全文获取类型
收费全文 | 2935篇 |
免费 | 197篇 |
出版年
2024年 | 6篇 |
2023年 | 21篇 |
2022年 | 44篇 |
2021年 | 85篇 |
2020年 | 57篇 |
2019年 | 60篇 |
2018年 | 78篇 |
2017年 | 82篇 |
2016年 | 114篇 |
2015年 | 172篇 |
2014年 | 206篇 |
2013年 | 226篇 |
2012年 | 256篇 |
2011年 | 252篇 |
2010年 | 152篇 |
2009年 | 160篇 |
2008年 | 183篇 |
2007年 | 166篇 |
2006年 | 143篇 |
2005年 | 118篇 |
2004年 | 108篇 |
2003年 | 108篇 |
2002年 | 119篇 |
2001年 | 31篇 |
2000年 | 13篇 |
1999年 | 20篇 |
1998年 | 23篇 |
1997年 | 15篇 |
1996年 | 16篇 |
1995年 | 12篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1985年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1961年 | 3篇 |
排序方式: 共有3132条查询结果,搜索用时 15 毫秒
991.
Cadmium (Cd) is a heavy metal of considerable occupational and environmental concern affecting wildlife and human health. Recent studies indicate that Cd, like other heavy metals, can mimic effects of 17β-estradiol (E2) involving E2 receptor (ER) activation. Lactotrophs, the most abundant cell type in anterior pituitary gland, are the main target of E2, which stimulates cell proliferation and increases prolactin secretion through ERα. The aim of this work was to examine whether Cd at nanomolar concentrations can induce cell proliferation and prolactin release in anterior pituitary cells in culture and whether these effects are mediated through ERs. Here we show that 10 nM Cd was able to stimulate lactotroph proliferation in anterior pituitary cell cultures from female Wistar rats and also in GH3 lactosomatotroph cell line. Proliferation of somatotrophs and gonadotrophs were not affected by Cd exposure. Cd promoted cell cycle progression by increasing cyclins D1, D3 and c-fos expression. Cd enhanced prolactin synthesis and secretion. Cd E2-like effects were blocked by the pure ERs antagonist ICI 182,780 supporting that Cd acts through ERs. Further, both Cd and E2 augmented full-length ERαexpression and its 46 kDa-splicing variant. In addition, when co-incubated Cd was shown to interact with E2 by inducing ERα mRNA expression which indicates an additive effect between them. This study shows for the first time that Cd at nanomolar concentration displays xenoestrogenic activities by inducing cell growth and stimulating prolactin secretion from anterior pituitary cells in an ERs-dependent manner. Cd acting as a potent xenoestrogen can play a key role in the aetiology of different pathologies of the anterior pituitary and in estrogen-responsive tissues which represent considerable risk to human health. 相似文献
992.
993.
994.
Beatriz Gonçalves Odrade Nougué Florian Jabbour Céline Ridel Halima Morin Patrick Laufs Domenica Manicacci Catherine Damerval 《The Plant journal : for cell and molecular biology》2013,76(2):223-235
Flower architecture mutants provide a unique opportunity to address the genetic origin of flower diversity. Here we study a naturally occurring floral dimorphism in Nigella damascena (Ranunculaceae), involving replacement of the petals by numerous sepal‐like and chimeric sepal/stamen organs. We performed a comparative study of floral morphology and floral development, and characterized the expression of APETALA3 and PISTILLATA homologs in both morphs. Segregation analyses and gene silencing were used to determine the involvement of an APETALA3 paralog (NdAP3–3) in the floral dimorphism. We demonstrate that the complex floral dimorphism is controlled by a single locus, which perfectly co‐segregates with the NdAP3–3 gene. This gene is not expressed in the apetalous morph and exhibits a particular expression dynamic during early floral development in the petalous morph. NdAP3–3 silencing in petalous plants perfectly phenocopies the apetalous morph. Our results show that NdAP3–3 is fully responsible for the complex N. damascena floral dimorphism, suggesting that it plays a role not only in petal identity but also in meristem patterning, possibly through regulation of perianth organ number and the perianth/stamen boundary. 相似文献
995.
996.
Aline Crespo Bouzon Bárbara Cristina Da Silva Meireles Igo Vieira Souza Fabiano Venancio Dias Beatriz Goldschmidt 《Journal of medical primatology》2020,49(1):52-55
Hypomelanosis of Ito is a rare neurocutaneous syndrome, characterized by streaks and swirls of hypopigmentation arranged in a Blaschkoid pattern. Other associated anomalies are observed. We report a case of a male cynomolgus monkey (Macaca fascicularis) who presented the characteristic of hypomelanosis of Ito with palmoplantar involvement and polythelia. 相似文献
997.
Amaral Suélen Cavalheiro Pruski Beatriz Bohns de Freitas Stella Buchhorn Allend Suzane Olachea Ferreira Marcos Roberto Alves Moreira Clóvis Pereira Daniela Isabel Brayer Junior Antonio Sergio Varela Hartwig Daiane Drawanz 《Molecular biology reports》2020,47(12):9615-9625
Molecular Biology Reports - Antimicrobial resistance is increasing around the world and the search for effective treatment options, such as new antibiotics and combination therapy is urgently... 相似文献
998.
999.
In the present paper the formation of complexes between positively charge polyelectrolyte (polyethyleneimine and chitosan) and Candida rugosa lipase from a crude extract and porcine lipase from pancreas commercial homogenate preparations were analyzed. The solubility of lipases-cationic polyelectrolytes formation was dependent on: polyelectrolyte densities electrical charge, polyelectrolyte and enzyme concentrations and salts present in the solution. The lipase was recovered from the non-soluble complex by adding of NaCl at a given pH. Although the polyelectrolytes did not affect lipase biological activity, both of them produced good enzyme recovery (>90%); however, purification factors were low. This methodology appears to be a good previous prepurification and concentration method, using, low-cost polymers, allows the design of a purification method where the protein of interest is present in a large volume with respect to the small amount of polyelectrolyte added. 相似文献
1000.
Vieites M Smircich P Pagano M Otero L Fischer FL Terenzi H Prieto MJ Moreno V Garat B Gambino D 《Journal of inorganic biochemistry》2011,105(12):1704-1711
In the search for drugs with anti-trypanosome activity, we had previously synthesized two series of platinum and palladium analogous compounds of the formula [MIICl2(HL)], where HL were bioactive 5-nitrofuryl or 5-nitroacroleine thiosemicarbazone derivatives. In this work, we thoroughly characterized [MIICl2(HL)] complexes interaction with DNA by using different techniques: gel electrophoresis, DNA viscosity measurements, circular dichroism (CD) and atomic force microscopy (AFM). Electrophoresis results showed that all complexes induced a withdrawal of DNA superhelicity demonstrated by a decrease in electrophoretic mobility of supercoiled DNA form. This effect on migration was dependent on dose but also on the nature of both the metal and the ligand. In general, the effect produced by palladium complexes was significantly more intense than that observed for the corresponding platinum analogs. Differences between palladium and platinum complexes were also observed in CD experiments. While palladium complexes induce evident calf thymus (CT)-DNA profile changes compatible with B-DNA to Z-DNA conformational transition, no clear effect was observed for platinum ones. Additionally, AFM studies showed that changes in the shape of plasmid DNA, like supercoiling, kinks and thickness increase resulted more intense for the former. In addition, either Pd or Pt complexes increased the viscosity of CT DNA solutions in a concentration dependent manner. Although the nature of DNA interaction of both series of analogous palladium and platinum complexes seemed to be similar, an explanation for the observed differential intensity of the effect could be related to the known kinetic stability differences between palladium and platinum compounds. 相似文献