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371.
A.K. Panda Seema KumariI. Chattoraj M. GhoshA. Mitra 《Journal of magnetism and magnetic materials》2007
The investigation addresses the electron transport properties of Co71−xFexCr7Si8B14 (x=0, 2, 3.2, 4, 6, 8 and 12 at%) amorphous alloys. The variation in electrical resistivity of as-cast amorphous materials with thermal scanning from room temperature to 1000 K was measured. The CoFe-based alloys revealed an initial decrease in temperature coefficient of resistivity (TCR), a characteristic of spin-wave phenomena in glassy metallic systems. This behaviour in the present alloys was in a sharp contrast to the Co-based amorphous materials that indicate the drop in resistivity much below room temperature. In the studied alloys, the variation in initial TCR values and the full-width at half-maxima determined from X-ray diffraction of as-quenched materials exhibited a similar trend with increasing Fe content, indicating the compositional effect of near neighbouring atoms. After the initial decrease in resistivity, all the alloys indicated a subsequent increase at Tmin. The Curie temperature (TC), which was measured from thermal variation of ac susceptibility showed non-monotonic change with Fe content. In the temperature range between Tmin and TC the relative scattering by electron-magnon and electron-phonon resulted in the non-monotonic change in Curie temperature. At crystallization onset (TX1) all the alloys except there with X=6, showed a sharp decrease in electrical resistivity which was attributed to ordering phenomena. In contrast to this resistivity decrease, X=6 alloy exhibited a drastic increase in resistivity around TX1 observed during amorphous to nanocrystalline transformation. Such nanocrystalline state was observed by Transmission electron microscopy. 相似文献
372.
Studies on tandem ene/intramolecular diels-alder reactions 总被引:1,自引:0,他引:1
Raymond J. Giguere Andrew M. Namen Blanca O. Lopez Aravind Arepally Danielle E. Ramos George Majetich Jean Defauw 《Tetrahedron letters》1987,28(52):6553-6556
Tandem ene/intramolecular Diels-Alder reactions of 1,4-cyclohexadiene and
- or
-activated acetylenes are optimized. Analogous reactions with disubstituted bicyclohexa-1,4-dienes regioselectively produce highly functionalized tetracyclic adducts. 相似文献
373.
S.K. Vasisht Tripat P. Kaur Jyotsna Kaushal Seema Dixit 《Journal of organometallic chemistry》1997,540(1-2):51-54
Sodium bis(trimethylstannyl)amide NaN(SnMe3)2, isolated by the reaction of trimethylstannyldiethylamine with sodium amide, reacts with tris(trimethylsilyl)hydrazino—dichloro-phosphine to form bis(trimethylsilyl)bis(trimethylstannyl)-2-phospha-2-tetrazene, (Me3Si)2N-N=P-N(SnMe3)2. Both the molecules have been isolated and characterized. 相似文献
374.
Balaswamy P. Aravind S. Purushotham Reddy S. Satyanarayana B. 《Russian Journal of General Chemistry》2018,88(4):774-779
An efficient, eco-friendly synthesis of a series of 2-{[3-oxo-3-(alkyl/aryl-1-yl)alkyl]thio}-3-substituted quinazolin-4(3H)-ones employing quinazolin-4(3H)-one and corresponding halo-acyl/haloalkyl as electrophiles is presented. The products were assayed for anti-bacterial activity on four bacterial species (Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis, and Staphylococcus aureus). In-silico molecular docking studies were carried out.
相似文献375.
376.
Various routes to a variety of azridine‐2‐carboxylates have been described and the stereochemistry of these compounds has been determined by spectroscopic methods. Further, greater diversity of β‐lactams via ring expansion of these azridines‐2‐carboxylates were obtained by a general, efficient and direct stereospecific approach. 相似文献
377.
The structural, electronic and magnetic properties of Co-based Heusler compounds Co2YZ (Y = V, Cr; Z = Al, Ga) under pressure are studied using first principles density functional theory. The calculations are performed within generalized gradient approximation. The total magnetic moment decreases slightly on compression. Under application of external pressure, the valence band and conduction band are shifted downward which leads to the modification of electronic structure. There exists an indirect band gap along Г–X for all the alloys studied. Co2CrAl shows half-metallic nature up to 85 GPa. After this pressure transition from true half-metallic behavior to nearly half-metallic behavior is observed and at 90 GPa it shows metallic behavior. Co2CrGa shows nearly half-metallic behavior at ambient pressure, but true half-metallic behavior is observed as pressure is increased to 100 GPa. For Co2VGa, true half-metallic to nearly half-metallic transition is observed at 40 GPa and around 100 GPa, Co2VGa shows metallic behavior. For Co2VAl, true half-metallic behavior is not observed at ambient as well as higher pressures. The half metal-to-metal transition in Co2VAl and Co2CrAl is accompanied by quenching of magnetic moment. 相似文献
378.
Subhash Chander Seema Lakhanpal Anjali Krishnamurthy Bipin K. Srivastava V. K. Aswal 《Pramana》2004,63(2):345-350
Magnetization measurements are reported on a nano-particle sample of Znsubstituted spinel ferrite Fe2.8Zn0.2O4 in the temperature range 20–300 K. Analysis of small-angle neutron scattering data shows the sample to have a log-normal particle size distribution of median diameter 64.4 Å and standard deviation 0.38. Magnetization evolves over a long period of timet going nearly linearly with logt. Magnetic anisotropy, estimated by fitting M-logt curve, shows many fold increase over that of bulk particle sample. Major enhancement owes to disordered moments in surface layer. In the nano-particle state as well increasing amount of Zn causes anisotropy to decrease. 相似文献
379.
380.
David G. Harris Ehab Morsy Gopal Pandurangan Peter Robinson Aravind Srinivasan 《Random Structures and Algorithms》2016,49(2):322-344
Basic graph structures such as maximal independent sets (MIS's) have spurred much theoretical research in randomized and distributed algorithms, and have several applications in networking and distributed computing as well. However, the extant (distributed) algorithms for these problems do not necessarily guarantee fault‐tolerance or load‐balance properties. We propose and study “low‐average degree” or “sparse” versions of such structures. Interestingly, in sharp contrast to, say, MIS's, it can be shown that checking whether a structure is sparse, will take substantial time. Nevertheless, we are able to develop good sequential/distributed (randomized) algorithms for such sparse versions. We also complement our algorithms with several lower bounds. Randomization plays a key role in our upper and lower bound results. © 2016 Wiley Periodicals, Inc. Random Struct. Alg., 49, 322–344, 2016 相似文献