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41.
Some common properties of the protein that incorporates tyrosine as a single unit and the microtubule proteins 总被引:20,自引:0,他引:20
H S Barra C A Arce J A Rodríguez R Caputto 《Biochemical and biophysical research communications》1974,60(4):1384-1390
Properties so far studied of the protein that incorporates tyrosine show remarkable similarities with those of the microtubule proteins. The molecular weight of proteinyl-14C-tyrosine determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 54,000. The acceptor protein and proteinyl-14C-tyrosine were found in different states of aggregation; one of these states is apparently a dimer of molecular weight approximately 110,000. From a single preparation of proteinyl-14C-tyrosine variable proportions of dimer and higher molecular weight aggregates were obtained by incubating in different conditions. Proteinyl-14C-tyrosine was eluted from DEAE-Sephadex A-50 similarly to 3H-colchicine-tubulin complex. The pattern of elution from Sephadex G-200 of dimer proteinyl-14C-tyrosine was similar to that of 3H-colchicine-tubulin complex. Proteinyl-14C-tyrosine was precipitated with vinblastine sulfate. 相似文献
42.
Sandra J. Bucci Fabian G. Scholz Guillermo Goldstein Frederick C. Meinzer Maria E. Arce 《Oecologia》2009,160(4):631-641
Adaptations of species to capture limiting resources is central for understanding structure and function of ecosystems. We
studied the water economy of nine woody species differing in rooting depth in a Patagonian shrub steppe from southern Argentina
to understand how soil water availability and rooting depth determine their hydraulic architecture. Soil water content and
potentials, leaf water potentials (ΨLeaf), hydraulic conductivity, wood density (ρw), rooting depth, and specific leaf area (SLA) were measured during two summers. Water potentials in the upper soil layers
during a summer drought ranged from −2.3 to −3.6 MPa, increasing to −0.05 MPa below 150 cm. Predawn ΨLeaf was used as a surrogate of weighted mean soil water potential because no statistical differences in ΨLeaf were observed between exposed and covered leaves. Species-specific differences in predawn ΨLeaf were consistent with rooting depths. Predawn ΨLeaf ranged from −4.0 MPa for shallow rooted shrubs to −1.0 MPa for deep-rooted shrubs, suggesting that the roots of the latter
have access to abundant moisture, whereas shallow-rooted shrubs are adapted to use water deposited mainly by small rainfall
events. Wood density was a good predictor of hydraulic conductivity and SLA. Overall, we found that shallow rooted species
had efficient water transport in terms of high specific and leaf specific hydraulic conductivity, low ρw, high SLA and a low minimum ΨLeaf that exhibited strong seasonal changes, whereas deeply rooted shrubs maintained similar minimum ΨLeaf throughout the year, had stems with high ρw and low hydraulic conductivity and leaves with low SLA. These two hydraulic syndromes were the extremes of a continuum with
several species occupying different portions of a gradient in hydraulic characteristics. It appears that the marginal cost
of having an extensive root system (e.g., high ρw and root hydraulic resistance) contributes to low growth rates of the deeply rooted species. 相似文献
43.
L. P. G. D’Arce C. L. Bassi A. L. Fachin G. A. S. Passos E. T. Sakamoto-Hojo 《Genetica》2009,136(3):471-478
Illegitimate V(D)J-recombination in lymphoid malignancies involves rearrangements in immunoglobulin or T-cell receptor genes,
and these rearrangements may play a role in oncogenic events. High frequencies of TRGV-BJ hybrid gene (rearrangement between
the TRB and TRG loci at 7q35 and 7p14-15, respectively) have been detected in lymphocytes from patients with ataxia telangiectasia
(AT), and also in patients with lymphoid malignancies. Although the TRGV-BJ gene has been described only in T-lymphocytes,
we previously detected the presence of TRGV-BJ hybrid gene in the genomic DNA extracted from SV40-transformed AT5BIVA fibroblasts
from an AT patient. Aiming to determine whether the AT phenotype or the SV40 transformation could be responsible for the production
of the hybrid gene by illegitimate V(D)J-recombination, DNA samples were extracted from primary and SV40-transformed (normal
and AT) cell lines, following Nested-PCR with TRGV- and TRBJ-specific primers. The hybrid gene was only detected in SV40-transformed
fibroblasts (AT-5BIVA and MRC-5). Sequence alignment of the cloned PCR products using the BLAST program confirmed that the
fragments corresponded to the TRGV-BJ hybrid gene. The present results indicate that the rearrangement can be produced in
nonlymphoid cells, probably as a consequence of the genomic instability caused by the SV40-transformation, and independently
of ATM gene mutation. 相似文献
44.
Aminoalditol 1-amino-1-deoxy-D-sorbitol (1) was readily converted into 2,3,4,5-tetra-O-methyl derivative 5, a key precursor of a sugar-based [n]-polyurethane. For the polymerization, the free amino or primary hydroxyl groups of 5 were selectively activated and employed as starting monomers in two alternative procedures. Thus, the amino function of 5 was converted into the isocyanate derivative by treatment with di-tert-butyltricarbonate, and polymerized in situ in the presence of Zr(IV) acetylacetonate. The resulting poly(1-amino-1-deoxy-2,3,4,5-tetra-O-methyl-D-sorbitol)urethane (8) had a moderate molecular weight and showed the presence of urea units. The alternative synthesis of 8 involved the activation of the free hydroxyl group of 5 as the corresponding phenylcarbonate. The polymerization of this α-amino-ω-phenylcarbonate alditol monomer does not require a metal catalyst. The resulting material exhibited an improved molecular weight and higher purity than that obtained via the isocyanate. [n]-polyurethane 8 was highly soluble in water as well as in common organic solvents (chloroform, acetone, ethyl acetate, etc) and was obtained as an amorphous material which was characterized thermally and spectroscopically. 相似文献
45.
46.
C. A. Arce Marta E. Hallak J. A. Rodriguez H. S. Barra R. Caputio 《Journal of neurochemistry》1978,31(1):205-210
Abstract— Incorporation of [14 C]tyrosine into the C-terminal position of α-tubulin of rat brain cytosol was 10-fold higher for non-assembled than for assembled tubulin. The incorporation into tubulin from disassembled microtubules was higher than into non-assembled tubulin; therefore, the low incorporation into microtubules was not due to a lower acceptor capacity of their tubulin constituent.
[14 C]Tyrosine was released from assembled and non-assembled [14 C]tyrosinated tubulin by the action of an endogenous carboxypeptidase. Release from non-assembled tubulin was shown by incubating a tubulinyl-[14 C]tyrosine preparation in the presence of CaCl2 at a concentration that abolished microtubule formation. Release from microtubules was inferred from the observation that the percentages of [14 C]tyrosine released and the decrease of the specific radioactivity of the recovered microtubules were practically identical and did not change after a 10-fold dilution of the incubated microtubules.
[3 H]Phenylalanine was released from a preparation of tubulinyl-[3 H]phenylalanine also by an enzymatic activity.
The capacity of a tubulin preparation to incorporate tyrosine was increased 43% by pre-treatment with endogenous carboxypeptidase.
Tubulin tyrosinated in vitro was assembled to the same extent as native tubulin. After a mixture of tubulinyl-[14 C]tyrosine and tubulinyl-[3 H]phenylalanine was partially assembled, the ratio of 14 C/3 H found in the microtubules was the same as in the non-assembled tubulin fraction. 相似文献
[
[
The capacity of a tubulin preparation to incorporate tyrosine was increased 43% by pre-treatment with endogenous carboxypeptidase.
Tubulin tyrosinated in vitro was assembled to the same extent as native tubulin. After a mixture of tubulinyl-[
47.
48.
J A Aguilera V Garcia-Molina F Rodriguez-Vico V Arce A Linares E Garcia-Peregrin 《Archives internationales de physiologie et de biochimie》1988,96(2):121-126
The mevalonate incorporation in vivo into total nonsaponifiable lipids by chick kidneys drastically increased after hatching, reaching similar levels to those previously observed in liver. Cholesterol was the major sterol formed from mevalonate from 11 days onward, while a fraction of polar nonsaponifiable lipid(s) was observed as the major compound(s) synthesized at 5-8 days. Relative percentages of squalene, squalene oxide(s) and lanosterol synthesized from mevalonate also increased between 11-18 days after hatching. Results in this paper demonstrate for the first time the accumulation of a fraction of nonsaponifiable lipid(s) identified as lanosterol derivatives and cholesterol precursors formed by kidneys from [5-14C]mevalonate in experiments carried out in vivo, as well as their evolution during postnatal period. 相似文献
49.
Mapping of epitopes, glycosylation sites, and complement regulatory domains in human decay accelerating factor. 总被引:30,自引:0,他引:30
K E Coyne S E Hall S Thompson M A Arce T Kinoshita T Fujita D J Anstee W Rosse D M Lublin 《Journal of immunology (Baltimore, Md. : 1950)》1992,149(9):2906-2913
Decay accelerating factor (DAF, CD55) is a glycophospholipid-anchored membrane protein that protects cells from complement-mediated damage by inhibiting the formation and accelerating the decay of C3/C5 convertases. DAF deletion mutants lacking each of the four short consensus repeats (SCR) or the serine/threonine-rich region (S/T) were created by site-directed mutagenesis. These deletion mutants were expressed by stable transfection in Chinese hamster ovary cells for the purpose of mapping important structural and functional sites in DAF. The epitopes on DAF for 16 murine mAb were mapped by immunoprecipitation studies as follows: SCR1, 6; SCR2, 3; SCR3, 3; SCR4, 3; S/T, 1. Testing of 13 mAb showed complete blocking of DAF function only by 1C6 and 1H4, both directed at SCR3. The single N-linked glycosylation site was confirmed at a location between SCR1 and SCR2, and the multiple O-linked oligosaccharides were localized to the S/T region. Functional activity of DAF mutants was assessed by the ability of these transfected constructs to protect Chinese hamster ovary cells from cytotoxicity induced by rabbit antibody plus human complement. Removal of SCR1 had no effect on DAF function, but individual deletion of SCR2, SCR3, or SCR4 totally abolished DAF function. Surprisingly, deletion of the S/T region totally abrogated DAF function, but this could be restored by a fusion construct placing the four SCR domains of DAF onto the HLA-B44 molecule, implying that the O-glycosylated S/T region serves as an important but nonspecific spacer projecting the DAF functional domains above the plasma membrane. Overall, the creation of DAF deletion mutants has elucidated important structure-function relations in the DAF molecule. 相似文献
50.
Leticia Aguilar Doroteo Paola Berenice Zárate Segura Ramón Villanueva Arce Jorge Yáñez Fernández María Eugenia Garín Aguilar Paula Cecilia Guadarrama Mendoza Gustavo Valencia del Toro 《Revista iberoamericana de micología》2018,35(1):49-55