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1.
P Nürnberg I Barth E Fuhrmann C Lenzner T Losanova C Peters H P?che G Thiel 《Electrophoresis》1991,12(2-3):186-192
Germline and somatic instability of the human genome was studied, using synthetic oligonucleotides specific for simple repeat motifs. The following probes were used: (GTG)5, (GACA)4, (GATA)4, (CT)8, (TTAGGG)3, (GT)8, (GAA)6 and (GGAT)4. Each of them is unique with respect to the target regions recognized in the genome. Thus compilation of the various fingerprint data provides a complex map of the genome (and its deviations). While the fingerprints of differentiated somatic tissues never showed any alterations, in tumor tissues (namely gliomas) many changes could be detected. Most of the latter reflect secondary karyological aberrations. In nearly one third of the gliomas, drastically amplified and apparently monomorphic DNA fragments were identified. This marker should make it possible to deal with causal pathogenetic mechanisms as well as novel diagnostic strategies. 相似文献
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S. Barth H. R. Ott F. N. Gygax B. Hitti E. Lippelt A. Schenck Z. Fisk 《Hyperfine Interactions》1989,50(1-4):709-716
μ+ SR-measurements in transversally applied magnetic fields of 2000 G and 4000 G on heavy-electron single crystal U2Zn17 are presented. They reveal that at least two types of interstitial sites are occupied by the positive muons. One of these
sites (1/3, 2/3, 5/6) could be identified via induced local dipolar fields which aboveT
N=9.7 K can exactly be derived from the magnetic susceptibility. The corresponding component of the μ+-signal exhibits a steplike decrease by about 40% atT
N which is caused by the onset of a very broad distribution of static internal magnetic fields (ΔB≈1000 G) with zero average. Such a field distribution is in distinct contrast to dipolar-field calculations performed for
the simple antiferromagnetic structure deduced from neutron diffraction. The remaining 60% of the muons contributing to this
component belowT
N are subject to a narrow static field distribution (ΔB≈1 G). The induced dipolar fields at the site (1/3, 2/3, 5/6) are temperature-independent belowT
N. A weak dipolar coupling to the U-moments renders similar observations for muons occupying the second type of interstitial
impossible. 相似文献
5.
F. N. Gygax B. Hitti E. Lippelt A. Schenck S. Barth 《Zeitschrift für Physik B Condensed Matter》1988,71(4):473-490
Using a high purity Bi single crystal the temperature and orientation dependence of the zero and transverse field muon spin relaxation rate has been studied in detail. The results imply that the + occupies one of the two possible interstitial sites in the distorted rhombohedral crystal structure of Bi below 10 K and the other site above 80 K. At both sites the nearest neighbor Bi atoms are found to be shifted towards the + by 10% of their nominal distance, implying a large local lattice contraction. In concomitance extremely strong electric field gradients are manifest at the nn Bi nuclei. An almost temperature independent reduced relaxation rate in the temperature range from 20 K to 60 K is interpreted in terms of short range diffusion along a limited chain of alternating types of sites. Above 100 K both long range and short range diffusion are indicated. 相似文献
6.
Jana Mikulova Francois Gérard Danielle Mesnard Charles Kappenstein Daniel Duprez 《Journal of solid state chemistry》2006,179(8):2511-2520
CeO2 doped with praseodymium, neodymium and/or zirconium atoms were prepared by coprecipitation and by the sol-gel method. Structural properties were investigated by in situ XRD and Raman spectroscopy while oxygen storage capacity (OSC) was measured by transient CO oxidation. All the compounds, except pure Nd2O3, have a fluorite-type structure as well as a Raman band at 560 cm−1 characteristic of the oxygen vacancies involving non-stoichiometric oxides. The lattice parameter under hydrogen, being dependent on the temperature, revealed two reduction mechanisms: one at a low temperature at the surface and another at a high temperature in the bulk. Ce-Nd binary oxides show a strong tendency towards crystallite aggregation, which reduces accessibility to gases and OSC properties. Zirconium improves the thermal resistance to sintering of both Ce-Nd and Ce-Pr oxides. The Zr-Ce-Pr-O followed by Zr-Ce-Nd-O compounds displaying high oxygen mobility at a low temperature, appear to be very promising for practical applications such as OSC materials. 相似文献
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At pH 5 (AcOHAcONa) protonation of the enamine of 3,6,6-trimethylnorpinane 2-one (3-methylnopinone) yields the cis immonium ion 6 (X OAc), which isomerizes to the thermodynamically more stable trans immonium ion 6′ (X OAc). Under more strongly acid conditions (aqueous hydrochloric or perchloric acids), the enamonium salts 7 (X Cl or ClO4) are formed; these isomerize, with a rate increasing with decreasing acidity to the cis immonium salts 6, stable under these conditions. Epimerization of the cis salt 6 (X Cl), occurs in ethereal hydrogen chloride, the rate increasing also with decreasing acidity. At pH 5, hydrolysis of the enamine yields 3-methylnopinone, the proportion of the less thermodynamically stable trans isomer increasing with a rise in reaction temperature. 相似文献
9.
Maria de Fátima V. Marques Danielle Ramos Juliana D. Rego 《European Polymer Journal》2004,40(11):2583-2589
Ethylene and different amounts of 1,7-octadiene were copolymerized using the metallocene catalyst system ethylidene-bis(fluorenyl) zirconium dichloride and methylaluminoxane (MAO) at both 50 and 90 °C. The catalyst activity has slightly increased with the addition of low amounts of the diene in relation to the homopolymerization of ethylene. The obtained polymers were characterized according to their melting temperature (Tm) and crystallinity degree (xc) by differential scanning calorimetry (DSC). Weight-average molecular weight (Mw) and polydispersity were determined by gel permeation chromatography (GPC). Diene contents in the copolymer were obtained through the FTIR spectroscopy. The results indicated that at polymerization temperature of 90 °C, crosslinking bonds in the obtained copolymers were low, differently from what was observed at 50 °C. The diene content in the copolymer achieved more than 3 mol% and the comonomer conversion was around 15%. Moreover, the obtained copolymers have Mw around 100,000 and large polydispersity. 相似文献
10.
S. Steffen M. Otto L. Niewoehner M. Barth Z. Bro¿żek-Mucha J. Biegstraaten R. Horváth 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
A gunshot residue sample that was collected from an object or a suspected person is automatically searched for gunshot residue relevant particles. Particle data (such as size, morphology, position on the sample for manual relocation, etc.) as well as the corresponding X-ray spectra and images are stored. According to these data, particles are classified by the analysis-software into different groups: ‘gunshot residue characteristic’, ‘consistent with gunshot residue’ and environmental particles, respectively. Potential gunshot residue particles are manually checked and – if necessary – confirmed by the operating forensic scientist. 相似文献