全文获取类型
收费全文 | 1233篇 |
免费 | 87篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 12篇 |
2020年 | 14篇 |
2019年 | 14篇 |
2018年 | 15篇 |
2017年 | 25篇 |
2016年 | 28篇 |
2015年 | 44篇 |
2014年 | 46篇 |
2013年 | 87篇 |
2012年 | 89篇 |
2011年 | 69篇 |
2010年 | 47篇 |
2009年 | 46篇 |
2008年 | 99篇 |
2007年 | 96篇 |
2006年 | 73篇 |
2005年 | 74篇 |
2004年 | 61篇 |
2003年 | 61篇 |
2002年 | 50篇 |
2001年 | 31篇 |
2000年 | 32篇 |
1999年 | 19篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 8篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1960年 | 2篇 |
排序方式: 共有1320条查询结果,搜索用时 109 毫秒
41.
42.
Shinsaku Hayashida Kazuyoshi Ohta Perfecto Q. Flor Nobuya Nanri Ichiro Miyahara 《Bioscience, biotechnology, and biochemistry》2013,77(7):1947-1950
1-Pyrroline-5-carboxylate dehydrogenase was purified and crystallized from Bacillus sphaericus. The crystalline preparation gave a single band on polyacrylamide slab gel electrophoresis. The molecular weight of the enzyme was determined to be about 100,000 by gel filtration. The enzyme consists of two subunits which are identical in molecular weight (50,000), as judged on SDS slab gel electrophoresis. The enzyme shows an optimum pH of 6.5 to 7.0. Its activity was 8.1 times higher with NADP+ than with NAD +, and the enzyme was stabilized by NADP+. The apparent Km values for l-l-pyrroline-5-carboxylate, NADP+ and NAD+ are 4.2 × 10–5m (with NADP+), 9.5 × 10~6m and 2.5 × IO-3 m, respectively. The enzyme reaction is irreversible. A simple method for the determination of l-ornithine involving ornithine ¿-aminotransferase and 1- pyrroline-5-carboxylate dehydrogenase from B. sphaericus was developed. A linear relationship was found between the absorbance at 340 nm and the amount of l-ornithine (50 ~ 400 nmol), and between the fluorescence and the amount of l-ornithine (0.2 ~ 10 nmol). 相似文献
43.
Shinsaku Hayashida Kazuyoshi Ohta 《Bioscience, biotechnology, and biochemistry》2013,77(11):2561-2567
Chromatographically homogeneous phosphatidylcholine identified by thin-layer chromatography on silica gel G was isolated from mycelia of Aspergillus oryzae or egg yolk by a combination of alumina and silicic acid column chromatography. Although the 2-position in both Asp. oryzae- and egg yolk-phosphatidylcholine was occupied nearly exclusively by unsaturated fatty acids, significant proportions of unsaturated fatty acids were also found in the 1 -position of Asp. oryzae-phosphatidylcholine. In nitrogen gas-sparging anaerobic culture of Saccharomvces sake Kyokai No. 7, supplementing the basal synthetic medium with phosphatidylcholine enhanced the yeast growth and fermentative activity, whereas adding ergosteryl oleate enhanced alcohol-endurability. Supplementation with both phosphatidylcholine and ergosteryl oleate promoted the yeast growth, fermentative activity and alcohol-endurability of cells. 相似文献
44.
Effects of Aspergillus oryzae-proteolipid (PL) on the formation of high concentrations of alcohol, more than 20% as in sake brewing, have been studied. Electron microscopy revealed that there were no vacuoles but many lipid deposits in cytoplasm of the alcoholtolerant cells of Saccharomyces sake Kyokai No. 7, which were obtained by the anaerobic culture supplemented with PL. Sphaeroplasts from the alcohol-tolerant cells were stable in 20% alcohol, whereas those from the untolerant cells grown anaerobically in the PL-unsupplemented media were ruptured. The cell membrane became alcohol-endurable in the anaerobic cultures with PL. Synthetic phospholipid promoted yeast growth and the fermentative activity, whereas a small amount of sterol ester enhanced the alcohoi-endurability. The supplementation of both lipids anaerobically induced physiological properties characteristic of the alcohol-tolerant cells. 相似文献
45.
Kazunori Sasaki Tomoyuki Oki Yumi Kai Yoichi Nishiba 《Bioscience, biotechnology, and biochemistry》2013,77(8):1308-1314
The purpose of this study was to investigate the effect of repeated harvesting on the content of caffeic acid (CA) and seven species of caffeoylquinic acids (CQAs) in sweet potato leaves using a newly developed high-performance liquid chromatography method. Six cultivars and two breeding lines were used in this study. Leaves were collected at monthly intervals from 1st harvest (May) to 4th harvest (August) in 2011 and 2012. ANOVA analysis revealed that the contents of CQAs were significantly different among all cultivars and breeding lines, but no significant differences were found for CA. No annual variation was confirmed in CA and CQAs. Repeated harvest of sweet potato leaves affected the content of only 4-CQA and 5-CQA. Post-hoc comparisons using Tukey’s method indicated that the contents of 4-CQA and 5-CQA in sweet potato leaves harvested at first time were significantly higher compared to those at the other harvest times. 相似文献
46.
Shinsaku Hayashida Yoshio Watanabe 《Bioscience, biotechnology, and biochemistry》2013,77(8):2121-2123
Bacillus thuringiensis var. israelensis produces 130-kDa proteins which are toxic to mosquito larvae. The ISRH4 gene encoding 1,180 amino acids of the 130-kDa insecticidal protein was fused with lac Z′ on a plasmid, pUC19, and sequentially deleted from the C-terminus to construct a series of deletion mutants. All the deletion mutant genes directed the production of truncated ISRH4 proteins fused with the α-complementing fragment of β-galactosidase in Escherichia coli cells in the presence of isopropyl β-d-thiogalactopyranoside. Analysis of the mosquito larvicidal activity of deletion mutant proteins revealed that the N-terminal 29 amino acids and the C-terminal 485 amino acids could be removed without loss of the activity. 相似文献
47.
48.
49.
Toru Ishikawa Satoshi Abe Asami Hoshii Yumi Yamada Akihiko Iiduka Takeo Nemoto Keiko Takeda Toshiaki Yoshida 《PloS one》2016,11(1)
Background & Aims
The amount of drug-loaded lipiodol in an HCC tumor post-transarterial chemoembolization (TACE) correlates with the risk of local tumor recurrence. Lipiodol enhancement of a tumor on conventional CT, measured in Hounsfield units (HU), can predict tumor response. Here we investigate whether cone-beam CT (CBCT) can also be used to predict tumor response, providing the benefit of being able to optimize the patient’s treatment plan intra-procedurally.Methods
A total of 82 HCC nodules (82 patients), ≤5 cm in diameter, were treated with balloon-occluded TACE using miriplatin between December 2013 and November 2014. For each patient, both CBCT and conventional CT images were obtained post-TACE. The degree of correlation between CBCT and conventional CT was determined by comparing identical regions of interest for each imaging modality using pixel values.Results
The pixel values from conventional CT and CBCT were highly correlated, with a Pearson correlation coefficient of 0.912 (p<0.001). The location of the nodules within the liver did not affect the results; the correlation coefficient was 0.891 (p<0.001) for the left lobe and 0.926 (p<0.001) for the right lobe. The mean pixel value for conventional CT was 439 ± 279 HU, and the mean pixel value for CBCT was 416 ± 311 HU.Conclusions
CBCT may be used as a substitute for conventional CT to quantitatively evaluate the amount of drug-loaded lipiodol within an HCC nodule and, hence, the efficacy of TACE treatment. The major benefit of using CBCT is the ability to predict the likelihood of local recurrence intra-procedurally, enabling subsequent treatment optimization. 相似文献50.
Tadashi Moro Sachie Nakao Hideaki Sumiyoshi Takamasa Ishii Masaki Miyazawa Naoaki Ishii Tadayuki Sato Yumi Iida Yoshinori Okada Masayuki Tanaka Hideki Hayashi Satoshi Ueha Kouji Matsushima Yutaka Inagaki 《PloS one》2016,11(1)
Mitochondrial oxidative stress is considered as a key accelerator of fibrosis in various organs including the liver. However, the production of oxidative stress and progression of liver fibrosis may merely represent the independent consequences of hepatocellular injury caused by the primary disease. Because of a lack of appropriate experimental models to evaluate the sole effects of oxidative stress, it is virtually unknown whether this stress is causatively linked to the progression of liver fibrosis. Here, we examined the direct effects of mitochondrial reactive oxygen species (ROS) on the progression of high fat/calorie diet-induced steatohepatitis using Tet-mev-1 mice, in which a mutated succinate dehydrogenase transgene impairs the mitochondrial electron transport and generates an excess amount of ROS in response to doxycycline administration. Wild type and Tet-mev-1 mice that had been continuously given doxycycline-containing water were subsequently fed either normal chow or a cholesterol-free high-fat/high-sucrose diet for 4 months at approximately 1 or 2 years of age. Histopathological examinations indicated that neither the mitochondrial ROS induced in Tet-mev-1 mice nor the feeding of wild type animals with high-fat/high-sucrose diet alone caused significant liver fibrosis. Only when the Tet-mev-1 mice were fed a high-fat/high-sucrose diet, it induced lipid peroxidation in hepatocytes and enhanced hepatic CC chemokine expression. These events were accompanied by increased infiltration of CCR5-positive cells and activation of myofibroblasts, resulting in extensive liver fibrosis. Interestingly, this combinatorial effect of mitochondrial ROS and excess fat/calorie intake on liver fibrosis was observed only in 2-year-old Tet-mev-1 mice, not in the 1-year-old animals. Collectively, these results indicate that mitochondrial ROS in combination with excess fat/calorie intake accelerates liver fibrosis by enhancing CC chemokine production in aged animals. We have provided a good experimental model to explore how high fat/calorie intake increases the susceptibility to nonalcoholic steatohepatitis in aged individuals who have impaired mitochondrial adaptation. 相似文献