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71.
Background
Identifying structurally similar proteins with different chain topologies can aid studies in homology modeling, protein folding, protein design, and protein evolution. These include circular permuted protein structures, and the more general cases of non-cyclic permutations between similar structures, which are related by non-topological rearrangement beyond circular permutation. We present a method based on an approximation algorithm that finds sequence-order independent structural alignments that are close to optimal. We formulate the structural alignment problem as a special case of the maximum-weight independent set problem, and solve this computationally intensive problem approximately by iteratively solving relaxations of a corresponding integer programming problem. The resulting structural alignment is sequence order independent. Our method is also insensitive to insertions, deletions, and gaps. 相似文献72.
白踝按蚊种团是由很多形态近似的蚊种组成,其中巴拉巴按蚊和白踝按蚊均为东南亚一带的重要传疟媒介。我国过去资料均记载为白踝按蚊,但未从形态上详细鉴定。为了确定该种的分类地位,1963年作者等在海南岛万宁县兴隆附近山林区采集“白踝按蚊”全套标本10批共150多套,1971年后从云南省采集少数标本进行形态鉴定,发现其与Colless(1956,1957)所描述的白踝按蚊Anopheles leucosphyrus leucosphyrus Donitz(1901)有很明显的差别,而与巴拉巴按蚊A.balabacensis balabacensis Balsas(1936)除某些特征略有差异外,余均完全一致。按Colless的分类法,过去我国记载的“白踝按蚊”,应鉴定为巴拉巴按蚊A.balabacensis balabacensis Baisas。 相似文献
73.
为了探讨Ghrelin是否在昆明系小白鼠(Mus musculus)体内早期胚胎发育中发挥作用。运用激素超排卵技术及动物解剖学方法获取小鼠体内不同发育阶段的早期胚胎,应用实时定量PCR技术检测了Ghrelin mRNA的相对表达量。结果表明,Ghrelin mRNA在小鼠各期胚胎中均有表达;同时,GhrelinmRNA的表达量呈现一定规律性变化,2-细胞期表达量最低,8-细胞期表达量达到最高值,总体趋势是先降低后升高之后又降低。研究结果揭示,Ghrelin可能在小鼠早期胚胎发育中发挥一定的作用。 相似文献
74.
Recovery of cassava (Manihot esculenta Crantz) plants from culture of immature zygotic embryos 总被引:1,自引:0,他引:1
An embryo culture protocol using immature cassava seeds has been developed to enhance successful seed germination and reduce
time for population establishment. Embryonic axes were excised from seeds 40 days after pollination and placed on 1/3 MS medium
supplemented with growth factors. Fruits were either air-dried at 20 °C to aid dehiscence, or dissected immediately after
harvest. Culture of embryonic axes from seeds obtained from mature fruits (90 days after pollination) served as control. Average
percent germination and plantlet recovery rate were higher for embryos cultured from non air-dried immature seeds than from
air-dried immature seeds. Immature seeds that were air-dried before germination had ≥50% reduction in germination rate and
≥75% reduction in plantlet recovery rate, indicating that cassava immature zygotic embryos are susceptible to osmotic pressure
changes. Genotypic effects were observed in shoot elongation, formation of internodes, and vigor of cultures from both mature
and immature seeds. The high percentage of plants recovered from immature seeds through embryo culture opens up opportunities
for genetic stock development in cassava that has been previously unexplored.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
75.
Provitamin A biofortification of cassava enhances shelf life but reduces dry matter content of storage roots due to altered carbon partitioning into starch
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Getu Beyene Felix R. Solomon Raj D. Chauhan Eliana Gaitán‐Solis Narayanan Narayanan Jackson Gehan Dimuth Siritunga Robyn L. Stevens John Jifon Joyce Van Eck Edward Linsler Malia Gehan Muhammad Ilyas Martin Fregene Richard T. Sayre Paul Anderson Nigel J. Taylor Edgar B. Cahoon 《Plant biotechnology journal》2018,16(6):1186-1200
76.
77.
78.
Genetic mapping of resistance to bacterial blight disease in cassava (Manihot esculenta Crantz) 总被引:1,自引:1,他引:0
V. Jorge M. A. Fregene M. C. Duque M. W. Bonierbale J. Tohme V. Verdier 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(5-6):865-872
Cassava bacterial blight (CBB), caused by Xanthomonas axonopodis pv. manihotis (Xam), is a major disease of cassava (Manihot esculenta Crantz) in Africa and South America. Planting resistant varieties is the preferred method of disease control. Recent genetic
mapping of an F1 cross (TMS 30572 × CM 2177–2) led to the construction of the first molecular genetic map of cassava. To better understand
the genetics of resistance to CBB, we evaluated individuals of the F1 cross for CBB resistance by controlled greenhouse inoculations and visually assessed symptoms on days 7, 15, and 30 days
after inoculation, using a scale where 0 = no disease and 5 = maximum susceptibility. Five Xam strains were used: CIO-84, CIO-1, CIO-136, CIO-295, and ORST X-27. Area under the disease progress curve (AUDPC) was used
as a quantitative measure of resistance in QTL analysis by single-marker regression. Based on the AUDPC values, eight QTLs
(quantitative trait loci), located on linkage groups B, D, L, N, and X of the female-derived framework map, were found to
explain 9–20% of the phenotypic variance of the crop’s response to the five Xam strains. With the male-derived framework map, four QTLs on linkage groups G and C explained 10.7–27.1% of the variance. A
scheme to confirm the usefulness of these markers in evaluating segregating populations for resistance to CBB is proposed.
Received: 20 September 1999 / Accepted: 30 December 1999 相似文献
79.
Effects of environmental conditions on the fixation and transfer of nitrogen from alfalfa to associated timothy 总被引:3,自引:0,他引:3
Nitrogen fixation (NF) by alfalfa and nitrogen transfer (NT) from alfalfa to associated timothy was studied under different
environmental conditions in controlled growth chambers, using the15N dilution technique. Evidence was obtained of NT from alfalfa to the associated timothy. Conditions that favored NF by alfalfa
resulted in an increase in its NT. Of 3 different temperature regimes (25/20, 16/14, and 12/9°C day/night), 16–25/14–20°C
was the best range for NF by alfalfa and resulted in the greatest NT. High light intensity (550 uE.m−2.sec−1) and long days (16–20 h) also caused increased NF by alfalfa and benefitting timothy more than in a regime of low light intensity
(by shading 50% or 75%) or short days (12/12 or 16/8 h day/night). When the inoculated (Rhizobium meliloti) root systems of plants were kept free from other microorganisms (axenic condition) to minimize possible decomposition of
dead tissues, lower NT from alfalfa was observed, especially at later cuts, compared to non-axenic plants. This suggests that
both direct excretion and decomposition of dead alfalfa tissues are sources of N benefit from alfalfa to associated timothy.
Contribution no 1065 of the Plant Research Centre. 相似文献
80.
黄地老虎核型多角体病毒的一些特性 总被引:1,自引:1,他引:0
黄地老虎核型多角体病毒(Agrotis segetum Nulear Polyhedrosis Virus简称AsNPV)的国内分离株(AsNPVC),多角体呈六边形,大小1.7—2.6μm,为多粒包埋类型.每个病毒束内有2—7个核衣壳,大小约52nm×308nm.感染烟青虫(Heliothis assttlta)后分离到的多角体(As-HaNPV)其形状不规则,大小0.7—2.6μm,亦为多粒包埋类型.核衣壳2—6个不等,大小约40nm×300nm.EcoR1和HindⅢ限制性内切酶电泳图谱分析表明,AsNPVCDNA和As-HaNPV DNA的EcoRI、HindIII酶切图谱一致,两者与HaNPV DNA的EcoRI,HindⅢ酶切图谱存在明显差异,AsNPVC DNA的EcoRI酶切图谱共有15个片段,分子量在12.74×106—1.18×106道尔顿之间,总分子量约88.6×106道尔顿,相当于134.25kbp.HaNPV DNA的EcoRI酶切图谱共有19个片段,分子量在13.89×106—1.10×106道尔顿之间,总分子量约93.86×106道尔顿,相当于142.25kbp.AsNPV对黄地老虎2龄和4龄幼虫以及对烟青虫4龄幼虫的LD50分别为:1.4×105pIB、7.4×104PIB和2.61×104PIB. 相似文献