全文获取类型
收费全文 | 277篇 |
免费 | 8篇 |
专业分类
化学 | 208篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 20篇 |
物理学 | 53篇 |
出版年
2023年 | 2篇 |
2021年 | 10篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 13篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 17篇 |
2012年 | 9篇 |
2011年 | 22篇 |
2010年 | 12篇 |
2009年 | 14篇 |
2008年 | 15篇 |
2007年 | 19篇 |
2006年 | 20篇 |
2005年 | 11篇 |
2004年 | 17篇 |
2003年 | 12篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1972年 | 1篇 |
1962年 | 1篇 |
1958年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有285条查询结果,搜索用时 15 毫秒
1.
Domenico Franco Giovanna Calabrese Salvatore Petralia Giulia Neri Carmelo Corsaro Lucia Forte Stefano Squarzoni Salvatore Guglielmino Francesco Traina Enza Fazio Sabrina Conoci 《Molecules (Basel, Switzerland)》2021,26(4)
Hydroxyapatite (HA) is the main inorganic mineral that constitutes bone matrix and represents the most used biomaterial for bone regeneration. Over the years, it has been demonstrated that HA exhibits good biocompatibility, osteoconductivity, and osteoinductivity both in vitro and in vivo, and can be prepared by synthetic and natural sources via easy fabrication strategies. However, its low antibacterial property and its fragile nature restricts its usage for bone graft applications. In this study we functionalized a MgHA scaffold with gold nanorods (AuNRs) and evaluated its antibacterial effect against S. aureus and E. coli in both suspension and adhesion and its cytotoxicity over time (1 to 24 days). Results show that the AuNRs nano-functionalization improves the antibacterial activity with 100% bacterial reduction after 24 h. The toxicity study, however, indicates a 4.38-fold cell number decrease at 24 days. Although further optimization on nano-functionalization process are needed for cytotoxicity, these data indicated that Au-NRs nano-functionalization is a very promising method for improving the antibacterial properties of HA. 相似文献
2.
3.
At some point, after publication, we realized that Proposition 4.1(2) and Theorem 4.4 in [2] hold under the assumption (not explicitly declared) that B = f(A)+J. Furthermore, we provide here the exact value for the embedding dimension of A?fJ, also when B≠f(A)+J, under the hypothesis that J is finitely generated as an ideal of the ring f(A)+J. 相似文献
4.
F. Nucera A. F. Vakakis D. M. McFarland L. A. Bergman G. Kerschen 《Nonlinear dynamics》2007,50(3):651-677
In the field of seismic protection of structures, it is crucial to be able to diminish ‘as much as possible’ and dissipate
‘as fast as possible’ the load induced by seismic (vibration-shock) energy imparted to a structure by an earthquake. In this
context, the concept of passive nonlinear energy pumping appears to be natural for application to seismic mitigation. Hence, the overall problem discussed in this paper can be formulated
as follows: Design a set of nonlinear energy sinks (NESs) that are locally attached to a main structure, with the purpose of passively
absorbing a significant part of the applied seismic energy, locally confining it and then dissipating it in the smallest possible
time. Alternatively, the overall goal will be to demonstrate that it is feasible to passively divert the applied seismic energy
from the main structure (to be protected) to a set of preferential nonlinear substructures (the set of NESs), where this energy
is locally dissipated at a time scale fast enough to be of practical use for seismic mitigation. It is the aim of this work to show that the concept of nonlinear energy pumping is feasible for seismic mitigation. We consider
a two degree-of-freedom (DOF) primary linear system (the structure to be protected) and study seismic-induced vibration control
through the use of Vibro-Impact NESs (VI NESs). Also, we account for the possibility of attaching to the primary structure additional alternative NES configurations
possessing essential but smooth nonlinearities (e.g., with no discontinuities). We study the performance of the NESs through
a set of evaluation criteria. The damped nonlinear transitions that occur during the operation of the VI NESs are then studied
by superimposing wavelet spectra of the nonlinear responses to appropriately defined frequency – energy plots (FEPs) of branches
of periodic orbits of underlying Conservative systems. 相似文献
5.
Francesco Mallamace Carmelo Corsaro Enza Fazio Sow-Hsin Chen Domenico Mallamace 《中国科学:物理学 力学 天文学(英文版)》2019,(10)
We study the hydrogen bonds effect on the water density as a function of temperature and pressure from the supercritical region to the metastable supercooled and amorphous phases. We identify two important thermodynamic thresholds, that is P~*2■kbar and T~*■315 K, that separate two different water behaviors in terms of hydrogen bonding capability. For T T~* and P P~* the formation and stability of hydrogen bonded local structures are enhanced. The additional analyses of the proton NMR chemical shift and of the relaxation time confirm this evidence and highlight the structure breaking effects of the pressure. The investigation of both structural and dynamical quantities allow us to draw a complete picture of the water properties in terms of the temperaturepressure dependence of hydrogen bonding. 相似文献
6.
Domenico Grasso Carmelo La Rosa Antonio Raudino Felice Zuccarello 《Liquid crystals》2013,40(12):1699-1705
Abstract Scanning dilatometric and calorimetric measurements were performed in order to obtain information on correlations between various phenomena involving a lipid vesicle. Scanning dilatometry has been shown to be a fast and reliable tool which gives complementary information to that obtained using differential scanning calorimetry and also, provides a means with which to follow dynamic processes without the introduction of perturbing probes into the lipid matrix. The systems examined were vesicles built up from mixtures of neutral and charged lipids in the presence of mono- and divalent inorganic cations. The studied processes were the gel-liquid crystal transition, lateral phase separation in mixed lipid vesicles and fusion between vesicles. 相似文献
7.
Lanthanide Identity Governs Guest-Induced Dimerization in LnIII[15-MC
N(L-pheHA)-5])3+ Metallacrowns
Prof. Carmelo Sgarlata Bernadette L. Schneider Valeria Zito Dr. Rossella Migliore Prof. Matteo Tegoni Prof. Vincent L. Pecoraro Prof. Giuseppe Arena 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(70):17669-17675
Series of lanthanide-containing metallic coordination complexes are frequently presented as structurally analogous, due to the similar chemical and coordinative properties of the lanthanides. In the case of chiral (LnIII[15-MC N(L-pheHA)-5])3+ metallacrowns (MCs), which are well established supramolecular hosts, the formation of dimers templated by a dicarboxylate guest (muconate) in solution of neutral pH is herein shown to have a unique dependence on the identity of the MC's central lanthanide. Calorimetric data and nuclear magnetic resonance diffusion studies demonstrate that MCs containing larger or smaller lanthanides as the central metal only form monomeric host-guest complexes whereas analogues with intermediate lanthanides (for example, Eu, Gd, Dy) participate in formation of dimeric host-guest-host compartments. The driving force for the dimerization event across the series is thought to be a competition between formation of highly stable MCs (larger lanthanides) and optimally linked bridging guests (smaller lanthanides). 相似文献
8.
9.
Prof. Giuseppe Alibrandi Dr. Valeria Amendola Dr. Greta Bergamaschi Dr. Riccardo Dollenz Prof. Luigi Fabbrizzi Prof. Maurizio Licchelli Dr. Carmelo Lo Vecchio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3729-3734
The combined activity of the 1.1.1‐cryptand and of a dicopper(II) bistren cryptate complex including chloride makes the Cl? ion be continuously and slowly delivered to the solution, without any external intervention. The 1.1.1‐cryptand slowly releases OH? ions, according to a defined kinetics, and each OH? ion displaces a Cl? ion from the cryptate. Chloride displacement induces a sharp colour change from bright yellow to aquamarine and can be conveniently monitored spectrophotometrically, even in diluted solutions. The 1.1.1‐cryptand is the motor of a molecular dispenser (the dicopper(II) cryptate) delivering chloride ion automatically, from the inside of the solution. 相似文献
10.
Dr. Antoine Demont Dr. Carmelo Prestipino Dr. Olivier Hernandez Dr. Erik Elkaïm Serge Paofai Prof. Nikolaï Naumov Dr. Bruno Fontaine Prof. Régis Gautier Dr. Stéphane Cordier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(38):12711-12719
The crystal structure of Cs2BaTa6Br15O3 has been elucidated by using synchrotron X‐ray powder diffraction and absorption experiments. It is built from edge‐bridged octahedral [(Ta6${{\rm Br}{{{\rm i}\hfill \atop 9\hfill}}}$ ${{\rm O}{{{\rm i}\hfill \atop 3\hfill}}}$ )${{\rm Br}{{{\rm a}\hfill \atop 6\hfill}}}$ ]4? cluster units with a singular poor metallic electron (ME) count equal to thirteen. This leads to a paramagnetic behaviour related to one unpaired electron. The arrangement of the Ta6 clusters is similar to that of Cs2LaTa6Br15O3 exhibiting 14‐MEs per [(Ta6${{\rm Br}{{{\rm i}\hfill \atop 9\hfill}}}$ ${{\rm O}{{{\rm i}\hfill \atop 3\hfill}}}$ )${{\rm Br}{{{\rm a}\hfill \atop 6\hfill}}}$ ]5? motif. The poorer electron‐count cluster presents longer metal–metal distances as foreseen according to the electronic structure of edge‐bridged hexanuclear cluster. Density functional theory (DFT) calculations on molecular models were used to rationalise the structural properties of 13‐ and 14‐ME clusters. Periodic DFT calculations demonstrate that the electronic structure of these solid‐state compounds is related to those of the discrete octahedral units. Oxygen–barium interactions seem to prevent the geometry of the octahedral cluster to strongly distort, allowing stabilisation of this unprecedented electron‐poor Ta6 cluster in the solid state. 相似文献