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891.
892.
香雪兰外植体形态学极性决定的体细胞胚胎发生 总被引:10,自引:0,他引:10
在含有2mg/LIAA和3mg/LBAP的改良N6培养基上,香雪兰(FresiarefractaKlat)花序外植体经直接体细胞胚胎发生途径再生出新的植株。在这一形态发生过程中,一个引人注意的现象是,所有的体细胞胚都出现在花序轴切段的原形态学下端(称为胚发生端,EE),而在形态学上端(称为非胚胎发生端,NEE)无体细胞胚形成。这一形态发生的极性与地心引力的方向和外植体在培养基上的放置位置无关。在培养的早期,仅于胚发生端观察到了起始细胞的分裂。SDS聚丙烯酰胺凝胶电泳结果表明,在培养了1d的外植体的胚发生端出现了两个特殊的多肽成分,而在非胚发生端则未检测到这两种多肽。高效液相色谱分析表明,培养前外植体切段两端的内源激素(IAA)的含量无显著差别。但经过一段时间的培养,胚发生端的IAA含量明显高于非胚发生端的IAA含量,表明内源激素在体细胞胚胎发生的诱导过程中起着关键的作用。在香雪兰体细胞胚胎发生诱导的过程中,由于花序轴切段两端在分子水平和生理水平上均存在差异,使这一系统有可能成为研究体细胞胚胎发生机理的有用实验材料。 相似文献
893.
894.
Shyamala Bhaskaran Alan J. Neumann Roberta H. Smith 《In vitro cellular & developmental biology. Plant》1988,24(9):947-950
Summary Histologic examination of shoot-tip explants, 1 wk after culture initiation on Murashige and Skoog medium with 2.5 mg/liter
2,4-dichlorophenoxyacetic acid (2,4-D) and 0.05 mg/liter kinetin, reveals active meristematic centers inside cultured tissue.
Clusters of cells in these meristematic centers exhibit remarkable resemblance to the initial three divisions in the zygotic
embryo. Several such meristematic groups of cells are observed in the cultured explant at this stage. Embryogenesis is obviously
initiated very early in this tissue in the presence of 2,4-D. A well-defined, white globular embryogenic callus develops in
culture in about 4 wk, and it consists of clusters of embryoids with large cells characterized by thick cell walls, numerous
lipoidal vesicles, and localized areas of carbohydrate storage. These cells resemble the scutellar tissue of the embryo. However,
there are cells within this tissue that themselves appear embryogenic. They undergo cell division giving rise to small clusters
of cells. As long as 2,4-D is present in the medium, the cells apparently retain the capacity to proliferate and to produce
more cells capable of embryogenesis. Embryogenesis seems to occur via two processes, initiation of somatic embryos early in
culture and secondary embryogensis from the scutellar tissue that forms in vitro. 相似文献
895.
A protocol for induction of direct somatic embryogenesis, secondary embryogenesis and plant regeneration of Dendrobium cv. Chiengmai Pink was developed. Thidiazuron (TDZ) at 0.3, 1 and 3 mg dm−3 induced 5–25 % of leaf tip segments of in vitro grown plants to directly form embryos after 60 d of culture, and 1 mg dm−3 TDZ was the best treatment. Somatic embryos mostly formed from leaf surfaces near cut ends, and occasionally found on leaf
tips. Higher frequency of embryogenesis was obtained in light than in darkness. During subculture, secondary embryos developed
from outer cell layers of primary embryos. All combinations of NAA (0, 0.1, 1 mg dm−3) and TDZ (0, 0.3, 1, 3 mg dm−3) increased the multiplication rate of embryos. It takes about 8 months from embryo induction, plantlet formation to eventually
acclimatization in greenhouse. 相似文献
896.
Deena K. Kadirjan‐Kalbach Robert M. Larkin Katherine W. Osteryoung 《The Plant journal : for cell and molecular biology》2012,72(5):856-867
The Arabidopsis arc1 (accumulation and replication of chloroplasts 1) mutant has pale seedlings and smaller, more numerous chloroplasts than the wild type. Previous work has suggested that arc1 affects the timing of chloroplast division but does not function directly in the division process. We isolated ARC1 by map‐based cloning and discovered it encodes FtsHi1 (At4g23940), one of several FtsHi proteins in Arabidopsis. These poorly studied proteins resemble FtsH metalloproteases important for organelle biogenesis and protein quality control but are presumed to be proteolytically inactive. FtsHi1 bears a predicted chloroplast transit peptide and localizes to the chloroplast envelope membrane. Phenotypic studies showed that arc1 (hereafter ftsHi1‐1), which bears a missense mutation, is a weak allele of FtsHi1 that disrupts thylakoid development and reduces de‐etiolation efficiency in seedlings, suggesting that FtsHi1 is important for chloroplast biogenesis. Consistent with this finding, transgenic plants suppressed for accumulation of an FtsHi1 fusion protein were often variegated. A strong T‐DNA insertion allele, ftsHi1‐2, caused embryo‐lethality, indicating that FtsHi1 is an essential gene product. A wild‐type FtsHi1 transgene rescued both the chloroplast division and pale phenotypes of ftsHi1‐1 and the embryo‐lethal phenotype of ftsHi1‐2. FtsHi1 overexpression produced a subtle increase in chloroplast size and decrease in chloroplast number in wild‐type plants while suppression led to increased numbers of small chloroplasts, providing new evidence that FtsHi1 negatively influences chloroplast division. Taken together, our analyses reveal that FtsHi1 functions in an essential, envelope‐associated process that may couple plastid development with division. 相似文献
897.
A competent, embryogenic suspension culture of Chinese yam (Dioscorea opposita Thunb. cv. ‘Nagaimo’) has been obtained. Embryogenic callus was induced from stem segments cultured on an agar-solidified MS medium containing 2,4-dichlorophenoxyacetic acid (2,4-D). One month following placement of the embryogenic callus in a liquid medium containing 2,4-D, the embryogenic tissue began to proliferate rapidly. Established suspension cultures consisted almost entirely of early-stage pro-embryos with very little contamination from non-embryogenic tissues. Under optimum conditions, suspension culture packed cell volume increased 2.5-fold per week. Following transfer of the tissue to a hormone-free medium, the embryogenic tissue developed. Globular embryos were formed within 4 weeks and addition of benzyl adenine further enhanced development and germination. Plantlets were regenerated by culturing embryos on a hormone-free agar-solidified medium. 相似文献
898.
酿酒葡萄"梅尔诺"再生系统建立的研究 总被引:6,自引:0,他引:6
以酿酒葡萄“梅尔诺”离体胚珠、叶柄为材料.通过控制激素水平、光照和温度等,对建立再生体系的器官发生途径和体胚发生途径进行了研究。结果表明,体胚的诱导和不定芽的再生与基本培养基、叶柄的着生部位、生长调节物质种类和浓度等因素有关。由“梅尔诺”的胚珠愈伤组织再生出体细胞胚的最佳培养基配方为CPSE培养基(CP287 BA 0.2mg/L NOA 1.0mg/L),体细胞胚再生率可达47.50%。“梅尔诺”体细胞胚在CPSE培养基上100%萌发为芽状,将其切断置于培养基MS TDZ 4.0mg/L上可直接诱导出绿色不定芽,再生率为52.25%;同时在培养基MS TDZ2.0mg/L上获得了“梅尔诺”离体叶柄再生不定芽.再生率为62.42%.二者再生的不定芽的最他增殖培养基为MS BA0.5mg/L。“梅尔诺”体细胞胚的萌发芽在WPM培养基中能很好的生根及成苗,并建立了单芽茎段微繁体系。 相似文献
899.
900.
Somatic embryogenesis induced by the simple application of abscisic acid to carrot (Daucus carota L.) seedlings in culture 总被引:3,自引:0,他引:3
Seedlings of carrot (Daucus carota L. cv. Red Cored Chantenay) formed somatic embryos when cultured on medium containing abscisic acid (ABA) as the sole source
of growth regulator. The number of embryos per number of seedlings changed depending on the concentration of ABA added to
the medium, with a maximum embryo number at 1 × 10−4 M ABA. Seedling age was critical for response to exogenous ABA; no seedling with a hypocotyl longer than 3.0 cm was able to
form an embryo. Removal of shoot apices from seedlings completely inhibited the embryogenesis induced by application of exogenous
ABA, suggesting that the action of ABA requires some substance(s) that is translocated basipetally from shoot apices through
hypocotyls. Histologically, somatic embryos shared common epidermal cells and differentiated not through the formation of
embryogenic cell clumps, but directly from epidermal cells. These morphological traits are distinct from those of embryogenesis
via formation of embryogenic cell clumps, which has been found in embryogenic carrot cultures established using 2,4-dichlorophenoxyacetic
acid or other auxins. These results suggest that ABA acts as a signal substance in stress-induced carrot seedling somatic
embryogenesis.
Received: 22 April 2000 / Accepted: 8 June 2000 相似文献