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151.
152.
Pharmacokinetic analysis of blood distribution of intravenously administered 153Gd-labeled Gd(DTPA)2- and 99mTc(DTPA) in rats 总被引:1,自引:1,他引:0
P Wedeking S Eaton D G Covell S Nair M F Tweedle W C Eckelman 《Magnetic resonance imaging》1990,8(5):567-575
Rat plasma distribution data obtained following IV administration of 99mTc(DTPA) alone or after co-administration of 99mTc(DTPA) and 153Gd-labeled Gd(DTPA)2- at 0.001, 0.1, and 1.0 mmol Gd/kg were evaluated using compartmental modeling techniques. A three-compartment open model was found to fit the data significantly better (P less than 0.01) than a two- or four-compartment open model. This model incorporates and links the plasma and urine data and includes a delay to account for the transit time through the kidneys/ureters. The two nonplasma compartments of the model were assumed to be related to rapidly and slowly equilibrating tissues. Tc(DTPA) and Gd(DTPA)2- had nearly identical pharmacokinetic profiles in plasma and the rate constants were essentially the same. No significant dose dependent pharmacokinetic differences were found for the range of Gd(DTPA)2- doses tested. Simulations of the proposed three-compartment model were used to generate concentration-time curves for each of the three compartments. 相似文献
153.
4-Phospho-d-erythronate is an intermediate in the synthesis of pyridoxal 5′-phosphate in some bacteria and an inhibitor of ribose 5-phosphate isomerase. Previous synthetic schemes for the preparation of 4-phospho-d-erythronate required expensive precursors and typically gave low yields. We report a straightforward synthesis of 4-phospho-d-erythronate from the inexpensive precursor d-erythronolactone in five steps with a preparatively useful yield of 22%. 相似文献
154.
Samuel R. Schroeder Carl W. White Tara N. Jones Tara B. Hendry-Hofer Brian J. Day Sandra S. Eaton 《Applied magnetic resonance》2011,40(1):125-134
The superoxide dismutase (SOD)-mimetic effectiveness of [meso-tetrakis(R)porphyrinato]manganese with R = 1,3-di-N-ethylimidazolium-2-yl (Mn-TDEIP), 1,3-di-N-methylimidazolium-2-yl (Mn-TDMIP), 1,3-di-N-propylimidazolium-2-yl (Mn-TDPIP), N-ethyl-2-pyridyl (Mn-T2EPyP), 4-sulphonatophenyl (Mn-TSP), 1-methyl-4-pyridyl (Mn-T4PyP), 4-carboxyphenyl (Mn-TBAP), and β-octabromo-meso-tetrakis(4-carboxyphenyl
porphyrinato)manganese (MnBr8TBAP) was compared with Cu, Zn SOD. Superoxide generated by reaction of xanthine oxidase with hypoxanthine was trapped with
5-tert-butoxycarbonyl-5-methyl-1-pyrroline N-oxide (BMPO), forming BMPO–OOH, which was monitored by electron paramagnetic resonance. Manganoporphyrins with redox potentials
ranging from −0.190 to 0.346 V relative to the standard hydrogen electrode were selected for this study. With 0.1 μM manganoporphyrins
and 20 mM BMPO, the effectiveness of the manganoporphyrins in inhibiting formation of BMPO–OOH increases in the order Mn-TSP < Mn-TBAP < MnBr8TBAP < Mn-T4PyP < Mn-T2EPyP < Mn-TDEIP ~ Mn-TDMIP ~ Mn-TDPIP ~ Cu, Zn SOD. However, at higher concentrations of manganoporphyrin
and BMPO, a BMPO–OH signal was observed. The formation of BMPO–OH was not inhibited by catalase or dimethylsulfoxide, which
demonstrated that it was not produced from hydroxyl radical. The artifactual formation of BMPO–OH is attributed to oxidation
of the water adduct of BMPO by the manganoporphyrins or decomposition of BMPO–OOH. Although spin trapping is an effective
method for evaluating SOD-mimetic efficacy, caution must be exercised to ensure that artifact signals are not interpreted
improperly. 相似文献
155.
We examine nilpotency amongst blocks of positive defect of the quasisimple groups for the prime 2. We show that every nilpotent block of a quasisimple group has abelian defect groups, and prove a conjecture of Puig concerning the recognition of nilpotent blocks in the case of quasisimple groups. Explicit characterisations of nilpotent blocks are given for the classical, alternating and sporadic simple groups. 相似文献
156.
Tseitlin M Quine RW Eaton SS Eaton GR Halpern HJ Ardenkjaer-Larsen JH 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,209(2):306-309
The Frank polyphase sequence has been applied to pulsed EPR of triarylmethyl radicals at 25 6 MHz (9.1 mT magnetic field), using 256 phase pulses. In EPR, as in NMR, use of a Frank sequence of phase steps permits pulsed FID signal acquisition with very low power microwave/RF pulses (ca. 1.5 mW in the application reported here) relative to standard pulsed EPR. A 0.2 mM aqueous solution of a triarylmethyl radical was studied using a 16 mm diameter cross-loop resonator to isolate the EPR signal detection system from the incident pulses. 相似文献
157.
Tseitlin M Rinard GA Quine RW Eaton SS Eaton GR 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,211(2):156-161
In rapid frequency scan EPR with triangular scans, sufficient time must be allowed to insure that the magnetization in the x, y plane decays to baseline at the end of the scan, which typically is about 5T(2) after the spins are excited. To permit relaxation of signals excited toward the extremes of the scan the total scan time required may be much longer than 5T(2). However, with periodic, saw-tooth excitation, the slow-scan EPR spectrum can be recovered by Fourier deconvolution of data recorded with a total scan period of 5T(2), even if some spins are excited later in the scan. This scan time is similar to polyphase excitation methods. The peak power required for either polyphase excitation or rapid frequency scans is substantially smaller than for pulsed EPR. The use of an arbitrary waveform generator (AWG) and cross loop resonator facilitated implementation of the rapid frequency scan experiments reported here. The use of constant continuous low B(1), periodic excitation waveform, and constant external magnetic field is similar to polyphase excitation, but could be implemented without the AWG that is required for polyphase excitation. 相似文献
158.
Inês Gomes Maria J. Feio Nuno C. Santos Peter Eaton Ana Paula Serro Benilde Saramago Eulália Pereira Ricardo Franco 《Journal of nanoparticle research》2012,14(12):1-12
Herein, we present a novel method based on the use of the symmetrical T4 bacteriophage capsid as a scaffold for preparing the gold-coated iron ternary core/shell nanostructure. Results showed that the thick gold shell was obtained to effectively protect Fe core from oxidation. Magnetic measurements showed that the nanocomposites were superparamagnetic at room temperature with a blocking temperature of about 35?K. At 3?K, its coercivity of 1142.86 Oe was larger than the existing experimental values. The magnetic property of Au/T4 was also tested, demonstrating the source of the magnetic sample arising from the Fe core only. The absorption spectrum of the Fe@Au/T4 complex was measured and compared with gold/virus. Different thickness gold shells were controlled in the synthesis by tuning the Au salt addition. On the basis of results and discussion, we further speculated the general growing mechanism of the template-supported Fe@Au process. 相似文献
159.
160.
Modifications of the turbulent separated flow in an asymmetric three-dimensional diffuser due to inlet condition perturbations
were investigated using conventional static pressure measurements and velocity data acquired using magnetic resonance velocimetry
(MRV). Previous experiments and simulations revealed a strong sensitivity of the diffuser performance to weak secondary flows
in the inlet. The present, more detailed experiments were conducted to obtain a better understanding of this sensitivity.
Pressure data were acquired in an airflow apparatus at an inlet Reynolds number of 10,000. The diffuser pressure recovery
was strongly affected by a pair of longitudinal vortices injected along one wall of the inlet channel using either dielectric
barrier discharge plasma actuators or conventional half-delta wing vortex generators. MRV measurements were obtained in a
water flow apparatus at matched Reynolds number for two different cases with passive vortex generators. The first case had
a pair of counter-rotating longitudinal vortices embedded in the boundary layer near the center of the expanding wall of the
diffuser such that the flow on the outsides of the vortices was directed toward the wall. The MRV data showed that the three-dimensional
separation bubble initially grew much slower causing a rapid early reduction in the core flow velocity and a consequent reduction
of total pressure losses due to turbulent mixing. This produced a 13% increase in the overall pressure recovery. For the second
case, the vortices rotated in the opposite sense, and the image vortices pushed them into the corners. This led to a very
rapid initial growth of the separation bubble and formation of strong swirl at the diffuser exit. These changes resulted in
a 17% reduction in the overall pressure recovery for this case. The results emphasize the extreme sensitivity of 3D separated
flows to weak perturbations. 相似文献