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991.
The penetrability of cervical mucus improves over the follicular phase. When the length of the follicular phase varies due to variation in the timing of the luteinizing hormone surge, mucus penetrability will also improve as the phase lengthens. As selection for Y spermatozoa decreases with improvements in mucus penetrability, sex ratios at conception should decline in longer follicular phases. Sex ratios should also decline as the time of insemination approaches ovulation unless hormonally-induced improvements in penetrability are reduced by the debris left by earlier inseminations.   相似文献   
992.
One way to improve our understanding of cortical anatomy is to visualize the three-dimensional (3D) shape of the cerebral sulci which is normally hidden. Here, we reconstructed the 3D morphology of the central sulcus (CS) in 17 normal subjects, using conventional magnetic resonance images and dedicated software. We found that the 3D morphology was remarkably consistent in all central sulci. Our analyses revealed three different regions (upper, middle and lower), which were easily identifiable by morphological criteria and sharply interconnected in the reconstructed CS. These morphological regions appear to have a strong functional significance, since the middle region corresponded precisely to the 'hand area', as verified by hand vibration positron emission tomography activation studies in eight cases. These data suggest that the 3D anatomy of the cerebral cortex may facilitate sulcal recognition, and sulcal subdivision into smaller morphological elements, bearing remarkable relationships with functional cortical maps.   相似文献   
993.
Burke  MW; Windham  JP; Thrall  JH; Shetty  PC; Brymer  JF 《Radiology》1987,164(1):267-269
The authors developed a postprocessing technique, eigenimage filtering, to extract phase-dependent information from digital subtraction angiograms of the heart. This technique suppresses the interference from the right ventricle and left atrium and produces an image of the left ventricle and aorta that is substantially free of these overlap artifacts. The resultant eigenimages of the heart appear more like conventional ventriculograms than do digital subtraction angiograms and matched filtered images.  相似文献   
994.
Left ventricular free wall rupture is thought to account for approximately 15% of deaths following acute myocardial infarction (MI). We present a case of left ventricular free wall rupture in a 64-year-old man following a lateral MI. The diagnosis was made with 2D and colour flow Doppler echocardiography. Unfortunately the patient died before emergency surgery, could be performed.  相似文献   
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Headache parameters, personality variables and stress factors were assessed in a sample of about 2,300 school pupils between 10 and 17 years of age in Amsterdam. More than 15% of the subjects reported headaches occurring weekly. Fear of failure and school problems, but not achievement motivation, had significant positive correlations with headache complaints after correction for differences in sex and age. Menarche and social class had little bearing in relation to the headache variables. From all reported causes of headache, stress was mentioned most frequently in both elementary and secondary schools.  相似文献   
999.
BACKGROUND: Non-response analysis is often restricted to the influence of age, sex and socio-economic status on response status. In this study the health status of responders and non-responders was also compared. RESULTS: Responders were comparable to non-responders with regard to the number of diagnosed disorders as well as to the prevalences of disorders within body systems. Non-responders only showed psychological disorders more often. CONCLUSION: It is useful to assess the relation between non-response and morbidity patterns in other studies as well, in order to detect selective non-response and bias.   相似文献   
1000.
The objective of this study was to determine if assisted hatching improved the rates of implantation, clinical pregnancy and ongoing pregnancy for in-vitro fertilization (IVF) patients aged > or =36 years. On the day of oocyte aspiration, consenting patients were randomized according to whether all embryos underwent the hatching procedure (hatched; n = 41) or all embryos remained unhatched (controls; n = 48). Patients in both groups were treated with methylprednisolone and doxycycline starting on the day of oocyte retrieval and continuing for 4 days. The hatching procedure was performed approximately 55 h after insemination on all potential embryos for transfer and employed the release of acidified acid Tyrode's medium against the zona pellucida to create an opening approximately 20 microm in diameter. No significant differences were noted in the mean age, number of oocytes aspirated and number of embryos transferred between the hatched and control groups. In addition, no significant differences were observed in the rates of implantation (11.1 versus 11.3%), clinical pregnancy (39.0 versus 41.7%) and ongoing pregnancy (29.3 versus 35.4%) between the hatched and control groups respectively. These results suggest that assisted hatching may have no significant impact on IVF success rates in the patient population studied.   相似文献   
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