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241.
M. Kilian 《Proceedings of the American Mathematical Society》2004,132(10):3075-3082
We use the generalised Weierstraßrepresentation of Dorfmeister, Pedit and Wu to obtain the associated family of Delaunay surfaces and derive a formula for the neck size of the surface in terms of the entries of the holomorphic potential.
242.
S. Abdel-Samad J. Bojowald A. Budzanowski A. Chatterjee J. Ernst D. Frekers P. Hawranek J. Ilieva L. Jarczyk K. Kilian S. Kliczewski W. Klimala D. Kolev M. Kravcíková T. Kutsarova J. Lieb H. Machner A. Magiera G. Martinská H. Nann L. Pentchev D. Protic P. von Rossen B. J. Roy R. Siudak A. Strzalkowski R. Tsenov M. Ulicný J. Urbán K. Zwoll 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):367-370
243.
A detailed investigation of the multilayer growth of PTCDA on Ag(1 1 1) by high resolution LEED (SPA-LEED) is reported. The first two monolayers are closed and exhibit a structure, which is commensurate with respect to the underlying Ag(1 1 1) surface. The lattice parameters are close to those of the (1 0 2) plane of the β bulk phase of PTCDA, with deviations ?2%. The vertical stacking of the second layer with respect to the first monolayer (observed at 300 K) corresponds to that in the β bulk phase of PTCDA. At high growth temperatures (400 K), Stranski-Krastanov growth occurs from the third monolayer onward, and PTCDA clusters, preferentially with few well defined facets, grow. The structure of the clusters is that of the thermodynamically more stable α bulk phase of PTCDA. Contrary, at low growth temperatures (200 K), the growth proceeds in the Frank van der Merve mode, with several open layers. From slope selection there is evidence for an Ehrlich-Schwoebel barrier. The lateral packing of the PTCDA grown at low temperatures corresponds within error to that of the β bulk phase. The low temperature structure and morphology is meta-stable. Short annealing at 300 K flattens the PTCDA film, and prolonged annealing at 400 K causes the film to adapt the structure and morphology obtained directly at 400 K growth temperature. Presumably, the formation of layers with a β-phase-like lattice at low temperature is due to the better fit of the β phase, compared to the α phase lattice, to the underlying commensurate monolayer. However, at high growth temperatures, the thermodynamically more stable α phase grows, reducing the area of lattice misfit to the underlying commensurate first two layers by formation of clusters. 相似文献
244.
ABSTRACT One-dimensional and two-dimensional spectral data are presented for the N -terminal glycooctapeptide derived from the transmembrane glycoprotein, glycophorin AM. Two-dimensional homonuclear Hartmann-Hahn spectroscopy (2D-HOHAHA) and two-dimensional rotating frame nuclear Overhauser enhancement spectroscopy (2D-ROESY) were used to assign many of the resonances present in the spectra, with specific emphasis placed upon the oligosaccharide units. Not only were intra residue NOE's detected, but also inter residue NOE's involving two linked carbohydrates [β-Gal(1-->3)α-GalNAc] and also between the α-GalNac-->Thr linkage pair (between GalNAc H-1 and Thr Hβ) indicating restricted motion about this glycosidic bond. Moreover, the H-1/H-2 cross-peaks in the 2D-ROESY spectra appear to be well resolved indicating some chemical shift differences for H-1 and H-2 of the three linkage GalNAc residues found in this glycooctapeptide. 相似文献
245.
Kilian R. A. Schneider Avinash Chettri Houston D. Cole Dr. Katharina Reglinski Jannik Brückmann John A. Roque III Dr. Anne Stumper Dr. Djawed Nauroozi Dr. Sylvia Schmid Dr. Christoffer B. Lagerholm Prof. Dr. Sven Rau Prof. Dr. Peter Bäuerle Prof. Dr. Christian Eggeling Dr. Colin G. Cameron Prof. Dr. Sherri A. McFarland Prof. Dr. Benjamin Dietzek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(65):14844-14851
This contribution describes the excited-state properties of an Osmium-complex when taken up into human cells. The complex 1 [Os(bpy)2(IP-4T)](PF6)2 with bpy=2,2′-bipyridine and IP-4T=2-{5′-[3′,4′-diethyl-(2,2′-bithien-5-yl)]-3,4-diethyl-2,2′-bithiophene}imidazo[4,5-f][1,10]phenanthroline) can be discussed as a candidate for photodynamic therapy in the biological red/NIR window. The complex is taken up by MCF7 cells and localizes rather homogeneously within in the cytoplasm. To detail the sub-ns photophysics of 1 , comparative transient absorption measurements were carried out in different solvents to derive a model of the photoinduced processes. Key to rationalize the excited-state relaxation is a long-lived 3ILCT state associated with the oligothiophene chain. This model was then tested with the complex internalized into MCF7 cells, since the intracellular environment has long been suspected to take big influence on the excited state properties. In our study of 1 in cells, we were able to show that, though the overall model remained the same, the excited-state dynamics are affected strongly by the intracellular environment. Our study represents the first in depth correlation towards ex-vivo and in vivo ultrafast spectroscopy for a possible photodrug. 相似文献
246.
D. Kilian D. Knawby M. A. Athanassopoulou S. T. Trzaska T. M. Swager S. Wrobel 《Liquid crystals》2013,40(4):509-521
Two liquid crystalline vanadyl complexes have been studied by frequency domain dielectric spectroscopy over the range 10 mHz to 13 MHz. The materials exhibit two or three columnar phases denoted Colro, Colrd, and Colhd that were identified by X-ray diffraction. In the higher temperature Colrd phase, a relaxation process in the kHz range is observed that is attributed to the reorientation about the molecular short axis. A pronounced dielectric relaxation process shows up in the low temperature Colro phase at hertz and sub-hertz frequencies. This slow relaxation is assigned to reorientation of the molecular dipoles within the polar linear chains, which are aligned along the column's axis. Triangular wave switching studies at low frequency reveal processes inside the Colro phase which are most probably due to ionic/charges relaxations but a ferroelectric switching for an achiral discotic system cannot be ruled out completely. Below the Colro phase there is an orientationally disordered crystalline Crx phase with disordered side chain dipoles. A dielectric relaxation process connected with the intramolecular relaxation of the alkoxy side chains, similar to the beta-process of polymers, has been found in the lower temperature Crx phase. 相似文献
247.
The preconcentration of some divalent metal ions by complexation with carboxyphenylporphyrin (TCPP) and retention on conventional anion-exchange resins and a non-ionic sorbent was examined. Two different procedures--ligand in solution or immobilised on the solid sorbents--were evaluated as a function of pH. The selectivity order for metal ions on the TCPP-loaded resin Amberlite IRA-904 was established as: Pb(II)>Ni(II)>Cu(II)>Cd(II)>Mg(II). 相似文献
248.
Friederike Teichert Richard D. Verschoyle Peter Greaves James F. Thorpe J. Kilian Mellon William P. Steward Peter B. Farmer Andreas J. Gescher Rajinder Singh 《Rapid communications in mass spectrometry : RCM》2009,23(2):258-266
Urinary 8‐oxo‐7,8‐dihydro‐2′‐deoxyguanosine (8‐oxodG) represents a non‐invasive biomarker for oxidative stress and may be useful for monitoring chemotherapeutic and chemopreventive interventions associated with cancer‐related alterations in oxidative stress. We describe the development and validation of two separate liquid chromatography/tandem mass spectrometry (LC/MS/MS) selected reaction monitoring (SRM) methods for the determination of 8‐oxodG and creatinine in both murine and human urine using stable isotope labelled internal standards. Levels of 8‐oxodG were normalised to creatinine. The LC/MS/MS methods were applied to two chemoprevention studies utilising tea polyphenols in humans and TRAMP (TRansgenic Adenocarcinoma of the Mouse Prostate) mice. Patients with benign prostatic hyperplasia received 1 g/day of green tea polyphenols (GTP), 1 g/day of black tea theaflavins (BTT) or no treatment for 4 weeks. TRAMP mice received GTP (0.05% in drinking water) for 4 or 25 weeks. Prostate pathology in TRAMP mice was not affected by GTP. Levels of 8‐oxodG were not altered by tea polyphenols in either mice or humans. In TRAMP mice, urinary 8‐oxodG levels were elevated with increasing age (p < 0.0001) but not changed by the presence of prostate tumours. In conclusion, the LC/MS/MS SRM methods described here are ideally suited for the accurate determination of 8‐oxodG and creatinine in urine samples from both clinical and pre‐clinical studies. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
249.
David T. Williamson Lars Kilian Timothy E. Long 《Journal of polymer science. Part A, Polymer chemistry》2005,43(6):1216-1227
The living synthesis of poly(1,3‐cyclohexadiene) was performed with an initiator adduct that was synthesized from a 1:2 (mol/mol) mixture of N,N,N′,N′‐tetramethylethylenediamine (TMEDA) and n‐butyllithium. This initiator, which was preformed at 65 °C, facilitated the synthesis of high‐molecular‐weight poly(1,3‐cyclohexadiene) (number‐average molecular weight = 50,000 g/mol) with a narrow molecular weight distribution (weight‐average molecular weight/number‐average molecular weight = 1.12). A plot of the kinetic chain length versus the time indicated that termination was minimized and chain transfer to the monomer was eliminated when a preformed initiator adduct was used. Chain transfer was determined to occur when the initiator was generated in situ. The polymerization was highly sensitive to both the temperature and the choice of tertiary diamine. The use of the bulky tertiary diamines sparteine and dipiperidinoethane resulted in poor polymerization control and reduced polymerization rates (7.0 × 10−5 s−1) in comparison with TMEDA‐mediated polymerizations (1.5 × 10−4 s−1). A series of poly(1,3‐cyclohexadiene‐block‐isoprene) diblock copolymers were synthesized to determine the molar crossover efficiency of the polymerization. Polymerizations performed at 25 °C exhibited improved molar crossover efficiencies (93%) versus polymerizations performed at 40 °C (80%). The improved crossover efficiency was attributed to the reduction of termination events at reduced polymerization temperatures. The microstructure of these polymers was determined with 1H NMR spectroscopy, and the relationship between the molecular weight and glass‐transition temperature at an infinite molecular weight was determined for polymers containing 70% 1,2‐addition (150 °C) and 80% 1,4‐addition (138 °C). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1216–1227, 2005 相似文献
250.
The structures of nanodefect ensembles formed on the surfaces of copper, gold, and molybdenum under a load have been investigated. The properties of the defect ensembles are described in the framework of the reversible aggregation model. The size distribution of nanodefects is thermodynamically determined by the maximum “entropy of their mixing” with atoms of the crystal lattice. The entropy of mixing reaches a maximum value at a small concentration of defects due to a considerable difference in the sizes of defects and atoms. This concentration agrees closely with the experimental data. The reduced size distribution of defects is universal. 相似文献