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排序方式: 共有141条查询结果,搜索用时 15 毫秒
51.
A genome survey of Moniliophthora perniciosa gives new insights into Witches' Broom Disease of cacao
Jorge MC Mondego Marcelo F Carazzolle Gustavo GL Costa Eduardo F Formighieri Lucas P Parizzi Johana Rincones Carolina Cotomacci Dirce M Carraro Anderson F Cunha Helaine Carrer Ramon O Vidal Raíssa C Estrela Odalys García Daniela PT Thomazella Bruno V de Oliveira Acássia BL Pires Carolina S Maria Rio Marcos Renato R Araújo Marcos H de Moraes Luis AB Castro Karina P Gramacho Marilda S Gonçalves José P Moura Neto Aristóteles Góes Neto Luciana V Barbosa Mark J Guiltinan Bryan A Bailey Lyndel W Meinhardt Julio CM Cascardo Gonçalo AG Pereira 《BMC genomics》2008,9(1):1-25
52.
We compared histochemical and immunohistochemical staining as well as fluorochrome labeling in murine bone specimens that were fixed with 10% neutral buffered formalin to those fixed with HistoChoice®. We showed that sections from undecalcified tibiae fixed for 4 h in HistoChoice® resulted in enhanced toluidine blue and Von Kossa histochemical staining compared to formalin fixation. HistoChoice® produced comparable or improved staining for alkaline phosphatase. Acid phosphatase localization was better in formalin fixed specimens, but osteoclasts were visuralized more easily in HistoChoice® fixed specimens. As expected, immunohistochemical labeling was antibody dependent; some antibodies labeled better in HistoChoice® fixed specimens while others were better in formalin fixed specimens. Toluidine blue, Von Kossa, and alkaline phosphatase staining of sections fixed for 12 h produced sections that were similar to 4 h fixed sections. Fixation for 12 h preserved acid phosphatase activity better. Increasing fixation to 12 h affected immunolocalization differentially. Bone sialoprotein labeling in HistoChoice® fixed specimens was comparable to formalin fixed samples. On the other hand, after 12 h formalin fixation, osteocalcin labeling was comparable to HistoChoice®. For most histochemical applications, fixing murine bone specimens for 4 h with HistoChoice® yielded superior staining compared to formalin fixation. If immunohistochemical localization is desired, however, individual antibodies must be tested to determine which fixation process retains antigenicity better. In addition, there was no detectable difference in the intensity of fluorochrome labeling using either fixative. Finally, fixation duration did not alter the intensity of labeling. 相似文献
53.
JP Herv s J. Martí -Clú a A. Mu oz-Garcí a MC Santa-Cruz 《Biotechnic & histochemistry》2002,77(1):27-35
We have optimised an indirect immunoperoxidase technique demonstrating bromodeoxyuridine (BrdU) incorporation into dividing cells for cerebellar tissue sections of four-day-old rats injected with this marker. This permits confident identification of granule-cell precursors engaged in DNA synthesis in the external granular layer of the developing cerebellum. Preservation of BrdU immunoreactivity is attained using methanol/acetic acid fixation and different pretreatments before immunostaining, while unlabeled nuclei can be recognized clearly after Feulgen or hematoxylin counterstaining. We established conditions to ensure satisfactory BrdU uptake without affecting cell-cycle progression during the postlabeling time period. The dose of BrdU employed provides saturation S-phase labeling from at least 1 h after BrdU delivery. Various kinetic parameters and phase durations have been determined in experiments involving a single injection or cumulative labeling sequences, and the cycle time was calculated based on two models of generative behavior: steady-state and exponential growth. The working hypothesis of steadystate kinetics can be adopted successfully if the existence of neuroblasts with different proliferation rates is taken into account. 相似文献
54.
M M French S E Smith K Akanbi T Sanford J Hecht M C Farach-Carson D D Carson 《The Journal of cell biology》1999,145(5):1103-1115
Expression of the basement membrane heparan sulfate proteoglycan (HSPG), perlecan (Pln), mRNA, and protein has been examined during murine development. Both Pln mRNA and protein are highly expressed in cartilaginous regions of developing mouse embryos, but not in areas of membranous bone formation. Initially detected at low levels in precartilaginous areas of d 12.5 embryos, Pln protein accumulates in these regions through d 15.5 at which time high levels are detected in the cartilage primordia. Laminin and collagen type IV, other basal lamina proteins commonly found colocalized with Pln, are absent from the cartilage primordia. Accumulation of Pln mRNA, detected by in situ hybridization, was increased in d 14.5 embryos. Cartilage primordia expression decreased to levels similar to that of the surrounding tissue at d 15.5. Pln accumulation in developing cartilage is preceded by that of collagen type II. To gain insight into Pln function in chondrogenesis, an assay was developed to assess the potential inductive activity of Pln using multipotential 10T1/2 murine embryonic fibroblast cells. Culture on Pln, but not on a variety of other matrices, stimulated extensive formation of dense nodules reminiscent of embryonic cartilaginous condensations. These nodules stained intensely with Alcian blue and collagen type II antibodies. mRNA encoding chondrocyte markers including collagen type II, aggrecan, and Pln was elevated in 10T1/2 cells cultured on Pln. Human chondrocytes that otherwise rapidly dedifferentiate during in vitro culture also formed nodules and expressed high levels of chondrocytic marker proteins when cultured on Pln. Collectively, these studies demonstrate that Pln is not only a marker of chondrogenesis, but also strongly potentiates chondrogenic differentiation in vitro. 相似文献
55.
56.
Hecht JT Hayes E Haynes R Cole WG Long RJ Farach-Carson MC Carson DD 《Differentiation; research in biological diversity》2005,73(5):212-221
An exostosis or osteochondroma is an aberrant bony growth occurring next to the growth plate either as an isolated growth abnormality or as part of the Hereditary Multiple Exostosis (HME) syndrome. Mutations in either exostosin 1 (EXT1) or exostosin 2 (EXT2) gene cause the HME syndrome and also some isolated osteochondromas. The EXT1 and EXT2 genes are glycosyltransferases that function as hetero-oligomers in the Golgi to add repeating glycosaminoglycans (GAGs) to heparan sulfate (HS) chains. Previously, we demonstrated that HS is markedly diminished in the exostosis cartilage cap and that the HS proteoglycan, perlecan, has an abnormal distribution in these caps. The present studies were undertaken to evaluate which chondrocyte-specific functions are associated with diminished HS synthesis in human chondrocytes harboring either EXT1 or EXT2 mutations. Systematic evaluation of exostosis cartilage caps and chondrocytes, both in vitro and in vivo, suggests that chondrocyte-specific cell functions account for diminished HS levels. In addition, we provide evidence that perichondrial cells give rise to chondrocytes that clonally expand and develop into an exostosis. Undifferentiated EXT chondrocytes synthesized amounts of HS similar to control chondrocytes; however, EXT chondrocytes displayed very poor survival in vitro under conditions that promote normal chondrocyte differentiation with high efficiency. Collectively, these observations suggest that loss of one copy of either the EXT1 or EXT2 gene product compromises the perichondrial chondrocytes' ability to differentiate normally and to survive in a differentiated state in vitro. In vivo, these compromised responses may lead to abnormal chondrocyte growth, perhaps from a perichondrial stem cell reserve. 相似文献
57.
We studied the effect of extracellular Ca2+ concentration ([Ca2+]e) on adipocyte differentiation. Preadipocytes exposed to continuous [Ca2+]e higher than 2.5 mmol/l accumulated little or no cytoplasmic lipid compared to controls in 1.8 mmol/l [Ca2+]e. Differentiation was monitored by Oil Red O staining of cytoplasmic lipid and triglyceride assay of accumulated lipid, by RT-PCR analysis of adipogenic markers, and by the activity of glycerol-3-phosphate dehydrogenase (GPDH). Elevated [Ca2+]e inhibited expression of peroxisome proliferator-activated receptor γ, CCAAT/enhancer binding protein α, and steroid regulatory binding element protein. High [Ca2+]e significantly inhibited differentiation marker expression including adipocyte fatty acid binding protein, and GPDH. The decrease in Pref-1 expression that accompanied differentiation also was prevented by high [Ca2+]e. Treatment of 3T3-L1 cells with high [Ca2+]e did not significantly affect cell number or viability and did not trigger apoptosis. Levels of intracellular Ca+2 remained unchanged in various [Ca2+]e. Treatment of 3T3-L1 with pertussis toxin (PTX) partially restored lipid accumulation and increased differentiation markers in cells treated with 5 mmol/l [Ca2+]e. ‘Classical’ parathyroid cell Ca2+ sensing receptors (CaSR) were not detected either by RT-PCR or by Western blotting. These results suggest that continuos exposure to high [Ca2+]e inhibits preadipocyte differentiation and that this may involve a G-protein-coupled mechanism mediated by a novel Ca2+ sensor or receptor. 相似文献
58.
The respiratory sensation and some routine cardiorespiratory parameters were studied on native Highlanders from the Argentine
Andes and on Lowlanders from Europe, already tested during previous high altitude expeditions. The tests were performed at
various altitude levels from 2688m e.i., the village altitude for Highlanders, to 5600m during an expedition to Mt. Aconcagua
(6990m). At rest, the perception of 4 external inspiratory resistive loads (ranged between 2.5 and 13 cm.H2O.L-1.s) can allow
us to fix by discrimination the sensitivity index P(A) independently of response bias (B) according to Sensory Decision Theory
(SDT). The Andean highlanders did not experience the respiratory sensation at the same limits as the European lowlanders well
adaptated to high altitude. At higher altitudes than their village altitude, their respiratory sensation presented a lower
threshold of perception and a weaker discrimination which might be partly explained by the evolution of some parameters of
their cardio-respiratory function when altitude increased. Indeed, in response to high altitude hypoxia (5600m), they increased
their respiratory frequency and not their minuteventilation or mouth pressure. This chosen ventilatory pattern was opposite
to the one chosen by the Lowlanders and did not allow for sufficient adaptation to a more important altitude hypoxia than
that of their village altitude. In conclusion, the Andean highlanders wellbeing adapted to their village altitude, exhibited
a difficult acclimatization to higher altitudes which might be due to the characteristics of their respiratory sensation.
These results might explain their weak physical performances during ascent to the Mt. Aconcagua summit in spite of special
training. 相似文献
59.
Variant forms of a group I intron in nuclear small-subunit rRNA genes of the marine red alga Porphyra spiralis var. amplifolia 总被引:3,自引:0,他引:3
A group IC1 intron occurs in nuclear small-subunit (18S) ribosomal RNA (SSU
rRNA) genes of the marine red alga Porphyra spiralis var. amplifolia. This
intron occurs at the same position as the self- splicing group IC1 introns
in nuclear SSU rDNAs of the fungus Pneumocystis carinii and in the green
alga Chlorella ellipsoidea and shares sequence identity with the
Pneumocystis carinii intron in domains L1, P1, P2, and L2, outside the
conserved core. Three size variants, differing in amount of sequence in L1,
exist and are differentially distributed in geographically distinct
populations. Preliminary data suggest that the largest variant can
self-splice in vitro. Short open reading frames are present but do not
correspond to known genes. Repeated nucleotide motifs, reminiscent of
duplicated target sites of transposons or Alu elements, are associated with
the intron and with one of the variant forms of L1. Insertions are present
in nuclear SSU rDNAs of several other Porphyra species and of the red alga
Bangia atropurpurea; insertionless rDNA variants also occur in several
Porphyra species. Our observations are most readily explained by intron
mobility, although it remains unclear how transfer could have been mediated
between genomes of organisms as ecologically diverse as marine red algae,
freshwater green algae, and a mammalian-pathogenic fungus.
相似文献