全文获取类型
收费全文 | 313篇 |
免费 | 21篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 16篇 |
2013年 | 22篇 |
2012年 | 20篇 |
2011年 | 27篇 |
2010年 | 11篇 |
2009年 | 10篇 |
2008年 | 15篇 |
2007年 | 8篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 11篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 8篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1965年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有334条查询结果,搜索用时 15 毫秒
71.
Anna Maria Mercuri Carla Alberta Accorsi Marta Bandini Mazzanti Giovanna Bosi Andrea Cardarelli Donato Labate Marco Marchesini Giuliana Trevisan Grandi 《Vegetation History and Archaeobotany》2006,16(1):43-60
The paper presents a synthesis of the on-site archaeobotanical investigations of the Terramara di Montale, one of the most important sites of the Terramara cultural system which characterised the Po Plain in the Middle-Late Bronze Age (1650–1200 b.c.). Samples for pollen analysis and macroremains, including seed/fruit and wood/charcoal records, were collected from stratigraphic sequences and occupation levels during the excavations 1996–2001. The results permitted the reconstruction of the main characteristics of the landscape which at the onset of the Terramara rapidly passed from a natural, more forested landscape with mixed oak wood and conifers to a more open and anthropic landscape characterised by cereal fields, pastures and meadows. People felled oaks and other trees such as Populus/Salix and Fraxinus to make piles or walls for houses. Wood from these species was also recorded as charcoal in the hearths. Palynological and carpological data show that the inhabitants of the Terramara largely founded their economy on cereals (mainly Triticum aestivum/durum, T. dicoccum and Hordeum vulgare). They also grew a few legumes (Vicia faba var. minor, Vicia sp. and Lens culinaris). There was also grazing by domestic animals, mainly ovicaprines but also pigs and cattle, and these were fed exploiting wild plants such as Carpinus. In the paper the four main steps of the history of the Terramara are described (before the Terramara, the onset, the Terramara phase, the decline) during which both human influence and climatic changes were important. At the onset of the Terramara (around 1600 b.c.) a warm and possibly dry phase occurred. The intense use of the territory and a climatic deterioration at around 1300 b.c. might have triggered the decline of the Terramara di Montale. 相似文献
72.
del Olmo E Barboza B Ybarra MI López-Pérez JL Carrón R Sevilla MA Boselli C San Feliciano A 《Bioorganic & medicinal chemistry letters》2006,16(10):2786-2790
Several series of dihydrostilbenamide, imidazo[2,1-a]isoindole, pyrimido[2,1-a]isoindole and phthalazinone derivatives were obtained and their vasorelaxant activity was measured on isolated rat aorta rings pre-contracted with phenylephrine (10(-5)M). Some phthalazinones attained, practically, the total relaxation of the organ at micromolar concentrations. For the most potent compound 9h (EC(50)=0.43microM) the affinities for alpha(1A), alpha(1B) and alpha(1D) adrenergic sub-receptors were determined. 相似文献
73.
Dene R. Littler Stephen J. Harrop Juanita M. Phang Lele Jiang Michele Mazzanti Samuel N. Breit 《FEBS letters》2010,584(10):2093-10897
Chloride intracellular channel proteins (CLICs) are distinct from most ion channels in that they have both soluble and integral membrane forms. CLICs are highly conserved in chordates, with six vertebrate paralogues. CLIC-like proteins are found in other metazoans. CLICs form channels in artificial bilayers in a process favoured by oxidising conditions and low pH. They are structurally plastic, with CLIC1 adopting two distinct soluble conformations. Phylogenetic and structural data indicate that CLICs are likely to have enzymatic function. The physiological role of CLICs appears to be maintenance of intracellular membranes, which is associated with tubulogenesis but may involve other substructures. 相似文献
74.
75.
Littler DR Harrop SJ Fairlie WD Brown LJ Pankhurst GJ Pankhurst S DeMaere MZ Campbell TJ Bauskin AR Tonini R Mazzanti M Breit SN Curmi PM 《The Journal of biological chemistry》2004,279(10):9298-9305
Most proteins adopt a well defined three-dimensional structure; however, it is increasingly recognized that some proteins can exist with at least two stable conformations. Recently, a class of intracellular chloride ion channel proteins (CLICs) has been shown to exist in both soluble and integral membrane forms. The structure of the soluble form of CLIC1 is typical of a soluble glutathione S-transferase superfamily protein but contains a glutaredoxin-like active site. In this study we show that on oxidation CLIC1 undergoes a reversible transition from a monomeric to a non-covalent dimeric state due to the formation of an intramolecular disulfide bond (Cys-24-Cys-59). We have determined the crystal structure of this oxidized state and show that a major structural transition has occurred, exposing a large hydrophobic surface, which forms the dimer interface. The oxidized CLIC1 dimer maintains its ability to form chloride ion channels in artificial bilayers and vesicles, whereas a reducing environment prevents the formation of ion channels by CLIC1. Mutational studies show that both Cys-24 and Cys-59 are required for channel activity. 相似文献
76.
Current knowledge of iron metabolism 总被引:1,自引:0,他引:1
Boccio J Salgueiro J Lysionek A Zubillaga M Weill R Goldman C Caro R 《Biological trace element research》2003,92(3):189-211
Iron plays many roles in human physiology. In this article, we summarize the basic and current knowledge of this essential
micronutrient on human metabolism. 相似文献
77.
Canosa LF Pozzi AG Rosemblit C Ceballos NR 《The Journal of steroid biochemistry and molecular biology》2003,85(2-5):227-233
In Bufo arenarum, androgen biosynthesis occurs through a complete 5-ene pathway, including 5-androstane-3β,17β-diol as the immediate precursor of testosterone. Besides, steroidogenesis changes during the breeding period, turning from androgens to C21-steroids such as 5-pregnan-3,20-diol, 3-hydroxy-5-pregnan-20-one and 5-pregnan-3,20-dione. In B. arenarum, steroid hormones are not involved in hCG-induced spermiation, suggesting that the steroidogenic shift to C21-steroids during the breeding be not related to spermiation. The activity of 17-hydroxylase-C17–20 lyase (CypP450c17) decreases during the reproductive season, suggesting that this enzyme would represent a key enzyme in the regulation of seasonal changes. However, the increase in the affinity for pregnenolone of 3β-hydroxysteroid dehydrogenase (3HSD)/isomerase could also be involved. Moreover, the reduction in CypP450c17 leading to a reduction in C19-steroids, among them dehydroepiandrosterone (DHE), would contribute to the conversion of pregnenolone into progesterone, avoiding the non-competitive inhibition exerted by DHE on this transformation. Additionally, CypP450c17 possesses a higher affinity for pregnenolone than for progesterone, explaining the predominance of the 5-ene pathway for testosterone biosynthesis. Animals in reproductive condition showed a significant reduction in circulating androgens, enhancing the physiological relevance of all the in vitro results. The in vitro effects of mGnRH and hrFSH on testicular steroidogenesis revealed that both hormones inhibited CypP450c17 activity. In summary, these results demonstrate that, in B. arenarum, the change in testicular steroidogenesis during the reproductive period could be partially due to an FSH and GnRH-induced decrease in CypP450c17 activity. 相似文献
78.
Electron spin resonance studies of the effects of lipids on the environment of proteins in mitochondrial membranes 总被引:1,自引:0,他引:1
G Lenaz G Curatola L Mazzanti G Zolese G Ferretti 《Archives of biochemistry and biophysics》1983,223(2):369-380
The physical state of mitochondrial membranes has been investigated by means of stearic acid spin labels and of a maleimide spin label covalently bound to protein sulfhydryl groups. Stearic acid spin labels 5-NS and 16-NS show that n-butanol enhances the lipid fluidity of mitochondrial membranes in the whole temperature range between 4 and 37 degrees C; the effects in the hydrophobic membrane core, probed by 16-NS, are already apparent at 10 mM butanol. In liposomes formed of mitochondrial phospholipids, a fluidizing effect appears only at much higher concentration. Such results are compatible with the idea that butanol destabilizes lipid-protein interactions. On the other hand, the ratio between weakly and strongly immobilized SH groups probed by maleimide spin label is only slightly affected in the temperature range of 4-37 degrees C by addition of high concentrations of n-butanol, indicating that the environments probed are stable to agents inducing fluidity changes in the lipids. There are, however, indications that the environment probed by maleimide is affected by lipids, since the spin label, when bound to lipid-depleted mitochondria, becomes more immobilized, reconstitution of such lipid-depleted membranes with phospholipids restores the original spectra. 相似文献
79.
L Mazzanti G Curatola G Zolese E Bertoli G Lenaz 《Bollettino della Società italiana di biologia sperimentale》1979,55(6):506-510
In this communication we report the effects of general anesthetics on the mobility and order of spin labeled stearic acid derivatives in synaptic membranes and in bilayers formed from the lipids extracted therefrom. The anesthetics studied abolish the immobilization induced by synaptic membrane proteins on the membrane lipids : this effect, observed particularly in the bilayer core, is interpreted as a labilization of lipid-protein interactions induced by anesthetics. 相似文献
80.
G Zolese G Curatola L Mazzanti B Leporoni G Lenaz 《Bollettino della Società italiana di biologia sperimentale》1979,55(6):511-516
General anesthetics inhibit erythrocyte membrane-bound acetylcholinesterase. Release of the membrane-bound enzyme by sonication into a soluble form induces a loss of sensitivity to anesthetics. Reconstitution of the solubilized enzyme with phospholipids restores its inhibition by anesthetics. The results suggest that anesthetic inhibition of acetylcholinesterase is mediated through the lipid bilayer. 相似文献