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   130篇
  免费   24篇
  国内免费   2篇
  2024年   1篇
  2023年   5篇
  2022年   11篇
  2021年   5篇
  2020年   15篇
  2019年   5篇
  2018年   6篇
  2017年   5篇
  2016年   6篇
  2015年   6篇
  2014年   16篇
  2013年   9篇
  2012年   6篇
  2011年   11篇
  2010年   6篇
  2009年   3篇
  2008年   4篇
  2007年   2篇
  2006年   4篇
  2005年   3篇
  2004年   5篇
  2002年   3篇
  2001年   1篇
  1999年   2篇
  1998年   2篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1984年   1篇
  1980年   1篇
排序方式: 共有156条查询结果,搜索用时 15 毫秒
121.

Background

Few risk factors have been established for childhood germ cell tumors (GCT). Parental infertility and infertility treatment may be associated with GCT development but these risk factors have not been fully investigated.

Methods

A case–control study of childhood GCT was conducted through the Children's Oncology Group (COG). Cases, under the age of 15 years at diagnosis, were recruited through COG institutions from January 1993 to December 2002. Controls were obtained through random digit dialing. Information about infertility and infertility treatment along with demographic factors was collection through maternal interviews. Subgroups created by gender, age at diagnosis, and tumor location were examined separately. Statistical analysis was performed using multivariate logistic regression models.

Results

Overall, no association between GCT and infertility or its treatment was found. In subgroup analysis, females whose mothers had two or more fetal losses were found to be at increased risk for non-gonadal tumors (Odds ratio (OR) = 3.32, 95% Confidence interval (CI) = 1.12–9.88). Younger maternal age was associated with a lower risk of gonadal GCT in females (OR = 0.52, 95% CI = 0.28–0.96). There was an increased risk of all GCT and gonadal GCT in males born to older mothers (OR = 2.88, 95% CI = 1.13–7.37 and OR = 3.70, 95% CI = 1.12–12.24).

Conclusion

While no association between parental infertility or its treatment and childhood GCT was found overall, possible associations with maternal age and history of recurrent fetal loss were found in subgroups defined by gender.  相似文献   
122.
The occurrence of Chlamydophila abortus in female camels affected with ovarian hydrobursitis and a trial for medical treatment were studied. A total of 111 cases were included in two experiments. In Experiment 1, sera from 51 affected cases were tested for C. abortus antibody using enzyme-linked immunosorbent assay (ELISA). In Experiment 2, 60 female camels affected with bilateral ovarian hydrobursitis were divided into treated and control groups (n = 30 each). Based on the bursal diameter, females of both groups were subdivided into those having small (< 5 cm), medium (5-7 cm) or large (> 7 cm) bursae. Treated group received 20 mg/kg body weight oxytetracycline intramuscular, 4% lotagen intrauterine, and 500 μg cloprostenol intramuscular. Controls did not receive any treatment. All females were observed for 90 days non-return rate (NRR) and calving rate (CR). Antibodies against C. abortus were observed in 44/51 (86.3%) of the affected females. The 90 days NRR of the treated and control groups were 13/30 (43.3%) and 0/30 (0.0%), respectively, (P = 0.001), while the CR were 10/30 (33.3%) and 0/30 (0.0%), respectively, (P = 0.01). Based on bursal size, the 90 days NRR were 11/15 (73.3%), 2/7 (28.6%) and 0/8 (0.0%) for treated females having small, medium and large bursa, while the CR were 9/15 (60%), 1/7 (14.3%), and 0/8 (0.0%), respectively, (P = 0.01). In conclusion, it seems that C. abortus may be responsible for the spreading of the ovarian hydrobursitis syndrome in dromedaries. Small sized bursa could be medically treated.  相似文献   
123.
The aim of this study was to screen infertile men for HFE H63D mutation in correlation with clinical characteristics of infertile men (sperm concentration, sperm motility, morphology, testicular volume, Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH) and total Testosterone levels) and find out if the HFE H63D mutation has an effect on male infertility. After excluding hormonal treatment, any scrotal pathology, having any systemic diseases such as diabetes mellitus, sickle cell anemia and microdeletions of the Y chromosome, a total of 148 infertile men with age range between 17 and 52-years-old (average age 29.6 ± 7.2) were enrolled into the study. Our analysis indicates that the mean FSH levels are significantly higher (6.3 ± 4.6 mIU/ml, P = 0.03), whereas sperm motility is significantly lower (36.6 ± 28.1%, P = 0.01) in the infertile men with the HFE H63D mutation compared with subjects lacking this mutation. Comparison of allele frequencies of the infertile men with Ts < 50% versus the infertile men with Ts > 50% revealed a significant difference as expected (P = 0.001, OR = 0.14, %95 CI = 0.04–0.44). Comparison of allele frequencies of infertile men with abnormal sperm motility versus infertile men with normal sperm motility revealed a highly significant difference (P = 0.005, OR = 3.11, %95 CI = 1.41–6.86). Thus, the HFE H63D mutation seems to be an important risk factor for impaired sperm motility and is clinically associated with male infertility.  相似文献   
124.
125.
126.
A simple method for rapid evaluation of bull and ram sperm concentration is described. In this technique, a sample from an undiluted specimen was placed in a special 10-mum counting chamber and examined either by an ordinary or a phase-contrast microscope. The pattern distribution of the observed spermatozoa was matched as closely as possible with one of five pictures of a standard scale. This scale was prepared from serial photomicrographs that ranged from 100 to 1500 million per ml. The number that appeared at the corresponding photograph immediately indicated the sperm concentration of the tested specimen. In this way values up to 1500 million per ml could be determined rapidly with no further procedures. More concentrated specimens needed slight dilution to make them suitable for direct evaluation. Accuracy and reliability were statistically evaluated; the mean deviation from the conventional method was less than 15.2% with confidence level of 95%.  相似文献   
127.
本文采用酶细胞化学方法,在光镜下用积分分级计数法,全自动图像分析仪检测精子LDH-C4活性,两法测定LDH-C4活性显著正相关(r=0.801和0.742,P<0.01);LDH-C4酶细胞化学电镜技术观察精子LDH-C4活性,通过计数酶点可测定LDH-C4活性。本文检查38例不育男性和20例已生育男性精子LDH-C4活性,LDH-C4主要分布于精子STM及胞质,其次是顶体及质膜表面。可通过胞膜外逸到精浆,LDH-C4在各部活性比值为5∶2∶1∶1。不育组精子LDH-C4可能通过膜破损处外漏到精浆使精子内LDH-C4显著减少,LDH-C4在精子顶体亦显著减少,使不育组精子LDH-C4活性显著低于生育组精子,提示LDH-C4活性的定位和大小直接与生育能力相关,检测LDH-C4活性可作为检查不育症精子质量的可靠指标。LDH-C4与精子密度显著相关(r=0.737和-0.493,P<0.05);与活动性无相关性。  相似文献   
128.
The regulation and possible function of the preproenkephalin gene in testis were studied in vivo in transgenic mice containing: (1) bases ?193 to +210 of the human proenkephalin gene and an additional one kilobase of 3' proenkephalin flanking sequence driving expression of bacterial chloramphenicol acetyltransferase (CAT), and (2) the same promoter and flanking sequences driving expression of a rat proenkephalin cDNA. Five lines of mice, designated HEC1–5, expressed the first construct and 10, HER1–10, the second. Each HEC male and many HER males showed dramatic expression of the transgene in the testis, although much lower expression was observed in the brain and other enkephalin-producing tissues. High levels of expression in testis can thus be achieved with a very short promoter region and do not require intron A sequences previously considered necessary. Altered enkephalin expression may affect testicular function. One founder, HER8, displayed grossly abnormal testicular morphology and was completely infertile. A second founder, HER6, had low sperm motility. Two offspring from other lines also displayed subnormal fertility. These studies support a role for specific promoter sequences in testis expression and may further support a significant role for proenkephalin in testicular function. © 1994 Wiley-Liss, Inc.  相似文献   
129.
130.
解脲脲原体感染与不孕不育   总被引:1,自引:0,他引:1  
解脲脲原体是人类泌尿生殖道常见的寄生菌之一,它可以引起男女泌尿生殖道感染,其中最严重的后果认为可导致男女不孕不育。支原体感染是否与男性和女性的不孕不育有关,其致病的主要机制是什么,探讨这些问题对于防治解脲脲原体感染,减少及避免不孕不育疾病的发生有重要意义。本文对近年来关于解脲脲原体感染导致女性不孕和男性不育的机制进行了综合概述。  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