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1.
R. J. Benzie 《CMAJ》1979,120(6):685-692
The current status of antenatal genetic diagnosis is reviewed and the limitations of present techniques are discussed. It is suggested that multidisciplinary clinics are the most efficient means of providing this aspect of health care. Advances in cell culture techniques, in ultrasonography and in fetoscopy will extend the services available, and the impact of this will be felt by the community. Education of the medical profession and the public in this area is necessary so that informed decision-making can take place. 相似文献
2.
John A. H. Benzie 《Hydrobiologia》1987,145(1):51-65
The AustralianDaphnia (D. occidentalis, D. jollyi, D. lumholtzi, D. carinata, D. nivalis, andD. cephalata) include representatives from three distinct groups within the genus. The worldwide distribution of species within these three
groups is consistent with a Gondwanan or pre-Gondwanan origin for each group. These data suggest an even more ancient origin
for the genusDaphnia.
The finding thatD. cephalata must have been separated fromD. carinata since Gondwanan times is consistent with recent biochemical data on the phylogenetic relations of AustralianDaphnia, but contrasts with electrophoretic evidence of continuing hybridization between these two taxa. It is suggested that continued
gene exchange between otherwise discrete species, or clonal complexes, ofDaphnia may be maintained for millions of years, partly as a result of the varying degrees of cyclical parthenogenesis, and partly
as a result of the highly fragmented population structures, found in these taxa. 相似文献
3.
4.
An Ustilago maydis ergosterol biosynthesis mutant (A14) which is partially blocked in sterol 14alpha-demethylase (P45014DM) activity is described. This mutant accumulated the abnormal 14alpha-methyl sterols, eburicol, 14alpha-methylfecosterol, and obtusifoliol, along with significant amounts of ergosterol. Although the A14 mutant grew nearly as well as the wild type, it was impaired in cell extension growth, which indicated a dysfunction in apical cell wall synthesis. The mutant was also found to be hypersensitive to the azole fungicides penconazole and tebuconazole. 相似文献
5.
Indo-West Pacific patterns of genetic differentiation in the high-dispersal starfish Linckia laevigata 总被引:1,自引:0,他引:1
Genetic variation in four natural populations of the starfish Linckia laevigata from the Indo-West Pacific was examined using restriction fragment analysis of a portion of the mtDNA including the control region. Digestion with seven restriction enzymes identified 47 haplotypes in a sample of 326 individuals. Samples collected from reef sites within each location were not significantly differentiated based on ΦST or spatial distribution of haplotypes, indicating that dispersal is high over short to moderate distances. Evidence of gene flow is further supported by the low divergence among haplotypes and the lack of any clear geographical structuring among different haplotypes in the gene phylogeny. However, analysis of molecular variance ( AMOVA ), ΦST and contingency χ2 analyses of the spatial distribution of haplotypes demonstrate the presence of significant broad scale population genetic structure among the four widespread locations examined. RFLP data are consistent with high gene flow between the Philippines and Western Australia and moderate gene flow between the Great Barrier Reef (GBR) and Fiji, but only limited gene flow between either the Philippines or Western Australia and either the GBR or Fiji. The presence of mtDNA structure contrasts with previous allozyme data which suggest that dispersal among widely separated locations is equivalent to dispersal among populations within the highly connected GBR studies. This discordance between patterns of gene flow inferred from these two markers cannot be fully accounted for by differences in effective population size for mtDNA. This might suggest that while mtDNA variation may represent contemporary patterns of gene flow, allozyme variation among populations is yet to reach equilibrium between drift and migration over the range surveyed. 相似文献
6.
7.
Initiation reactions in the mRNA-dependent reticulocyte lysate 总被引:1,自引:0,他引:1
Reticulocyte lysates depleted of mRNA by digestion with micrococcal nuclease still show an unexpectedly high rate of formation of 80 S initiation complexes. Formation of these complexes is sensitive to all inhibitors of the normal protein synthesis initiation process tested. Such lysates contain high concentrations of mRNA fragments which can be utilized for initiation, with which exogenous mRNA must compete. As a consequence of this competition, mRNAs that are weak initiators may be translated poorly by this system even at low exogenous mRNA concentrations. 相似文献
8.
9.
JA Kiernan 《Biotechnic & histochemistry》2013,88(5-6):203-210
Hexazonium pararosaniline is a valuable reagent that has been used in enzyme activity histochemistry for 50 years. It is an aqueous solution containing the tris-diazonium ion derived from pararosaniline, an aminotriarylmethane dye, and it contains an excess of nitrous acid that was not consumed in the diazotization reaction. Other investigators have found that immersion for 2 min in an acidic (pH 3.5) 0.0015 M hexazonium pararosaniline solution can protect cryostat sections of unfixed animal tissues from the deleterious effects of aqueous reagents such as buffered solutions used in immunohistochemistry, while preserving specific affinities for antibodies. In the present investigation hexazonium pararosaniline protected lymphoid tissue and striated muscle against the damaging effects of water or saline. The same protection was conferred on unfixed sections treated with dilute nitrous or hydrochloric acid in concentrations similar to those in hexazonium pararosaniline solutions. Model tissues (solutions, gels or films containing gelatin and/or bovine albumin) responded predictably to well known cross-linking (formaldehyde) or coagulant (mercuric chloride) fixatives. Hexazonium pararosaniline solutions prevented the dissolution of protein gels in water only after 9 or more days of contact, during which time considerable swelling occurred. It is concluded that there is no evidence for a “fixative” action of hexazonium pararosaniline. The protective effect on frozen sections of unfixed tissue is attributable probably to the low pH of the solution. 相似文献
10.
I. F. F. Benzie J. J. Strain 《Redox report : communications in free radical research》2013,18(4):233-238
SummaryBiochemical tests of antioxidant status may be useful in measuring oxidative stress, however the time, skills and resources required for most such tests have limited their application and evaluation. In this study, newly available tests for two indices of antioxidant status, ferric reducing ability of plasma (FRAP) and ascorbic acid, were combined in one simple, rapid, automated test, referred to as FRASC.Results are available within 5 min of sample/reagent mixing. Linear dose-response is seen over a wide concentration range for both parameters. In- and between- run CVs were <1.0% and <3.0% respectively at 900–1800 μmol/l FRAP, and <5.0% for both at 20–400 μmol/l ascorbic acid. Mean (SD) FRAP values and ascorbic acid concentrations of fasting plasma from 130 healthy adults were 1018 (198) and 51 (18) μmol/l respectively.This combined test is straightforward and inexpensive, and lends itself to the measurement of ‘antioxidant’ (reducing) capacity and ascorbic acid concentrations of various biological fluids, as well as extracts of drugs and foodstuffs. FRASC will, therefore, facilitate experimental and clinical studies of pro-oxidant: antioxidant balance and oxidative stress-related disease. 相似文献