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   279篇
  免费   28篇
  2023年   1篇
  2022年   5篇
  2021年   15篇
  2020年   3篇
  2019年   4篇
  2018年   5篇
  2017年   7篇
  2016年   16篇
  2015年   14篇
  2014年   21篇
  2013年   16篇
  2012年   21篇
  2011年   31篇
  2010年   11篇
  2009年   9篇
  2008年   12篇
  2007年   10篇
  2006年   10篇
  2005年   9篇
  2004年   9篇
  2003年   10篇
  2002年   13篇
  2001年   7篇
  2000年   3篇
  1999年   3篇
  1998年   5篇
  1997年   1篇
  1994年   3篇
  1993年   2篇
  1992年   3篇
  1990年   1篇
  1989年   2篇
  1988年   3篇
  1987年   2篇
  1986年   2篇
  1985年   2篇
  1984年   4篇
  1983年   2篇
  1982年   2篇
  1979年   1篇
  1977年   1篇
  1974年   2篇
  1971年   1篇
  1970年   1篇
  1968年   1篇
  1924年   1篇
排序方式: 共有307条查询结果,搜索用时 15 毫秒
1.
2.
Phadiatop is a new in vitro screening test for respiratory allergy. This test, based on the RAST procedure, detects in serum, the presence of specific IgE to a mixture of common inhalent allergens. Among 70 patients (26 children and 44 adults) consulting for respiratory syndrome, Phadiatop was positive in 31 cases. There were a good correlation between this new test and skin tests (59% for adults and 92% for children), total IgE (70% for adults and 65% for children) and RAST (93% for adults and 96% for children). Phadiatop, with a specificity of 100%, a sensitivity of 82% (76% for adults and 92% for children) and an efficiency of 90% (86% for adults and 96% for children), is a more accurate test than total IgE and could be an excellent in vitro screening test for respiratory allergy.  相似文献   
3.
Serum beta 2 microglobulin levels, measured by radioimmunoassay (Phadebas test), were found increased in acute myeloid leukemias at diagnosis. Serum beta 2 microglobulin levels were significantly higher in patients with monocytic leukemias (13 patients, M4-M5 FAB classification) than in those with other cytological types (18 patients). Beta 2 microglobulin levels at diagnosis were correlated with serum lysozyme levels, but they were not correlated with blood blast counts, serum LDH and ferritin levels. 195 serum beta 2 microglobulin measurements were made serially in 30 patients with acute myeloid leukemias in first remission. Compared to values at diagnosis, beta 2 microglobulin levels in remission were significantly decreased. Out of 30 patients in remission 12 had increased serum beta 2 microglobulin levels (greater than 3 mg/l). Serial measurements were not predictive for relapses.  相似文献   
4.
Epithelial cells of the lung are the primary targets for respiratory viruses. Virus-carried single-stranded RNA (ssRNA) can activate Toll-like receptors (TLRs) 7 and 8, whereas dsRNA is bound by TLR3 and a cytoplasmic RNA helicase, retinoic acid-inducible protein I (RIG-I). This recognition leads to the activation of host cell cytokine gene expression. Here we have studied the regulation of influenza A and Sendai virus-induced alpha interferon (IFN-alpha), IFN-beta, interleukin-28 (IL-28), and IL-29 gene expression in human lung A549 epithelial cells. Sendai virus infection readily activated the expression of the IFN-alpha, IFN-beta, IL-28, and IL-29 genes, whereas influenza A virus-induced activation of these genes was mainly dependent on pretreatment of A549 cells with IFN-alpha or tumor necrosis factor alpha (TNF-alpha). IFN-alpha and TNF-alpha induced the expression of the RIG-I, TLR3, MyD88, TRIF, and IRF7 genes, whereas no detectable TLR7 and TLR8 was seen in A549 cells. TNF-alpha also strongly enhanced IKK epsilon mRNA and protein expression. Ectopic expression of a constitutively active form of RIG-I (deltaRIG-I) or IKK epsilon, but not that of TLR3, enhanced the expression of the IFN-beta, IL-28, and IL-29 genes. Furthermore, a dominant-negative form of RIG-I inhibited influenza A virus-induced IFN-beta promoter activity in TNF-alpha-pretreated cells. In conclusion, IFN-alpha and TNF-alpha enhanced the expression of the components of TLR and RIG-I signaling pathways, but RIG-I was identified as the central regulator of influenza A virus-induced expression of antiviral cytokines in human lung epithelial cells.  相似文献   
5.
While several studies have established a positive correlation between community diversity and invasion resistance, it is less clear how species interactions within resident communities shape this process. Here, we experimentally tested how antagonistic and facilitative pairwise interactions within resident model microbial communities predict invasion by the plant–pathogenic bacterium Ralstonia solanacearum. We found that facilitative resident community interactions promoted and antagonistic interactions suppressed invasions both in the lab and in the tomato plant rhizosphere. Crucially, pairwise interactions reliably explained observed invasion outcomes also in multispecies communities, and mechanistically, this was linked to direct inhibition of the invader by antagonistic communities (antibiosis), and to a lesser degree by resource competition between members of the resident community and the invader. Together, our findings suggest that the type and strength of pairwise interactions can reliably predict the outcome of invasions in more complex multispecies communities.  相似文献   
6.
We describe a sensitive liquid phase radioimmunoassay for serum IgD. Extreme values obtained from 85 control patients sera are 0.2 and 121 mg/l with an arithmetic mean of 25 mg/l. In atopic patients (with high serum IgE levels), arithmetic mean is 47 mg/l.  相似文献   
7.
8.
The study area is an urban forest remnant in the city of Tampere (Finland). The presence of vascular plant species were surveyed in 1980 and again in 2000 within the 5 × 5 m grid cells covering the whole forest. The forest fragment has been influenced by three types of urban pressure: general ecological conditions (such as eutrophication due to increase of nitrogen), edge effect and local human disturbance. A general and spatially even eutrophication was reflected in the frequencies of C- and S-strategists as a shift towards to the C-point in the CSR triangle. The total number of native species (83 in 1980, 89 in 2000), typical Vaccinium type (VT)-forest species (32 in 1980, 31 in 2000) and aliens (57 in 1980, 68 in 2000) did change, but only to a moderate extent. The number of typical VT-forest species and native species were more common in central parts of the fragment. In terms of the number of species, the forest has been relatively resistant to date to major changes. However, the average number of native plant species per grid cell increased from 13.7 to 14.4, the average number of aliens increased from 2.0 to 4.2 and the average number of typical VT-forest species decreased from 5.5 to 5.0. Natives were spatially concentrated in the centre in 1980, but in 2000 they were more evenly distributed. The edge has offered habitats for new species, but the typical VT-forest species of the original sub-xeric forest are slowly diminishing.  相似文献   
9.
Isolates from gardening waste compost and 38 culture collection microbes were grown on agar plates at pH 4.0 with the cutinase model substrate polycaprolactone as a carbon source. The strains showing polycaprolactone hydrolysis were cultivated in liquid at acidic pH and the cultivations were monitored by assaying the p-nitrophenyl butyrate esterase activities. Culture supernatants of four strains were analyzed for the hydrolysis of tritiated apple cutin at different pHs. Highest amounts of radioactive hydrolysis products were detected at pHs below 5. The hydrolysis of apple cutin by the culture supernatants at acidic pH was further confirmed by GC–MS analysis of the hydrolysis products. On the basis of screening, the acidic cutinase from Aspergillus niger CBS 513.88 was chosen for heterogeneous production in Pichia pastoris and for analysis of the effects of pH on activity and stability. The recombinant enzyme showed activity over a broad range of pHs with maximal activity between pH 5.0 and 6.5. Activity could be detected still at pH 3.5.  相似文献   
10.
Cytomegalovirus (CMV) is the most common cause of congenital infection, and is a major cause of sensorineural hearing loss and neurological disabilities. Evaluating the risk for a CMV infected fetus to develop severe clinical symptoms after birth is crucial to provide appropriate guidance to pregnant women who might have to consider termination of pregnancy or experimental prenatal medical therapies. However, establishing the prognosis before birth remains a challenge. This evaluation is currently based upon fetal imaging and fetal biological parameters, but the positive and negative predictive values of these parameters are not optimal, leaving room for the development of new prognostic factors. Here, we compared the amniotic fluid peptidome between asymptomatic fetuses who were born as asymptomatic neonates and symptomatic fetuses who were either terminated in view of severe cerebral lesions or born as severely symptomatic neonates. This comparison allowed us to identify a 34-peptide classifier in a discovery cohort of 13 symptomatic and 13 asymptomatic neonates. This classifier further yielded 89% sensitivity, 75% specificity and an area under the curve of 0.90 to segregate 9 severely symptomatic from 12 asymptomatic neonates in a validation cohort, showing an overall better performance than that of classical fetal laboratory parameters. Pathway analysis of the 34 peptides underlined the role of viral entry in fetuses with severe brain disease as well as the potential importance of both beta-2-microglobulin and adiponectin to protect the injured fetal brain infected with CMV. The results also suggested the mechanistic implication of the T calcium channel alpha-1G (CACNA1G) protein in the development of seizures in severely CMV infected children. These results open a new field for potential therapeutic options. In conclusion, this study demonstrates that amniotic fluid peptidome analysis can effectively predict the severity of congenital CMV infection. This peptidomic classifier may therefore be used in clinical settings during pregnancy to improve prenatal counseling.  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