全文获取类型
收费全文 | 378篇 |
免费 | 50篇 |
国内免费 | 1篇 |
出版年
2021年 | 3篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 16篇 |
2014年 | 17篇 |
2013年 | 16篇 |
2012年 | 20篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2009年 | 16篇 |
2008年 | 16篇 |
2007年 | 20篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 16篇 |
2003年 | 7篇 |
2002年 | 11篇 |
2001年 | 12篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 14篇 |
1997年 | 7篇 |
1996年 | 12篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 10篇 |
1978年 | 4篇 |
1977年 | 10篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有429条查询结果,搜索用时 93 毫秒
1.
2.
Intestinal microflora of the newborn rat as related to mammary, faecal, and vaginal Staphylococci strains isolated from the dam 总被引:2,自引:0,他引:2
To determine the relative importance of maternal microflora (faeces, vagina, and teats) in the contamination of newborn rats, strains of staphylococci from six different families (dam + litter) were isolated. These strains were identified, and by means of numerical profiles analyzed for their degree of similarity for each litter and (or) biotope. The staphylococci strains found in the gut of the newborn rat originated first from the teats and thereafter from the faeces. Concomitant observation of some identical strains, however, suggested a certain degree of similarity between these two maternal biotopes in this animal. 相似文献
3.
4.
5.
Stability of Bradyrhizobium japonicum Inoculants after Introduction into Soil 总被引:4,自引:3,他引:1 下载免费PDF全文
Brigitte Brunel Jean-Claude Cleyet-Marel Philippe Normand Rene Bardin 《Applied microbiology》1988,54(11):2636-2642
Bradyrhizobium japonicum USDA 125-Sp, USDA 138, and USDA 138-Sm had been used as inoculants for soybean (Glycine max (L.) Merr.) in soils previously free of B. japonicum. At 8 to 13 years after their release, these strains were reisolated from soil samples. A total of 115 isolates were obtained through nodules, and seven colonies were obtained directly by a serological method. The stability of the inoculants was confirmed by comparing the reisolated cultures with their respective parental strains which had been preserved by being lyophilized or stored on a yeast extract-mannitol agar slant at 4°C. Comparisons were made on morphological and serological characters, carbon compound utilization (8 tested), intrinsic antibiotic resistance (9 tested), and enzymatic activity (19 tested). Mucous and nonmucous isolates of serogroup 125 were analyzed for symbiotic effectiveness and restriction fragment hybridization with a DNA probe. Our data suggest that the B. japonicum inoculants have survived for up to 13 years in the soils without significant mutation except for two reisolates with a slightly increased kanamycin resistance level. 相似文献
6.
A human auto-immune antibody specifically recognizing initiator methionine tRNA from yeast and higher eucaryotes 总被引:2,自引:0,他引:2
J Sri-Widada H Graafland R Dietz C Brunel G Cathala P Jeanteur 《Biochemical and biophysical research communications》1986,139(1):275-280
Analysis of sera from 168 patients with autoimmune disorders revealed that one patient with Sj?gren's syndrome produced antibodies against deproteinized initiator methionine tRNA in addition to those against La protein. This anti-tRNAimet recognizes also tRNAimet from yeast but not from Phaseolus vulgaris chloroplasts (bean) or E. coli. It appears therefore that the epitope could be located in the TF loop in which an A residue in position 60 and the AUCG sequence are the only common features in yeast and human tRNAimet. 相似文献
7.
A comparative description of mitochondrial DNA differentiation in selected avian and other vertebrate genera 总被引:14,自引:1,他引:13
Levels of mitochondrial DNA (mtDNA) sequence divergence between species
within each of several avian (Anas, Aythya, Dendroica, Melospiza, and
Zonotrichia) and nonavian (Lepomis and Hyla) vertebrate genera were
compared. An analysis of digestion profiles generated by 13-18 restriction
endonucleases indicates little overlap in magnitude of mtDNA divergence for
the avian versus nonavian taxa examined. In 55 interspecific comparisons
among the avian congeners, the fraction of identical fragment lengths (F)
ranged from 0.26 to 0.96 (F = 0.46), and, given certain assumptions, these
translate into estimates of nucleotide sequence divergence (p) ranging from
0.007 to 0.088; in 46 comparisons among the fish and amphibian congeners, F
values ranged from 0.00 to 0.36 (F = 0.09), yielding estimates of P greater
than 0.070. The small mtDNA distances among avian congeners are associated
with protein-electrophoretic distances (D values) less than approximately
0.2, while the mtDNA distances among assayed fish and amphibian congeners
are associated with D values usually greater than 0.4. Since the
conservative pattern of protein differentiation previously reported for
many avian versus nonavian taxa now appears to be paralleled by a
conservative pattern of mtDNA divergence, it seems increasingly likely that
many avian species have shared more recent common ancestors than have their
nonavian taxonomic counterparts. However, estimates of avian divergence
times derived from mtDNA- and protein-calibrated clocks cannot readily be
reconciled with some published dates based on limited fossil remains. If
the earlier paleontological interpretations are valid, then protein and
mtDNA evolution must be somewhat decelerated in birds. The empirical and
conceptual issues raised by these findings are highly analogous to those in
the long-standing debate about rates of molecular evolution and times of
separation of ancestral hominids from African apes.
相似文献
8.
Methods for computing the standard errors of branching points in an evolutionary tree and their application to molecular data from humans and apes 总被引:23,自引:2,他引:21
Statistical methods for computing the standard errors of the branching
points of an evolutionary tree are developed. These methods are for the
unweighted pair-group method-determined (UPGMA) trees reconstructed from
molecular data such as amino acid sequences, nucleotide sequences,
restriction-sites data, and electrophoretic distances. They were applied to
data for the human, chimpanzee, gorilla, orangutan, and gibbon species.
Among the four different sets of data used, DNA sequences for an
895-nucleotide segment of mitochondrial DNA (Brown et al. 1982) gave the
most reliable tree, whereas electrophoretic data (Bruce and Ayala 1979)
gave the least reliable one. The DNA sequence data suggested that the
chimpanzee is the closest and that the gorilla is the next closest to the
human species. The orangutan and gibbon are more distantly related to man
than is the gorilla. This topology of the tree is in agreement with that
for the tree obtained from chromosomal studies and DNA-hybridization
experiments. However, the difference between the branching point for the
human and the chimpanzee species and that for the gorilla species and the
human-chimpanzee group is not statistically significant. In addition to
this analysis, various factors that affect the accuracy of an estimated
tree are discussed.
相似文献
9.
10.
J Temsamani C Alibert J Tazi M Rucheton J P Capony P Jeanteur G Cathala C Brunel 《Journal of molecular biology》1989,206(3):439-449
Native small nuclear ribonucleoproteins (snRNPs) purified by several conventional procedures or reconstituted in vitro have no ribonuclease activity. However, when these same snRNPs are centrifuged in cesium chloride gradients at low [Mg2+] and in the presence of sarkosyl, an endoribonuclease is unmasked at the density of core particles (i.e. containing only the set of low molecular weight proteins common to all snRNPs), while an inhibitory component is released in soluble form. The nature of this inhibitor was not further investigated and the molecular events underlying this inhibition/activation process remained only a matter of speculation. On the other hand, evidence was obtained that the nuclease activity is carried by B-B' on the basis of its comigration with B-B' as well as with two of their cleavage products after SDS/polyacrylamide gel electrophoresis of snRNP proteins. One was identified by a B-B'-specific monoclonal antibody. Another one, especially prominent and migrating between D and E core proteins, was identified as the N-terminal half of B-B' by microsequence analysis. Although tightly associated with core snRNPs, the activity is not dependent upon the presence of an snRNA. For the time being, the functional significance of this nuclease remains entirely elusive. 相似文献