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排序方式: 共有161条查询结果,搜索用时 15 毫秒
1.
David Bruce Conn Sarah E. Simpson Dan Minchin Frances E. Lucy 《Biological invasions》2008,10(2):149-156
Samples of Dreissena polymorpha were collected at several sites along the River Shannon navigation in Ireland, to determine the occurrence and distribution
of their obligate host-specific commensalistic ciliate, Conchophthirus acuminatus, in this newly invaded region. Mussels collected by various methods were fixed immediately in 75% ethanol, in which they
were later dissected under a stereoscopic microscope, beginning with thorough flushing of the mantle cavity and removal of
the gills. One ml of sediment flushed from the mantle cavity and dissection residue of each mussel was examined under a compound
light microscope using brightfield, phase-contrast, and differential-interference-contrast optics. Of 180 mussels examined,
125 (69.44%) harbored C. acuminatus. The ciliates were invariably well fixed and easily identifiable in all preparations. Mean sampling intensity for infected
mussels was 8.47 ciliates per ml of sediment. Both prevalence and sampling intensity varied between sites, but no pattern
was discernible. The present results are consistent with other reports of C. acuminatus being the most widespread and abundant symbiont of D. polymorpha throughout Europe, often occurring where no other symbionts occur. Its occurrence in Ireland indicates introduction of the
mussels as adults, since planktonic veliger larvae are not known to harbor ciliates. Following similar reasoning, it is possible
that the earlier North American invasion by D. polymorpha included only veligers, since C. acuminatus has not been found on that continent. Using these simple and quick methods, the ciliates could be easily identified and counted
to give general comparative data among sites regarding intensity and prevalence. Thus, this method has promise for future
efforts to obtain basic information rapidly in newly invaded systems. 相似文献
2.
MIKIO SUHAMA 《The Journal of eukaryotic microbiology》1990,37(5):344-352
ABSTRACT. In the ciliate Glaucoma scintillans , the process of transformation of unbalanced homopolar doublets to singlets was investigated. Cells were fixed 1–3 days after inoculation and impregnated with silver according to the Chatton-Lwoff technique. The two oral apparatuses (OAs) approached each other partly due to a loss of ciliary rows in one of the two components (semicells) consisting of a doublet. The contractile vacuole pore (CVP) in the narrow semicell (sc1) was lost at an early stage of regulation, while the position of CVP in the broad semicell (sc2) shifted toward the right after the loss of sc1. The sc1 of 20 row-intervals in breadth was a transition point above which the sc1 was able to persist for awhile, and beneath which it was actively lost. There was no evidence for an independent effect of sc2 on the transformation of doublets to singlets. In cell division, an additional reversed oral primordium (sOP) was formed in unbalanced doublets, usually within a narrow sc1 of 11–20 row-intervals. The position of the sOP was generally 4–6 row-intervals distant from the right side of the oral meridian (OM1) with the cell's left OA. Most of the doublets with an sOP lacked an oral primordium in the OM1. No mature triplet with 2 normal OAs and an abnormal OA was found in these preparations. The pathway of regulation, the movement of the CVP, and the formation of an sOP are discussed. 相似文献
3.
JOHN A. KLOETZEL 《The Journal of eukaryotic microbiology》1991,38(4):392-401
Morphogenesis of the ciliate cortex has been viewed as an attractive model system for studying the mechanisms behind the ordered assembly of subcellular structure. Based on the assumption that identifying protein components of the cortex would facilitate the study of cortical assembly, I have produced a number of monoclonal antibodies directed against components of the cortex of Euplotes aediculatus. Several of these antibodies react with the proteins comprising the alveolar plates. These thin polygonal scales, each enclosed within a flattened membranous sac (alveolus) just beneath the cell membrane, tightly abut in a confluent monolayer that appears to lend form and rigidity to the Euplotes cell cortex. Reactivity and specificity of these monoclonal antibodies for the alveolar plates was shown by immunofluorescence staining of whole-cell preparations and of cryosections, and by immuno-gold staining of thin sections by electron microscopy. On immunoblots of SDS-PAGE separated whole-cell extracts, the plate proteins are revealed as two to three closely spaced bands centered at an Mr of 97 kDa, and a larger relative at 125 kDa. Comparative peptide mapping reveals that the members of the 97-kDa protein cluster are closely related. However, the 125-kDa polypeptide varies significantly from the 97-kDa members, and hence is not likely a synthetic precursor. Because bands of these Mr values are prominent in Coomassie blue-stained gels of whole-cell extracts, and are greatly enriched in purified cortical preparations, they likely represent the major proteins comprising the alveolar plates of E. aediculatus. I have proposed the name platein for this family of proteins. 相似文献
4.
采用ISSR分子标记技术,尝试对四种五株纤毛虫(褶累枝虫(Epistylis plicatilis)、绿草履虫(Paramecium bursaria)、多态喇叭虫(Stentor polymorphus)、嗜热四膜虫BF1株(Tetrahymena thermophilaBF1)和嗜热四膜虫BF5株(T.ther-mophilaBF5))进行遗传关系研究。用13个ISSR引物对五株纤毛虫进行扩增,六个ISSR引物获得多态片段。根据Nei s遗传距离矩阵构建了五株纤毛虫的遗传关系树状图。UPGMA,NJ聚类图表明:两株嗜热四膜虫最先聚在一起;其次是褶累枝虫和多态喇叭虫聚在一起,然后再与嗜热四膜虫聚在一起;咽膜亚纲的绿草履虫形成独立的一枝。结果显示:①缘毛亚纲纤毛虫可能是寡膜纲中较独特的一个类群,建议提升缘毛亚纲纤毛虫的分类地位;②缘毛亚纲褶累枝虫与膜口亚纲嗜热四膜虫的亲缘关系近于咽膜亚纲绿草履虫,在寡膜纲中绿草履虫处于原始地位;③五株纤毛虫基因组中均含有微卫星DNA序列:(GTG)4(、GACA)4(、AG)8(、CAA)6和(GAA)6。 相似文献
5.
6.
In the ciliate Euplotes raikovi, two specific isoforms of cAMP-dependent phosphodiesterases were identified, one in the soluble and the other in the particulate fraction of the cell. Their activity was shown to be stimulated by Mg2+, insensitive to Ca2+ and cGMP, and scarcely inhibited by theophylline and 3-isobutyl-1-methyl-xanthine. They appear to be related to some phosphodiesterases of class II of other unicellular organisms in their biochemical features, and their enzymatic activity is up-regulated by elevation of intracellular cAMP level similarly to PDE-4 isoforms of mammals. 相似文献
7.
D. WAYNE COATS SUNJU KIM TSVETAN R. BACHVAROFF SARA M. HANDY CHARLES F. DELWICHE 《The Journal of eukaryotic microbiology》2010,57(6):468-482
ABSTRACT. The dinoflagellate Tintinnophagus acutus n. g., n. sp., an ectoparasite of the ciliate Tintinnopsis cylindrica Daday, superficially resembles Duboscquodinium collini Grassé, a parasite of Eutintinnus fraknoii Daday. Dinospores of T. acutus are small transparent cells having a sharply pointed episome, conspicuous eyespot, posteriorly positioned nucleus with condensed chromosomes, and rigid form that may be supported by delicate thecal plates. Dinospores attach to the host via a feeding tube, losing their flagella, sulcus, and girdle to become spherical or ovoid cells. The trophont of T. acutus feeds on the host for several days, increasing dramatically in size before undergoing sporogenesis. Successive generations of daughter sporocytes are encompassed in an outer membrane or cyst wall, a feature not evident in trophonts. Tintinnophagus acutus differs from D. collini in host species, absence of a second membrane surrounding pre‐sporogenic stages, and failure to differentiate into a gonocyte and a trophocyte at the first sporogenic division. Phylogenetic analyses based on small subunit (SSU) ribosomal DNA (rDNA) sequences placed T. acutus and D. collini in the class Dinophyceae, with T. acutus aligned loosely with Pfiesteria piscicida and related species, including Amyloodinium ocellatum, a parasite of fish, and Paulsenella vonstoschii, a parasite of diatoms. Dubosquodinium collini nested in a clade composed of several Scrippsiella species and Peridinium polonicum. Tree construction using longer rDNA sequences (i.e. SSU through partial large subunit) strengthened the placement of T. acutus and D. collini within the Dinophyceae. 相似文献
8.
BYUNG CHEOL CHO JONG SOO PARK KUIDONG XU JOONG KI CHOI 《The Journal of eukaryotic microbiology》2008,55(5):417-426
ABSTRACT. A new ciliate, Trimyema koreanum n. sp., isolated from hypersaline water (salinity of 293‰) from a solar saltern in Korea, was investigated using live observation, protargol impregnation, and gene sequencing. Trimyema koreanum is about 30 × 13 μm in vivo, has usually 23 longitudinal ciliary rows forming two distinct ciliary girdles visible both in vivo and in protargol impregnation. A third indistinct ciliary girdle as well as a girdle of mucocysts is distinguishable only in impregnated cells. We suggest T. koreanum as a new species, differing from the most similar species, T. marinum, by the presence of two distinct ciliary girdles (T. marinum usually has six ciliary girdles clearly visible in living cells and three anterior spirals that encircle the cell completely). Although the number of known 18S rRNA sequences in the genus Trimyema was limited, the Trimyema group including T. koreanum forms a strong clade. The phylogenetic position confirms that the isolate belongs to the genus Trimyema and is different from previously sequenced species. Trimyema koreanum is able to consume both prokaryotes and small eukaryotes (specifically, the alga Dunaliella sp.). 相似文献
9.
10.
Abdel-Azeem S. Abdel-Baki Mohamed M. Gewik Saleh Al-Quraishy 《Saudi Journal of Biological Sciences》2014,21(6):520-523
The present study was carried out as part of an ongoing general survey seeking to uncover protozoan parasites infecting cultured tilapia in the central region of Saudi Arabia. In the sample of 400 specimens of tilapia (Oreochromis niloticus) 30 were infested with Ambiphrya ameiuri simultaneously with Vorticella sp. Morphometric criteria were used to describe and identify these species and this study presents the first records of these species among cultured fish in Saudi Arabia. 相似文献