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   140篇
  免费   8篇
  2014年   5篇
  2013年   8篇
  2012年   4篇
  2011年   4篇
  2010年   6篇
  2009年   3篇
  2008年   2篇
  2007年   4篇
  2005年   2篇
  2001年   4篇
  2000年   2篇
  1999年   3篇
  1998年   2篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1989年   2篇
  1988年   3篇
  1987年   2篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1977年   2篇
  1958年   1篇
  1951年   4篇
  1945年   1篇
  1943年   1篇
  1929年   1篇
  1928年   1篇
  1927年   2篇
  1925年   2篇
  1922年   1篇
  1921年   1篇
  1920年   2篇
  1917年   2篇
  1916年   1篇
  1915年   1篇
  1914年   2篇
  1912年   3篇
  1911年   7篇
  1910年   2篇
  1909年   4篇
  1908年   5篇
  1907年   3篇
  1906年   4篇
  1905年   3篇
  1903年   1篇
  1902年   1篇
排序方式: 共有148条查询结果,搜索用时 31 毫秒
51.

Background  

Most people with a spinal cord injury rate neuropathic pain as one of the most difficult problems to manage and there are no medical treatments that provide satisfactory pain relief in most people. Furthermore, psychosocial factors have been considered in the maintenance and aggravation of neuropathic spinal cord injury pain. Psychological interventions to support people with spinal cord injury to deal with neuropathic pain, however, are sparse. The primary aim of the CONECSI (COping with NEuropathiC Spinal cord Injury pain) trial is to evaluate the effects of a multidisciplinary cognitive behavioural treatment programme on pain intensity and pain-related disability, and secondary on mood, participation in activities, and life satisfaction.  相似文献   
52.
Apical senescence in an early flowering line of pea, G2, is greatly delayed by short days. This behavior is controlled by two dominant genes. Apical senescence of ungrafted, insensitive (I) lines is unaffected by photoperiod. When I-type scions with one of the two required genes were grafted onto G2, apical senescence of the I-type was delayed in short days, but not in long days. Flowering of the I-type was unaffected. The apex of the G2 stock was unaffected as well. Apical senescence of an I-type line lacking both photoperiod genes was not delayed when grafted on G2 in short days. It is concluded that G2 plants grown in short days produce a graft-transmissible factor which delays apical senescence of photoperiodically insensitive lines.  相似文献   
53.
Efforts to define serological correlates of protection against COVID-19 have been hampered by the lack of a simple, scalable, standardised assay for SARS-CoV-2 infection and antibody neutralisation. Plaque assays remain the gold standard, but are impractical for high-throughput screening. In this study, we show that expression of viral proteases may be used to quantitate infected cells. Our assays exploit the cleavage of specific oligopeptide linkers, leading to the activation of cell-based optical biosensors. First, we characterise these biosensors using recombinant SARS-CoV-2 proteases. Next, we confirm their ability to detect viral protease expression during replication of authentic virus. Finally, we generate reporter cells stably expressing an optimised luciferase-based biosensor, enabling viral infection to be measured within 24 h in a 96- or 384-well plate format, including variants of concern. We have therefore developed a luminescent SARS-CoV-2 reporter cell line, and demonstrated its utility for the relative quantitation of infectious virus and titration of neutralising antibodies.  相似文献   
54.
55.
Human papillomavirus 58 (HPV58) ranks the second or third in East Asian cervical cancers. Current studies on HPV58 are scarce and focus on the prototype. Previously, we identified the three most common circulating HPV58 E7 strains contained amino acid alterations: G41R/G63D (51%), T20I/G63S (22%) and T74A/D76E (14%) respectively. Among them, the T20I/G63S variant (V1) had a stronger epidemiological association with cervical cancer. We therefore suggested that V1 possessed stronger oncogenicity than the other two variants. Here, we performed phenotypic assays to characterize and compare their oncogenicities with HPV58 E7 prototype. Our results showed that overexpression of V1 conferred a higher colony‐forming ability to primary murine epithelial cells than prototype (< 0.05) and other variants, implicating its higher immortalising potential. Further experiments showed that both V1 and prototype enhanced the anchorage‐independent growth of NIH/3T3 cells (< 0.001), implicating their stronger transforming power than the two other variants. Moreover, they possessed an increased ability to degrade pRb (< 0.001), which is a major effector pathway of E7‐driven oncogenesis. Our work represents the first study to compare the oncogenicities of HPV58 E7 prototype and variants. These findings deepened our understanding of HPV58 and might inform clinical screening and follow‐up strategy.  相似文献   
56.

Background

Androstenone is one of the major compounds responsible for boar taint, a pronounced urine-like odor produced when cooking boar meat. Several studies have identified quantitative trait loci (QTL) for androstenone level on Sus scrofa chromosome (SSC) 6. For one of the candidate genes in the region SULT2A1, a difference in expression levels in the testis has been shown at the protein and RNA level.

Results

Haplotypes were predicted for the QTL region and their effects were estimated showing that haplotype 1 was consistently related with a lower level, and haplotype 2 with a higher level of androstenone. A recombinant haplotype allowed us to narrow down the QTL region from 3.75 Mbp to 1.94 Mbp. An RNA-seq analysis of the liver and testis revealed six genes that were differentially expressed between homozygotes of haplotypes 1 and 2. Genomic sequences of these differentially expressed genes were checked for variations within potential regulatory regions. We identified one variant located within a CpG island that could affect expression of SULT2A1 gene. An allele-specific expression analysis in the testis did not show differential expression between the alleles of SULT2A1 located on the different haplotypes in heterozygous animals. However a synonymous mutation C166T (SSC6: 49,117,861 bp in Sscrofa 10.2; C/T) was identified within the exon 2 of SULT2A1 for which the haplotype 2 only had the C allele which was higher expressed than the T allele, indicating haplotype-independent allelic-imbalanced expression between the two alleles. A phylogenetic analysis for the 1.94 Mbp region revealed that haplotype 1, associated with low androstenone level, originated from Asia.

Conclusions

Differential expression could be observed for six genes by RNA-seq analysis. No difference in the ratio of C:T expression of SULT2A1 for the haplotypes was found by the allele-specific expression analysis, however, a difference in expression between the C over T allele was found for a variation within SULT2A1, showing that the difference in androstenone levels between the haplotypes is not caused by the SNP in exon 2.  相似文献   
57.
58.
59.
Deciduous fruit tree orchards located in the Pacific Northwest were surveyed over a 3-year period for the presence of ice nucleation-active (INA) bacteria. In the Yakima Valley, only about 30% of the fruit tree orchards contained INA bacteria (median population ca. 3 × 102 CFU/g [fresh weight]) in contrast to nearly 75% of the orchards in the Hood River Valley (median population ca. 5 × 103 CFU/g [fresh weight]). These INA populations ranged from less than 10 to over 106 CFU/g (fresh weight) of blossoms and, in Hood River Valley orchards, generally comprised over 10% of the total bacterial population. Populations of INA bacteria fluctuated during the year with highest levels developing on buds and flowers during the cool, wet spring, followed by a drop in populations during the warmer, drier, summer months and finally a gradual increase in the autumn. The INA bacteria persisted on dormant buds from which they again colonized young developing vegetative tissues. All INA bacteria were identified as Pseudomonas syringae. The frequency of ice nucleation at −5°C for these strains ranged from nearly every cell being INA to less than 1 in 107 cells. The median frequency of ice nucleation at −5°C was 104 cells per ice nucleus. The INA P. syringae strains from individual orchards were diverse with respect to bacteriocin typing and in ice nucleation frequency. The consistent absence of detectable INA bacteria or presence of low populations in most of the orchards surveyed during periods when critical temperatures (i.e., −2 to −5°C) were common indicated a limited role for INA bacteria in frost susceptibility of most Pacific Northwest orchards.  相似文献   
60.
Photoperiodic control of apical senescence in a genetic line of peas   总被引:11,自引:5,他引:6       下载免费PDF全文
An early flowering genetic line of peas (Pisum sativum L.), designated G2, has dominant genes at two different loci, both of which function in short days to greatly extend the reproductive phase and thus to delay apical senescence. Long days (18 hours) promote senescence in this line, but the effect is reversible by reinstatement of short days (9 hours) until 3 to 4 days before the apex senesces. The response to photoperiod was quantitative. Increasing the photoperiod from 14 to 18 hours led to a progressive decrease in the number of nodes formed prior to death of the apex. Induction of senescence was determined by the total number of hours of light and darkness rather than by the length of the dark period. Senescence required flower and fruit development as well as long days.  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