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   32篇
  免费   0篇
化学工业   12篇
机械仪表   4篇
能源动力   1篇
轻工业   5篇
无线电   3篇
一般工业技术   1篇
冶金工业   5篇
自动化技术   1篇
  2022年   4篇
  2021年   5篇
  2020年   1篇
  2019年   1篇
  2013年   2篇
  2012年   4篇
  2011年   2篇
  2009年   1篇
  2008年   2篇
  2007年   1篇
  2003年   1篇
  2002年   1篇
  2001年   1篇
  1998年   1篇
  1997年   2篇
  1994年   1篇
  1993年   1篇
  1986年   1篇
排序方式: 共有32条查询结果,搜索用时 31 毫秒
1.
The control of the fungal contamination on crops is considered a priority by the sanitary authorities of an increasing number of countries, and this is also due to the fact that the geographic areas interested in mycotoxin outbreaks are widening. Among the different pre- and post-harvest strategies that may be applied to prevent fungal and/or aflatoxin contamination, fungicides still play a prominent role; however, despite of countless efforts, to date the problem of food and feed contamination remains unsolved, since the essential factors that affect aflatoxins production are various and hardly to handle as a whole. In this scenario, the exploitation of bioactive natural sources to obtain new agents presenting novel mechanisms of action may represent a successful strategy to minimize, at the same time, aflatoxin contamination and the use of toxic pesticides. The Aflatox® Project was aimed at the development of new-generation inhibitors of aflatoxigenic Aspergillus spp. proliferation and toxin production, through the modification of naturally occurring molecules: a panel of 177 compounds, belonging to the thiosemicarbazones class, have been synthesized and screened for their antifungal and anti-aflatoxigenic potential. The most effective compounds, selected as the best candidates as aflatoxin containment agents, were also evaluated in terms of cytotoxicity, genotoxicity and epi-genotoxicity to exclude potential harmful effect on the human health, the plants on which fungi grow and the whole ecosystem.  相似文献   
2.
The brain-derived neurotrophic factor (BDNF) was discovered in the last century, and identified as a member of the neurotrophin family. BDNF shares approximately 50% of its amino acid with other neurotrophins such as NGF, NT-3 and NT-4/5, and its linear amino acid sequences in zebrafish (Danio rerio) and human are 91% identical. BDNF functions can be mediated by two categories of receptors: p75NTR and Trk. Intriguingly, BDNF receptors were highly conserved in the process of evolution, as were the other NTs’ receptors. In this review, we update current knowledge about the distribution and functions of the BDNF-TrkB system in the sensory organs of zebrafish. In fish, particularly in zebrafish, the distribution and functions of BDNF and TrkB in the brain have been widely studied. Both components of the system, associated or segregated, are also present outside the central nervous system, especially in sensory organs including the inner ear, lateral line system, retina, taste buds and olfactory epithelium.  相似文献   
3.
BACKGROUND: Myocardial revascularization in patients with left ventricular failure (ejection fraction < 30%) offers survival comparable to heart transplantation. The functional outcome, however, has yet to be determined. In order to assess the clinical results in patients with LVEF < 30% undergoing coronary artery bypass grafts (CABG), 101 consecutive patients operated between 1/91 and 1/97 were reviewed retrospectively. METHODS: The patients were stratified according to presentation: 65 pts had angina (Group 1) and 36 congestive failure (Group 2). Mean age (62 +/- 7 vs 60 +/- 8 yrs), sex (90 vs 88% male), LVEF (0.28 +/- 0.04 vs 0.29 +/- 0.04), prior myocardial infarction (1.2 +/- 0.4 vs 1.2 +/- 0.5 episodes/pt), presence of vital myocardium at scintiscan or low-dose dobutamine echocardiography (92 vs 93%), need for preoperative IABP (3.1 vs 8.3%), aortic cross-clamp (53 +/- 21 vs 60 +/- 21 min) and cardiopulmonary bypass (104 +/- 31 vs 114 +/- 36 min) times were comparable. RESULTS: There was only 1 (1%) perioperative death due to low-output syndrome. Eleven pts (6 vs 5, Group 1 vs Group 2) had postoperative low-output syndrome, requiring IABP in 7 pts (4 vs 3). There were 14 (10 vs 4, Group 1 vs Group 2) deaths during follow-up (29 +/- 19 months, range 2-67), with an overall actuarial survival of 91 +/- 4 vs 100% at 1 yr and 74 +/- 9 vs 78 +/- 10% at 5 yrs in Group 1 vs Group 2, respectively (p = ns). Actuarial symptom-free survival was 89 +/- 4 vs 84 +/- 6% at 1 yr and 49 +/- 9 vs 28 +/- 11% at 5 yrs, respectively (p = 0.05). Despite the high recurrence of congestive failure (22 vs 66% in Group 1 vs Group 2, p = 0.004), improvement in functional class (3.1 +/- 0.8 vs 1.5 +/- 0.7 in Group 1 and 2.7 +/- 0.7 vs 1.8 +/- 0.5 in Group 2) and LVEF (0.28 +/- 0.04 vs 0.38 +/- 0.04 in Group 1 and 0.29 +/- 0.04 vs 0.40 +/- 0.06 in Group 2) was found in both groups at follow-up. CONCLUSIONS: In spite of improving early and late survival after revascularization for ischemic left ventricular failure, patients presenting with congestive failure have an unsatisfactory symptom-free survival. Further studies are necessary to ascertain the relative indications to revascularization or transplantation in this specific patient subgroup.  相似文献   
4.
We consider initial timing acquisition in discrete-sequence code-division multiple-access (DS-CDMA) when propagation is affected by multipath and fading, and where the base-station broadcasts a synchronization pilot signal in the form of bursts of modulated chips transmitted periodically and separated by long silent intervals. Subject to certain simplifying assumptions, we derive the maximum-likelihood (ML) estimator by solving a constrained maximization problem. Our ML timing estimator has constant complexity per observation sample. The relation to other estimation methods is addressed, and performance comparisons are provided by simulation. The proposed estimator yields good performance independently of the multipath-intensity profile of the channel, provided that the delay spread is not larger than a given maximum spread. Moreover, our estimator is fairly robust to the mismatch in the fading Doppler spectrum and provides good performance for both fast and slow fading  相似文献   
5.
微软与开源的关系,一方面,微软不时的向开源社区伸出橄榄枝,另一方对开源厂商起诉不断。谁能知道,微软究竟是开源的朋友还是敌人呢?  相似文献   
6.
7.
Abstract: Extra virgin olive oil (EVOO) is recognized as one of the healthiest foods for its high content of antioxidants, which forestall and slow down radical formation. Free radical‐initiated oxidation is considered one of the main causes of rancidity in fats and oils. As a consequence, reliable protocols for the investigation of oil oxidation based on selective, noninvasive, and fast methods are highly desirable. Here we report an experimental approach based on UV‐Vis absorbance, steady‐state fluorescence, and electron paramagnetic resonance (EPR) spectroscopy for studying oxidation processes induced by temperature for a period up to 35 d on Sicilian EVOO samples. We followed the decrease in β‐carotene content during incubation time and observed changes in polyphenols and tocopherols during the oxidation processes, focusing on the time scale of those changes. Using EPR spectroscopy, the free radical formation in different oil samples is reported, providing a fingerprint for both the antioxidant content and temporal features of the oxidation process at its early stage. Practical Application: We monitor β‐carotene and chlorophyll in an auto‐oxidation process. A protocol based on spectroscopic measurements is presented and can be used for the quality control process of commercial olive oil.  相似文献   
8.
This paper describes a software-radio architecture developed for providing real-time wide-band radio communication capabilities in a form attractive for advanced 3G systems research. It is currently being used to implement signaling methods and protocols similar, but not limited to, evolving 3G radio standards (e.g. umts, cdma2000). An overview of the hardware system is provided along with example software implementations on both high-perfo-mance DSP systems and conventional microprocessors.  相似文献   
9.
10.
The European sea bass, a member of the Moronidae family, is a food fish, considered one of the first models for the intensive breeding in salt water. It has nowadays an important and increasing presence in the international fishing markets. Sea basses are carnivorous, feeding on little fishes and invertebrates. Considering the important role of the tongue during the intraoral transport and the swallowing of food, scarce data are present in literature about its morphology. The aim of this study was to analyze the morphology of the tongue by means of scanning electron and light microscopy. Adult sea basses were obtained from the aquarium of the Sicilian Center of Experimental Ichthyiopathology of the University of Messina. The fishes were anaesthetized with MS 222 and the heads were then quickly removed and processed for the paraffin embedding and SEM processing. Three different tongue regions could be distinguished: an apex, a body, and a root. Scanning electron and light microscopy showed the presence of numerous canine-like teeth, surrounded by taste buds and numerous fungiform and conical papillae. The teeth were curved and their tips were posteriorly oriented. The results confirm, in teleosts too, the fundamental role of the tongue in the mechanics of food ingestion. Moreover, the presence of taste buds demonstrates the interaction of food processing and taste. These data could be a potential source to identify new and better methods of nutrition in the breeding of this fish.  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