全文获取类型
收费全文 | 360篇 |
免费 | 21篇 |
专业分类
381篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 10篇 |
2018年 | 16篇 |
2017年 | 16篇 |
2016年 | 21篇 |
2015年 | 21篇 |
2014年 | 21篇 |
2013年 | 31篇 |
2012年 | 29篇 |
2011年 | 27篇 |
2010年 | 16篇 |
2009年 | 16篇 |
2008年 | 24篇 |
2007年 | 29篇 |
2006年 | 17篇 |
2005年 | 20篇 |
2004年 | 16篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 4篇 |
1988年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有381条查询结果,搜索用时 15 毫秒
51.
52.
Edyta Skrzypek Ilona Czyczyło-Mysza Izabela Marcińska Maria Wędzony 《Plant Cell, Tissue and Organ Culture》2008,94(2):131-137
Anthers cultures of six Polish cultivars of pasture lupin (Lupinus L.) were examined for their androgenic response. Anthers with microspores at the uninucleate stage were isolated from flower
buds and cultured in liquid media. Better viability of androgenetic structures was obtained when donor plants had grown under
field as opposed to greenhouse conditions. A density of five anthers per 0.5 ml medium was more conducive to androgenetic
induction than 25 anthers per 0.5 ml medium. Addition of 5% maltose to the induction medium and culture at 25°C without pre-treatment
of flowers, buds or anthers promoted microspore release and division. The greatest frequency of androgenic callus, ~70% was
developed from cvs. Katon, Wat (white lupin), in contrast to cvs. Legat, Juno (yellow lupin), Polonez and Sonet (narrow-leafed
lupin) with callus induction ~30–40%. Despite various combinations of media tested, plant regeneration was not obtained from
anther derived callus. 相似文献
53.
54.
Monika Lesicka Ewa Jabłońska Edyta Wieczorek Barbara Seroczyńska Leszek Kalinowski Jarosław Skokowski 《Chronobiology international》2013,30(8):1103-1114
ABSTRACTOne of the supposed mechanisms that may lead to breast cancer (BC) is an alteration of circadian gene expression and DNA methylation. We undertook an integrated approach to identify methylation pattern of core circadian promoter regions in BC patients with regard to clinical features. We performed a quantitative methylation-specific real-time PCR analysis of a promoter methylation profile in 107 breast tumor and matched non-tumor tissues. A panel of circadian genes CLOCK, BMAL1, PERIOD (PER1, 2, 3), CRYPTOCHROME (CRY1, 2) and TIMELESS as well as their association with clinicopathological characteristics were included in the analysis. Three out of the eight analyzed genes exhibited marked hypermethylation (PER1, 2, 3), whereas CLOCK, BMAL1, CRY2 showed significantly lower promoter CpG methylation in the BC tissues when compared to the non-tumor tissues. Among variously methylated genes we found an association between the elevated methylation level of PERs promoter region and molecular subtypes, histological subtypes and tumor grading of BC. Methylation status may be associated with a gene expression level of circadian genes in BC patients. An aberrant methylation pattern in circadian genes in BC may provide information that could be used as novel biomarkers in clinics and molecular epidemiology as well as play an important role in BC etiology. 相似文献
55.
Angelika Noga Edyta Skrzypek Marzena Warchoł Ilona Czyczyło-Mysza Kinga Dziurka Izabela Marcińska Katarzyna Juzoń Tomasz Warzecha Agnieszka Sutkowska Zygmunt Nita Krystyna Werwińska 《In vitro cellular & developmental biology. Plant》2016,52(6):590-597
Obtaining oat DH lines is only effective via wide crossing with maize. Seven hundred haploid embryos from 21 single F1 progeny obtained from wide crosses with maize were isolated, divided into four groups according to their size (<0.5 mm, 0.5–0.9 mm, 1.0–1.4 mm, and ≥1.5 mm), and transferred into 190–2 regeneration medium with different growth regulators: 0.5 mg L?1 kinetin (KIN) and 0.5 mg L?1 1-naphthaleneacetic acid (NAA); 1 mg L?1 zeatin (ZEA) and 0.5 mg L?1 NAA; or 1 mg L?1 dicamba (DIC), 1 mg L?1 picloram (PIC), and 0.5 mg L?1 kinetin (KIN). Among all isolated embryos, approximately 46.1% were between 1.0–1.4 mm, while the smallest group of embryos (7.1%) were those <0.5 mm. The ability of haploid embryos to germinate varied depending on oat genotypes and the size of embryos. Haploid embryos <0.5 mm were globular and did not germinate, whereas embryos ≥1.5 mm had clearly visible coleoptiles, radicles, and scutella, and were able to germinate. Germination of oat haploid embryos varied depending on growth regulators in the regeneration medium. Most haploid embryos germinated on medium with 0.5 mg L?1 NAA and 0.5 mg L?1 KIN, while the fewest germinated on medium with 1 mg L?1 DIC, 1 mg L?1 PIC, and 0.5 mg L?1 KIN. One hundred thirty germinated haploid embryos converted into haploid plants. Fifty oat DH lines were obtained after colchicine treatment. 相似文献
56.
Edyta?WrobelEmail author Joanna?Leszczynska Edyta?Brzoska 《Cellular & molecular biology letters》2016,21(1):26
Background
The primary human bone-derived cell culture technique is used as a model to study human osteogenesis. Compared to cell line cultures, primary osteoprogenitor and osteoblast cultures provide more complex information about osteogenesis, bone remodeling and regeneration than cell line cultures.Methods
In this study, we isolated human bone-derived cells (HBDCs) and promoted their differentiation into osteoblasts. The following parameters were evaluated: cell number and viability, total protein expression, alkaline phosphatase activity, collagenous matrix production and osteogenic genes expression, i.e., gene coding for type I collagen and alkaline phosphatase.Results
It was proved the results show that HBDCs intensively proliferate during the first 7 days of culture followed by differentiation accompanied by an increase in alkaline phosphatase activity. Moreover, it was observed that during the differentiation of HBDCs, the expression of integrin β1 increased.Conclusions
The process was also accompanied by changes in cell shape and rearrangement of the actin cytoskeleton and focal contacts containing FAK and the integrin β1 subunit. We suggest that the β1 integrin subunit may be a suitable new target in studies of the differentiation of primary human osteoblasts in culture.57.
58.
Reduced fertility of female mice lacking CD81 总被引:7,自引:0,他引:7
Rubinstein E Ziyyat A Prenant M Wrobel E Wolf JP Levy S Le Naour F Boucheix C 《Developmental biology》2006,290(2):351-358
In somatic cells, the tetraspanins CD81 and CD9 associate with each other, with additional tetraspanins and with non-tetraspanin molecules to form proteolipidic complexes. Here we show that CD81 is expressed on the surface of oocytes where it associates with tetraspanin-enriched membrane structures. A major CD9 and CD81 partner, CD9P-1, is also expressed by oocytes. Deletion of CD81 gene in mice results in a 40% reduction of female fertility. In vitro insemination indicated that this infertility is due to a deficiency of oocytes to fuse with sperm. While the fertility of CD9-/- mice is severely but not completely impaired, double knock-out CD9-/- CD81-/- mice were completely infertile indicating that CD9 and CD81 play complementary roles in sperm-egg fusion. Finally, a fraction of CD9 was transferred from CD81-/- oocytes to sperm present in the perivitelline space indicating that the defect of fusion of CD81-/- oocytes does not result from an impaired initial gamete interaction. 相似文献
59.
60.