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41.
Hendrikus J. Laanbroek Paul L. E. Bodelier Saskia Gerards 《Archives of microbiology》1994,161(2):156-162
Chemolithotrophic ammonium- and nitrite-oxidizing bacteria are dependent on the presence of oxygen for the production of nitrite and nitrate, respectively. In oxygen-limited environments, they have to compete with each other as well as with other organotrophic bacteria for the available oxygen. The outcome of the competition will be determined by their specific affinities for oxygen as well as by their population sizes. The effect of mixotrophic growth by the nitrite-oxidizing Nitrobacter hamburgensis on the competition for limiting amounts of oxygen was studied in mixed continuous culture experiments with the ammonium-oxidizing Nitrosomonas europaea at different levels of oxygen concentrations.The specific affinity for oxygen of N. europaea was in general higher than of N. hamburgensis. In transient state experiments, when oxic conditions were switched to anoxic, N. hamburgensis was washed out and nitrite accumulated. However, grown at low oxygen concentration, the specific affinity for oxygen of N. hamburgensis increased and became as great as that of N. europaea. Due to its larger population size, the nitrite-oxidizing bacterium became the better competitor for oxygen and ammonium accumulated in the fermentor. It is suggested that continuously oxygen-limited environments present a suitable ecological niche for the nitrite-oxidizing N. hamburgensis. 相似文献
42.
The glucose transport system of the hyperthermophilic anaerobic bacterium Thermotoga neapolitana 下载免费PDF全文
The glucose transport system of the extremely thermophilic anaerobic bacterium Thermotoga neapolitana was studied with the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DOG). T. neapolitana accumulated 2-DOG against a concentration gradient in an intracellular free sugar pool that was exchangeable with external source of energy, such as pyruvate, and was inhibited by arsenate and gramicidin D. There was no phosphoenolpyruvate-dependent phosphorylation of glucose, 2-DOG, or fructose by cell extracts or toluene-treated cells, indicating the absence of a phosphoenolpyruvate:sugar phosphotransferase system. These data indicate that D-glucose is taken up by T. neapolitana via an active transport system that is energized by an ion gradient generated by ATP, derived from substrate-level phosphorylation. 相似文献
43.
Detection and characterization of fungal infections of Ammophila arenaria (marram grass) roots by denaturing gradient gel electrophoresis of specifically amplified 18s rDNA. 总被引:4,自引:0,他引:4 下载免费PDF全文
Marram grass (Ammophila arenaria L.), a sand-stabilizing plant species in coastal dune areas, is affected by a specific pathosystem thought to include both plant-pathogenic fungi and nematodes. To study the fungal component of this pathosystem, we developed a method for the cultivation-independent detection and characterization of fungi infecting plant roots based on denaturing gradient gel electrophoresis (DGGE) of specifically amplified DNA fragments coding for 18S rRNA (rDNA). A nested PCR strategy was employed to amplify a 569-bp region of the 18S rRNA gene, with the addition of a 36-bp GC clamp, from fungal isolates, from roots of test plants infected in the laboratory, and from field samples of marram grass roots from both healthy and degenerating stands from coastal dunes in The Netherlands. PCR products from fungal isolates were subjected to DGGE to examine the variation seen both between different fungal taxa and within a single species. DGGE of the 18S rDNA fragments could resolve species differences from fungi used in this study yet was unable to discriminate between strains of a single species. The 18S rRNA genes from 20 isolates of fungal species previously recovered from A. arenaria roots were cloned and partially sequenced to aid in the interpretation of DGGE data. DGGE patterns recovered from laboratory plants showed that this technique could reliably identify known plant-infecting fungi. Amplification products from field A. arenaria roots also were analyzed by DGGE, and the major bands were excised, reamplified, sequenced, and subjected to phylogenetic analysis. Some recovered 18S rDNA sequences allowed for phylogenetic placement to the genus level, whereas other sequences were not closely related to known fungal 18S rDNA sequences. The molecular data presented here reveal fungal diversity not detected in previous culture-based surveys. 相似文献
44.
Mike Gerards Bianca van den Bosch Chantal Calis Kees Schoonderwoerd Klaartje van Engelen Marina Tijssen René de Coo Anneke van der Kooi Hubert Smeets 《Mitochondrion》2010,10(5):510-515
Hereditary ataxias are genetic disorders characterized by uncoordinated gait and often poor coordination of hands, speech, and eye movements. Frequently, atrophy of the cerebellum occurs. Many ataxias are autosomal dominant, but autosomal recessive (AR) disease occurs as well. Homozygosity mapping in a consanguineous family with three affected children with progressive cerebellar ataxia and atrophy revealed a candidate locus on chromosome 1, containing the CABC1/ADCK3 (the chaperone, ABC1 activity of bc1 complex homologue) gene. CABC1/ADCK3 is the homologue of the yeast Coq8 gene, which is involved in the ubiquinone biosynthesis pathway. Mutation analysis of this gene showed a homozygous nonsense mutation (c.1042C > T, p.R348X). Eight additional patients with AR cerebellar ataxia and atrophy were screened for mutations in the CABC1/ADCK3 gene. One patient was compound heterozygous for the same c.1042C > T mutation and a second nonsense mutation (c.1136T > A, p.L379X). Both mutations created a premature stop codon, triggering nonsense mediated mRNA decay as the pathogenic mechanism. We found no evidence of a Dutch founder for the c.1042C > T mutation in AR ataxia. We report here the first nonsense mutations in CABC1 that most likely lead to complete absence of a functional CABC1 protein. Our results indicate that CABC1 is an important candidate for mutation analysis in progressive cerebellar ataxia and atrophy on MRI to identify those patients, who may benefit from CoQ10 treatment. 相似文献
45.
Serum from 88 pregnant sows and gilts was sampled 24 and 28 days after their first insemination or mating day. The oestrone sulphate (E1S) concentration in the samples was assessed with a commercially available radioimmunoassay kit modified for use with swine serum. The first aim was to test whether it was possible to predict litters of total number <10 piglets at term. The second aim was to compare the use of day 24 or day 28 samples, or of both, in this prediction. 相似文献
46.
Clinical expression of Leber hereditary optic neuropathy is affected by the mitochondrial DNA-haplogroup background 下载免费PDF全文
Hudson G Carelli V Spruijt L Gerards M Mowbray C Achilli A Pyle A Elson J Howell N La Morgia C Valentino ML Huoponen K Savontaus ML Nikoskelainen E Sadun AA Salomao SR Belfort R Griffiths P Man PY de Coo RF Horvath R Zeviani M Smeets HJ Torroni A Chinnery PF 《American journal of human genetics》2007,81(2):228-233
Leber hereditary optic neuropathy (LHON) is due primarily to one of three common point mutations of mitochondrial DNA (mtDNA), but the incomplete penetrance implicates additional genetic or environmental factors in the pathophysiology of the disorder. Both the 11778G-->A and 14484T-->C LHON mutations are preferentially found on a specific mtDNA genetic background, but 3460G-->A is not. However, there is no clear evidence that any background influences clinical penetrance in any of these mutations. By studying 3,613 subjects from 159 LHON-affected pedigrees, we show that the risk of visual failure is greater when the 11778G-->A or 14484T-->C mutations are present in specific subgroups of haplogroup J (J2 for 11778G-->A and J1 for 14484T-->C) and when the 3460G-->A mutation is present in haplogroup K. By contrast, the risk of visual failure is significantly less when 11778G-->A occurs in haplogroup H. Substitutions on MTCYB provide an explanation for these findings, which demonstrate that common genetic variants have a marked effect on the expression of an ostensibly monogenic mtDNA disorder. 相似文献
47.
JS Agerholm O Andersen MB Almskou C Bendixen J Arnbjerg GP Aamand US Nielsen F Panitz AH Petersen 《Acta veterinaria Scandinavica》2004,45(3):133
To investigate the congenital complex vertebral malformation syndrome (CVM) in Holstein calves, two breeding studies were
performed including 262 and 363 cows, respectively. Cows were selected from the Danish Cattle Database based on pedigree and
insemination records. Selected cows were progeny of sires with an established heterozygous CVM genotype and pregnant after
insemination with semen from another sire with heterozygous CVM genotype. Following calving the breeders should state, if
the calf was normal and was requested to submit dead calves for necropsy. In both studies, significantly fewer CVM affected
calves than expected were obtained; a finding probably reflecting extensive intrauterine mortality in CVM affected foetuses.
The findings illustrate increased intrauterine mortality as a major potential bias in observational studies of inherited disorders. 相似文献
48.
de Lathouder S Gerards AH Dijkmans BA Aarden LA 《Nucleosides, nucleotides & nucleic acids》2004,23(8-9):1089-1100
Methotrexate (MTX) and mycophenolic acid (MPA) are used in the clinic for their immunosuppressive properties. MTX is widely used for the treatment of rheumatoid arthritis (RA). MPA is used to prevent graft rejection and is now experimentally used in systemic lupus erythematosis and RA. It is known that both drugs interfere with DNA synthesis. However, the precise mechanism of action is still debated. We have analysed the effect of the drugs on cytokine production in whole blood during short cultures. The production of T-cell cytokines was inhibited by both drugs. MTX inhibits cytokine production because MTX induces apoptosis in activated T-cells. MPA inhibits cytokine production by preventing T-cells to progress to the S-phase of the cell cycle. Cytokine production by monocytes was slightly decreased by the drugs. The reason for this inhibition is not clear. These results indicate that T-cells are the main target cells of the immunosuppressive drugs MPA and MTX. 相似文献
49.
Ashraf A Helmy Mostafa A Hamad Ahmed M Aly Tahra Sherif Mostafa Hashem Dalia AH El-Sers Mohammad Semieka 《Annals of surgical innovation and research》2011,5(1):1-9
Background
Biliary tract reconstruction continues to be a challenging surgical problem. Multiple experimental attempts have been reported to reconstruct biliary defects with different materials and variable outcome. Our aim was to evaluate a new method for biliary reconstruction using an isolated pedicled gastric tube in a live animal trial and also to present the first clinical case.Methods
Seven mongrel dogs underwent biliary reconstruction using gastric tube harvested, completely separated from the greater curvature, and based on a vascularized pedicle with the right gastroepiploic vessels. The tube was interposed between the common bile duct (CBD) and the duodenum. Postoperative mortality, morbidity, liver functions, gross and microscopic histological picture were assessed. The first clinical case was also presented where, in a patient with post-cholecystectomy biliary injury, an isolated pedicled gastric tube was interposed between the proximal and distal ends of the CBD.Results
One dog did not recover from anesthesia and another one died postoperatively from septic peritonitis. Five dogs survived the procedure and showed uneventful course and no cholestasis. The mean anastomotic circumference was 4.8 mm (range 4-6) for CBD anastomosis and 6.2 mm (range 5-7) for duodenal anastomosis. Histologically, anastomotic sites showed good evidence of healing. In the first clinical case, the patient showed clinical and biochemical improvement. Endoscopic retrograde cholangiography was feasible and assured patent biliary anastomoses.Conclusion
In mongrel dogs, biliary reconstruction using pedicled gastric tube interposition between CBD and duodenum is feasible with satisfactory clinical results, anastomotic circumference and histological evidence of healing. The technique is also feasible in human and seems to be promising. 相似文献50.
Jo Moore Stephen AC Hawkins Anthony R Austin Timm Konold Robert B Green Ian W Blamire Ian Dexter Michael J Stack Melanie J Chaplin Jan PM Langeveld Marion M Simmons Yvonne I Spencer Paul R Webb Michael Dawson Gerald AH Wells 《BMC research notes》2011,4(1):1-13