维普中文期刊产品整合服务
102篇 您的检索式:作者名="Lou Lei"
    题名 作者 年代 出处 被引量
1Genome-wide identification of CRISPR/Cas9 off-targets in human genome显示文摘Jinzhi Duan Guangqing Lu Zhan Xie Mingliang Lou Jiao Luo Lei Guo Yu Zhang 2014Cell Research2014,24,8:27
2Prevalence and Factors Associated with Female Sexual Dysfunction in Beijing, China显示文摘Wen-Jia Lou Bo Chen Lan Zhu Shao-Mei Han Tao Xu Jing-He Lang Lei Zhang 2017Chinese Medical Journal2017,,12:25
3Epidemiological characteristics of thyroid nodules and risk factors for malignant nodules: a retrospective study from 6 304 surgical cases显示文摘Huan Qin Wang Kun Lou Fuchen Zhang Li Huang Qingxian Han Yunfeng Sun Hancheng Zhu Lei Lin Peng Song Jun Liu Fuqiang Wang Qian Hou Weikai 2014Chinese Medical Journal2014,,12:20
4Analysis of CD8+ Treg cells in patients with ovarian cancer: a possible mechanism for immune impairment显示文摘Shuping Zhang 2015Cellular & Molecular Immunology2015,12,5:17
5Usefulness of interferon-γrelease assay for the diagnosis of sputum smear-negative pulmonary and extra-pulmonary TB in Zhejiang Province,China显示文摘Background:Quick diagnosis of smear-negative pulmonary tuberculosis(TB)and extra-pulmonary TB are urgently needed in clinical diagnosis.Our research aims to investigate the usefulness of the interferon-γrelease assay(IGRA)for the diagnosis of smear-negative pulmonary and extra-pulmonary TB.Methods:We performed TB antibody and TB-IGRA tests on 389 pulmonary TB patients(including 120 smear-positive pulmonary TB patients and 269 smear-negative pulmonary TB patients),113 extra-pulmonary TB patients,81 patients with other pulmonary diseases and 100 healthy controls.Blood samples for the TB-Ab test and the TB-IGRA were collected,processed,and interpreted according to the manufacturer’s protocol.Results:The detection ratio of smear-positive pulmonary TB patients and smear-negative pulmonary TB patients were 90.8%(109 of 120)and 89.6%(241 of 269),respectively.There was no statistically significant difference of its performance between these two sample sets(P>0.05).The detection ratio of positive TB patients and extra-pulmonary TB patients were 90.0%(350 of 389)and 87.6%(99 of 113),respectively,which was not significantly different(P>0.05).Conclusions:In this work,the total detection ratio using TB-IGRA was 89.4%,therefore TB-IGRA has diagnostic values in smear-negative pulmonary TB and extra-pulmonary TB diagnosis.Lei Ji Yong-Liang Lou Zhong-Xiu Wu Jin-Qin Jiang Xing-Li Fan Li-Fang Wang Xiao-Xiang Liu Peng Du Jie Yan Ai-Hua Sun 2017Infectious Diseases of Poverty2017,6,1:12
6The unconformity in Miocene sequence of western Qaidam Basin and its tectonic significance显示文摘An angular unconformity has been identified between the upper and the lower Youshashan Formation based on the study of the regional geology, drillhole, and geophysical data of the Altyn Tagh Mountain foreland, western Qaidam Basin. The distribution of the unconformity, the contacts between the upper and the lower Youshashan Formation, and its relation to the characteristics of the paleo-structure belts suggest a close relationship between the unconformities in the southern flank of the Altyn Tagh Mountain in the west of the Qaidam Basin and the activity of the Altyn Tagh Fault. It was the same time when the Atlyn Tagh Fault Zone was transformed from regional uplifting to rapid-strike-slipping movement during the Miocene, resulting in the cessation of the regional uplift and subsequent massive regional transgression during the deposition of the upper Youshashan Formation, which unconformably overlies (onlaps) the underlying strata of different ages.WANG Liang XIAO AnCheng GONG QingLin LIU Dong WU Lei ZHOU SuPing SHEN ZhongYan LOU QianQian SUN XiaoWen 2010Science China Earth Sciences2010,53,8:10
7Prioritizing natural-selection signals from the deep-sequencing genomic data suggests multi-variant adaptation in Tibetan highlanders显示文摘Human genetic adaptation to high altitudes(>2500 m)has been extensively studied over the last few years,but few functional adaptive genetic variants have been identified,largely owing to the lack of deep-genome sequencing data available to previous studies.Here,w e build a list of putative adaptive variants,including 63 missense,7 loss-of-function;1,298 evolutionarily conserved variants and 509 expression quantitative traits loci.Notably,the top signal of selection is located in TMEM 247,a transmembrane protein-coding gene.The Tibetan version of TMEM 247 harbors one high-frequency(76.3%)missense variant,rsl 16983452(c.248C>T;p.Ala83Val);with the T allele derived from archaic ancestry and carried by>94%of Tibetans but absent or in low frequencies(<3%)in non-Tibetan populations.The rsl 16983452-T is strongly and positively correlated with altitude and significantly associated with reduced hemoglobin concentration(p=5.78×10^-5),red blood cell count(p=5.72×10^-7)and hematocrit(p=2.57×10^-6).In particular,TMEM247-rs 116983452 shows greater effect size and better predicts the phenotypic outcome than any E P A S1 variants in association with adaptive traits in Tibetans.Modeling the interaction between TM£M247-rsl 16983452 and EPAS1 variants indicates weak but statistically significant epistatic effects.Our results support that multiple variants may jointly deliver the fitness of the Tibetans on the plateau,where a complex model is needed to elucidate the adaptive evolution mechanism.Lian Deng Chao Zhang Kai Yuan Yang Gao Yuwen Pan Xueling Ge Yaoxi He Yuan Yuan Yan Lu Xiaoxi Zhang Hao Chen Haiyi Lou Xiaoji Wang Dongsheng Lu Jiaojiao Liu Lei Tian Qidi Feng Asifullah Khan Yajun Yang Zi-Bing Jin Jian Yang Fan Lu Jia Qu Longli Kang Bing Su Shuhua Xu 2019National Science Review2019,6,6:9
8Interventional endoscopic ultrasound for a symptomatic pseudocyst secondary to gastric heterotopic pancreas显示文摘Heterotopic pancreas(HP) is a relatively uncommon entity that is defined as pancreatic tissue without a true anatomical or vascular connection to the pancreas. HP does not cause symptoms in most cases but can occasionally produce various manifestations, including nausea, vomiting, abdominal pain, and even heterotopic pancreatitis. Here, we report an unusual case in which heterotopic pancreatitis complicated by the formation of a pseudocyst that caused gastric outlet obstruction was diagnosed based on serum hyperamylasemia and findings from endoscopic ultrasonography(EUS)-guided fine needle aspiration(EUS-FNA) cytology. EUS-guided single pigtail stent insertion was successfully performed for recurrent gastric outlet obstruction. The patient has remained healthy and symptom-free during 4 years of surveillance. In the context of the relevant literature, the described case is a rare case of HP complicated by a pseudocyst treated via EUS-FNA and stent insertion.hang-bin jin lei lu jian-feng yang qi-feng lou jing yang hong-zhang shen xiao-wei tang xiao-feng zhang 2017World Journal of Gastroenterology2017,23,34:9
9Micro/Nanofiber Optical Sensors显示文摘As a low-dimensional optical fiber with diameter close to or below the wavelength of light,optical micro/nanofiber(MNF)offers a number of favorable properties for optical sensing,which have been exploited in a variety of sensing applications,including physical,chemical,and biological sensors.In this paper we review the principles and applications of silica,glass,and polymer optical micro/nanofibers for physical and chemical sensing.Lei ZHANG Jingyi LOU Limin TONG 2011Photonic Sensors2011,1,1:8
10Effects of H pylori infection on gap-junctional intercellular communication and proliferation of gastric epithelial cells in vitro显示文摘AIM: To explore the effects of H pylori infection on gap-junctional intercellular communication (GJIC) and proliferation of gastric epithelial cells in vitro. METHODS: A human gastric epithelial cell line (SGC-7901) cultured on coverslips was exposed overnight to intact H pylori (CagA+ or CagA-strains) and sonicated extracts,respectively. GJIC between the cells was detected by fluorescence redistribution after photobleaching (FRAP) technique. Proliferation of SGC cells was determined by methylthiazolyl tetrazolium (MTT) assay. RESULTS: When compared with control in which cells were cultured with simple medium alone,both CagA+ and CagA-H pylori isolates could inhibit GJIC (CagA+: F = 57.98,P < 0.01; CagA-: F = 29.59,P < 0.01) and proliferation (CagA+: F = 42.65,P < 0.01; CagA-: F = 58.14,P < 0.01) of SGC-7901 cells. Compared with CagA-strains,CagA+ H pylori more significantly down-regulated GJIC of gastric cells (intact H pylori: t = 13.86,P < 0.01; sonicated extracts: t = 11.87,P < 0.01) and inhibited proliferation gastric cells to a lesser extent in vitro (intact H pylori: t = 3.06,P < 0.05; sonicated extracts: t = 3.94,P < 0.01). CONCLUSION: Compared with CagA-H pylori strains,CagA+ strains down-regulate GJIC of gastric epithelia cells more significantly and inhibit proliferation of gastric cells to a lesser extent in vitro . H pylori ,especially CagA+ strains,may play an important role in gastric carcinogenesis.Ran Tao Miao-Feng Hu Jin-Tu Lou Yong-Liang Lei 2007World Journal of Gastroenterology2007,13,41:8
11The role of non-coding RNAs in drug resistance of oral squamous cell carcinoma and therapeutic potential显示文摘Oral squamous cell carcinoma(OSCC),the eighth most prevalent cancer in the world,arises from the interaction of multiple factors including tobacco,alcohol consumption,and betel quid.Chemotherapeutic agents such as cisplatin,5-fluorouracil,and paclitaxel have now become the first-line options for OSCC patients.Nevertheless,most OSCC patients eventually acquire drug resistance,leading to poor prognosis.With the discovery and identification of non-coding RNAs(ncRNAs),the functions of dysregulated ncRNAs in OSCC development and drug resistance are gradually being widely recognized.The mechanisms of drug resistance of OSCC are intricate and involve drug efflux,epithelial-mesenchymal transition,DNA damage repair,and autophagy.At present,strategies to explore the reversal of drug resistance of OSCC need to be urgently developed.Nano-delivery and self-cellular drug delivery platforms are considered as effective strategies to overcome drug resistance due to their tumor targeting,controlled release,and consistent pharmacokinetic profiles.In particular,the combined application of new technologies(including CRISPR systems)opened up new horizons for the treatment of drug resistance of OSCC.Hence,this review explored emerging regulatory functions of ncRNAs in drug resistance of OSCC,elucidated multiple ncRNA-meditated mechanisms of drug resistance of OSCC,and discussed the potential value of drug delivery platforms using nanoparticles and self-cells as carriers in drug resistance of OSCC.Xiang Meng Qiu-Yue Lou Wen-Ying Yang Yue-Rong Wang Ran Chen Lu Wang Tao Xu Lei Zhang 2021Cancer Communications2021,41,10:8
12Tunable and scalable broadband metamaterial absorber involving VO2-based phase transition显示文摘Optical absorbers with dynamic tuning features are able to flexibly control the absorption performance, which offers a good platform for realizing optical switching, filtering, modulating, etc. Here, we propose a thermally tunable broadband absorber applying a patterned plasmonic metasurface with thermo-chromic vanadium dioxide (VO2) spacers. An actively tunable absorption bandwidth and peak resonant wavelength in the region from the near-to mid-infrared (NMIR) are simultaneously achieved with the insulating.metallic phase transition ofVO2·Moreover, the scalable unit cell,which is composed of multi-width sub-cells, provides a new freedom to further manipulate (i.e., broaden or narrow) the absorption bandwidth while maintaining a high relative absorption bandwidth and efficient absorbance at the same time. For both transverse-electric and transverse-magnetic polarizations, the proposed nanostructure exhibits a high absorption over a wide angular range up to 60°.This method holds a promising potential for versatile utilizations in optical integrated devices,NMIR photodetection, thermal emitters, smart temperature control systems,and so fbrth.Lei Lei Fei Lou Keyu Tao Haixuan Huang Xin Cheng Ping Xu 2019Photonics Research2019,7,7:8
13Cenozoic tectonic and sedimentary evolution of southern Qaidam Basin, NE Tibetan Plateau and its implication for the rejuvenation of Eastern Kunlun Mountains显示文摘The Eastern Kunlun Mountains play an important role in the growth and eastward extrusion of the Tibetan Plateau. Tectonic and sedimentary study of the Cenozoic Qaidam Basin, especially the southern part, provides key evidence for understanding their evolution. Here we present evidence including isopach maps, seismic sections and sedimentary analysis of single well to illustrate the sedimentary development of the basin and the structural features of its southern margin. The Qaidam Basin extended across Qiman Tagh-Eastern Kunlun Mountains in the early Cenozoic and withdrew northward at ca. 35.5 Ma, and then buckled as an EW striking elliptical depression since ca. 14.9 Ma, with the main depocenter migrating eastward. Our results support the view that the Kumukol and Hoh Xil basins joined the Qaidam Basin in the early Cenozoic time and we propose the Eastern Kunlun Mountains uplifted in the mid-Miocene.MAO LiGuang XIAO AnCheng WU Lei LI BenLiang WANG LiQun LOU QianQian DONG YouPu QIN SuHua 2014Science China Earth Sciences2014,57,11:7
14Machine Learning−based Weather Support for the 2022 Winter Olympics显示文摘1.A key support for the 2022 Winter Olympics The XXIV Olympic Winter Games are scheduled to take place from 4 to 22 February 2022,followed by the Paralympic Games from 4 to 13 March,in Beijing and towns in the neighboring Hebei Province,China.Weather plays an extremely important role in the outcome of the games(Chen et al.,2018).It can not only cause a difference between a medal or not,but affect the safety of athletes.Success of the Winter Olympics will greatly depend on weather conditions at the outdoor competition venues,dealing with many weather elements including the snow surface temperature,apparent temperature,gust wind speed,snow,visibility,etc.To ensure that the scheduled games go smoothly,it is imperative to have hourly or even every 10-minutely forecasts as well as updated weather-related risk assessments at the venues for the next 240 hours.So far,the Beijing/Hebei Meteorological Observatory has already started intelligent weather forecasting at 3-km resolution based on the results of numerical weather prediction(NWP)models.However,these experiments have suggested that the current forecasting techniques are incapable of capturing the complex mountain weather variations around some venues.The forecasting capability of NWP is constrained partly by limited knowledge of the local weather mechanisms.Jiangjiang XIA Haochen LI Yanyan KANG Chen YU Lei JI Lve WU Xiao LOU Guangxiang ZHU Zaiwen Wang Zhongwei YAN Lizhi WANG Jiang ZHU Pingwen ZHANG Min CHEN Yingxin ZHANG Lihao GAO Jiarui HAN 2020Advances in Atmospheric Sciences2020,37,9:6
15Activation of Toll-like receptors signaling in non-small cell lung cancer cell line induced by tumor-associated macrophages显示文摘Background:Inflammation is often linked with the progress and poor outcome of lung cancer.The understanding of the relationship between tumor-associated macrophages(TAMs) and lung cancer cells involves in the underlying mechanism of inflammatory cytokine production.Toll-like receptors(TLRs) are engaged in promoting the production of pro-inflammatory cytokines and play an important role in tumor immunology.Methods:To investigate the mechanisms by which TAMs influence the production of pro-inflammatory cytokines in lung cancer cells,we established an in vitro coculture system using TAMs and human nonsmall cell lung cancer(NSCLC) cell line SPC-A1.Levels of interleukin(IL)-1β,IL-6 and IL-8 in SPC-A1 were evaluated by RT-PCR and cytometric bead array assay after being cocultured with TAMs.Expression changes of TLRs and TLRs signaling pathway proteins in SPC-A1 were further confirmed by RT-PCR and western blot.The level changes of IL-1β,IL-6 and IL-8 in SPC-A1 were also detected after the stimulation of TLRs agonists.Results:We found that the phenotype markers of TAMs were highly expressed after stimulating human monocyte cell line THP-1 by phorbol-12-myristate-13-acetate(PMA).Higher mRNA and supernate secretion levels of IL-1β,IL-6 and IL-8 were detected in SPC-A1 after being cocultured with TAMs.We also found that TLR1,TLR6 and TLR7 were up-regulated in SPC-A1 in the coculture system with TAMs.Meanwhile,TLRs signaling pathway proteins were also significantly activated.Moreover,pre-treatment with agonist ligands for TLR1,TLR6 and TLR7 could dramatically promote inductions of IL-1β,IL-6 and IL-8.Conclusions:These findings demonstrated that TAMs may enhance IL-1β,IL-6 and IL-8 expressions via TLRs signaling pathway.We conclude that TAMs contribute to maintain the inflammation microenvironment and ultimately promote the development and progression of lung cancer.Xing Ke Meng Wu Jianfang Lou Shuping Zhang Peijun Huang Ruihong Sun Lei Huang Erfu Xie Fang Wang Bing Gu 2015Chinese Journal of Cancer Research2015,27,2:6
16Elimination of misrun and gas hole defects of investment casting TiAl alloy turbocharger based on numerical simulation and experimental study显示文摘Casting technology of thin-wall TiAl alloy turbochargers was studied by investment casting and numerical simulation.Misruns and gas holes were the main defects observed in preliminary work due to the poor fluidity of alloy,and to gas entrapment.In order to eliminate these defects,cast parameters,such as centrifugal rotation rate and mould preheating temperature,were optimized by numerical simulation,meanwhile,the structure of the shell mould was optimized to improve the filling capacity of TiAl alloy.Pouring experiments were carried out by vacuum induction melting furnace equipped with a water-cooled copper crucible based on the above optimization.The quality of the TiAl alloy casting was analyzed by fluorescent penetrant inspection and X-ray detection.The results show that a centrifugal rotation rate of 200 rpm,mould preheating temperature of 600°C,shell preparation through organic fiber addition can dramatically improve the mould filling capacity,and integrated turbochargers were finally prepared.Jun Zhao Zhi-yong Zhang Shi-bing Liu Kun Shi Chun-ling Bao Zhao-sheng Ning Ping Yan Lei Wang Yan-chun Lou 2020China Foundry2020,17,1:6
17An AIEgens and exonuclease Ⅲ aided quadratic amplification assay for detecting and cellular imaging of telomerase activity显示文摘Monitoring telomerase activity with high sensitive and reliable is of great importance to cancer analysis.In this paper, we report a sensitive and facile method to detect telomerase activity using AIEgens modified probe(TPE-Py-DNA) as a fluorescence reporter and exonuclease Ⅲ(Exo Ⅲ) as a signal amplifier.With the aid of telomerase, repeat units(TTAGGG)n are extended from the end of template substrate oligonucleotides(TS primer) that form duplex DNAs with TPE-Py-DNA. Then, Exo Ⅲ catalyzes the digestion of duplex DNAs, liberating elongation product and releasing hydrophobic TPE-Py. The released hydrophobic TPE-Py aggregate together and produce a telomerase-activity-related fluorescence signal.The liberated product hybridizes with another TPE-Py-DNA probe, starting the second cycle. Finally,we obtain the target-to-signal amplification ratio of 1:N^2. This strategy exhibits good performance for detecting clinical urine samples(distinguishing 15 cancer patients' samples from 8 healthy ones) and checking intracellular telomerase activity(differentiating cell lines including He La, MDA-MB-231,MCF-7, A375, HLF and MRC-5 from the cells pretreated with telomerase-related drug), which shows its potential in clinical diagnosis as well as therapeutic monitoring of cancer.Xuehong Min Lei Xia Yuan Zhuang Xudong Wang Jie Du Xiaojin Zhang Xiaoding Lou Fan Xia 2017Science Bulletin2017,62,14:5
18SHR-A1403, a novel c-Met antibody-drug conjugate, exerts encouraging anti-tumor activity in c-Met-overexpressing models显示文摘Emerging evidence demonstrates that a c-Met antibody-drug conjugate (ADC) has superior ef?cacy and safety pro?les compared with those of currently available small molecules or antibody inhibitors for the treatment of c-Met-overexpressing cancers. Here we described both the in vitro and in vivo ef?cacies of SHR-A1403, a novel c-Met ADC composed of a humanized IgG2 monoclonal antibody against c-Met conjugated to a novel cytotoxic microtubule inhibitor. SHR-A1403 showed high af?nity to c-Met proteins derived from human or monkey and potent inhibitory effects in cancer cell lines with high c-Met protein expression. In mice bearing tumors derived from cancer cell lines or patient HCC tissues with con?rmed c-Met overexpression, SHR-A1403 showed excellent anti-tumor ef?cacy. Antibody binding with c-Met contributed to SHR-A1403 endocytosis;the subsequent translocation to lysosomes and cytotoxicity of the released toxin are speculated to be predominant mechanisms underlying the anti-tumor activity of SHR-A1403. In conclusion, SHR-A1403 showed signi?cant anti-tumor activity in cancer cell lines, xenograft mouse models and an HCC PDX model, which all have high c-Met levels. These data provide references for SHR-A1403 as a potential therapy for the treatment of cancers with c-Met overexpression.Chang-yong Yang Lei Wang Xing Sun Mi Tang Hai-tian Quan Lian-shan Zhang Li-guang Lou Shao-hua Gou 2019Acta Pharmacologica Sinica2019,40,7:5
19Grade classification of neuroepithelial tumors using high-resolution magic-angle spinning proton nuclear magnetic resonance spectroscopy and pattern recognition显示文摘Clinical data have shown that survival rates vary considerably among brain tumor patients,according to the type and grade of the tumor.Metabolite profiles of intact tumor tissues measured with high-resolution magic-angle spinning proton nuclear magnetic resonance spectroscopy (HRMAS 1H NMRS) can provide important information on tumor biology and metabolism.These metabolic fingerprints can then be used for tumor classification and grading,with great potential value for tumor diagnosis.We studied the metabolic characteristics of 30 neuroepithelial tumor biopsies,including two astrocytomas (grade I),12 astrocytomas (grade II),eight anaplastic astrocytomas (grade III),three glioblastomas (grade IV) and five medulloblastomas (grade IV) from 30 patients using HRMAS 1H NMRS.The results were correlated with pathological features using multivariate data analysis,including principal component analysis (PCA).There were significant differences in the levels of N-acetyl-aspartate (NAA),creatine,myo-inositol,glycine and lactate between tumors of different grades (P<0.05).There were also significant differences in the ratios of NAA/creatine,lactate/creatine,myo-inositol/creatine,glycine/creatine,scyllo-inositol/creatine and alanine/creatine (P<0.05).A soft independent modeling of class analogy model produced a predictive accuracy of 87% for high-grade (grade III-IV) brain tumors with a sensitivity of 87% and a specificity of 93%.HRMAS 1H NMR spectroscopy in conjunction with pattern recognition thus provides a potentially useful tool for the rapid and accurate classification of human brain tumor grades.CHEN WenXue LOU HaiYan ZHANG HongPing NIE Xiu LAN WenXian YANG YongXia XIANG Yun QI JianPin LEI Hao TANG HuiRu CHEN FenEr DENG Feng 2011Science China(Life Sciences)2011,54,7:5
20Synthesis of large-scale atomic-layer SnS2 through chemical vapor deposition显示文摘因为他们的 ultrathin 厚度和潜在的应用,金属 dichalcogenides 的二维的层在电子学和光电子吸引了许多注意。有 ~ 的乐队差距的单层 SnS 2, 2.6 eV,有用硫的二原子层和锡的一原子层做的一个八面的格子。到日期为止,在那里被限制了作为一个半导体在大规模、高质量的 SnS 2 的生长上报导原子层和他们的性质的调查。这里,我们与一种大水晶尺寸和一致性报导原子层的 SnS 2 的化学蒸汽免职(CVD ) 生长。另外,层的数字能被改变生长时间从单层改变到很少层并且到体积。扫描传播电子显微镜学被用来分析原子结构并且表明叠不同的层的 poly 类型的 2H。结果的 SnS 2 晶体象 150% 一样高与外部量效率被用作一个光电探测器,建议为 optoelectronic 应用的诺言。Gonglan Ye Yongji Gong Sidong Lei Yongmin He Bo Li Xiang Zhang Zehua Jin Liangliang Dong Jun Lou Robert Vajtai Wu Zhou Pulickel M. Ajayan 2017Nano Research2017,10,7:4
返回顶部 每页显示:
共6页 首页 上一页 第1页 下一页 末页 /6 跳转

网站首页 | 关于我们 | 联系我们 | 产品服务 | 客服中心 | 广告服务 | 版权声明 | 网站联盟 | 友情链接 | 售卡网点

版权所有© 渝B2-20050021-1 渝公网安备 50019002500403号 违法和不良信息举报中心

互联网出版许可证 新出网证(渝)字10号 全国400电话 - 免长途话费