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   62篇
  免费   4篇
  66篇
  2023年   1篇
  2021年   1篇
  2018年   1篇
  2017年   1篇
  2015年   3篇
  2013年   2篇
  2012年   6篇
  2011年   3篇
  2010年   7篇
  2009年   6篇
  2008年   3篇
  2007年   4篇
  2006年   4篇
  2005年   3篇
  2004年   2篇
  2003年   2篇
  2001年   1篇
  1999年   1篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
  1992年   3篇
  1991年   1篇
  1989年   1篇
  1986年   1篇
  1981年   1篇
  1980年   1篇
  1977年   1篇
  1955年   1篇
排序方式: 共有66条查询结果,搜索用时 0 毫秒
11.
Disorders of sexual development are rare in non‐human primates. We report a case of true hermaphroditism in a 19‐year‐old, nulliparous, female baboon (Papio spp.). At necropsy, the animal was obese with adequate muscle mass and hydration. Reproductive organs appeared normal with the exception of 2 firm nodular structures in the myometrium (1‐1.5 cm diameter) and a thickened, dark endocervical mucosa. Histologically, both gonads were ovotestes and contained discrete areas of ovarian and testicular tissue. There were follicles in various stages of development surrounded by ovarian stroma. Other areas contained hypoplastic seminiferous tubules lined by Sertoli cells, but lacked germ cells and spermatozoa. The uterine lesions were consistent with adenomyosis and cystic endometrial hyperplasia. Cervical lesions were consistent with atypical glandular hyperplasia and squamous metaplasia with dysplasia. We report the first case of ovotesticular disorder of sexual development (OT‐DSD), or true hermaphroditism in a baboon.  相似文献   
12.
The physiological condition of nestling altricial birds depends on the quantity and quality of food delivered to them by parents. One indicator of the condition of Great Tit Parus major nestlings is the haemoglobin concentration in their blood. The present study demonstrates the influence of weather conditions (temperature and rainfall) on nestling haemoglobin concentrations during two consecutive breeding seasons in two different habitat types (parkland vs. woodland) in the city of Łódź in Central Poland. This influence probably results from the effects of weather on the trophic base of the Tits. Dry, hot weather strongly affected bush and herbal foliage later in the breeding season (mid-June to mid-July) in 2006, presumably by interfering with the development of herbivorous arthropod populations. This in turn caused food shortages for second broods of Great Tits, which resulted in nestlings having low haemoglobin levels. In the following year, temperature was on average lower, and rainfall was regular but not very heavy. These conditions enabled the development of arthropod assemblages, and the trophic base for birds was much richer. Haemoglobin concentrations in the blood of nestlings from second broods were significantly higher than those of first broods and, unexpectedly, second-brood nestlings in 2007 were on average in better physiological state than first-brood nestlings in 2006 in both habitats. The relationship between haemoglobin concentration, brood category and year was very similar to that for nestling body mass. However, it was independent of both body mass and brood size. In some years and under certain conditions, second broods can be more successful than first broods.  相似文献   
13.
In this study, we describe a rapid microtiter serum bactericidal assay (RMSBA) that can be used to measure the functionality of immune sera. It quantifies bactericidal activity of immune sera in the presence of complement against a homologous bacterium, M. haemolytica in this case. There is high correlation between data from RMSBA and standard complement-mediated bacterial killing assay (r=0.756; p<0.0001). The RMSBA activity of sera can be generated in less than 5 h instead of overnight incubation. RMSBA costs substantially less in terms of time, labor, and resources and is highly reproducible.  相似文献   
14.
Involvement of FtsZ in coupling of nucleoid separation with septation   总被引:9,自引:0,他引:9  
The cell-cycle parameters of an Escherichia coli strain expressing essential division gene ftsZ at one-fifth of its normal level, because of antisense regulation by DicF RNA, have been analysed. Inhibition of FtsZ expression affects neither the generation time nor the replication initiation mass, the C period, or the constriction period, but it does dramatically retard the initiation of constriction relative to replication termination. Separation of the nucleoids is equally postponed, indicating that division is not coupled to termination of replication, but to partitioning. The severe inhibition of nucleoid separation by DicF RNA, and its suppression by overproduction of FtsZ, suggest a role for FtsZ in the control of separation, and consequently in the coupling of separation and division. We suggest that the normal pattern of nucleoid separation previously found in cells deficient in ftsZ function was a consequence of the loss of a negative effect exerted by FtsZ on separation. In agreement with this view, we find that nucleoid separation is temporarily inhibited after arrest of FtsZ synthesis, but is later resumed as FtsZ is further diluted into the elongating filaments.  相似文献   
15.
We describe a novel immobilization technique to investigate interactions between immobilized gangliosides (GD3, GM1, and GM2) and their respective antibodies, antibody fragments, or binding partners using an optical biosensor. Immobilization was performed by direct injection onto a carboxymethyldextran sensor chip and did not require derivatization of the sensor surface or the ganglioside. The ganglioside appeared to bind to the sensor surface by hydrophobic interaction, leaving the carbohydrate epitope available for antibody or, in the case of GM1, cholera toxin binding. The carboxyl group of the dextran chains on the sensor surface did not appear to be involved in the immobilization as evidenced by equivalent levels of immobilization following conversion of the carboxyl groups into acyl amino esters, but rather the dextran layer provided a hydrophilic coverage of the sensor chip which was essential to prevent nonspecific binding. This technique gave better reactivity and specificity for anti- ganglioside monoclonal antibodies (anti-GD3: KM871, KM641, R24; and anti-GM2: KM966) than immobilization by hydrophobic interaction onto a gold sensor surface or photoactivated cross-linking onto carboxymethydextran. This rapid immobilization procedure has facilitated detailed kinetic analysis of ganglioside/antibody interactions, with the surface remaining viable for a large number of cycles (>125). Kinetic constants were determined from the biosensor data using linear regression, nonlinear least squares and equilibrium analysis. The values of kd, ka, and KAobtained by nonlinear analysis (KAKM871 = 1.05, KM641 = 1.66, R24 = 0.14, and KM966 = 0.65 x 10(7) M- 1) were essentially independent of concentration and showed good agreement with data obtained by other analytical methods.   相似文献   
16.
17.
Exercising or working in a hot, humid environment can results in the onset of heat-related illness when an individual''s temperature is not carefully monitored. The purpose of the present study was to compare three techniques (data loggers, thermal imaging, and wired electrodes) for the measurement of peripheral (bicep) and central (abdominal) skin temperature. Young men and women (N = 30) were recruited to complete the present study. The three skin temperature measurements were made at 0 and every 10-min during 40-min (60% VO2max) of cycling in a hot (39±2°C), humid (45±5% RH) environment. Data was statistically analyzed using the Bland-Altman method and correlation analysis. For abdominal skin temperature, the Bland-Altman limits of agreement indicated that data loggers (1.5) were a better index of wired than was thermal imaging (3.5), For the bicep skin temperature the limits of agreement was similar between data loggers (1.9) and thermal (1.9), suggesting the both were suitable measurements. We also found that when skin temperature exceeded 35°C, we observed progressively better prediction between data loggers, thermal imaging, and wired skin sensors. This report describes the potential for the use of data loggers and thermal imaging to be used as alternative measures of skin temperature in exercising, human subjects.  相似文献   
18.
A new α-galactosyl binding lectin was isolated from the fruiting bodies of the mushroom Lyopyllum decastes. It is a homodimer composed of noncovalently-associated monomers of molecular mass 10,276 Da. The lectin’s amino acid sequence was determined by cloning from a cDNA library using partial sequences determined by automated Edman sequencing and by mass spectrometry of enzyme-derived peptides. The sequence shows no significant homology to any known protein sequence. Analysis of carbohydrate binding specificity by a variety of approaches including precipitation with glycoconjugates and microcalorimetric titration reveals specificity towards galabiose (Gal α1,4Gal), a relatively rare disaccharide in humans. The lectin shares carbohydrate binding preference with the Shiga-like toxin, also known as verocytoxin, present in the bacteria Shigella dysenteriae and Escherichia. coli 0157:H7, both of which are causes of outbreaks of sometimes fatal food-borne illnesses.  相似文献   
19.
Toews et al. assert that strong reproductive isolation in Vermivora is inconsistent with other lines of evidence. Here, we discuss how strong yet incomplete reproductive isolation is consistent with other results from this system.  相似文献   
20.
The activity of acid lipase and the level of gibberellin A4 (GA4) were determined in apple embryos excised from seeds after different time periods of stratification and subsequently cultured in darkness at 4°C or at 25°C. Enzyme activity and GA4 content were higher at 4°C. Exogenous gibberellin stimulated lipase activity, while AMO-1618, an inhibitor of gibberellin biosynthesis, inhibited, to the same degree, both the enzyme activity and the GA4 accumulation. The involvement of GA4 and lipolytic enzymes in cold-mediated removal of embryonal dormancy has been discussed and compared with the role of these two factors in light-stimulated germination of dormant apple embryos, described earlier (Smoleńska and Lewak 1974).  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