全文获取类型
收费全文 | 1818篇 |
免费 | 140篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 15篇 |
2021年 | 36篇 |
2020年 | 32篇 |
2019年 | 41篇 |
2018年 | 32篇 |
2017年 | 28篇 |
2016年 | 53篇 |
2015年 | 95篇 |
2014年 | 120篇 |
2013年 | 136篇 |
2012年 | 185篇 |
2011年 | 236篇 |
2010年 | 136篇 |
2009年 | 75篇 |
2008年 | 122篇 |
2007年 | 139篇 |
2006年 | 111篇 |
2005年 | 79篇 |
2004年 | 88篇 |
2003年 | 59篇 |
2002年 | 60篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有1958条查询结果,搜索用时 15 毫秒
1.
2.
Miodrag Petrović Ilijana Grigorov Tanja Milosavljević Desanka Bogojević Snežana Ŝekularac Ljiljana Ševaljević 《Molecular biology reports》1996,23(2):79-85
A 29 kD soluble rat liver nucleoprotein (p29) has increased binding affinity for the hormone responsive element (RE) of the rat haptoglobin (Hp) gene during the acute-phase reaction. In this work the possibility of its structural and functional homology to the high mobility group 1 (HMG1) nonhistone protein constituent of chromatin was examined. The results of two-dimensional gel electrophoresis, Southwestern and Western immunoblot analyses, showed that p29 and HMG1 are homologous protein species. On the basis of in vitro and in vivo phosphorylation/dephosphorylation experiments, we discuss the modulatory role of phosphate groups in view of the structure and function of p29. 相似文献
3.
By screening total human DNA with probes derived from the small polydisperse circular (spc) DNA fraction of cultured human cells, we identified three clones that carry long stretches of -satellite DNA. Further experiments have shown that the three sequences belong to at least two different -satellite subfamilies, which are characterized by different higher order subunits. Members of one of these subfamilies are located in the cytological satellites of all acrocentric chromosomes, whereas members of another are located on the short arms of the acrocentrics on both sides of the stalk regions and also in the centromeric regions of chromosomes 1 and 9. This is the first time that -satellite sequences obtained from the spcDNA of human cells have been assigned to -satellite subfamilies that are organized as long arrays of tandemly arranged higher order monomers. This indicates that -satellite sequences can be excised from their chromosomal loci via intrastrand-recombination processes.This paper is dedicated to Prof. Dr. Ulrich Wolf on his 60th birthday, January 1993 相似文献
4.
Hannah Maus Gerald Hinze Stefan Josef Hammerschmidt Thomas Basché Tanja Schirmeister 《Protein science : a publication of the Protein Society》2023,32(1):e4526
Ligand binding to proteins often is accompanied by conformational transitions. Here, we describe a competition assay based on single molecule Förster resonance energy transfer (smFRET) to investigate the ligand-induced conformational changes of the dengue virus (DENV) NS2B-NS3 protease, which can adopt at least two different conformations. First, a competitive ligand was used to stabilize the closed conformation of the protease. Subsequent addition of the allosteric inhibitor reduced the fraction of the closed conformation and simultaneously increased the fraction of the open conformation, demonstrating that the allosteric inhibitor stabilizes the open conformation. In addition, the proportions of open and closed conformations at different concentrations of the allosteric inhibitor were used to determine its binding affinity to the protease. The KD value observed is in accordance with the IC50 determined in the fluorometric assay. Our novel approach appears to be a valuable tool to study conformational transitions of other proteases and enzymes. 相似文献
5.
Tanja Albrecht Sophie Haebel Anke Koch Ulrike Krause Nora Eckermann Martin Steup 《European journal of biochemistry》2004,271(20):3978-3989
Saccharomyces cerevisiae possesses two glycogenin isoforms (designated as Glg1p and Glg2p) that both contain a conserved tyrosine residue, Tyr232. However, Glg2p possesses an additional tyrosine residue, Tyr230 and therefore two potential autoglucosylation sites. Glucosylation of Glg2p was studied using both matrix-assisted laser desorption ionization and electrospray quadrupole time of flight mass spectrometry. Glg2p, carrying a C-terminal (His6) tag, was produced in Escherichia coli and purified. By tryptic digestion and reversed phase chromatography a peptide (residues 219-246 of the complete Glg2p sequence) was isolated that contained 4-25 glucosyl residues. Following incubation of Glg2p with UDPglucose, more than 36 glucosyl residues were covalently bound to this peptide. Using a combination of cyanogen bromide cleavage of the protein backbone, enzymatic hydrolysis of glycosidic bonds and reversed phase chromatography, mono- and diglucosylated peptides having the sequence PNYGYQSSPAM were generated. MS/MS spectra revealed that glucosyl residues were attached to both Tyr232 and Tyr230 within the same peptide. The formation of the highly glucosylated eukaryotic Glg2p did not favour the bacterial glycogen accumulation. Under various experimental conditions Glg2p-producing cells accumulated approximately 30% less glycogen than a control transformed with a Glg2p lacking plasmid. The size distribution of the glycogen and extractable activities of several glycogen-related enzymes were essentially unchanged. As revealed by high performance anion exchange chromatography, the intracellular maltooligosaccharide pattern of the bacterial cells expressing the functional eukaryotic transgene was significantly altered. Thus, the eukaryotic glycogenin appears to be incompatible with the bacterial initiation of glycogen biosynthesis. 相似文献
6.
7.
Birgit Sklorz und Tanja Volz 《Journal of Ornithology》1990,131(2):157-160
Zusammenfassung Frisch geschlüpften Hühnerküken wurden schwarz-gelb geringelte und grüne Attrappen sowie Mehlwürmer angeboten, um zu testen, ob eine angeborene Hemmung gegenüber warnfarbiger Beute besteht. Unsere Küken zeigten sowohl eine eindeutige Präferenz für schwarzgelb geringelte Attrappen als auch für Mehlwürmer. Daraus schließen wir, daß es keine genetisch fixierte Hemmung gegenüber schwarz-gelber Ringelung, d. h. auffälliger Beute gibt.
Innate and learned preferences in food selection of chicken (Gallus domesticus)
Summary In reference to the experiment ofSchuler &Hesse (1985), recently hatched chicken were offered a choise between warningly coloured black and yellow and nonwarningly coloured green prey. We can not support their hypothesis of a genetically fixed pecking inhibition towards prey with warning colouration. The chicken directed their first peck at the warningly coloured ones and they ate them at a significantly higher rate. These results support the idea ofGittleman &Harvey (1980), that chicken prefer conspicuous prey.相似文献
8.
9.
10.
Inken Kirschbaum Joana Straub Stephanie Gest Martin Holtmann Tanja Legenbauer 《Chronobiology international》2018,35(1):101-110
Chronotherapeutics are well established for the treatment of depression and associated sleeping problems in adults. However, effects are still understudied in adolescents. Two pilot studies highlighted the crucial role of sleep when it comes to the treatment of depression, by means of chronotherapeutics, in adolescents. The aim of the present study was to investigate the role of adjunctive wake therapy (WT) in addition to bright light therapy (BLT) with respect to sleep behaviors. In the present study, 62 depressed inpatients (aged 13–18 years; diagnosed with Beck Depression Inventory Revision) were randomly assigned to two groups: BLT only (BLT-group) and a combination of BLT and WT (COMB-group). After one night of WT adolescents in the COMB-group revealed longer sleep durations, time in bed, advanced sleep onset, less wakes during night and an improved sleep efficiency. However, one night of WT plus BLT had no additional effect on sleep parameters compared with BLT-group in the long run. Therefore, future studies should assess whether more nights of WT might lead to more sustainable effects. 相似文献