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91.
Lactate dehydrogenase (LDH) activity and the character of its isoenzyme distribution in pancreas of the human embryos and feti of the 5th-13th-week development were studied. It is shown that LDH activity was rather high already in early periods of the embryonic development, peaks of the enzymic activity were observed after 7-8 and 12-13 weeks. The isoenzymic LDH spectrum was characterized by the presence of four isoenzymes: LDH1, LDH2, LDH3, LDH5. Isoenzyme LDH4 was absent in the human pancreas in all the studied periods of embryonic development. The data obtained evidence for intensity of the glycolysis processes at LDH reaction level in the prenatal ontogenesis period and they reflect most probably the processes of development and differentiation ox cellular populations in the given organ. 相似文献
92.
Using the reaction of activated N-hydrooxisuccinimide ester of mycophenolic acid, a series of immunoreactive conjugated antigens
with albumins, gelatin, and glucosoxidase is obtained. On the basis of polyclonal rabbit antibodies, a test-system for indirect
competitive immunoenzyme analysis is elaborated, which has the sensitivity 0.4 ng/ml. By immunoanalysis, the ability for active
biosynthesis of mycophenolic acid in strains of Byssochlamys nivea (44/44, 4100-68400 ng/ml) and Penicillium roqueforti (7/16, 204-25120 ng/ml) from the mycobiota of ensiled feeds is confirmed. The correspondence between weakly expressed producing
capacity of most species of fungi of the genera Penicillium and Aspergillus prevailing in grain feeds and the data on low occurrence of this metabolite in grain (8.0%) and combined feeds (11.9%) is
confirmed. A potential relationship between particular cases of a significant accumulation of mycophenolic acid (from 500
to 1500 μg/kg) in grains of wheat, corn, and combined feeds and a high biosynthetic activity in rare species P. puberulum, P. stoloniferum, and P. gladioli is discussed. 相似文献
93.
A theoretical model of conformation--regulated electron transfer from multihaem cytochrome c to bacteriochlorophyll of the reaction centre (RC) is considered. The theoretical data are compared with the experimental ones on the basis of temperature dependence of laser-induced electron transfer from high-potential cytochrome Ch bacheriochlorophyll of RC in Ectothiohodospira shaposhnikovii chromatophores. From this comparison there were calculated the thermodynamic characteristics of cytochrome Ch transfer from the configuration without electron transfer to RC bacteriochlorophyll into the coordinated configuration with an effective transfer. The values obtained are: H = 7,1 kJ/M; S = --(30,2--36,9) J/grad. M. Possible regulatory role of such conformation transitions is discussed. 相似文献
94.
Effects of acetylcholine, octopamine, and their antagonists, as well as of glutamic acid were studied on contractions of dorsal longitudinal muscle of the mollusc Lymnaea stagnalis L., evoked by electrical stimulation of n. cervicalis inferior. Acetylcholine and octopamine increased amplitude of contractions evoked by applications at concentrations about 10–8 M and decreased at concentrations higher than 10–7 M. Glutamic acid produced only inhibitory effect on the contraction amplitude, which appeared at concentrations beginning from 10–9 M and higher. The acetylcholine antagonists atropine and d-tubocurarine also decreased amplitude of evoked contractions. Their blocking effect rose with increase of their concentrations in the range from 10–9 M to 10–5 M. Specificity of the effect of the studied substances was established in experiments with a combined application of the transmitters and their antagonists. The obtained results indicate multiplicity of chemical mechanisms of regulation of contractions of the dorsal longitudinal muscle in L. stagnalis.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 1, 2005, pp. 44–50.Original Russian Text Copyright © 2005 by Kononenko, Zhukov. 相似文献
95.
The integral structural parameters and the shape of the molecule of human translation termination factor eRF1 were determined from the small-angle X-ray scattering in solution. The molecular shapes were found by bead modeling with nonlinear minimization of the root-mean-square deviation of the calculated from the experimental scattering curve. Comparisons of the small-angle scattering curves computed for atomic-resolution structures of eRF1 with the experimental data on scattering from solution testified that the crystal and the solution conformations are close. In the ribosome, the distance between the eRF1 motifs GGQ and NIKS must be shorter than in crystal or solution (75 versus 100–107 Å). Therefore, like its bacterial counterpart RF2, the eukaryotic eRF1 must change its conformation as it binds to the ribosome. The conformational mobility of eukaryotic and prokaryotic class-1 release factors is another feature making them functionally akin to tRNA. 相似文献
96.
Kononenko AV Mitkevich VA Dubovaya VI Kolosov PM Makarov AA Kisselev LL 《Proteins》2008,70(2):388-393
Eukaryotic translational termination is triggered by polypeptide release factors eRF1, eRF3, and one of the three stop codons at the ribosomal A-site. Isothermal titration calorimetry shows that (i) the separated MC, M, and C domains of human eRF1 bind to eRF3; (ii) GTP binding to eRF3 requires complex formation with either the MC or M + C domains; (iii) the M domain interacts with the N and C domains; (iv) the MC domain and Mg2+ induce GTPase activity of eRF3 in the ribosome. We suggest that GDP binding site of eRF3 acquires an ability to bind gamma-phosphate of GTP if altered by cooperative action of the M and C domains of eRF1. Thus, the stop-codon decoding is associated with the N domain of eRF1 while the GTPase activity of eRF3 is controlled by the MC domain of eRF1 demonstrating a substantial structural uncoupling of these two activities though functionally they are interrelated. 相似文献
97.
Formation kinetics, specificity, and analytical potential of polyclonal antibodies raised in rabbits against BSA conjugates of carboxymethyloxime-zearalanone (CMO-ZAN) and carboxymethyloxime-zearalenone (CMO-ZEN). Preparation of the conjugates involved conversion of CMO-ZAN and CMO-ZEN into activated esters and carbodiimide condensation. Two versions of a group-specific enzyme immunoassay (for zearalenone/alpha-zearalenone and zearalanol/alpha-zearalanol) based on heterologous combination of solid-phase antigens are described (sensitivity, 0.01 ng/ml). 相似文献
98.
Melina Overhoff Frederik Tellkamp Simon Hess Marianna Tolve Janine Tutas Marcel Faerfers Lotte Ickert Milad Mohammadi Elodie De Bruyckere Emmanouela Kallergi Andrea Delle Vedove Vassiliki Nikoletopoulou Brunhilde Wirth Joerg Isensee Tim Hucho Dmytro Puchkov Dirk Isbrandt Marcus Krueger Peter Kloppenburg Natalia L Kononenko 《The EMBO journal》2022,41(22)
Autophagy provides nutrients during starvation and eliminates detrimental cellular components. However, accumulating evidence indicates that autophagy is not merely a housekeeping process. Here, by combining mouse models of neuron‐specific ATG5 deficiency in either excitatory or inhibitory neurons with quantitative proteomics, high‐content microscopy, and live‐imaging approaches, we show that autophagy protein ATG5 functions in neurons to regulate cAMP‐dependent protein kinase A (PKA)‐mediated phosphorylation of a synapse‐confined proteome. This function of ATG5 is independent of bulk turnover of synaptic proteins and requires the targeting of PKA inhibitory R1 subunits to autophagosomes. Neuronal loss of ATG5 causes synaptic accumulation of PKA‐R1, which sequesters the PKA catalytic subunit and diminishes cAMP/PKA‐dependent phosphorylation of postsynaptic cytoskeletal proteins that mediate AMPAR trafficking. Furthermore, ATG5 deletion in glutamatergic neurons augments AMPAR‐dependent excitatory neurotransmission and causes the appearance of spontaneous recurrent seizures in mice. Our findings identify a novel role of autophagy in regulating PKA signaling at glutamatergic synapses and suggest the PKA as a target for restoration of synaptic function in neurodegenerative conditions with autophagy dysfunction. 相似文献
99.
Nonglutamate pore residues in ion selection and conduction in voltage-gated Ca(2+) channels 下载免费PDF全文
High-affinity, intrapore binding of Ca(2+) over competing ions is the essential feature in the ion selectivity mechanism of voltage-gated Ca(2+) channels. At the same time, several million Ca(2+) ions can travel each second through the pore of a single open Ca(2+) channel. How such high Ca(2+) flux is achieved in the face of tight Ca(2+) binding is a current area of inquiry, particularly from a structural point of view. The ion selectivity locus comprises four glutamate residues within the channel's pore. These glutamates make unequal contributions to Ca(2+) binding, underscoring a role for neighboring residues in pore function. By comparing two Ca(2+) channels (the L-type alpha(1C), and the non-L-type alpha(1A)) that differ in their pore properties but only differ at a single amino acid position near the selectivity locus, we have identified the amino-terminal neighbor of the glutamate residue in motif III as a determinant of pore function. This position is more important in the function of alpha(1C) channels than in alpha(1A) channels. For a systematic series of mutations at this pore position in alpha(1C), both unitary Ba(2+) conductance and Cd(2+) block of Ba(2+) current varied with residue volume. Pore mutations designed to make alpha(1C) more like alpha(1A) and vice versa revealed that relative selectivity for Ba(2+) over K(+) depended almost solely on pore sequence and not channel type. Analysis of thermodynamic mutant cycles indicates that the motif III neighbor normally interacts in a cooperative fashion with the locus, molding the functional behavior of the pore. 相似文献
100.
G. P. Kononenko A. A. Burkin E. V. Zotova N. A. Soboleva 《Applied Biochemistry and Microbiology》2000,36(2):177-180
Ochratoxin A was quantitatively monitored in grain extracts by indirect solid-phase enzyme immunoassay with the use of an
immobilized conjugate of the toxin with gelatin and polyclonal rabbit antibodies raised against the ochratoxin A-BSA conjugate.
This monitoring found that 1.7 to 18.5% of the samples were contaminated with the toxin at a concentration of 25.9–291.7 μg/kg.
An analysis of forage grain found ochratoxin A at concentrations of 440-3250 μg/kg. 相似文献