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181.
R.B. King 《Journal of mathematical chemistry》1998,23(1-2):197-227
Elemental carbon has recently been shown to form molecular polyhedral allotropes known as fullerenes in addition to the familiar
graphite and diamond known since antiquity. Such fullerenes contain polyhedral carbon cages in which all vertices have degree
3 and all faces are either pentagons or hexagons. All known fullerenes are found to satisfy the isolated pentagon rule (IPR)
in which all pentagonal faces are completely surrounded by hexagons so that no two pentagonal faces share an edge. The smallest
fullerene structures satisfying the IPR are the known truncated icosahedral C60 of I
h
symmetry and ellipsoidal C70 of D
5h
symmetry. The multiple IPR isomers of families of larger fullerenes such as C76, C78, C82 and C84 can be classified into families related by the so-called pyracylene transformation based on the motion of two carbon atoms
in a pyracylene unit containing two linked pentagons separated by two hexagons. Larger fullerenes with 3ν vertices can be
generated from smaller fullerenes with ν vertices through a so‐called leapfrog transformation consisting of omnicapping followed
by dualization. The energy levels of the bonding molecular orbitals of fullerenes having icosahedral symmetry and 60n
2 carbon atoms can be approximated by spherical harmonics. If fullerenes are regarded as constructed from carbon networks of
positive curvature, the corresponding carbon allotropes constructed from carbon networks of negative curvature are the polymeric
schwarzites. The negative curvature in schwarzites is introduced through heptagons or octagons of carbon atoms and the schwarzites
are constructed by placing such carbon networks on minimal surfaces with negative Gaussian curvature, particularly the so-called
P and D surfaces with local cubic symmetry. The smallest unit cell of a viable schwarzite structure having only hexagons and
heptagons contains 168 carbon atoms and is constructed by applying a leapfrog transformation to a genus 3 figure containing
24 heptagons and 56 vertices described by the German mathematician Klein in the 19th century analogous to the construction
of the C60 fullerene truncated icosahedron by applying a leapfrog transformation to the regular dodecahedron. Although this C168 schwarzite unit cell has local O
h
point group symmetry based on the cubic lattice of the D or P surface, its larger permutational symmetry group is the PSL(2,7)
group of order 168 analogous to the icosahedral pure rotation group, I, of order 60 of the C60 fullerene considered as the isomorphous PSL(2,5) group. The schwarzites, which are still unknown experimentally, are predicted
to be unusually low density forms of elemental carbon because of the pores generated by the infinite periodicity in three
dimensions of the underlying minimal surfaces.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
182.
Kristin Geddes Gary Adamson Neal Dube Susan Crathern Richard C. King 《Rapid communications in mass spectrometry : RCM》2009,23(9):1303-1312
This paper describes an automated workflow for the determination of selected reaction monitoring (SRM) transitions and optimum mass spectrometric (MS) instrument parameters. The approach uses a Nanomate from Advion Biosciences for automated infusion of small amounts of sample in combination with Automaton optimization software from Sciex. The results are stored in the Analyst software Compound Database for automated acquisition method building. Comparisons are presented between the more traditional optimization methods of manual flow injection optimization, Autotune infusion optimization, Automaton flow injection optimization and the Nanomate–Automaton optimization approach. Data is also presented to show that acquisition methods developed on the Sciex model API3000 instrument can be effectively transferred to the Sceix API4000 and API5000 model instruments. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
183.
Anthony D'Aléo Jide Xu King Do Gilles Muller Kenneth N. Raymond 《Helvetica chimica acta》2009,92(11):2439-2460
The synthesis of the cyclen derivative H4 L 1 ?2 HBr containing four 2‐hydroxybenzamide groups is described. The spectroscopic properties of the LnIII conplexes of L 1 (Ln=Gd, Tb, Yb, and Eu) reveal changes of the UV/VIS‐absorption, circular‐dichroism‐absorption, luminescence, and circularly polarized luminescence spectra. It is shown that at least two metal‐complex species are present in solution, whose relative amounts are pH dependent. At pH>8.0, an intense long‐lived emission is observed (for [Tb L 1 ] and [Yb L 1 ]), while at pH<8.0, a weaker, shorter‐lived species predominates. Unconventional LnIII emitters (Pr, Nd, Sm, Dy, and Tm) were sensitized in basic solution, both in the VIS and in the near‐IR, to measure the emission of these ions. 相似文献
184.
R Bonfiglio RC King TV Olah K Merkle 《Rapid communications in mass spectrometry : RCM》1999,13(12):1175-1185
A post-column infusion system was developed in order to analyze suppression of electrospray ionization (ESI) tandem mass spectrometry response in the presence of endogenous plasma interferences. By enabling direct detection of these interfering components, this experimental system was used to analyze the ability of several common extraction procedures to remove endogenous plasma components that cause changes in the ESI response of model drug substances. Methyl-t-butyl ether (MTBE) liquid-liquid, Oasis and Empore solid-phase, and acetonitrile (ACN) protein precipitation sample preparation methods were tested using the post-column infusion system. In all cases, ACN protein precipitation samples showed the greatest amount of ESI response suppression while liquid-liquid extracts demonstrated the least. In addition, the three test compounds, phenacetin, caffeine, and a representative Merck compound, demonstrated that ESI response suppression is compound dependent. Suppression was greatest with caffeine, the most polar analyte, and the smallest for the Merck compound, the least polar analyte. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
185.
186.
Jonathan King 《Israel Journal of Mathematics》1987,59(3):377-380
If transformationR is ap-point extension of a mixingT thenp · rank(T) lower bounds the rank ofR.
The author was partially supported by NSF grant DMS8501519. 相似文献
187.
Jian‐Ging Chen Ken‐Yen Liu Chia‐Yuan Chen Chia‐Yu Lin Kuan‐Chieh Huang Yi‐Hsuan Lai Chun‐Guey Wu King‐Fu Lin Kuo‐Chuan Ho 《Journal of polymer science. Part A, Polymer chemistry》2010,48(22):4950-4957
This study reports the characteristics of gel‐type dye‐sensitized solar cells (DSSCs), fabricated with gel‐type electrolyte containing poly‐1,1′‐(methylenedi‐4,1‐phenylene)bismaleimide (PBMI), or poly‐1,1′‐(3,3′‐dimethyl‐1,1′‐biphenyl‐4,4′‐diyl)bismaleimide (PDBBMI), or poly‐N,N′‐(4‐methyl‐1,3‐phenylene)bismaleimide (PMPBMI), prepared by in situ polymerization of the corresponding monomer without an initiator at 30 °C. Incorporating 0.3 wt % content of exfoliated alkyl‐modified nanomica (EAMNM) into PBMI‐gelled electrolyte leads to higher short‐circuit current density (Jsc = 17.14 mA cm?2) and efficiency (η = 7.02%) than that of neat PBMI‐gel electrolyte (Jsc = 15.32 mA cm?2, η = 6.41%). Incorporating 0.3 wt % EAMNM into PBMI‐gelled electrolyte results in remarkably stable device performance under continuous light soaking under one sun (100 mW cm?2) at 55 °C. The efficiency of DSSCs based on PBMI/0.3 wt % EAMNM‐gelled electrolyte drops by only 1.7% (η = 6.93%) after 500 h of continuous light soaking. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
188.
Hongji Liu Byung-Yun Cho Richard Strong Ira S. Krull Steven Cohen King C. Chan Haleem J. Issaq 《Analytica chimica acta》1999,400(1-3):181-209
Peptides and small proteins, of limited molecular weight (MW) can be derivatized with a 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (6-AQC) reagent, leading to a single capillary zone electrophoresis (CZE) peak, suggestive of a completely tagged product. The number of tags per molecule was demonstrated by matrix assisted, laser desorption, time-of-flight mass spectrometry (MALDI-TOFMS) studies. In CZE, these species have greatly improved plate count and peak shape, improved (lowered) detectabilities, and in general, improved identification properties in the CZE mode in high performance capillary electrophoresis (HPCE). The formation of what appears to be a single, homogeneously tagged product is a function of how the derivatizations are performed. Once these conditions are optimized, virtually all peptides and small proteins tested (limited MW) can form single, fully tagged products, with the desirable CZE properties. These derivatization approaches thus lead to products that perform and are detected much better in CZE than their precursors (native, untagged peptides). The determined plate counts for these tagged peptides were as high as 6 million plates/m, which was very reproducible, and 59–12,000 times higher than the untagged (native) molecules. The peak symmetry was also improved greatly. The limit of detection (LOD) of some tested 6-AQC tagged peptides were nine to 209 times improved (lower) with ultraviolet (UV) absorption detection, again as compared with that for the native species. The LOD could be further lowered via laser induced fluorescence (LIF) detection in CZE, especially when acetonitrile (ACN) containing buffers were used. 相似文献
189.
King‐Fu Lin Jing‐Yau Shyu 《Journal of polymer science. Part A, Polymer chemistry》2001,39(18):3085-3092
The early cure behavior of 4,4‐dicyanato 1,1‐diphenolethane resin with and without incorporating Cr(acac)3, Co(acac)3, and Cu(acac)2, respectively, as catalysts was investigated by gel permeation chromatography. The curing intermediates were separated by the column elution method and characterized by Fourier transform infrared, 1H, and 3C NMR spectroscopies. The results indicated that the formed dimer in the early cure stage is a straight chain containing a primary amino group. The formed triazine ring in the trimer has a strong catalytic effect on the remaining cyanate groups so that the reactivity of the trimers was significantly increased. The reactivities of the curing intermediates decreased with molecular size until 7‐mer was reached. The initial monomer consumption is described by second‐order‐rate kinetics. In the presence of metal acetylacetonates, the curing reactions may be accelerated, but they did not change the reaction path and preceding sequence of reactivities. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3085–3092, 2001 相似文献
190.
Ling‐Hai Xie Xian‐Yu Deng Lin Chen Shu‐Fen Chen Ran‐Ran Liu Xiao‐Ya Hou King‐Young Wong Qi‐Dan Ling Wei Huang 《Journal of polymer science. Part A, Polymer chemistry》2009,47(20):5221-5229
The combination of π‐stacked with π‐conjugated building blocks offers an essential strategy to construct multifunctional organic semiconductors (MOSs) with the unique optoelectrical properties. Covalent hybrids can efficiently avoid the intrinsic phase‐separation defects in corresponding blend system. In this contribution, poly(vinylcarbazole) tethered with terfluorene, PVK‐TF, as a double‐channeled π‐stacked and π‐conjugated hybrid (SCH), has been constructed via Friedal‐Crafts click postmodification (FCCP). The chemical structure and optoelectrical property were determined by GPC, UV–vis, PL, TGA, DSC, and CV. Its PL spectra in the annealing thin film at N2 atmosphere without low‐energy emission bands centered at the 530 nm indicates that no π‐stacks between carbazole and TF or among TFs dominate the whole condensed phase, which is in agreement with the intrachain T‐shaped π‐pitched motifs in molecular modeling simulation due to steric hindrance effect in complicated diarylfluorenes (CDAFs). A supporting prototype stable deep‐blue PLED was successfully obtained with an Internationale de l'Eclairage (CIE) coordinates of (0.20, 0.10) and a width at half maximum (FWHM) of about 60 nm at high current density of 100 mA/cm2 (35 V). Deep‐blue PVK‐TF is a promising MOS for hole‐transporting and host materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5221–5229, 2009 相似文献