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   109篇
  免费   7篇
  2021年   1篇
  2020年   2篇
  2019年   4篇
  2018年   2篇
  2017年   2篇
  2016年   4篇
  2015年   4篇
  2014年   5篇
  2013年   4篇
  2012年   9篇
  2011年   7篇
  2010年   4篇
  2009年   8篇
  2008年   7篇
  2007年   9篇
  2006年   7篇
  2005年   8篇
  2004年   8篇
  2003年   5篇
  2002年   2篇
  2001年   3篇
  2000年   1篇
  1999年   3篇
  1996年   1篇
  1995年   3篇
  1993年   1篇
  1991年   1篇
  1989年   1篇
排序方式: 共有116条查询结果,搜索用时 31 毫秒
1.
Digeneans of the family Campulidae occur exclusively in marine mammals, particularly in cetaceans. Their taxonomy is confused, being based on adult morphology only. We used a multivariate discriminant analysis of morphometric data to provide new evidence on the taxonomy of the Campulidae. Measurements of 217 specimens from 21 species of all seven genera of the family were taken. The percentage of specimens correctly assigned into their own species was 96.3%. The first three discriminant functions accounted for most of the variation between the species, which were grouped together in suprageneric groups along the first and the second function. The ordination pattern observed conforms partly with the established taxonomy of the Campulidae. Variation along the first discriminant function can be interpreted as a gradient of the vitelline extension and the maximum width to length ratio. This function separates three groups of species, corresponding to the Hunterotrematinae, Orthosplanchninae and Campulinae-Lecithodesminae. The last two subfamilies are separated along the second axis, the Lecithodesminae having longer bodies and suckers than the Campulinae. This study also provides some evidence at the generic and specific level.  相似文献   
2.
The taxonomy of marine species of the genus Diphyllobothrium, particularly those parasitic in cetaceans, is rather confused. During parasitological investigations of long-finned pilot whales Globicephala melas from waters off the Faroe Islands, five diphyllobothriid species were detected: Diphyllobothrium sp. (possibly D. polyrugosum), D. stemmacephalum, Diphyllobothrium sp. A, Diphyllobothrium sp. B and Diphyllobothriidae sp. D. stemmacephalum is reported for the first time from G. melas. The stituation regarding the taxonomy of Diphylobothrium species from cetaceans is briefly reviewed. It is concluded that the recent development of genetic techniques may be of great value in relation to clarifying the taxonomy of this group.  相似文献   
3.
The serum half‐life, biological activity, and solubility of many recombinant glycoproteins depend on their sialylation. Monitoring glycoprotein sialylation during cell culture manufacturing is, therefore, critical to ensure product efficacy and safety. Here a high‐throughput method for semi‐quantitative fingerprinting of glycoprotein sialylation using capillary isoelectric focusing immunoassay on NanoPro (Protein Simple) platform was developed. The method was specific, sensitive, precise, and robust. It could analyze 2 μL of crude cell culture samples without protein purification, and could automatically analyze from 8 samples in 4 h to 96 samples in 14 h without analyst supervision. Furthermore, its capability to detect various changes in sialylation fingerprints during cell culture manufacturing process was indispensable to ensure process robustness and consistency. Moreover, the changes in the sialylation fingerprints analyzed by this method showed strong correlations with intact mass analysis using liquid chromatography and mass spectrometry. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:235–241, 2016  相似文献   
4.

Background  

Flavonoids, one of the major groups of secondary metabolites, play important roles in the physiology, ecology and defence of plants. Their wide range of activities is the result of their structural diversity that encompasses a variety of functional group substitutions including hydroxylations. The aromatic hydroxylation at position 6 of flavonols is of particular interest, since it is catalyzed by a 2-oxoglutarate-dependent dioxygenase (ODD), rather than a cytochrome P450-dependent monooxygenase. ODDs catalyze a variety of enzymatic reactions implicated in secondary metabolite biosynthesis.  相似文献   
5.
Species of Lecithodesmus (Campulidae) occur almost exclusively in baleen whales throughout a wide geographical distribution. Other campulids occur only in odontocetes and, secondarily, in pinnipeds and the sea otter. Therefore, the ancestor of Lecithodesmus might have either cospeciated with mysticetes during the early divergence of mysticete and odontocete cetaceans or originated later via host switching. We evaluate both possibilities based on a phylogenetic analysis. The ND3 mitochondrial gene sequence of a species of Lecithodesmus was included in a previous partial molecular phylogeny of the Campulidae. Fasciola hepatica and Dicrocoelium dendriticum were used as outgroups. Maximum parsimony, neighbor-joining, and maximum likelihood methods indicated a nonbasal position of Lecithodesmus sp. in the tree, suggesting that the ancestor of Lecithodesmus colonized mysticetes from campulids of odontocetes. This result emphasizes the importance of host-switching processes in the development of the helminth fauna of marine vertebrates, as previously suggested.  相似文献   
6.
7.
Evidence suggests that the plasma membrane Ca2+-ATPase (PMCA), which is critical for maintaining a low intracellular Ca2+ concentration ([Ca2+]i), utilizes glycolytically derived ATP in pancreatic ductal adenocarcinoma (PDAC) and that inhibition of glycolysis in PDAC cell lines results in ATP depletion, PMCA inhibition, and an irreversible [Ca2+]i overload. We explored whether this is a specific weakness of highly glycolytic PDAC by shifting PDAC cell (MIA PaCa-2 and PANC-1) metabolism from a highly glycolytic phenotype toward mitochondrial metabolism and assessing the effects of mitochondrial versus glycolytic inhibitors on ATP depletion, PMCA inhibition, and [Ca2+]i overload. The highly glycolytic phenotype of these cells was first reversed by depriving MIA PaCa-2 and PANC-1 cells of glucose and supplementing with α-ketoisocaproate or galactose. These culture conditions resulted in a significant decrease in both glycolytic flux and proliferation rate, and conferred resistance to ATP depletion by glycolytic inhibition while sensitizing cells to mitochondrial inhibition. Moreover, in direct contrast to cells exhibiting a high glycolytic rate, glycolytic inhibition had no effect on PMCA activity and resting [Ca2+]i in α-ketoisocaproate- and galactose-cultured cells, suggesting that the glycolytic dependence of the PMCA is a specific vulnerability of PDAC cells exhibiting the Warburg phenotype.  相似文献   
8.
The chronology of post-larval development in S. chrysophrii, a polyopisthocotylean monogenean parasite of the gilthead seabream (Sparus aurata L.), was experimentally studied. It is compared with other species within the Microcotylidae and the Heteraxinidae, including an analysis of the changes in attachment and the growth rate. Gilthead seabreams infected by larvae of S. chrysophrii were killed periodically in order to collect the different developmental stages. Parasite total body length, haptor length, largest clamp width, and total number of clamps were recorded. Specimens of S. chrysophrii in culture conditions at 20°C became gravid after 26-30 days, with 37 pairs of clamps. The S. chrysophrii growth curve appears to be sigmoid with 3 growth periods (slow-fast-slow). The haptor of S. chrysophrii grows linearly with total body length, but the main contribution to total body length growth is that of the non-haptoral body. The relationship between number of clamps and total body length during development can be fitted to an exponential curve for all the reviewed species, i.e.: Microcotyle spinicirrus, Microcotyle donavini, Microcotyle gotoi, Microcotyle sebastis, Microcotyle hiatulae, Polylabroides multispinosus, Bivagina tai, Heteraxinoides xanthophilis, Heteraxine heterocerca, and Zeuxapta seriolae. The sequence of events was common for all of the species compared: terminal lappet is lost when about 15% of clamps were developed; primordia of testes at approximately 30% of clamps developed, and maturity (as first egg appearance) at about 65% of clamps developed.  相似文献   
9.
The tegumental structures of two types of tetraphyllidean plerocercoids and two types of merocercoids (Phyllobothrium delphini and Monorygma grimaldii) from Mediterranean striped dolphins, Stenella coeruleoalba, are described for the first time using scanning electron microscopy. The tegument of all of the specimens was fully covered with microtriches. Four basic types were found: filitriches, blade-like spinitriches of different sizes and shapes, cone-shaped spinitriches (with two parallel small projections of equal length at the apex), and crowned cylindrical spinitriches (with 6-7 small papillae forming a crown at the apex); the two latter types are newly described. The two types of plerocercoids had a similar morphology and distribution of microtriches; in addition, cilium-like projections appeared interspersed among the microtriches on the apical sucker, accessory suckers, and distal bothridial loculus. Merocercoids exhibited a greater variety of tegumental structures, especially on the distal bothridial loculus. Both merocercoid types had regularly spaced papillae or "buttons" on the accessory suckers and the distal bothridial loculus that were composed of a central cilium-like projection surrounded by numerous filitriches. However, crowned cylindrical spinitriches were specific to P. delphini and cone-shaped spinitriches were specific to M. grimaldii. Differences in the morphology and distribution of scolex microtriches of adult cestodes have been considered useful for species identification. A previous molecular study has suggested that P. delphini and M. grimaldii are actually different congeneric species. Our study has shown that significant differences in the morphology and distribution of microtriches occur between these species at the merocercoid stage.  相似文献   
10.
The communities of metazoan endoparasites of blue whiting, Micromesistius poutassou, in waters of north-west Spain were analysed and a geographical comparison made with other localities. Four hundred blue whiting collected in July 1999 and September 2000 were examined for parasites, excluding the head and gills. Six species were found: Anisakis simplex s.l. (L3), A. physeteris (L3), Hysterothylacium aduncum (L2 and L3), Stephanostomum lophii (metacercaria), S. pristis (adult), and Prosorhynchus crucibulum (metacercaria). The latter is a new host record, and A. physeteris is reported for the first time in blue whiting from the north-east Atlantic. Host gender was not a significant predictor of abundance of any helminth species, and host length was only weakly and positively related to the abundance of A. simplex. Infracommunities were species-poor, with 56% of fish harbouring only one parasite species, and 92% up to two species. Infracommunities were strongly dominated by A. simplex (389 fish) or S. lophii (6 fish). Fish length or gender, and the year of capture, did not affect species richness nor the degree of dominance. There were no significant pair-wise associations between species. Infracommunities were basically composed of several allogenic parasites with different life histories that converge in the blue whiting through the local food web. The parasite fauna of blue whiting in the study area was poor and distinctive compared with that of other localities in the north-east North Atlantic. These peculiarities might primarily be related to the composition of the local community of definitive hosts, although there might also be some influence of the geographical distribution of parasites.  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