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121.
Larry Sadwick 《Journal of Electronic Materials》1990,19(7):637-650
The capacitance-voltage (C-V) technique is one of the most powerful and direct methods to investigate interface traps in metal-insulator-semiconductor
(MIS or MOS) related devices. As the C-V technique is of such fundamental importance in detecting and monitoring process related
defects the systematic measurement concerns, misinterpretations and limitations associated with the equipment used to implement
this technique must be fully understood and characterized. This study reports the results of a detailed comparison of both
the (raw) measured C-V curve and the (analyzed) interface trap density versus energy data obtained using commercially available
quasistatic meters, specifically the Hewlett-Packard (HP) model 4140B quasistatic/dc picoammeter and the Keithley model 595
quasistatic meter. 相似文献
122.
Larry Guth 《Inventiones Mathematicae》2008,172(3):477-489
If P and P
′ are symplectic polydisks of radii R
1≤...≤R
n
and R
1
′≤...≤R
n
′, respectively, then we prove that P symplectically embeds in P
′ provided that C(n)R
1≤R
1
′ and C(n)R
1...R
n
≤R
1
′...R
n
′. Up to a constant factor, these conditions are optimal. 相似文献
123.
Liquid-liquid extraction employing supercritical carbon dioxide has been developed for removal of polar materials from water. 相似文献
124.
Summary. Macro-elements of arbitrary smoothness are constructed on Clough-Tocher triangle splits. These elements can be used for solving
boundary-value problems or for interpolation of Hermite data, and are shown to be optimal with respect to spline degree. We
conjecture they are also optimal with respect to the number of degrees of freedom. The construction provides local bases for
certain superspline spaces defined over Clough-Tocher refinements of arbitrary triangulations. These bases are shown to be
stable as a function of the smallest angle in the triangulation, which in turn implies that the associated spline spaces have
optimal order approximation power.
Received November 18, 1999 / Published online October 16, 2000 相似文献
125.
Larry Bates 《manuscripta mathematica》1990,66(1):109-111
Abstract A proof of the rigidity of closed symplectic polydiscs is given. 相似文献
126.
The acute toxicity for tri-n-butyltin taurocholate (TBT-TA), a newly synthesized organotin steroid, was determined using Long Evans rats. The organotin compound was suspended in corn oil and administered by gavage using standard techniques. The TBT-TA exhibited a taurocholic acid toxicity at 24 h and a tributyltin toxicity at three days. The LD50 values were 611 and 384 mg kg?1 respectively. The dead rats exhibited distended stomachs, enlarged cecums, and lesions in the gastrointestinal tract. The toxicity is similar to that observed with other trialkyltin compounds. 相似文献
127.
Juraj Černák Juraj Kuchár Monika Stolárová Marcela Kajňaková Martin Vavra Ivan Potočňák Larry R. Falvello Milagros Tomás 《Transition Metal Chemistry》2010,35(6):737-744
From the systems Cu(II)–cyclam–[M(CN)4]2? (cyclam = 1,4,8,11-tetraazacyclotetradecane; M = Ni, Pd, Pt), three cyanidocomplexes Cu(cyclam)M(CN)4 [M = Ni (1), Pd (2), Pt (3)] were isolated and characterized by chemical analysis, IR and UV–VIS spectroscopy. The three compounds are isostructural, and their crystal structures are formed by quasi-linear chains exhibiting [–Cu(cyclam)–μ–NC–M(CN)2–μ–CN–]n composition. The Cu(II) atoms reside on centres of symmetry and are coordinated in the form of an elongated octahedron with mean equatorial Cu–N bonds of 2.015(12), 2.017(13) and 2.011(11) Å in (1), (2) and (3), respectively, and weakly N-bonded bridging cyanido ligands in the axial positions [2.5321(9) Å in (1), 2.518(2) Å in (2) and 2.549(3) Å in (3)]. Hydrogen bonds of the N–H···Ncyanido···H–N type link neighbouring chains, and a topologically square network of paramagnetic Cu(II) atoms is formed. The magnetic susceptibilities of all three complexes follow the Curie-Weiss law with a weak antiferromagnetic exchange coupling below 5 K. 相似文献
128.
Cannon JS Kirsch SF Overman LE Sneddon HF 《Journal of the American Chemical Society》2010,132(43):15192-15203
The catalytic enantioselective S(N)2' displacement of (Z)-allylic trichloroacetimidates catalyzed by the palladium(II) complex [COP-OAc](2) is a broadly useful method for the asymmetric synthesis of chiral branched allylic esters. A variety of experiments aimed at elucidating the nature of the catalytic mechanism and its rate- and enantiodetermining steps are reported. Key findings include the following: (a) the demonstration that a variety of bridged-dipalladium complexes are present and constitute resting states of the COP catalyst (however, monomeric palladium(II) complexes are likely involved in the catalytic cycle); (b) labeling experiments establishing that the reaction proceeds in an overall antarafacial fashion; (c) secondary deuterium kinetic isotope effects that suggest substantial rehybridization at both C1 and C3 in the rate-limiting step; and (d) DFT computational studies (B3-LYP/def2-TZVP) that provide evidence for bidentate substrate-bound intermediates and an anti-oxypalladation/syn-deoxypalladation pathway. These results are consistent with a novel mechanism in which chelation of the imidate nitrogen to form a cationic palladium(II) intermediate activates the alkene for attack by external carboxylate in the enantiodetermining step. Computational modeling of the transition-state structure for the acyloxy palladation step provides a model for enantioinduction. 相似文献
129.
Berwyck L. J. Poad Huong T. Pham Michael C. Thomas Jessica R. Nealon J. Larry Campbell Todd W. Mitchell Stephen J. Blanksby 《Journal of the American Society for Mass Spectrometry》2010,21(12):1989-1999
Ozone-induced dissociation (OzID) exploits the gas-phase reaction between mass-selected lipid ions and ozone vapor to determine
the position(s) of unsaturation. In this contribution, we describe the modification of a tandem linear ion-trap mass spectrometer
specifically for OzID analyses wherein ozone vapor is supplied to the collision cell. This instrumental configuration provides
spatial separation between mass-selection, the ozonolysis reaction, and mass-analysis steps in the OzID process and thus delivers
significant enhancements in speed and sensitivity (ca. 30-fold). These improvements allow spectra revealing the double-bond
position(s) within unsaturated lipids to be acquired within 1 s: significantly enhancing the utility of OzID in high-throughput
lipidomic protocols. The stable ozone concentration afforded by this modified instrument also allows direct comparison of
relative reactivity of isomeric lipids and reveals reactivity trends related to (1) double-bond position, (2) substitution
position on the glycerol backbone, and (3) stereochemistry. For cis- and trans-isomers, differences were also observed in the branching ratio of product ions arising from the gas-phase ozonolysis reaction,
suggesting that relative ion abundances could be exploited as markers for double-bond geometry. Additional activation energy
applied to mass-selected lipid ions during injection into the collision cell (with ozone present) was found to yield spectra
containing both OzID and classical-CID fragment ions. This combination CID-OzID acquisition on an ostensibly simple monounsaturated
phosphatidylcholine within a cow brain lipid extract provided evidence for up to four structurally distinct phospholipids
differing in both double-bond position and sn-substitution. 相似文献
130.
Campbell JL 《Rapid communications in mass spectrometry : RCM》2010,24(24):3527-3530
Atmospheric pressure ionization (API) sources have the ability to serve as dynamic 'reaction vessels' and this capability has been rapidly evolving over the past few years. With API sources, many different reagents and source conditions can be rapidly explored with minimal carryover or contamination of the mass spectrometer. While most API applications involve the simple protonation/deprotonation of analyte molecules, a great deal of flexibility and utility is available in almost any API source, provided the reagents and ionization conditions are judiciously selected. Here, the generation of a unique and useful class of reagent ions at atmospheric pressure is demonstrated for the first time. Within the AP gas-phase environment of a dual inlet ion source, the gas-phase synthesis of substituted N-phenylpyridinium cations is demonstrated by establishing conditions favorable to the nucleophilic substitution reaction required for their formation. The flexibility of this API source as a reaction vessel is also demonstrated. 相似文献