全文获取类型
收费全文 | 1163篇 |
免费 | 72篇 |
出版年
2023年 | 7篇 |
2022年 | 18篇 |
2021年 | 31篇 |
2020年 | 18篇 |
2019年 | 20篇 |
2018年 | 24篇 |
2017年 | 34篇 |
2016年 | 44篇 |
2015年 | 49篇 |
2014年 | 57篇 |
2013年 | 84篇 |
2012年 | 92篇 |
2011年 | 83篇 |
2010年 | 46篇 |
2009年 | 44篇 |
2008年 | 55篇 |
2007年 | 61篇 |
2006年 | 49篇 |
2005年 | 60篇 |
2004年 | 43篇 |
2003年 | 54篇 |
2002年 | 42篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1988年 | 5篇 |
1986年 | 4篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1976年 | 4篇 |
1928年 | 3篇 |
1926年 | 4篇 |
1913年 | 8篇 |
1912年 | 5篇 |
1911年 | 3篇 |
1910年 | 3篇 |
1909年 | 4篇 |
1908年 | 6篇 |
1907年 | 4篇 |
1904年 | 7篇 |
1865年 | 5篇 |
1860年 | 3篇 |
排序方式: 共有1235条查询结果,搜索用时 31 毫秒
51.
52.
53.
Yan-Hui Wang Hao-Yang Wu Dávid Rédei Qiang Xie Yan Chen Ping-Ping Chen Zhuo-Er Dong Kai Dang Jakob Damgaard Pavel Štys Yan-Zhuo Wu Jiu-Yang Luo Xiao-Ya Sun Viktor Hartung Stefan M. Kuechler Yang Liu Hua-Xi Liu Wen-Jun Bu 《Cladistics : the international journal of the Willi Hennig Society》2019,35(1):42-66
The phylogeny of true bugs (Hemiptera: Heteroptera), one of the most diverse insect groups in terms of morphology and ecology, has been the focus of attention for decades with respect to several deep nodes between the suborders of Hemiptera and the infraorders of Heteroptera. Here, we assembled a phylogenomic data set of 53 taxa and 3102 orthologous genes to investigate the phylogeny of Hemiptera–Heteroptera, and both concatenation and coalescent methods were used. A binode-control approach for data filtering was introduced to reduce the incongruence between different genes, which can improve the performance of phylogenetic reconstruction. Both hypotheses (Coleorrhyncha + Heteroptera) and (Coleorrhyncha + Auchenorrhyncha) received support from various analyses, in which the former is more consistent with the morphological evidence. Based on a divergence time estimation performed on genes with a strong phylogenetic signal, the origin of true bugs was dated to 290–268 Ma in the Permian, the time in Earth's history with the highest concentration of atmospheric oxygen. During this time interval, at least 1007 apomorphic amino acids were retained in the common ancestor of the extant true bugs. These molecular apomorphies are located in 553 orthologous genes, which suggests the common ancestor of the extant true bugs may have experienced large-scale evolution at the genome level. 相似文献
54.
55.
Jaroslav Malina Hana Kostrhunova Vojtech Novohradsky Peter Scott Viktor Brabec 《Nucleic acids research》2022,50(2):674
The design of efficient and safe gene delivery vehicles remains a major challenge for the application of gene therapy. Of the many reported gene delivery systems, metal complexes with high affinity for nucleic acids are emerging as an attractive option. We have discovered that certain metallohelices—optically pure, self-assembling triple-stranded arrays of fully encapsulated Fe—act as nonviral DNA delivery vectors capable of mediating efficient gene transfection. They induce formation of globular DNA particles which protect the DNA from degradation by various restriction endonucleases, are of suitable size and electrostatic potential for efficient membrane transport and are successfully processed by cells. The activity is highly structure-dependent—compact and shorter metallohelix enantiomers are far less efficient than less compact and longer enantiomers. 相似文献
56.
57.
Ottenschläger I Barinova I Voronin V Dahl M Heberle-Bors E Touraev A 《Transgenic research》1999,8(4):279-294
The transient expression of three mutant forms of green fluorescent protein (GFP) genes, GFP4, GFP5ER, and GFP4S65C, under several constitutive and pollenspecific promoters throughout pollen development in Nicotianatabacum, thaliana and Antirrhinummajus is described. Immature pollen of tobacco, Arabidopsis and snapdragon, isolated at different developmental stages, were bombarded with plasmids containing the GFP and cultured in vitro for several days until maturity. The expression of GFP was monitored every day during in vitro maturation, germination and pollination, as well as after in situ pollination. The expression pattern of each construct was compared in parallel experiments to that of ßglucuronidase (GUS) constructs expressed by the same promoters. The results show that the expression level of all three GFP mutant forms was dependent on the strength of the promoter used. The strongest promoter was the DC3 promoter, and no notable differences in the intensity and brightness of all three versions of GFP were observed. GFPexpressing pollen from tobacco and snapdragon developed in vitro for several days until maturity and germinated in vitro as well as on the surface of stigmata, strongly suggesting that all three GFPs are not toxic for the development of functional pollen. Furthermore, stably transformed tobacco plants expressing GFP under the control of the strong pollenexpressed DC3 and LAT52 promoters were not impaired in reproductive function, confirming that GFP can be used as a nondestructive marker for plant reproductive biology and development. 相似文献
58.
59.
60.
Seifert M Rech M Meineke V Tilgen W Reichrath J 《The Journal of steroid biochemistry and molecular biology》2004,(1-5):375-379
1,25-DihydroxyVitamin D(3) and analogs have been shown to inhibit proliferation and to induce differentiation in different cell types, including human melanocytes. However, various tumor cell lines that fail to respond to the antiproliferative effects of Vitamin D analogs have also been reported. Using real-time PCR (LightCycler), we have compared mRNA expression of Vitamin D receptor (VDR), Vitamin D-25-hydroxylase (25-OHase), 25-hydroxyVitamin D-1alpha-hydroxylase (1alpha-OHase), and 1,25-dihydroxyVitamin D-24-hydroxylase (24-OHase) in a melanoma cell line that responds to antiproliferative effects of Vitamin D (MeWo) with a non-responsive melanoma cell line (SkMel5). Additionally, modulation of cell proliferation by calpain inhibitors, as well as regulation of mRNA expression of VDR, 1alpha-OHase, and 24-OHase genes by Vitamin D analogs were assessed in melanoma cell lines in vitro using a WST-1 based colorimetric assay and real-time PCR, respectively. RNA for VDR, 25-OHase, 1alpha-OHase, and 24-OHase was detected in melanoma cell lines. In contrast to SkMel5 cells, treatment of MeWo cells with calcitriol resulted in a dose-dependent increase in mRNA for VDR and 24-OHase as well as in a suppression of cell proliferation (up to approximately 50%). Our findings demonstrate that local synthesis or metabolism of Vitamin D metabolites may be of importance for growth regulation of MM and melanoma cell lines. Additionally, metastasizing MM represents a promising target for palliative treatment with new Vitamin D analogs that exert little calcemic side effects or for pharmacological modulation of calcitriol synthesis/metabolism in these tumors. 相似文献