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21.
Britten CJ; van den Eijnden DH; McDowell W; Kelly VA; Witham SJ; Edbrooke MR; Bird MI; de Vries T; Smithers N 《Glycobiology》1998,8(4):321-327
The alpha3 fucosyltransferase, FucT-VII, is one of the key
glycosyltransferases involved in the biosynthesis of the sialyl Lewis X
(sLex) antigen on human leukocytes. The sialyl Lewis X antigen
(NeuAcalpha(2-3)Galbeta(1-4)[Fucalpha(1-3)]GlcNAc-R) is an essential
component of the recruitment of leukocytes to sites of inflammation,
mediating the primary interaction between circulating leukocytes and
activated endothelium. In order to characterize the enzymatic properties of
the leukocyte alpha3 fucosyltransferase FucT-VII, the enzyme has been
expressed in Trichoplusia ni insect cells. The enzyme is capable of
synthesizing both sLexand sialyl-dimeric-Lexstructures in vitro , from
3'-sialyl-lacNAc and VIM-2 structures, respectively, with only low levels
of fucose transfer observed to neutral or 3'-sulfated acceptors. Studies
using fucosylated NeuAcalpha(2-3)-(Galbeta(1- 4)GlcNAc)3-Me acceptors
demonstrate that FucT-VII is able to synthesize both di-fucosylated and
tri-fucosylated structures from mono- fucosylated precursors, but
preferentially fucosylates the distal GlcNAc within a polylactosamine
chain. Furthermore, the rate of fucosylation of the internal GlcNAc
residues is reduced once fucose has been added to the distal GlcNAc. These
results indicate that FucT-VII is capable of generating complex selectin
ligands, in vitro , however the order of fucose addition to the lactosamine
chain affects the rate of selectin ligand synthesis.
相似文献
22.
EMMA L. WRIGHT COLIN R. BLACK ALEXANDER W. CHEESMAN TREVOR DRAGE DAVID LARGE BENJAMIN L. TURNER SOFIE SJÖGERSTEN 《Global Change Biology》2011,17(9):2867-2881
Tropical peatlands play an important role in the global carbon cycling but little is known about factors regulating carbon dioxide (CO2) and methane (CH4) fluxes from these ecosystems. Here, we test the hypotheses that (i) CO2 and CH4 are produced mainly from surface peat and (ii) that the contribution of subsurface peat to net C emissions is governed by substrate availability. To achieve this, in situ and ex situ CO2 and CH4 fluxes were determined throughout the peat profiles under three vegetation types along a nutrient gradient in a tropical ombrotrophic peatland in Panama. The peat was also characterized with respect to its organic composition using 13C solid state cross‐polarization magic‐angle spinning nuclear magnetic resonance spectroscopy. Deep peat contributed substantially to CO2 effluxes both with respect to actual in situ and potential ex situ fluxes. CH4 was produced throughout the peat profile with distinct subsurface peaks, but net emission was limited by oxidation in the surface layers. CO2 and CH4 production were strongly substrate‐limited and a large proportion of the variance in their production (30% and 63%, respectively) was related to the quantity of carbohydrates in the peat. Furthermore, CO2 and CH4 production differed between vegetation types, suggesting that the quality of plant‐derived carbon inputs is an important driver of trace gas production throughout the peat profile. We conclude that the production of both CO2 and CH4 from subsurface peat is a substantial component of the net efflux of these gases, but that gas production through the peat profile is regulated in part by the degree of decomposition of the peat. 相似文献
23.
Neomi Moav Nechama I. Smorodinsky Ben-Ami Balin Isaac P. Witz 《Cancer immunology, immunotherapy : CII》1995,12(3):217-224
Summary Monoclonal antibodies were produced by fusing NS1/1 myeloma cells with splenocytes from A. BY mice bearing syngeneic polyoma virus-induced SEYF-a tumors.From six separate fusion experiments 514 hybridomas were obtained, 45 of which were found to secrete SEYF-a-binding antibodies. The binding patterns of antibodies secreted by eight hybridomas to a panel of tumor cells and to normal mouse fibroblasts were analyzed by means of an indirect radioimmunoassay. Seven hybridomas were found to secrete antibodies that bound to all cell lines tested. This indicated that certain SEYF-a-associated antigens are widely distributed on a variety of seemingly nonrelated tumor cells.One hybridoma secreted antibodies that exhibited a high binding activity to SEYF-a cells, a low binding activity to two members of the tumor panel, and none at all against most of its constituents, including normal fibroblasts. The results of the binding experiments were further supported by absorption experiments.A subclass analysis of the immunoglobulins secreted by the various hybridomas revealed that three clones secreted IgG1; one clone secreted IgM; and three clones secreted IgG2a. Polyacrylamide gel electrophoresis of two of the secreted antibodies indicated a high degree of homogeneity of the heavy and the light chain of the corresponding antibodies, as would be expected from monoclonal products.The results of this study demonstrate the feasibility of obtaining anti-tumor monoclonal antibodies from tumor bearers, representing the immune response of the tumor bearer against antigens associated with his syngeneic tumor. 相似文献
24.
Goring DR Banks P Fallis L Baszczynski CL Beversdorf WD Rothstein SJ 《The Plant journal : for cell and molecular biology》1992,2(6):999-1003
We have previously described a developmentally regulated mRNA in maize that accumulates in mature embryos and is involved in a variety of stress responses in the plant. The sequence of the encoded 16 kDa protein (MA16) predicts that it is an RNA-binding protein, since it possesses a ribonucleoprotein consensus sequence-type RNA-binding domain (CS-RBD). To assess the predicted RNA binding property of the protein and as a starting point to characterize its function we have used ribohomopolymer-binding assays. Here we show that the MA16-encoded protein binds preferentially to uridine- and guanosine-rich RNAs. In light of these results a likely role for this protein in RNA metabolism during late embryogenesis and in the stress response is discussed. 相似文献
25.
M Eser M Kement S Balin C Coskun U Kefeli M Gumus YE Altuntas N Kurt A Mayadagli 《World journal of surgical oncology》2012,10(1):180
ABSTRACT: BACKGROUND: The purpose of this study was to investigate plasma levels of thrombin activatable fibrinolysis inhibitor (TAFI) and TAFI's relationship with coagulation markers (prothrombin fragment 1 + 2) in gastric cancer patients. METHODS: Thirty-three patients with gastric adenocarcinoma and 29 healthy control subjects were prospectively enrolled in the study. Patients who had a history of secondary malignancy, thrombosis related disease, oral contraceptive use, diabetes mellitus, chronic renal failure or similar chronic metabolic disease were excluded from the study. A fasting blood sample was drawn from patients to determine the plasma levels of TAFI and Prothrombin Fragment 1 + 2 (F 1 + 2). In addition, data on patient age, sex, body mass index (BMI) and stage of disease were recorded. The same parameters, except stage of disease, were also recorded for the control group. Subsequently, we assessed the difference in the levels of TAFI and F 1 + 2 between the patient and control groups. Moreover, we investigated the relation of TAFI and F 1 + 2 levels with age, sex, BMI and stage of disease in the gastric cancer group. RESULTS: There were no statistical differences in any demographic variables (age, gender and BMI) between the groups (Table 1). The mean plasma TAFI levels of the gastric cancer group (69.4 [PLUS-MINUS SIGN] 33.1) and control group (73.3 [PLUS-MINUS SIGN] 27.5) were statistically similar (P = 0.62). The mean plasma F 1 + 2 level in the gastric cancer group was significantly higher than for those in the control group (549.7 [PLUS-MINUS SIGN] 325.3 vs 151.9 [PLUS-MINUS SIGN] 67.1, respectively; P < 0.001). In the gastric cancer group, none of the demographic variables (age, gender and BMI) were correlated with either TAFI or F 1 + 2 levels. Also, no significant associations were found between the stage of the cancer and either TAFI or F 1 + 2 levels. CONCLUSION: In our study, TAFI levels of gastric cancer patients were similar to healthy subjects. The results of our study suggest that TAFI does not play a role in pathogenesis of the hypercoagulable state in gastric cancer patients. 相似文献
26.
In spite of the increasing application of DNA fingerprinting to natural
populations and to the genetic identification of humans, explicit methods
for estimation of basic population genetic parameters from DNA
fingerprinting data have not been developed. Contributing to this omission
is the inability to determine, for multilocus fingerprinting probes,
relatively important genetic information, such as the number of loci, the
number of alleles, and the distribution of these alleles into specific
loci. One of the most useful genetic parameters that could be derived from
such data would be the average heterozygosity, which has traditionally been
employed to measure the level of genetic variation within populations and
to compare genetic variation among different loci. We derive here explicit
formulas for both the estimation of average heterozygosity at multiple
hypervariable loci and a maximum value for this estimate. These estimates
are based upon the DNA restriction-pattern matrices that are typical for
fingerprinting studies of humans and natural populations. For several
empirical data sets from our laboratory, estimates of average and maximal
heterozygosity are shown to be relatively close to each other. Furthermore,
variances of these statistics based on simulation studies are relatively
small. These observations, as well as consideration of the effect of
missing alleles and alternate numbers of loci, suggest that the average
heterozygosity can be accurately estimated using phenotypic DNA fingerprint
patterns, because this parameter is relatively insensitive to the lack of
certain genetic information.
相似文献
27.
28.
Hayley M Bennett Hoi Ping Mok Effrossyni Gkrania-Klotsas Isheng J Tsai Eleanor J Stanley Nagui M Antoun Avril Coghlan Bhavana Harsha Alessandra Traini Diogo M Ribeiro Sascha Steinbiss Sebastian B Lucas Kieren SJ Allinson Stephen J Price Thomas S Santarius Andrew J Carmichael Peter L Chiodini Nancy Holroyd Andrew F Dean Matthew Berriman 《Genome biology》2014,15(11)
29.
Background
Association mapping using abundant single nucleotide polymorphisms is a powerful tool for identifying disease susceptibility genes for complex traits and exploring possible genetic diversity. Genotyping large numbers of SNPs individually is performed routinely but is cost prohibitive for large-scale genetic studies. DNA pooling is a reliable and cost-saving alternative genotyping method. However, no software has been developed for complete pooled-DNA analyses, including data standardization, allele frequency estimation, and single/multipoint DNA pooling association tests. This motivated the development of the software, 'PDA' (Pooled DNA Analyzer), to analyze pooled DNA data. 相似文献30.
Chien-Hsing Lin Ling-Hui Li Sheng-Feng Ho Tzu-Po Chuang Jer-Yuarn Wu Yuan-Tsong Chen Cathy SJ Fann 《BMC genetics》2008,9(1):1-9