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81.
82.
Harding DJ Gruene P Haertelt M Meijer G Fielicke A Hamilton SM Hopkins WS Mackenzie SR Neville SP Walsh TR 《The Journal of chemical physics》2010,133(21):214304
The geometric structures of small cationic rhodium clusters Rh(n)(+) (n = 6-12) are investigated by comparison of experimental far-infrared multiple photon dissociation spectra with spectra calculated using density functional theory. The clusters are found to favor structures based on octahedral and tetrahedral motifs for most of the sizes considered, in contrast to previous theoretical predictions that rhodium clusters should favor cubic motifs. Our findings highlight the need for further development of theoretical and computational methods to treat these high-spin transition metal clusters. 相似文献
83.
Falk Bernsmann Dr. Ovidiu Ersen Dr. Jean‐Claude Voegel Edward Jan Prof. Nicholas A. Kotov Prof. Vincent Ball 《Chemphyschem》2010,11(15):3299-3305
Films formed by oxidation of dopamine are of interest for functionalisation of solid–liquid interfaces owing to their versatility. However, the ability to modulate the properties of such films, for example, permeability to ionic species and the absorption coefficient, is urgently needed. Indeed, melanin films produced by oxidation of dopamine absorb strongly over the whole UV/Vis part of the electromagnetic spectrum and are impermeable to anions even for a film thickness as low as a few nanometers. Herein we combine oxidation of dopamine to produce a solution containing dopamine–melanin particles and their alternating deposition with poly(diallyldimethylammonium chloride) to produce films which have nearly the same morphology as pure dopamine–melanin films but are less compact, more transparent and more permeable to ferrocyanide anions. 相似文献
84.
Jarrod J. M. Amoore Dr. Suzanne M. Neville Dr. Boujemaa Moubaraki Dr. Simon S. Iremonger Dr. Keith S. Murray Prof. Jean‐François Létard Dr. Cameron J. Kepert Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(6):1973-1982
We previously reported the dinuclear material [FeII2(ddpp)2(NCS)4] ? 4 CH2Cl2 ( 1? 4 CH2Cl2; ddpp=2,5‐di(2′,2′′‐dipyridylamino)pyridine) and its partially desolvated analogue ( 1? CH2Cl2), which undergo two‐ and one‐step spin‐crossover (SCO) transitions, respectively. Here, we manipulate the type and degree of solvation in this system and find that either a one‐ or two‐step spin transition can be specifically targeted. The chloroform clathrate 1? 4 CHCl3 undergoes a relatively abrupt one‐step SCO, in which the two equivalent FeII sites within the dinuclear molecule crossover simultaneously. Partial desolvation of 1? 4 CHCl3 to form 1? 3 CHCl3 and 1? CHCl3 occurs through single‐crystal‐to‐single‐crystal processes (monoclinic C2/c to P21/n to P21/n) in which the two equivalent FeII sites become inequivalent sites within the dinuclear molecule of each phase. Both 1? 3 CHCl3 and 1? CHCl3 undergo one‐step spin transitions, with the former having a significantly higher SCO temperature than 1? 4 CHCl3 and the latter, and each has a broader SCO transition than 1? 4 CHCl3, attributable to the overlap of two SCO steps in each case. Further magnetic manipulation can be carried out on these materials through reversibly resolvating the partially desolvated material with chloroform to produce the original one‐step SCO, or with dichloromethane to produce a two‐step SCO reminiscent of that seen for 1? 4 CH2Cl2. Furthermore, we investigate the light‐induced excited spin state trapping (LIESST) effect on 1? 4 CH2Cl2 and 1? CH2Cl2 and observe partial LIESST activity for the former and no activity for the latter. 相似文献
85.
R. J. Ball G. C. Allen G. Starrs W. J. McCarter 《Applied Physics A: Materials Science & Processing》2011,105(3):739-751
The conduction and dielectric behaviour of two different grades of natural hydraulic lime is presented over the frequency
range 1 Hz–1 MHz, with measurements taken over the initial six months after gauging with water. Samples containing embedded
electrodes were exposed to both a natural atmosphere (20°C and 65% relative humidity) and a natural atmosphere with a carbon
dioxide concentration maintained at 400 ppm which was used to accelerate the carbonation process. A decrease in relative dielectric
permittivity and rise in conductivity, with increasing frequency, was observed at all stages over the time-scale presented.
When plotted in the complex plane, the impedance featured a bulk response comprising two depressed semicircles and a low frequency
spur, the latter being associated with the electrode/sample interface. The complex impedance plot, together with the application
of an equivalent circuit model, indicated a dual arc feature with carbonation and hydration contributing to bulk impedance
response. This study demonstrates the applicability of electrical property measurements to monitor the combined processes
of hydration and carbonation in this group of materials. 相似文献
86.
A. Gorelov J.A. Behr D. Melconian M. Trinczek P. Dubé O. Häusser U. Giesen K.P. Jackson T. Swanson J.M. D'Auria M. Dombsky G. Ball L. Buchmann B. Jennings J. Dilling J. Schmid D. Ashery J. Deutsch W.P. Alford D. Asgeirsson W. Wong B. Lee 《Hyperfine Interactions》2000,127(1-4):373-380
Laser trapping and cooling techniques are now being applied to the study of nuclear β-decay at several labs. A magneto-optical
trap (MOT) provides a localized source of atoms suspended in space, so the low-energy recoiling nuclei can freely escape and
be detected in coincidence with the β. This allows reconstruction of the neutrino momentum, and the deduction of the β-v correlation in a more direct fashion than previously possible. In addition, the nuclei can be polarized by atomic techniques,
opening a new class of spin correlation measurements to test the degree to which parity is maximally violated in the weak
interaction. Our present experiment has detected several hundred thousand recoil-β+ coincidences from the 0+ → 0+ pure Fermi decay of 38mK, produced at the on-line isotope separators TISOL and ISAC at TRIUMF. Our goal is to set constraints on non-Standard Model
scalar bosons competitive with high-energy colliders and more conventional β-v correlation experiments.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
87.
Alexander N. Zaykov Brian V. Popp Dr. Zachary T. Ball Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(22):6651-6659
The use of carboxylate side chains to induce peptide helicity upon binding to dirhodium centers is examined through experimental and computational approaches. Dirhodium binding efficiently stabilizes α helicity or induces α helicity in otherwise unstructured peptides for peptides that contain carboxylate side chains with i, i+4 spacing. Helix induction is furthermore possible for sequences with i, i+3 carboxylate spacing, though in this case the length of the side chains is crucial: ligating to longer glutamate side chains is strongly helix inducing, whereas ligating the shorter aspartate side chains destabilizes the helical structure. Further studies demonstrate that a dirhodium metallopeptide complex persists for hours in cellular media and exhibits low toxicity toward mammalian cells, enabling exploitation of these metallopeptides for biological applications. 相似文献
88.
89.
90.
This paper contains a generalization of results from [BG1]. Here we classify the set of pairs of shift invariant subspaces, find the invariants and simplest representative of each class. The results are applied to analyse different types of LU factorizations with a middle factor. 相似文献