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   168篇
  免费   6篇
  2022年   3篇
  2021年   2篇
  2020年   7篇
  2019年   7篇
  2018年   4篇
  2017年   4篇
  2016年   4篇
  2015年   9篇
  2014年   13篇
  2013年   9篇
  2012年   10篇
  2011年   12篇
  2010年   5篇
  2009年   3篇
  2008年   7篇
  2007年   2篇
  2006年   6篇
  2005年   1篇
  2004年   10篇
  2003年   3篇
  2002年   6篇
  2001年   3篇
  2000年   6篇
  1999年   4篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   5篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1988年   1篇
  1986年   6篇
  1984年   1篇
  1983年   2篇
  1980年   1篇
  1975年   1篇
排序方式: 共有174条查询结果,搜索用时 31 毫秒
1.
ABO, Rh and MN blood groups were studied among the people of Ahwaz, Khuzistan, Iran. The people of Ahwaz are characterized by high frequencies of the blood groups 0 (41.16%), Rh-positive (90.0%) and MN (48.13%). These frequencies are significantly different from those obtained in other Iranian populations, which is caused by the co-operation of various factors.  相似文献   
2.
234 218 births (1975-1983) from a hospital in Tehran have been analysed for seasonality of birth and sex ratio. The results show more births in winter and less births in fall. The sex ratio is higher in summer and lower in fall. The occurrence of multibirths shows higher twinning and triplet rates in spring and fall, respectively, whereas lower twinning and triplet rates occur in winter and summer, respectively. It could be demonstrated that geographical factors influence the rates of births and multibirths as well as the sex ratio.  相似文献   
3.
Preimplantation embryo development was arrested at the premorula stage in hamsters ovariectomized on Day 1 of pregnancy. This effect was reversed when 500 micrograms progesterone were administered daily. Oestradiol-17 beta given alone had no significant effect on the cleavage rate or blastocyst formation, but a synergistic response was evident when a suboptimal (30 micrograms) dose of progesterone was given with 50 ng oestradiol-17 beta. Cholesterol and hydrocortisol had no effect on embryo development.  相似文献   
4.
We analyzed bilateral finger prints of 3158 individuals from 13 Iranian populations of diverse origins, for digital patterns, using the topological method. Some male/female differences, and a great deal of heterogeneity in interpopulational variation was observed. Distance analysis, and the resultant dendrograms separated the populations studied, but the separation was not in agreement with the known ethnohistory of this region. Comparison of the obtained results with those based on the traditional methodology showed that the traditional methodology gives better results in measuring population distances.  相似文献   
5.
Embryos recovered from sows on Days 9-13 of pregnancy (Day 0 = first day of estrus) exhibited saturable and time-dependent specific binding of 125I-epidermal growth factor (EGF). The specific binding (pg/mg protein) was greater (P less than 0.001) for Day 13 elongated conceptuses than for conceptuses of earlier stages. Scatchard analyses showed two classes of binding sites (Kd = 7.0 +/- 2.6 x 10(-11) M, Bmax = 6.2 +/- 1.4 fmol/mg protein and Kd = 3.4 +/- 0.2 x 10(-8) M, Bmax = 420 +/- 80 fmol/mg protein). The EGF receptor in Day 13 conceptus membranes is a 170-kDa protein and was phosphorylated in the presence of EGF and adenosine triphosphate. EGF stimulated protein tyrosine kinase activity about 1.6-fold over basal levels. The results show that the preimplantation pig conceptus possesses EGF-binding sites with the properties of functional EGF-receptors.  相似文献   
6.
The bilateral palmar prints of 3,158 females and males from 13 Iranian populations of diverse origins were analyzed to see how well topological palmar pattern frequencies reflect population distances. The results showed bimanual variation among most of the populations studied. Sex variation showed significant differences among all of the populations studied. Distance analysis and constructed dendrograms showed separation between the populations studied. These distances were frequently in agreement with the known ethnohistoric background of the populations studied. The male data gave better results. It appears that topological palmar patterns are a better indicator of population distance than topological finger patterns.  相似文献   
7.
This study addresses mechanisms for the generation and selection of visual behaviors in anamniotes. To demonstrate the function of these mechanisms, we have constructed an experimental platform where a simulated animal swims around in a virtual environment containing visually detectable objects. The simulated animal moves as a result of simulated mechanical forces between the water and its body. The undulations of the body are generated by contraction of simulated muscles attached to realistic body components. Muscles are driven by simulated motoneurons within networks of central pattern generators. Reticulospinal neurons, which drive the spinal pattern generators, are in turn driven directly and indirectly by visuomotor centers in the brainstem. The neural networks representing visuomotor centers receive sensory input from a simplified retina. The model also includes major components of the basal ganglia, as these are hypothesized to be key components in behavior selection. We have hypothesized that sensorimotor transformation in tectum and pretectum transforms the place-coded retinal information into rate-coded turning commands in the reticulospinal neurons via a recruitment network mimicking the layered structure of tectal areas. Via engagement of the basal ganglia, the system proves to be capable of selecting among several possible responses, even if exposed to conflicting stimuli. The anatomically based structure of the control system makes it possible to disconnect different neural components, yielding concrete predictions of how animals with corresponding lesions would behave. The model confirms that the neural networks identified in the lamprey are capable of responding appropriately to simple, multiple, and conflicting stimuli.  相似文献   
8.
9.
10.
Probiotics and Antimicrobial Proteins - This study was conducted to evaluate different doses of two species of Bacillus (Bacillus licheniformis and Bacillus subtilis), on growth parameters,...  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