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   125篇
  免费   6篇
  2020年   1篇
  2019年   6篇
  2018年   1篇
  2017年   8篇
  2016年   5篇
  2015年   6篇
  2014年   9篇
  2013年   8篇
  2012年   10篇
  2011年   15篇
  2010年   7篇
  2009年   6篇
  2008年   8篇
  2007年   6篇
  2006年   8篇
  2005年   1篇
  2004年   7篇
  2003年   2篇
  2002年   5篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1995年   1篇
  1993年   1篇
  1992年   1篇
  1985年   1篇
  1976年   1篇
  1952年   1篇
排序方式: 共有131条查询结果,搜索用时 62 毫秒
1.
2.
3.
Three new species of the streptaxid snail genus Perrottetia are described from north and northeastern Thailand, Perrottetia aquilonaria sp. n., Perrottetia dermapyrrhosa sp. n. and Perrottetia phuphamanensis sp. n. Each species is endemic to a single or a few limestone mountain ranges. The species are characterized by the morphology of their genital organs, as well as by shell characters. Perrottetia aquilonaria sp. n. has a club shaped distal penis and large penial hooks are present and penial papillae cover almost the entire penial hook portion; adjacent areas possess low reticulated folds. Perrottetia dermapyrrhosa sp. n. has a long genital atrium and the penial sheath is about two-thirds of the penis length. Penial hooks are long, scattered and sunken into deep ovate hollows; vaginal hooks are present. Perrottetia phuphamanensis sp. n. has a rounded and protruded shell periphery. The aperture is subcircular, peristome is thick and the second parietal lamella is adjacent to the first parietal lamella; a basal lamella is the smaller than in the other Thai species.  相似文献   
4.
Abstract

The structural and dynamical properties of the complete full-length structure of HIV-1 integrase were investigated using Molecular Dynamics approach. Simulations were carried out for the three systems, core domain only (CORE), full-length structure without (FULL) and with a Mg2+ (FULL+ION) in its active site, aimed to investigate the difference in the molecular properties of the full-length models due to their different construction procedures as well as the effects of the two ends, C- and N-terminal, on those properties in the core domain. The full-length structure was prepared from the two experimental structures of two-domain fragment. The following properties were observed to differ significantly from the previous reports: (i) relative topology formed by an angle between the three domains; (ii) the cavity size defined by the catalytic triad, Asp64, Asp116, and Glul52; (iii) distances and solvation of the Mg2+; and (iv) conformation of the catalytic residues. In addition, the presence of the two terminal domains decreases the mobility of the central core domain significantly.  相似文献   
5.
6.
The teleomorph of Aquaphila albicans was discovered on submerged wood collected in Thailand. Its black, soft-textured, setose ascomata, bitunicate asci and hyaline to pale brown, multiseptate ascospores indicated an affinity to Tubeufiaceae (Dothideomycetes). After morphological or molecular comparisons with related species in Tubeufia, Acanthostigma and Taphrophila, it is described and illustrated as a new species, T. asiana Sivichai & K.M. Tsui, sp. nov. Finding this Tubeufia teleomorph was surprising, given the falcate conidia of its A. albicans anamorph, which superficially resemble the conidia of Fusarium and not the coiled, helicosporous conidia of other species in Tubeufiaceae. We assessed the phylogenetic relationships of A. albicans-T. asiana with ribosomal sequences from SSU and ITS and partial LSU regions by parsimony and Bayesian analysis. An initial set of 40 taxa representing a wide range of ascomycete families and their SSU sequences from GenBank showed A. albicans-T. asiana to be nested within the Tubeufiaceae with 100% bootstrap support. Their placement was inferred with ITS and partial LSU ribosomal sequences. The nearly identical ITS sequences of two isolates of A. albicans and one isolate of Tubeufia asiana united these fungi as a monophyletic group with 100% bootstrap support and further nested them, with 88% bootstrap support, in a clade containing Helicoon gigantisporum and Helicoma chlamydosporum. This is the first molecular phylogenetic study to place a nonhelicosporous species within the Tubeufiaceae and to show that helical conidia were lost at least once within the family.  相似文献   
7.
In January and March of 2005, we conducted surveys of long-tailed macaques at Piak Nam Yai Island, Laem Son National Park (9 degrees N 34-35', 98 degrees E 28'), Ranong Province, situated in southern Thailand. Two of the three troops of long-tailed macaques found on the island were observed using axe-shaped stones to crack rock oysters, detached gastropods (Thais tissoti, Petit, 1852), bivalves (Gafrarium divaricatum, Gmelin, 1791), and swimming crabs (Thalamita danae, Stimpson, 1858). They smashed the shells with stones that were held in either the left or right hand, while using the opposite hand to gather the oyster meat. Some monkeys used both hands to handle the stones. According to Matsuzawa's 1996 hierarchical classification of tool usage (levels 0-3), the tool usage by Thai long-tailed macaques could be characterized as either level 1 (cracking rock oysters with stones) or level 2 (cracking drifting mollusks and crabs with stones by placing them on a rock). Our discovery of stone-tool usage by Thai long-tailed macaques provides a new point of reference for discussions regarding the evolution of tool usage and the material culture of primates.  相似文献   
8.
The large genus Orthomorpha is rediagnosed and is shown to currently comprise 51 identifiable species ranging from northern Myanmar and Thailand in the Northwest to Lombok Island, Indonesia in the Southeast. Of them, 20 species have been revised and/or abundantly illustrated, based on a restudy of mostly type material; further 12 species are described as new: Orthomorpha atypicasp. n., Orthomorpha communissp. n., Orthomorpha isarankuraisp. n., Orthomorpha picturatasp. n., Orthomorpha similanensissp. n., Orthomorpha suberectasp. n., Orthomorpha tuberculiferasp. n.,Orthomorpha subtuberculiferasp. n. and Orthomorpha latitergasp. n., all from Thailand, as well as Orthomorpha elevatasp. n.,Orthomorpha spiniformissp. n. and Orthomorpha subelevatasp. n., from northern Malaysia. The type-species Orthomorpha beaumontii (Le Guillou, 1841) is redescribed in due detail from male material as well, actually being a senior subjective synonym of Orthomorpha spinala (Attems, 1932), syn. n. Two additional new synonymies are proposed: Orthomorpha rotundicollis (Attems, 1937) = Orthomorpha tuberculata (Attems, 1937), syn. n., and Orthomorpha butteli Carl, 1922 = Orthomorpha consocius Chamberlin, 1945, syn. n., the valid names to the left. All species have been keyed and all new and some especially widespread species have been mapped. Further six species, including two revised from type material, are still to be considered dubious, mostly because their paraterga appear to be too narrow to represent Orthomorpha species. A new genus, Orthomorphoidesgen. n., diagnosed versus Orthomorpha through only moderately well developed paraterga, coupled with a poorly bi- or trifid gonopod tip, with at least some of its apical prongs being short spines, is erected for two species: Orthomorpha setosus (Attems, 1937), the type-species, which is also revised from type material, and Orthomorpha exaratus (Attems, 1953), both comb. n. ex Orthomorpha.  相似文献   
9.
Tuberculosis (TB) remains a major health problem worldwide. Understanding the interactions between the surface components of Mycobacterium tuberculosis (Mtb), the main causative agent of TB, with host immune response will be critical for developments of effective treatments and prevention of TB. Chemically defined mimics of the bacterial envelope components serve as important tools for biological studies of the bacterial interactions with mammalian hosts. We report here a rapid synthetic approach utilizing mannosyl tricyclic orthoesters as monomers for regio- and stereo-controlled polymerizations to generate α(1–6) mannopyranan—the backbone of lipomannan. The polymerizations generated multiple glycosidic bonds in a single chemical transformation in regio- and stereo-selective manners. TMSOTf is the optimum catalyst to promote the selective and high yielding polymerization when compared with other Lewis acids. In addition, the monomers 3,4-O-benzyl-β-d-mannopyranose 1,2,6-orthobenzoate (1) and 3,4-O-benzyl-β-d-mannopyranose 1,2,6-orthopivalate (2) can be synthesized in multiple-gram scale and in a rapid fashion. Characterizations by GPC and NMR indicate the identity of α(1–6) mannopyranan with DPn (degree of polymerization) = 20.  相似文献   
10.
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