全文获取类型
收费全文 | 179篇 |
免费 | 7篇 |
专业分类
化学 | 134篇 |
晶体学 | 8篇 |
力学 | 13篇 |
数学 | 12篇 |
物理学 | 19篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 14篇 |
2020年 | 14篇 |
2019年 | 3篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 16篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 11篇 |
2012年 | 10篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有186条查询结果,搜索用时 15 毫秒
31.
The numerical predictions confirm a new classification of flow patterns of triple jet interaction. The addition of side jets increase the rate of decrease of the centreline velocity for the flow of type A and decreases in the other cases. The effect of various types of flow on the rate of decrease of the velocity, the turbulent kinetic energy and the temperature in the combined region are detailed. Several correlations are proposed. 相似文献
32.
Background
Rosiglitazone (ROZ) and glimepiride (GLM) are antidiabetic agents used in the treatment of type 2 diabetes mellitus. A survey of the literature reveals that only one spectrophotometric method has been reported for the simultaneous determination of ROS and GLM in pharmaceutical preparations. However the reported method suffers from the low sensitivity, for this reason, our target was to develop a simple sensitive HPLC method for the simultaneous determination of ROZ and GLM in their combined dosage forms and plasma. 相似文献33.
Mamdouh S. Masoud Amina A. Soayed Ahmed S. Elkholany 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1123-1130
The reaction of 99mTc of different oxidation states (+7, +4) with 2-thiouracil and 5-nitrobarbituric acid have been studied at different temperatures,
pH and concentrations. The reaction mixtures have been analyzed at different times using thin layer chromatography (TLC) and
a radio detector to show the peaks at the plates. 99mTc is obtained from the Mo generators with oxidation state (+7). The use of SnCl2 as a reducing agent gave 99mTc with oxidation state (+4). It is very difficult to separate the complexes formed from the reactions in very small concentration.
The percentage of 99mTc and its oxidation state involved in the complexes can be determined. The labeling efficiencies (percentage of complex)
in the reaction of 99mTc+7 with 5-nitro-barbituric-acid increases mostly at pH 10. Both oxidation states of 99mTc(+7, +4) can be detected at pH’s 4 and 10, but at pH 4, the reduced form 99mTCO2, is more pronounced. At pH 7 no complexes were detected and most of 99mTc remains as 99mTCO4
−
. By increasing the ligand concentration, the labeling efficiencies of the complex increases. For the reaction of 99mTc of oxidation states (+4, +7) with 2-thiouracil at different temperatures and analytical times it is concluded that several
complexes with different Rf values were observed in equilibrium and most of these complexes were unstable. 相似文献
34.
Yanling Li Amina Benchohra Buqin Xu Benoît Baptiste Keevin Bneut Paraskevas Parisiades Ludovic Delbes Alain Soyer Kamel Boukheddaden Rodrigue Lescouëzec 《Angewandte Chemie (International ed. in English)》2020,59(39):17272-17276
A key challenge in the design of magnetic molecular switches is to obtain bistability at room temperature. Here, we show that application of moderate pressure makes it possible to convert a paramagnetic FeIII2CoII2 square complex into a molecular switch exhibiting a full dia‐ to paramagnetic transition: FeIICoIII ? FeIIICoII. Moreover, the complex follows a rare behavior: the higher the pressure, the broader the magnetic hysteresis. Thus, the application of an adequate pressure allows inducing a magnetic bistability at room temperature with predictable hysteresis width. The structural studies at different pressures suggest that the pressure‐enhanced bistability is due to the strengthening of intermolecular interactions upon pressure increase. An original microscopic Ising‐like model including pressure effects is developed to simulate this unprecedented behavior. Overall, this study shows that FeCo complexes could be very sensitive piezo switches with potential use as sensors. 相似文献
35.
Jeffrey R. Lince Thomas B. Stewart Malina M. Hills Paul D. Fleischauer Jory A. Yarmoff Amina Taleb-Ibrahimi 《Surface science》1989,210(3):387-405
The effect of 1 keV Ne+ bombardment on the clean MoS2(0001)-1 × 1 surface with fluences between 4 × 1014 and 4 × 1016 Ne+/cm2 was studied using high-resolution photoelectron spectroscopy excited with synchrotron radiation. Spectra of the Mo 3d and S 2p core levels were measured with photon energies that ensured that the kinetic energy of the photoelectrons was the same, resulting in the same depth being probed for both core levels. For lower fluences (i.e., 2 × 1015 Ne+/cm2), S vacancy defect formation occurs in the MoS2 lattice, with the concurrent formation of a small amount (< 10%) of dispersed elemental molybdenum [Mo(0)]. For fluences greater than l × 1016 Ne+/cm2, the Mo(0) is the predominant species in the surface region, while the remaining species consist of amorphous MoS2−x and polysulfide species. Valence band spectra taken with photon energies of 152 and 225 eV were consistent with the core level results. The movement of the valence band maximum toward the Fermi level indicated the formation of a metallic surface region. Annealing the sample to temperatures up to 1000 K resulted in the formation of metallic Mo coexisting, in approximately equal amounts, with reformed MoS2 in a surface with no long-range order as determined by LEED. Finally, a qualitative depth distribution of the chemical species present after Ne+ bombardment was determined by varying the photon energies used for the core level spectra. The results indicate that the preferential sputtering of sulfur over molybdenum occurs predominantly through a mechanism involving chemical bonding effects, specifically, through the preferential emission of polysulfide ions over other species in the bombarded region. 相似文献
36.
37.
38.
Tabti Hadja Alia Adjdir Mehdi Ammam Abdelkader Mdjahed Baghdad Guezzen Brahim Ramdani Amina Benddedouche Choukry Kamel Bouchikhi Noria Chami Nadir 《Research on Chemical Intermediates》2020,46(12):5377-5390
Research on Chemical Intermediates - A range of Cu-LDHs has been synthesized by co-precipitation using metal nitrate precursors and sodium carbonate under varying molar ratios Cu/Al... 相似文献
39.
Amina Khettabi Arkadiusz Grempka Dr. Frederic Lafolet Elarbi Chatir Dr. Nicolas Leconte Dr. Marie-Noelle Collomb Dr. Damien Jouvenot Dr. Saioa Cobo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(59):13359-13362
A pyridinium substituted dithienylethene derivative was used for the first time as an efficient photoreducing agent of two different substrates. This reaction exhibits high catalytic yields due to the continuous regeneration of the initial state of the photochromic molecule. 相似文献
40.
Two metaheuristic methods based on Tabu search are introduced to assign judges to individual competitions in a tournament.
The complexity of the mathematical formulation accounting for the assignment rules, leads us to use such an approach. The
first metaheuristic includes two different Tabu searches that are combined with a diversification strategy. The second metaheuristic
is applied to a penalized version of the original model formulated as an assignment problem. This metaheuristic is also based
on a Tabu search procedure including a diversification strategy driven by the constraints violated. Numerical results are
provided to indicate the efficiency of the methods to generate very good solutions. 相似文献