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1.
The influence of growth rate, the presence of acetate and variation in the dissolved oxygen concentration on the kinetics
of nitrite oxidation was studied in suspensions of intact cells of Nitrobacter winogradskyi and Nitrobacter hamburgensis. The cells were grown in nitrite-limited chemostats at different dilution rates under chemolithotrophic and mixotrophic conditions.
Growth of N. hamburgensis in continuous culture was dependent on the presence of acetate. Acetate hardly affected the maximal nitrite oxidation rate
per cell (V
max), but displayed a distinctly negative effect on the saturation constants for nitrite oxidation (K
m
) of both Nitrobacter species. This effect was reversible; when acetate was removed from the suspensions the K
m
-values for nitrite oxidation returned to their original values.
A reduction of the dissolved oxygen concentration from 100% to 18% air saturation slightly decreased the V
max of chemolithotrophically grown N. winogradskyi cells, whereas a 2.3 fold increase was observed with mixotrophically grown cells of N. hamburgensis. It is suggested that the large variation in K
m
encountered in field samples could be due to this observed phenotypic variability. The V
max per cell is not a constant, but apparently is dependent on growth rate and environmental conditions. This implies that potential
nitrite oxidation activity and numbers of cells are not necessarily related. Considering their kinetic characteristics, it
is unlikely that N. hamburgensis is able to compete succesfully with N. winogradskyi for limiting amounts of nitrite under mixotrophic conditions. However, at reduced partial oxygen tensions, N. hamburgensis may become the better competitor. 相似文献
2.
3.
David F Ten Cate Jolanda J Luime Nanno Swen Andreas H Gerards Mike H De Jager Natalja M Basoski Johanna MW Hazes Cees J Haagsma Johannes WG Jacobs 《Arthritis research & therapy》2013,15(1):R4
Introduction
Ultrasonography (US) might have an added value to clinical examination in diagnosing early rheumatoid arthritis (RA) and assessing remission of RA. We aimed to clarify the added value of US in RA in these situations performing a systematic review.Methods
A systematic literature search was performed for RA, US, diagnosis and remission. Methodological quality was assessed; the wide variability in the design of studies prohibited pooling of results.Results
Six papers on the added value of US diagnosing early RA were found, in which at least bilateral metacarpophalangeal (MCP), wrists and metatarsophalangeal (MTP) joints were scanned. Compared to clinical examination, US was superior with regard to detecting synovitis and predicting progression to persistent arthritis or RA. Eleven papers on assessing remission were identified, in which at least the wrist and the MCP joints of the dominant hand were scanned. Often US detected inflammation in patients clinically in remission, irrespective of the remission criteria used. Power Doppler signs of synovitis predicted X-ray progression and future flare in patients clinically in remission.Conclusions
US appears to have added value to clinical examination for diagnosing of RA when scanning at least MCP, wrist and MTP joints, and, when evaluating remission of RA, scanning at least wrist and MCP joints of the dominant hand. For both purposes primarily power Doppler US might be used since its results are less equivocal than those of greyscale US. 相似文献4.
Abstract A class of very potent nucleoside transport inhibitors is present in two molecular forms around physiological pH. We investigated whether the monoprotonated or the unionized species of these molecules binds to this camer protein with higher affinity. 相似文献
5.
Christopher I Keeling Macaire MS Yuen Nancy Y Liao T Roderick Docking Simon K Chan Greg A Taylor Diana L Palmquist Shaun D Jackman Anh Nguyen Maria Li Hannah Henderson Jasmine K Janes Yongjun Zhao Pawan Pandoh Richard Moore Felix AH Sperling Dezene P W Huber Inanc Birol Steven JM Jones Joerg Bohlmann 《Genome biology》2013,14(3):R27
6.
A. Daneshjoo AH. Mokhtar N. Rahnama A. Yusof 《Biology of sport / Institute of Sport》2013,30(4):281-288
The study investigates the effects of the 11+ and HarmoKnee injury prevention programmes on knee strength in male soccer players. Under-21-year-old players (n=36) were divided equally into: the 11+, HarmoKnee and control groups. The programmes were performed for 24 sessions (20-25 min each). The hamstrings and quadriceps strength were measured bilaterally at 60°·s-1, 180°·s-1 and 300°·s-1. The concentric quadriceps peak torque (PT) of the 11+ increased by 27.7% at 300°·s-1 in the dominant leg (p<0.05). The concentric quadriceps PT of HarmoKnee increased by 36.6%, 36.2% and 28% in the dominant leg, and by 31.3%, 31.7% and 20.05% at 60°·s-1, 180°·s-1 and 300°·s-1 in the non-dominant leg respectively. In the 11+ group the concentric hamstring PT increased by 22%, 21.4% and 22.1% at 60°·s-1, 180°·s-1 and 300°·s-1, respectively in the dominant leg, and by 22.3%, and 15.7% at 60°·s-1 and 180°·s-1, in the non-dominant leg. In the HarmoKnee group the hamstrings in the dominant leg showed an increase in PT by 32.5%, 31.3% and 14.3% at 60°·s-1, 180°·s-1 and 300°·s-1, and in the non-dominant leg hamstrings PT increased by 21.1% and 19.3% at 60°·s-1 and 180°·s-1 respectively. The concentric hamstrings strength was significantly different between the 11+ and control groups in the dominant (p=0.01) and non-dominant legs (p=0.02). The HarmoKnee programme enhanced the concentric strength of quadriceps. The 11+ and HarmoKnee programmes are useful warm-up protocols for improving concentric hamstring strength in young professional male soccer players. The 11+ programme is more advantageous for its greater concentric hamstring strength improvement compared to the HarmoKnee programme. 相似文献
7.
Purification and properties of pyrophosphatase of Acinetobacter johnsonii 210A and its involvement in the degradation of polyphosphate 总被引:1,自引:0,他引:1
Inorganic pyrophosphatase (E.C. 3.6.1.1) of Acinetobacter johnsonii210A was purified 200-fold to apparent homogeneity. The enzyme catalyzedthe hydrolysis of inorganic pyrophosphate and triphosphate to orthophosphate.No activity was observed with other polyphosphates and a wide variety oforganic phosphate esters. The molecular mass of the enzyme was estimatedto be 141 kDa by gelfiltration. Sodium dodecyl sulfate-polyacrylamide gelelectrophoresis indicated a subunit composition of six identical polypeptideswith a molecular mass of 23 kDa. The cation Mg2 was required foractivity, the activity with Mn2, Co2 and Zn2 was 48, 48 and 182% of the activity observed with Mg2, respectively. The enzyme was heat-stable and inhibited by fluoride and iodoacetamide. The analysis of the kinetic properties of the enzyme revealed an apparent Km for pyrophosphate of 0.26 mM. In A. johnsonii 210A, pyrophosphatase may be involved in the degradation of high-molecular polyphosphates under anaerobic conditions: (i) it catalyses the further hydrolysis of pyrophosphate and triphosphate formed from high-molecular weight polyphosphates by the action of exopolyphosphatase, and (ii) it abolishes the inhibition of polyphosphate: AMP phosphotransferase-mediated degradation by pyrophosphate and triphosphate. 相似文献
8.
We assessed the utility of fluorescent in situ hybridization (FISH) in the screening of clone libraries of (meta)genomic or environmental DNA for the presence and expression of bacterial ribosomal RNA (rRNA) genes. To establish proof-of-principle, we constructed a fosmid-based library in Escherichia coli of large-sized genomic DNA fragments of the mycophagous soil bacterium Collimonas fungivorans, and hybridized 768 library clones with the Collimonas-specific fluorescent probe CTE998-1015. Critical to the success of this approach (which we refer to as large-insert library FISH or LIL-FISH) was the ability to induce fosmid copy number, the exponential growth status of library clones in the FISH assay and the use of a simple pooling strategy to reduce the number of hybridizations. Twelve out of 768 E. coli clones were suspected to harbour and express Collimonas 16S rRNA genes based on their hybridization to CTE998-1015. This was confirmed by the finding that all 12 clones were also identified in an independent polymerase chain reaction-based screening of the same 768 clones using a primer set for the specific detection of Collimonas 16S ribosomal DNA (rDNA). Fosmids isolated from these clones were grouped by restriction analysis into two distinct contigs, confirming that C. fungivorans harbours at least two 16S rRNA genes. For one contig, representing 1-2% of the genome, the nucleotide sequence was determined, providing us with a narrow but informative view of Collimonas genome structure and content. 相似文献
9.
Dmytro V. Gospodaryov Oleh V. Lushchak Bohdana M. Rovenko Natalia V. Perkhulyn Mike Gerards Tea Tuomela Howard T. Jacobs 《BBA》2014
An assembled cDNA coding for the putative single-subunit NADH dehydrogenase (NDX) of Ciona intestinalis was introduced into Drosophila melanogaster. The encoded protein was found to localize to mitochondria and to confer rotenone-insensitive substrate oxidation in organello. Transgenic flies exhibited increased resistance to menadione, starvation and temperature stress, and manifested a sex and diet-dependent increase in mean lifespan of 20–50%. However, NDX was able only weakly to complement the phenotypes produced by the knockdown of complex I subunits. 相似文献
10.
Melek Güler-Yüksel Naomi B Klarenbeek Yvonne PM Goekoop-Ruiterman Jeska K de Vries-Bouwstra Sjoerd M van der Kooij Andreas H Gerards H Karel Ronday Tom WJ Huizinga Ben AC Dijkmans Cornelia F Allaart Willem F Lems 《Arthritis research & therapy》2010,12(3):R96