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101.
We recently reported that bile salts play a role in the regulation of mucin
secretion by cultured dog gallbladder epithelial cells. In this study we
have examined whether bile salts also influence mucin secretion by the
human epithelial colon cell line LS174T. Solutions of bile salts were
applied to monolayers of LS174T cells. Mucin secretion was quantified by
measuring the secretion of [3H]GlcNAc labeled glycoproteins. Both
unconjugated bile salts as well as taurine conjugated bile salts stimulated
mucin secretion by the colon cells in a dose-dependent fashion. Hydrophobic
bile salts were more potent stimulators than hydrophilic bile salts. Free
(unconjugated) bile salts were more stimulatory compared with their taurine
conjugated counterparts. Stimulation of mucin secretion by LS174T cells was
found to occur at much lower bile salt concentrations than in the
experiments with the dog gallbladder epithelial cells. The protein kinase C
activators PMA and PDB had no stimulatory effect on mucin secretion. We
conclude that mucin secretion by the human colon epithelial cell line
LS174T is regulated by bile salts. We suggest that regulation of mucin
secretion by bile salts might be a common mechanism, by which different
epithelia protect themselves against the detergent action of bile salts, to
which they are exposed throughout the gastrointestinal tract.
相似文献
102.
The endonuclease from Serratia marcescens is a non-specific enzyme that cleaves single and double stranded RNA and DNA. It accepts a phosphorylated pentanucleotide as a minimal substrate which is cleaved in the presence of Mg2+ at the second phosphodiester linkage. The present study is aimed at understanding the role of electrostatic and hydrogen bond interactions in phosphodiester hydrolysis. Towards this objective, six pentadeoxyadenylates with single stereoregular methylphosphonate substitution within this minimal substrate (2a-4b) were synthesized following a protocol described here. These modified oligonucleotides were used as substrates for the Serratia nuclease. The enzyme interaction studies revealed that the enzyme failed to hydrolyze any of the methylphosphonate analogues suggesting the importance of negative charge and/or hydrogen bond acceptors in binding and cleavage of its substrate. Based on these results and available site-directed mutagenesis as well as structural data, a model for nucleic acid binding by Serratia nuclease is proposed. 相似文献
103.
This commentary discusses and summarizes the key highlights of our recently reported work entitled “Neuronal Differentiation of Embryonic Stem Cell Derived Neuronal Progenitors Can Be Regulated by Stretchable Conducting Polymers.” The prospect of controlling the mechanical-rigidity and the surface conductance properties offers a unique combination for tailoring the growth and differentiation of neuronal cells. We emphasize the utility of transparent elastomeric substrates with coatings of electrically conducting polymer to realize the desired substrate-characteristics for cellular development processes. Our study showed that neuronal differentiation from ES cells is highly influenced by the specific substrates on which they are growing. Thus, our results provide a better strategy for regulated neuronal differentiation by using such functional conducting surfaces. 相似文献
104.
Lomon So Sung Su Yea Jean S. Oak Mengrou Lu Arun Manmadhan Qiao Han Ke Matthew R. Janes Linda V. Kessler Jeff M. Kucharski Lian-Sheng Li Michael B. Martin Pingda Ren Katti A. Jessen Yi Liu Christian Rommel David A. Fruman 《The Journal of biological chemistry》2013,288(8):5718-5731
Class IA phosphoinositide 3-kinase (PI3K) is essential for clonal expansion, differentiation, and effector function of B and T lymphocytes. The p110δ catalytic isoform of PI3K is highly expressed in lymphocytes and plays a prominent role in B and T cell responses. Another class IA PI3K catalytic isoform, p110α, is a promising drug target in cancer but little is known about its function in lymphocytes. Here we used highly selective inhibitors to probe the function of p110α in lymphocyte responses in vitro and in vivo. p110α inhibition partially reduced B cell receptor (BCR)-dependent AKT activation and proliferation, and diminished survival supported by the cytokines BAFF and IL-4. Selective p110δ inhibition suppressed B cell responses much more strongly, yet maximal suppression was achieved by targeting multiple PI3K isoforms. In mouse and human T cells, inhibition of single class IA isoforms had little effect on proliferation, whereas pan-class I inhibition did suppress T cell expansion. In mice, selective p110α inhibition using the investigational agent MLN1117 (previously known as INK1117) did not disrupt the marginal zone B cell compartment and did not block T cell-dependent germinal center formation. In contrast, the selective p110δ inhibitor IC87114 strongly suppressed germinal center formation and reduced marginal zone B cell numbers, similar to a pan-class I inhibitor. These findings show that although acute p110α inhibition partially diminishes AKT activation, selective p110α inhibitors are likely to be less immunosuppressive in vivo compared with p110δ or pan-class I inhibitors. 相似文献
105.
Kalpana S. Katti Chunju Gu Dinesh R. Katti 《Biomechanics and modeling in mechanobiology》2016,15(1):155-167
The heterogeneity of bone shape and size variation is modulated by genetic, mechanical, nutritional, and hormonal patterning throughout its lifetime. Microstructural changes across cross sections are a result of mechanistic optimization that results over the years of evolution while being based on universal, time-invariant ingredients and patterns. Here we report changes across anatomical sections of bone with osteogenesis imperfecta (OI) that undermines the work of evolution through genetic mutation. This work examines the microstructure and molecular composition of different anatomical positions (anterior, medial, posterior, and lateral regions) in the diaphysis of an OI human tibia. The study shows that although there is no significant microstructural difference, molecular changes are observed using FTIR revealing differences in molecular composition of the four anatomical positions. In addition, the nanomechanical properties of anterior section of OI bone seem more heterogeneous. The nanomechanical properties of interstitial lamellae in all these bone samples are consistently greater than those of osteonal lamellae. The nanomechanical properties of bone depend on its anatomical section and on the measurement direction as well. Variations in molecular structure with anatomical positions and also corresponding differences in nanomechanical properties are reported. These are compared to those observed typically in healthy bone illustrating the unique influence of OI on bone multiscale behavior which results from an evolutionary process lasting for many years. 相似文献
106.
Samhita S Rhodes Amadou KS Camara Kristina M Ropella Said H Audi Matthias L Riess Paul S Pagel David F Stowe 《Biomedical engineering online》2006,5(1):16-14
Background
The phase-space relationship between simultaneously measured myoplasmic [Ca2+] and isovolumetric left ventricular pressure (LVP) in guinea pig intact hearts is altered by ischemic and inotropic interventions. Our objective was to mathematically model this phase-space relationship between [Ca2+] and LVP with a focus on the changes in cross-bridge kinetics and myofilament Ca2+ sensitivity responsible for alterations in Ca2+-contraction coupling due to inotropic drugs in the presence and absence of ischemia reperfusion (IR) injury. 相似文献107.