منابع مشابه
Decreasing sperm quality: a global problem?
BACKGROUND Carlsen and coworkers (1992) reviewed 61 heterogeneous observational studies on semen quality published between 1938 and 1990. This review indicates that mean sperm density decreased significantly between 1940 and 1990. An extended meta-analysis with 101 studies confirmed a decline in sperm density for the period from 1934 to 1996 (2000). The key message of the meta-analyses is that ...
متن کاملapplication of upfc based on svpwm for power quality improvement
در سالهای اخیر،اختلالات کیفیت توان مهمترین موضوع می باشد که محققان زیادی را برای پیدا کردن راه حلی برای حل آن علاقه مند ساخته است.امروزه کیفیت توان در سیستم قدرت برای مراکز صنعتی،تجاری وکاربردهای بیمارستانی مسئله مهمی می باشد.مشکل ولتاژمثل شرایط افت ولتاژواضافه جریان ناشی از اتصال کوتاه مدار یا وقوع خطا در سیستم بیشتر مورد توجه می باشد. برای مطالعه افت ولتاژ واضافه جریان،محققان زیادی کار کرده ...
15 صفحه اولEvidence for decreasing quality of semen during past 50 years.
OBJECTIVE To investigate whether semen quality has changed during the past 50 years. DESIGN Review of publications on semen quality in men without a history of infertility selected by means of Cumulated Index Medicus and Current List (1930-1965) and MEDLINE Silver Platter database (1966-August 1991). SUBJECTS 14,947 men included in a total of 61 papers published between 1938 and 1991. MAI...
متن کاملEvidence for decreasing sperm count in African population from 1965 to 2015.
PURPOSE This meta-analysis, following our previous reports those documented an overall 57% diminution in mean sperm concentration around the globe over past 35 years and 32.5% decline in past 50 years in European population, attempts to report the declining trend of sperm concentrations in African population between 1965 and 2015. METHODS In the course of retrieval of data following MOOSE gui...
متن کاملDecreasing quality of semen
produce a measure of relative differences in each country. The figure combines the data for neonatal and postneonatal mortality and shows that England and Wales have a steeper and more consistent gradient of mortality across social classes than Sweden. The width of the "steps" is proportional to each class's share of total live births. The differences in total mortality and its socioeconomic di...
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ژورنال
عنوان ژورنال: BMJ
سال: 1995
ISSN: 0959-8138,1468-5833
DOI: 10.1136/bmj.311.7004.569c