全文获取类型
收费全文 | 1468篇 |
免费 | 104篇 |
专业分类
1572篇 |
出版年
2022年 | 8篇 |
2021年 | 10篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 10篇 |
2016年 | 23篇 |
2015年 | 29篇 |
2014年 | 42篇 |
2013年 | 81篇 |
2012年 | 64篇 |
2011年 | 74篇 |
2010年 | 45篇 |
2009年 | 48篇 |
2008年 | 62篇 |
2007年 | 77篇 |
2006年 | 85篇 |
2005年 | 51篇 |
2004年 | 70篇 |
2003年 | 68篇 |
2002年 | 56篇 |
2001年 | 57篇 |
2000年 | 53篇 |
1999年 | 53篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 35篇 |
1991年 | 21篇 |
1990年 | 29篇 |
1989年 | 26篇 |
1988年 | 32篇 |
1987年 | 28篇 |
1986年 | 22篇 |
1985年 | 19篇 |
1984年 | 21篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 9篇 |
1974年 | 14篇 |
1973年 | 10篇 |
1972年 | 11篇 |
1971年 | 7篇 |
1970年 | 11篇 |
排序方式: 共有1572条查询结果,搜索用时 15 毫秒
21.
22.
23.
Masafumi Tomita Toshiko Okuyama Shoichi Sato Hideo Ishizu 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1993,621(2)
We applied micellar electrokinetic capillary chromatography to simultaneous separation and determination of nitrazepam and its major metabolites, 7-aminonitrazepam and 7-acetamidonitrazepam, in spiked urine. Prior to electrophoresis, the three compounds were successfully extracted from the spiked urine with commercial disposable solid-phase cartridges. The optimum running buffer for the separation was prepared by combining 85 parts of 60 mM sodium dodecyl sulphate—6 mM phosphate—borate, adjusted to pH 8.5, with 15 parts of methanol. The separation order, completed within 25 min, was 7-aminonitrazepam > 7-acetamidonitrazepam > nitrazepam, at an applied potential of 20 kV. We obtained reproducible electropherograms in successive repetitions, and few other peaks or interferences appeared in the electropherogram. The detection limits of the three compounds were 50–100 pg (0.1–0.2 μg/ml of analyte in spiked urine), and the recoveries were 78.9–100.8% for 1 μg/ml and 84.1–100.3% for 5 μg/ml. The application of this method to forensic or clinical samples is demonstrated. 相似文献
24.
Y. Tomita V. Bilim M. Takeda K. Takahashi 《Apoptosis : an international journal on programmed cell death》1996,1(3):209-212
The integration of Fas/Apo-1 (CD95) by Fas ligand or anti-Fas antibody induces apoptosis, and this system plays a pivotal role for the lysis of target cells by cytotoxic T lymphocytes. Fas-mediated apoptosis is also increased by a prior incubation of Fas-bearing cells with interferon(IFN)-. Interleukin-1- converting enzyme (ICE) and/or CPP32, or other members of ICE family act as direct cell death executors downstream of this mechanism, and a tetrapeptide inhibitor of these cysteine proteases blocks Fas-mediated apoptosis. In this study, we examined the effect of IFN- on Fas-mediated apoptosis in ACHN cells. IFN- augmented apoptosis in a dose dependent manner and reached a plateau at 400 U/ml when exposed for 48 h before the end of culture. The kinetics revealed a significant increase in apoptosis after 24 h. Exposing ACHN cells to IFN- increased pro-ICE expression accompanied with a decrease of pro-CPP32. These results suggest that direct enhancement of ICE expression and/or upregulation of conversion of pro-CPP32 to active form increases Fas-mediated apoptosis by IFN- in ACHN cells. 相似文献
25.
S. Takagi H. Sakata T. Yoshida K. Den T.K. Fujii H. Amemiya M. Tomita 《Prostaglandins & other lipid mediators》1978,15(5)
ONO-802 was used in the form of vaginal suppositories for the termination of early pregnancy in 63 healthy volunteers. Fifty-four (86%) of the 63 cases had complete abortions and remaining 9 (14%) had incomplete abortions.One (1.6%) of the 63 cases complained of nausea and vomiting, and 3 (4.8%) complained of headaches. No other side effects were observed.These results suggest that ONO-802 is acceptable in the form of vaginal suppositories for the termination of early pregnancy. 相似文献
26.
Toshimasa Ishida Ken-Ichi Tomita Masatoshi Inoue 《Archives of biochemistry and biophysics》1980,200(2):492-502
The crystal and molecular structures of the title complex has been determined by X-ray diffraction methods, as a model for tryptophan residues in protein-pyridine coenzyme interactions. The structure was solved by direct methods and was refined by standard methods (final R = 0.073). The light-green crystals consist of alternate layers of indole-3-acetic acid and 1-methyl-3-carbamoylpyridinium molecules piled up to the c-direction, and are stabilized by the crystal water participating in hydrogen bonds in the a- and b-directions. The parallel stackings and interplanar spacing distances between indole and pyridinium rings strongly suggest a II–II1 charge transfer from the indole ring to the lowest unoccupied orbital of the pyridinium ring in the ground state. Furthermore, this crystal structure provides evidence that quaternization of the N1 position enhances electron-acceptor properties of pyridine. On the other hand, the proton magnetic resonance spectra suggest that the stacking mode between both rings in solution is very similar to the one observed in the crystal structure. 相似文献
27.
Yasuko Mizuno Atsushi Ichikawa Kenkichi Tomita 《Prostaglandins & other lipid mediators》1983,26(5):785-795
The effect of 7-fluoro proscyclilin (PGI2-F), a chemically stable analogue of prostacyclin, on cAMP accumulation in and [3H]PGE binding to mastocytoma P-815 cells was compared with those of the Na salt and methyl ester of prostacyclin (PGI2Na or PGI2Me), which are rapidly inactivated in aqueous solution or metabolized in the tissue.PGIF was as effective as PGI2Me, and slightly less effective than PGI2Na in stimulating cAMP accumulation in mastocytoma cells and rabbit platelets. PGI2F was also more stable than PGI2Me or PGI2Na, and retained its original cAMP elevating activity even after incubation with or without cells for 4 h at 37°C. Cells which had been exposed to PGI2F and then washed free of unbound reagent continued to produced cAMP for more than 3 h. PGI2F was also as effective as PGE1 or PGE2 in displacing [3H]PGE2 bound to the cells. Non-competitive inhibition by PGI2F or PGI2Me of [3H]PGE2 binding to the cells, with apparent Kis of 1.29 μM and 1.13 μM, respectively, indicates the presence of different receptors for PGE2 and for PGI2F or PGI2Me in mastocytoma P-815 cells. 相似文献
28.
The effect of thrombospondin, a major glycoprotein in the platelet alpha-granule, on the erythrocyte aggregation rate was investigated. Venous blood was sampled from 8 healthy male volunteers and anticogulated with 1.1 mg/ml EDTA(K2). The erythrocyte aggregation rate of each blood sample was measured with a whole-blood erythrocyte aggregometer before and after incubation with murine monoclonal antibody against human platelet thrombospondin. After 15 min incubation, the erythrocyte aggregation rate exhibited a significant decrease to 0.055 +/- 0.022/s, representing 71.9 +/- 8.7% of the control value (0.075 +/- 0.028/s) (p less than 0.0005). The results obtained suggest that thrombospondin may participate in the control of erythrocyte aggregability in the circulating blood. 相似文献
29.
M Saito H Nojiri H Ogino A Yuo H Ogura M Itoh K Tomita T Ogawa Y Nagai S Kitagawa 《FEBS letters》1990,271(1-2):85-88
When HL-60 cells were cultivated with synthetic sialyl glycolipids, sialo-cholesterol and sialo-diglyceride, the cells were found to be differentiated into mature granulocytes on morphological and functional criteria. The differentiation of cells was accompanied by inhibition of cell proliferation. The differentiation-inducing activity of sialo-cholesterol was greater than that of sialo-diglyceride on a molar basis, and the alpha-anomer of each compound was more potent than the beta-anomer, suggesting that the stereospecific structure of the compounds is important for the differentiation-inducing activity. 相似文献
30.
Induction and stimulation of 92-kDa gelatinase/type IV collagenase production in osteosarcoma and fibrosarcoma cell lines by tumor necrosis factor alpha 总被引:10,自引:0,他引:10
Y Okada H Tsuchiya H Shimizu K Tomita I Nakanishi H Sato M Seiki K Yamashita T Hayakawa 《Biochemical and biophysical research communications》1990,171(2):610-617
Production of a 92-kDa gelatinase/type IV collagenase and tissue inhibitor of metalloproteinases (TIMP) was investigated with human sarcoma cell lines. Among the cytokines and growth factors examined, only human recombinant tumor necrosis factor alpha (TNF alpha) induced and stimulated the proteinase with concomitant increase in TIMP expression, but matrix metalloproteinase 2 (72-kDa gelatinase/type IV collagenase) expression was unchanged. These data suggest that gene expression of the two metalloproteinases is regulated in a different fashion and TNF alpha may be important to allow cancer cells to be more invasive and metastatic. 相似文献