全文获取类型
收费全文 | 5364篇 |
免费 | 369篇 |
出版年
2023年 | 18篇 |
2022年 | 62篇 |
2021年 | 98篇 |
2020年 | 46篇 |
2019年 | 81篇 |
2018年 | 119篇 |
2017年 | 99篇 |
2016年 | 154篇 |
2015年 | 222篇 |
2014年 | 275篇 |
2013年 | 410篇 |
2012年 | 453篇 |
2011年 | 440篇 |
2010年 | 277篇 |
2009年 | 208篇 |
2008年 | 343篇 |
2007年 | 341篇 |
2006年 | 323篇 |
2005年 | 322篇 |
2004年 | 285篇 |
2003年 | 231篇 |
2002年 | 247篇 |
2001年 | 56篇 |
2000年 | 50篇 |
1999年 | 56篇 |
1998年 | 51篇 |
1997年 | 37篇 |
1996年 | 43篇 |
1995年 | 40篇 |
1994年 | 31篇 |
1993年 | 41篇 |
1992年 | 32篇 |
1991年 | 18篇 |
1990年 | 19篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 16篇 |
1986年 | 14篇 |
1985年 | 13篇 |
1984年 | 22篇 |
1983年 | 16篇 |
1982年 | 7篇 |
1981年 | 16篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1965年 | 5篇 |
排序方式: 共有5733条查询结果,搜索用时 15 毫秒
851.
Serum From Advanced Heart Failure Patients Promotes Angiogenic Sprouting and Affects the Notch Pathway in Human Endothelial Cells
下载免费PDF全文
![点击此处可从《Journal of cellular physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Micaela Pannella Cristiana Caliceti Francesca Fortini Giorgio Aquila Francesco Vieceli Dalla Sega Antonio Pannuti Cinzia Fortini Marco Bruno Morelli Alessandro Fucili Gloria Francolini Rebecca Voltan Paola Secchiero Giovanni Dinelli Emanuela Leoncini Manuela Ferracin Silvana Hrelia Lucio Miele Paola Rizzo 《Journal of cellular physiology》2016,231(12):2700-2710
852.
853.
854.
Functional characterization of a gene locus from an uncultured gut Bacteroides conferring xylo‐oligosaccharides utilization to Escherichia coli
下载免费PDF全文
![点击此处可从《Molecular microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
855.
856.
857.
Bertelli M Cecchin S Lapucci C de Gemmis P Danieli D d'Amore ES Buttolo L Giunta F Mortini P Pandolfo M 《Biochimica et biophysica acta》2007,1772(1):15-20
The chloride channel 2 (CLCN2) gene codes for a protein organized in N- and C-terminal regions with regulatory functions and a transmembrane region which forms the ring of the pore. Mutations in the gene have previously been described in patients with idiopathic familial epilepsy. In this study we looked for new isoforms of CLCN2 and we estimated expression levels by real time PCR in brain tissue containing epileptic foci. Samples used in this study were first analyzed and selected to exclude mutations in the coding region of the gene. Four isoforms (skipping exons 3, 16, 22 and 6/7) were identified and quantified by Real Time PCR and compared with total expression of the gene. Expression of the region common to all CLCN2 isoforms was 50% less in epilepsy-associated brain tissue than in controls. The ratio of the various isoforms was slightly greater in epileptic than control tissue. The greatest difference was recorded in the temporal lobe for the isoform with skipped exon 22. Analysis of these isoforms in brain tissue containing epileptic foci suggests that CLCN2 could be implicated in epilepsy, even in the absence of mutations. 相似文献
858.
Gubellini F Francia F Turina P Lévy D Venturoli G Melandri BA 《Biochimica et biophysica acta》2007,1767(11):1340-1352
The density distribution of photosynthetic membrane vesicles (chromatophores) from Rhodobacter capsulatus has been studied by isopicnic centrifugation. The average vesicle diameters, examined by electron microscopy, varied between 61 and 72 nm in different density fractions (70 nm in unfractionated chromatophores). The ATP synthase catalytic activities showed maxima displaced toward the higher density fractions relative to bacteriochlorophyll, resulting in higher specific activities in those fractions (about threefold). The amount of ATP synthase, measured by quantitative Western blotting, paralleled the catalytic activities. The average number of ATP synthases per chromatophore, evaluated on the basis of the Western blotting data and of vesicle density analysis, ranged between 8 and 13 (10 in unfractionated chromatophores). Poisson distribution analysis indicated that the probability of chromatophores devoid of ATP synthase was negligible. The effects of ATP synthase inhibition by efrapeptin on the time course of the transmembrane electric potential (evaluated as carotenoid electrochromic response) and on ATP synthesis were studied comparatively. The ATP produced after a flash and the total charge associated with the proton flow coupled to ATP synthesis were more resistant to efrapeptin than the initial value of the phosphorylating currents, indicating that several ATP synthases are fed by protons from the same vesicle. 相似文献
859.
860.
Induction by Hypoxia of Heterologous-Protein Production with the KlPDC1 Promoter in Yeasts
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Andrea Camattari Michele M. Bianchi Paola Branduardi Danilo Porro Luca Brambilla 《Applied microbiology》2007,73(3):922-929
The control of promoter activity by oxygen availability appears to be an intriguing system for heterologous protein production. In fact, during cell growth in a bioreactor, an oxygen shortage is easily obtained simply by interrupting the air supply. The purpose of our work was to explore the possible use of hypoxic induction of the KlPDC1 promoter to direct heterologous gene expression in yeast. In the present study, an expression system based on the KlPDC1 promoter was developed and characterized. Several heterologous proteins, differing in size, origin, localization, and posttranslational modification, were successfully expressed in Kluyveromyces lactis under the control of the wild type or a modified promoter sequence, with a production ratio between 4 and more than 100. Yields were further optimized by a more accurate control of hypoxic physiological conditions. Production of as high as 180 mg/liter of human interleukin-1β was obtained, representing the highest value obtained with yeasts in a lab-scale bioreactor to date. Moreover, the transferability of our system to related yeasts was assessed. The lacZ gene from Escherichia coli was cloned downstream of the KlPDC1 promoter in order to get β-galactosidase activity in response to induction of the promoter. A centromeric vector harboring this expression cassette was introduced in Saccharomyces cerevisiae and in Zygosaccharomyces bailii, and effects of hypoxic induction were measured and compared to those already observed in K. lactis cells. Interestingly, we found that the induction still worked in Z. bailii; thus, this promotor constitutes a possible inducible system for this new nonconventional host. 相似文献