全文获取类型
收费全文 | 6219篇 |
免费 | 362篇 |
国内免费 | 2篇 |
专业分类
6583篇 |
出版年
2023年 | 14篇 |
2022年 | 36篇 |
2021年 | 95篇 |
2020年 | 66篇 |
2019年 | 65篇 |
2018年 | 111篇 |
2017年 | 80篇 |
2016年 | 154篇 |
2015年 | 207篇 |
2014年 | 266篇 |
2013年 | 446篇 |
2012年 | 427篇 |
2011年 | 419篇 |
2010年 | 274篇 |
2009年 | 282篇 |
2008年 | 465篇 |
2007年 | 422篇 |
2006年 | 417篇 |
2005年 | 423篇 |
2004年 | 443篇 |
2003年 | 393篇 |
2002年 | 335篇 |
2001年 | 52篇 |
2000年 | 41篇 |
1999年 | 50篇 |
1998年 | 75篇 |
1997年 | 62篇 |
1996年 | 39篇 |
1995年 | 53篇 |
1994年 | 46篇 |
1993年 | 36篇 |
1992年 | 38篇 |
1991年 | 15篇 |
1990年 | 18篇 |
1989年 | 21篇 |
1988年 | 13篇 |
1987年 | 15篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 21篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 11篇 |
1976年 | 7篇 |
1974年 | 5篇 |
1969年 | 4篇 |
排序方式: 共有6583条查询结果,搜索用时 15 毫秒
121.
Satoshi Fukuzaki Naomichi Nishio Shiro Nagai 《Bioscience, biotechnology, and biochemistry》2013,77(9):2455-2460
Cobalt-free corrinoids (CFCs) were isolated from Methanosarcina barkeri Fusaro cells growing on a methanol minimum medium. The methanogen cells excreted a trace of CFCs (9.1 μg/I) into the culture medium when cobalt-deficient methanol medium was used. Several CFCs were separated by column chromatographies on ion exchangers and paper electrophoresis, where a major CFC showed a similar characteristic to that of nucleotide-free corrinoid, Factor B (cobinamide), suggesting to be hydrogenobinamide. By chemical insertion of Co2 +, Cu2 +, and Zn2+ into CFCs, the corresponding corrinoid and its metal analogues were observed. Bioassay using Escherichia coli 215 revealed that the major CFC (a yellow product obtained after alkaline treatment) and its copper and zinc analogues were inactive as cobalamin but were active as antimetabolites of cobalamin. However, the CFC greatly stimulated the cell growth of M. barkeri grown under cobalt-deficient conditions. 相似文献
122.
Carboxylic acids found in the cultured broth of Sporobolomyces odorus AHU 3246 which produces γ-lactones as principles of the aromatic flavor, were analyzed. The concentrate of methylated acids was steam-distilled and in the residue, succinic acid, nonanedioic acid (azelaic acid), undecanedioic acid and 2-hydroxy-3-phenylpropionic acid (β-phenyllactic acid) were identified as their methyl esters by GLC and spectroscopic methods. Phthalic acid and its mono-n-butyl ester were also found, but these compounds were thought to arise from di-n-butyl phthalate, one of impurities of deionized water. 相似文献
123.
Nobutaka Takahashi Akinori Suzuki Satoshi Miyamoto Rinpei Mori Saburo Tamura 《Bioscience, biotechnology, and biochemistry》2013,77(8):583-589
Molecular formula C25H37–39NO4 was assigned to Piericidin A. Through the examination of the ultraviolet, infrared and n.m.r. spectra and of chemical evidences, it was shown that Piericidin A contains one secondary alcohol, one acidic hydroxyl group, two methoxyl groups, tri- and tetra-substituted conjugated dienes and one polysubstituted heteroaromatic ring. 相似文献
124.
Jim Kawabata Yukiharu Fukushi Satoshi Tahara Junya Mizutani 《Bioscience, biotechnology, and biochemistry》2013,77(3):713-717
Three novel sesquiterpene alcohols, shizuka-acoradienol (2), shizukafuranol (3) and shizukol-idol (4), were isolated from Chloranthus japonicus Sieb. (Japanese name: Hitori-shizuka, Chloranthaceae). Their structures were elucidated on the basis of their physicochemical properties and some chemical reactions. Furanodienone (5), scopoletin (6a) and isoscopoletin (6b) were also isolated from this plant. 相似文献
125.
126.
Phyu Phyu Khine Zar Satoshi Yano Kozue Sakao Fumio Hashimoto Takayuki Nakano Makoto Fujii 《Bioscience, biotechnology, and biochemistry》2013,77(10):1731-1737
Fresh loquat leaves have been used as folk health herb in Asian countries for long time, although the evidence supporting their functions is still minimal. This study aimed to clarify the chemopreventive effect of loquat tea extract (LTE) by investigating the inhibition on proliferation, and underlying mechanisms in human promyelocytic leukemia cells (HL-60). LTE inhibited proliferation of HL-60 in a dose-dependent manner. Molecular data showed that the isolated fraction of LTE induced apoptosis of HL-60 as characterized by DNA fragmentation; activation of caspase-3, -8, and -9; and inactivation of poly(ADP)ribose polymerase. Moreover, LTE fraction increased the ratio of pro-apoptotic Bcl-2-associated X protein (Bax)/anti-apoptotic myeloid cell leukemia 1 (Mcl-1) that caused mitochondrial membrane potential loss and cytochrome c released to cytosol. Thus, our data indicate that LTE might induce apoptosis in HL-60 cells through a mitochondrial dysfunction pathway. These findings enhance our understanding for chemopreventive function of loquat tea. 相似文献
127.
Yoshihisa Tanaka Masanobu Kirita Yuko Abe Satoshi Miyata Motoyuki Tagashira Tomomasa Kanda 《Bioscience, biotechnology, and biochemistry》2013,77(7):1140-1146
Seven new O-methylated theaflavins (TFs) were synthesized by using O-methyltransferase from an edible mushroom. Using TFs and O-methylated TFs, metabolic stability in pooled human liver S9 fractions and inhibitory effect on H2O2-induced oxidative damage in human HepG2 cells were investigated. In O-methylation of theaflavin 3′-O-gallate (TF3′G), metabolic stability was potentiated by an increase in the number of introduced methyl groups. O-methylation of TF3,3′G did not affect metabolic stability, which was likely because of a remaining 3-O-galloyl group. The inhibitory effect on oxidative damage was assessed by measuring the viability of H2O2-damaged HepG2 cells treated with TFs and O-methylated TFs. TF3,3′G and O-methylated TFs increased cell viabilities significantly compared with DMSO, which was the compound vehicle (p?<?0.05), and improved to approximately 100%. Only TF3′G did not significantly increase cell viability. It was suggested that the inhibitory effect on H2O2-induced oxidative damage was potentiated by O-methylation or O-galloylation of TFs. 相似文献
128.
129.
Satoshi Ōmura Haruo Tanaka Juichi Awaya Yoshitsugu Narimatsu Yaeko onda Toju Hata 《Bioscience, biotechnology, and biochemistry》2013,77(5):899-906
In the course of our examination for the alkaloid productivities of Streptomyces strains, Streptomyces sp. NA–15 was found to produce a new alkaloid, pyrindicin, in the culture medium. The strain NA–15 was found to be a variant of Streptomyces griseoflavus and was designated as S. griseoflavus var. pyr indie us nov. var.After the culture conditions for pyrindicin production were studied, pyrindicin was obtained as its hydrochloride (mp 145°C, decomp.) from the cultured broth. The compound was shown to possess weak antimicrobial and several pharmacological activities. The LD50 of the hydrochloride (ip, in mice) was 87 mg/kg. 相似文献
130.
Keiji Yano Naoki Higashi Satoshi Nakamura Kei Arima 《Bioscience, biotechnology, and biochemistry》2013,77(9):1363-1365
The transglucosidation reaction of brewer’s yeast α-glucosidase was examined under the co-existence of l-sorbose and phenyl-α-glucoside. As the transglucosidation products, three kinds of new disaccharide were chromatographically isolated. It was presumed that these disaccharides consisting of d-glucose and l-sorbose were 1-O-α-d-glucopyranosyl-l-sorbose ([α]D+89.0), 3-O-α-d-glucopyranosyl-l-sorbose ([α]D+69.1) and 4-O-α-d-glucopyranosyl-l-sorbose ([α]D+81.0). The principal product formed in the enzyme reaction was 1-O-α-d-glucopyranosyl-l-sorbose. 相似文献