouville three-point correlation function (Delfino and Viti, 2011) [1]. Moreover, they predicted that the FK three-point connectivity has a prefactor which unveils the effects of a discrete symmetry, reminiscent of the SQ permutation symmetry of the Q=2,3,4 Potts model. We revisit the derivation of the time-like Liouville correlator (Zamolodchikov, 2005) [2] and show that this is the only consistent analytic continuation of the minimal model structure constants. We then present strong numerical tests of the relation between the time-like Liouville correlator and percolative properties of the FK clusters for real values of Q. 相似文献
63.
64.
Lauro Tomio M. R. Hadizadeh M. T. Yamashita A. Delfino T. Frederico 《Few-Body Systems》2013,54(7-10):1543-1546
Universal properties of weakly-bound four-boson systems near the scaling limit are discussed by considering recent results obtained from the solution of Faddeev-Yakubovsky (FY) equations, which confirm a previous conjecture on a four-body scale dependence. In the present contribution, within a discussion on our numerical results obtained for the binding energies of two consecutive tetramer states, we are analyzing the relative relevance of the two possible configurations of the four-body system. 相似文献
65.
Giustino Orlando Annalisa Chiavaroli Sabrina Adorisio Domenico V. Delfino Luigi Brunetti Lucia Recinella Sheila Leone Gokhan Zengin Alessandra Acquaviva Paola Angelini Giancarlo Angeles Flores Roberto Venanzoni Simonetta Cristina Di Simone Francesca Di Corpo Andrei Mocan Luigi Menghini Claudio Ferrante 《Molecules (Basel, Switzerland)》2021,26(15)
Prunus mahaleb L. fruit has long been used in the production of traditional liqueurs. The fruit also displayed scavenging and reducing activity, in vitro. The present study focused on unravelling peripheral and central protective effects, antimicrobial but also anti-COVID-19 properties exerted by the water extract of P. mahaleb. Anti-inflammatory effects were studied in isolated mouse colons exposed to lipopolysaccharide. Neuroprotection, measured as a blunting effect on hydrogen-peroxide-induced dopamine turnover, was investigated in hypothalamic HypoE22 cells. Antimicrobial effects were tested against different Gram+ and Gram- bacterial strains. Whereas anti-COVID-19 activity was studied in lung adenocarcinoma H1299 cells, where the gene expression of ACE2 and TMPRSS2 was measured after extract treatment. The bacteriostatic effects induced on Gram+ and Gram- strains, together with the inhibition of COX-2, TNFα, HIF1α, and VEGFA in the colon, suggest the potential of P. mahaleb water extract in contrasting the clinical symptoms related to ulcerative colitis. The inhibition of the hydrogen peroxide-induced DOPAC/DA ratio indicates promising neuroprotective effects. Finally, the downregulation of the gene expression of ACE2 and TMPRSS2 in H1299 cells, suggests the potential to inhibit SARS-CoV-2 virus entry in the human host. Overall, the results support the valorization of the local cultivation of P. mahaleb. 相似文献
66.
Delfino Chamorro-Arenas Alejandro A. Nolasco-Hernández Dr. Lilia Fuentes Dr. Leticia Quintero Prof. Dr. Fernando Sartillo-Piscil 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(21):4671-4676
Remote and multiple functionalization of piperidines without the use of transition-metal catalysts and elaborate directing groups is one of the major challenges in organic synthesis. Herein is reported an unprecedented two-step protocol that enables the multiple functionalization of piperidines to either 4-substituted or trans-3,4-disubstituted 2-piperidones. First, by exploiting the duality of TEMPO reactivity, which under oxidative and thermal conditions fluctuates between cationic and persistent-radical form, a novel multiple C(sp3)-H oxidation of piperidines to α,β-unsaturated 2-piperidones was developed. Second, the intrinsic low reactivity of the unsaturated piperidones toward conjugated Grignard additions was overcome by using trimethylsilyl chloride (TMSCl) as Lewis acid. Subsequently, conjugated Grignard addition/electrophilic trapping protocol provided substituted 2-piperidone intermediates, some of which were then transformed into pharmaceutical alkaloids. 相似文献
67.
Donatella Senatra C. Ziparo Cecilia M. C. Gambi L. Lanzi 《Journal of Thermal Analysis and Calorimetry》2008,92(2):535-541
A water-in-oil microemulsion composed of water, AOT and decane with volume fraction φ=0.50 and molar ratio X=40.8 was analysed by DSC. The percolation and the bicontinuous transitions as well as the melting endotherms and the freezing
exotherms were measured. The main attention was focussed on the system energy balance. It was found that, by freezing the
samples after the occurrence of the percolative transition, the total heat released is significantly less than the heat absorbed
in the melting endotherms. A simple geometrical model was used as an analysis tool of the aforementioned energy difference.
Since the system studied exhibits a percolative transition of dynamic type, on approaching the percolation threshold temperature
(T≤T
p) and a static percolation for T≥T
p, the structural change from the connecting water-droplet-cluster to a connecting water channel was schematised in the model
as a change from a sphere-necklace to a water-cylindrical channel of equal volume and equal length. The surface energy associated
with the formation of the two different geometrical surfaces was evaluated and the amount of saved energy compared with the
experimentally measured one. 相似文献
68.
Gelmi ML Nava D Leone S Pellegrino S Baldelli E Zunino F Cappelletti G Cartelli D Fontana G 《The Journal of organic chemistry》2008,73(22):8893-8900
The synthesis of new D-seco-C-nor-taxane derivatives in which the D-ring has been deleted and the C-ring has been transformed into a new pentatomic ring, i.e., the polyfunctionalized tetrahydrofuranosyl and cyclopentenyl or cyclopentyl ring, was performed starting from baccatin III derivatives. The synthetic strategy adopted took advantage of the oxetane ring opening and disconnection of the C4-C5 bond, followed by an intramolecular condensation. The formation of furanosyl or cyclopentyl rings is strictly dependent on the presence of unprotected or protected oxygen at C-7 in the starting material. The reactions proceeded with good diastereoselectivity with control of the stereochemistry of one or two stereocenters. 相似文献
69.
Dr. Pablo Pinacho Dr. Donatella Loru Dr. Tatjana Šumanovac Dr. Marina Šekutor Prof. Dr. Melanie Schnell 《Chemphyschem》2023,24(23):e202300561
We report on the synthesis and characterization using high-resolution rotational spectroscopy of three bulky thioethers that feature an adamantyl group connected to a sulfur atom. Detailed experimental and theoretical structures are provided and compared with the 1,1′-diadamantyl ether. In addition, we expand on previous findings concerning microsolvation of adamantyl derivatives by investigating the cluster formation between these thioethers and a water molecule. The investigation of such clusters provides valuable insights into the sulfur-centered hydrogen bonding in thioethers with increasing size and steric repulsion. 相似文献
70.
Casa G Parretta DA Castrillo A Wehr R Gianfrani L 《The Journal of chemical physics》2007,127(8):084311
An intensity-stabilized laser absorption spectrometer, which incorporates a mirror-extended cavity diode laser, a temperature-stabilized gas cell, and a Michelson interferometer, was developed and applied to a highly accurate investigation of line intensity factors within the nu(1)+2nu(2) (0)+nu(3) combination band of carbon dioxide, around 2 microm wavelength, at a temperature of 296.0 K. This relatively complex apparatus enables one to observe the absorption line shape with high precision and accuracy in such a way that it is possible to retrieve the integrated absorbance with a relative uncertainty better than 0.1%. The absorption spectra were interpolated with the uncorrelated strong-collision model of Rautian and Sobel'man in order to take into account Dicke narrowing effects, thus obtaining an agreement at a level of a few parts per 10(-5). We report line strength values for the R(2)-R(18) transitions with an unprecedented level of accuracy, in the range between 0.1% and 0.15%. Finally, we discuss the possibility of providing a first experimental test of the theoretical model for molecular line strengths based on the Herman-Wallis expansion. 相似文献