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1.
BackgroundStudies related to infectivity status of insect vectors are seen as necessities in understanding the epidemiology of vector-borne diseases and planning effective control measures. This study assessed the infectivity ofSimulium damnosum s.l. around Owena River as well as evaluated therapeutic coverage of Ivermectin distribution in the area.MethodHuman landing sampling method was used to collect adult flies on human attractants from 07:00 to 18:00 for two consecutive days a month for three months (July 2016 - September 2016). Parity assessment was conducted to determine the age of fly populations. Parous flies were further dissected to detect the presence or absence ofOnchocerca larvae. Biting rates and transmission potentials were calculated using standard methods. A quantitative survey was carried out to determine the therapeutic coverage and compliance to ivermectin treatment for the control of Onchocerciasis in the study area using standard household coverage questionnaires.ResultsA total of 914 adult female flies were collected during the study period. The daily biting rate (DBR) varied from 146 fly per man day (FMD) in July to 162.5 FMD in August. The monthly biting rate (MBR) was lowest in September (2170 bites per man per month) but highest in August (3358.3 bites per man per month). MBD ranged from 13.23 fly per man hour (FMH) in July to 14.77 FMH in August. The results indicated that the majority of the flies collected at the sampling points were nulliparous [685 (74.95%)] while others were parous [229 (25.05%)]. The biting activity of the flies showed a marked decrease in population in August compared to July which later increased in September. Infection rates varied from 2 (0.7%) in July to 7 (2.2%) in August while the infectivity rate during the study ranged from zero (July and September) to 3 (1.0%) in August.ConclusionDespite the years of treatment of onchocerciasis in Owena community, there were still some infective flies capable of transmitting O. volvolus. This could be due to the low rate of therapeutic coverage as a result of non-compliance in the community for various reasons earlier stated.  相似文献   
2.
目的研究新型冠状病毒(新冠病毒)感染者末次核酸阴性前后密切接触者(密接)的感染率, 评估动态核酸检测结果在判断新冠病毒感染者传染性中的作用。方法采用回顾性队列研究的方法, 收集新冠病毒感染者的动态核酸检测结果。选择新冠病毒感染者在首次核酸检测阳性前有核酸阴性结果者为研究对象, 对感染者的密接以及密接的密接(次密接)进行持续隔离医学观察, 评估密接和次密接的发病风险。结果共纳入宁波市2起本土疫情的89例新冠病毒感染者, 均为确诊病例。追踪调查了5 609名密接, 密接的总感染率为0.20%。感染者末次核酸阴性前的密接无感染, 末次核酸阴性后的密接感染率为1.33%, 且均为与指示病例共同居住生活者。感染者涉及的所有次密接均未感染。结论新冠病毒感染者末次核酸阴性前无传染性, 末次核酸阴性后开始具有传染性。  相似文献   
3.
Huang X  Jin W  Hu K  Luo S  Du T  Griffin GE  Shattock RJ  Hu Q 《Virology》2012,423(1):97-106
Glycosylation plays important roles in gp120 structure and HIV-1 immune evasion. In the current study, we introduced deglycosylations into the 24 N-linked glycosylation sites of a R5 env MWS2 cloned from semen and systematically analyzed the impact on infectivity, antigenicity, immunogenicity and sensitivity to entry inhibitors. We found that mutants N156-T158A, N197-S199A, N262-S264A and N410-T412A conferred decreased infectivity and enhanced sensitivity to a series of antibodies and entry inhibitors. When mice were immunized with the DNA of wild-type or mutated gp160, gp140 or gp120; N156-T158A, N262-S264A and N410-T412A were more effective in inducing neutralizing activity against wild-type MWS2 as well as heterologous IIIB and CH811 Envs. In general, gp160 and gp140 induced higher neutralizing activity compared with gp120. Our study demonstrates for the first time that removal of individual glycan N156, N262 or N410 proximal to CD4-binding region impairs viral infectivity and results in enhanced capability to induce neutralizing activity.  相似文献   
4.
目的观察食用醋或酱油对旋毛虫肌幼虫感染性和生殖力的影响。方法140只雄性昆明小鼠随机均分为14组,分别喂饲经食用醋(总酸浓度4.5%,pH3.05)、食用酱油(含19.3%NaCl)和生理盐水浸泡不同时间的含有300条旋毛虫肌幼虫的小鼠肌肉(重约0.02g),于喂饲后第7天和第42天每组各剖杀5只小鼠,分别观察肠道成虫、肌幼虫的数量和生殖力指数(RCI)。结果小鼠喂饲经食用醋处理3、6、12和24h的旋毛虫肌幼虫后,其肠道成虫数分别为77、41、0和0条,RCI分别为52.48、18.45、0和0,均显著低于生理盐水对照组肠道成虫数(分别为121、121、116和101条)和RCI(分别为159.10、124.56、73.63和42.17)(P0.05)。小鼠喂饲经食用酱油处理12、24、36和48h的旋毛虫肌幼虫后,肠道成虫数(分别为79、39、3和0条)和RCI(分别为48.75、20.80、1.87和0)亦均明显低于对照组(116、101、95和89条,73.63、42.17、21.53和4.13)(P0.05)。感染小鼠的肠道成虫数和RCI均随醋或酱油处理时间的延长而降低(P0.05)。结论含旋毛虫肌幼虫的肌肉经食用醋或酱油处理后,肌幼虫的感染力和生殖力均明显下降。  相似文献   
5.
Ziming Weng 《Virology》2009,393(2):346-354
The genome of Red clover necrotic mosaic virus (RCNMV) consists of positive-sense, single-stranded RNA-1 and RNA-2. The 29 nucleotides at the 3′ termini of both RNAs are nearly identical and are predicted to form a stable stem-loop (SL) structure, which is required for RCNMV RNA replication. Here we performed a systematic mutagenesis of the RNA-2 3′ SL to identify the nucleotides critical for replication. Infectivity and RNA replication assays indicated that the secondary structure of the 3′ SL and its loop sequence UAUAA were required for RNA replication. Single-nucleotide substitution analyses of the loop further pinpointed three discontinuous nucleotides (L1U, L2A, and L4A) that were vital for RNA replication. A 3-D model of the 3′ SL predicted the existence of a pocket formed by these three nucleotides that could be involved in RNA-protein interaction. The functional groups of the bases participating in this interaction at these positions are discussed.  相似文献   
6.
来自不同疟疾疫区——长沙、上海、郑州、武汉四地区的中华按蚊,分别以羊膜饲血法感染湖南慈利或湖北沔阳两地区的间日疟原虫,交叉对比其易感性。七次实验共解剖饲血蚊541只。实验结果显示:以腺感染率和阳性腺指数为主要指标,四地区中华按蚊对间日疟原虫的易感性基本相似:两地区间日疟原虫对中华按蚊的感染力也大致相同。并讨论了可能影响人工感染率的几个因素。  相似文献   
7.
The purpose of our entomological survey was to estimate mosquito biodiversity, infectivity rates and insecticide resistance levels in Anopheles species in four study sites in a mining area with high malaria transmission in southeastern Guinea. Anopheles gambiae s.l. (77%) was the most common Anopheles collected followed by An. funestus (20%). The specimens of the An. gambiae complex were predominantly An. gambiae S form (97.6%) with 1.4% of An. gambiae M form found in Kérouané only, and 1% of An. arabiensis which was present in all four study sites. Anopheles gambiae S form and An. funestus were found to be infected with Plasmodium falciparum, with infectivity rates of 4.1% and 4.4% and inoculation rates of 0.60 and 0.19 infected bite/person/night, respectively. In addition, a high level (79%) of the knockdown resistance (kdr) L1014F mutation was reported in the populations of An. gambiae S form. The high malaria transmission that occurs in the prospected area of Guinea requires a long-term vector control programme. However, such a control programme will have to consider the presence of the kdr gene at a surprisingly high level within the dominant vector, which could reduce the expected impact of vector control.  相似文献   
8.
目的 探讨东洞庭湖及邻近长江水域在涨水期不同月份的水位下 ,血吸虫病易感地带水体感染性的变化。 方法 在东洞庭湖及长江水域各设 1个观察现场 ,采用小白鼠作为水体感染实验动物。 1999年 5月至 8月分别采用一批小白鼠连续感染 3 d,每天 2 h。 结果 东洞庭湖水域在 5、6、7、8月涨水期小白鼠感染率分别为 80 .49% ,10 0 % ,79.49% ,14.63 % ;长江水域感染率分别为 15 .0 0 % ,15 .3 8% ,2 8.2 1% ,7.5 0 %。 结论 在涨水期东洞庭湖水域哨鼠感染率明显高于长江水域 ( P<0 .0 1) ;长江水域在高水位期感染率较高  相似文献   
9.
目的了解曼氏血吸虫吡喹酮抗性株对终宿主致病作用的强弱.方法采用浸尾法以200尾蚴/鼠逐只感染远交系CD1鼠,感染57 d后采集鼠粪便计数虫卵;78 d后剖杀鼠收集成虫计数并摘取肝脏和肠做组织虫卵计数;95 d后取肝组织,切片、染色测量虫卵肉芽肿面积和周长.比较抗性株与敏感株对终宿主的易感性、产卵量和肝虫卵肉芽肿面积.结果抗性株和敏感株感染鼠成虫回收数为22.5条/鼠和21.8条/鼠;抗性株感染鼠粪便虫卵数为68.6只/100 mg,敏感株为31.7只/100 mg,两者间差异有非常显著性;感染第78天,抗性株组织虫卵数为8 364只/对成虫,敏感株为4 665只/对成虫,两者间差异有非常显著性;敏感株产于肝和肠组织虫卵数为1 540只/对成虫和3 124只/对成虫,抗性株分别为4 297只/对成虫和3 887只/对成虫;抗性株和敏感株感染鼠肝虫卵肉芽肿面积分别为392 236μm2和523 263μm2,周长分别为2 385μm和2 882 μm,两者间差异均无显著性.结论抗性株在粪便与组织中产卵量均高于敏感株,故抗性株对终宿主的致病作用强于敏感株.  相似文献   
10.
目的 探讨感染性脊柱炎在低场强MR的信号特征及其诊断与鉴别诊断价值。方法收集42例感染性脊柱炎的低场强MR图像,分析其信号特征。结果42例病变中39例累及多椎体,3例累及单椎体。42例中35例病变呈不均匀长T1、长T2信号为主,在T2、W1上可见条片状低信号,7例呈均匀长T1、长T2信号;在STIR及TSHIRT脂肪抑制序列上所有病变均呈不均匀高信号。静脉注射Gd-DTPA后所有病灶呈轻至中度不均匀强化,35例脊柱结核中有20例表现为边缘强化,29例脊柱结核及3例真菌感染的椎间盘均有不同程度的破坏。26例惟体结核存在寒性脓疡。结论低场强MRI可以发现感染性脊柱炎中椎体及其周围组织受累情况,结合临床,部分病例可作出定性诊断。  相似文献   
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