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   82篇
  免费   5篇
  2016年   2篇
  2015年   4篇
  2014年   4篇
  2013年   8篇
  2012年   11篇
  2011年   8篇
  2010年   4篇
  2009年   2篇
  2008年   1篇
  2007年   4篇
  2006年   5篇
  2005年   3篇
  2004年   4篇
  2003年   1篇
  2002年   3篇
  2001年   1篇
  2000年   2篇
  1997年   2篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1989年   1篇
  1988年   2篇
  1987年   1篇
  1985年   2篇
  1984年   2篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
排序方式: 共有87条查询结果,搜索用时 850 毫秒
1.
Investigations were conducted to quantify activity of uteroglobin mRNA and secretion of uteroglobin in rabbit uterus after administration of progesterone and 5alpha-dihydrotestosterone, either alone or concomitantly with oestradiol-17beta and tamoxifen, a non-steroidal anti-oestrogen. Poly(A)-containing mRNA was isolated from the uterine tissue by extraction with phenol/chloroform, precipitation with ethanol and chromatography on oligo(dT)-cellulose. Cell-free translation in vitro of the poly(A)-containing mRNA was carried out in a wheat-germ lysate, and the product isolated by specific immuno-precipitation with anti-uteroglobin antiserum purified by affinity chromatography. Radioimmunoassay was utilized to determine uteroglobin content in the uterine flushings and tissue preparations. When given for 5 days, both progesterone (1mg/kg per day) and 5alpha-dihydrotestosterone (25mg/kg per day) elicited a marked induction of uteroglobin secretion, which was accompanied with accumulation of uteroglobin mRNA in the tissue. Concomitant administration of oestradiol-17beta (50mug/kg per day) or tamoxifen (12.5mg/kg per day) significantly decreased both progesterone- and 5alpha-dihydrotestosterone-induced uteroglobin secretion, with a parallel decrease in the uteroglobin-mRNA activity. The decline in the uteroglobin content of the uterine flushes brought about by oestradiol-17beta or tamoxifen administration was not due to inhibition of secretion of this protein by the endometrial cells, since a simultaneous decrease occurred in the tissue uteroglobin content. After a 5-day pretreatment with progesterone (1mg/kg per day), administration of oestradiol-17beta (50mug/kg per day) during the ensuing 4 days greatly accelerated the decay of the uteroglobin content in the uterine fluid.  相似文献   
2.
Transrectal or transabdominal examinations of 13 pluriparous reindeer (Rangifer tarandus tarandus) by ultrasonography from the start of mating until week 20 of gestation were conducted to find out when pregnancy could first be detected and to describe fetal development in early pregnancy. The examinations (n=35 per animal) were performed with a 5 MHz linear transducer from 7th October until 1st January and with a 3 MHz sector transducer from that time until 24th February. Time of pregnancy diagnosis by ultrasonography, the first fetal heartbeat and measurements of crown-rump length, chest width and chest depth were recorded during the examinations. Pregnancy was diagnosed by transrectal ultrasonography between the weeks 3 and 7 of gestation. The accuracy of the pregnancy diagnosis, defined as the proportion of females correctly detected to be pregnant, was 15% at week 3, 46% at week 4, 77% at week 5, and 92% at week 6 of gestation. Fetal heartbeat was first detected between the weeks 5 and 8 of gestation. The first measurements of crown-rump length were made on week 3 of gestation, of chest width on week 4 and of chest depth on week 5 of gestation. Chest width and depth were detectable until the end of the study at week 20 of gestation. Transrectal ultrasonography is an efficient tool in early pregnancy diagnosis of reindeer. The fetal growth curves obtained by ultrasonography resembled those obtained in previous morphological studies.  相似文献   
3.

Background

Interleukin-17 (IL-17) acts as a key regulator in central nervous system (CNS) inflammation. γδ T cells are an important innate source of IL-17. Both IL-17+ γδ T cells and microglia, the major resident immune cells of the brain, are involved in various CNS disorders such as multiple sclerosis and stroke. Also, activation of Toll-like receptor (TLR) signaling pathways contributes to CNS damage. However, the mechanisms underlying the regulation and interaction of these cellular and molecular components remain unclear.

Objective

In this study, we investigated the crosstalk between γδ T cells and microglia activated by TLRs in the context of neuronal damage. To this end, co-cultures of IL-17+ γδ T cells, neurons, and microglia were analyzed by immunocytochemistry, flow cytometry, ELISA and multiplex immunoassays.

Results

We report here that IL-17+ γδ T cells but not naïve γδ T cells induce a dose- and time-dependent decrease of neuronal viability in vitro. While direct stimulation of γδ T cells with various TLR ligands did not result in up-regulation of CD69, CD25, or in IL-17 secretion, supernatants of microglia stimulated by ligands specific for TLR2, TLR4, TLR7, or TLR9 induced activation of γδ T cells through IL-1β and IL-23, as indicated by up-regulation of CD69 and CD25 and by secretion of vast amounts of IL-17. This effect was dependent on the TLR adaptor myeloid differentiation primary response gene 88 (MyD88) expressed by both γδ T cells and microglia, but did not require the expression of TLRs by γδ T cells. Similarly to cytokine-primed IL-17+ γδ T cells, IL-17+ γδ T cells induced by supernatants derived from TLR-activated microglia also caused neurotoxicity in vitro. While these neurotoxic effects required stimulation of TLR2, TLR4, or TLR9 in microglia, neuronal injury mediated by bone marrow-derived macrophages did not require TLR signaling. Neurotoxicity mediated by IL-17+ γδ T cells required a direct cell-cell contact between T cells and neurons.

Conclusion

Taken together, these results point to a crucial role for microglia activated through TLRs in polarization of γδ T cells towards neurotoxic IL-17+ γδ T cells.  相似文献   
4.
Ecosystem services are vital for humans in urban regions. However, urban development poses a great risk for the ability of ecosystems to provide these services. In this paper we first address the most important ecosystem services in functional urban regions in Finland. Well accessible and good quality recreational ecosystem services, for example, provided by urban nature, are an important part of a high-quality living environment and important for public health. Vegetation of urban regions can have a role in carbon dioxide sequestration and thus in climate change mitigation. For instance, estimates of carbon sinks can be compared to total CO2 emissions of an urban region, and the municipality can aim at both increasing carbon sinks and decreasing CO2 emissions with proper land-use planning. Large and contiguous core nature areas, smaller green areas and ecological connections between them are the essence of regional ecological networks and are essential for maintaining interconnected habitats for species and thus biological diversity. Thus, both local and regional level ecological networks are vital for maintaining ecosystem services in urban regions. The impacts of climate change coupled with land-use and land cover change will bring serious challenges for maintaining ecosystem services in urban areas. Although not yet widely used in planning practices, the ecosystem services approach can provide an opportunity for land-use planning to develop ecologically sustainable urban regions. Currently, information on ecosystem services of urban regions is lacking and there is a need to improve the knowledge base for land-use planning.  相似文献   
5.
6.
The objective of the present study was to investigate the interactive effects of elevated [CO2] and soil nutrient availability on secondary xylem structure and chemical composition of 41‐year‐old Norway spruce (Picea abies (L.) Karst.) trees. The nonfertilized and irrigated‐fertilized trees were, for 3 years, continuously exposed to elevated [CO2] in whole‐tree chambers. Elevated [CO2] decreased concentrations of soluble sugars, acid‐soluble lignin and nitrogen in stem wood, but the effects were not consistent between sampling height and/or fertilization. The effect of 2*ambient [CO2] on wood structure depended on the exposure year and/or fertilization. Radial lumen diameter decreased and annual ring width increased in the second year of exposure (1999) in elevated [CO2]. In the latter, the CO2 effect was significant only in the nonfertilized trees. Stem wood chemistry and structure were significantly affected by fertilization. Fertilization increased the concentrations of nitrogen and gravimetric lignin, annual ring width, and radial lumen diameter. Fertilization decreased C/N ratio, mean ring density, earlywood density, latewood density, cell wall thickness, cell wall index, and latewood percentage. We conclude that elevated [CO2] had only minor effects on wood properties while fertilization had more marked effects and thus may affect ecosystem processes and suitability of wood for different end‐use purposes.  相似文献   
7.
We studied the effect of long-term nitrogen fertilisation on wood chemistry at two boreal sites in Finland: the northern site (Kemijärvi) and the southern site (Heinola). N-fertilisation was repeated in five-year intervals from the 1960s. Norway spruce (Picea abies L. Karst.) trees that had been planted in 1938 and 1954, in the northern and the southern site, respectively, were harvested in October 2002. Altogether 20 trees, in five different size classes, either unfertilised or fertilised, were felled. Wood sections at breast height, consisting of five consecutive annual rings, from six (Kemijärvi) or five (Heinola) points with different distances from the pith were examined. Differences in growth between the northern and southern sites were marked in favour of the southern site. In the northern site fertilisation had clearly increased the diameter growth, while in the southern site fertilisation had no effect. Nitrogen fertilisation resulted in slight changes in wood chemistry that included increased nitrogen concentrations in the northern site and extractives in the southern site. Stem wood had higher concentrations of extractives, starch, and uronic acids, and lower concentration of cellulose, in the northern than in the southern site. Changes in the stem wood chemistry along radial axis were marked. The changes in wood chemistry are discussed in relation to the physiological function and also how the changes can influence the suitability of wood for different end-use purposes.  相似文献   
8.
The mining industry is a very rapidly increasing production sector in Finland. Many new mines have been opened recently and others are in the planning phase. Mining legislation has been recently revised and compilation of an ID-directive (Industrial Emission Directive, 2010) required to implement environmental law revision is in progress. The aim of this study was to compare different digestion methods recommended by the Finnish Environmental Administration for threshold and guideline value determinations in the Finnish PIMA Decree (214/2007) and Government Decree (591/2006) concerning recovery of certain wastes in earth construction. Altogether six methods were tested, of which five were microwave-assisted acid digestion methods: ISO 11466, EPA Method 3051A (aqua region), EPA Method 3051A (HNO3), EPA Method 3051A (HNO3/HCl), and SFS-EN 13656, while one was a fusion method with lithium tetraborate (ASTM C 1391 - 95). The results showed that concentrations of heavy metals (As, Cd, Co, Cu, Ni, Pb, Sb, V, and Zn) can be determined reproducibly with standard methods, but the chemical method used can have a significant impact on the results. This conclusion is very important, because the measured heavy metal values can affect the classification and processing of waste materials, and thereby can significantly impact the cost of treatment.  相似文献   
9.
Scots pine (Pinus sylvestris L.) seedlings were fumigated with 1.2–1.5 x ambient ozone (cumulative exposure) over 2 seasons in an open-air experiment. Starch and fatty acid concentrations were analyzed in needle and root tissue in the summer, autumn and early winter. Seedling growth was determined by measuring the height of the stem and the total shoot and root biomass. Significant decreases in growth were found in exposed seedlings, even though visible symptoms were lacking. Almost significant reductions in needle and root starch concentrations were found. In the ozone treated foliage, significant increases in myristic acid (140) were detected, but the major fatty acids remained unchanged. Fatty acid ratios showed that the degree of unsaturation decreased in treated needles in the summer. In the roots of ozone treated seedlings, changes in fatty acids were different from those in the foliage. Decreases of the main root fatty acids (160, 180, 181, 18:2, 183) were detected in the summer. These results show that Scots pine is susceptible to enhanced levels of ozone. If the tropospheric ozone levels continue to increase it may have deleterious effects on Scots pine forests in Finland.  相似文献   
10.
M. Fraccaro  J. Lindsten  C. E. Ford  L. Iselius  A. Antonelli  P. Aula  A. Aurias  A. D. Bain  M. Bartsch-Sandhoff  F. Bernardi  E. Boyd  L. F. Buchanan  A. H. Cameron  A. de la Chapelle  G. Ciuffa  C. Cuoco  B. Dutrillaux  G. Dutton  M. A. Ferguson-Smith  D. Francesconi  J. P. M. Geraedts  G. Gimelli  J. Gueguen  E. Gärsner  A. Hagemeijer  F. J. Hansen  P. E. Hollings  T. W. J. Hustinx  A. Kaakinen  J. J. P. van de Kamp  H. von Koskull  J. Lejeune  R. H. Lindenbaum  H. H. McCreanor  M. Mikkelsen  F. Mitelman  B. Nicoletti  J. Nilsby  B. Nilsson  B. Noel  E. Padovani  F. Pasquali  J. de Pater  C. Pedersen  F. Petersen  E. B. Robson  J. Rotman  M. Ryynänen  E. Sachs  J. Salat  R. H. Smythe  I. Stabell  I. Šubrt  P. Vampirelli  G. Wessner  L. Zergollern  O. Zuffardi 《Human genetics》1980,56(1):21-51
Summary Translocation between the long arms of chromosomes 11 and 22 is usually detected in offspring with an unbalanced karyotype following a 3:1 disjunction resulting in partial trisomy. Since by the end of 1976 it was suspected that this translocation might be more frequent than one would deduce from published reports, it was decided to call for a collaborative effort in Europe to collect unpublished cases. In response, 42 cases were collected in Europe, and one case from New Zealand was added. The following countries were represented with the number of cases indicated in parentheses: Czechoslovakia (2), Denmark (4), Finland (3), France (6), Germany (1), Italy (5), The Netherlands (9), Sweden (6), United Kingdom (4), Yugoslavia (2). The wide geographical distribution indicates a multifocal origin of the translocation. Among the unpublished cases, 31 were ascertained as unbalanced carriers [47,XX or XY,+der(22),t(11;22)] and 12 as balanced balanced carriers [46,XX and XY,t(11;22)]. Among the published cases, 10 were ascertained in unbalanced and 3 in balanced carriers. The breakpoints of the translocations indicated by the contributors varied, the most frequently reported being 11q23;22q11 (25 cases), followed by q25;q13 (10 cases). While the first one seems more likely, it was not possible to decide whether the breakpoints were the same in all cases.All 32 probands with unbalanced karyotypes had inherited the translocation, 31 from the mother and only 1 from the father. This ratio became 43:1 when the published cases were added. A segregation analysis revealed that in families ascertained through probands with unbalanced karyotypes there was a ratio of carriers to normal (all karyotyped) 54:55, not a significant difference. The formal maximum (minimum) recurrence risk for this unbalanced translocation was calculated to be 5.6% (2.7%). When the ascertainment was through a balanced proband, the maximum risk was 2.7%. The risk was calculated as 5.7% for female and 4.3% for male carriers. The mean family size was 1.67 for the offspring of female carriers and 0.78 for the offspring of male carriers. This significant difference suggests that heterozygosity for the translocation reduces fertility in males. Indeed, several of the probands with balanced karyotypes were ascertained because of sub- or infertility. Only 2 de novo translocations were found among the 59 probands, and both, were among the 12 cases ascertained as balanced carriers. The source, quality, and quantity of the clinical data for the subjects with unbalanced karyotypes were variable, and no definite conclusions were possible about phenotypes. The following signs were recorded in 10 or more of the 45 cases: low birth weight, delayed psychomotor development, hypotonia, microcephaly, craniofacial asymmetry, malformed ears with pits and tags, cleft palate, micro-/retrognathia, large beaked nose, strabismus, congenital heart disease, cryptorchidism, and congenital dislocation of the hip joints. Many signs were similar to those considered typical of trisomy 11q, and the phenotype coincided almost completely with the presumptive phenotype of complete trisomy 22. No cases with coloboma was recorded, while other signs of the cat-eye syndrome were found in several probands. This might indicate that individuals with the cat-eye syndrome and carriers of the unbalanced 11/22 translocation have the same segment of 22 in triplicate plus or minus another chromosome segment.  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