全文获取类型
收费全文 | 931篇 |
免费 | 64篇 |
出版年
2022年 | 5篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 14篇 |
2017年 | 5篇 |
2016年 | 16篇 |
2015年 | 34篇 |
2014年 | 27篇 |
2013年 | 64篇 |
2012年 | 48篇 |
2011年 | 58篇 |
2010年 | 35篇 |
2009年 | 34篇 |
2008年 | 58篇 |
2007年 | 66篇 |
2006年 | 54篇 |
2005年 | 58篇 |
2004年 | 69篇 |
2003年 | 56篇 |
2002年 | 50篇 |
2001年 | 15篇 |
2000年 | 9篇 |
1999年 | 24篇 |
1998年 | 17篇 |
1997年 | 12篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 11篇 |
1988年 | 18篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 3篇 |
1968年 | 5篇 |
1967年 | 2篇 |
排序方式: 共有995条查询结果,搜索用时 46 毫秒
51.
Kawano M Igarashi K Yamato I Kakinuma Y 《The Journal of biological chemistry》2002,277(27):24405-24410
The 76-kDa NtpI subunit constitutes the membrane-embedded V(0) moiety of Enterococcus hirae vacuolar type Na+-ATPase with a 16-kDa NtpK hexamer containing Na+ binding sites. In this study, we investigated the role of an arginine residue, which is highly conserved among the corresponding subunits of bacterial vacuolar-type ATPases, at position 573 of NtpI. Substitution of Glu, Leu, or Gln for Arg-573 abolished sodium transport and sodium-stimulated ATP hydrolysis of the enzyme. The conservative replacement of Arg by Lys lowered both activities about one-fifth of those of the wild type enzyme. We have reported previously on ATP-dependent negative cooperativity for Na+ coupling of this enzyme (Murata, T., Kakinuma, Y., and Yamato, I. (2001) J. Biol. Chem. 276, 48337-48340). The negative cooperativity for the Na+ dependence of ATPase activity was weakened by the mutation R573K; the Hill coefficients for the wild type and mutant enzymes at a saturated ATP concentration were 0.22 +/- 0.03 and 0.40 +/- 0.05, respectively. The Hill coefficients of both enzymes at limited ATP concentrations approached 1. These results indicate that NtpI Arg-573 is indispensable for sodium translocation and for the cooperative features of E. hirae vacuolar-type ATPase. 相似文献
52.
Hitoshi Kumagai Yoshimi Oka Motoko Akita-TanakaKatsuya Inoue 《Inorganica chimica acta》2002,332(1):176-180
The hydrothermal synthesis, single crystal X-ray structure and magnetic properties of a two-dimensional (2-D) coordination polymer, [Ni4(C6(COO)6)(OH)2(H2O)6] (1), is described. Complex 1 consists of dimer motifs of pseudo octahedral NiO6 linked through μ3-OH to generate one-dimensional (1-D) chains which are further bridged by the mellitate ligands to form non interpenetrated undulating sheet structure. The sheets are further connected by hydrogen bonding interaction to yield a three-dimensional (3-D) structure. The temperature dependence of magnetic susceptibilities revealed the presence of antiferromagnetic interaction between nickel centers. 相似文献
53.
We here isolated an Enterococcus hirae mutant unable to grow well at pH 10. The influx rate calculated from steady-state 42K+/K+ exchange and the intracellular K+ concentration of the mutant were reduced to 53 and 55% of those of the wild-type, respectively. The activities of two high-affinity K+ uptake systems, KtrI and KtrII, were normal in the mutant, but the kinetics of net K+ uptake at pH 10 indicated that a low-affinity K+ uptake with a Km of about 20 mM (Kawano, M, Abuki, R, Igarashi, K, Kakinuma, Y. (2001) Arch. Microbiol. 175: 41-45), which were seen in the wild-type, was deficient in this mutant. 相似文献
54.
Cloned transchromosomic calves producing human immunoglobulin 总被引:16,自引:0,他引:16
55.
56.
The adhesive property to the intestinal mucin of Bifidobacterium lactis LKM512, B. longum, B. breve, B. bifidum, B. adolescentis, B. infantis, Bacteroides vulgatus, Bacteroides distasonis, Eubacterium aerofaciens,
Clostridium perfringens, Escherichia coli, and Lactobacillus acidophilus were examined. Adhesive rate of LKM512 to the mucin was significantly (p < 0.05, 0.01, or 0.001) stronger than the other strains from 2 to 100 time. Though the adhesive property of many strains was
almost same to the mucin of 20-year-old and 50-year-old generations, in case of 4-month-old was different. Adhesive inhibitory
effect of C. perfringens to the mucin by LKM512 was examined. Under the condition that LKM512 was 108/ml and that C. perfringens was 106/ml, adhesion of C. perfringens to the mucin was inhibited at 99.6%, when LKM512 adhered in advance. There was the strong inhibition of adhesion at 74.0%,
when C. perfringens adhered to mucin in advance. Thus, LKM512 can inhibit the adhesion of harmful bacteria to the intestinal mucin, the possibility
of using as a probiotic strain has to be verified. 相似文献
57.
Momose Y Honda T Inagaki M Shimizu K Irie K Nakanishi H Takai Y 《Biochemical and biophysical research communications》2002,292(1):45-49
We investigated whether and how rat liver thioredoxin reductase spares alpha-tocopherol in biomembranes. Purified hydroperoxides of beta-linoleoyl-gamma-palmitoylphosphatidylcholine were decreased 35% by treatment with thioredoxin reductase and 54% by thioredoxin reductase plus E. coli thioredoxin. Thioredoxin reductase also halved the amount of hydroperoxides that had been formed during photoperoxidation of liposomes composed of beta-linoleoyl-gamma-palmitoylphosphatidylcholine, and of emulsions of both cholesterol and cholesteryl linolenate. In erythrocyte ghosts, thioredoxin reductase spared alpha-tocopherol from oxidation by both soybean lipoxygenase and ferricyanide. Thioredoxin reductase also decreased F(2)-isoprostanes in ghosts oxidized by ferricyanide, suggesting that its ability to spare alpha-tocopherol relates to reduction of lipid hydroperoxides. 相似文献
58.
Summary. We investigated the behavior of migration of Amoeba proteus in an isotropic environment. We found that the trajectory in the migration of A. proteus is smooth in the observation time of 500-1000 s, but its migration every second (the cell velocity) on the trajectory randomly changes. Stochastic analysis of the cell velocity and the turn angle of the trajectory has shown that the histograms of the both variables well fit to Gaussian curves. Supposing a simple model equation for the cell motion, we have estimated the motive force of the migrating cell, which is of the order of piconewton. Furthermore, we have found that the cell velocity and the turn angle have a negative cross-correlation coefficient, which suggests that the amoeba explores better environment by changing frequently its migrating direction at a low speed and it moves rectilinearly to the best environment at a high speed. On the other hand, the model equation has simulated the negative correlation between the cell velocity and the turn angle. This indicates that the apparently rational behavior comes from intrinsic characteristics in the dynamical system where the motive force is not torquelike. 相似文献
59.
A subunit of the mammalian oligosaccharyltransferase, DAD1, interacts with Mcl-1, one of the bcl-2 protein family 总被引:4,自引:0,他引:4
DAD1 is a mammalian homologue of Saccharomyces cerevisiae Ost2p, a subunit of the oligosaccharyltransferase complex. Loss of its function induces apoptosis in hamster BHK21 cells. By means of a two-hybrid method involving DAD1 as bait, the C-terminal region of Mcl-1, one of the bcl-2 family, was isolated. Consistently, DAD1 binds well to Mcl-1 in COS cells when overexpressed. On deletion analysis, the C-terminal domain of Mcl-1 containing BH(2) (bcl-2 homologous domain) was found to be essential for the interaction with DAD1. On the other hand, the C-terminal half of DAD1 was concluded to be essential for the interaction with Mcl-1. Surprisingly, a DeltaC-DAD1 mutant lacking only 4 amino acid residues from the C-terminus did not complement the tsBN7 mutation, while it interacted well with Mcl-1. In contrast, DeltaN-DAD1 lacking 20 amino acid residues from the N-terminus still exhibited the ability to complement the tsBN7 mutation. Thus, the C-terminus of DAD1 was suggested to play an important role in N-linked glycosylation and to complement the tsBN7 mutation. Mcl-1 may be required for the inhibition of apoptotic cell death caused by a loss of DAD1. 相似文献
60.
Yoshimi M Sekiguchi T Hara N Nishimoto T 《Biochemical and biophysical research communications》2000,276(3):965-969
The tsBN7 cell line is one of the temperature-sensitive mutants for cell proliferation derived from hamster BHK21 cell line. It has a mutation in the DAD1 gene and enters apoptosis at the restrictive temperature of 39 degrees C. The defect of Dad1p causes a loss of N-linked glycosylation; therefore, it was thought that an inhibition of N-linked glycosylation induced apoptosis.However, tunicamycin, a potent inhibitor of N-linked glycosylation, had not caused apoptosis in wild-type BHK21 cells. In order to clarify this discrepancy, wild-type BHK21 cells treated with tunicamycin and tsBN7 cells incubated at 39.5 degrees C were examined by the annexin V staining and TUNEL methods. Both methods showed that tunicamycin induces apoptosis in wild-type BHK21 cells, similar to the defect of Dad1p. Thus, we concluded that loss of N-linked glycosylation causes apoptosis. 相似文献