全文获取类型
收费全文 | 239篇 |
免费 | 8篇 |
出版年
2021年 | 4篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 14篇 |
2011年 | 10篇 |
2010年 | 12篇 |
2009年 | 14篇 |
2008年 | 12篇 |
2007年 | 8篇 |
2006年 | 16篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
排序方式: 共有247条查询结果,搜索用时 46 毫秒
161.
Saenko IuV Shutov AM Napalkova SM 《Radiatsionnaia biologiia, radioecologiia / Rossi?skaia akademiia nauk》2011,51(6):677-683
The dynamics of radiation-induced oxidative and nitrative stress, the source of oxygen and nitrogen reactive species in cancer cell line K562 and the role of mitochondria in these processes have been studied. The study was performed using K562 leukemia cell cultures. Intracellular concentration of reactive oxygen species (ROS), nitrogen oxide, and the mitochondrial potential were analyzed after 15, 30 min, 1, 4, 8, 12, 24, and 48 h after irradiation by X-rays at a dose of 4 and 12 Gy. Radiation-induced generation of ROS in K562 cells has two time peaks, the first peak was recorded after 30 min and the second 24 h after exposure to X-rays. Mitochondria are responsible for the increase of the ROS concentration in the period of 12-48 h after irradiation. The increase in ROS concentrations is accompanied by the increase of the mitochondrial potential. The intracellular concentration of nitric oxide begins to grow 8 h after exposure. The increase in the mitochondria-dependent ROS production is accompanied by the increase in the intracellular concentration of nitric oxide. 相似文献
162.
163.
JOSÉ ARTURO ALCÁNTARA‐RODRÍGUEZ JORGE CIROS‐PÉREZ ELIZABETH ORTEGA‐MAYAGOITIA CARMEN R. SERRANIA‐SOTO ELÍAS PIEDRA‐IBARRA 《Freshwater Biology》2012,57(4):728-740
1. Salinity is a strong selective force for many aquatic organisms, affecting both ecological and evolutionary processes. Most of our knowledge on the effects of salinity on rotifers in the Brachionus plicatilis species complex is based mainly on populations from waterbodies that experience broad environmental changes both seasonally and annually. We tested the hypothesis that, despite the supposedly high potential for gene flow among rotifers inhabiting neighbouring environments, constant salinity has promoted local adaptation, genetic population divergence and even cryptic speciation in B. plicatilis complex populations from three deep maar lakes of distinct salinities [1.1, 6.5 and 9.0 g L?1 total dissolved solids (TDS)] in Central Mexico. 2. To look for local adaptation, we performed common garden experiments to test the effect of different salinities on population density and intrinsic growth rate (r). Then, we evaluated the genetic divergence by sequencing the cytochrome c oxidase subunit I (COI) gene and performed reproductive trials to assess the potential gene flow among the three populations and with other closely related B. plicatilis complex species. 3. We confirmed that the rotifer populations have phenotypic plasticity in tolerance of salinity, but only rotifers from the least saline lake are adapted to low salinity. Among the populations, sequence divergence at COI was very low (just a single haplotype was found), suggesting a persistent founder effect from a relatively recent single colonisation event and a subsequent dispersal from one lake to the others, and a very restricted immigration rate. In the phylogenetic analysis, rotifers from this area of Mexico clustered in the same clade with the middle‐sized species Brachionus ibericus and B. sp. ‘Almenara’. Mexican rotifers showed successful recognition, copulation and formation of hybrids among them, but interpopulation breeding with the Spanish B. ibericus and B. sp. ‘Almenara’ was unsuccessful. 4. We conclude that the B. plicatilis complex populations from these three lakes belong to a new biological species not yet described (presently named B. sp. ‘Mexico’). To our knowledge, this is the first report of local adaptation of a natural B. plicatilis complex population living in freshwater conditions (1.1 g L?1 TDS). 相似文献
164.
165.
E. I. Kremneva L. A. Chernikova R. N. Konovalov M. V. Krotenkova I. V. Saenko I. B. Kozlovskaya 《Human physiology》2012,38(1):49-55
Numerous studies on the mechanisms of the motor control carried out in the interests of space medicine resulted in a concept
on the leading role of the support afferent input in the regulation of the postural tonic system in mammals. The implementation
of functional magnetic resonance imaging (fMRI) has permitted in vivo brain mapping during stimulation of the support afferent
input. The goal of this study was to identify activated regions in the brain during mechanical stimulation of the plantar
support zones in different modes using a special Korvit simulator. Twelve healthy volunteers (six women and six men) aged
from 22 to 42 years were studied using fMRI, each of them was scanned once. The fMRI protocol for each subject consisted of
two different blocked paradigms: (1) with the soles of a subject stimulated in an imitated standing mode and (2) with the
soles stimulated in an imitation slow-walking mode. The patterns of activation in each mode were analyzed using the SPM5 statistical
software package for each subject and for the group as a whole. All the paradigms showed significant activation (p
correct < 0. 05 at the cluster level) in the primary somatosensory, premotor, dorsolateral and prefrontal cortices, as well as in
the insula. The involvement of the prefrontal cortex during simulation of standing and a broad involvement of the primary
and secondary sensorimotor cortices during simulation of slow walking were found. 相似文献
166.
167.
168.
Eliana Alves Liliana Costa Carla MB Carvalho Jo?o PC Tomé Maria A Faustino Maria GPMS Neves Augusto C Tomé José AS Cavaleiro ?ngela Cunha Adelaide Almeida 《BMC microbiology》2009,9(1):70
Background
In recent times photodynamic antimicrobial therapy has been used to efficiently destroy Gram (+) and Gram (-) bacteria using cationic porphyrins as photosensitizers. There is an increasing interest in this approach, namely in the search of photosensitizers with adequate structural features for an efficient photoinactivation process. In this study we propose to compare the efficiency of seven cationic porphyrins differing in meso-substituent groups, charge number and charge distribution, on the photodynamic inactivation of a Gram (+) bacterium (Enterococcus faecalis) and of a Gram (-) bacterium (Escherichia coli). The present study complements our previous work on the search for photosensitizers that might be considered good candidates for the photoinactivation of a large spectrum of environmental microorganisms. 相似文献169.
Melarkode S Ramakrishnan Anand Eswaraiah Tania Crombet Patricia Piedra Giselle Saurez Harish Iyer AS Arvind 《MABS-AUSTIN》2009,1(1):41-48
Nimotuzumab is a humanized therapeutic monoclonal antibody against epidermal growth factor receptor (EGFR). Clinical trials are ongoing globally to evaluate nimotuzumab in different indications. Nimotuzumab has been granted approval for use in squamous cell carcinoma of head and neck (SCCHN), glioma and nasopharyngeal cancer in different countries. This review focuses on the unique functional characteristics of nimotuzumab. Also, it discusses the safety and efficacy data obtained from the Phase IIb clinical trial conducted in India in SCCHN. Post marketing surveillance data from Cuba for the use of nimotuzumab in pediatric and adult glioma is also discussed. Overall, nimotuzumab has immense therapeutic potential in cancers of epithelial origin.Key words: nimotuzumab, EGFR, humanized, monoclonal antibody, SCCHN, glioma, overall survival 相似文献
170.
Ruiz J Kouiavskaia D Migliorini M Robinson S Saenko EL Gorlatova N Li D Lawrence D Hyman BT Weisgraber KH Strickland DK 《Journal of lipid research》2005,46(8):1721-1731
Apolipoprotein E (apoE) associates with lipoproteins and mediates their interaction with members of the LDL receptor family. ApoE exists as three common isoforms that have important distinct functional and biological properties. Two apoE isoforms, apoE3 and apoE4, are recognized by the LDL receptor, whereas apoE2 binds poorly to this receptor and is associated with type III hyperlipidemia. In addition, the apoE4 isoform is associated with the common late-onset familial and sporadic forms of Alzheimer's disease. Although the interaction of apoE with the LDL receptor is well characterized, the specificity of other members of this receptor family for apoE is poorly understood. In the current investigation, we have characterized the binding of apoE to the VLDL receptor and the LDL receptor-related protein (LRP). Our results indicate that like the LDL receptor, LRP prefers lipid-bound forms of apoE, but in contrast to the LDL receptor, both LRP and the VLDL receptor recognize all apoE isoforms. Interestingly, the VLDL receptor does not require the association of apoE with lipid for optimal recognition and avidly binds lipid-free apoE. It is likely that this receptor-dependent specificity for various apoE isoforms and for lipid-free versus lipid-bound forms of apoE is physiologically significant and is connected to distinct functions for these receptors. 相似文献