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1.
The effect of divalent cations on the inactivation of Escherichia coli by high hydrostatic pressure was investigated. The presence of 0.5 mmol l-1 of CaCl2, MgCl2, MnCl2 and FeCl2 reduced pressure inactivation of E. coli MG1655, while 0.5 mmol l-1 of ZnCl2, NiCl2, CuCl2 and CoCl2 increased inactivation. Baroprotection by Ca2+ was found to be dose-dependent up to at least 80 mmol l-1 and was studied in more detail in terms of inactivation kinetics. Logarithmic survivor plots against time deviated from first order kinetics, suggesting that MG1655 cultures were heterogeneous with regard to pressure resistance. All cultures were shown to contain a small proportion of cells that were only slowly inactivated. Addition of Ca2+ increased the proportion of these tolerant cells in the cultures up to 1000-fold at 80 mmol l-1, but did not affect their inactivation rate. The addition of EDTA resulted in the opposite effect, lowering the proportion of pressure-tolerant cells in the cultures. Three pressure-resistant mutants of E. coli MG1655 were found to be more resistant to EDTA under pressure compared with MG1655, and were unaffected by Ca2+ under pressure. In addition, these mutants had a 30-40% lower Ca2+ content than MG1655. Based on these results, it is postulated that pressure killing of E. coli MG1655 is mediated primarily by the destabilization of Ca(2+)-binding components, and that the mutations underlying pressure resistance have resulted in pressure-stable targets with reduced Ca(2+)-binding affinity. 相似文献
2.
Jingxian Zhang Mikio Iwasa Dongliang Jiang 《Journal of the American Ceramic Society》2005,88(4):1013-1016
It has been well accepted that polyethylene imine (PEI) is an effective dispersant for silicon carbide (SiC) in aqueous media. However, after the addition of sintering additives (Al2 O3 and Y2 O3 ), this dispersing effect is reduced significantly. In this work, a second dispersant, citric acid, was used to resolve this problem. It was found that citric acid could decrease the slurry viscosity (without sintering additives) and enhance the PEI adsorption on SiC particle surface. The optimal amount of citric acid required to achieve a minimum viscosity for 55 vol% SiC suspensions was equal to ∼0.87 wt% (at pH ∼6.8). With the aid of citric acid, well-stabilized SiC suspensions (containing sintering additives) were realized, which exhibited slight shear thinning rheologies. After tape casting and SPS sintering, dense SiC samples were obtained with a homogeneous fine-crystalline microstructure. Results showed that citric acid was an effective dispersant for improving the dispersion of SiC particles containing sintering additives. 相似文献
3.
Y. Takano K. Hiraki T. Takahashi R. Kondo S. Kagoshima T. Hasegawa T. Mocihda Y. Iwasa 《Journal of Low Temperature Physics》2006,142(3-4):647-650
We carried out77Se NMR measurements on BETS2(Cl2TCNQ) under pressure in order to investigate the magnetic properties of the insulating state which appears above 0.6 GPa.
The relaxation rate 1/T1 at 0.7 GPa shows small peak-like anomaly at 20 K, indicating a spin density wave transition as observed in BETS2(Br2TCNQ). 相似文献
4.
Karayanni M. Papavassiliou G. Pissas M. Fardis M. Papagelis K. Prassides K. Takenobu T. Iwasa Y. 《Journal of Superconductivity and Novel Magnetism》2005,18(4):521-528
We report a11B NMR line shape and spin-lattice relaxation rate (1/(T
1
T)) study of pure and lightly carbon-doped MgB2−x
C
x
forx=0, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB2 exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of
boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase
ofH
c
2/c
with carbon doping with respect to pure MgB2. The spin-lattice relaxation rate 1/(T
1
T) demonstrates clearly the presence of a coherence peak right belowT
c in pure MgB2, followed by a typical BCS decrease on cooling. However, at temperatures lower than ≈10 K strong deviation from the BCS behavior
is observed, probably from residual contribution of the vortex dynamics. In the carbon-doped systems both the coherence peak
and the BCS temperature dependence of 1/(T
1
T) weaken, an effect attributed to the gradual shrinking of the σ hole cylinders of the Fermi surface with electron doping. 相似文献
5.
M. Karayanni G. Papavassiliou M. Pissas M. Fardis K. Papagelis K. Prassides T. Takenobu Y. Iwasa 《Journal of Superconductivity》2005,18(4):521-528
We report a 11B NMR line shape and spin-lattice relaxation rate (1/(T1T))(1/(T_1T)) study of pure and lightly carbon-doped MgB2-xCx_{2-x}{\rm C}_x for x = 0,0.02x = 0,0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB2_2 exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of
boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase
of Hcc2H^c_{c2} with carbon doping with respect to pure MgB2_2. The spin-lattice relaxation rate 1/(T1T)1/(T_1T) demonstrates clearly the presence of a coherence peak right below TcT_{\rm c} in pure MgB2_2, followed by a typical BCS decrease on cooling. However, at temperatures lower than ?\approx 10 K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the
carbon-doped systems both the coherence peak and the BCS temperature dependence of 1/(T1T)1/(T_1T) weaken, an effect attributed to the gradual shrinking of the σ hole cylinders of the Fermi surface with electron doping. 相似文献
6.
Single‐Crystal‐Like Organic Thin‐Film Transistors Fabricated from Dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (DNTT) Precursor–Polystyrene Blends 下载免费PDF全文
7.
8.
S Iwasa C Kitada I Yoshida K Kondo M Hori M Fujino 《Canadian Metallurgical Quarterly》1981,89(4):1091-1099
A highly specific enzyme immunoassay for determining hCG was established by using beta-D-galactosidase as label. In order to increase the specificity of the assay, an antiserum against whole hCG was purified on a column of hCG beta carboxyl-terminal peptide (residues 123-145) covalently linked to Sepharose 4B. The antibody (N101S) thus prepared showed a weak cross-reactivity with human LH in an assay using hCG-enzyme conjugate, but the slight cross-reactivity was virtually avoided when an hCG beta carboxyl-terminal peptide was used as a peptide in the enzyme conjugate. N101S antibody was compared with antiserum (B1B) directed against a carboxyl-terminal peptide (123-145). In hCG measurement N101S gave about 30 times higher sensitivity than B1B, although the former antibody was less sensitive to carboxyl-terminal peptides of hCG beta. The enzyme immunoassay using a combination of N101S antibody and a carboxyl-terminal peptide (130-145)-enzyme conjugate was able to detect as little as 0.25 mIU of hCG without the interference of LH. The performance and validity of this assay were comparable to those of conventional radioimmunoassay. 相似文献
9.
10.
Orihara S. Iwasa S. Majima T. Nogiwa K. Yamagishi K. 《IEEE transactions on magnetics》1975,11(6):1685-1688
A 10-kbit bubble memory chip has been designed and fabricated. Testing was accomplished using a new diagnostic test system, which can drive the bubble chip at two different speeds with bias fields switched synchronously with the bubble propagation. Bias margins of the fabricated chips were analyzed and it was confirmed that a sufficient bias-margin window could be assured in long-term operation. 相似文献