全文获取类型
收费全文 | 2599篇 |
免费 | 242篇 |
国内免费 | 480篇 |
出版年
2024年 | 11篇 |
2023年 | 36篇 |
2022年 | 66篇 |
2021年 | 66篇 |
2020年 | 65篇 |
2019年 | 75篇 |
2018年 | 58篇 |
2017年 | 53篇 |
2016年 | 56篇 |
2015年 | 86篇 |
2014年 | 95篇 |
2013年 | 155篇 |
2012年 | 152篇 |
2011年 | 157篇 |
2010年 | 119篇 |
2009年 | 150篇 |
2008年 | 172篇 |
2007年 | 152篇 |
2006年 | 156篇 |
2005年 | 140篇 |
2004年 | 130篇 |
2003年 | 119篇 |
2002年 | 119篇 |
2001年 | 119篇 |
2000年 | 97篇 |
1999年 | 82篇 |
1998年 | 35篇 |
1997年 | 22篇 |
1996年 | 21篇 |
1995年 | 24篇 |
1994年 | 19篇 |
1993年 | 25篇 |
1992年 | 42篇 |
1991年 | 52篇 |
1990年 | 45篇 |
1989年 | 49篇 |
1988年 | 40篇 |
1987年 | 34篇 |
1986年 | 20篇 |
1985年 | 32篇 |
1984年 | 23篇 |
1983年 | 16篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1974年 | 10篇 |
1969年 | 9篇 |
排序方式: 共有3321条查询结果,搜索用时 62 毫秒
141.
Shoji Ida Ikuo Kitamura Yuhei Morita 《Bioscience, biotechnology, and biochemistry》2013,77(5):715-723
Rice embryo peroxidase 556 was purified to the extent as indicated by the absorbance ratio, RZ greater than 4.0. The enzyme was found to be major basic component among isoenzymes of rice embryo. The preparation was homogeneous as examined by sedimentation analysis, and the sedimentation coefficient, s°20,w, was 3.76 S. The prosthetic group of the enzyme was identified as protohematin and its content was 1.36%. The minimum molecular weight was calculated to be 46,700. From the typical spectra of ligand-enzyme compounds, peroxidase 556 was found to react with carbon monoxide, cyanide, fluoride, and azide. However, at neutral pH, neither fluoride nor azide reacted with the enzyme. The high affinity of the enzyme to ammonia was one of the most remarkable characteristics of the enzyme. The hydrogen peroxide compounds I and II have been observed in the enzymic reaction, and therefore rice embryo peroxidase 556 is also concluded to follow the common reaction mechanism of plant peroxidases. Overall results show the close resemblance of rice embryo peroxidase 556 with wheat germ peroxidase 556 and hemoprotein 550. 相似文献
142.
Yuhei Morita Chiaki Yoshida Ikuo Kitamura Shoji Ida 《Bioscience, biotechnology, and biochemistry》2013,77(8):1191-1197
Japanese-radish root contained eighteen isoenzymes of peroxidase distinguishable on polyacrylamide gel electropherograms. The isoenzymes were found to be quite similar to those of horseradish peroxidase, although their quantities were different between two plants. The acidic components were the major isoenzyme in Japanese-radish peroxidase, while the neutral ones were the major one in horseradish. The chromatographic purification of the isoenzymes was performed on CM- and DEAE-Sephadex columns to characterize the components. The components in the preparations purified by the previously reported procedures of Morita et al. were also identified. 相似文献
143.
144.
145.
Keisuke Kitamura Kazuyoshi Okubo Kazuo Shibasaki 《Bioscience, biotechnology, and biochemistry》2013,77(5):1083-1085
Kinetics of the acyl transfer catalyzed by Xanthomonas α-amino acid ester hydrolase was studied. The enzyme hydrolyzed d-α-phenylglycine methyl ester (d-PG-OMe) to give equimolar amounts of d-α-phenylglycine and methanol. With d-PG-OMe as an acyl donor and 7-amino-3-deacetoxy-cephalosporanic acid (7-ADCA) as an acyl acceptor, the enzyme transferred the acyl group from d-PG-OMe to 7-ADCA in competition with water. The addition of amine nucleophiles (7-ADCA and 6-aminopenicillanic acid) decreased the molecular activity (ko) of the enzyme-catalyzed hydrolysis of d-PG-OMe, whereas it did not alter the Michaelis constant (KM), and plots of l/ko against the initial concentration of a nucleophile (no) gave a straight line. These results support the assumptions that the overall process for hydrolysis and acyl transfer proceeds through a common acyl-enzyme intermediate, that the acylation step of the enzyme is rate-limiting, and that the transfer competes with the hydrolysis of the acyl donor. 相似文献
146.
147.
148.
Izumi Uno Takashi Kozaka Daisuke Miwa Yoji Kitamura Mohammad Anwar-ul Azim Kazuma Ogawa Junichi Taki Seigo Kinuya Kazuhiro Shiba 《PloS one》2016,11(1)
Purpose
To develop a superior VAChT imaging probe for SPECT, radiolabeled (-)-OIDV and (+)-OIDV were isolated and investigated for differences in their binding affinity and selectivity to VAChT, as well as their in vivo activities.Procedures
Radioiodinated o-iodo-trans-decalinvesamicol ([125I]OIDV) has a high binding affinity for vesicular acetylcholine transporter (VAChT) both in vitro and in vivo. Racemic [125I]OIDV was separated into its two optical isomers (-)-[125I]OIDV and (+)-[125I]OIDV by HPLC. To investigate VAChT binding affinity (Ki) of two OIDV isomers, in vitro binding assays were performed. In vivo biodistribution study of each [125I]OIDV isomer in blood, brain regions and major organs of rats was performed at 2,30 and 60 min post-injection. In vivo blocking study were performed to reveal the binding selectivity of two [125I]OIDV isomers to VAChT in vivo. Ex vivo autoradiography were performed to reveal the regional brain distribution of two [125I]OIDV isomers and (-)-[123I]OIDV for SPECT at 60 min postinjection.Results
VAChT binding affinity (Ki) of (-)-[125I]OIDV and (+)-[125I]OIDV was 22.1 nM and 79.0 nM, respectively. At 2 min post-injection, accumulation of (-)-[125I]OIDV was the same as that of (+)-[125I]OIDV. However, (+)-[125I]OIDV clearance from the brain was faster than (-)-[125I]OIDV. At 30 min post-injection, accumulation of (-)-[125I]OIDV (0.62 ± 0.10%ID/g) was higher than (+)-[125I]OIDV (0.46 ± 0.07%ID/g) in the cortex. Inhibition of OIDV binding showed that (-)-[125I]OIDV was selectively accumulated in regions known to express VAChT in the rat brain, and ex vivo autoradiography further confirmed these results showing similar accumulation of (-)-[125I]OIDV in these regions. Furthermore, (-)-[123I]OIDV for SPECT showed the same regional brain distribution as (-)-[125I]OIDV.Conclusion
These results suggest that radioiodinated (-)-OIDV may be a potentially useful tool for studying presynaptic cholinergic neurons in the brain. 相似文献149.
Background & Objectives
Expertise of registered dietitians (RDs) is important for health guidance but has been poorly evaluated. We evaluated the kind of RD expertise that would improve their skills.Design, Setting, Participants, Measurements
This study was a post-hoc analysis of our randomized controlled trial, which compared the weight change between participants using the web-based self-disclosure health support and those using the email health support. Healthy men and women aged 35–64 years with a body mass index (BMI) of > = 24.5 kg/m2 were recruited for this study. We evaluated the relationship of RD expertise indicators including the duration of working as an RD, the experience of health counseling, and membership in the Japan Dietetic Association (JDA) with the weight loss of study participants. The primary endpoint was the change in body weight. Comparison of changes in body weight by the RD expertise indicators was evaluated using analysis of covariance.Results
A total of 175 participants were eligible for analyses. Changes in body weight were significantly greater when they were supported by the RDs in the routine counseling group than when supported by the RDs in the non-routine counseling group (-1.8 kg versus -0.4 kg, fully adjusted P = 0.0089). Duration of working as an RD and JDA membership did not significantly affect changes in body weight.Conclusions
Among some indices of RD experience, the experience of providing routine experience of health counseling was associated with weight loss. 相似文献150.
蒲氏钩蝠蛾Thitarodes pui(Zhang et al.)是冬虫夏草寄主昆虫之一,其雄成虫触角感受器在求偶交配过程中起主要作用。本研究应用电子扫描显微镜对蒲氏钩蝠蛾雄成虫触角上的化学感受器进行观察。结果发现,雄成虫触角上有7种感受器,即毛形感受器、刺形感受器、锥形感受器、腔锥形感受器、钟形感受器、Bhm氏鬃毛和鳞形感受器,其中以毛形感受器和鳞形感受器数目最多,腔锥感受器又分为长栓形和短栓形两种。综合本研究结果与已知蝠蛾的触角感受器,发现蝠蛾触角感受器在表面结构、感受器类型等方面与其它鳞翅目昆虫存在差异。 相似文献