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   165篇
  免费   15篇
  180篇
  2022年   2篇
  2021年   8篇
  2020年   4篇
  2018年   6篇
  2017年   5篇
  2016年   8篇
  2015年   14篇
  2014年   14篇
  2013年   15篇
  2012年   17篇
  2011年   17篇
  2010年   6篇
  2009年   4篇
  2008年   7篇
  2007年   7篇
  2006年   10篇
  2005年   2篇
  2004年   10篇
  2003年   4篇
  2002年   4篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1996年   5篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1982年   1篇
  1974年   1篇
排序方式: 共有180条查询结果,搜索用时 0 毫秒
91.
92.
The objective of this study is to identify prognostic factors of treatment response to atomoxetine in improvement of health-related quality of life (HR-QoL), measured by the Child Health and Illness Profile-Child Edition Parent Report Form (CHIP-CE PRF) Achievement and Risk Avoidance domains, in children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Pooled data from 3 placebo-controlled trials and separate data from 3 open-label trials of atomoxetine in children and adolescents with ADHD were analyzed using logistic regression methods. Based on baseline impairment in the Achievement and/or Risk Avoidance domains (CHIP-CE PRF < 40 points), 2 subsamples of subjects were included. Treatment outcome was categorized as <5 points or ≥5 points increase in the CHIP-CE PRF Achievement and Risk Avoidance domains. Data of 190 and 183 subjects from the pooled sample, and 422 and 355 subjects from the open-label trials were included in the analysis of Achievement and Risk Avoidance domains. Baseline CHIP-CE subdomain scores proved to be the most robust prognostic factors for treatment outcome in both domains, based on data from the pooled sample of double-blind studies and from the individual open-label studies (odds ratios [OR] 0.74–1.56, p < 0.05; OR < 1, indicating a worse baseline score associated with worse odds of responding). Initial treatment response (≥25 % reduction in ADHD Rating Scale scores in the first 4–6 weeks) was another robust prognostic factor, based on data from the open-label studies (OR 2.99–6.19, p < 0.05). Baseline impairment in HR-QoL and initial treatment response can be early prognostic factors of atomoxetine treatment outcome in HR-QoL in children and adolescents with ADHD.  相似文献   
93.
94.
The female of Sciopemyia servulolimai (Damasceno & Causey), based on three specimens captured during an epidemiological research project in the state of Cear , Brazil, is described and illustrated for the first time.  相似文献   
95.
96.
The spider genus Latrodectus includes the widely known black widows, notorious because of the extreme potency of their neurotoxic venom. The genus has a worldwide distribution and comprises 30 currently recognized species, the phylogenetic relationships of which were previously unknown. Several members of the genus are synanthropic, and are increasingly being detected in new localities, an occurrence attributed to human mediated movement. In particular, the nearly cosmopolitan range of the brown widow, Latrodectus geometricus, is a suspected consequence of human transport. Although the taxonomy of the genus has been examined repeatedly, the recognition of taxa within Latrodectus has long been considered problematic due to the difficulty associated with identifying morphological features exhibiting discrete geographic boundaries. This paper presents, to our knowledge, the first phylogenetic hypothesis for the Latrodectus genus and is generated from DNA sequences of the mitochondrial gene cytochrome c oxidase subunit I. We recover two well-supported reciprocally monophyletic clades within the genus: (1) the geometricus clade, consisting of Latrodectus rhodesiensis from Africa, and its is sister species, the cosmopolitan L. geometricus, and (2) the mactans clade containing all other Latrodectus species sampled, including taxa occurring in Africa, the Middle East, Iberian Peninsula, Australia, New Zealand, and North and South America. Recovery of the geometricus and mactans clades is consistent with previous designations of species groups within the genus based on female genitalic morphology. All L. geometricus sampled, consisting of specimens from Africa, Argentina, North America, and Hawaii, were recovered as a strongly supported monophyletic group with minimal amounts of genetic divergence, corroborating the hypothesis that human transport has recently expanded the range of this species.  相似文献   
97.
Synechocystis strain PCC 6803 exhibits similar levels of cyclic AMP (cAMP) and cyclic GMP (cGMP). A thorough analysis of its genome showed that Cya2 (Sll0646) has all the sequence determinants required in terms of activity and purine specificity for being a guanylyl cyclase. Insertional mutagenesis of cya2 caused a marked reduction in cGMP content without altering the cAMP content. Thus, Cya2 represents the first example of a prokaryotic guanylyl cyclase.  相似文献   
98.
The present paper describes a new phlebotomine species, Evandromyia gaucha sp. nov., based on seven females found in the municipality of Ca?apava do Sul, state of Rio Grande do Sul, Brazil. The new species belong to rupicola series and differs from other sand flies of the genus Evandromyia due to the presence of a rounded spermatheca head with its size very close to that of the spermatheca body.  相似文献   
99.
Leaf-cutter ants are prolific and conspicuous constituents of Neotropical ecosystems that derive energy from specialized fungus gardens they cultivate using prodigious amounts of foliar biomass. The basidiomycetous cultivar of the ants, Leucoagaricus gongylophorus, produces specialized hyphal swellings called gongylidia that serve as the primary food source of ant colonies. Gongylidia also contain plant biomass-degrading enzymes that become concentrated in ant digestive tracts and are deposited within fecal droplets onto fresh foliar material as ants incorporate it into the fungus garden. Although the enzymes concentrated by L. gongylophorus within gongylidia are thought to be critical to the initial degradation of plant biomass, only a few enzymes present in these hyphal swellings have been identified. Here we use proteomic methods to identify proteins present in the gongylidia of three Atta cephalotes colonies. Our results demonstrate that a diverse but consistent set of enzymes is present in gongylidia, including numerous plant biomass-degrading enzymes likely involved in the degradation of polysaccharides, plant toxins, and proteins. Overall, gongylidia contained over three quarters of all biomass-degrading enzymes identified in the L. gongylophorus genome, demonstrating that the majority of the enzymes produced by this fungus for biomass breakdown are ingested by the ants. We also identify a set of 40 of these enzymes enriched in gongylidia compared to whole fungus garden samples, suggesting that certain enzymes may be particularly important in the initial degradation of foliar material. Our work sheds light on the complex interplay between leaf-cutter ants and their fungal symbiont that allows for the host insects to occupy an herbivorous niche by indirectly deriving energy from plant biomass.  相似文献   
100.
Familial amyloidotic polyneuropathy (FAP) is a lethal autosomal dominant type of amyloidosis resulting from the deposition of transthyretin (ATTR) variants in the peripheral and autonomic nervous systems. ATTR V30M-associated FAP exhibits marked genetic anticipation in some families, with clinical symptoms developing at an earlier age in successive generations. The genetic basis of this phenomenon in FAP is unknown. Anticipation has been associated with the dynamic expansion of trinucleotide repeats in several neurodegenerative disorders, such as Huntington disease, myotonic dystrophy, and fragile X syndrome. We have used the repeat expansion detection (RED) assay to screen affected members of Portuguese FAP kindreds for expansion of any of the ten possible trinucleotide repeats. Nine generational pairs with differences in their age of onset greater than 12 years and a control pair with identical ages of onset were tested. No major differences were found in the lengths of the ten trinucleotide repeats analyzed. The distribution of the maximal repeat sizes was consistent with reported studies in unrelated individuals with no known genetic disease. The present data do not support a role for trinucleotide repeat expansions as the molecular mechanism underlying anticipation in Portuguese FAP. Received: 13 December 1998 / Accepted: 23 March 1999  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