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371.
372.
Summary The production of -carotene by the biomass ofRhodotorula strain var.glutinis, during the stationary phase of growth and in non-proliferating conditions was assayed. When the cells were transferred to distilled water, the fraction of -carotene produced increased from 130 to 630 g per gram of dried cells. 相似文献
373.
The photomutagenicity of the furochromone khellin was tested in Ames Salmonella strains using 8-methoxypsoralen (8-MOP) and 4,5', 8-trimethylpsoralen (TMP) as positive controls. When khellin was assayed with strain TA1537, mutation induction was not detectable; in the same strain, an equitoxic dose (52-56% level of survival) of TMP (used at a concentration 12-fold lower than khellin and with a UVA dose 83-fold lower than that used with khellin) yielded an increase in revertants/plate 3-fold above the spontaneous background. In strain TA102, khellin plus UVA treatment yielded a 2-fold increase in revertants/plate above the spontaneous background (79% survival). 8-MOP, however, used at a concentration 8-fold lower than khellin with a UVA dose 13-fold lower than khellin, yielded an increase in revertants/plate about 14-fold above background (66% survival) in the same strain. These data show that khellin has a weak photomutagenic potential and, along with the previously reported low photogenotoxic potential in eukaryotic cell systems, support the notion that khellin may be safer than bifunctional psoralens for clinical use. 相似文献
374.
Renato Bareggi Vittorio Grill Marina Zweyer Paola Narducci Alberto M. Martelli 《Cell and tissue research》1995,280(3):617-625
Using isoenzyme-specific antisera, we have studied the distribution of protein kinase C isoforms in fetal mouse organs at the developmental age of 17 days. Two different sets of antibodies, produced by different manufacturers, were employed in this study. The specificity of the antisera was tested by immunoblotting experiments using whole fetal mouse extracts. Immunohistochemistry was carried out by means of an alkaline phosphatase-conjugated secondary antibody. Analysis of fetal mouse longitudinal cryostat sections stained with the antibodies demonstrated a distinct distribution of protein kinase C isoforms in the tissues. Protein kinase C- and C-I were present in all tissues examined, whereas the C-II isoform was absent in the lung and the liver. Protein kinase C- was identified in brain, spinal ganglia, and adrenal gland. The C- isoenzyme was abundantly expressed in spinal ganglia and in the smooth muscle cells of the bronchial wall. Antisera to C- and C- isoforms heavily stained liver, kidney, and spinal ganglia, whereas the C- isozyme was mainly detected in brain, stomach and kidney. Thus, protein kinase C-, C-I, C-II, C-, C- and C- were the isoforms present in many of the organs investigated. The two sets of antibodies gave slightly different results that might be ascribed to the different epitopes recognized by the antisera. One set of antisera was employed to investigate the distribution of the isoforms in selected organs from an earlier developmental age (15 days) and from adult animals. Both qualitative and quantitative differences were seen in comparison with the same organs from a 17-day fetus. 相似文献
375.
Luca M. Neri Marina Zweyer Elisabetta Falcieri Roberta Bortul A. M. Martelli 《Histochemistry and cell biology》1997,108(6):525-536
The nuclear scaffold or matrix is a mainly proteinaceous structure thought to act as a nucleoskeleton determining the higher
order organization of eukaryotic chromatin. These structures are prepared from isolated nuclei by a series of extraction steps
involving the use of ionic detergents or high salt, and restriction enzymes or non-specific nucleases to remove chromatin
and other loosely bound components. Since these treatments are harsh and unphysiological, the question remains open as to
whether or not these structures, isolated in vitro, correspond to a nucleoskeleton existing in vivo. Recently, it has been
demonstrated that the majority of nuclear matrix proteins are involved in RNA metabolism. In this study we have employed a
morphological approach involving the use of confocal laser scanning microscopy and indirect immunofluorescence techniques
to analyze whether two widely employed methods to prepare the nuclear scaffold or matrix can maintain the spatial distribution
of two polypeptides involved in RNA metabolism, i.e., a 105-kDa component of spliceosomes and a ribonucleoprotein antigen.
We demonstrate that the localization of these polypeptides changes, in some cases dramatically, in the final nucleoskeletal
structures when compared with intact cells. Only when isolated nuclei were stabilized in vitro with the cross-linking agent
sodium tetrathionate (NaTT) prior to extraction with 2 M NaCl and DNase I digestion, were the immunofluorescent patterns displayed
by the nuclear matrix indistinguishable from those detected in intact cells. These results emphasize the usefulness of NaTT
in studying putative nucleoskeletal structures, but also show that the methods currently employed to prepare the nuclear scaffold
or matrix may create in vitro artifacts.
Accepted: 12 May 1997 相似文献
376.
Silvio Parodi Pia Carlo Antonietta Martelli Maurizio Taningher Renata Finollo Mauro Pala Walter Giaretti 《Journal of molecular biology》1981,147(4):501-521
A new oscillating crucible viscometer, having a U-shaped circular channel, is described. The damping coefficient δ is lowered by an increase of the viscosity η. The instrument described here allows the solution to come in contact with inert plastic only. At all steps of its preparation and during viscosity measurements, giant DNA from rat liver nuclei was maintained at shear stresses around 10?4 dynes cm?2. Viscosity was studied as a function of surface tension, DNA concentration and shear stress. It was found that under our experimental conditions it was possible to obtain meaningful values for reduced viscosity, ηred, practically identical to intrinsic viscosity [η]. Rat liver nuclei are incubated in an alkaline lysing solution (pH 12.5; 22 °C): they are lysed immediately and the released DNA starts to uncoil. The viscosity of solutions of this giant DNA increases very slowly with time, reaching a maximum only after about ten hours. The process was accelerated by single-stranded breaks arising from methylation of DNA in vivo with dimethylnitrosamine. It was found that the time of DNA disentanglement was sensitive to an exceedingly small number of breaks. We think that we were able to measure molecular weights around the length of the single strand of an average chromosome (Mn 5 × 1010). An empirical relation between molecular weight and reduced viscosity after complete disentanglement was also established, as a linear log-log plot, covering a molecular weight range between 108 and 2.5 × 1010. It is suggested that the viscosimetric evaluation of DNA disentanglement is probably the most sensitive method for studying DNA damage induced “in vivo” by chemical carcinogens. 相似文献
377.
Cacao beans must be subjected to fermentation before they are used in making chocolate, and their commercial value is related to a proper procedure. Saccharomyces rosei, Hansenula anomala, Pichia fermentans, Pichia membranaefaciens, and Trichosporon cutaneum were found in fermenting cacao beans. All species isolated during the investigation grew on cacao pulp, but only S. rosei, H. anomala, and P. fermentans exhibited fermenting capacity on the sugars of cacao pulp. Species of the genus Saccharomyces were identified as the agents responsible for the alcoholic phase of the cacao fermentation. 相似文献
378.
M Vitale A Matteucci L Manzoli L Rodella A R Mariani G Zauli M Falconi A M Billi A M Martelli R S Gilmour L Cocco 《FASEB journal》2001,15(10):1789-1791
379.
A model of the carbohydrate recognition domain CRD, residues 111-245, of
hamster galectin-3 has been made using homology modeling and dynamics
minimization methods. The model is based on the known x-ray structures of
bovine galectin-1 and human galectin-2. The oligosaccharides
NeuNAc-alpha2,3-Gal-beta1,4-Glc and GalNAc-alpha1, 3-
[Fuc-alpha1,2]-Gal-beta1,4-Glc, known to be specific high-affinity ligands
for galectin-3, as well as lactose recognized by all galectins were docked
in the galectin-3 CRD model structure and a minimized binding conformation
found in each case. These studies indicate a putative extended
carbohydrate-binding subsite in the hamster galectin- 3 involving Arg139,
Glu230, and Ser232 for NeuNAc-alpha2,3-; Arg139 and Glu160 for
fucose-alpha1,2-; and Arg139 and Ile141 for GalNAc-alpha1,3- substituents
on the primary galactose. Each of these positions is variable within the
whole galectin family. Two of these residues, Arg139 and Ser232, were
selected for mutagenesis to probe their importance in this newly identified
putative subsite. Residue 139 adopts main-chain dihedral angles
characteristic of an isolated bridge structural feature, while residue 232
is the C-terminal residue of beta- strand-11, and is followed immediately
by an inverse gamma-turn. A systematic series of mutant proteins have been
prepared to represent the residue variation present in the aligned
sequences of galectins-1, - 2, and -3. Minimized docked models were
generated for each mutant in complex with NeuNAc-alpha2,3-Gal-beta1,4-Glc,
GalNAc-alpha1, 3-[Fuc- alpha1,2]-Gal-beta1,4- Glc, and Gal-beta1,4-Glc.
Correlation of the computed protein-carbohydrate interaction energies for
each lectin- oligosaccharide pair with the experimentally determined
binding affinities for fetuin and asialofetuin or the relative potencies of
lactose and sialyllactose in inhibiting binding to asiolofetuin is
consistent with the postulated key importance of Arg139 in recognition of
the extended sialylated ligand.
相似文献
380.
Souto FJ Fontes CJ Martelli CM Turchi MD Martins RM Andrade AL 《Memórias do Instituto Oswaldo Cruz》1999,94(6):719-723
A community-based random survey was conducted in a southern Brazilian Amazonian county aiming to investigate hepatitis C virus (HCV) infection prevalence and the association of demographic variables and lifestyle behaviours. Seven hundred eighty individuals were serologically screened with a third generation enzyme-linked immunosorbent assay to detect anti-HCV antibodies between 1994/1995. Positive samples were retested for confirmation with a line immunoassay (LIA, Inno-LIA HCV Ab III). Most of these subjects were low income and came from southern Brazilian states (65.8). Two point four percent (IC 95% 1.2%- 4.6%) of the subjects had LIA-confirmed anti-HCV antibodies reactivity. The age-specific prevalence of HCV antibodies slightly increased with age, with the highest prevalence after the age of 40 years. The results of multivariate analysis indicate a strong association between HCV antibodies and previous surgery and history of intravenous drug use. There were no apparent association with gender, hepatitis B virus markers, blood transfusion, and sexual activity. Mean time living in Amazon did not differ between confirmed and negative anti-HCV individuals. The present data point out an intermediate endemicity of HCV infection among this immigrant community to the Amazon region and that few HCV infected participants presented known risk factors. 相似文献