全文获取类型
收费全文 | 2458篇 |
免费 | 154篇 |
出版年
2023年 | 6篇 |
2022年 | 19篇 |
2021年 | 22篇 |
2020年 | 15篇 |
2019年 | 21篇 |
2018年 | 40篇 |
2017年 | 28篇 |
2016年 | 55篇 |
2015年 | 76篇 |
2014年 | 87篇 |
2013年 | 198篇 |
2012年 | 136篇 |
2011年 | 131篇 |
2010年 | 92篇 |
2009年 | 78篇 |
2008年 | 148篇 |
2007年 | 138篇 |
2006年 | 162篇 |
2005年 | 157篇 |
2004年 | 146篇 |
2003年 | 147篇 |
2002年 | 141篇 |
2001年 | 43篇 |
2000年 | 55篇 |
1999年 | 45篇 |
1998年 | 37篇 |
1997年 | 31篇 |
1996年 | 23篇 |
1995年 | 28篇 |
1994年 | 24篇 |
1993年 | 24篇 |
1992年 | 33篇 |
1991年 | 25篇 |
1990年 | 18篇 |
1989年 | 21篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 14篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1973年 | 8篇 |
排序方式: 共有2612条查询结果,搜索用时 109 毫秒
91.
Hiroyuki Nishimura Akio Asahi Kazuya Fujiwara Junya Mizutani Yataro Obata 《Bioscience, biotechnology, and biochemistry》2013,77(12):1831-1835
The effect of γ-irradiation on the flavor of Onions (Senshu Yellow) associated with sprout-inhibition has been investigated. The relative amounts of propionaldehyde, n-propyl mercaptan and di-n-propyl disulfide in onions stored for 0, 5, 10, 20 and 30 days, respectively, after irradiation were estimated by measurement of peak areas of gas chromatograms. It was observed that the lachrymatory character and the pungent flavor had been decreased by γ-irradiation (remarkably at 70 and 700 Krads). In this connection, the amounts of propionaldehyde and di-n-propyl disulfide were decreased with increasing radiation dose and storage period at room temperature (20 to 25°C) and at low temperature (4°C). Moreover, it was observed that the sweetness had been decreased by γ-irradiation, but the amount of n-propyl mercaptan was increased with radiation dose and storage period. Therefore it seems that there is no correlation between the sweetness of onion and the amount of n-propyl mercaptan. 相似文献
92.
Yoichi Ozawa Kenji Mori Masanao Matsui 《Bioscience, biotechnology, and biochemistry》2013,77(7):1383-1386
Thirty eight new compounds with juvenile hormone (JH) activity were synthesized and evaluated biologically on Bombyx mori L. Among them, the activities of 7,8-epoxy-4,8-dimethyl-1 -(p-ethylphenoxy)-3-undecene and 7,8-epoxy-4,8-dimethyl-l-(p-methylphenoxy)-3-undencene were proved to be more than two thousand times as high as that of the C18-Cecropia JH (mixed isomers). Structure-activity relationship of these compounds was discussed. 相似文献
93.
Masanao Matsui Kenji Mori Yoichi Ozawa 《Bioscience, biotechnology, and biochemistry》2013,77(2):193-195
A synthesis of oospolactone (3,4-dimethyl-8-hydroxyisocoumarin), a metabolite of Oospora astringenes, is described. 相似文献
94.
Yoshiaki Iwamuro Michiko Murata Koichiro Kanamaru Yoichi Mikami Takuro Kisaki 《Bioscience, biotechnology, and biochemistry》2013,77(2):525-526
The aroL gene, encoding shikimate kinase of Brevibacterium lactofermentum, a coryneform glutamic acid-producing bacterium, was cloned. Recombinant plasmids containing the aroL gene caused elevated levels of shikimate kinase synthesis in B. lactofermentum. It was found that in addition to the aroL gene, the aroB and aroE genes, encoding dehydroquinate synthase and shikimate dehydrogenase, respectively, also existed on these recombinant plasmids, in complementation tests with various Escherichia coli and B. lactofermentum aromatic amino acid auxotrophs. The aroL, aroB and aroE genes of B. lactofermentum are located closely on the cloned DNA fragment, in that order. It was shown that at least these three aro genes form a cluster on the chromosome of B. lactofermentum. 相似文献
95.
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
96.
Yoichi Ozawa Kenji Mori Masanao Matsui 《Bioscience, biotechnology, and biochemistry》2013,77(10):2373-2378
Sixteen new Cecropia juvenile hormone (JH) analogs with different alkyl substituents at C–7 and C–11 were synthesized as stereoisomeric mixtures. The epoxides with n-propyl or n-butyl and methyl groups at C-11 and methyl or ethyl group at C-7 showed high JH activity on Bombyx mori L. Structure-activity relationship of the JH analogs was discussed. 相似文献
97.
98.
Environmental perturbations influence telomere dynamics in long-lived birds in their natural habitat
Telomeres are regarded as markers of biological or cellular ageing because they shorten with the degree of stress exposure. Accordingly, telomere lengths should show different rates of change when animals are faced with different intensities of environmental challenges. However, a relationship between telomere length and the environment has not yet been tested within a natural setting. Here, we report longitudinal telomere dynamics in free-living, black-tailed gulls (Larus crassirostris) through the recapture of birds of a known age over 2–5 consecutive years. The rate of change in telomere lengths differed with respect to year but not sex or age. The years when gulls showed stable telomere lengths or increases in telomere lengths (from 2009 to 2010) and decreases in telomere lengths (from 2010 to 2011) were characterized by El Niño and the Great Japan Earthquake, respectively. Both events are suspected to have had long-lasting effects on food availability and/or weather conditions. Thus, our findings that telomere dynamics in long-lived birds are influenced by dramatic changes in environmental conditions highlight the importance of environmental fluctuations in affecting stress and lifespan. 相似文献
99.
100.
Kazuaki Yamanaka Yoichi Kakuta Shuji Miyagawa Shigeaki Nakazawa Taigo Kato Toyofumi Abe Ryoichi Imamura Masayoshi Okumi Akira Maeda Hiroomi Okuyama Masashi Mizuno Norio Nonomura 《PloS one》2016,11(2)