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排序方式: 共有2713条查询结果,搜索用时 62 毫秒
211.
Ishizaki Takuma Komai Fuminori Masuda Kiyoshi 《Plant Cell, Tissue and Organ Culture》2001,67(3):251-255
A system for subculture of spinach (Spinacia oleracea L.) roots was established, and differences in regeneration; namely, embryogenic competence, among individuals of the `Nippon' cultivar were examined. Root tissues, excised from seedlings, were grown on medium without growth regulators and subcultured on the same medium and then on medium that contained 10 M naphthaleneacetic acid and 0.1 M gibberellic acid to induce callus formation. Calli were transferred to medium without growth regulators. All explants formed calli. However, the frequency of embryo formation varied among lines. Higher concentrations of gibberellic acid in the callus-induction medium had limited effects on somatic embryogenesis from poorly embryogenic lines. These results indicate that inherent factors are important for somatic embryogenesis in spinach and that the root subculture system is useful for identifying strongly regenerative genotypes among individuals of a single cultivar. 相似文献
212.
Phenotypic Characterization of Polysaccharidases Produced by Four Prevotella Type Strains 总被引:3,自引:0,他引:3
Matsui H Ogata K Tajima K Nakamura M Nagamine T Aminov RI Benno Y 《Current microbiology》2000,41(1):45-49
Four ruminal Prevotella type strains, P. ruminicola JCM8958T, P. bryantii B14T, P. albensis M384T, and P. brevis ATCC19188T, were characterized for polysaccharide-degrading activities with the reducing sugar release assay and zymogram analyses.
Carboxymethylcellulase, xylanase, and polygalacturonate (PG)-degrading enzyme activities were determined in cultures grown
on oat spelt xylan, xylose, arabinose, cellobiose, and glucose as sole growth substrates. P. ruminicola and P. albensis showed carboxymethylcellulase induction patterns. When xylan was supplied as a sole growth substrate, xylanase activities
produced by P. bryantii and P. albensis were at least 18- and 11-fold higher, respectively, than during growth on other carbohydrates, suggesting that the regulation
of the xylanases was highly specific to xylan. All strains constitutively produced PG-degrading enzymes. The corresponding
activity of P. bryantii was more than 40-fold higher than in other strains. Zymogram analyses routinely detected the presence of high-molecular-weight
(100–170 kDa) polysaccharide-degrading enzymes in ruminal Prevotella. Characteristics of the polysaccharide-degrading activities showed diversity of ruminal Prevotella species.
Received: 29 November 1999 / Accepted: 1 February 2000 相似文献
213.
214.
Ramsak A Peterka M Tajima K Martin JC Wood J Johnston ME Aminov RI Avgustin G 《FEMS microbiology ecology》2000,33(1):69-79
Molecular biology approaches were employed to examine the genetic diversity of bacteria from the Cytophaga/Flexibacter/Bacteroides (CFB) phylum in the rumen of cattle. By this means we were able to identify cultured strains that represent some of the larger CFB clusters previously identified only by PCR amplification and sequencing. Complete 16S rDNA sequences were obtained for 16 previously isolated rumen strains, including the type strains of Prevotella ruminicola, P. bryantii, P. brevis and P. albensis to represent a wide range of diversity. Phylogenetic analysis of cultured strains revealed the existence of three clusters of ruminal CFB: (i) a cluster of Prevotella strains, which have been found only in the rumen, including the two type strains, P. brevis GA33(T) and P. ruminicola 23(T); (ii) Prevotella spp. that cluster with prevotellas from other ecological niches such as the oral cavity and which include the type strains, P. bryantii B(1)4(T) and P. albensis M384(T); (iii) two Bacteroides spp. strains clustering with B. forsythus of oral origin. In order to establish whether the cultivated isolates cover the whole range of ruminal CFB genetic diversity, 16S rRNA gene sequences were amplified and cloned from DNA extracted from the same rumen samples (one cow in Slovenia, one in Scotland and three in Japan). Sequencing and phylogenetic analysis of 16S rRNA genes confirmed the existence of two superclusters of ruminal Prevotella, one exclusively ruminal and the other including non-ruminal species. In the case of ruminal Bacteroides spp., however, phylogenetic analysis revealed the existence of three new superclusters, one of which has as yet no cultivable counterpart. Interestingly, these Bacteroides clusters were represented almost exclusively by clone libraries from the Japanese cattle and only three sequences were from the European cattle. This study agrees with previous analyses in showing that rumen Prevotella/Bacteroides strains exhibit a remarkable degree of genetic diversity and suggests that different strain groupings may differ greatly in their recovery by cultural methods. The most important conclusion, however, is that cultured strains can be identified that represent some of the larger clusters previously identified only by PCR amplification and sequencing. 相似文献
215.
Balance of Activities of Alcohol Acetyltransferase and Esterase in Saccharomyces cerevisiae Is Important for Production of Isoamyl Acetate 总被引:2,自引:0,他引:2 下载免费PDF全文
Kiyoshi Fukuda Nagi Yamamoto Yoshifumi Kiyokawa Toshiyasu Yanagiuchi Yoshinori Wakai Katsuhiko Kitamoto Yoshiharu Inoue Akira Kimura 《Applied microbiology》1998,64(10):4076-4078
Isoamyl acetate is synthesized from isoamyl alcohol and acetyl coenzyme A by alcohol acetyltransferase (AATFase) in Saccharomyces cerevisiae and is hydrolyzed by esterases at the same time. We hypothesized that the balance of both enzyme activities was important for optimum production of isoamyl acetate in sake brewing. To test this hypothesis, we constructed yeast strains with different numbers of copies of the AATFase gene (ATF1) and the isoamyl acetate-hydrolyzing esterase gene (IAH1) and used these strains in small-scale sake brewing. Fermentation profiles as well as components of the resulting sake were largely alike; however, the amount of isoamyl acetate in the sake increased with an increasing ratio of AATFase/Iah1p esterase activity. Therefore, we conclude that the balance of these two enzyme activities is important for isoamyl acetate accumulation in sake mash. 相似文献
216.
Kobayashi K Suzuki SI Izawa Y Miwa K Yamanaka S 《The Journal of General and Applied Microbiology》1998,44(1):85-91
We screened various Bacillus species producing transglutaminase (TGase), measured as labeled putrescine incorporated into N,N-dimethylcasein. As a result, we detected TGase activity in sporulating cells of B. subtilis, B. cereus, B. alvei and B. aneurinolyticus, and found TGase activity related to sporulation. TGase activity of Bacillus subtilis was detected in lysozyme-treated sporulating cells during late sporulation, but not in cells without lysozyme treatment or the supernatant of the culture broth. TGase was found to be localized on spores. TGase was preliminarily purified by gel filtration chromatography for characterization. Its activity was eluted in the fractions indicating a molecular weight of approximately 23 kDa. TGase could cross-link and polymerize a certain protein. The enzyme was strongly suggested to form epsilon-(gamma-glutamyl)lysine bonds, which were detected in the spore coat proteins of B. subtilis. The activity was Ca(2+)-independent like the TGases derived from Streptoverticillium or some plants. It is suggested that TGase is expressed during sporulation and plays a role in the assembly of the spore coat proteins of the genus Bacillus. 相似文献
217.
Suzuki Kiyoshi; Baba Kei'ichi; Itoh Takao; Sone Yosbiaki 《Plant & cell physiology》1998,39(10):1003-1009
Localization of xyloglucan in cell walls regenerated from tobaccoprotoplasts (Nicotiana tabacum L.; cv. BY-2) is visualized byrapid-freezing and deep-etching (RFDE) electron microscopy coupledwith immunogold electron microscopy. Xyloglucan was alreadydeposited in the cell wall 3 h after culture initiation. Xyloglucanwas mainly localized along microfibrils with a lesser amountin intersections between two crossed microfibrils in 120-hour-oldcells. These data support the previous hypothesis of Keegstraet al. (1973) that propose an interconnection between xyloglucanand cellulose. (Received May 22, 1998; Accepted July 13, 1998) 相似文献
218.
Seiji Iwama Masaki Segawa Shinobu Fujii Kiyoshi Ikeda Shigeo Katsumura 《Bioorganic & medicinal chemistry letters》1998,8(24):781-3498
All stereoisomers of N-acyl-4,5-disubstituted oxazolidinone phospholipid analogs were synthesized by regio and stereoselective epoxide ring opening accompanied by introduction of an amino group. The (4R,5S)-derivative showed stronger inhibitory activity toward type II phospholipase A2 than the 4-substituted oxazolidinone phospholipid analog previously reported. 相似文献
219.
Taro Kawai Makoto Matsumoto Kiyoshi Takeda Hideki Sanjo Shizuo Akira 《Molecular and cellular biology》1998,18(3):1642-1651
220.
Ryunosuke Yoshino Nobuaki Yasuo Daniel Ken Inaoka Yohsuke Hagiwara Kazuki Ohno Masaya Orita Masayuki Inoue Tomoo Shiba Shigeharu Harada Teruki Honma Emmanuel Oluwadare Balogun Josmar Rodrigues da Rocha Carlos Alberto Montanari Kiyoshi Kita Masakazu Sekijima 《PloS one》2015,10(5)
BackgroundChagas disease, caused by the parasite Trypanosoma cruzi, is a neglected tropical disease that causes severe human health problems. To develop a new chemotherapeutic agent for the treatment of Chagas disease, we predicted a pharmacophore model for T. cruzi dihydroorotate dehydrogenase (TcDHODH) by fragment molecular orbital (FMO) calculation for orotate, oxonate, and 43 orotate derivatives.Conclusions/SignificanceFMO-based interaction energy analyses revealed a pharmacophore model for TcDHODH inhibitor. Hydrogen bond acceptor pharmacophores correspond to Lys43 and Lys214, hydrogen bond donor and acceptor pharmacophores correspond to Asn67 and Asn194, and the aromatic ring pharmacophore corresponds to FMN, which shows important characteristics of compounds that inhibit TcDHODH. In addition, the Lys214 residue is not conserved between TcDHODH and human DHODH. Our analysis suggests that these orotate derivatives should preferentially bind to TcDHODH, increasing their selectivity. Our results obtained by pharmacophore modeling provides insight into the structural requirements for the design of TcDHODH inhibitors and their development as new anti-Chagas drugs. 相似文献