全文获取类型
收费全文 | 1290篇 |
免费 | 102篇 |
国内免费 | 2篇 |
出版年
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 21篇 |
2017年 | 25篇 |
2016年 | 35篇 |
2015年 | 53篇 |
2014年 | 58篇 |
2013年 | 74篇 |
2012年 | 94篇 |
2011年 | 88篇 |
2010年 | 49篇 |
2009年 | 56篇 |
2008年 | 97篇 |
2007年 | 83篇 |
2006年 | 73篇 |
2005年 | 80篇 |
2004年 | 76篇 |
2003年 | 71篇 |
2002年 | 72篇 |
2001年 | 14篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 15篇 |
1994年 | 17篇 |
1993年 | 9篇 |
1992年 | 17篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 14篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有1394条查询结果,搜索用时 362 毫秒
41.
Masayoshi Oyama Ken-ichi Nakashima Tetsuro Kamiya Manami Haba Tetsuro Ito Hiroko Murata Toshiyuki Tanaka Tetsuo Adachi Munekazu Iinuma Takeshi Kinoshita 《Phytochemistry letters》2013,6(2):215-218
Two novel flavonoids, named meliflavones A (1) and B (2), were isolated from the leaves of Melicope triphylla (Lam.) Merr., along with thirteen known compounds (3–15). Four of the polymethoxyflavonoids bearing a prenyloxy (3-methylbut-2-enyloxy) function (1, 3–5) induced the expression of extracellular-superoxide dismutase (EC-SOD) in a human leukemic U937 cell-based assay. 相似文献
42.
Tetsuro Ito Kouko Nishiya Masayoshi Oyama Toshiyuki Tanaka Jin Murata Dedy Darnaedi Munekazu Iinuma 《Phytochemistry letters》2013,6(4):667-670
Two O-glucosides of resveratrol dimers, ampelopsin F-11b-O-β-glucopyranosides with enantiomeric aglycones [cordifoloside A (1) and cordifoloside B (2)] and an enantiomer of the aglycone [(?)-ampelopsin F] were isolated from the leaves of Shorea cordifolia (Dipterocarpaceae). These structures were identified on the basis of spectroscopic evidence and their absolute configurations were elucidated using circular dichroism data. This is the first report on oligostilbenoids that demonstrates the co-occurrence of diastereomeric O-glucosides with enantiomeric aglycones in this family. 相似文献
43.
Homma Yuri Mita Kazuei Nakamura Yuki Namiki Toshiki Noda Hiroaki Shinoda Tetsuro Togawa Toru 《Applied Entomology and Zoology》2020,55(1):45-54
Applied Entomology and Zoology - Juvenile hormone (JH) has crucial roles in insect physiology, including development, reproduction, and polyphenism. JH is synthesized in the corpora allata (CA)... 相似文献
44.
45.
46.
47.
Tokushiro Takaso Yukitoshi Kimoto John N. Owens Masumi Kono Tetsuro Mimura 《Sexual plant reproduction》2013,26(1):17-23
In cycads, spermatozoids are released from pollen tubes and swim in fluid toward the archegonia. The source of this fluid was examined using Cycas revoluta Thunb. ovules placed in culture. Dissected female gametophytes just before fertilization produced copious fluid on their upper surface. The fluid first appeared around the archegonial chamber and then on the inside of the archegonial chamber. When this fluid was applied to dry turgid pollen tubes, they discharged spermatozoids 12 h later. The archegonial neck appeared as two semi-spherical swellings, whereas the four neck cells later became visible and they separated in a schizogenous manner. Many globose particles appear on the top of the archegonial neck cells when the fluid is present. The contents of pollen tubes, spermatozoids and surrounding liquid intermingle with the secreted fluid. The female gametophyte differs in ultrastructure during the stages before and after fluid secretion, the latter showing changes suggestive of fluid secretion from the female gametophyte. 相似文献
48.
Shigeyoshi Katohda Fumiko Suzuki Shigemi Katsuki Tetsuro Sato 《Bioscience, biotechnology, and biochemistry》2013,77(10):2029-2034
A kind of endo-β-1, 6-glucanase has been purified from the culture filtrate of Acinetobacter sp. grown in the medium containing baker’s yeast cells as a carbon source. A 100-fold purified preparation was obtained by DEAE-Sephadex A–50 column chromatography. The enzyme hydrolyzed pustulan giving a series of gentio-oligosaccharides and glucose. Gentiotriose and gentiotetraose were hydrolyzed by this enzyme yielding glucose and gentiobiose, and glucose, gentiobiose and gentiotriose, respectively. Gentiobiose was not hydrolyzed. Baker’s yeast glucans obtained from the isolated cell walls were also hydrolyzed by this enzyme giving a series of oligosaccharides and glucose. From the action patterns on these carbohydrates, we concluded the present enzyme being endo-β-1, 6-glucanase. 相似文献
49.
Although the electrolytically obtained DPNH was not completely oxidized by usual dehydrogenases or diaphorases, one of the authors noticed that its absorption band at 340 mμ disappeared completely when it was incubated with the extract of mung been seedlings. The reaction was found to be stimulated by the addition of methylene blue, and the product was identified as DPN. Thus, the reaction resembled that of diaphorase, although it was less specific to the configuration of DPNH. But unlike usual diaphorase, it required a cofactor, which was neither flavins nor metallic ion, but an unidentified acidic substance. General properties of the enzyme and the cofactor are reported in this article. 相似文献
50.