全文获取类型
收费全文 | 1552篇 |
免费 | 117篇 |
专业分类
1669篇 |
出版年
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 10篇 |
2015年 | 30篇 |
2014年 | 27篇 |
2013年 | 75篇 |
2012年 | 65篇 |
2011年 | 50篇 |
2010年 | 40篇 |
2009年 | 39篇 |
2008年 | 78篇 |
2007年 | 88篇 |
2006年 | 81篇 |
2005年 | 77篇 |
2004年 | 90篇 |
2003年 | 66篇 |
2002年 | 52篇 |
2001年 | 65篇 |
2000年 | 70篇 |
1999年 | 57篇 |
1998年 | 21篇 |
1997年 | 28篇 |
1996年 | 19篇 |
1995年 | 26篇 |
1994年 | 26篇 |
1993年 | 22篇 |
1992年 | 51篇 |
1991年 | 50篇 |
1990年 | 53篇 |
1989年 | 20篇 |
1988年 | 43篇 |
1987年 | 25篇 |
1986年 | 22篇 |
1985年 | 19篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 13篇 |
1977年 | 4篇 |
1976年 | 10篇 |
1975年 | 8篇 |
1974年 | 13篇 |
1973年 | 5篇 |
1969年 | 4篇 |
1968年 | 6篇 |
排序方式: 共有1669条查询结果,搜索用时 10 毫秒
101.
102.
Our recent studies indicated that Rhodamine fibrosarcoma (RdF) tissue of rats accumulated large amounts of albumin and transferrin and that these proteins were essential for growth of RdF cells in primary cultures in serum-free medium. Therefore, the localizations of albumin and transferrin accumulated in RdF tissue were examined by immunohistochemical stainings. Both anti-rat albumin IgG and anti-rat transferrin IgG stained the cell surface of the tumor cells strongly, but the intracellular area only weakly. 相似文献
103.
Saiki C Ikeda M Nishikawa T Tanimoto T Yoshida S Matsumoto S 《Canadian journal of physiology and pharmacology》2001,79(12):1036-1043
To examine the process of spontaneous autoresuscitation and the recovery of the hypoxic ventilatory response (HVR) after prolonged anoxia, we monitored respiratory frequency (f, by body plethysmography) and heart rate (HR, by ECG) in intact newborn rats (n = 12, day 2-4) before, during, and after 100% N2 exposure. The rat before anoxia showed signs of HVR: f changes at acute hypoxia (10% O2) and hyperoxia (100% O2). During anoxia, the spontaneous respiratory movement "gasping" appeared for 21 min (mean). At O2 restoration (with 100% O2), gasping stopped and no respiratory flow was detected for 1 min. One rat failed to autoresuscitate and had heart arrhythmia during the transient apnea, but 11 rats recovered respiration after the HR acceleration. Despite the successful autoresuscitation, the rats did not show HVR at 10 min into the recovery period and the recovery of HVR required more than 30 min. The results indicate that O2 inhalation is useful to trigger autoresuscitation even when the rat has already been in a state of profound hypoxic depression, but the rat becomes transiently insensitive to HVR after autoresuscitation. We estimate that reform of the respiratory control system in newborn rats is not yet firmly established to track HVR early in the recovery phase after prolonged anoxia. 相似文献
104.
Molecular cloning of delta-4, a new mouse and human Notch ligand 总被引:14,自引:0,他引:14
Yoneya T Tahara T Nagao K Yamada Y Yamamoto T Osawa M Miyatani S Nishikawa M 《Journal of biochemistry》2001,129(1):27-34
105.
Arai S Ogawa K Yamachika S Nishihara T Nishikawa J 《Biochimica et biophysica acta》2001,1518(1-2):7-18
The factors SRC-1, TIF2 and ACTR were identified as interacting with nuclear receptors in a highly ligand-dependent manner. Because the molecular mass of each of these factors is approximately 160 kDa, they are collectively termed p160 coactivators. So far, p160 coactivators have been cloned from human, mouse and Xenopus. We report here the cloning of the chicken homologues of p160 coactivator members. As in human and mouse, chicken has three p160 coactivators. Each gene encodes an approximately 160 kDa protein which exhibits 70-80% amino acid sequence identity to human and mouse p160 coactivators. Chicken p160 coactivators also have the property of interacting with several liganded nuclear receptors. Moreover, we describe an imperfect LXXLL sequence, termed NR box 4, which is located downstream of NR box 3 and conserved between evolutionarily diverse species. The loss of NR box 4 results in a decrease of interaction with the nuclear receptor, which indicates that NR box 4 is required for efficient interaction. 相似文献
106.
Involvement of serum mannan binding proteins and mannose receptors in uptake of mannosylated liposomes by macrophages 总被引:7,自引:0,他引:7
Opanasopit P Higuchi Y Kawakami S Yamashita F Nishikawa M Hashida M 《Biochimica et biophysica acta》2001,1511(1):134-145
The roles of serum mannan binding protein (MBP) and the mannose receptor in the cellular uptake of mannosylated liposomes (Man-liposomes) by macrophages were studied. Man-liposomes were prepared by incorporating cholesten-5-yloxy-N-(4-((1-imino-2-beta-D-thiomannosylethyl)amino)butyl)formamide (Man-C4-Chol) into small unilamellar long circulating liposomes consisting of cholesterol (Chol) and distearoyl phosphatidylcholine (DSPC). In the in vitro cellular uptake study with cultured mouse peritoneal macrophages, [(3)H]Man-liposomes were taken up to a great extent, whereas no significant uptake was observed for [(3)H]cholesterol and DSPC liposomes without Man-C4-Chol (Bare-liposomes). The uptake of [(3)H]Man-liposomes was dose- and temperature-dependent and inhibited by an excess of mannosylated bovine serum albumin, suggesting their specific uptake via membrane mannose receptor-mediated endocytosis. Furthermore, it was demonstrated that (111)In-MBP binds strongly to Man-liposomes based on the recognition of Man-C4-Chol and markedly enhanced their uptake by macrophages. These results are supported by confocal laser microscopic images. In addition, in vivo hepatic uptake of (111)In-MBP was enhanced by Man-liposomes. On the other hand, the uptake of Man-liposomes was significantly reduced by preincubation with serum and further with MBP-depleted serum suggesting inhibitory effects of serum proteins such as albumin on mannose receptor-mediated endocytosis. The involvement of serum-type MBP and membrane mannose receptors in the uptake of Man-liposomes is thus suggested. 相似文献
107.
108.
109.
Nishikawa Y Wang Z Kerns J Wilcox CS Carr BI 《The Journal of biological chemistry》1999,274(49):34803-34810
We recently found that a thioether analog of K vitamin (Cpd 5) inhibited the activity of protein-tyrosine phosphatases (PTPases) and induced protein-tyrosine phosphorylation in a human hepatoma cell line (Hep3B). We have now examined the structural requirements for induction of protein-tyrosine phosphorylation and PTPase inhibition by several K vitamin analogs. Thioether analogs with sulfhydryl arylation capacity, especially those with a hydroxy (Cpd 5) or a methoxy group at the end of the side chain, induced protein-tyrosine phosphorylation, but non-arylating analogs, such as those with an all-carbon or O-ether side chain, did not. Among the receptor-tyrosine kinases, epidermal growth factor receptors were tyrosine-phosphorylated by treatment with thioether analogs, whereas insulin and hepatocyte growth factor receptors were not. An increase in tyrosine-phosphorylated ERK2 mitogen-activated protein kinase was also observed. The activity of purified T cell PTPase was inhibited only by the thioether analogs, but not by non-arylating analogs. Furthermore, the epidermal growth factor receptor dephosphorylation activity of Hep3B cell lysates was inhibited by Cpd 5 treatment. A similar induction of protein-tyrosine phosphorylation by Cpd 5 was seen in other human hepatoma cell lines together with growth inhibition. However, one cell line (HepG2), which was relatively resistant to growth inhibition by Cpd 5, did not increase its phosphorylation levels upon Cpd 5 treatment. These results suggest that cell growth inhibition by thioether analogs is closely associated with inhibition of PTPases by sulfhydryl arylation and with tyrosine phosphorylation of selected proteins. 相似文献
110.
The effect of molecular mass and surface density of galactose residues on hepatic uptake and subsequent biliary excretion of galactosylated proteins was investigated in rats. Several proteins with different molecular weights (15-70 kDa) and different numbers of galactose units were synthesized and radiolabeled with 111In. Galactosylated proteins were administered i.v. to anaesthetized rats and samples of plasma and bile were collected for 3 h. Liver was harvested at the end of the experiments and the radioactivity of all samples was measured. Galactosylated proteins accumulated primarily in the liver and 2-10% of the administered dose appeared in the bile, mainly in undegraded form. The hepatic uptake clearance (Cl liver) and biliary excretion rate constant (kbile) of galactosylated proteins were calculated. No direct effect of molecular weight was observed, however, on increasing the galactose density, Cl liver increased from about 4 to 400 ml/h whereas kbile gradually decreased from about 0.057 to 0.007 (h-1). In conclusion, both hepatic uptake and biliary excretion of galactosylated proteins were found to be affected by the extent of galactosylation. 相似文献