全文获取类型
收费全文 | 133篇 |
免费 | 9篇 |
国内免费 | 2篇 |
出版年
2023年 | 1篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 13篇 |
2009年 | 13篇 |
2008年 | 8篇 |
2007年 | 1篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 4篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1975年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有144条查询结果,搜索用时 15 毫秒
91.
92.
FLORÉAL SOLÉ EMMANUEL GHEERBRANT MBAREK AMAGHZAZ BAÂDI BOUYA 《Zoological Journal of the Linnean Society》2009,156(4):827-846
We report here the new ‘creodont’ Lahimia selloumi gen. et sp. nov. from the late Palaeocene of the Ouled Abdoun Basin (Morocco) as the oldest known Hyaenodontidae with Tinerhodon from the Ouarzazate Basin (Morocco). By contrast to Tinerhodon, Lahimia is unexpectedly derived. Most of its specializations, such as the shortening of the anterior dentition (e.g. loss of P1) and the talonid reduction and simplification, are strikingly shared with Boualitomus from the Ypresian of the Ouled Abdoun Basin, and are distinctive from other hyaenodontids, including ‘proviverrines’. They are interpreted as synapomorphies evidencing a precociously specialized early African hyaenodontid lineage. Although Lahimia and Boualitomus remain known only by the lower dentition, their relationships with Koholia are suggested by comparison of their molar occlusal pattern. Lahimia and Boualitomus are referred to the Koholiinae, which is representative of an old African endemic lineage, as initially recognized. This remarkable lineage is characterized by synapomorphies of Lahimia and Boualitomus, and also by a shared original prevallum/postvallid shearing. The discovery of Lahimia provides direct evidence for the antiquity of the African evolution of the Hyaenodontidae. This is in agreement with an African origin of the Hyaenodontidae, and with the probable diphyletism of the ‘Creodonta’. Lahimia and the Koholiinae, as well as the diversity of the first Laurasian hyaenodontid lineages, emphasize our poor knowledge of the striking early African hyaenodontid radiation. 相似文献
93.
RAFAEL L. RODRÍGUEZ NOORIA AL‐WATHIQUI 《Biological journal of the Linnean Society. Linnean Society of London》2012,105(1):187-196
Developmental plasticity may promote divergence by exposing genetic variation to selection in novel ways in new environments. We tested for this effect in the static allometry (i.e. scaling on body size) of traits in advertisement signals, body and genitalia. We used a member of the Enchenopa binotata species complex of treehoppers – a clade of plant‐feeding insects in which speciation is associated with colonization of novel environments involving marked divergence in signals, subtle divergence in body size and shape, and no apparent divergence in genitalia. We found no change in mean allometric slopes across environments, but substantial genetic variation and genotype × environment interaction (G × E) in allometry. The allometry of signal traits showed the most genetic variation and G × E, and that of genitalia showed the weakest G × E. Our findings suggest that colonizing novel environments may have stronger diversifying consequences for signal allometry than for genitalia allometry. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 187–196. 相似文献
94.
In the present study, bee colonies were smoked with tobacco smoke in order to evaluate the monthly changes in the numbers of worker bees, the infestation rates of worker bees and queens with bee lice, and the annual average honey production per colony. In July of each year, 12 colonies were smoked with tobacco smoke; the remaining hives not smoked with tobacco smoke served as the control. The results indicated that the applications of tobacco smoke during July gave rise to an impressive reduction in the Braula infestation rate on workers (below 1.8%) and reduced the amount of bee lice on the queen to zero throughout the 2–3 months following smoke treatment. In the colonies not treated with smoke, the Braula infestation rates on worker bees started to increase in May and continued to increase constantly during the rest of year, reaching maximum infestation rates of 28.2% and 33.8% in December, with an average of 15 and 17 lice per queen in November in the first and second years, respectively. Worker bee populations peaked in April and July of each year in both treatments. The average honey production per colony was significantly higher in the colonies treated with smoke than those that were not for the first and second years. In conclusion, early summer months may be the crucial time to smoke the colonies with tobacco smoke in order to keep bee lice at low levels for the remaining seasons. 相似文献
95.
Robert A van den Berg Iven Van Mechelen Tom F Wilderjans Katrijn Van Deun Henk AL Kiers Age K Smilde 《BMC bioinformatics》2009,10(1):340
Background
In contemporary biology, complex biological processes are increasingly studied by collecting and analyzing measurements of the same entities that are collected with different analytical platforms. Such data comprise a number of data blocks that are coupled via a common mode. The goal of collecting this type of data is to discover biological mechanisms that underlie the behavior of the variables in the different data blocks. The simultaneous component analysis (SCA) family of data analysis methods is suited for this task. However, a SCA may be hampered by the data blocks being subjected to different amounts of measurement error, or noise. To unveil the true mechanisms underlying the data, it could be fruitful to take noise heterogeneity into consideration in the data analysis. Maximum likelihood based SCA (MxLSCA-P) was developed for this purpose. In a previous simulation study it outperformed normal SCA-P. This previous study, however, did not mimic in many respects typical functional genomics data sets, such as, data blocks coupled via the experimental mode, more variables than experimental units, and medium to high correlations between variables. Here, we present a new simulation study in which the usefulness of MxLSCA-P compared to ordinary SCA-P is evaluated within a typical functional genomics setting. Subsequently, the performance of the two methods is evaluated by analysis of a real life Escherichia coli metabolomics data set. 相似文献96.
97.
Phospholipase C gamma 1 (PLC gamma 1), an enzyme participating in phosphoinositide turnover, is one of the key elements in cell signaling. Here it is shown that treatment of A431 carcinoma cells with proteasome inhibitors Mg132 and lactacystin results in increasing the PLC gamma 1 intracellular level. Simultaneously, several additional bands with lower electrophoretic mobilities were detected on immunoblots, using anti-PLC gamma 1 antibodies. PLC gamma 1 ubiquitinilation was shown using immunoprecepitation. In control A 431 cells, PLC gamma 1 is ubiquitinilated, but the addition of EGF greatly induces the ubiquitinilation of the protein. Association of PLC gamma 1 with ubiquitin-ligase c-Cb1 was shown. Dynamics of ubiquitinilation under EGF treatment is in a close agreement with that of association of PLC gamma 1 and c-Cb1. It is concluded that PLC gamma 1 is ubiquitinilated and degraded by proteasomes. PLC gamma 1 ubiquitinilation is an EGF-dependent process. 相似文献
98.
Background
HTLV-I infection has been linked to lung pathology and HTLV-II has been associated with an increased incidence of pneumonia and acute bronchitis. However it is unknown whether HTLV-I or -II infection alters pulmonary function.Methods
We performed pulmonary function testing on HTLV-I, HTLV-II and HTLV seronegative subjects from the HTLV outcomes study (HOST), including vital capacity (VC), forced expiratory volume in one second (FEV1), and diffusing lung capacity for carbon monoxide (DLCO) corrected for hemoglobin and lung volume. Multivariable analysis adjusted for differences in age, gender, race/ethnicity, height and smoking history.Results
Mean (standard deviation) pulmonary function values among the 257 subjects were as follows: FVC = 3.74 (0.89) L, FEV1 = 2.93 (0.67) L, DLCOcorr = 23.82 (5.89) ml/min/mmHg, alveolar ventilation (VA) = 5.25 (1.20) L and DLCOcorr/VA = 4.54 (0.87) ml/min/mmHg/L. There were no differences in FVC, FEV1 and DLCOcorr/VA by HTLV status. For DLCOcorr, HTLV-I and HTLV-II subjects had slightly lower values than seronegatives, but neither difference was statistically significant after adjustment for confounding.Conclusions
There was no difference in measured pulmonary function and diffusing capacity in generally healthy HTLV-I and HTLV-II subjects compared to seronegatives. These results suggest that previously described HTLV-associated abnormalities in bronchoalveolar cells and fluid may not affect pulmonary function. 相似文献99.
Isospora dawadimiensis n. sp. is described from the jerboa, Jaculus jaculus, from Dawadimi, Saudi Arabia. Sporulated oocysts of I. dawadimiensis n. sp. were ovoidal or nearly subspherical 22–26.5 times 20.5–22 μm (24.4 times 21.4 μm). Oocyst wall had one layer. Micropyle, oocyst residuum, and polar granule were absent. Sporocysts were ellipsoid 12–16.5 times 9–10.5 μm (14.6 times 9.9 μm). Sporocyst residuum was present. The sporocysts lack a Stieda body. Sporozoites 8–11 times 2–3 μm (10 times 2.6 μm) were sausage-shaped, slightly curved, and tapered at one end. 相似文献
100.
Contrasting evolutionary rates in the duplicate chaperonin genes of Mycobacterium tuberculosis and M. leprae 总被引:3,自引:0,他引:3
A phylogenetic analysis of chaperonin (heat shock protein 60) sequences
from prokaryotes and eukaryotes indicated that a single gene duplication
event in the common ancestor of Mycobacterium tuberculosis, M. leprae, and
Streptomyces albus gave rise to the duplicate chaperonin genes found in
these species (designated HSP65 and GroEL in the mycobacterial species).
Comparison of rates of synonymous and nonsynonymous nucleotide substitution
in different gene regions suggested that the 5' end of the HSP65 gene was
homogenized by an ancient recombination event between M. tuberculosis and
M. leprae. In S. albus, the two duplicated chaperonin genes have evolved at
essentially the same rate. In both M. tuberculosis and M. leprae, however,
the GroEL gene has evolved considerably more rapidly at nonsynonymous
nucleotide sites than has the HSP65 gene. Because this difference is not
seen at synonymous sites, it must be due to a difference in selective
constraint on the proteins encoded by the two genes, rather than to a
difference in mutation rate. The difference between GroEL and HSP65 is
striking in regions containing epitopes recognized by T cells of the
vertebrate host; in certain cross-reactive epitopes conserved across all
organisms, nonsynonymous sites in GroEL have evolved twice as fast as those
in HSP65. It is suggested that these differences are correlated with
differences in the way in which the duplicate chaperonins of M.
tuberculosis and M. leprae interact with the host immune system.
相似文献