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排序方式: 共有325条查询结果,搜索用时 15 毫秒
101.
Yoshiya Akagi Hiroyuki Sasakura Satoru Noguchi Shigeki Tsukui Takashi Oka Motoaki Adachi 《Journal of Superconductivity and Novel Magnetism》2004,17(3):449-453
The Ru-1232 compounds have been synthesized in the (Ru1?xNb x )Sr2(GdCe1.8Sr0.2)Cu2O z system, and effects of Nb substitution for Ru on superconductivity and ferromagnetism of the Ru-1232 compounds have been investigated. First, X-ray powder diffraction study shows that nearly the single 1232 phase samples can be obtained in the x composition range from 0.0 to 0.3. Then, from the electrical resistivity study, it is found that each of the samples shows resistivity dropping phenomenon at two temperatures of T c l and T c h, which originates from superconductivity of the Ru-1232 phase and the Ru-1222 one, respectively. Both of the starting temperatures are lowering with increasing Nb content x. Lastly, from the magnetic susceptibility study, it is found that superconducting transition temperature T c is 20 K for the Ru-1232 sample with x = 0.0 and the ferromagnetic transition temperature T m is about 90 K. This study also shows that both of the values of T c and T m become low with increasing x from 0.0 to 0.3. 相似文献
102.
Hayashi E Kuramitsu Y Fujimoto M Zhang X Tanaka T Uchida K Fukuda T Furumoto H Ueyama Y Nakamura K 《Proteomics. Clinical applications》2009,3(11):1338-1347
Oral squamous cell carcinoma (OSCC) has an absolute majority of all oral cancer. We used proteomic technology to analyze the protein expression profile in OSCC tissues and accompanying surrounding normal tissues in four oral locations (buccal mucosa, gingival mucosa, oral floor, and tongue). Ten protein spots were overexpressed more strongly in cancer tissues than normal ones, and were identified as proliferating cell nuclear antigen, 14-3-3 ε, 14-3-3 σ, proteasome subunit α type 5, translationally controlled tumor protein, eukaryotic translation initiation factor 3 subunit, macrophage capping protein, and mitochondrial isocitrate dehydrogenase subunit α. Macrophage capping protein and mitochondrial isocitrate dehydrogenase subunit α had two spots. Especially, we focused on 14-3-3 σ protein, one of the eight identified proteins, and assessed its expression level in four oral locations of OSCC by using differential display methods. The expression level of 14-3-3 σ protein was upregulated in four locations of oral cavity. Eight proteins which we identified in this study may play an important role in OSCC carcinogenesis and progression and could be used as diagnostic biomarkers of OSCC. 相似文献
103.
Dynamics of iron-ascorbate-induced lipid peroxidation in charged and uncharged phospholipid vesicles
Peroxidation of egg yolk phosphatidylcholine (egg PC) liposomes was induced by addition of ascorbic acid (AsA) and Fe(II)
in the presence of a trace of autoxidized egg PC (PC−OOH), but not in the absence of PC−OOH. PC−OOH was degraded upon addition
of AsA and Fe(II) but not of either one alone. The results suggest that PC−OOH is necessary to initiate lipid peroxidation
by AsA/Fe(II). AsA oxidation in the bulk water phase was also associated with an increase in lipid peroxidation by AsA/Fe(II)
in the presence of PC−OOH, but not in the absence of PC−OOH. Furthermore, the spin probe 12-NS [12-(N-oxyl-4,4′-dimethyloxazolidin-2-yl)stearic acid], which labels the hydrophobic region of dimyristoyl phosphatidylcholine (DMPC)
liposomal membranes, was degraded upon addition of AsA and Fe(II) in the presence of PC−OOH, but not in the absence of PC−OOH.
These results indicate that the “induction message” that is associated with decreases of PC−OOH and AsA in the initiation
step of lipid peroxidation must be transferred from the membrane surface to the inner hydrophobic membrane region. AsA in
the bulk phase was oxidized faster and more extensively upon its addition together with Fe(II) to egg PC liposomes than to
DMPC liposomes, though the initial content of PC−OOH in the former was 5–10 times lower than in the latter. This suggests
that, in egg PC liposomes, the OOH-groups of new PC−OOH generated in the inner membrane regions must become accessible from
the surface, enabling reaction with AsA/Fe(II) which in turn would result in an extensive decrease in AsA. By contrast, in
DMPC liposomes, that do not generate PC−OOH, AsA is only oxidized slightly in connection with the degradation of the PC−OOH
initially present. The effect of surface charges on the membrane surface was also studied to obtain further information on
the initiation step of lipid peroxidation. The rate of lipid peroxidation by AsA/Fe(II) or Fe(III) decreased in the order,
egg PC liposomes ≫negatively charged egg PC liposomes containing dicetylphosphate>positively charge egg PC liposomes containing
stearylamine. The rate of associated AsA oxidation was in the order, egg PC liposomes≫egg PC/stearylamine liposomes>egg PC/dicetylphosphate
liposomes. However, in DMPC liposomes that do not generate PC−OOH, the rates of AsA oxidation associated with the reductive
cleavage of PC−OOH by AsA/Fe(II) and coupled with the reduction of Fe(III) to Fe(II) were in the order, DMPC liposomes =DMPC/stearylamine
liposomes≫DMPC/dicetylphosphate liposomes. These differences in the rates of lipid peroxidation, depending on differences
in membrane charge, are discussed in relation to two properties of AsA: (i) its antioxidant property through trapping of lipid
radicals and (ii) its prooxidant properties (a) by being an effective iron chelator thus altering the reactivity of iron with
oxygen and peroxides and (b) by being an iron reductant and providing a source of Fe(II). 相似文献
104.
Hiroyuki Sasakura Yoshiya Akagi Shigeki Tsukui Takashi Oka Motoaki Adachi 《Journal of Superconductivity》2004,17(4):509-512
There have been no report about synthesis of the Bi-2212 compound in the Bi–r–La–Cu–O system. We have succeeded in synthesizing the Bi-2212 compound by partial substitution of Pb for Sr and/or Bi in the Bi–Sr–La–Cu–O system. Two samples of nearly the single 2212 phase have been obtained at a nominal composition of Bi1.5Pb0.5Sr2.5La0.5Cu2O
z
. Both of the samples crystallize in a psedotetragonal lattice, and their lattice parameters are a = 0.5476 nm and c = 3.085 nm or a = 0.5479 nm and c = 3.055 nm. They are both superconductors. The sample with longer lattice parameter c shows an onset of the resistivity drop and zero resistivity at higher temperatures of about 40 K and about 13 K, respectively. This sample also shows a diamagnetic signal starting at about 35 K with lowering temperature. 相似文献
105.
Rotondaro A.L.P. Magnusson U.K. Claeys C. Flandre D. Terao A. Colinge J.-P. 《Electron Devices, IEEE Transactions on》1993,40(4):727-732
The threshold voltage for the three different conduction components of an accumulation-mode PMOS SOI were experimentally extracted at room and liquid-helium temperatures. A deep-depletion transient effect was observed to play an important role when one of the interfaces was in inversion, even at room temperature. An intuitive physical interpretation is given for the suppression of some current components at liquid-helium temperatures. In addition, a simple model for calculating the silicon-film thickness and the doping level is presented 相似文献
106.
Flandre D. Terao A. Francis P. Gentinne B. Colinge J.-P. 《Electron Device Letters, IEEE》1993,14(1):10-12
Measurements of accumulation-mode (AM) MOS SOI transistors in the 150-300°C temperature range are reported and discussed. The increases of the threshold voltage shift and off leakage current with temperature of these SOI p-MOSFETs are observed to be much smaller than their bulk equivalents. Simple models are presented to support the experimental data 相似文献
107.
Y Shimozuru S Yamane K Fujimoto K Terao S Honjo Y Nagai AD Sawitzke K Terato 《Canadian Metallurgical Quarterly》1998,41(3):507-514
A key event in signal transduction during chemotaxis of Salmonella typhimurium and related bacterial species is the interaction between the phosphorylated form of the response regulator CheY (CheY approximately P) and the switch of the flagellar motor, located at its base. The consequence of this interaction is a shift in the direction of flagellar rotation from the default, counterclockwise, to clockwise. The docking site of CheY approximately P at the switch is the protein FliM. The purpose of this study was to identify the CheY-binding domain of FliM. We cloned 17 fliM mutants, each defective in switching and having a point mutation at a different location, and then overexpressed and purified their products. The CheY-binding ability of each of the FliM mutant proteins was determined by chemical crosslinking. All the mutant proteins with an amino acid substitution at the N terminus, FliM6LI, FliM7SY and FliM10EG, bound CheY approximately P to a much lesser extent than did wild-type FliM. CheY approximately P-binding of the other mutant proteins was similar to wild-type FliM. To investigate whether the FliM domain that includes these three mutations is indeed the CheY-binding domain, we synthesized a peptide composed of the first 16 amino acid residues of FliM, including a highly conserved region of FliM (residues 6 to 15). The peptide bound CheY and, to a larger extent, CheY approximately P. It also competed with full-length FliM on CheY approximately P. These results indicate that the CheY-binding domain of FliM is located at the N terminus, within residues 1 to 16, and suggest that FliM monomers can form a complete site for CheY binding. 相似文献
108.
Effects of antiallergic drugs on bradykinin-induced histamine release and intracellular Ca2+ release from peritoneal mast cells were studied in rats. Bradykinin caused a concentration-dependent histamine release as well as Ca2+ release from the intracellular Ca store of peritoneal mast cells. Antiallergic drugs used in this study showed an inhibition of not only histamine release but also Ca2+ release. The Ca2+ release from the intracellular Ca store induced by bradykinin was more sensitive to antiallergic drugs than histamine release from mast cells. Mequitazine and terfenadine caused potent inhibitory effects on both responses, whereas effects of ketotifen and cromolyn sodium were relatively weak. In conclusion, histamine release from mast cells and intracellular C2+ release induced by bradykinin were inhibited by antiallergic drugs similar to those induced by substance P and compound 48/80. 相似文献
109.
Phospholipid hydroperoxides are detoxified by phospholipase A<Subscript>2</Subscript> and GSH peroxidase in rat gastric mucosa 总被引:1,自引:1,他引:0
The aim of this study was to determine the metabolic fate of phospholipid hydroperoxides (PLOOH) in rat gastric mucosa. Here
we report evidence concering the mechanism for PLOOH detoxification in gastric mucosa homogenate. Analysis by the TLC blot
technique showed that the gastric mucosa has the highest potential to eliminate 1-palmitoyl-2-linoleoyl-phosphatidylcholine
hydroperoxides (PL-PtdChoOOH) compared with the intestinal mucosa and liver. Major products detected after incubation with
gastric mucosa were the partially reduced linoleic acid hydroperoxides (LAOOH) and lysophosphatidylcholine, indicating the
involvement of phospholipase A2 (PLA2) in the elimination pathway. Using unilamellar vesicles, we demonstrated that gastric mucosal PLA2 does not distinguish between PLOOH and intact phospholipids. Although gastric mucosal PLA2 activity efficiently eliminated excess amounts of PLOOH, the complete reduction of LAOOH was dependent on the supply of exogenous
GSH. In a separate experiment, administration of egg yolk PtdChoOOH to rats for 6 d significantly elevated GSH peroxidase
(GPx) activity in the gastric mucosa. We concluded that excess amounts of PLOOH are efficiently eliminated through the hydrolysis
by PLA2, and the subsequent reduction of FA hydroperoxide by GPx is the critical step for complete detoxification of oxidized phospholipids
in the stomach. 相似文献
110.
Hydrocracking of Athabasca asphaltene over molten salts has been studied at 400 °C for 1 h at an initial hydrogen pressure of 9.8 M Pa. The hydrocracking over ZnCl2-KCl-NaCl produced 57.0 wt% of pentanesolubles (PS), 4.7 wt% of benzene-solubles (BS) and 22.7 wt% of gases together with 15.6 wt% of coke. These melts containing NiCl2 and CuCl, respectively, were examined, the former exerting a little better influence on reducing the coke yield. A small amount of coke (3.7%) and a higher conversion attained with ZnCl2-KCl-NaCl-MoCl5 suggested excellent properties of MoCl5 for the hydrocracking of asphaltene. The sulphur contents of the PS and BS were lowest with melt catalysts containing MoCl5. A compound-type separation of each pentane-soluble showed that in the presence of melt catalyst, monoaromatic and diaromatic contents increased greatly at the expense of polyaromatics and polar materials. The trend of catalytic activity of each melt for hydrocracking of asphaltene was found to be quite different from that for the decomposition reaction of tetrahydrothiophene in a continuous flow system. 相似文献