全文获取类型
收费全文 | 247篇 |
免费 | 20篇 |
国内免费 | 3篇 |
专业分类
化学 | 119篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 80篇 |
物理学 | 65篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 14篇 |
2018年 | 14篇 |
2017年 | 6篇 |
2016年 | 20篇 |
2015年 | 7篇 |
2014年 | 13篇 |
2013年 | 28篇 |
2012年 | 20篇 |
2011年 | 21篇 |
2010年 | 23篇 |
2009年 | 18篇 |
2008年 | 13篇 |
2007年 | 8篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 4篇 |
1999年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1979年 | 5篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
排序方式: 共有270条查询结果,搜索用时 31 毫秒
81.
82.
Siqi Zhang Banu Taktak Karaca Sarah Kay VanOosten Esra Yuca Suntharavathanan Mahalingam Mohan Edirisinghe Candan Tamerler 《Macromolecular rapid communications》2015,36(14):1322-1328
Nanofibers featuring functional nanoassemblies show great promise as enabling constituents for a diverse range of applications in areas such as tissue engineering, sensing, optoelectronics, and nanophotonics due to their controlled organization and architecture. An infusion gyration method is reported that enables the production of nanofibers with inherent biological functions by simply adjusting the flow rate of a polymer solution. Sufficient polymer chain entanglement is obtained at Berry number > 1.6 to make bead‐free fibers integrated with gold nanoparticles and proteins, in the diameter range of 117–216 nm. Integration of gold nanoparticles into the nanofiber assembly is followed using a gold‐binding peptide tag genetically conjugated to red fluorescence protein (DsRed). Fluorescence microscopy analysis corroborated with Fourier transform infrared spectroscopy (FTIR) data confirms the integration of the engineered red fluorescence protein with the nanofibers. The gold nanoparticle decorated nanofibers having red fluorescence protein as an integral part keep their biological functionality including copper‐induced fluorescence quenching of the DsRed protein due to its selective Cu+2 binding. Thus, coupling the infusion gyration method in this way offers a simple nanoscale assembly approach to integrate a diverse repertoire of protein functionalities into nanofibers to generate biohybrid materials for imaging, sensing, and biomaterial applications.
83.
Erhan Albayrak 《中国物理快报》2011,28(2):43-46
The negativity (N) as a measure of thermal entanglement (TE) is studied for a two-qutrit spin-1 anisotropic Heisenberg XXZ chain with Dzyaloshinskii-Moriya (DM)... 相似文献
84.
Erhan Albayrak 《Journal of magnetism and magnetic materials》2011,323(22):2846-2850
The effects of crystal field (Δ) which is randomly turned on with probability p or turned off with probability 1−p on the sites of the Bethe lattice are investigated to study the critical behavior of the spin-3/2 Blume-Capel model. The order-parameters are obtained in terms of the recursion relations and then the possible phase diagrams are calculated at finite temperatures for given system parameters p, Δ and coordination numbers z=3, 4, 5 and 6. It was found that the phase diagrams change drastically for given probability and randomness. The first-order phase transitions are only found for higher p values and the lines of which get shorter and eventually disappear as p decreases. The critical lines do not present any qualitative differences with z, but they are seen at higher temperatures for higher z. 相似文献
85.
S. Erhan W. Lockman M. Medinnis T. Meyer J. Rander P. Schlein R. Webb A. Boehm H. Foeth A. Staude R. Ellis B. Naroska P. Strolin J. Zsembery 《Physics letters. [Part B]》1979,82(2):301-304
Λ0's produced in the inclusive reaction pp → Λ° + X with √s = 53 and 62 GeV at the CERN Intersecting Storage Rings are observed to be polarized along the normal to the production plane. In the ranges of longitudinal and transverse momenta, 15–24 and 0.6-1.4 GeV/c, respectively, the mean polarization is found to be ?(0.357±0.055). 相似文献
86.
At the interface of water-organic two-phase systems benzenediazonium salts couple with 1-naphthol preferentially at the 2-position. 相似文献
87.
The present study was designed to examine the chemical composition of the essential oil, in vitro antioxidant activity and total phenolic and flavonoid content of extracts from plant parts (leaf, flower and stem) of Teucrium alyssifolium. The principle components of the essential oil were trans-β-caryophyllene (16.87%), ar-curcumene (11.43%) and bisabolene (11.06%), representing 39.36% of the oil. The total phenolic contents ranged between 13.99 and 41.54 mg of GAE/g of extract. The concentrations of flavonoids varied from 16.82 to 49.52 mg of Ru/g of extract. Antioxidant activity was determined in vitro using DPPH reagent and expressed as concentration of each extract required to inhibit radical by 50% (IC50) values that ranged from 13.52 to 132.55 μg/ml. Our results have indicated that water extract of T. alyssifolium (part leaf) with a total content of polyphenols (41.54 mg of GAE/g) and an IC50 of 13.52 μg/ml is more antioxidant. 相似文献
88.
Despite the increasing number of applications of biosensors in many fields, the construction of a steady biosensor remains still challenging. The high stability of molecularly bio-imprinted enzymes for its substrate can make them ideal alternatives as recognition elements for sensors. Urease (urea aminohydrolase, EC 3.5.1.5), which catalysis the hydrolysis of urea to ammonia and carbon dioxide, has been used in immobilized form in artificial kidney for blood detoxification. According to one report approximately half a million patients worldwide are being supported by haemodialysis. In this study, the enzyme of urease was first complexed by using a substrate analogue, thiourea, in aqueous medium and then this enzyme was immobilized on gelatin by crosslinking with glutaraldehyde on a glass electrode surface. Similarly, urease noncomplexed with thiourea was also immobilized on a glass electrode in the same conditions. The aim of the study was to compare the two biosensors in terms of their repeatability, pH stability and thermal stability, and also, linear ranges of two biosensors were compared with each other. 相似文献
89.
V. I. Bodnarchuk V. V. Sadilov S. A. Manoshin R. Erhan M. V. Avdeev S. P. Yaradaikin 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2016,10(6):1129-1132
The sensitivity of the spin-echo small-angle neutron scattering technique based on magnetic fields that increase linearly with time is analyzed depending on the scattering geometry and the detector apperture. The application of sectoral collimators for the selection of scattering neutron trajectories is substantiated with the aim of improving the resolution and the corresponding effect on the data acquisition time is estimated. 相似文献
90.
E. Ö. Karaca M. Akkoç E. Öz S. Altin V. Dorcet T. Roisnel 《Journal of Coordination Chemistry》2017,70(7):1270-1284
A new series of ring-expanded six- and seven-membered N-heterocyclic carbene precursors (re-NHCs) and their transition metal complexes were synthesized. The basic properties of the synthesized materials were investigated by density functional theory (DFT). The six- and seven-membered re-NHCs were synthesized in good yield via reaction of the corresponding alkyldibromides or alkyldiiodides with N,N′-bis-(2-phenylbenzene)formamidine in the presence of K2CO3 under aerobic conditions. Complexes, represented by the formula [ML1,2(COD)Cl] (where M = Ir or Rh and L is a ring-expanded N-heterocyclic carbene ligand), were synthesized in the presence of the corresponding free carbene and iridium or rhodium metal precursors in tetrahydrofuran. All new re-NHC complexes were characterized by different analytical techniques, including NMR spectroscopy, X-ray diffraction, UV spectroscopy and elemental analysis. According to molecular electrostatic potential calculations, the electrophilic properties of the complexes were aligned, from highest to lowest, as Ir-6-DiPh, Rh-6-DiPh and Ir-7-DiPh. The HOMO, LUMO and energy gaps of the complexes were calculated by DFT. On the basis of the DFT analysis, it can be predicted that Rh-6-DiPh is the most stable complex and Ir-7-DiPh is more reactive than Ir-6-DiPh. 相似文献