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101.
102.
Gangadhara S. Ponrathnam C. Noel D. Reyx F. Kajzar 《Journal of polymer science. Part A, Polymer chemistry》1999,37(5):513-524
We report the synthesis of a nematic copolymer, P(CBMS‐co‐M3), prepared by free radical polymerization of an equimolecular mixture of p‐(4‐cyanobiphenyl‐4′‐yloxy)methylstyrene (CBMS) and N‐[3‐(4‐cyanobiphenyl‐4′‐yloxy)propyl]maleimide (M3) and two isotropic alternating copolymers, P(S‐alt‐Mn) (n = 3,6) prepared by chemical modification of poly(styrene‐alt‐maleimide), P(S‐alt‐M), by n‐(4‐cyanobiphenyl‐4′‐yloxy)alkan‐1‐ol. These copolymaleimides were characterized by NMR, DSC, and optical microscopy. Some corona poling experiments were performed and the second harmonic coefficients d31 and d33 were measured. It was shown that one can gain in net polar ordering by starting with a liquid crystalline system. The ratio d33/d31 was much larger than 3, in agreement with the molecular statistical models for electric field poling of liquid crystals. At ambient conditions, changes of d33 and d31 are 15% over 325 days. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 513–524, 1999 相似文献
103.
104.
Cruz Meneses-Fabian Gustavo Rodriguez-Zurita Maria-del-Carmen Encarnacion-Gutierrez Noel I. Toto-Arellano 《Optics Communications》2009,282(15):3063-3068
A method to reduce the number of captures needed in phase-shifting interferometry is proposed on the basis of grating interferometry and modulation of linear polarization. The case of four interferograms is considered. A common-path interferometer is used with two windows in the object plane and a Ronchi grating as the pupil, thus forming several replicated images of each window over the image plane. The replicated images, under proper matching conditions, superpose in such a way so that they produce interference patterns. Orders 0 and +1 and −1 and 0 form useful patterns to extract the optical phase differences associated to the windows. A phase of π is introduced between these orders using linear polarizing filters placed in the windows and also in the replicated windows, so two π-shifted patterns can be captured in one shot. An unknown translation is then applied to the grating in order to produce another shift in the each pattern. A second and final shot captures these last patterns. The actual grating displacement and the phase shift can be determined according to the method proposed by Kreis before applying proper phase-shifting techniques to finally calculate the phase difference distribution between windows. Related simulations and experimental results are given. 相似文献
105.
Nadia Kapernaum David M. Walba Prof. Dr. Eva Korblova Dr. Chenhui Zhu Chris Jones Yongqian Shen Noel A. Clark Prof. Frank Giesselmann Prof. Dr. 《Chemphyschem》2009,10(6):890-892
W415 is a chiral smectic compound with a remarkably weak temperature dependence of its giant electroclinic effect in the liquid crystalline smectic A* phase. Furthermore it possesses a high spontaneous polarization in the smectic C* phase. The origin of this striking electroclinic effect is the co‐occurrence of a de Vries‐type ordering with a weak first‐order tilting transition (see the synchroton X‐ray scattering profiles).
106.
Modeling of retention of adrenoreceptor agonists and antagonists on polar stationary phases in hydrophilic interaction chromatography: a review 总被引:1,自引:0,他引:1
Retention prediction models for reversed-phase liquid chromatography (RPLC) have been extensively studied owing to the fact
that RPLC remains the most widely used chromatographic technique especially in the field of pharmaceutical and biomedical
analyses. However, RPLC is not always the method of choice for the analysis of some compounds that have high polarity. Hydrophilic
interaction chromatography (HILIC) has been gaining interest in the last few years as an alternative option to RPLC for the
analysis of polar and hydrophilic analytes. HILIC is a variant of normal-phase liquid chromatography, but utilizes water in
a water-miscible organic solvent as the eluent in conjunction with a hydrophilic stationary phase. The present review aims
to summarize recent contributions on the development of retention prediction models for a group of basic analytes, namely,
the adrenoreceptor agonists and antagonists, on different polar stationary phases. The use of multiple linear regression and
artificial neural networks in model building is highlighted. 相似文献
107.
Zhen-Dan Shi Omid Motabar Ehud Goldin Ke Liu Noel Southall Ellen Sidransky Christopher P. Austin Gary L. Griffiths Wei Zheng 《Analytical and bioanalytical chemistry》2009,394(7):1903-1909
Alpha-galactosidase A hydrolyzes the terminal alpha-galactosyl moieties from glycolipids and glycoproteins in lysosomes. Mutations
in α-galactosidase cause lysosomal accumulation of the glycosphingolipid, globotriaosylceramide, which leads to Fabry disease.
Small-molecule chaperones that bind to mutant enzyme proteins and correct their misfolding and mistrafficking have emerged
as a potential therapy for Fabry disease. We have synthesized a red fluorogenic substrate, resorufinyl α-d-galactopyranoside, for a new α-galactosidase enzyme assay. This assay can be measured continuously at lower pH values, without
the addition of a stop solution, due to the relatively low pK
a of resorufin (~6). In addition, the assay emits red fluorescence, which can significantly reduce interferences due to compound
fluorescence and dust/lint as compared to blue fluorescence. Therefore, this new red fluorogenic substrate and the resulting
enzyme assay can be used in high-throughput screening to identify small-molecule chaperones for Fabry disease.
Zhen-Dan Shi and Omid Motabar contributed equally to this work 相似文献
108.
A Th(IV) compound, [Th(TFSI)4(HTFSI)].2H2O [where TFSI = N(SO2CF3)2], has been synthesized and characterized using elemental analysis, thermogravimetric analysis, and vibrational spectroscopy. The analysis suggests that the TFSI anion coordinates to the metal center via the sulfonyl oxygens as well as provides evidence for the coordination of HTFSI. The voltammetric behavior of this compound has been studied in the room-temperature ionic liquid [Me3NnBu][TFSI], and results show that Th(IV) is reduced to Th(0) in this ionic liquid in a single reduction step. Analysis of cyclic voltammograms shows that an insoluble product is being formed at the electrode surface, which is attributed to the formation of ThO2 by reaction with water. The E0 value for the reduction of Th(IV) to Th(0) has been determined to be -2.20 V (vs Fc+/Fc; -1.80 V vs SHE). A comparison of this E0 value with those obtained for Th(IV) reduction in a LiCl-KCl eutectic (400 degrees C), water, and nonaqueous solvents shows that the reduction in [Me3NnBu][TFSI] is easier to accomplish than that in these other solvents. 相似文献
109.
Solomon GC Gagliardi A Pecchia A Frauenheim T Di Carlo A Reimers JR Hush NS 《The Journal of chemical physics》2006,124(9):94704
We present results for a simulated inelastic electron-tunneling spectra (IETS) from calculations using the "gDFTB" code. The geometric and electronic structure is obtained from calculations using a local-basis density-functional scheme, and a nonequilibrium Green's function formalism is employed to deal with the transport aspects of the problem. The calculated spectrum of octanedithiol on gold(111) shows good agreement with experimental results and suggests further details in the assignment of such spectra. We show that some low-energy peaks, unassigned in the experimental spectrum, occur in a region where a number of molecular modes are predicted to be active, suggesting that these modes are the cause of the peaks rather than a matrix signal, as previously postulated. The simulations also reveal the qualitative nature of the processes dominating IETS. It is highly sensitive only to the vibrational motions that occur in the regions of the molecule where there is electron density in the low-voltage conduction channel. This result is illustrated with an examination of the predicted variation of IETS with binding site and alkane chain length. 相似文献
110.
Thalictrum is an important plant genus that is widely used in traditional medicine. In this review considerable attention has been given to triterpenoid saponins in connection with their specific distribution in the Thalictrum genus and with their biological activity. All other non-alkaloid compounds isolated from the Thalictrum genus are also reviewed; these metabolites are discussed in relation to their structural features and to their role in the plants. 相似文献