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21.
22.
Sulphur and phosphorus in steel were determined by neutron activation analysis, being counted as 35S and 32P respectively. For steels with sulphur to phosphorus ratios larger than 10, it seems possible to determine both elements by counting 32P, making use of a double irradiation technique at different fast to slow neutron fluxes. 相似文献
23.
A non-destructive neutron activation method was developed for the determination of silver and antimony in high-purity bismuth ; γ,γ-coincidence counting of 110mAg or 124Sb was applied. The activity of the matrix or other impurities did not interfere. When 1-g samples were irradiated at a neutron flux of 4·1011 n cm-2 sec-1 for 25 days, the sensitivity of the method was in the p.p.b. region. 相似文献
24.
Hauke Harms Julien Rime Olivier Leupin Stephan J. Hug Jan Roelof van der Meer 《Mikrochimica acta》2005,151(3-4):217-222
A luminescent bacterial biosensor was used to quantify bioavailable arsenic in artificial groundwater. Its light production
above the background emission was proportional to the arsenite concentration in the toxicologically relevant range of 0 to
0.5 μM. Effects of the inorganic solutes phosphate, Fe(II) and silicate on the biosensor signal were studied. Phosphate at
a concentration of 0.25 g L−1 phosphate slightly stimulated the light emission, but much less than toxicologically relevant concentrations of the much
stronger inducer arsenite. No effect of phosphate was oberved in the presence of arsenite. Freshly prepared sodium silicate
solution at a concentration of 10 mg L−1 Si reduced the arsenite-induced light production by roughly 37%, which can be explained by transient polymerization leading
to sequestration of some arsenic. After three days of incubation, silicate did not have this effect anymore, probably because
depolymerization occurred. In the presence of 0.4 mg L−1 Fe(II), the arsenite-induced light emission was reduced by up to 90%, probably due to iron oxidation followed by arsenite
adsorption on the less soluble Fe(III) possibly along with some oxidation to the stronger adsorbing As(V). Addition of 100 μM
EDTA was capable of releasing all arsenic from the precipitate and to transform it into the biologically measurable, dissolved
state. The biosensor also proved valuable for monitoring the effectiveness of an arsenic removal procedure based on water
filtration through a mixture of sand and iron granules. 相似文献
25.
A radiochemical method was developed to separate the group of the noble metals simultaneously from a lead matrix after irradiation with thermal neutrons. The resulting complex γ-spectrum was resolved by matrix calculus. Smoothing of the obtained data to determine the presence of small photopeaks among the background fluctuations, was done by convolution, based on a least squares approximation. The interference of antimony and bromine was studied. Amounts as low as 20–30 p.p.b. of Hg and less than 1 p.p.b. of Au were determined in the presence of up to 9 p.p.m. of Ag. 相似文献
26.
A non-destructive analytical method for oxygen in silicon by both helium-3 and α-particle activation analysis was applied to different samples, containing 0.05–10 p.p.m. of oxygen. The accuracy and precision of the method were studied. For concentrations above 1 p.p.m., the average coefficient of variation is about 6% for α-activation and 13% for helium-3 activation. For concentrations of about 60 p.p.b., the corresponding figure is about 20%. The results of both methods, which agree within 8%, are compared to infrared analysis. The determination limit of the method is 4 p.p.b. for helium-3 activation and 22 p.p.b. for α-activation. 相似文献
27.
Reactor neutron activation analysis of antimony, indium and cadmium in high-purity tin is interfered with by nuclear reactions
on the tin matrix. For a number of interfering reactions the cross-sections were determined. The following results were obtained:122Sn(n,γ)123mSn:σth=0.145 barn, I=0.79 barn;122Sn(n,γ)113Sn:σth=0.52, I=25.4 barn;112Sn(n, 2n)111Sn:
microbarn;118Sn(n, α)115Cd:
microbarn; and114Sn(n, p)114m1In:
microbarn. 相似文献
28.
A method was developed for the determination of 15 trace elements in tin. High-purity tin samples (99.9999% and 99.999%) as
well as tin of technical quality were analysed. Reactor neutron activation of the tin samples was followed by distillation
of the matrix activities from a HBr−H2SO4 medium and Ge(Li) gamma-ray spectrometry of the distillation residue. The sensitivity of the method is generally high. For
the high-purity samples the detection limits vary from 0.02 ppb (scandium) to 200 ppb (iron) for irradiation of 1 g of tin
for 1 week at a thermal flux of 5·1012n·cm−2. ·sec−1. To decontaminate the surface of the tin samples, pre- and post-irradiation etching procedures were applied. The efficiency
of these etching techniques was studied. 相似文献
29.
L. Moens A. Simonits F. De Corte J. Hoste 《Journal of Radioanalytical and Nuclear Chemistry》1979,54(1-2):377-390
For 13 isotopes, the resonance integral to thermal crosssection ratio was studied. The results of two different methods, applied
in two different laboratories, are compared. One method consists in a direct determination of I0/π0-values from Cd-ratio measurements, the other is based on the evaluation of literature data, using accurately determined k0-factors from two irradiation channels with largely different thermal-to-epithermal flux ratios. 相似文献
30.
Kadish KM Phan TD Wang LL Giribabu L Thuriere A Wellhoff J Huang S Caemelbecke EV Bear JL 《Inorganic chemistry》2004,43(16):4825-4832
Six Ru2(6+) derivatives of the form Ru2(L)4(C[triple bond]CC6H5)(2), where L = 2-Fap, 2,3-F(2)ap, 2,4-F(2)ap, 2,5-F(2)ap, 3,4-F(2)ap, or 2,4,6-F(3)ap, are synthesized and characterized as to their electrochemical, spectroscopic, and/or structural properties. These compounds are synthesized from a reaction between LiC[triple bond]CC6H5 and Ru2(L)4Cl. Two of the investigated complexes exist in a (4,0) isomeric form while four adopt a (3,1) geometric conformation. These two series of geometric isomers are compared with previously characterized (4,0) Ru2(ap)4(C[triple bond]CC6H5)(2), (4,0) Ru2(F5ap)4(C[triple bond]CC6H5)(2), and (3,1) Ru2(F5ap)4(C[triple bond]CC6H5)(2). The overall data on the nine compounds thus provide an opportunity to systematically examine how the electrochemical and structural properties of these Ru2(6+) complexes vary with respect to isomer type and electronic properties of the bridging ligands. 相似文献