全文获取类型
收费全文 | 387篇 |
免费 | 25篇 |
出版年
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 28篇 |
2014年 | 22篇 |
2013年 | 29篇 |
2012年 | 24篇 |
2011年 | 27篇 |
2010年 | 14篇 |
2009年 | 11篇 |
2008年 | 22篇 |
2007年 | 25篇 |
2006年 | 27篇 |
2005年 | 24篇 |
2004年 | 15篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 4篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1964年 | 2篇 |
1962年 | 1篇 |
1961年 | 3篇 |
1959年 | 1篇 |
1958年 | 1篇 |
1957年 | 2篇 |
1921年 | 1篇 |
排序方式: 共有412条查询结果,搜索用时 15 毫秒
71.
Jack?A?TuszynskiEmail author Philip?Winter Diana?White Chih-Yuan?Tseng Kamlesh?K?Sahu Francesco?Gentile Ivana?Spasevska Sara?Ibrahim?Omar Niloofar?Nayebi Cassandra?DM?Churchill Mariusz?Klobukowski Rabab?M?Abou?El-Magd 《Theoretical biology & medical modelling》2014,11(1):52
A variety of topics are reviewed in the area of mathematical and computational modeling in biology, covering the range of scales from populations of organisms to electrons in atoms. The use of maximum entropy as an inference tool in the fields of biology and drug discovery is discussed. Mathematical and computational methods and models in the areas of epidemiology, cell physiology and cancer are surveyed. The technique of molecular dynamics is covered, with special attention to force fields for protein simulations and methods for the calculation of solvation free energies. The utility of quantum mechanical methods in biophysical and biochemical modeling is explored. The field of computational enzymology is examined. 相似文献
72.
Yuan Pan Sajag Bhattarai Modestos Modestou Arlene V. Drack Dane M. Chetkovich Sheila A. Baker 《PloS one》2014,9(1)
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are cation-selective channels present in retina, brain and heart. The activity of HCN channels contributes to signal integration, cell excitability and pacemaker activity. HCN1 channels expressed in photoreceptors participate in keeping light responses transient and are required for normal mesopic vision. The subcellular localization of HCN1 varies among cell types. In photoreceptors HCN1 is concentrated in the inner segments while in other retinal neurons, HCN1 is evenly distributed though the cell. This is in contrast to hippocampal neurons where HCN1 is concentrated in a subset of dendrites. A key regulator of HCN1 trafficking and activity is tetratricopeptide repeat-containing Rab8b interacting protein (TRIP8b). Multiple splice isoforms of TRIP8b are expressed throughout the brain and can differentially regulate the surface expression and activity of HCN1. The purpose of the present study was to determine which isoforms of TRIP8b are expressed in the retina and to test if loss of TRIP8b alters HCN1 expression or trafficking. We found that TRIP8b colocalizes with HCN1 in multiple retina neurons and all major splice isoforms of TRIP8b are expressed in the retina. Photoreceptors express three different isoforms. In TRIP8b knockout mice, the ability of HCN1 to traffic to the surface of retinal neurons is unaffected. However, there is a large decrease in the total amount of HCN1. We conclude that TRIP8b in the retina is needed to achieve maximal expression of HCN1. 相似文献
73.
74.
Linglin Xie Qiang Fu Teresa M. Ortega Lun Zhou Dane Rasmussen Jacy O’Keefe Ke K. Zhang Stephen K. Chapes 《PloS one》2014,9(1)
Adipose tissue macrophages are a heterogeneous collection of classically activated (M1) and alternatively activated (M2) macrophages. Interleukin 10 (IL-10) is an anti-inflammatory cytokine, secreted by a variety of cell types including M2 macrophages. We generated a macrophage cell line stably overexpressing IL-10 (C2D-IL10) and analyzed the C2D-IL10 cells for several macrophage markers after exposure to adipocytes compared to C2D cells transfected with an empty vector (C2D-vector). C2D-IL10 macrophage cells expressed more CD206 when co-cultured with adipocytes than C2D-vector cells; while the co-cultured cell mixture also expressed higher levels of Il4, Il10, Il1β and Tnf. Since regular C2D cells traffic to adipose tissue after adoptive transfer, we explored the impact of constitutive IL-10 expression on C2D-IL10 macrophages in adipose tissue in vivo. Adipose tissue-isolated C2D-IL10 cells increased the percentage of CD206+, CD301+, CD11c−CD206+ (M2) and CD11c+CD206+ (M1b) on their cell surface, compared to isolated C2D-vector cells. These data suggest that the expression of IL-10 remains stable, alters the C2D-IL10 macrophage cell surface phenotype and may play a role in regulating macrophage interactions with the adipose tissue. 相似文献
75.
Dae Hyun Lee Martijn J. C. Dane Bernard M. van den Berg Margien G. S. Boels Jurgen W. van Teeffelen Renée de Mutsert Martin den Heijer Frits R. Rosendaal Johan van der Vlag Anton Jan van Zonneveld Hans Vink Ton J. Rabelink for the NEO study group 《PloS one》2014,9(5)
Changes in endothelial glycocalyx are one of the earliest changes in development of cardiovascular disease. The endothelial glycocalyx is both an important biological modifier of interactions between flowing blood and the vessel wall, and a determinant of organ perfusion. We hypothesize that deeper penetration of erythrocytes into the glycocalyx is associated with reduced microvascular perfusion. The population-based prospective cohort study (the Netherlands Epidemiology of Obesity [NEO] study) includes 6,673 middle-aged individuals (oversampling of overweight and obese individuals). Within this cohort, we have imaged the sublingual microvasculature of 915 participants using sidestream darkfield (SDF) imaging together with a recently developed automated acquisition and analysis approach. Presence of RBC (as a marker of microvascular perfusion) and perfused boundary region (PBR), a marker for endothelial glycocalyx barrier properties for RBC accessibility, were assessed in vessels between 5 and 25 µm RBC column width. A wide range of variability in PBR measurements, with a mean PBR of 2.14 µm (range: 1.43–2.86 µm), was observed. Linear regression analysis showed a marked association between PBR and microvascular perfusion, reflected by RBC filling percentage (regression coefficient β: −0.034; 95% confidence interval: −0.037 to −0.031). We conclude that microvascular beds with a thick (“healthy”) glycocalyx (low PBR), reflects efficient perfusion of the microvascular bed. In contrast, a thin (“risk”) glycocalyx (high PBR) is associated with a less efficient and defective microvascular perfusion. 相似文献
76.
77.
Peishen Zhao TinaMarie Lieu Nicholas Barlow Matthew Metcalf Nicholas Veldhuis Dane D. Jensen Martina Kocan Silvia Sostegni Silke Haerteis Vera Baraznenok Ian Henderson Erik Lindstr?m Raquel Guerrero-Alba Eduardo E. Valdez-Morales Wolfgang Liedtke Peter McIntyre Stephen J. Vanner Christoph Korbmacher Nigel W. Bunnett 《The Journal of biological chemistry》2014,289(52):35858
78.
Dane J. Youtz Michael C. Isfort Clayton M. Eichenseer Timothy D. Nelin Loren E. Wold 《Life sciences》2014
Pathologic and physiologic factors acting on the heart can produce consistent pressure changes, volume overload, or increased cardiac output. These changes may then lead to cardiac remodeling, ultimately resulting in cardiac hypertrophy. Exercise can also induce hypertrophy, primarily physiologic in nature. To determine the mechanisms responsible for each type of remodeling, it is important to examine the heart at the functional unit, the cardiomyocyte. Tests of individual cardiomyocyte function in vitro provide a deeper understanding of the changes occurring within the heart during hypertrophy. Examination of cardiomyocyte function during exercise primarily follows one of two pathways: the addition of hypertrophic inducing agents in vitro to normal cardiomyocytes, or the use of trained animal models and isolating cells following the development of hypertrophy in vivo. Due to the short lifespan of adult cardiomyocytes, a proportionately scant amount of research exists involving the direct stimulation of cells in vitro to induce hypertrophy. These attempts provide the only current evidence, as it is difficult to gather extensive data demonstrating cell growth as a result of in vitro physical stimulation. Researchers have created ways to combine skeletal myocytes with cardiomyocytes to produce functional muscle cells used to repair pathologic heart tissue, but continue to struggle with the short lifespan of these cells. While there have been promising findings regarding the mechanisms that surround cardiac hypertrophy in vitro, the translation of in vitro findings to in vivo function is not consistent. Therefore, the focus of this review is to highlight recent studies that have investigated the effect of exercise on the heart, both in vitro and in vivo. 相似文献
79.
Naturalization and invasion of alien plants: concepts and definitions 总被引:11,自引:0,他引:11
David M. Richardson Petr Pyek Marcel Rejmánek Michael G. Barbour F. Dane Panetta Carol J. West 《Diversity & distributions》2000,6(2):93-107
Abstract. Much confusion exists in the English-language literature on plant invasions concerning the terms 'naturalized' and 'invasive' and their associated concepts. Several authors have used these terms in proposing schemes for conceptualizing the sequence of events from introduction to invasion, but often imprecisely, erroneously or in contradictory ways. This greatly complicates the formulation of robust generalizations in invasion ecology.
Based on an extensive and critical survey of the literature we defined a minimum set of key terms related to a graphic scheme which conceptualizes the naturalization/invasion process. Introduction means that the plant (or its propagule) has been transported by humans across a major geographical barrier. Naturalization starts when abiotic and biotic barriers to survival are surmounted and when various barriers to regular reproduction are overcome. Invasion further requires that introduced plants produce reproductive offspring in areas distant from sites of introduction (approximate scales: > 100 m over < 50 years for taxa spreading by seeds and other propagules; > 6 m/3 years for taxa spreading by roots, rhizomes, stolons or creeping stems). Taxa that can cope with the abiotic environment and biota in the general area may invade disturbed, seminatural communities. Invasion of successionally mature, undisturbed communities usually requires that the alien taxon overcomes a different category of barriers.
We propose that the term 'invasive' should be used without any inference to environmental or economic impact. Terms like 'pests' and 'weeds' are suitable labels for the 50–80% of invaders that have harmful effects. About 10% of invasive plants that change the character, condition, form, or nature of ecosystems over substantial areas may be termed 'transformers'. 相似文献
Based on an extensive and critical survey of the literature we defined a minimum set of key terms related to a graphic scheme which conceptualizes the naturalization/invasion process. Introduction means that the plant (or its propagule) has been transported by humans across a major geographical barrier. Naturalization starts when abiotic and biotic barriers to survival are surmounted and when various barriers to regular reproduction are overcome. Invasion further requires that introduced plants produce reproductive offspring in areas distant from sites of introduction (approximate scales: > 100 m over < 50 years for taxa spreading by seeds and other propagules; > 6 m/3 years for taxa spreading by roots, rhizomes, stolons or creeping stems). Taxa that can cope with the abiotic environment and biota in the general area may invade disturbed, seminatural communities. Invasion of successionally mature, undisturbed communities usually requires that the alien taxon overcomes a different category of barriers.
We propose that the term 'invasive' should be used without any inference to environmental or economic impact. Terms like 'pests' and 'weeds' are suitable labels for the 50–80% of invaders that have harmful effects. About 10% of invasive plants that change the character, condition, form, or nature of ecosystems over substantial areas may be termed 'transformers'. 相似文献
80.
The ITS sequences of Acropora spp. are the shortest so far identified in
any metazoan and are among the shortest seen in eukaryotes; ITS1 was 70-80
bases, and ITS2 was 100-112 bases. The ITS sequences were also highly
variable, but base composition and secondary structure prediction indicate
that divergent sequence variants are unlikely to be pseudogenes. The
pattern of variation was unusual in several other respects: (1) two
distinct ITS2 types were detected in both A. hyacinthus and A. cytherea,
species known to hybridize in vitro with high success rates, and a putative
intermediate ITS2 form was also detected in A. cytherea; (2) A. valida was
found to contain highly (29%) diverged ITS1 variants; and (3) A.
longicyathus contained two distinct 5.8S rDNA types. These data are
consistent with a reticulate evolutionary history for the genus Acropora.
相似文献