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31.
B H Tom C M Macek L Raphael J Sengupta E A Cerny M M Jonah Y E Rahman 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1983,172(1):16-28
The purpose of this study was to begin investigating the nature of liposome interactions with colon tumor cells. Thus, experiments were performed to study the uptake and incorporation of multilamellar and of reverse-phase evaporation liposomes of neutral charge into monolayers, suspended spinner cultures, and trypsinized cells of a human colon adenocarcinoma cell line, LS174T. The results showed that the same tumor cells cultured under each condition exhibited a distinct pattern of vesicle uptake as determined at 0, 15, 30, 60, and 120 min. In monolayer cultures of LS174T cells, the uptake of liposomes bearing [3H]actinomycin D in the lipid bilayers was linear throughout the incubation period. In contrast, in trypsinized and spinner suspension cultures, uptake of liposomes was biphasic. There was a proportional uptake of both liposome (labeled with [3H]phosphatidylcholine or [14C]cholesterol) and of actinomycin D (trace labeled with 3H) into the cells under all culture conditions, indicating quantitative delivery of the drug with the intact lipid vesicle. Although the amount of actinomycin D presented to tumor cells by the two liposomes was equivalent, reverse-phase evaporation liposomes were more effective than multilamellar vesicles in inhibiting uridine uptake. In the presence of excess liposomes (10 times the uptake studies), saturation of the tumor cell surface occurred by 120 min. However, the liposomes remained accessible to enzymatic removal for 60 min. Liposome-saturated tumor cells remained refractory to further binding of liposomes for at least 2 hr. The results thus revealed that differences in cell uptake were due to the state of the target cells and not the liposome types, or their differential leakage of labels. 相似文献
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33.
H.-Christian von Büdingen Feng Mei Ariele Greenfield Sarah Jahn Yun-An A. Shen Hugh H. Reid David D. McKemy Jonah R. Chan 《The Journal of cell biology》2015,210(6):891-898
Myelin oligodendrocyte glycoprotein (MOG) is a central nervous system myelin-specific
molecule expressed on the outer lamellae of myelin. To date, the exact function of
MOG has remained unknown, with MOG knockout mice displaying normal myelin
ultrastructure and no apparent specific phenotype. In this paper, we identify nerve
growth factor (NGF) as a binding partner for MOG and demonstrate that this
interaction is capable of sequestering NGF from TrkA-expressing neurons to modulate
axon growth and survival. Deletion of MOG results in aberrant sprouting of
nociceptive neurons in the spinal cord. Binding of NGF to MOG may offer widespread
implications into mechanisms that underlie pain pathways. 相似文献
34.
The number of exponential terms in the function which describes the change in the specific activity of a pool following the
injection of an isotopically labeled tracer is usually considered to equal the number of pools in which the labeled compound
is distributed. However, the number of exponential terms may be smaller than the actual number of pools in the system, even
if all pools exchange material with each other. This study is concerned with the derivation of relationships among the fractional
rates of transfer between pools which are necessary and sufficient for a reduction in the number of exponential terms for
all exchanging pools. The concept of linear dependence among the specific activity functions is basic to this analysis. By
considering these relationships, it is possible to interpret the data on the basis of models consisting of a large number
of pools which satisfy the condition of fast internal mixing. Such models may be necessary for a meaningful interpretation
of tracer data obtained from biological systems. 相似文献
35.
María Delia Basanta Eria A. Rebollar Mirna G. García-Castillo Erica Bree Rosenblum Allison Q. Byrne Jonah Piovia-Scott Gabriela Parra-Olea 《Environmental microbiology》2022,24(1):494-506
Symbiotic bacterial communities are crucial to combating infections and contribute to host health. The amphibian skin microbiome plays an important role in protecting their hosts against pathogens such as Batrachochytrium dendrobatidis (Bd), one of the causative agents of chytridiomycosis, which is responsible for dramatic amphibian population declines worldwide. Although symbiotic skin bacteria are known to inhibit Bd growth, an understanding of the relationship between Bd genetic variability, environmental conditions, and skin bacterial communities is limited. Therefore, we examined the associations between Bd infection load, Bd genetic diversity and skin bacterial communities in five populations of Hyliola regilla (hypochondriaca) from environmentally contrasting sites in Baja California, Mexico. We observed differences in Bd genetics and infection load among sites and environments. Genetic analysis of Bd isolates revealed patterns of spatial structure corresponding to the five sites sampled. Amphibian skin bacterial diversity and community structure differed among environments and sites. Bacterial community composition was correlated with Bd genetic differences and infection load, with specific bacterial taxa enriched on infected and un-infected frogs. Our results indicate that skin-associated bacteria and Bd strains likely interact on the host skin, with consequences for microbial community structure and Bd infection intensity. 相似文献
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Scobie HM Wigelsworth DJ Marlett JM Thomas D Rainey GJ Lacy DB Manchester M Collier RJ Young JA 《PLoS pathogens》2006,2(10):e111
Anthrax toxin receptors 1 and 2 (ANTXR1 and ANTXR2) have a related integrin-like inserted (I) domain which interacts with a metal cation that is coordinated by residue D683 of the protective antigen (PA) subunit of anthrax toxin. The receptor-bound metal ion and PA residue D683 are critical for ANTXR1-PA binding. Since PA can bind to ANTXR2 with reduced affinity in the absence of metal ions, we reasoned that D683 mutant forms of PA might specifically interact with ANTXR2. We show here that this is the case. The differential ability of ANTXR1 and ANTXR2 to bind D683 mutant PA proteins was mapped to nonconserved receptor residues at the binding interface with PA domain 2. Moreover, a D683K mutant form of PA that bound specifically to human and rat ANTXR2 mediated killing of rats by anthrax lethal toxin, providing strong evidence for the physiological importance of ANTXR2 in anthrax disease pathogenesis. 相似文献
38.
The understanding of vertebrate development has advanced considerably in recent years, primarily due to the study of a few model organisms. The zebrafish, the newest of these models, has risen to prominence because both genetic and experimental embryological methods can be easily applied to this animal. The combination of approaches has proven powerful, yielding insights into the formation and function of individual tissues, organ systems and neural networks, and into human disease mechanisms. Here, we provide a personal perspective on the history of zebrafish research, from the assembly of the first genetic and embryological tools through to sequencing of the genome. 相似文献
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The marabou stork (Leptoptilos crumenifer) is widespread and generally abundant in East and Southern Africa, but recent research has found range loss indicative of a population decline in West Africa in recent decades. In the absence of population data, we conducted an in-depth review of the status of the marabou in the region using a plethora of sources together comprising the largest database on the occurrence of the species. Despite caveats and coarseness of the assessment, we estimate the range loss at 52% in West Africa, including extirpation of approximately 64% of known nesting colonies since 2000. The resulting fragmentation has left a metapopulation of likely no more than 100 breeding pairs in The Gambia and Benin and an unknown number of breeders in Cameroon. Knowledge gaps about marabou population ecology in West Africa are significant and prevent an empirical assessment of regional extinction probability. Therefore, we recommend immediate field surveys, especially for breeding colonies, and research into threats and population dynamics. We also recommend the West African metapopulation be listed as regionally critically endangered and that a working group be formed comprising stakeholders from across the region to aid in assessing threats and implementing research and conservation action. 相似文献