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排序方式: 共有129条查询结果,搜索用时 22 毫秒
41.
Kana Sugimoto Hidekazu Tanaka Hiroshi Ochi Ryoji Matoba 《Biochemical and biophysical research communications》2009,390(4):1214-1807
Methamphetamine induces several cardiac dysfunctions, which leads to arrhythmia, cardiac failure and sudden cardiac death. Although these cardiac alterations elicited by methamphetamine were thought to be due to an indirect action of methamphetamine, namely, an excessive catecholamine release from synaptic terminals, while it seems likely that methamphetamine directly modulates the functioning of cardiomyocytes independent of neurotransmitters. However, the direct effects of methamphetamine on cardiomyocytes are still not clear. We show that methamphetamine directly accelerates the beating rate and alters Ca2+ oscillation pattern in cultured neonatal rat cardiomyocytes. Adrenergic receptor antagonists did not block the methamphetamine-induced alterations in cardiomyocytes. Treatment with a ryanodine receptor type 2 inhibitor and a sarcoplasmic reticulum Ca2+-ATPase inhibitor did not affect these responses, either. In contrast, the L-type Ca2+ channel inhibitor nifedipine eradicated these responses. Furthermore, methamphetamine elevated the internal free Ca2+ concentration in HEK-293T cells stably transfected with the L-type Ca2+ channel α1C subunit. In neonatal rat cardiomyocytes, methamphetamine accelerates beating rate and alters Ca2+ oscillation pattern by increasing Ca2+ entry via the L-type Ca2+ channels independent of any neurotransmitters. 相似文献
42.
Yu-Hong Liu Lars Konermann Dasantila Golemi-Kotra 《Journal of molecular biology》2009,391(1):149-20244
A two-component system consisting of the histidine kinase vancomycin-resistance-associated sensor and the response regulator vancomycin-resistance-associated regulator (VraR) allows Staphylococcus aureus to sense antibiotic-related cell wall stress and to mount a suitable response. An experimental structure of full-length VraR is not available yet, but previous work points to similarities between VraR and the well-characterized NarL. This work employs hydrogen exchange mass spectrometry to gain insights into the phosphorylation-induced activation of VraR, a process that primes the protein for dimerization and DNA binding. Whereas VraR is highly dynamic, phosphorylated VraR shows less extensive deuteration. This rigidification is most dramatic within the receiver domain, which carries the phosphorylation site D55. Alterations in the DNA-binding domain are much less pronounced. Changes in deuteration within the receiver domain are consistent with a Y-T coupling mechanism. In analogy to NarL, the activation of VraR is thought to involve separation and subsequent reorientation of the two domains, thereby allowing the α8-turn-α9 element to engage in DNA binding. The current work suggests that this structural transition is triggered by a reduction in the effective length of the linker through enhanced hydrogen bonding. In addition, separation of the two domains may be favored by the establishment of noncovalent protein-protein interactions and intradomain contacts at the expense of previously existing interdomain bonds. α9 appears to be packed against the receiver domain in nonactivated VraR. Support is presented for α1 as a dimerization interface in phosphorylated VraR, whereas protein-protein interactions for nonphosphorylated VraR are impeded by extensive disorder in this region. 相似文献
43.
R Miura Y Nishina M Ohta H Tojo K Shiga H Watari T Yamano Y Miyake 《Biochemical and biophysical research communications》1983,111(2):588-594
Resonance Raman (RR) spectra were measured for the purple intermediates of D-amino acid oxidase reconstituted with isotopically labelled FAD's, i.e., [4a-13C]-, [4,10a-13C2]-, [2-13C]-, [5-15N]-, and [1,3-15N2]flavin adenine dinucleotides, and compared with those with the native enzyme. The RR lines around 1605 cm-1 with D-alanine or D-proline as a substrate and at 1548 cm-1 with D-alanine undergo isotopic shifts upon [4a-13C]- and [4,10a-13C2]-labelling. These lines are assigned to the vibrational modes associated with C(10a) = C(4a) - C(4) = O moiety of reduced flavin, providing the first assignment of RR lines of reduced flavin and conclusive evidence that reduced flavin is involved in this intermediate. 相似文献
44.
We report and discuss Raman spectra of bacteriochlorophyll and of bacteriopheophytin obtained by resonance effect in their QX and Soret electronic bands. Selective excitation of spectra of either of these molecules in reaction centers of , strains Y and R 26, was achieved by illumination in their respective QX bands. Preliminary interpretation of the spectra yields information about the interactions assumed by these molecules in the reaction centers. Spheroidene bound to reaction centers of strain Y probably affects a conformation different from that assumed by the bulk spheroidene of the chromatophore. 相似文献
45.
Pyrococcus furiosus superoxide reductase (SOR) is a thermostable archaeal enzyme that reduces superoxide without producing oxygen. When produced as a fusion protein with the green fluorescent protein in plant cells, P. furiosus SOR is located in the cytosol and nucleus. The recombinant SOR enzyme retains its function and heat stability when assayed in vitro. Importantly, expressing SOR in plant cells enhances their survival at high temperature indicating that it functions in vivo. The archaeal SOR provides a novel mechanism to reduce superoxide and demonstrates the potential for using archaeal genes to alter eukaryotic metabolism. 相似文献
46.
Oinuma K Kumita H Ohta T Konishi K Hashimoto Y Higashibata H Kitagawa T Shiro Y Kobayashi M 《FEBS letters》2005,579(6):1394-1398
On stopped-flow analysis of aliphatic aldoxime dehydratase (OxdA), a novel hemoprotein, a spectrum derived from a reaction intermediate was detected on mixing ferrous OxdA with butyraldoxime; it gradually changed into that of ferrous OxdA with an isosbestic point at 421 nm. The spectral change on the addition of butyraldoxime to the ferrous H320A mutant showed the formation of a substrate-coordinated mutant, the absorption spectrum of which closely resembled that of the above intermediate. These observations and the resonance Raman investigation revealed that the substrate actually binds to the heme in OxdA, forming a hexa-coordinate low-spin heme. 相似文献
47.
Ioanitescu AI Dewilde S Kiger L Marden MC Moens L Van Doorslaer S 《Biophysical journal》2005,89(4):2628-2639
The nonsymbiotic tomato hemoglobin SOLly GLB1 (Solanum lycopersicon) is shown to form a homodimer of approximately 36 kDa with a high affinity for oxygen. Furthermore, our combined ultraviolet/visible, resonance Raman, and continuous wave electron paramagnetic resonance (EPR) measurements reveal that a mixture of penta- and hexacoordination of the heme iron is found in the deoxy ferrous form, whereas the ferric form shows predominantly a bis-histidine ligation (F8His-Fe(2+/3+)-E7His). This differs from the known forms of vertebrate hemoglobins and myoglobins. We have successfully applied our recently designed pulsed-EPR strategy to study the low-spin ferric form of tomato hemoglobin. These experiments reveal that, in ferric SOLly GLB1, one of the histidine planes is rotated 20 degrees (+/-10 degrees ) away from a N(heme)-Fe-N(heme) axis. Additionally, the observed g-values indicate a quasicoplanarity of the histidine ligands. From the HYSCORE (hyperfine sublevel correlation) measurements, the hyperfine and nuclear quadrupole couplings of the heme and histidine nitrogens are identified and compared with known EPR/ENDOR data of vertebrate Hbs and cytochromes. Finally, the ligand binding kinetics, which also indicate that the ferrous tomato Hb is only partially hexacoordinated, will be discussed in relation with the heme-pocket structure. The similarities and differences with other known nonsymbiotic plant hemoglobins will be highlighted. 相似文献
48.
Chang YS Peng SE Wang HC Hsu HC Ho CH Wang CH Wang SY Lo CF Kou GH 《Marine biotechnology (New York, N.Y.)》2001,3(2):163-171
In the present study, the existence of white spot syndrome virus (WSSV) in blue crab (Callinectes sapidus) collected from 3 different American coastal waters (New York, New Jersey, and Texas) was confirmed by 2-step diagnostic
polymerase chain reaction and in situ hybridization analysis. When geographic isolates were also compared using a gene that
encodes the WSSV ribonucleotide reductase large subunit RR1 (WSSV rr1), a C1661-to-T point mutation was found in the New Jersey WSSV isolated. This point mutation, which resulted in the creation of an
additional RsaI endonuclease recognition site, was not found in the WSSV from the New York and Texas blue crab samples, or in the WSSV Taiwan
isolate, or in any of the other WSSV geographical isolates for which data are available. WSSV rr1-specific RsaI amplified restriction fragment length polymorphism of an amplified 1156-bp fragment thus distinguished the New Jersey blue
crab samples from the other WSSV isolates.
Received June 29, 2000; accepted October 11, 2000 相似文献
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