首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   38篇
  完全免费   1篇
  2016年   2篇
  2012年   1篇
  2009年   1篇
  2008年   2篇
  2007年   2篇
  2006年   1篇
  2005年   2篇
  2004年   1篇
  2003年   2篇
  2002年   1篇
  1998年   1篇
  1996年   1篇
  1994年   2篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1984年   3篇
  1981年   1篇
  1978年   2篇
  1976年   2篇
  1974年   2篇
  1973年   1篇
  1971年   1篇
  1965年   1篇
排序方式: 共有39条查询结果,搜索用时 78 毫秒
1.
The success of stem cell transplantation depends on the ability of i.v. infused stem cells to engraft the bone marrow, a process referred to as homing. Efficient homing requires migration of CD34(+) cells across the bone marrow endothelium, most likely through the intercellular junctions. In this study, we show that loss of vascular endothelial (VE)-cadherin-mediated endothelial cell-cell adhesion increases the permeability of monolayers of human bone marrow endothelial cells (HBMECs) and stimulates the transendothelial migration of CD34(+) cells in response to stromal cell-derived factor-1alpha. Stromal cell-derived factor-1alpha-induced migration was dependent on VCAM-1 and ICAM-1, even in the absence of VE-cadherin function. Cross-linking of ICAM-1 to mimic the leukocyte-endothelium interaction induced actin stress fiber formation but did not induce loss of endothelial integrity, whereas cross-linking of VCAM-1 increased the HBMEC permeability and induced gaps in the monolayer. In addition, VCAM-1-mediated gap formation in HBMEC was accompanied by and dependent on the production of reactive oxygen species. These data suggest that modulation of VE-cadherin function directly affects the efficiency of transendothelial migration of CD34(+) cells and that activation of ICAM-1 and, in particular, VCAM-1 plays an important role in this process through reorganization of the endothelial actin cytoskeleton and by modulating the integrity of the bone marrow endothelium through the production of reactive oxygen species.  相似文献
2.
Pancytopenia, hepatosplenomegaly and skeletal complications are hallmarks of Gaucher disease. Monitoring of the outcome of therapy on skeletal status of Gaucher patients is problematic since currently available imaging techniques are expensive and not widely accessible. The availability of a blood test that relates to skeletal manifestations would be very valuable. We here report that macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, both implicated in skeletal complications in multiple myeloma (MM), are significantly elevated in plasma of Gaucher patients. Plasma MIP-1alpha of patients (median 78 pg/ml, range 21-550 pg/ml, n=48) is elevated (normal median 9 pg/ml, range 0-208 pg/ml, n=39). Plasma MIP-1beta of patients (median 201 pg/ml, range 59-647 pg/ml, n=49) is even more pronouncedly increased (normal median 17 pg/ml, range 1-41 pg/ml, n=39; one outlier: 122 pg/ml). The increase in plasma MIP-1beta levels of Gaucher patients is associated with skeletal disease. The plasma levels of both chemokines decrease upon effective therapy. Lack of reduction of plasma MIP-1beta below 85 pg/ml during 5 years of therapy was observed in patients with ongoing skeletal disease. In conclusion, MIP-1alpha and MIP-1beta are elevated in plasma of Gaucher patients and remaining high levels of MIP-1beta during therapy seem associated with ongoing skeletal disease.  相似文献
3.
Rho-like GTPases control a wide range of cellular functions such as integrin- and cadherin-mediated adhesion, cell motility, and gene expression. The hypervariable C-terminal domain of these GTPases has been implicated in membrane association and effector binding. We found that cell-permeable peptides, encoding the C termini of Rac1, Rac2, RhoA, and Cdc42, interfere with GTPase signaling in a specific fashion in a variety of cellular models. Pull-down assays showed that the C terminus of Rac1 does not associate to either RhoGDI or to Pak. In contrast, the C terminus of Rac1 (but not Rac2 or Cdc42) binds to phosphatidylinositol 4,5-phosphate kinase (PIP5K) via amino acids 185-187 (RKR). Moreover, Rac1 associates to the adapter protein Crk via the N-terminal Src homology 3 (SH3) domain of Crk and the proline-rich stretch in the Rac1 C terminus. These differential interactions mediate Rac1 localization, as well as Rac1 signaling, toward membrane ruffling, cell-cell adhesion, and migration. These data show that the C-terminal, hypervariable domain of Rac1 encodes two distinct binding motifs for signaling proteins and regulates intracellular targeting and differential signaling in a unique and non-redundant fashion.  相似文献
4.
SUMMARY. 1. The small Lake Negenmad, in the nature reserve 'De Oude Venen', was isolated from the canals and lakes of the Frisian lake system. Its chemistry and phytoplankton were monitored 1 year before (1984) and 2 years after (1985–86) isolation. These characteristics were compared with those of the adjacent Lake Veertigmad which was not manipulated.
2. The hydrological intervention prevented the inflow of chloride-rich IJsselmeer water into Lake Negenmad and made its water table more dependent on evapotranspiration, precipitation and upwelling water. In comparison with the unmanipulated lake. Lake Negenmad became less saline (c. 50%), more humic (c. 50%) and total dissolved (<0.2,μm) iron concentration increased dramatically.
3. During the 2 years of damming no marked differences in the total nutrient concentrations of either lake were observed. However, the maximum phytoplankton density in the dammed lake was half that in the unmanipulated lake. The lower density may have been caused by low P availability after formation of humus-iron phosphate species.
4. Preventing the inflow of water from the Frisian lake system favoured the occurrence in Lake Negenmad of flagellated species (Chrysophyceae, Cryptophyceae) at the expense of filamentous and nuisance-causing cyanobacteria (Oscillutoria, Anabaena, Aphanizomenon spp.).
5. The implications of these results for water quality management of reservoirs in peaty areas are briefly discussed.  相似文献
5.
6.
7.
We describe ER-HR3, a monoclonal antibody directed against bone marrow-derived haemopoietic reticulum cells. ER-HR3-positive cells have the electronmicroscopic and enzyme-histochemical characteristics of macrophages. Additionally, they are able to phagocytoze. The ER-HR3 antigen is expressed by a majority of blood monocytes and is present on a subpopulation of resident macrophages in multiple organs. ER-HR3-positive cells are abundant in the bone marrow, the splenic red pulp, the mesenteric lymphoid paracortex and the interfollicular areas of the Peyer's patch. Few ER-HR3-positive cells have been observed in the thymic cortex and the connective tissues of the gastro-intestinal tract, the dermis and the renal medulla. Moreover, epidermal Langerhans cells express the antigen. No cross-reactivity with other cell types has been found. It is concluded that ER-HR3 has a unique distribution pattern distinct from other macrophage-specific antibodies.  相似文献
8.
The number of colony forming unit-endothelial cells (CFU-EC) in human peripheral blood was found to be a biological marker for several vascular diseases. In this study, the heterogeneous composition of immune cells in the CFU-ECs was investigated. We confirmed that monocytes are essential for the formation of CFU-ECs. Also, however, CD4(+) T cells were found to be indispensable for the induction of CFU-EC colonies, mainly through cell-cell contact. By blocking or activating CD3 receptors on CD4(+) T cells or blocking MHC class II molecules on monocytes, it was shown that TCR-MHCII interactions are required for induction of CFU-EC colonies. Because the supernatant from preactivated T cells could also induce colony formation from purified monocytes, the T cell support turned out to be cytokine mediated. Gene expression analysis of the endothelial-like colonies formed by CD14(+) cells showed that colony formation is a proangiogenic differentiation and might reflect the ability of monocytes to facilitate vascularization. This in vitro study is the first to reveal the role of TCR-MHC class II interactions between T cells and monocytes and the subsequent inflammatory response as stimulus of monocytic properties that are associated with vascularization.  相似文献
9.
Summary In this study, a simple single-step fixation method for frozen tissue sections is introduced using the hexazotized salt of Pararosaniline as preservative agent. Tissue preservation by this method was shown to be superior to the commonly-used fixation with acetone. Fixation with hexazotized Pararosaniline caused a minimal loss of antigenicity as demonstrated using twenty-three monoclonal antibodies directed against lympho-haemopoietic and stromal cells.  相似文献
10.
The sex pheromone of the potato tuberworm moth,Phthorimaea operculella (Zell.) has been identified as a mixture oftrans-4,cis-7-tridecadienyl acetate andtrans-4,cis-7,cis-10 tridecatrienyl acetate. The identifications have been carried out by means of electroantennography, mass, infrared and n.m.r. spectroscopy. The identifications have been confirmed by synthesis. Both compounds occur in the insects in about equal amounts.The individual compounds are attractive to male moths in pheromone traps. The triolefinic ester was found to be much more attractive than the diolefinic ester.However, mixtures of both compounds in the ranges of 4:1 to 1:4 are much more attractive than the individual compounds or traps baited with two virgin female moths.
Zusammenfassung Das Sexualpheromon vonPhthorimaea operculella (Gelechiidae) wurde identifiziert als ein Gemisch vontrans-4,cis-7-Tridecadienylacetat undtrans-4,cis-7,cis-10-Tridecatrienylacetat. Die beiden Identifizierungen wurden durchgeführt mit Hilfe von Elektroantennografie, Massenspektroskopie, Ultrarotspektroskopie und Kernspinnresonanzspektroskopie.Die beiden Identifizierungen wurden durch Synthese bestätigt. Die Pheromonkomponenten wurden in etwa gleiche Mengen von den Faltern isoliert. Beide Substanzen erwiesen sich sowohl in natürlicher wie in synthetischer Form als aktiv in der Elektroantennografie sowie im biologischen Test und in Sexfallen.Ein Mischungsverhältnis der beiden Komponenten von 4 : 1 bis 1 : 4 weist eine viel höhere Lockstoffwirkung auf als die beiden Einzelkomponenten oder als zwei lebende Weibchen.Ein Isomer des natürlichen Tridecatrienylacetat, nämlichcis-4,trans-7,cis-10-Tridecatrienylacetate, war nur schwach aktiv in den verschiedenen Testen. In Sexfallen wurde die Aktivität dieses Isomers durch Zusatz vontrans-4,cis-7-Tridecadienylacetat nicht erhöht.
  相似文献
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号