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排序方式: 共有225条查询结果,搜索用时 31 毫秒
91.
Frank Förste Ioanna Mantouvalou Birgit Kanngießer Hagen Stosnach Lena Anna-Maria Lachner Karsten Fischer Kirsten Krause 《Physiologia plantarum》2020,168(4):934-947
The uptake of inorganic nutrients by rootless parasitic plants, which depend on host connections for all nutrient supplies, is largely uncharted. Using X-ray fluorescence spectroscopy (XRF), we analyzed the element composition of macro- and micronutrients at infection sites of the parasitic angiosperm Cuscuta reflexa growing on hosts of the genus Pelargonium. Imaging methods combining XRF with 2-D or 3-D (confocal) microscopy show that most of the measured elements are present at similar concentrations in the parasite compared to the host. However, calcium and strontium levels drop pronouncedly at the host/parasite interface, and manganese appears to accumulate in the host tissue surrounding the interface. Chlorine is present in the haustorium at similar levels as in the host tissue but is decreased in the stem of the parasite. Thus, our observations indicate a restricted uptake of calcium, strontium, manganese and chlorine by the parasite. Xylem-mobile dyes, which can probe for xylem connectivity between host and parasite, provided evidence for an interspecies xylem flow, which in theory would be expected to carry all of the elements indiscriminately. We thus conclude that inorganic nutrient uptake by the parasite Cuscuta is regulated by specific selective barriers whose existence has evaded detection until now. 相似文献
92.
Luigi Ferrucci John R.B. Perry Amy Matteini Markus Perola Toshiko Tanaka Kaisa Silander Neil Rice David Melzer Anna Murray Christie Cluett Linda P. Fried Demetrius Albanes Anna-Maria Corsi Antonio Cherubini Jack Guralnik Stefania Bandinelli Andrew Singleton Jarmo Virtamo Jeremy Walston Richard D. Semba Timothy M. Frayling 《American journal of human genetics》2009,84(2):123-133
Low plasma levels of carotenoids and tocopherols are associated with increased risk of chronic disease and disability. Because dietary intake of these lipid-soluble antioxidant vitamins is only poorly correlated with plasma levels, we hypothesized that circulating carotenoids (vitamin A-related compounds) and tocopherols (vitamin E-related compounds) are affected by common genetic variation. By conducting a genome-wide association study in a sample of Italians (n = 1190), we identified novel common variants associated with circulating carotenoid levels and known lipid variants associated with α-tocopherol levels. Effects were replicated in the Women's Health and Aging Study (n = 615) and in the α-Tocopherol, β-Carotene Cancer Prevention (ATBC) study (n = 2136). In meta-analyses including all three studies, the G allele at rs6564851, near the β-carotene 15,15′-monooxygenase 1 (BCMO1) gene, was associated with higher β-carotene (p = 1.6 × 10−24) and α-carotene (p = 0.0001) levels and lower lycopene (0.003), zeaxanthin (p = 1.3 × 10−5), and lutein (p = 7.3 × 10−15) levels, with effect sizes ranging from 0.10–0.28 SDs per allele. Interestingly, this genetic variant had no significant effect on plasma retinol (p > 0.05). The SNP rs12272004, in linkage disequilibrium with the S19W variant in the APOA5 gene, was associated with α-tocopherol (meta-analysis p = 7.8 × 10−10) levels, and this association was substantially weaker when we adjusted for triglyceride levels (p = 0.002). Our findings might shed light on the controversial relationship between lipid-soluble anti-oxidant nutrients and human health. 相似文献
93.
94.
Summary We examined the possibility that the recA441 mutation, which partially suppresses the UV sensitivity of uvr recF mutant bacteria, exerts its effect by coding for an altered RecA protein that competes more efficiently than the RecA+ protein with SSB for ssDNA in vivo. Using an assay measuring recombination between UV-damaged DNA and intact homologous DNA, we found that the introduction of the recA441 mutation partially suppressed the defects in recombination in bacteria lacking RecF activity but not in bacteria with excess SSB, although recombination was affected more in recF mutants than in bacteria overproducing SSB. These results therefore do not support the hypothesis that RecA441 protein, or RecA protein with the help of RecF protein, is required during recombination of UV-damaged DNA to compete with SSB for ssDNA. 相似文献
95.
96.
Hjörleifsdóttir Sigrídur Pétursdóttir Sólveig K. Korpela Jaana Torsti Anna-Maria Mattila Pekka Kristjánsson Jakob K. 《Biotechnology Techniques》1996,10(1):13-18
Summary A total of 216 Icelandic aerobic, heterotrophic, thermophiles belonging to three different genera were screened for type II restriction endonucleases. The frequency of positive strains was 44% for both Thermus and Bacillus but 63% for Rhodothermus. Approximately half of the enzymes from each group were characterised and a total of 14 different restriction enzymes were found. In all cases they were isoschizomers of known enzymes. Thermus contained 9 different types, Bacillus 6 and Rhodothermus had 3. This is the first time that isoschizomers of BspEI, BglI, EagI and EcoRV are found in Thermus and BstBI and EcoRV are found in Rhodothermus. 相似文献
97.
A method for the determination of urinary aldosterone has been developed which appears to be applicable for the clinical laboratory. Ten ml of urine were used for analysis. The purification of aldosterone consisted of hydrolysis at pH 1.0; CH2Cl2 extraction and column chromatography on Sephadex LH-20. Recovery of added 4-14C-D-aldosterone was 44.7 + 7.1 (2 SD) % for 60 experiments. The extraction was followed by a rapid radioimmunoassay analysis of aldosterone. The sensitivity of the overall assay was 1.6 μg aldosterone, the accuracy 92.0 ±3.4 %. The coefficient of variation was within one assay 14 % for a given sample (n = 19) and 20 % for multiple assays. Excretion of aldosterone as determined in 17 healthy individuals on an uncontrolled diet was 9.5 ± 3.6 (SD) μg per 24 hours. Patients suffering from renal arterial stenosis or from essential hypertension presented an increase of aldosterone excretion upon sodium restriction. An increased excretion of aldosterone without any response to reduced sodium uptake was found in patients with primary aldosteronism. 相似文献
98.
Gunther Seckmeyer Merle Glandorf Cordula Wichers Richard McKenzie Diamantino Henriques Fernanda Carvalho Ann Webb Anna-Maria Siani Alkiviadis Bais Berit Kjeldstad Colette Brogniez Peter Werle Tapani Koskela Kaisa Lakkala Julian Gr?bner Harry Slaper Peter denOuter Uwe Feister 《Photochemical & photobiological sciences》2008,7(8):925-930
Irradiation in the ultraviolet wavelength range is found to be up to 50% lower in the European summer compared to sites with comparable latitudes in New Zealand. We have developed a method to quantitatively attribute the causes for such differences between sites by analysis of spectra. We conclude that these large differences are caused mainly by differences in total ozone, cloudiness, aerosol loading and Sun-Earth separation. The relative contribution of clouds varies from year to year and it is site dependent. Averaged over several years we find a strong latitudinal gradient of the cloud impact within Europe, with much less cloud attenuation in southern Europe. Due to the differences in total ozone and aerosol loading, the UV-B levels are generally lower in Europe compared to New Zealand. It is likely that inter-hemispheric differences will change in coming decades due to a combination of changes in ozone concentrations, air pollution and cloudiness as a result of climate change. However, since the future evolution of these major parameters is highly uncertain, the magnitude and even the sign of such changes are not known yet. 相似文献
99.
Howard S. Fox Gail R. Martin Mary F. Lyon Bernhard Herrmann Anna-Maria Frischauf Hans Lehrach Lee M. Silver 《Cell》1985,40(1):63-69
Four genomic clones obtained from microdissected fragments of the proximal portion of mouse chromosome 17 have been used to identify a series of t-haplotype-specific restriction fragments. Their specificity is defined by presence in eight complete t haplotypes and absence from 18 inbred strains of wild-type mice. Partial t haplotypes contain subsets of the t-specific fragments, and each can be classified according to the t-specific fragments it contains. This is the first molecular evidence that independent partial t haplotypes contain different lengths of t haplotype DNA. Recombination studies indicate that partial t haplotypes suppress recombination in proportion to the extent of t haplotype DNA they contain. Molecular analysis of partial t haplotyes shows that the t-specific fragments map to and thus define different regions of the t complex. Certain regions of t haplotype DNA defined by t-specific restriction fragments can be correlated with loci involved in the control of transmission ratio distortion. 相似文献
100.
A new DNA marker (D4S90) is located terminally on the short arm of chromosome 4, close to the Huntington disease gene 总被引:4,自引:0,他引:4
S Youngman M Sarfarazi M Bucan M MacDonald B Smith M Zimmer C Gilliam A M Frischauf J J Wasmuth J F Gusella 《Genomics》1989,5(4):802-809
Genetic linkage studies have mapped Huntington's disease (HD) to the distal portion of the short arm of chromosome 4 (4p16.3), 4 cM distal to D4S10 (G8). To date, no definite flanking marker has been identified. A new DNA marker, D4S90 (D5); which maps to the distal region of 4p16.3, is described. The marker was used in a genetic linkage study in the CEPH reference families with seven other markers at 4p16. The study, together with knowledge of the physical map of the region, places D4S90 as the most distal marker, 6 cM from D4S10. A provisional linkage study with HD gave a maximum lod score of 2.14 at a theta of 0.00 and no evidence of linkage disequilibrium. As D4S90 appears to be located terminally, it should play an important role in the accurate mapping and cloning of the HD gene. 相似文献