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   129篇
  免费   17篇
  2022年   1篇
  2021年   4篇
  2020年   5篇
  2019年   4篇
  2018年   8篇
  2017年   9篇
  2016年   5篇
  2015年   8篇
  2014年   11篇
  2013年   16篇
  2012年   9篇
  2011年   6篇
  2010年   10篇
  2009年   5篇
  2008年   7篇
  2006年   6篇
  2005年   3篇
  2004年   1篇
  2003年   6篇
  2001年   2篇
  2000年   2篇
  1998年   1篇
  1995年   3篇
  1992年   1篇
  1988年   1篇
  1987年   2篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1979年   1篇
  1978年   1篇
  1974年   2篇
  1972年   1篇
  1971年   1篇
  1907年   1篇
排序方式: 共有146条查询结果,搜索用时 15 毫秒
61.

Purpose

To assess the results of tracheal cancer patients treatment and factors influencing prognosis.

Background

Primary malignant neoplasms of the trachea are rare. The treatment of choice for tracheal carcinomas is resection. Radiation therapy is recommended as a part of radical treatment or for palliation of symptoms.

Materials and methods

Between 1962 and 2006, 50 patients diagnosed with tracheal cancer were treated at the Centre of Oncology in Krakow. The analysis focused on locoregional recurrence-free survival (LRRFS), disease free survival (DFS) and overall survival (OS). Survival rates, univariate and multivariate analyses of prognostic factors were performed using the Kaplan–Meier method, the log rank test and Cox''s proportional hazard method, respectively.For over 40 years, patients were treated using different modalities: surgery followed by radiotherapy (6%), radiotherapy (78%), chemoradiotherapy (8%), and symptomatic treatment (8%).

Results

The 5-year LRRFS was 18%, DFS was 15% and OS was 17%. gender (favoured females) was the only prognostic factor for LRRFS. For OS, the independent prognostic factors were performance status (favoured Karnofsky higher than 80), stage and year of start of the treatment (later than 1988 vs. earlier – 5-year OS 20% vs. 12%).5-year OS in the following (strongly differentiated over the time) treatment modalities were: surgery followed by radiotherapy (66%), radiotherapy (16%), chemoradiotherapy (0%), and symptomatic treatment (0%).Of 44 patients treated with radiotherapy symptomatic partial response was observed in 32 patients and follow-up imaging studies revealed complete response in 5 patients, partial response in 25, stable disease in 4 or progressive disease in 4.

Conclusions

Radical treatment in patients in early stage and good performance status seems to be correlated with the improvement of survival. However, despite the fact that results of treatment are poor, radiotherapy offers symptomatic improvement.  相似文献   
62.
In this report, we present the results of our investigations on the effect of Mg pretreatment on Cd and bioelements (Cu and Zn) contents in kidney of mice exposed to acute and subacute Cd intoxication. Acute intoxication was performed on male Swiss mice given a single oral dose of 20 mg Cd/kg body weight and mice given the same dose of Cd but pretreated with 40 mg Mg/kg body weight. For subacute intoxication one group of mice was given 10 mg Cd/kg body weight every day, for 2 wk, and the other one received the same dose of Cd after oral Mg intake of 20 mg/kg body weight. Cd, Cu, and Zn content was determined in kidney by atomic absorption spectrophotometry. In acute Cd intoxication, Mg pretreatment resulted in significant decrease of Cd in kidney after 4 and 6 h, compared with animals given only Cd. Under the condition of subacute Cd intoxication, Mg supplementation reduced Cd kidney content after 2 wk for about 30%, compared with animals treated with Cd only. The effect of Mg on Cu and Zn kidney content was also beneficial.  相似文献   
63.
Summary Sour orange (Citrus aurantium L.) rootstock has historically been a widely utilized eitrus rootstock throughout the world due to its wide soil adaptability and superior horticultural performance. However, quick-decline isolates of citrus tristeza virus (CTV) have demolished entire industries of sour orange rootstock in some countries, including Brazil and Venezuela. CTV is presently destroying millions of trees of sour orange rootstock in Florida and threatens the citrus industries of Texas and Mexico, where sour orange is the predominant rootstock. Efforts to replace sour orange rootstock are combining traditional breeding and biotechnology approaches, including somatic hybridization and transformation. Molecular techniques have confirmed that sour orange is probably a hybrid of mandarin and pummelo. A major focus of our program continues to be the somatic hybridization of superior mandarins with pre-selected pummelo parents. Here, we report the regeneration of allotetraploid somatic hybrid plants from seven new mandarin+pummelo combinations and one new sweet orange+pummelo combination. All new somatic hybrids were confirmed by leaf morphology, ploidy analysis via flow cytometry, and random amplified polymorphic DNA analysis to show nuclear contributions from both parents in corresponding hybrids. These new somatic hybrids are being propagated by tissue culture and/or rooted cuttings for further evaluation of disease resistance and horticultural performance in field trials.  相似文献   
64.
An isolated population of the three‐spined stickleback Gasterosteus aculeatus in Croatia was found to have a high incidence of specimens either having a fourth dorsal spine or showing remnants of a fourth spine. Juvenile individuals showed a 9·4% incidence of a fourth spine. The population was examined for asymmetry of the skeletal defensive complex in order to determine whether the additional spine could be the result of developmental instability, a response to predation or environmental conditions.  相似文献   
65.
The complete mitochondrial DNA (mtDNA) genome of the Eunapius subterraneus (Porifera, Demospongiae), a unique stygobitic sponge, was analyzed and compared with previously published mitochondrial genomes from this group. The 24,850 bp long mtDNA genome is circular with the same gene composition as found in other metazoans. Intergenic regions (IGRs) comprise 24.7% of mtDNA and are abundant with direct and inverted repeats and palindromic elements as well as with open reading fames (ORFs) whose distribution and homology was compared with other available mt genomes with a special focus on freshwater sponges. Phylogenetic analyses based on concatenated amino acid sequences from 12 mt protein genes placed E. subterraneus in a well-supported monophyletic clade with the freshwater sponges, Ephydatia muelleri and Lubomirskia baicalensis. Our study showed high homology of mtDNA genomes among freshwater sponges, implying their recent split.  相似文献   
66.
As part of ongoing studies in developing new antimicrobials, a class of structurally novel 4-thiazolidinone derivatives incorporating three known bioactive nuclei such as thiazole, thiazolidinone and adamantane was synthesized by the multi-step reaction protocol, already reported in the literature. NMR and Molecular Modeling techniques were employed for structure elucidation and Z/E potential isomerism configuration of the analogues. Evaluation of antibacterial and antifungal activity showed that almost all compounds exhibited better results than reference drugs thus they could be promising candidates for novel drugs.  相似文献   
67.
68.
Early development of the endemic dace Telestes karsticus is described in a Dinaric karst stream in Croatia. Larvae were acquired from successful rearing in an aquarium. Basic morphometric and meristic measures of larvae were taken during 55 days of observation. The mean total length of larvae at the time of hatching was 6.45 mm. The yolk sac was completely absorbed in all larvae by day 9 post-hatching (PH), when the mouth also opened and independent feeding and intestinal function were observed. Flexion of the urostyle was completed between days 12–16 PH. The caudal fin became completely forked on day 23 PH. Formation of fin rays was complete on day 48 PH when fish fully resembled juvenile specimens. The number of soft ray fins corresponds to the adult. Understanding the early development is particularly valuable in assessing environmental impacts and recovering of this endangered species and it is essential for effective monitoring and its conservation. This is the first report of the early development for the endemic Telestes karsticus, pointing out the importance of the obtained results for the effective conservation of the species.  相似文献   
69.
The utility of the Inter Simple Sequence Repeat-Polymerase Chain Reaction (ISSR-PCR) was explored in order to determine genetic variation in six species of the genus Apodemus (A. flavicollis, A. sylvaticus, A. uralensis, A. agrarius, A. mystacinus and A. epimelas) at the individual level, population level, in separate geographic samples and in the species as a whole. Six optimized primers produced highly reproducible and polymorphic DNA markers with 98.3% polymorphic bands on a total sample of 91 individuals from 32 localities in Europe and Asia. Moreover, each primer allowed for an exact diagnosis of each of the six Apodemus species and thus provides a simple and reliable tool for the hitherto problematic discrimination of species from the subgenus Sylvaemus. Genetic distances between species ranged from 0.079, among the closely related A. flavicollis and A. sylvaticus, to 0.203 between A. mystacinus and A. agrarius. A. flavicollis, A. uralensis and A. sylvaticus display a strong population substructure. The range of genetic distances among geographic samples within last two species reaches the values obtained for closely related species. ISSR markers proved to be a simple and reliable tool for species diagnosis, as well as for estimating genetic diversity below the species level and for closely related species, but they showed questionable reliability for larger genetic distances.  相似文献   
70.
The Kdp system of Escherichia coli is composed of the high‐affinity K+ transporter KdpFABC and the two regulatory proteins KdpD (sensor kinase) and KdpE (response regulator), which constitute a typical two‐component system. The kdpFABC operon is induced under K+‐limiting conditions and, to a lesser extent, under high osmolality in the medium. In search for the stimulus sensed by KdpD, we studied the inhibitory effect of extracellular K+ on the Kdp system at pH 6.0, which is masked by unspecific K+ transport at higher pH values. Based on KdpD derivatives carrying single aspartate replacements in the periplasmic loops which are part of the input domain, we concluded that the inhibition of the Kdp system at extracellular K+ concentrations above 5 mM is mediated via KdpD/KdpE and not due to inhibition of the K+‐transporting KdpFABC complex. Furthermore, time‐course analyses of kdpFABC expression revealed that a decline in the extracellular K+ concentration efficiently stimulates KdpD/KdpE‐mediated signal transduction. In this report we provide evidence that the extracellular K+ concentration serves as one of the stimuli sensed by KdpD.  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