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   87篇
  免费   7篇
  94篇
  2024年   1篇
  2023年   1篇
  2021年   2篇
  2020年   3篇
  2019年   1篇
  2018年   7篇
  2017年   2篇
  2016年   3篇
  2015年   6篇
  2014年   6篇
  2013年   10篇
  2012年   10篇
  2011年   9篇
  2010年   5篇
  2009年   4篇
  2008年   6篇
  2007年   3篇
  2006年   3篇
  2005年   2篇
  2004年   5篇
  2003年   3篇
  1992年   1篇
  1987年   1篇
排序方式: 共有94条查询结果,搜索用时 15 毫秒
61.
A new species of softnose skate (Arhynchobatidae) is described, based on a single adult male measuring 895 mm TL that was collected at a depth of 953–1,022 m on the Coriolis Bank off western New Caledonia in the southwestern Pacific Ocean. The specimen conforms to the genus Bathyraja in having the rostral cartilage continuous with the neurocranium and very slender and uncalcified over its length. Bathyraja leucomelanos sp. nov. differs from its congeners through a combination of the following characters: distinctive coloration of the disc with white dorsal and black ventral surfaces, dorsal surface of the disc entirely covered with dermal denticles, ventral surface naked, anterior portion of the anterior margin of the disc straight, snout long and very broad with orbit about 6.0 times in preorbital length, orbit 0.73 times interorbital width, mouth 6.8% TL, tail 0.88 times precloacal length, accessory terminal 2 cartilage of the clasper having an expanded disc-shaped tip, and alar thorn tip undulating. Molecular barcoding from the COI sequence reveals that this new species is genetically close to B. spinicauda from the North Atlantic Ocean.  相似文献   
62.
ObjectiveTo describe clinical presentation, preoperative study, intervention, histology, surgical complications and follow-up characteristics, and survival in patients with thyroid carcinoma (TC) with less than 18 years at presentation.Material and methodsretrospective analysis of clinical data of all children and adolescents followed in S. João Hospital from January 1, 2000 to March 31, 2010 with histologic diagnosis of TC.ResultsTwenty-three patients were identified, 19 girls, and 4 boys. Median age at presentation was 17.0 years. Annual incidence was 2.3 cases/year. The main presenting symptom was a solitary thyroid nodule (60.8%). Three (13%) patients had risk factors for TC, 2 of the 3 had previous cervical irradiation. The other was a smoker. Total thyroidectomy was performed in 16 (69.6%), and 10 patients underwent a second surgical procedure. Four (17.4%) patients had postoperative complications. Histologic examination revealed differentiated TC in all, papillary thyroid carcinoma (PTC) in 86.9%, follicular carcinoma in the remaining. All patients received thyroxine suppressive therapy and 20 underwent therapeutic radioactive iodine (131I). During follow-up (7.1 years), 7 out of the 23 patients presented new metastases and needed new treatment. All patients are currently alive.ConclusionsTC is a reality in pediatric population, thyroid routine examination should take part in all clinical examination in children and adolescents.  相似文献   
63.
Gaidropsarus Rafinesque, 1810 is a genus of marine fishes, commonly known as rocklings, comprising 14 living species and showing a high ecological diversity from the intertidal zone to the deep sea. The systematics of this group has been controversial due to a general lack of representative specimens and the conservative morphology exhibited. A multidisciplinary approach combining the analysis of meristic data and the DNA barcode standard was applied in a species delimitation approach. Individuals representing eight valid and three unnamed species were collected, morphologically identified and archived in several museum collections. Comparison of DNA sequences shows complex results, furthering the idea of the difficult identification of specimens based on traditional taxonomy. DNA barcoding supports synonymies, like G. biscayensisG. macrophthalmus and G. guttatusG. mediterraneus, agreeing with the extensive overlaps observed in the meristic variables analysed and suggesting a reduction in the number of species. Genetic distances showed pairs of closely related species like G. grantiG. vulgaris and G. argentatusG. ensis, the latter being only distinguished by one main distinctive character. Four deep-water specimens, morphologically classified only to the genus level, constituted three independent taxa apart from the ones present in this study and with no barcode matches in the repository databases. They could represent new records for the North Atlantic or unknown species of this genus. The results obtained show that more studies will be necessary to solve the systematics of this branch of the Gadiformes.  相似文献   
64.
Five to six hundred millions of people, throughout the world, suffer from malaria and more than one million die each year as a consequence, in about 20% of the cases, of cerebral malaria, an important complication of Plasmodium falciparum infection (Holding & Snow, 2001). Despite many studies, the physiopathology of these cerebral occurrences is not understood, especially concerning the intricacy and respective roles of the various mechanisms identified: sequestration of parasitized red cells in microvessels, cytokine secretion, changes in the T lymphocyte repertoire, host genetic factors driving sensitivity pathogenic factors from Plasmodium (Mazier et al., 2000).  相似文献   
65.
66.

SUMMARY

Fifty years after the discovery of the mouse Mx1 gene, researchers are still trying to understand the molecular details of the antiviral mechanisms mediated by Mx proteins. Mx proteins are evolutionarily conserved dynamin-like large GTPases, and GTPase activity is required for their antiviral activity. The expression of Mx genes is controlled by type I and type III interferons. A phylogenetic analysis revealed that Mx genes are present in almost all vertebrates, usually in one to three copies. Mx proteins are best known for inhibiting negative-stranded RNA viruses, but they also inhibit other virus families. Recent structural analyses provide hints about the antiviral mechanisms of Mx proteins, but it is not known how they can suppress such a wide variety of viruses lacking an obvious common molecular pattern. Perhaps they interact with a (partially) symmetrical invading oligomeric structure, such as a viral ribonucleoprotein complex. Such an interaction may be of a fairly low affinity, in line with the broad target specificity of Mx proteins, yet it would be strong enough to instigate Mx oligomerization and ring assembly. Such a model is compatible with the broad “substrate” specificity of Mx proteins: depending on the size of the invading viral ribonucleoprotein complexes that need to be wrapped, the assembly process would consume the necessary amount of Mx precursor molecules. These Mx ring structures might then act as energy-consuming wrenches to disassemble the viral target structure.  相似文献   
67.
Connectivity between populations influences both their dynamics and the genetic structuring of species. In this study, we explored connectivity patterns of a marine species with long‐distance dispersal, the edible common sea urchin Paracentrotus lividus, focusing mainly on the Adriatic–Ionian basins (Central Mediterranean). We applied a multidisciplinary approach integrating population genomics, based on 1,122 single nucleotide polymorphisms (SNPs) obtained from 2b‐RAD in 275 samples, with Lagrangian simulations performed with a biophysical model of larval dispersal. We detected genetic homogeneity among eight population samples collected in the focal Adriatic–Ionian area, whereas weak but significant differentiation was found with respect to two samples from the Western Mediterranean (France and Tunisia). This result was not affected by the few putative outlier loci identified in our dataset. Lagrangian simulations found a significant potential for larval exchange among the eight Adriatic–Ionian locations, supporting the hypothesis of connectivity of P. lividus populations in this area. A peculiar pattern emerged from the comparison of our results with those obtained from published P. lividus cytochrome b (cytb) sequences, the latter revealing genetic differentiation in the same geographic area despite a smaller sample size and a lower power to detect differences. The comparison with studies conducted using nuclear markers on other species with similar pelagic larval durations in the same Adriatic–Ionian locations indicates species‐specific differences in genetic connectivity patterns and warns against generalizing single‐species results to the entire community of rocky shore habitats.  相似文献   
68.
69.
The cytokine TNF is a well known drug target for several inflammatory diseases such as Crohn disease. Despite the great success of TNF blockers, therapy could be improved because of high costs and side effects. Selective inhibition of TNF receptor (TNFR) 1 signaling holds the potential to greatly reduce the pro-inflammatory activity of TNF, thereby preserving the advantageous immunomodulatory signals mediated by TNFR2. We generated a selective human TNFR1 inhibitor based on Nanobody (Nb) technology. Two anti-human TNFR1 Nbs were linked with an anti-albumin Nb to generate Nb Alb-70-96 named “TNF Receptor-One Silencer” (TROS). TROS selectively binds and inhibits TNF/TNFR1 and lymphotoxin-α/TNFR1 signaling with good affinity and IC50 values, both of which are in the nanomolar range. Surface plasmon resonance analysis reveals that TROS competes with TNF for binding to human TNFR1. In HEK293T cells, TROS strongly reduces TNF-induced gene expression, like IL8 and TNF, in a dose-dependent manner; and in ex vivo cultured colon biopsies of CD patients, TROS inhibits inflammation. Finally, in liver chimeric humanized mice, TROS antagonizes inflammation in a model of acute TNF-induced liver inflammation, reflected in reduced human IL8 expression in liver and reduced IL6 levels in serum. These results demonstrate the considerable potential of TROS and justify the evaluation of TROS in relevant disease animal models of both acute and chronic inflammation and eventually in patients.  相似文献   
70.
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