全文获取类型
收费全文 | 1346篇 |
免费 | 126篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 35篇 |
2020年 | 29篇 |
2019年 | 29篇 |
2018年 | 54篇 |
2017年 | 34篇 |
2016年 | 37篇 |
2015年 | 84篇 |
2014年 | 68篇 |
2013年 | 91篇 |
2012年 | 117篇 |
2011年 | 89篇 |
2010年 | 61篇 |
2009年 | 62篇 |
2008年 | 95篇 |
2007年 | 74篇 |
2006年 | 79篇 |
2005年 | 56篇 |
2004年 | 43篇 |
2003年 | 47篇 |
2002年 | 53篇 |
2001年 | 15篇 |
2000年 | 13篇 |
1999年 | 16篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 14篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1974年 | 2篇 |
1968年 | 2篇 |
1964年 | 3篇 |
排序方式: 共有1472条查询结果,搜索用时 15 毫秒
41.
42.
Volumetric properties underlying ligand binding in a monomeric hemoglobin: A high-pressure NMR study
Mariano Dellarole Christian Roumestand Catherine Royer Juliette T.J. Lecomte 《Biochimica et Biophysica Acta - Proteins and Proteomics》2013,1834(9):1910-1922
The 2/2 hemoglobin of the cyanobacterium Synechococcus sp. PCC 7002, GlbN, coordinates the heme iron with two histidines and exists either with a b heme or with a covalently attached heme. The binding of exogenous ligands displaces the distal histidine and induces a conformational rearrangement involving the reorganization of internal void volumes. The formation of passageways within the resulting conformation is thought to facilitate ligand exchange and play a functional role. Here we monitored the perturbation induced by pressure on the ferric bis-histidine and cyanide-bound states of GlbN using 1H–15N HSQC NMR spectroscopy. We inspected the outcome with a statistical analysis of 170 homologous 2/2 hemoglobin sequences. We found that the compression landscape of GlbN, as represented by the variation of an average chemical shift parameter, was highly sensitive to ligand swapping and heme covalent attachment. Stabilization of rare conformers was observed at high pressures and consistent with cavity redistribution upon ligand binding. In all states, the EF loop was found to be exceptionally labile to pressure, suggesting a functional role as a semi-flexible hinge between the adjacent helices. Finally, coevolved clusters presented a common pattern of compensating pressure responses. The high-pressure dissection combined with protein sequence analysis established locations with volumetric signatures relevant to residual communication of 2/2 hemoglobins. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins. 相似文献
43.
M. Rosario Darquier Cecilia F. Bessega Mariano Cony Juan C. Vilardi Beatriz O. Saidman 《Tree Genetics & Genomes》2013,9(1):307-320
Prosopis flexuosa is an arboreal Leguminosae that grows in arid and semiarid temperate zones of Argentina, in the Monte eco-region. It is a promising native forest species for recovering arid and semiarid regions because it plays an important role in erosion control as well as in soil fertility. Furthermore, it provides diverse economical resources. The main challenge to the forestry sector is finding a balance between production and forest protection. For this purpose, it is necessary to gather information about genetic parameters. In this study, we measured the distribution of the variation of 14 quantitative traits in an experimental half-sib stand, where families are representative of hierarchically structured populations. We applied a multivariate extension of the classical Q ST –F ST neutrality test to determine the relative importance of drift versus selection in the distribution of genetic variability. We found strong evidence that different selective regimes act on different traits and that selection favors different optima in each sampling site. The selection to different optima is much stronger among than within provenances. This result helps explain the possible causes for the regional variation observed in P. flexuosa and to define the management units and the evolutionarily significant units for this species. 相似文献
44.
Carla Rossini Crepaldi Phelipe Augusto Mariano Vitale Andrea Cristina Tesch Hélen Julie Laure José César Rosa Marcelo de Cerqueira César 《Mitochondrion》2013,13(6):823-830
Two types of binding sites for hexokinase, designated as Type A or Type B sites, have been shown to coexist on brain mitochondria. The ratio of these sites varies between species.HK1 attaches by reversibly binding to the voltage dependent anion channel (VDAC). Regarding the nature of hexokinase binding sites, we investigated if it was linked to distinct VDAC interactomes. We approached this question by 2D BN/SDS-PAGE of mitochondria, followed by mass spectrometry.Our results are consistent with the possibility that the ratio of Type A/Type B sites is due to differential VDAC interactions in bovine and rat neuronal cells. 相似文献
45.
Elena González-Sánchez Juan Martín-Caballero Juana María Flores Javier Hernández-Losa Ma ángeles Montero Javier Cortés Roso Mares Mariano Barbacid Juan A. Recio 《PloS one》2013,8(6)
Aberrant activation of MAP kinase signaling pathway and loss of tumor suppressor LKB1 have been implicated in lung cancer development and progression. Although oncogenic KRAS mutations are frequent, BRAF mutations (BRAFV600E) are found in 3% of human non-small cell lung cancers. Contrary to KRAS mutant tumors, BRAFV600E-induced tumors are benign adenomas that fail to progess. Interestingly, loss of tumor supressor LKB1 coexists with KRAS oncogenic mutations and synergizes in tumor formation and progression, however, its cooperation with BRAFV600E oncogene is unknown. Our results describe a lung cell population in neonates mice where expression of BRAFV600E leads to lung adenoma development. Importantly, expression of BRAFV600E concomitant with the loss of only a single-copy of Lkb1, overcomes senencence–like features of BRAFV600E-mutant adenomas leading malignization to carcinomas. These results posit LKB1 haploinsufficiency as a risk factor for tumor progression of BRAFV600E mutated lung adenomas in human cancer patients. 相似文献
46.
Darío C. Colautti Leandro Miranda Mariano Gonzalez-Castro Vanina Villanova Carlos A. Strüssmann Miguel Mancini Tomas Maiztegui Gustavo Berasain Ricardo Hattori Fabian Grosman Pablo Sanzano Ismael Lozano Sabina L. Vegh Victor Salinas Omar Del Ponti Pamela del Fresno Priscila Minotti Yoji Yamamoto Claudio R. M. Baigún 《Journal of fish biology》2020,96(1):202-216
In South America, the order Atheriniformes includes the monophyletic genus Odontesthes with 20 species that inhabit freshwater, estuarine and coastal environments. Pejerrey Odontesthes argentinensis is widely distributed in coastal and estuarine areas of the Atlantic Ocean and is known to foray into estuaries of river systems, particularly in conditions of elevated salinity. However, to our knowledge, a landlocked self-sustaining population has never been recorded. In this study, we examined the pejerrey population of Salada de Pedro Luro Lake (south-east of Buenos Aires Province, Argentina) to clarify its taxonomic identity. An integrative taxonomic analysis based on traditional meristic, landmark-based morphometrics and genetic techniques suggests that the Salada de Pedro Luro pejerrey population represents a novel case of physiological and morphological adaptation of a marine pejerrey species to a landlocked environment and emphasises the environmental plasticity of this group of fishes. 相似文献
47.
Vanessa Castelli Francesco Melani Claudio Ferri Michele d'Angelo Mariano Catanesi Davide Grassi Elisabetta Benedetti Antonio Giordano Annamaria Cimini Giovambattista Desideri 《Journal of cellular biochemistry》2020,121(12):4862-4869
Oxidative stress is considered the common effector of the cascade of degenerative events in many neurological conditions. Thus, in this paper we tested different nutraceuticals in H2O2 in vitro model to understand if could represent an adjuvant treatment for neurological diseases. In this study, nutraceuticals bacopa, lycopene, astaxanthin, and vitamin B12 were used alone or in combination in human neuronal differentiated SH-SY5Y cells upon hydrogen peroxide-induced injury and neuroprotective, neuronal death pathways were analyzed. The nutraceuticals analyzed were able to protect H2O2 cytotoxic effects, through increasing cell viability and proteins involved in neuroprotection pathways and restoring proteins involved in cell death pathways. On this basis, it is possible to propose the use of these compounds as dietary supplement for the prevention or as adjuvant to the only symptomatic treatments so far available for neurodegenerative diseases. 相似文献
48.
Altúzar-Molina Alma Lozano Luis Ortíz-Berrocal Marlene Ramírez Mario Martínez Lourdes de Lourdes Velázquez-Hernández María Dhar-Ray Swatismita Silvente Sonia Mariano Néstor Shishkova Svetlana Hernández Georgina Reddy Pallavolu M. 《Plant Molecular Biology Reporter》2020,38(2):262-281
Plant Molecular Biology Reporter - Legumes form symbiosis with rhizobia, which fix nitrogen for the benefit of host plant in return for carbon resources. Development of this unique symbiosis in... 相似文献
49.
Mariano Alvarez Andrew Bleich Kathleen Donohue 《Evolution; international journal of organic evolution》2020,74(10):2265-2280
Phenotypes respond to environments experienced directly by an individual, via phenotypic plasticity, or to the environment experienced by ancestors, via transgenerational environmental effects. The adaptive value of environmental effects depends not only on the strength and direction of the induced response but also on how long the response persists within and across generations, and how stably it is expressed across environments that are encountered subsequently. Little is known about the genetic basis of those distinct components, or even whether they exhibit genetic variation. We tested for genetic differences in the inducibility, temporal persistence, and environmental stability of transgenerational environmental effects in Arabidopsis thaliana. Genetic variation existed in the inducibility of transgenerational effects on traits expressed across the life cycle. Surprisingly, the persistence of transgenerational effects into the third generation was uncorrelated with their induction in the second generation. Although environmental effects for some traits in some genotypes weakened over successive generations, others were stronger or even in the opposite direction in more distant generations. Therefore, transgenerational effects in more distant generations are not merely caused by the retention or dissipation of those expressed in prior generations, but they may be genetically independent traits with the potential to evolve independently. 相似文献
50.
Ayelen Tschopp Franco Cristiani Nestor Aníbal García Enrique Alberto Crespo Mariano Alberto Coscarella 《Journal of fish biology》2020,97(3):656-667
Overexploitation of marine communities can lead to modifications in the structure of the food web and can force organisms like elasmobranchs to change their feeding habits. To evaluate the impact that fisheries have on food webs and on the interactions between species, it is necessary to describe and quantify the diet of the species involved and follow it through time. This study compares the diet of five skate species using the data obtained from the by-catch of the Argentine hake (Merluccius hubbsi) fishery in north and central Patagonia, Argentina. Diet composition was assessed by analysing the digestive tract contents and trophic overlapping between species of the genus Bathyraja: Bathyraja albomaculata, Bathyraja brachyurops, Bathyraja macloviana, Bathyraja magellanica and Bathyraja multispinis. A total of 184 stomachs were analysed. The diets of B. albomaculata and B. macloviana mainly comprised annelids, whereas that of B. brachyurops primarily comprised fish, including hake heads discarded by the fishery. The diets of B. magellanica and B. multispinis were largely based on crustaceans. Despite the morphological similarities and their shared preference for benthic habitats, no complete diet overlaps were found between the different species. These results suggest that these skate species have undergone a process of diet specialisation. This is a common feeding strategy that occurs to successfully eliminate competition when resources are limited, which corresponds to the conditions found in an environment being affected by the pressures of overfishing. 相似文献