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排序方式: 共有417条查询结果,搜索用时 93 毫秒
31.
Co- and Fe-based alloys produced by powder technology are being widely used as a matrix for diamond-containing composites in cutting, drilling, grinding pplications, etc. The severe service conditions demand that the mechanical and tribological properties of these alloys be improved. Development of metal-matrix composites (MMCs) and alloys reinforced with nanoparticles is a promising way to resolve this problem. In this work, we have investigated the effect of nano-sized WC, ZrO2, Al2O3, and Si3N4 additives on the properties of sintered dispersion-strengthened Co- and Fe-based MMCs. The results show an increase in the hardness (up to 10 HRB), bending strength (up to 50%), wear resistance (by a factor of 2–10) and a decrease in the friction coefficient (up to 4-fold) of the dispersion-strengthened materials. The use of designed alloys as a binder of cutting diamond tools gave a 4-fold increment in the service life, without reduction in their cutting speed. 相似文献
32.
Vladimir G. Bespalov Ivan K. Alvovsky Grigory V. Tochilnikov Alexandr N. Stukov Ekaterina A. Vyshinskaya Alexandr L. Semenov 《International journal of hyperthermia》2018,34(5):545-550
Objectives: The choice of an optimal administration route for intraperitoneal (IP) chemotherapy and a suitable chemotherapeutic regime in the treatment of ovarian cancer remains a controversy. We investigated survival outcomes according to catheter intraperitoneal chemotherapy (CIPC), normothermic and hyperthermic chemoperfusion (NIPEC and HIPEC) with cytostatic drugs dioxadet and cisplatin in rats with transplantable ascitic ovarian cancer.Methods: Ascitic liquid containing 1?×?107 tumour cells was inoculated to female Wistar rats and 48?hours after rats received dioxadet and cisplatin at the maximum tolerated doses. Dioxadet at doses 1.5, 30 and 15?mg/kg and cisplatin at doses 4, 40 and 20?mg/kg body weight were administered for CIPC, NIPEC and HIPEC, respectively. Rats in the control groups received physiological saline and CIPC with physiological saline was regarded as the untreated control. The antitumor activity of the drugs was evaluated as an increase in average life expectancy (ALE). Analysis of the data was based primarily on Bayesian statistics and included Kaplan–Meier method, log-rank test and hazard ratio (HR) estimation.Results: Compared to the untreated control CIPC, NIPEC and HIPEC with dioxadet significantly increased ALE by 101316, 61524 and 1.71735 days, whereas with cisplatin by 61013, 122437 and –13523 days, respectively.Conclusions: Dioxadet and cisplatin show similar efficacy in the CIPC route. Compared with CIPC IP chemotherapy by chemoperfusions is more effective for both the drugs. Dioxadet in HIPEC showed highest survival benefit whereas largest effect during NIPEC is achieved with cisplatin. 相似文献
33.
Ardashev AV Makarenko AS Zhelyakov EG Shavarov AA 《Asian cardiovascular & thoracic annals》2010,18(6):529-535
Radiofrequency ablation of atrioventricular nodal reentrant tachycardia is commonly guided by slow and sharp bipolar potentials of the atrioventricular slow nodal pathway. We optimized the morphology of the guiding potential by unipolar mapping of the slow nodal pathway. We identified a novel unipolar dual-component atrial electrogram at the anterior limb of the coronary sinus ostium. The first component was a positive delta-wave type that corresponded to the isoelectric phase on a bipolar electrogram. The second component had fast biphasic morphology and corresponded to the R wave on a bipolar atrial electrogram. Of 104 consecutive patients with typical atrioventricular nodal reentrant tachycardia, 51 were treated with ablation guided by the novel potential, and 53 underwent ablation using the conventional technique. There was no recurrence of tachycardia in any of these patients. In those treated by the novel potential, there was significantly less radiofrequency power applied and a shorter duration of application than in patients treated by the traditional approach. The novel approach to mapping and ablation of the slow nodal pathway in atrioventricular nodal reentrant tachycardia guided by unipolar recording was safe and effective, and comparable to the traditional technique. 相似文献
34.
Yulia M. Ulybina Ekatherina Sh. Kuligina Nathalia V. Mitiushkina Nathalia Yu. Sherina Grigoriy A. Yanus Tatiana V. Gorodnova Anna S. Katanugina Andrey V. Koloskov Alexandr V. Togo Evgeny N. Imyanitov 《Experimental gerontology》2010
Our previous studies, which included genotyping of multiple coding apoptotic gene polymorphisms, unexpectedly demonstrated a depletion of heterozygous CASP5 Ala90Thr (rs507879, c.268 G > A) genotypes in elderly subjects. Present investigation was aimed to validate this trend. An analysis of 510 subjects aged 75–103 years revealed 205 (40%) CASP5 Ala90Thr heterozygotes as compared to 254 (50%) expected from the minor allele frequency 0.470 (p = 0.000014). This deviation was not observed in 549 middle-aged (18–50 years) controls (270 (49%) heterozygotes observed vs. 274 (50%) expected; minor allele frequency 0.475; p = 0.743). Unfavorable significance of CASP5 heterozygous genotype may be explained by the role of the caspase-5 in inflammation-related processes. Almost all prior gene-longevity association studies focused on discrimination between “good” and “bad” gene variants. Here we present a distinct situation, where the combination of alternative alleles (i.e., heterozygosity) appears to be unfavorable as compared to the homozygous carriership of either gene variant. 相似文献
35.
Despite the accumulating data on the molecular and cell biological characteristics of neural stem/progenitor cells, their electrophysiological properties are not well understood. In the present work, changes in the membrane properties and current profiles were investigated in the course of in vitro-induced neuron formation in NE-4C cells. Induction by retinoic acid resulted in neuronal differentiation of about 50% of cells. Voltage-dependent Na+ currents appeared early in neuronal commitment, often preceding any morphological changes. A-type K+ currents were detected only at the stage of network formation by neuronal processes. Flat, epithelial- like, nestin-expressing progenitors persisted beside differentiated neurons and astrocytes. Stem/progenitor cells were gap junction coupled and displayed large, symmetrical, voltage-independent currents. By the blocking of gap junction communication, voltage-independent conductance was significantly reduced, and delayed-rectifying K+ currents became detectable. Our data indicate that voltage-independent symmetrical currents and gap junction coupling are characteristic physiological features of neural stem and progenitor cells regardless of the developmental state of their cellular environment. 相似文献
36.
Sokolenko AP Rozanov ME Mitiushkina NV Sherina NY Iyevleva AG Chekmariova EV Buslov KG Shilov ES Togo AV Bit-Sava EM Voskresenskiy DA Chagunava OL Devilee P Cornelisse C Semiglazov VF Imyanitov EN 《Familial cancer》2007,6(3):281-286
Previous studies indicate that founder mutations may play a noticeable role in breast cancer (BC) predisposition in Russia.
Here we performed a systematic analysis of eight recurrent mutations in 302 BC cases (St.-Petersburg, Russia), which were
selected due to the presence of clinical indicators of hereditary disease (bilaterality and/or early onset (≤40 years) and/or
family history). BC-associated alleles were revealed in 46 (15.2%) women. BRCA1 5382insC mutation was detected in 29 (9.6%)
patients, CHEK2 1100delC in 9 (3.0%), BRCA1 4153delA in 3 (1.0%), CHEK2 IVS2+1G>A in 2 (0.7%), and BRCA1 185delAG, BRCA2 6174delT
and NBS1 657del5 in 1 (0.3%) patient each. No cases with BRCA1 300T>G (C61G) mutation was identified. The obtained data suggest
that a significant fraction of hereditary BC cases in Russia can be diagnosed using only a limited number of simple PCR tests. 相似文献
37.
38.
Antonov AS Kalinovsky AI Stonik VA Afiyatullov SS Aminin DL Dmitrenok PS Mollo E Cimino G 《Journal of natural products》2007,70(2):169-178
Nine new triterpene glycosides, erylosides F1-F4 (1-4), M (5), N (6), O (7), P (8), and Q (9), along with previously known erylosides F (10) and H (11) were isolated from the sponge Erylus formosus collected from the Mexican Gulf (Puerto Morelos, Mexico). Structures of 1-4 were determined as the corresponding biosides having aglycons related to penasterol with additional oxidation patterns in their side chains. Erylosides 5-9 contain new variants of carbohydrate chains with three (5, 6), four (7), and six (8, 9) sugar units, respectively. Erylosides 5, 7, 8, and 6, 9 contain 14-carboxy-24-methylenelanost-8(9)-en-3beta-ol and penasterol as aglycons, respectively. In contrast with its epimer 2, the compound 3 induced the early apoptosis of Ehrlich carcinoma cells at a concentration of 100 microg/mL, while 1 and 10 activated the Ca2+ influx into mouse spleenocytes (130% of the control) at the same doses. 相似文献
39.
Suspitsin EN Sokolenko AP Togo AV Lazareva YR Turkevich EA Matsko DE Henrich KO Borresen-Dale AL Schwab M Cornelisse CJ Imyanitov EN 《International journal of cancer. Journal international du cancer》2007,120(2):297-302
Amplification of HER2, C-MYC and CCND1 oncogenes is a hallmark of breast cancer (BC); however, its involvement in the bilateral form of this disease has not been investigated yet. In this study, 50 bilateral BC (biBC) pairs (100 tumors) and 72 control unilateral BC were examined using real-time PCR analysis of microdissected archival tissues. In biBC, the frequency of >3-fold oncogene amplification was 6/100 (6%) for HER2, 6/100 (6%) for C-MYC and 7/100 (7%) for CCND1. Altogether, 18/100 (18%) biBC tumors had increased gene dosage of at least one oncogene. Tumors forming synchronous biBC pairs had amplification in 11/46 cases (24%). In 3 of 8 patients with amplification-positive carcinomas, the amplification was detected in both neoplasms: 2 biBC had concordant activation of the same oncogene (HER2 and CCND1, respectively), and in the remaining case distinct oncogenes were affected (HER2 and C-MYC). In contrast, amplifications in metachronous biBC were strongly discordant: none of 27 first carcinomas carried this abnormality, while the frequency of amplification in second tumors (7/27; 26%) was similar to the one observed in unilateral BC (20/72; 28%). The trend toward concordance of oncogene amplification status in synchronous but not in metachronous biBC pairs can be explained by the nearly identical natural history of the disease in simultaneously arising tumors. The skewed pattern of amplifications in metachronous biBC might be attributed to their association with adverse BC prognosis; it appears that only patients with amplification-negative first BC have sufficient chances to survive until the development of the contralateral carcinoma. 相似文献
40.