全文获取类型
收费全文 | 297篇 |
免费 | 19篇 |
国内免费 | 1篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 7篇 |
2014年 | 11篇 |
2013年 | 23篇 |
2012年 | 22篇 |
2011年 | 13篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 16篇 |
2007年 | 21篇 |
2006年 | 6篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 11篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1958年 | 1篇 |
1951年 | 1篇 |
1950年 | 1篇 |
1945年 | 1篇 |
1944年 | 1篇 |
1924年 | 1篇 |
排序方式: 共有317条查询结果,搜索用时 15 毫秒
1.
2.
MAJOR CLADES OF THE ANGIOSPERMS 总被引:2,自引:0,他引:2
ROLF DAHLGREN KÅRE BREMER 《Cladistics : the international journal of the Willi Hennig Society》1985,1(4):349-368
Abstract— Our knowledge of fundamental angiosperm interrelationships is still very incomplete. The absence of a narrowly circumscribed gymnosperm outgroup, ideally the sister group, makes character evaluation, necessary for a cladistic analysis, difficult. According to current views the superorder Magnoliiflorae with a number of other groups, for example the monocotyledons, may represent a complex of families near the base of the angiosperms. Interrelationships of groups within the monocotyledons are much better understood than those between groups within the dicotyledons. A cladogram of monocotyledon orders based on earlier work by R. Dahlgren, H. T. Clifford, and F. N. Rasmussen is presented. A data matrix for a sample of the angiosperms with 61 characters for 49 taxa, mostly magnoliifloran and related families, is presented. The characters are polarized mainly according to the current view that the primitive angiosperm morphotype is a woody dicotyledon with strobiloid flowers. As an alternative the matrix is adjusted following W. C. Burger's conjecture that the primitive angiosperm was a herbaceous monocotyledon with trimerous flowers. Both matrices were run in a computerized parsimony analysis, resulting in numerous equally parsimonious solutions. This result is illustrative of the great homoplasy in the available character information, and also of how little actually is known about fundamental angiosperm interrelationships or phylogeny. 相似文献
3.
Assignment of orthologous relationships among mammalian alpha-globin genes by examining flanking regions reveals a rapid rate of evolution 总被引:1,自引:0,他引:1
In order to study the relationships among mammalian alpha-globin genes, we
have determined the sequence of the 3' flanking region of the human alpha 1
globin gene and have made pairwise comparisons between sequenced
alpha-globin genes. The flanking regions were examined in detail because
sequence matches in these regions could be interpreted with the least
complication from the gene duplications and conversions that have occurred
frequently in mammalian alpha-like globin gene clusters. We found good
matches between the flanking regions of human alpha 1 and rabbit alpha 1,
human psi alpha 1 and goat I alpha, human alpha 2 and goat II alpha, and
horse alpha 1 and goat II alpha. These matches were used to align the
alpha-globin genes in gene clusters from different mammals. This alignment
shows that genes at equivalent positions in the gene clusters of different
mammals can be functional or nonfunctional, depending on whether they
corrected against a functional alpha-globin gene in recent evolutionary
history. The number of alpha-globin genes (including pseudogenes) appears
to differ among species, although highly divergent pseudogenes may not have
been detected in all species examined. Although matching sequences could be
found in interspecies comparisons of the flanking regions of alpha- globin
genes, these matches are not as extensive as those found in the flanking
regions of mammalian beta-like globin genes. This observation suggests that
the noncoding sequences in the mammalian alpha-globin gene clusters are
evolving at a faster rate than those in the beta-like globin gene clusters.
The proposed faster rate of evolution fits with the poor conservation of
the genetic linkage map around alpha-globin gene clusters when compared to
that of the beta-like globin gene clusters. Analysis of the 3' flanking
regions of alpha-globin genes has revealed a conserved sequence
approximately 100-150 bp 3' to the polyadenylation site; this sequence may
be involved in the expression or regulation of alpha-globin genes.
相似文献
4.
INTRODUCTI0NThedifferentiati0nofcelIsalongthemonocyte-macr0phagepathwayandthesig-nalsinvo1vedinthesecel1sacquiringtheabilitytokilltum0rcellsarenotfllllyundersto0d.Wehavebeenstudingamoleculewhichappearst0beanimportantmemberofthecytokinenetworkinvo1vedintheregulati0nmonocyteactivation.ThiscytokinetermedP48wasisolatedfr0mthehllmannullcellleukemiacell1ineReh.IthasbeenpurifiedtohomogeneityandfOundtobedistinctfrominterferongamma,col0nystimulatingfactors(CSFs)andTNFalphaalldbeta[1,2].Func-ti… 相似文献
5.
Differential tyrosine phosphorylation of the IFNAR chain of the type I interferon receptor and of an associated surface protein in response to IFN-alpha and IFN-beta. 总被引:11,自引:3,他引:8
下载免费PDF全文
![点击此处可从《The EMBO journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
C Abramovich L M Shulman E Ratovitski S Harroch M Tovey P Eid M Revel 《The EMBO journal》1994,13(24):5871-5877
6.
Tore Eid 《Biotechnic & histochemistry》1993,68(4):189-192
Hydrophobic adhesive tape was used to produce miniature wells on microscope slides for staining several sections of tissue with minimal amounts of cytochemical reagents. The wells could be tailored to individual specifications and the method allowed coverslips to be mounted close to the sections using either aqueous or xylene based mounting media. This method was especially useful for multiple immunolabelling of serial semithin cryosections. 相似文献
7.
Moxifloxacin and ofloxacin are two broad-spectrum quinolone antibiotics. They are among the most widely used antibiotics, at this time, applied to control the COVID-19 pandemic. Hydroxychloroquine is an FDA-approved drug for the treatment of COVID-19. This work describes a simple, green, selective, and sensitive spectrofluorimetric method for the assay of moxifloxacin and ofloxacin in the presence of hydroxychloroquine, two co-administered mixtures used in the treatment of hospital-acquired pneumonia in patients with COVID-19. Simultaneous assay of hydroxychloroquine and moxifloxacin was carried out in methanol using a direct spectrofluorimetric method (method I) at 375 and 550 nm, respectively, after excitation at 300 nm. The direct spectrofluorimetric assay was rectilinear over concentration ranges 50.0–400.0 and 300.0–2500.0 ng/ml for hydroxychloroquine and moxifloxacin, respectively, with limits of detection (LOD) of 6.4 and 33.64 ng/ml and limits of quantitation (LOQ) of 19.4 and 102.6 ng/ml, respectively, for the two drugs. The assay for hydroxychloroquine and ofloxacin was carried out by measuring the first derivative synchronous amplitude for hydroxychloroquine at the zero crossing point of ofloxacin and vice versa at Δλ = 140 nm (method II). Hydroxychloroquine was measured at 266 nm, while ofloxacin was measured at 340 nm over the concentration range 4–40 ng/ml for hydroxychloroquine and 200–2000 ng/ml for ofloxacin with LOD of 0.467 and 25.3 ng/ml and LOQ of 1.42 and 76.6 ng/ml, respectively, for the two drugs. The two methods were validated following International Conference on Harmonization guidelines and were applied to the analysis of the two drugs in plasma with good percentage recoveries (109.73–93.17%). 相似文献
8.
Four homologues of pepstatin, the potent but poorly soluble inhibitor of aspartic proteinases, were synthesized by coupling to the C-terminus of the natural pentapeptide the following amino acid residues: L-arginine methyl ester, L-aspartic acid, L-glutamic acid and the dipeptide L-aspartyl-L-arginine. The peptide-coupling reagent we used, benzotriazolyloxytris(dimethylamino)phosphonium hexafluorophosphate, allowed us to obtain readily pure pepstatin homologues with high yields (60-83%). Pepstatylarginine methyl ester and pepstatylglutamic acid were about one order of magnitude more water-soluble than pepstatin. The four homologues and pepstatin were tested in vitro as inhibitors for highly purified pig and human renins acting on the N-acetyltetradecapeptide substrate. The 50% inhibitory concentrations (IC50) of the homologues were ranged from 0.01 to 1 microM against porcine renin at pH 6.0 (pepstatin IC50 approximately 0.32 microM) and from 5.8 to 41 microM against human renin at pH 6.5 (pepstatin IC 50 approximately 17 microM). By three different graphical methods we showed that pepstatin and the four homologues behaved as competitive inhibitors for porcine renin. The most potent inhibitors were pepstatylaspartic acid and pepstatylglutamic acid, with inhibitory constants respectively 2- and 10-fold smaller than that of pepstatin. By coupling glutamic acid to pepstatin, the ratio solubility/Ki was increased by two orders of magnitude. 相似文献
9.
Julien Giron-Michel Sandy Azzi Silvano Ferrini Salem Chouaib Giovanni Camussi Pierre Eid Bruno Azzarone 《Cytokine & growth factor reviews》2013,24(1):13-22
Experiments in IL-15?/? and IL-15Rα?/? mice show that intra-renal IL-15, through IL-15Rα behaves as an epithelial survival factor. Recent data highlight new functions of IL-15 in renal homeostasis mediated by IL-15Rγ (CD132). Indeed, in CD132+ renal epithelial tubular cells IL-15 preserves E-cadherin expression inhibiting epithelial-mesenchymal transition (EMT). By contrast, during allograft rejection, the increased intra-graft IL-15 expression favors tubular destruction facilitating the intraepithelial recruitment of CD8 T cells expressing the E-cadherin ligand CD103. In renal cancer, loss of CD132 by epithelial cells defines a tumoral microenvironment where IL-15 triggers E-cadherin down-regulation and EMT. Finally, in CD132+ renal cancer stem cells IL-15 induces the generation of non-tumorigenic epithelial cells sensitive to cytotoxic drugs. These findings are discussed in the light of IL-15-based immunotherapy for renal cancer. 相似文献
10.
Dani?l P Melters Keith R Bradnam Hugh A Young Natalie Telis Michael R May J Graham Ruby Robert Sebra Paul Peluso John Eid David Rank José Fernando Garcia Joseph L DeRisi Timothy Smith Christian Tobias Jeffrey Ross-Ibarra Ian Korf Simon WL Chan 《Genome biology》2013,14(1):R10