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71.
The possibility to cultivate Lactococcus lactis in aqueous polymer two-phase system has been investigated. The phase system was made up of poly(ethylene imine) and (hydroxyethyl) cellulose. Long lag phases were needed for the microorganism to adapt to the polymer rich media. Cells favoured the (hydroxyethyl)cellulose rich top phase or they accumulated at the interface, while lactic acid showed affinity for the poly(ethylene imine) rich phase.Abbreviations PEG
poly(ethylene glycol)
- PEI
poly(ethylene imine)
- HEC
(hydroxyethyl)cellulose 相似文献
72.
Lactate dehydrogenase (LDH) was purified from beef heart homogenate by affinity precipitation. The protein purification was
integrated with nucleic acid removal and was done by precipitation of nucleic acids by addition of poly(ethylene imine) PEI
onto which a ligand, Cibacron blue, had been coupled. The yield of LDH after elution from the precipitate was 63%, the purification
factor 6.9 and the nucleic acid content was reduced by 98%. The capacity of the affinity polymer Cibacron blue-PEI is dependent
on the nucleic acid concentration in the homogenate. The beef heart homogenate had an unfavourable ratio of nucleic acids
to LDH. Precipitation with recirculated Cibacron blue-PEI, already complexed with some nucleic acids, improved the yield of
the enzyme to 74%. The loss of Cibacron blue-PEI, when recirculated, was less than 1% after each cycle.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
73.
74.
The C3 phenotype distribution was investigated in different age-groups among 2,078 voluntary blood donors between the ages of 20 and 65 years, in a group of unrelated babies and in a group of old healthy persons. A continuous increase in the C3F gene frequency with age was found among the blood donors varying from 0.1780 in the youngest age group (babies: 0.1585) to 0.2516 at the age of 50-55 years followed by a continuous decrease to a level of 0.1700 among the eldest donors (01718 among the old persons). In the age group 45-49 years the C3 distribution differed significantly from that in the adjoining age-groups (C3F = 0.1619). It is believed that the variations are brought about by selection of the blood donor population and a balanced polymorphism for the C3 system, possibly due to differences in the biological efficiency of the C3 variants in the complement sequence. 相似文献
75.
Molecular properties of the two isozymes expressed by the B allele at the red cell acid phosphatase locus (ACP1) have been studied to distinguish between possible mechanisms for their production. The difference in electric charge exhibited by the native isozymes was retained under denaturing conditions; the unfolded peptide chains renatured without conversion of one form to the other. Chromatographic analysis [thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC)] of tryptic digests showed 12 peptides common to both isozymes but also revealed 5 peptides unique to one isozyme and 3 (possibly 4) peptides unique to the other. These findings argue against both conformational isomerization and simple posttranslational modification as the mechanism of generation of the two isozymes. We suggest that the two isozymes are synthesized as discrete molecular entities. 相似文献
76.
Red cell esterase D (EsD) phenotypes were determined in a Danish population sample of 3,116 unrelated adults by starch-gel electrophoresis. A new phenotype was discovered, which appeared to be determined by the EsD1 allele and a new allele EsDCph. The gene frequencies observed were EsD1 = 0.9007, EsD2 = 0.0992, EsDCph = 0.0001. Investigation of 1,111 mother-child pairs and 59 families with 157 offspring added further support to the genetic model of two common alleles at an autosomal locus. The applicability of the EsD polymorphism to paternity testing was investigated on 960 cases of disputed paternity. An estimate of the EsD null allele frequency (0.001) in European populations was made on the basis of observations made on 5,864 mother/child combinations and 762 matings with 1,882 offspring. The influence of this allele on the reliability of exclusions of paternity was determined. 相似文献
77.
78.
In permeabilized lacrimal acinar cells, cyclic ADP-ribose (cADP-ribose) and inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) release Ca2+ in a dose dependent manner from distinct thapsigargin-sensitive Ca2+ pools. Ryanodine specifically blocks the Ca2+ response to cADP-ribose, whereas heparin strongly reduces the response to Ins(1,4,5)P3 application. GTP causes a rapid Ca2+ release by a ryanodine- and heparin-insensitive mechanism and potentiates Ins(1,4,5)P3 but not cADP-ribose evoked Ca2+ release. It is estimated that cADP-ribose can release 16 μmol Ca2+/I cells, whereas Ins(1,4,5)P3 can mobilize 55 μmol Ca2+/I cells. The results suggest that cADP-ribose and Ins(1,4,5)P3 release Ca2+ from distinct internal stores and that a third Ca2+ pool exists which can selectively interact with the Ins(1,4,5)P3-sensitive Ca2+ store by a GTP-mediated process. 相似文献
79.
T cell activation. II. Activation of human T lymphoma cells by cross-linking of their MHC class I antigens 总被引:2,自引:0,他引:2
The present work demonstrates that antibody-induced cross-linking of MHC class I antigens on Jurkat T lymphoma cells leads to a rise in intracellular calcium (Cai2+) and, in the presence of phorbol ester (PMA), to IL-2 production and IL-2 receptor expression. The rise in Cai2+ exhibited a profile very different from that obtained after anti-CD3 antibody-induced activation suggesting that activation signals are transduced differently after binding of anti-CD3 antibody and class I cross-linking, respectively. However, when Cai2+ was examined in individual Jurkat cells by means of a digital image processing system no differences were observed after cross-linking with anti-CD3 and anti-MHC class I antibodies, respectively. Two CD3-negative mutant lymphoma lines were nearly totally refractory to class I cross-linking. Taken together our results may indicate the existence of a functional linkage between the T cell receptor complex and MHC class I molecules. 相似文献