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   155篇
  免费   3篇
  158篇
  2022年   2篇
  2021年   1篇
  2018年   1篇
  2017年   2篇
  2016年   2篇
  2015年   1篇
  2014年   5篇
  2013年   5篇
  2012年   6篇
  2011年   9篇
  2010年   4篇
  2009年   1篇
  2008年   5篇
  2007年   7篇
  2006年   7篇
  2005年   8篇
  2004年   3篇
  2003年   3篇
  2002年   5篇
  2001年   8篇
  2000年   1篇
  1999年   6篇
  1998年   3篇
  1996年   1篇
  1995年   1篇
  1992年   1篇
  1991年   7篇
  1990年   2篇
  1989年   4篇
  1986年   3篇
  1985年   3篇
  1984年   4篇
  1983年   2篇
  1982年   4篇
  1981年   1篇
  1980年   1篇
  1979年   4篇
  1978年   4篇
  1977年   2篇
  1976年   2篇
  1975年   5篇
  1974年   4篇
  1973年   2篇
  1972年   4篇
  1967年   2篇
排序方式: 共有158条查询结果,搜索用时 15 毫秒
61.
62.
63.

Background  

Macrophage migration inhibitory factor (MIF) has special pro-inflammatory roles, affecting the functions of macrophages and lymphocytes and counter-regulating the effects of glucocorticoids on the immune response. The conspicuous expression of MIF during human implantation and early embryonic development also suggests this factor acts in reproductive functions. The overall goal of this study was to evaluate Mif expression by trophoblast and embryo placental cells during mouse pregnancy.  相似文献   
64.
Bochkov AV 《Parazitologiia》2011,45(4):257-272
Host-parasite relationships of mammals and astigmatan mites (Acariformes: Astigmata) belonging to the parvorder Psoroptidia are analyzed. The absolute majority of mammal-associated psoroptidians belongs to the paraphyletic superfamily Sarcoptoidea. Mites of the family complex Psoroptidae (Lobalgidae, Psoroptidae, and Paracoroptinae) shifted from birds to placental mammals independently from each other. Mites of the family complex Sarcoptidae, including all other sarcoptoid families, derived from the common stalk of Psoroptidia independently from the Psoroptid complex. Mites of the sarcoptid complex shifted from nidicoly in mammalian nests to the permanent parasitism on these hosts. They are widely represented on both marsupial and placental mammals and are absent on Monotremata.  相似文献   
65.
Arthropod symbiotes of the Laotian rock-rat, Laonastes aenigmamus (Rodentia:Diatomyidae), from Laos are examined. This host is a member of Diatomyidae previously thought to have gone extinct >10 million yr ago. Permanent symbiotes are represented by 2 species, a new species of sucking louse, Polyplax sp., near rhizomydis (Phthiraptera:Polyplacidae), and a new species of fur mite, Afrolistrophorus sp., near maculatus (Acariformes:Listrophoridae). The temporary parasites are represented by 18 species, i.e., 1 mesostigmatan species, i.e., a new species of Androlaelaps near casalis (Parasitiformes:Laelapidae); immature stages of 2 tick species, Ixodes granulatus and Haemaphysalis sp. (Parasitiformes:Ixodidae); and a rich fauna of chiggers (Acariformes:Trombiculidae) comprising 8 genera and 15 species. It is hypothesized that this host completely lost its initial fauna of ectosymbiotes and that ancestors of the recorded symbiotes switched to this host from rodents of the superfamily Muroidea.  相似文献   
66.
Sensitivity of 56 streptococcal strains of group B to 12 antibiotics was studied with the method of dilution in a special solid medium for cultivation of streptococci and with the method of agar diffusion in the same medium. All the strains were found to be sensitive to chloramphenicol, ristomycin and erythromycin. The predominating majority of the strains were sensitive to beta-lactam antibiotics and lincomycin. All the strains were resistant to aminoglycoside antibiotics, such as streptomycin and gentamicin. More than 85 per cent of the strains were resistant to tetracycline. Strains with multiple resistance to 2-7 antibiotics were detected. Satisfactory correlation between the two methods was observed. It was shown to be clinically advisable to determine the sensitivity of streptococci of group B to beta-lactam antibiotics, erythromycin and lincomycin.  相似文献   
67.
Plasma Physics Reports - Dependences of kinetic and transport coefficients of electrons in helium on the electric field strength E reduced to the atomic concentration N in the E/N range from 15 to...  相似文献   
68.
In a maternity clinic the circulation of group B streptococci among the newborns, their mothers and the personnel was established during the period of 1982-1985. Group B streptococci were detected at different biotypes of newborns (the pharynx, the imbilical stump, external suditory meatus, nasal and oral mucosa, eyes and feces), their mothers (the vagina, the perianal area, breast milk, the pharynx, urine, the umbilical cord, amniotic fluid) and in the pharynx of the personnel. In this maternity clinic 15 combinations of type antigens were detected, two combinations (1a/c and 1 b/c) prevailing among them. These results confirmed earlier data concerning two possible ways of transferring infection to newborn infants: vertical, i.e. from the mother to the child during parturition, and nosocomial, i.e. from contaminated newborns or members of the personnel.  相似文献   
69.
A combined effect of thiophosphamide and dipin on chromosomes of unstimulated human lymphocytes was studied in experiments carried out thrice according to the scheme of a complete two-factor experiment. The exposure to the mutagens lasted for an hour, the concentrations being from 3.17 to 22.19 . 10-5 M. After washing a fresh medium with PHA was added to lymphocytes and then they were cultivated during 60 hrs. Both at separate and combined action of tested chemicals the effect observed in all the cytogenetic tests was not subjected to a linear dependence on the concentration of mutagens. With the change in the proportion between thiophosphamide and dipin, given that the summed number of their molecules was constant, the cytogenetic effect was directly proportional to the part of each mutagen in a combined treatment. The analysis of variance and regression analysis of the results obtained as well as the analysis of types of appearing chromosome aberrations and the analysis of distribution of breaks in cells at the combined action showed that, taking into account that the concentration dependences were not linear. the combined effect of thiophosphamide and dipin was additive, without any interaction of individual effects.  相似文献   
70.
The phenomenon of the parallel evolution is considered with the example of the myobiid mites (Acari: Prostigmata: Myobiidae) and the jerboas (Rodentia: Dipodoidea). According to recent phylogenetic studies of the superfamily Dipodoidea it is separated into 4 family: Allactagidae, Dipodidae, Zapodidae and Sminthidae (Shenbrot e. a., 1995). The myobiid mites of the subenus Dipodomyobia (11 species) of the genus Cryptomyobia are known as specific parasites associated with jerboas of the families Dipodidae and Allactagidae. One more species (Radfordia ewingi) considered as incertae sedis species within the genus Radfordia is found on the jerboas of the family Zapodidae. The myobiid mites are apparently absent on the members of the family Sminthidae. The reconstruction of phylogeny of the myobiid subgenus Dipodomyobia was carried out by the cladistic method (software PAUP 3.0 s). The analysis was based on 13 morphological characters. At the first step of analysis 42 parsimonious trees have been obtained. The strict consensus tree displays one distinct cluster, which incorporates mites of the allactaga species of group restricted to the jerboa family Allactagidae, and several plesions, species of which are usually refferred to as dipi species group and associated with the family Dipodidae (fig. 1). At the second step of analysis, two characters, which appeared as homoplasies at the first step of analysis were excluded, and one new characters (structure of male genital shield) was additionally included. Single cladogram obtained displays two general clusters and one plesion. The first cluster comprises the allactaga species group (parasites of Allactagidae). The second cluster incorporates the dipi species group, the parasites of subfamilies Dipodinae and Paradipodinae of Dipodidae). The plesion is represented by one species Cryptomyobia baranovae being a specific parasite of Salpingotus crassicauda (Cardiocraninae, Dipodidae). There is the high level congruence between the pattern of myobiid cladogram and jerboas phylogeny proposed by Shenbrot (1992) (fig. 2). The position of one species C. paradipi (the parasite of Paradipus ctenodactylus, single representative of subfam. Paradipodinae) does not fit to this phylogenetic system of the jerboas. This mite species belongs to the claster dipi. All others myobiid species of this group are the parasites of the subfamily Dipodinae. In the cladogram of jerboas, the subfam. Paradipodinae is a sister group of Cardiocraninae, but not of Dipodinae, as it is suggested by the parasitological data. If sinapomorphies in the node Paradipodinae--Cardiocraninae are not correct (as Shenbrot admitted), there would be a complete congruence between the phylogenetic pattern of myobiid and of jerboas. The general phylogeny of Dipodoidea based on citogenetical data was proposed by Vorontsov e. a. (1971). 3 families only were recognized within Dipodoidea: Zapodidae, Sminthidae and Dipodidae. The latter family included 3 subfamilies: Dipodinae, Cardiocraninae and Allactaginae. The version of the jerboa phylogeny proposed in the present paper based on parasitological data corresponds in general lines to the hypotesis of Vorontsov e. a. (1971). The myobiid mites are absent on Sminthidae, they are represented by one species incertae sedis on Zapodidae, and by the subgenus Dipodomyobia on others jerboas (Dipodidae sensu Vorontsov e. a.). According to the parasitological data, the subfamilies Dipodinae and Allactaginae are the sister groups, because the myobiid mites of the subgenus Dipodomyobia parazitise on the jerboas of these taxa only. The subfamily Paradipodinae (sensu Shenbrot) is a sister group for Dipodinae, as far as species C. paradipi is the sister species to other members of the dipi group. The subfamily Cardiocraninae is a sister group for the node Dipodinae-Paradipodinae and also should be included to Dipodidae, because the aberrant species C. baranovae is obviously related to the dipi species group.  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