全文获取类型
收费全文 | 878785篇 |
免费 | 97136篇 |
国内免费 | 1117篇 |
出版年
2018年 | 8494篇 |
2017年 | 8035篇 |
2016年 | 11394篇 |
2015年 | 14983篇 |
2014年 | 17792篇 |
2013年 | 25128篇 |
2012年 | 28062篇 |
2011年 | 28746篇 |
2010年 | 19531篇 |
2009年 | 17977篇 |
2008年 | 25441篇 |
2007年 | 26331篇 |
2006年 | 24604篇 |
2005年 | 23713篇 |
2004年 | 23373篇 |
2003年 | 22150篇 |
2002年 | 21600篇 |
2001年 | 39985篇 |
2000年 | 39923篇 |
1999年 | 31568篇 |
1998年 | 10827篇 |
1997年 | 11355篇 |
1996年 | 10580篇 |
1995年 | 9831篇 |
1994年 | 9469篇 |
1993年 | 9504篇 |
1992年 | 25601篇 |
1991年 | 24837篇 |
1990年 | 24181篇 |
1989年 | 23532篇 |
1988年 | 21846篇 |
1987年 | 20638篇 |
1986年 | 19328篇 |
1985年 | 19047篇 |
1984年 | 15742篇 |
1983年 | 13504篇 |
1982年 | 10217篇 |
1981年 | 9232篇 |
1980年 | 8790篇 |
1979年 | 15032篇 |
1978年 | 11693篇 |
1977年 | 10717篇 |
1976年 | 10011篇 |
1975年 | 10970篇 |
1974年 | 12087篇 |
1973年 | 11755篇 |
1972年 | 10857篇 |
1971年 | 9923篇 |
1970年 | 8617篇 |
1969年 | 8313篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
951.
952.
Interactions between two catalytically distinct MCM subgroups are essential for coordinated ATP hydrolysis and DNA replication. 总被引:9,自引:0,他引:9
The six MCM (minichromosome maintenance) proteins are essential DNA replication factors that each contain a putative ATP binding motif and together form a heterohexameric complex. We show that these motifs are required for viability in vivo and coordinated ATP hydrolysis in vitro. Mutational analysis discriminates between two functionally distinct MCM protein subgroups: Mcm4p, 6p, and 7p contribute canonical ATP binding motifs essential for catalysis, whereas the related motifs in Mcm2p, 3p, and 5p serve a regulatory function. Reconstitution experiments indicate that specific functional interactions between these two subgroups are required for robust ATP hydrolysis. Our observations show parallels between the MCM complex and the F1-ATPase, and we discuss how ATP hydrolysis by the MCM complex might be coupled to DNA strand separation. 相似文献
953.
Brunner RM Srikanchai T Murani E Wimmers K Ponsuksili S 《Molecular biology reports》2012,39(1):97-107
Six genes that were known to exhibit expression levels that are correlated to drip loss BVES, SLC3A2, ZDHHC5, CS, COQ9, and
EGFR have been for candidate gene analysis. Based on in silico analysis SNPs were detected, confirmed by sequencing, and used for genotyping. The SNPs were genotyped in about 1,800 animals
from six pig populations including commercial herds of Pietrain (PI) and German Landrace (DL), different commercial herds
of Pietrain × (German Large White × German Landrace) (PIF1(a/b/c)), and one experimental F2-population Duroc × Pietrain (DUPI). Comparative and genetic mapping established the location of BVES on SSC1, of SLC3A2 and
ZDHHC5 on SSC2, of CS on SSC5, of COQ9 on SSC6 and of EGFR on SSC9, respectively, coinciding with QTL regions for carcass
and meat quality traits. BVES, SLC3A2, and CS revealed association at least with drip loss and with several other measures
of water holding capacity (WHC). Moreover, COQ9 and EGFR were associated with several meat quality traits such as meat color
and/or thawing loss. This study reveals statistic evidence in addition to the functional relationship of these genes to WHC
previously evidenced by expression analysis. This study reveals positional and genetic statistical evidence for a link of
genetic variation at these loci or close to them and promotes those six candidate genes as functional and/or positional candidate
genes for meat quality traits. 相似文献
954.
One novel approach for the biological delivery of peptide drugs is to incorporate the sequence of the peptide into the structure of a natural transport protein such as human serum transferrin (HST). However, a potential drawback is that the HST may increase the immunoreactivity of the peptide, in the same way that carrier proteins can be used to generate highly immunogenic peptide hapten conjugates. In this study we have generated a recombinant HST carrier protein that contains a peptide substrate of HIV-1 protease (VSQNYPIVL). The protein retained native HST function, and the peptide was surface exposed since it was immunoreactive in native dot blots, and was cleaved by HIV-1 protease. Immunisation of rabbits with the recombinant protein elicited only a very poor anti-peptide immune response. In contrast, strong anti-peptide immune responses were raised against both the peptide alone, and a chemical conjugate of the peptide with HST. These data demonstrate that it is possible to attenuate the immune response normally directed against an immunogenic peptide sequence by engineering into a surface exposed loop of HST. These findings may have an important impact on the future design of peptide delivery systems. 相似文献
955.
956.
S. P. Kharitonov D. E. Nowak A. I. Nowak N. A. Egorova S. A. Korkina D. V. Osipov O. V. Natal’skaya 《Biology Bulletin》2009,36(5):469-478
Red-breasted goose colonies have been studied near Medusa Bay (73°21′N, 80°32′E), on the northwestern Taimyr Peninsula, and
along the Agapa River (70°11′N, 86°15′E) down to its mouth (71°26′N, 89° 13′E), in the central Taimyr Peninsula. Red-breasted
geese nesting near peregrine falcons are protected by the falcons from arctic foxes; however, they are sometimes attacked
by the falcons themselves. In the colonies near peregrine falcon nests, the vast majority of goose nests were situated no
farther than 100 m from the falcon nest. When food is abundant, falcons protect a larger area around their nest. The distance
between the falcon nest and the surrounding goose nests is inversely related to the falcon’s activity. In years of higher
falcon activity, falcons prevent red-breasted geese from nesting as close to their nest as in years of lower falcon activity.
Additional stimuli are required for red-breasted geese to form colonies near rough-legged buzzard nests. The distance between
snowy owl nests and red-breasted goose nests was smaller when arctic foxes were abundant than when they were scarce. 相似文献
957.
958.
959.
Antonis E. Koromilas 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(3):644-649
Cells employ pro-survival and pro-adaptive pathways to cope with different forms of environmental stress. When stress is excessive, and the damage caused by it is unsustainable, cells engage pro-death pathways, which are in place to protect the host from the deleterious effects of harmed cells. Two important pathways that determine the balance between survival and death of stressed cells are the integrated stress response (ISR) and the mammalian target of rapamycin (mTOR), both of which converge at the level of mRNA translation. The two pathways have established avenues of communication to control their activity and determine the fate of stressed cells in a context-dependent manner. The functional interplay between the ISR and mTOR may have significant ramifications in the development and treatment of human diseases such as diabetes, neurodegeneration and cancer. 相似文献
960.
31P nuclear magnetic resonance (NMR) saturation-transfer (ST) techniques have been used to measure steady-state flows through phosphate-adenosine 5'-triphosphate (ATP) exchange reactions in glucose-grown derepressed yeast. Our results have revealed that the reactions catalyzed by glyceraldehyde-3-phosphate dehydrogenase/phosphoglycerate kinase (GAPDH/PGK) and by the mitochondrial ATPase contribute to the observed ST. Contributions from these reactions were evaluated by performing ST studies under various metabolic conditions in the presence and absence of either iodoacetate, a specific inhibitor of GAPDH, or the respiratory chain inhibitor antimycin A. Intracellular phosphate (Pi) longitudinal relaxation times were determined by performing inversion recovery experiments during steady-state ATP gamma saturation and were used in combination with ST data to determine Pi consumption rates. 13C NMR and O2 electrode measurements were also conducted to monitor changes in rates of glucose consumption and O2 consumption, respectively, under the various metabolic conditions examined. Our results suggest that GAPDH/PGK-catalyzed Pi-ATP exchange is responsible for antimycin-resistant saturation transfer observed in anaerobic and aerobic glucose-fed yeast. Kinetics through GAPDH/PGK were found to depend on metabolic conditions. The coupled system appears to operate in a unidirectional manner during anaerobic glucose metabolism and bidirectionally when the cells are respiring on exogenously supplied ethanol. Additionally, mitochondrial ATPase activity appears to be responsible for the transfer observed in iodoacetate-treated aerobic cells supplied with either glucose or ethanol, with synthesis of ATP occurring unidirectionally. 相似文献