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   196篇
  免费   22篇
  2024年   1篇
  2023年   1篇
  2022年   1篇
  2021年   3篇
  2020年   8篇
  2019年   5篇
  2018年   4篇
  2017年   8篇
  2016年   9篇
  2015年   7篇
  2014年   10篇
  2013年   13篇
  2012年   9篇
  2011年   10篇
  2010年   10篇
  2009年   10篇
  2008年   13篇
  2007年   8篇
  2006年   4篇
  2005年   6篇
  2004年   11篇
  2003年   8篇
  2002年   5篇
  2001年   2篇
  2000年   3篇
  1999年   6篇
  1997年   1篇
  1993年   1篇
  1992年   5篇
  1991年   7篇
  1990年   1篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1986年   1篇
  1985年   3篇
  1984年   2篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1978年   2篇
  1977年   5篇
  1976年   4篇
排序方式: 共有218条查询结果,搜索用时 109 毫秒
211.
The degradation of ornithine decarboxylase was studied by an immunoblotting technique. The immunoblots of mouse kidney and brain cytosol preparations revealed degradation fragments of unequal size. The immunoreactive fragments found in kidney cytosol corresponded to molecular weights of 46 kDa and 32 kDa, whereas 36 kDa fragment was dominant in brain cytosol. When kidney cytosol was exposed to microsomal fraction of mouse brain before analysis, the kidney enzyme was degraded to 36 kDa-fragment. The microsomal fraction of mouse kidney, in turn, when incubated with brain cytosol brought about the appearance of immunoreactive protein corresponding to molecular weight of 35 kDa that was also found in kidney preparation, which was incubated as homogenate before electrophoretic run and immunoblotting. These results show that microsomal fractions effectively degrade enzyme protein, and suggest that the regulation mechanisms by the in vivo degradation of the enzyme are dissimilar in these tissues.  相似文献   
212.
46 postmenopausal women with estrogen receptor positive breast cancer entered a phase II study with a novel antiestrogen, toremifene. Patients had either recurrent or primarily inoperable advanced disease. No prior or concurrent cytostatic or hormonal treatment was allowed. Eight patients (17%) achieved complete response (CR), 17 (37%) partial response (PR) and 13 (28%) had stabilization of their disease at least for three months. The mean durations of responses were 52 +, 53 + and 27 + weeks, respectively, with 5 patients in CR, 6 in PR and 1 with no change (NC) still continuing the treatment. No significant differences could be seen in response rates according to the concentration of estrogen receptors or presence of progesteron receptors in this group of patients. Toxicity was not a problem, in general, the treatment was well tolerated. Two side effects (sweating and vertigo) were classified as severe and one patient after achieving PR interrupted the treatment because of tremor.  相似文献   
213.
The association between abdominal obesity and atherogenic lipid profile emerges from complex interactions of genes and environment. We aimed to explore the heritability and effects of overweight on serum lipid profile (high‐density lipoprotein‐cholesterol (HDL‐C), HDL mean particle size, percentages of HDL2b, 2a, 3a, 3b, and 3c, low‐density lipoprotein‐cholesterol (LDL‐C), LDL peak particle size and triglycerides (TGs)) in healthy, young adults. HDL‐C, LDL‐C, and TG were measured in 52 monozygotic (MZ) and 89 dizygotic (DZ) twin pairs, aged 23–32 years, chosen to represent a wide range of BMIs (17.6–42.9 kg/m2). Of them, 24 MZ and 26 DZ pairs were chosen at random for measurements of HDL mean and LDL peak particle sizes and percentages of HDL subspecies. The heritabilities of the lipid parameters adjusted for BMI were HDL‐C 73%, HDL mean particle size 56%, HDL subspecies 46–63%, LDL‐C 79%, LDL peak particle size 49%, and TG 64%. Genetic and environmental correlations between BMI and HDL‐C, LDL‐C, and TG were modest (0.3–0.4). Abdominal overweight (waist circumference ≥94 cm for males and ≥80 cm for females) associated with decreased HDL‐C, increased LDL‐C, and TG concentrations, smaller HDL mean particle size, lower HDL2b, and higher HDL3c percentages in both genders. Within MZ twins, controlling for genetic influences, within‐pair differences in HDL3c percentage were associated with those in waist (r = 0.46, P = 0.032) and BMI (r = 0.51, P = 0.013). In conclusion, serum lipid parameters, including LDL peak and HDL mean particle sizes and HDL subspecies distribution are under strong genetic control. Overweight associated with significant lipid profile changes, particularly, small HDL3c increased in overweight independent of genetic influences.  相似文献   
214.
215.
216.
217.
Previous investigations have ascertained, according to the results obtained by Bradley et al. (1980) in the sheep, that the laryngeal surface of the epiglottis of goat and bovine is always provided with numerous taste buds. These observations have verified in other ruminant species, as the moufflon and the buffalo, the validity of the above-named datum and have ascertained that it is always inconstant in the other animal species considered (wild boar, coypu). These taste buds show a typical structure (diameter of the outer taste pore varying from 2.7 to 4.2 micron, width of the chemoreceptors varying from 30 to 60 micron and length from 27.5 to 57.5 micron). Moreover, the normal structure of the above-named taste buds is also testified by the arrangement of their innervation and particularly by the integrity of the synaptic contacts. The results of the present research have permitted a critical and more severe examination of the probable functional role of those laryngeal receptors. In fact, in the ruminants they may protect the deep airways precluding to food particles the larynx in the phase of food regurgitation.  相似文献   
218.
The relative roles of genetics and developmental plasticity in creating phenotypes adapted to prevailing conditions are insufficiently understood. In potentially multivoltine temperate insects, individuals that do not enter diapause but develop directly into reproductive adults within the same season are severely time-constrained. Direct development is, however, under selection only if expressed in the wild. Thus, adaptive correlates of the direct development are expected to evolve and persist only in multivoltine populations. We studied the genetic and phenotypic components of variation in juvenile development in the geometrid moth Chiasmia clathrata from univoltine and bivoltine regions. Larvae were reared at two temperatures (14/20 °C) and densities (low/high) in a factorial split-brood experiment. High temperature and low density promoted direct development, the former condition being associated with a short development time, high growth rate and large body size. Genotypes of bivoltine origin had a higher propensity for direct development and seemingly expressed an exaggerated plastic response to increasing temperature compared to the ones from univoltine populations. Alternative life history phenotypes associated with the induced developmental pathway emerged only in the bivoltine region, direct development resulting in a short larval period, high growth rate and small size at 20 °C there. The degree of differentiation between the developmental pathways was insensitive to larval density; high density only decreased both development time and body size to a certain degree. We conclude that the differences between the pathways are not due to the induction of a particular pathway itself, but geographically varying selection pressures shape the correlation structure among life history traits and their pathway-specific expression.  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