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   266篇
  免费   67篇
  2024年   2篇
  2023年   13篇
  2022年   11篇
  2021年   26篇
  2020年   27篇
  2019年   23篇
  2018年   11篇
  2017年   10篇
  2016年   9篇
  2015年   15篇
  2014年   23篇
  2013年   25篇
  2012年   13篇
  2011年   15篇
  2010年   8篇
  2009年   7篇
  2008年   11篇
  2007年   17篇
  2006年   6篇
  2005年   9篇
  2004年   6篇
  2003年   8篇
  2002年   4篇
  2001年   2篇
  2000年   2篇
  1998年   4篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1993年   3篇
  1992年   2篇
  1991年   2篇
  1990年   4篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
排序方式: 共有333条查询结果,搜索用时 62 毫秒
51.
Evidence is mounting for a relationship between human semen quality and environmental/lifestyle/socioeconomic factors including long term health outcomes such as mortality. The relationship between pre-freeze and post-thaw semen quality in cancer patients and these factors are unknown. Frozen semen from 217 cancer patients was thawed and analysed using a validated CASA method. Post-thaw quality was matched and compared with WHO semen analysis performed prior to storage. The English Indices of Deprivation 2010 were matched with patients and then examined for relationships with pre-freeze and post-thaw semen quality. There is a relationship between semen quality and deprivation in cancer patients. Compared with pre-freeze semen quality, post-thaw semen quality has a stronger relationship with deprivation. Sperm cryopreservation may have potential as a systemic health diagnostic test and is predictive of cancer patient mortality.  相似文献   
52.
The objective of this retrospective clinical study was to compare pregnancy rates obtained after the use of endoscopic-assisted transcervical catheterization (EIU) or laparotomy (SIU) for insemination of frozen-thawed dog semen. Healthy bitches from various breeds were inseminated with semen from multiple donors processed by different freezing centers. Data from 118 inseminations (78 EIU and 40 SIU) performed between 2009 and 2011 were analyzed. Insemination timing was based on vaginal cytology, serum progesterone concentrations, and vaginoscopy. A ureterorenoscope and a CH-5 Transcervical insemination catheter were used for EIU; 28 of the bitches in this group were inseminated twice with the second insemination less than 12 hours after the first. The numbers of live morphologically normal sperm (LMNS) were determined to characterize insemination doses. Overall, pregnancy rate was greater (P < 0.05) in the EIU group (65%) than in the SIU group (45%). Pregnancy rates were greater (P ≤ 0.06) when more than 100 × 106 LMNS were inseminated regardless of insemination method; the greatest pregnancy rate was observed in the EIU group when this insemination dose was used (38/49; 78%). There was no significant difference in pregnancy rate whether one (69%) or two inseminations (64%) were performed in the EIU group. Complications in the SIU group included anesthetic-induced bradycardia during surgery, significant postsurgery pain, seroma formation over the abdominal incision, and delayed wound healing. No complications were noted during or after insemination in the EIU group. In conclusion, these results support the use of EIU as a noninvasive alternative to laparotomy for insemination of frozen-thawed dog semen. In addition, use of more than 100 × 106 LMNS is also recommended for insemination.  相似文献   
53.
目的:观察复合凝乳酶胶囊对不同亚型功能性消化不良儿童临床表现、营养状态和摄食行为的影响及安全性。方法:以2017年8月至2018年9月在湖北省妇幼保健院儿童消化内科就诊的功能性消化不良(Functional dyspepsia,FD)儿童为研究对象进行问卷调查,观察治疗前和复合凝乳酶治疗2 w后患儿临床症状变化及药物相关不良反应的发生情况,监测患儿身高和体重,进行膳食情况的调查。结果:共163例儿童纳入研究,发生餐后不适综合征(Postprandial distress syndrome, PDS)66例,上腹痛综合征(Epigastric pain syndrome, EPS)97例。治疗前,PDS组儿童症状总分明显高于EPS儿童(6.9±2.7 vs 3.6±1.7,t=5.90,P=0.00)。PDS组儿童WAZ、WHZ、HAZ、身高别体质量Z值(weight for height Z score,WHZ)、年龄别身高Z值(height for age Z score,HAZ)、年龄别体质量Z值(weight for age Z score,WAZ)、体质量指数(body mass index,BMI)、膳食多样化分数(Dietary diversity score, DDS)均明显低于EPS组(P均0.05)。治疗2 w后,PDS儿童症状总分明显降低(P=0.00),改善程度依次为:厌食早饱腹痛嗳气恶心腹胀。EPS儿童症状总分无明显变化(P=0.11)。PDS儿童WAZ、WHZ、DDS均有明显升高(P均0.05)。EPS儿童DDS无明显变化(t=0.22,P=0.30)。研究期间未见明显药物相关不良反应。结论:复合凝乳酶胶囊可改善PDS患儿的临床症状、营养状态和膳食多样性,且安全性高。  相似文献   
54.
摘要 目的:分析血清炎症因子联合T淋巴细胞亚群在急性呼吸窘迫综合征中的应用价值。方法:选择我院2021年7月至2022年12月收治的70例急性呼吸窘迫综合征患者作为研究对象,分为轻度组、中度组和重度组。检测所有入选者的血清炎症因子、T淋巴细胞亚群,分析急性呼吸窘迫综合征患者血清炎症因子、T淋巴细胞亚群与氧合指数(OI)、肺部超声B线数目的关系;观察急性呼吸窘迫综合征患者28 d后预后情况,分为死亡组与存活组,使用ROC曲线分析血清炎症因子联合T淋巴细胞亚群对急性呼吸窘迫综合征患者死亡的预测效能。结果:血清IL-6、IFN-γ表达水平、外周血Th17细胞比例、Th17/Treg比值在轻度组、中度组和重度组中差异显著,两两比较,差异显著(P<0.05);经Pearson相关性分析,急性呼吸窘迫综合征患者血清IL-6、IFN-γ表达水平、外周血Th17细胞比例、Th17/Treg比值均与OI呈负相关,与B线数目呈正相关(P<0.05);死亡组血清IL-6、IFN-γ表达水平、外周血Th17细胞比例均高于存活组,Th17/Treg比值大于存活组,差异显著(P<0.05);经ROC曲线分析,IL-6、IFN-γ联合Th17/Treg比值预测急性呼吸窘迫综合征患者死亡的AUC为0.935。结论:血清炎症因子、T淋巴细胞亚群与急性呼吸窘迫综合征病情严重程度有关,其中IL-6、IFN-γ联合Th17/Treg比值预测预后不良的效能较好,值得临床予以重视应用。  相似文献   
55.
目的:叶酸是一种水溶性B族维生素,在体内氨基酸与核苷酸代谢中起重要作用,是胎儿生长发育所必须的营养素。本文通过建立叶酸缺乏的孕鼠模型,探讨叶酸缺乏对胎鼠宫内发育的影响,并研究胎鼠肝脏组织中胰岛素生长因子(IGF)系统的表达变化。方法:雌性C57BL/6J小鼠叶酸缺乏组6只、正常对照组6只,分别饲以不舍叶酸和含2mg叶酸/kg的纯合饲料。四周后与雄鼠交配,于怀孕第13.5天(13.5dpc)对孕鼠剖腹取胎,观察和评价胎鼠发育指标,并对宫内发育迟缓(IUGR)比率进行统计。用Real-timePCR法检测胎鼠肝脏组织中胰岛素生长因子I(IGFI)、胰岛素生长因子I受体(IGFIR)、胰岛素生长因子II(IGFII)、胰岛素生长因子II受体(IGFIIR)、胰岛素生长因子结合蛋白1(IGFBP-1)和胰岛素生长因子结合蛋白3(IGFBP-3)mRNA的相对表达水平。结果:叶酸缺乏组雌鼠合笼前每日体重增长量降低,13.5dpc胎鼠吸收胎和死胎比率升高,胎重下降,IUGR比率显著升高,差异有统计学意义(P〈0.05);叶酸缺乏组胎鼠肝脏组织中IGFII和IGFIIRmRNA的相对表达水平均低于正常对照组(P〈0.05),IGFI、IGFIR、IGFBP-1和IGFBP-3mRNA的相对表达水平两组间没有差异(P〉0.05)。结论:叶酸缺乏会导致小鼠孕中期胎鼠IUGR比率升高及胎肝IGFII和IGFIIRmRNA的表达水平降低,提示叶酸缺乏对IGF系统基因的调控,可能与胎鼠I-UGR发生机制有关。  相似文献   
56.

Background

Epidemiological studies have revealed that intrauterine growth retardation (IUGR) or low birth weight is linked to the later development of asthma. Epigenetic regulatory mechanisms play an important role in the fetal origins of adult disease. However, little is known regarding the correlation between epigenetic regulation and the development of asthma following IUGR.

Methods

An IUGR and ovalbumin (OVA)-sensitization/challenge rat model was used to study whether epigenetic mechanisms play a role in the development of asthma following IUGR.

Results

Maternal nutrient restriction increased histone acetylation levels of the endothelin-1 (ET-1) gene promoter in lung tissue of offspring, but did not cause significant alterations of DNA methylation. The effect was maintained until 10 weeks after birth. Furthermore, these epigenetic changes may have induced IUGR individuals to be highly sensitive to OVA challenge later in life, resulting in more significant changes related to asthma.

Conclusions

These findings suggest that epigenetic mechanisms might be closely associated with the development of asthma following IUGR, providing further insight for improved prevention of asthma induced by environmental factors.  相似文献   
57.
董旻  ;赖洁  ;周威  ;卢凝  ;汤展宏 《蛇志》2014,(3):283-286
目的评价肺水相关指数对重症烧伤并发急性呼吸窘迫综合征(ARDS)患者严重程度、预后判断的价值。方法对31例重症烧伤并发ARDS患者,除记录一般临床资料及主要合并症外,均利用脉搏指示剂连续心输出量(PiCCO)监测仪监测,并记录置入PiCCO导管时的急性生理和慢性健康状况(APACHE)Ⅱ评分,置管后0、24、48、72h氧合指数,肺血管通透性指数(PVPI)和血管外肺水指数(EVLWI)值。根据28天预后分为存活组和死亡组,分析两组各指数之间的差异及其对预后的评估能力。结果纳入研究的31例患者中,28天内死亡21例(67.7%),吸入性损伤、脓毒血症是主要合并症及影响预后的主要因素。存活组患者置管后72h氧合指数高于死亡组,差异有统计学意义(P0.05);存活组患者置管后48、72hPVPI低于死亡组,差异有统计学意义(P0.05);存活组患者置管后24、48、72hEVLWI低于死亡组,差异有统计学意义(P0.05);且随着置管时间延长,氧合指数、PVPI、EVLWI均对预后评价准确性增加,置管后72h的氧合指数、PVPI、EVLWI值对预后的评价最佳,3个指数对预后评估价值差异无统计学意义(P0.05)。结论运用PiCCO监测仪对肺水相关指数连续监测对重症烧伤并发ARDS患者严重程度、预后评价具有重要临床意义。  相似文献   
58.
Hofbauer细胞起源于绒毛问质,是胎盘巨噬细胞,不仅能够吞噬入侵的病原微生物,参与母胎免疫反应;还可表达DC—SIGN、Fc等多种受体,这些受体分子可与乙肝病毒颗粒相互作用,使病毒通过跨膜转运进入细胞内。同时HofDauer细胞能够在母体间游走,当HBV感染Hofbauer细胞后,可借助HoPoauer细胞游走性介导HBV宫内感染。  相似文献   
59.
BackgroundPrehypertension is a precursor to hypertension status. Psychological distress has been identified earlier among hypertensives; however, there is little evidence for the presumptive relationship between prehypertension and psychological distress.ObjectiveThe study aimed to assess the psychological wellbeing of the Al-Kharj, Saudi Arabia population, using the General Health Questionnaire (GHQ-12) and correlating it with prehypertensive patients in the same population.MethodsA cross-sectional analysis of the population of Al-Kharj, Saudi Arabia, was carried out between January and June of 2016. With an 85 percent response rate, a total of 1016 participants participated in the study. A multiple linear regression analysis was performed to assess the relationship between prehypertension and psychological distress.ResultsThe findings of the adjusted analysis demonstrated that, on average prehypertensive patients were more distressed psychologically than non-hypertensive patients (unstandardized Beta regression coefficient = 3.600; P-value 0.025). Similarly, on average women were found to be more psychologically distressed than men (unstandardized Beta = 1.511, P-value 0.002). Civil workers and unemployed individuals were more psychologically distressed than employed individuals (unstandardized Beta = 1.326, P-value 0.041) while adjusting for the sociodemographic and other variables such as BMI, diabetes status, cholesterol, and smoking status.ConclusionThe current study shows that as compared to normotensive patients, self-rated mental wellbeing and psychological wellbeing are all considerably poorer among prehypertensive patients. To prevent individuals from having negative psychological outcomes and their long-term complications, the Government of Saudi Arabia needs to concentrate on prehypertensive, female, and unemployed individuals. Well-designed longitudinal studies, primarily in Saudi Arabia, are needed in the future to research the cause and impact of poor mental health and prehypertension.  相似文献   
60.
Numerous studies have shown that the opiate system is crucially involved in emotionally guided behavior. In the present study, we focussed on the medio‐rostral neostriatum/hyperstriatum ventrale (MNH) of the chick forebrain. This avian prefrontal cortex analogue is critically involved in auditory filial imprinting, a well‐characterized juvenile emotional learning event. The high density of μ‐opiate receptors expressed in the MNH led to the hypothesis that μ‐opiate receptor‐mediated processes may modulate the glutamatergic, dopaminergic, and/or serotonergic neurotransmission within the MNH and thereby have a critical impact on filial imprinting. Using microdialysis and pharmaco‐behavioral approaches in young chicks, we demonstrated that: the systemic application of the μ‐opiate receptor antagonist naloxone (5, 50 mg/kg) significantly increased extracellular levels of 5‐HIAA and HVA; the systemic application of the specific μ‐opiate receptor agonist DAGO (5 mg/kg) increased the levels of HVA and taurine, an effect that was antagonized by simultaneously applied naloxone (5 mg/kg); the local application of DAGO (1 mM) had no effects on 5‐HIAA, HVA, glutamate, and taurine, however, the effects of systemically injected naloxone (5 mg/kg) were abolished by simultaneously applied DAGO (1 mM); the systemic application of naloxone (5 mg/kg) increased distress behavior (measured as the duration of distress vocalization during separation from the peer group). These results are in line with our hypothesis that the μ‐opiate receptor‐mediated modulation of serotonergic and dopaminergic neurotransmission alters the emotional and motivational status of the animal and thereby may play a modulatory role during filial imprinting in the newborn animal. © 2004 Wiley Periodicals, Inc. J Neurobiol, 2005  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