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   139篇
  免费   31篇
  国内免费   8篇
  2024年   1篇
  2023年   6篇
  2022年   12篇
  2021年   7篇
  2020年   6篇
  2019年   8篇
  2018年   6篇
  2017年   5篇
  2016年   11篇
  2015年   8篇
  2014年   11篇
  2013年   12篇
  2012年   9篇
  2011年   4篇
  2010年   7篇
  2009年   4篇
  2008年   11篇
  2007年   8篇
  2006年   7篇
  2005年   6篇
  2004年   6篇
  2003年   1篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
  1999年   2篇
  1998年   1篇
  1995年   3篇
  1992年   1篇
  1991年   2篇
  1989年   2篇
  1988年   1篇
  1979年   1篇
  1978年   1篇
  1974年   1篇
  1972年   1篇
排序方式: 共有178条查询结果,搜索用时 531 毫秒
71.
摘要 目的:分析健康体检人群幽门螺杆菌(Hp)感染的影响因素,并探讨Hp感染对糖脂代谢和血清胃蛋白酶原Ⅰ(PGⅠ)、胃蛋白酶原Ⅱ(PGⅡ)和胃泌素17(G-17)的影响。方法:选择2017年1月~2019年12月期间在我院进行Hp检查的117例健康体检者进行问卷调查,分析其Hp感染情况,并应用多因素Logistic回归分析健康体检人群Hp感染的影响因素。将体检者分为Hp阳性组和Hp阴性组,对比两组血糖、血脂指标以及血清PGⅠ、PGⅡ、G-17水平。结果:117例受试体检者中Hp阳性49例,阳性率为41.88%,其中男性感染率为50.85%(30/59),显著高于女性感染率的32.76%(19/58)(x2=10.537,P=0.001)。不同年龄体检者Hp阳性率比较差异无统计学意义(P>0.05)。不同学历体检者Hp阳性率比较差异无统计学意义(P>0.05)。多因素Logistic回归分析结果显示,饮酒、经常喝生水、经常在外就餐、经常吃辛辣食物、有家人Hp感染史是健康体检人群Hp感染的危险因素(P<0.05)。Hp阳性组的空腹血糖(FPG)、甘油三脂(TG)、总胆固醇(TC)、低密度脂蛋白(LDL-C)水平均高于Hp阴性组,而高密度脂蛋白(HDL-C)水平则低于Hp阴性组(P<0.05)。Hp阳性组的血清PGⅠ、PGⅡ、G-17水平均高于Hp阴性组(P<0.05)。结论:饮酒、经常喝生水、经常在外就餐、经常吃辛辣食物、有家人Hp感染史是健康体检人群Hp感染的危险因素,糖脂代谢及血清PGⅠ、PGⅡ、G-17水平变化与Hp感染有关。  相似文献   
72.
摘要 目的:分析健康体检人群非酒精性脂肪肝病(NAFLD)的影响因素,并观察NAFLD患者肾功能和亚临床动脉粥样硬化相关指标的变化情况。方法:以2019年5月至2022年8月期间到解放军总医院第二医学中心进行普通健康体检者1398例为研究对象,其中确诊为NAFLD纳为病例组,其余纳为对照组。以单因素和多因素logistic回归分析方法分析健康体检人群NAFLD的影响因素,并观察NAFLD患者肾功能[血肌酐(Scr)、尿素氮(BUN)、血尿酸(UA)、肾功能受损发生率]和亚临床动脉粥样硬化相关指标[内膜中层厚度(cIMT)、颈总动脉僵硬度指数(β)、血管压力-应变弹性系数(Ep)、单点脉搏波传导速度(PWVβ)]的变化情况。结果:1398例研究对象中,完成全部调查的1372例,完成率为98.14%(1372/1398)。其中确诊为NAFLD的有184例,纳为病例组,其余1188例纳为对照组。检出率为13.41%(184/1372)。单因素分析结果显示,NAFLD的发病与性别、体重指数、文化程度、工作性质、居住地、运动锻炼情况、喜好荤食、喜好甜食、高血压史、高血脂史、糖尿病史、NAFLD家族史、TG、空腹血糖、HDL-C、LDL-C、TC有关(P<0.05)。多因素Logistic回归分析模型结果显示,性别为男、体重指数偏高、喜好荤食、喜好甜食、TG偏高、空腹血糖偏高、LDL-C偏高、TC偏高、HDL-C偏低是NAFLD发生的危险因素,而运动锻炼情况≥30 min/d是NAFLD发生的保护因素(P<0.05)。病例组的Scr、BUN、UA、肾功能受损发生率高于对照组(P<0.05)。病例组的cIMT、β、Ep、PWVβ均高于对照组(P<0.05)。结论:性别为男、体重指数偏高、喜好荤食、喜好甜食、TG偏高、空腹血糖偏高、LDL-C偏高、TC偏高、HDL-C偏低是NAFLD发生的危险因素,运动锻炼情况≥30 min/d是NAFLD发生的保护因素。NAFLD患者存在肾功能损伤和亚临床动脉粥样硬化风险,值得引起临床重视。  相似文献   
73.
A combination of methods is described to identify and reconstruct corpuscular and non-corpuscular sensory endings of group II and group III nerve fibers following functional examination by electrophysiology. Afferent units activated by electrical stimulation of the medial articular nerve of the cat's knee were analyzed by single fiber recordings and characterized by their responsiveness to mechanical stimuli. The receptive fields of the units were closely demarcated by fine needles when the responses elicited by insertion of the needles were being recorded. After fixation, the tissue around the demarcated field was dissected and histologically processed. Series of semithin sections were cut from the embedded tissue blocks containing the receptive fields. Corpuscular endings of group II fibers and peripheral myelinated group III nerve fibers, presumably corresponding to the characterized units, were identified by light microscopy of semithin sections and localized within the demarcated area. Non-corpuscular endings were identified by electron microscopy of ultrathin sections cut in alternation with, or after re-embedding of, semithin sections. Morphometric analysis of ultrathin section series allowed the measurement of parameters such as the mean axon diameter and the organelle content of the sensory endings. The methods described are appropriate for collecting data that correlate the structural and functional characteristics of sensory endings in deep tissues.  相似文献   
74.
Per Onsberg 《Mycopathologia》1979,67(3):153-155
The dermatophytes Epidermophyton floccosum, Microsporum canis, Trichophyton mentagrophytes var. interdigitale, T. rubrum, and T. verrucosum were compared with respect to the direct microscopic examination of a clinical material and the number of colonies obtained by culture.It was found that the results of microscopy as well as of culture depended to a marked extent upon which species were the cause of the mycosis.The extremes were E. floccosum and T. mentagrophytes var. interdigitale which showed 7.5 % and 32.5 % isolates with negative microscopic findings and 45.5 % and 5.0 % isolates with 10 colonies.  相似文献   
75.
Somatic embryogenesis and organogenesis in Lilium pumilum were successfully regulated by picloram, α-naphthaleneacetic acid (NAA), and 6-benzyladenine (BA). In organogenesis, the highest shoot regeneration frequency (92.5%) was obtained directly from bulb scales on Murashige and Skoog (MS) medium containing 2.0 mg L?1 BA and 0.2 mg L?1 NAA, while organogenic callus (OC) formed from leaves on MS medium supplemented with 1.0 mg L?1 BA and 0.5 mg L?1 NAA. Following subculture, 76.7% of OC regenerated shoots. In somatic embryogenesis, the combination of picloram and NAA increased the amount of embryogenic callus (EC) that formed with a maximum on 90.7% of all explants which formed 11 somatic embryos (SEs) per explant. Differences between EC and OC in cellular morphology and cell differentiation fate were easily observed. SEs initially formed via an exogenous or an endogenous origin. The appearance of a protoderm in heart-shaped SE and the bipolar shoot–root development in oval-shaped SE indicated true somatic embryogenesis. This protocol provides a new and detailed regulation and histological examination of regeneration pattern in L. pumilum.  相似文献   
76.
A method is presented for histological examination of undecalcified ground sections of tooth roots affected with periodontal disease. The roots were placed in Karnovsky's fixative overnight, postfixed in 2% buffered osmic acid, and dehydrated in an ascending series of ethanol. The specimens were then infiltrated with propylene-oxide and Epon-Araldite resin, embedded in Epon-Araldite, and sections were prepared using a cutting and grinding system. The resulting ground sections were 8-12 μm thick. The sections were allowed to air dry at room temperature. When thoroughly dried, a coverglass was applied using resinous mounting medium DPX. The specimens were examined by phase-contrast microscopy. The method is useful for simultaneous examination of mineralized dental tissue and bacterial morphotypes covering the root surface of teeth involved with periodontal disease.  相似文献   
77.
石质建筑暴露在自然环境中不可避免地遭到各种因素的影响,其中由细菌、真菌、藻类、地衣和苔藓等引起的生物风化问题普遍存在,生物风化的长期累积效应会导致石质建筑在物理结构、化学性质和美学特征等方面发生不可逆的变化和损坏。因此,运用不同方法来减少生物对石质建筑的侵蚀是非常必要的。本文根据典型案例整理归纳了目前研究中生物风化治理的传统方法(包括热处理、激光和紫外线辐照、施用杀菌剂等)和几种新兴技术(包括物理方法和化学方法协同作用、植物提取物和纳米材料作为杀菌剂等),并对其优缺点及适用性进行了评述。本文还论述了石质建筑生物风化的防护对策和防治效果的检测方法,并对未来研究方向进行了展望,旨在为石质建筑的生物风化防治研究提供方法借鉴和参考。  相似文献   
78.
The objective of this study was to determine whether continuous, long-term, fenceline exposure of prepubertal beef bulls to cycling beef females reduced age at puberty and influenced the percentage of bulls that passed an initial breeding soundness examination (BSE). Bulls (Angus, n = 37; Simmental, n = 22; Hereford, n = 10; Simmental × Angus, n = 8) at an average age of 202 ± 21.5 days were given either continuous fenceline and visual exposure to cycling females (exposed, n = 41) or no exposure (control, n = 36). Estrus was induced in cycling beef females so at least three females were in standing estrus each week during the 182 days of exposure to bulls. Scrotal circumference (SC), body weight, and blood samples were collected every 28 days. When bulls had SC of 26 cm or more, semen samples were obtained monthly via electroejaculation until puberty was achieved (≥50 × 106 sperm/mL with at least 10% progressive motility). Behavioral observations were conducted twice monthly: once when females were in estrus and once during diestrus. Homosexual mounting, flehmen responses, and number of times near penned females were recorded for each observation period. Breeding soundness examinations were conducted when the average age of bulls was 364 ± 21.5 days. Normal sperm morphology of at least 70% and sperm motility of at least 30% were required to pass the BSE. Age, body weight, and SC at puberty did not differ between exposed and control bulls (320 ± 28 and 311 ± 29 days; 466.2 ± 12.2 and 437.7 ± 13.5 kg; and 34.4 ± 2.5 and 34.9 ± 2.5 cm, respectively). Percentage of bulls passing their initial BSE did not differ between treatments (exposed, 87.8%; control, 75.0%). Treatment, month, and female estrous stage interacted (P = 0.05) to affect the number of mount attempts and flehmen responses. Exposed bulls entered the cow area more times (P < 0.001) during estrus than diestrus in Months 1, 2, and 3. We concluded that bulls given continuous, long-term, fenceline exposure to cycling beef females do not have enhanced sexual development.  相似文献   
79.
Cryopreservation of Human Ovarian Tissue   总被引:2,自引:0,他引:2  
New and often aggressive treatment schemes allow the successful healing of many young patients with cancer, but the price the young women have to pay is high: many of them lose ovarian function and fertility. Due to the improved long-term survival of adolescents and young women with malignancies undergoing gonadotoxic chemotherapy, preservation of future fertility has been the focus of recent ubiquitarian interest. A feasible solution is the cryopreservation of ovarian tissue. Ovarian tissue, after thawing, can be used in three different ways: 1. grafted into its normal site (orthotopic); 2. grafted into a site other than its normal position (heterotopic), necessitating recourse to in vitro fertilization (IVF); 3. grown and in vitro matured in order to obtain metaphase II oocytes for an IVF program. It is believed that protein supplementation, in cryopreservation solution, is essential for improving ovarian tissue cryopreservation. The aim of this study was to evaluate the ultrastructural appearance of human ovarian tissue cryopreserved in 1.5 M 1,2 propanediol (PROH), 0.2 M sucrose using different protein sources: fetal calf serum (FCS), plasmanate or syntetic serum substitute (SSS). Fresh and frozen/thawed ovarian tissues were compared by transmission electron microscope (TEM), to evaluate the appearance of stromal and follicle cells as affected by different protein sources. Our data indicate that FCS is a better protein support for ovarian tissue cryopreservation when compared to SSS or Plasmanate. In addition the follicles are more resistant to the cryopreservation with respect to stroma.  相似文献   
80.
目的 分析超声检查服务系统的运行规律,为超声检查资源的优化配置提供科学依据。方法 采用排队论的理论与方法,随机测量某三级综合医院的超声检查服务时间及患者到达时间,计算服务强度等运行指标。结果 当前超声检查上午的服务强度过高(>110%),下午各队列的服务强度在77%~85%,服务流程不合理。通过改变预约模式,可有效地提高系统的运行效率。结论 应用排队论的理论与方法评价超声检查服务流程效率合理可行,值得推广。  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