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311.
Ikenaka Y Ishizaka M Eun H Miyabara Y 《Biochemical and biophysical research communications》2007,360(2):490-495
We found that aquatic crustaceans, decapoda; atyidae (Caridina multidentata, Neocaridina denticulate, and Paratya compressa), metabolize pyrene to a new conjugation product. The results of deconjugation treatments indicated that glucose and sulfate combined with 1-hydroxypyrene. Further analysis by LC/ESI-MS/MS showed that the molecular weight of the product was 460 (m/z 459; deprotonated ion), and that it has a glucose-sulfate moiety (m/z 241; fragment ion). These results indicated that the new metabolite was the glucose-sulfate conjugate of 1-hydroxypyrene. The glucose-sulfate conjugate is a phase II product that has not been reported previously from any organism. Several studies have demonstrated that sulfation is an important pathway for metabolism of xenobiotics in aquatic invertebrates. Thus, glucose-sulfate conjugates may add an important signal for excretion or sequestration of xenobiotics for aquatic invertebrates. 相似文献
312.
Wageh Sobhy Darwish Yoshinori Ikenaka Shouta Nakayama Mayumi Ishizuka 《Biological trace element research》2014,158(2):243-248
Copper (Cu2+) is an essential element that plays important roles in physiological functions of the body. However, high Cu2+ levels can have toxic implications. This study aims to investigate the constitutive response to Cu2+ exposure of xenobiotic-metabolizing enzymes in cultured rat liver (H4-II-E) cell lines. Rat cells were exposed to copper sulfate (0–500 μM) for 24 h. The effects of Cu2+ on the messenger RNA (mRNA) expressions of phase I and II enzymes and regulatory elements were examined using real-time PCR. Metallothionein mRNA expression was induced in a dose-dependent manner after treatment with Cu2+. mRNA expressions of phase I enzymes such as cytochrome P450 1A1 and 1A2 (CYP1A1 and CYP1A2) were slightly induced after exposure to low concentrations of Cu2+; however, CYP1A1 and CYP1A2 mRNA expressions were significantly downregulated at higher Cu2+ concentrations. These effects corresponded with expression of aryl hydrocarbon receptor mRNA. The mRNA expressions of phase II enzymes were reduced upon exposure to Cu2+. In conclusion, phase I and II enzyme expressions were significantly modulated upon Cu2+ exposure. These results indicated that Cu2+ exposure had toxicological implications for cultured H4-II-E cells. 相似文献
313.
Various animal models are available for studying human multiple sclerosis (MS). Most of them model the initial phase of MS,including the immune-triggered attack of the myelin membrane and/or oligodendrocytes and, occasionally, demonstrate there mission and relapsing phases. However, few mimic the late chronic demyelinating phase. Overexpression of the proteolipid protein gene (Plp) causes a unique demyelinating disorder in mice in which normal-appearing myelin forms early in life and chronic demyelination occurs later. We found that remyelination is severely affected in this late demyelinating phase, but is not caused by deprivation of oligodendrocyte progenitors expressing PDGF receptor alpha (PDGFRa) and Olig2, which are present at an even higher number in the demyelinated white matter of the mutants than in wild-type controls. Furthermore, mature oligodendrocytes containing PLP were observed, but failed to remyelinate. The ability of oligodendrocytes from older transgenic animals to produce a myelin membrane-like structure was not impaired when cultured in vitro, which indicates that the lack of remyelination is not simply caused by changes in the intrinsic properties of the oligodendrocytes. Glial activation also occurred much earlier than active demyelination in mutant mice. Thus, in addition to intrinsic mechanisms, extrinsic mechanisms might also have an important role in defects of remyelination. These features are also observed in patients at a late stage of MS, leading to chronic demyelinating lesions. Thus, this mouse model partly mimics the late stage of MS and can be used to study the cause of inhibition of remyelination. 相似文献
314.
315.
The contribution of the P1' residue at the first reactive site of peanut protease inhibitor B-III to the inhibition was analyzed by replacement of the P1' Arg(11) with other amino acids (Arg, Ser, Ala, Leu, Phe, Asp) after selective modification of the second reactive site. The Arg derivative had the same trypsin inhibitory activity as the native inhibitor (Ki = 2 X 10(-9) M). The Ser derivative inhibited more weakly (Ki = 2 X 10(-8) M). The Ala and Leu derivatives inhibited trypsin very weakly (Ki = 2 X 10(-7) M and 4 X 10(-7) M, respectively), and the Phe and Asp derivatives not at all. These results suggest that the P1' arginine residue is best for inhibitory activity at the first reactive site of B-III, although it has been suggested that a P1' serine residue at the reactive site is best for inhibitory activity of Bowman-Birk type inhibitors. 相似文献
316.
Yuji Koide Mamoru Honma Tokuji Shimomura 《Bioscience, biotechnology, and biochemistry》2013,77(7):1171-1177
Branched chain amino acid aminotransferase was partially purified from Pseudomonas sp. by ammonium sulfate fractionation, aminohexyl-agarose and Bio-Gel A-0.5 m column chromatography.This enzyme showed different substrate specificity from those of other origins, namely lower reactivity for l-isoleucine and higher reactivity for l-methionine.Km values at pH 8.0 were calculated to be 0.3 mm for l-leucine, 0.3 mm for α-ketoglutarate, 1.1 mm for α-ketoisocaproate and 3.2 mm for l-glutamate.This enzyme was activated with β-mercaptoethanol, and this activated enzyme had different kinetic properties from unactivated enzyme, namely, Km values at pH 8.0 were calculated to be 1.2 mm for l-leucine, 0.3 mm for α-ketoglutarate.Isocaproic acid which is the substrate analog of l-leucine was competitive inhibitor for pyridoxal form of unactivated and activated enzymes, and inhibitor constants were estimated to be 6 mm and 14 mm, respectively. 相似文献
317.
Abdullah Asmaa Hayashi Yoshitaka Morimura Naoko Kumar Akhilesh Ikenaka Kazuhiro Togayachi Akira Narimatsu Hisashi Hitoshi Seiji 《Neurochemical research》2022,47(9):2793-2804
Neurochemical Research - α1,3-Fucosyltransferase 9 (Fut9) is responsible for the synthesis of Lewis X [LeX, Galβ1-4(Fucα1-3)GlcNAc] carbohydrate epitope, a marker for pluripotent or... 相似文献
318.
319.
The structure of Bowman-Birk type protease inhibitor A-II from peanut (Arachis hypogaea) at 3.3 A resolution 总被引:2,自引:0,他引:2
A Suzuki Y Tsunogae I Tanaka T Yamane T Ashida S Norioka S Hara T Ikenaka 《Journal of biochemistry》1987,101(1):267-274
The structure of Bowman-Birk type protease inhibitor (A-II from peanut) is described at 3.3 A resolution. The molecules form a tetramer with 222 local symmetry in our crystals. Each monomer has an elongated shape with approximate dimensions of 45 X 15 X 15 A and consists of two distinct domains. The three-dimensional structures of the two domains are similar and are related by the intramolecular approximate twofold rotation axis. The two independent protease binding sites protrude from the molecular body on opposite sides. A scheme for the molecular evolution of the double-headed Bowman-Birk type protease inhibitors is proposed, based on the three-dimensional structure. 相似文献
320.
Tokuji Tsuchiya 《Analytical biochemistry》2009,388(1):158-407
Polymerase chain reaction (PCR)-based genome walking techniques are commonly used to clone unknown genomic regions flanking known sequences. However, these methods are typically problematic when applied to highly complex DNA templates isolated from plants with large genomes. Here we describe a reliable and efficient genome walking method that is particularly effective for plants with large genomes. Our ligation-mediated PCR method, Straight Walk, has improved sensitivity and specificity due to optimization of sequences of adaptors and adaptor primers. Successful genome walking in lily, which has one of the largest genomes in plants, indicates that Straight Walk is applicable for most plant species. 相似文献