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71.
Neuromodulin (P-57, GAP-43, B-50, F-1) is a neurospecific calmodulin binding protein that is phosphorylated by protein kinase C. Phosphorylation by protein kinase C has been shown to abolish the affinity of neuromodulin for calmodulin [Alexander, K. A., Cimler, B. M., Meier, K. E., & Storm, D. R. (1987) J. Biol. Chem. 262, 6108-6113], and we have proposed that the concentration of free CaM in neurons may be regulated by phosphorylation and dephosphorylation of neuromodulin. The purpose of this study was to identify the protein kinase C phosphorylation site(s) in neuromodulin using recombinant neuromodulin as a substrate. Toward this end, it was demonstrated that recombinant neuromodulin purified from Escherichia coli and bovine neuromodulin were phosphorylated with similar Km values and stoichiometries and that protein kinase C mediated phosphorylation of both proteins abolished binding to calmodulin-Sepharose. Recombinant neuromodulin was phosphorylated by using protein kinase C and [gamma-32P]ATP and digested with trypsin, and the resulting peptides were separated by HPLC. Only one 32P-labeled tryptic peptide was generated from phosphorylated neuromodulin. The sequence of this peptide was IQASFR. The serine in this peptide corresponds to position 41 of the entire protein, which is adjacent to or contained within the calmodulin binding domain of neuromodulin. A synthetic peptide, QASFRGHITRKKLKGEK, corresponding to the calmodulin binding domain with a few flanking residues, including serine-41, was also phosphorylated by protein kinase C. We conclude that serine-41 is the protein kinase C phosphorylation site of neuromodulin and that phosphorylation of this amino acid residue blocks binding of calmodulin to neuromodulin.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
72.
Sandra L. Tanner Elaine E. Storm †‡ George D. Bittner 《Journal of neurochemistry》1995,64(4):1491-1501
Abstract: Using video-enhanced microscopy and a pulse-radiolabeling paradigm, we show that proteins synthesized in the medial giant axon cell body of the crayfish ( Procambarus clarkii ) are delivered to the axon via fast (∼62 mm/day) and slow (∼0.8 mm/day) transport components. These data confirm that the medial giant axon cell body provides protein to the axon in a manner similar to that reported for mammalian axons. Unlike mammalian axons, the distal (anucleate) portion of a medial giant axon remains intact and functional for >7 months after severance. This axonal viability persists long after fast transport has ceased and after the slow wave front of radiolabeled protein has reached the terminals. These data are consistent with the hypothesis that another source (i.e., local glial cells) provides a significant amount of protein to supplement that delivered to the medial giant axon by its cell body. 相似文献
73.
74.
Romberg B Oussoren C Snel CJ Carstens MG Hennink WE Storm G 《Biochimica et biophysica acta》2007,1768(3):737-743
'Stealth' liposomes with a poly(ethylene glycol) (PEG) coating are frequently studied for drug delivery and diagnostic purposes because of their prolonged blood circulation kinetics. However, several recent reports have demonstrated that PEG-liposomes are rapidly cleared at single low lipid doses (<1 micromol/kg) and upon repeated administration (time interval between the injections 5 days-4 weeks). Recently, poly(amino acid)-based stealth liposome coatings have been developed as alternative to the PEG-coating. In this study, the pharmacokinetic behavior of liposomes coated with the poly(amino acid) poly(hydroxyethyl-l-asparagine) (PHEA) was evaluated at low lipid doses and upon repeated administration in rats. Blood circulation times and hepatosplenic localization of PHEA-liposomes were assessed after intravenous injection. When administered at a dose of 0.25 micromol/kg or less, PHEA-liposomes showed significantly longer blood circulation times than PEG-liposomes. A second dose of PHEA-liposomes 1 week after the first injection was less rapidly cleared from the circulation than a second dose of PEG-liposomes. Although the mechanisms behind these observations are still not clear yet, the use of PHEA-liposomes appears beneficial when single low lipid doses and/or repeated dosing schedules are being applied. 相似文献
75.
M L Corvo O C Boerman W J Oyen L Van Bloois M E Cruz D J Crommelin G Storm 《Biochimica et biophysica acta》1999,1419(2):325-334
Rheumatoid arthritis (RA) is a prevalent and debilitating autoimmune disease that affects the joints. RA is characterized by an infiltration of the affected joint by blood-derived cells. In response to activation, these cells generate reactive oxygen species, resulting in an oxidative stress situation. One approach to counteract this oxidative stress situation is the use of antioxidants as therapeutic agents. The free radical scavenger enzyme superoxide dismutase (SOD) may be used as a therapeutic agent in rheumatoid arthritis, but its rapid elimination from the circulation is a major limitation. Targeted delivery of SOD may overcome this limitation. In this study, the utility of PEGylated liposomes (PEG-liposomes) for targeting SOD to arthritic sites was explored. The targeting of SOD to arthritic sites following intravenous administration of both PEG-liposomes and positively charged liposomes lacking PEG but containing stearylamine (SA-liposomes) in rats with adjuvant arthritis was studied. At 24 h post injection, the blood levels of long circulating liposomes with a mean size of 0.11 micrometer and 0.20 micrometer were 8- and 3-fold higher, respectively, as compared to the SA-liposomes. The majority of SOD administered in liposomal form remains within the liposomes when they circulate in the bloodstream. The highest target uptake was observed with PEG-liposomes with a mean size of 0.11 micrometer and the lowest uptake with the SA-liposomes. These results demonstrate that SOD can be targeted to inflamed sites most efficiently via small-sized PEG-liposomes. Small-sized PEG-coated liposomes are to be preferred if prolonged circulation and enhanced localization of SOD at arthritic sites are desired. 相似文献
76.
A new opecoelid trematode is reported from fishes of the Lethrinidae, Lutjanidae and Nemipteridae off Lizard Island on the northern Great Barrier Reef, Australia. The new species keys to Neolebouria Gibson, 1976 and shows strong similarity to several species of that genus, but is not consistent with the type-species, N. georgiensis Gibson, 1976, or others known from temperate/polar and/or deep-sea fishes. The new species is also phylogenetically distant from N. lanceolata (Price, 1934) Reimer, 1987, the only representative of the genus for which molecular data are available. A new genus, Trilobovarium n. g., is proposed for the new species, T. parvvatis n. sp. Eight morphologically similar species, previously recognised as belonging to Neolebouria, from shallow-water, mostly tropical/subtropical fishes, are transferred to Trilobovarium: T. diacopae (Nagaty & Abdel Aal, 1962) n. comb.; T. ira (Yamaguti, 1940) n. comb.; T. khalili (Ramadan, 1983) n. comb.; T. krusadaiense (Gupta, 1956) n. comb.; T. lineatum (Aken’Ova & Cribb, 2001) n. comb.; T. moretonense (Aken’Ova & Cribb, 2001) n. comb.; T. palauense (Machida, 2014) n. comb.; and T. truncatum (Linton, 1940) n. comb. Paramanteriella Li, Qiu & Zhang, 1988 is resurrected for five species of Neolebouria with a post-bifurcal genital pore: P. cantherini Li, Qiu & Zhang, 1988; P. capoori (Jaiswal, Upadhyay, Malhotra, Dronen & Malhotra, 2014) n. comb.; P. confusa (Overstreet, 1969) n. comb.; P. leiperi (Gupta, 1956) n. comb.; and P. pallenisca (Shipley & Hornell, 1905) n. comb. Neolebouria georgenascimentoi Bray, 2002, a species with an exceptionally long cirrus-sac, is transferred to Bentholebouria Andres, Pulis & Overstreet, 2004 as B. georgenascimentoi (Bray, 2002) n. comb., and N. maorum (Allison, 1966) Gibson 1976, an unusual species known from cephalopods, is designated a species incertae sedis. Eleven species are retained in a revised concept of Neolebouria. 相似文献
77.
Kamishina H Farese JP Storm JA Cheeseman JA Clemmons RM 《In vitro cellular & developmental biology. Animal》2008,44(10):472-479
Bone marrow stromal cells (BMSCs) have gained considerable attention as a potential source for cell transplantation therapies
for a variety of diseases due to their accessibility, proliferative capacity, and multilineage differentiation properties.
Canine BMSCs have been shown to contribute to regeneration of osseous tissues, but knowledge about their biology is currently
limited. In the present study, we investigated the frequency of adult canine BMSCs in bone marrow, morphological features,
growth kinetics, and osteogenic as well as adipogenic differentiation properties in vitro. Our data suggest that adult canine
bone marrow contains approximately one BMSC in every 2.38 × 104 bone marrow mononucleated cells (0.0042 ± 0.0019%, n = 5). Primary BMSC cultures consisted of morphologically heterogeneous adherent cell populations from which spindle-shaped
cells grew and became the predominant cell type. Growth kinetics patterns were dependent on the initial cell seeding densities,
resulting in the highest fold increase at lower cell density. In the presence of osteogenic and adipogenic inducers, primary
BMSCs underwent morphological and phenotypic changes characteristic of osteogenic and adipogenic differentiation, respectively.
This study provides insights into basic characterization of adult canine BMSCs. 相似文献
78.
The drug efflux pump P-glycoprotein (P-gp) (ABCB1) confers multidrug resistance, a major cause of failure in the chemotherapy of tumours, exacerbated by a shortage of potent and selective inhibitors. A high throughput assay using purified P-gp to screen and characterise potential inhibitors would greatly accelerate their development. However, long-term stability of purified reconstituted ABCB1 can only be reliably achieved with storage at −80 °C. For example, at 20 °C, the activity of ABCB1 was abrogated with a half-life of <1 day. The aim of this investigation was to stabilise purified, reconstituted ABCB1 to enable storage at higher temperatures and thereby enable design of a high throughput assay system. The ABCB1 purification procedure was optimised to allow successful freeze drying by substitution of glycerol with the disaccharides trehalose or maltose. Addition of disaccharides resulted in ATPase activity being retained immediately following lyophilisation with no significant difference between the two disaccharides. However, during storage trehalose preserved ATPase activity for several months regardless of the temperature (e.g. 60% retention at 150 days), whereas ATPase activity in maltose purified P-gp was affected by both storage time and temperature. The data provide an effective mechanism for the production of resilient purified, reconstituted ABCB1. 相似文献
79.
Atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information
is needed on interactive CO2 and O3 effects on roots, particularly fine-root life span, a critical demographic parameter and determinant of soil C and N pools
and cycling rates. We conducted a study in which ponderosa pine (Pinus ponderosa) seedlings were exposed to two levels of CO2 and O3 in sun-lit controlled-environment mesocosms for 3 years. Minirhizotrons were used to monitor individual fine roots in three
soil horizons every 28 days. Proportional hazards regression was used to analyze effects of CO2, O3, diameter, depth, and season of root initiation on fine-root survivorship. More fine roots were produced in the elevated
CO2 treatment than in ambient CO2. Elevated CO2, increasing root diameter, and increasing root depth all significantly increased fine-root survivorship and median life span.
Life span was slightly, but not significantly, lower in elevated O3, and increased O3 did not reduce the effect of elevated CO2. Median life spans varied from 140 to 448 days depending on the season of root initiation. These results indicate the potential
for elevated CO2 to increase the number of fine roots and their residence time in the soil, which is also affected by root diameter, root
depth, and phenology. 相似文献
80.
It is common to portray conservative and liberal Protestant denominations as “strong” and “weak” on the basis of indices such
as church attendance. Alternatively, they can be regarded as qualitatively different cultural systems that coexist in a multiple-niche
environment. We integrate these two perspectives with a study of American teenagers based on both one-time survey information
and the experience sampling method (ESM), which records individual experience on a moment-by-moment basis. Conservative Protestant
youth were found to be more satisfied, family-oriented, and sociable than liberal Protestant youth, but also more dependent
on their social environment, which is reflected in a deterioration of their mood when they are alone. Liberal Protestant youth
appear to have internalized values that remain constant whether in the presence or absence of others. We relate these results
to the social scientific literature on liberalism and conservatism and to evolutionary theory as a framework for explaining
cultural systems as adaptations to multiple-niche environments.
相似文献
David Sloan WilsonEmail: |