全文获取类型
收费全文 | 2044篇 |
免费 | 110篇 |
国内免费 | 3篇 |
专业分类
2157篇 |
出版年
2023年 | 3篇 |
2022年 | 13篇 |
2021年 | 19篇 |
2020年 | 13篇 |
2019年 | 19篇 |
2018年 | 24篇 |
2017年 | 30篇 |
2016年 | 45篇 |
2015年 | 58篇 |
2014年 | 72篇 |
2013年 | 169篇 |
2012年 | 111篇 |
2011年 | 144篇 |
2010年 | 83篇 |
2009年 | 114篇 |
2008年 | 149篇 |
2007年 | 128篇 |
2006年 | 124篇 |
2005年 | 134篇 |
2004年 | 114篇 |
2003年 | 128篇 |
2002年 | 138篇 |
2001年 | 32篇 |
2000年 | 24篇 |
1999年 | 17篇 |
1998年 | 24篇 |
1997年 | 20篇 |
1996年 | 26篇 |
1995年 | 19篇 |
1994年 | 18篇 |
1993年 | 10篇 |
1992年 | 14篇 |
1991年 | 7篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 15篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1980年 | 5篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1974年 | 8篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有2157条查询结果,搜索用时 15 毫秒
11.
Shinichi Watanabe Masayoshi Osumi Takamitsu Ohnishi Eiko Ichikawa Hisashi Takahashi 《Histochemistry and cell biology》1995,103(6):425-433
In order to investigate the re-epithelialization process during wound healing, the hair on the back of guinea pigs was shaved and then excisional wounds were made through the entire thickness of the skin. Histological changes were observed and changes in the expression of different cytokeratin polypeptides were examined using an immunohistochemical technique. Immunohisto chemical study revealed that the proliferating and migrating keratinocytes expressed the same cytokeratins as the basal cells of normal epidermis. In addition, the entire epidermis of fairly remote areas from the edges of the wound where no thickening was observed showed a temporarily abnormal staining pattern. The suprabasal cells in the regenerating epidermis temporarily expressed cytokeratins not only specific for suprabasal cells but also specific for basal cells. The cytokeratins expressed in normal basal keratinocytes were also present in the thickened granular layers. These data indicate that the expression of cytokeratins in the epidermal keratinocytes (even in fairly remote areas from the wound edges) changes during wound healing, that the origin of the migrating keratinocytes from the remaining epidermis seems to be the basal cells in the epidermis, and that the appearance of keratohyalin granules is not related to changes in cytokeratin expression. 相似文献
12.
Hisashi Yamasaki Chiaki Katagiri Norio Yoshizaki 《Development, growth & differentiation》1990,32(1):65-72
The embryonic hatching process in the toad, Bufo japonicus , consists of two phases: rupture of the outer jelly strings at stage 20 (neural tube) and an escape from the inner jelly layers and fertilization coat (FC) of individual embryos at stage 23 (tailbud). SDS-PAGE analyses of FCs revealed that, of the eight major protein bands, two components with 58 K and 62 K in molecular weight gradually decreased from stage 18–19 on and totally disappeared at stage 22. When the FCs were treated with a hatching medium prepared by culturing denuded prehatching embryos, both 58 K and 62 K components of the FCs were solubilized, and in the solubilized materials 18 K and 31 K components appeared. Electron microscopy showed that a meshwork of filament bundles present in the FCs before stage 17 became dissociated at stage 19–20, and completely disappeared at stage 23, just before the hatching of embryos. Hatching gland cells (HGCs), an epidermal cell with numerous secretory granules, were first identified at stage 19, and underwent active secretion of the granules during stage 19–23. These results indicate that the hydrolytic degradation of 58K and 62 K components in FCs effected by the hatching enzyme constitutes the basic mechanism of embryonic hatching during both the first and second phases. 相似文献
13.
14.
Yuko Watanabe Eri Furukawa Hideki Tatsukawa Hisashi Hashimoto Yasuhiro Kamei Yoshihito Taniguchi 《Bioscience, biotechnology, and biochemistry》2018,82(7):1165-1168
Transglutaminase (TG) is an essential enzyme to catalyze cross-linking reactions of epidermal proteins. Recently, we biochemically characterized human skin TG orthologues for medaka (Oryzias latipes), a model fish. By genome editing, gene-modified fishes for the two orthologues were obtained, both of which lack the ordinal enzymes. These fish appeared to exhibit higher susceptibility to osmolality at the period of larvae. 相似文献
15.
Hisashi Mizutani Hideaki Sugawara Ashley M. Buckle Takeshi Sangawa Ken-ichi Miyazono Jun Ohtsuka Koji Nagata Tomoki Shojima Shohei Nosaki Yuqun Xu Delong Wang Xiao Hu Masaru Tanokura Kei Yura 《BMC structural biology》2017,17(1):4
Background
More than 7000 papers related to “protein refolding” have been published to date, with approximately 300 reports each year during the last decade. Whilst some of these papers provide experimental protocols for protein refolding, a survey in the structural life science communities showed a necessity for a comprehensive database for refolding techniques. We therefore have developed a new resource – “REFOLDdb” that collects refolding techniques into a single, searchable repository to help researchers develop refolding protocols for proteins of interest.Results
We based our resource on the existing REFOLD database, which has not been updated since 2009. We redesigned the data format to be more concise, allowing consistent representations among data entries compared with the original REFOLD database. The remodeled data architecture enhances the search efficiency and improves the sustainability of the database. After an exhaustive literature search we added experimental refolding protocols from reports published 2009 to early 2017. In addition to this new data, we fully converted and integrated existing REFOLD data into our new resource. REFOLDdb contains 1877 entries as of March 17th, 2017, and is freely available at http://p4d-info.nig.ac.jp/refolddb/.Conclusion
REFOLDdb is a unique database for the life sciences research community, providing annotated information for designing new refolding protocols and customizing existing methodologies. We envisage that this resource will find wide utility across broad disciplines that rely on the production of pure, active, recombinant proteins. Furthermore, the database also provides a useful overview of the recent trends and statistics in refolding technology development.16.
Ueno Y Shinki T Nagai Y Murayama H Fujii K Suda T 《Journal of cellular biochemistry》2003,90(2):267-277
It is known that pharmacological or toxic doses of vitamin D induce bone resorption both in vivo and in vitro, whereas physiological doses of the vitamin have a protective effect on bone in vivo. To investigate the discrepancies of the dose-dependent effect of vitamin D on bone resorption, we examined the in vivo effect of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] on the expression of the receptor activator of nuclear factor-kappaB (NF-kappaB) ligand (RANKL) and osteoprotegerin (OPG) mRNAs in bone of thyroparathyroidectomized (TPTX) rats infused with or without parathyroid hormone (PTH). Continuous infusion of 50 ng/h of PTH greatly increased the expression of RANKL mRNA in bone of TPTX rats. Expression of OPG mRNA was not altered by PTH infusion. When graded doses of 1,25(OH)(2)D(3) was daily administered orally for 14 days to normocalcemic TPTX rats constantly infused with PTH, 0.01 and 0.1 microg/kg of 1,25(OH)(2)D(3) inhibited the PTH-induced RANKL mRNA expression, but 0.5 microg/kg of the vitamin did not inhibit it. Regulator of G protein signaling-2 (RGS-2) gene expression was suppressed by 1,25(OH)(2)D(3) dose-dependently, but PTH/PTHrP receptor mRNA expression was not altered. Bone morphometric analyses revealed that 1,25(OH)(2)D(3) suppressed PTH-induced osteoclast number in vivo. These results suggest that pharmacological or toxic doses of 1,25(OH)(2)D(3) stimulate bone resorption by inducing RANKL, but a certain range of physiological doses of the vitamin inhibit PTH-induced bone resorption, the latter mechanism appeared to be mediated, at least in part, by the suppression of the PTH/PTHrP receptor-mediated signaling. 相似文献
17.
Atsushi Ishihara Fumio Matsuda Hisashi Miyagawa Kyo Wakasa 《Metabolomics : Official journal of the Metabolomic Society》2007,3(3):319-334
Advances in molecular breeding technologies have enabled manipulation of the concentrations of specific plant components by
modifying the genes that play a key role in their production. This has provided new opportunities to enhance the nutritional
quality of major crops. However, given that metabolic pathways form a highly integrated network, any alteration in a given
biosynthetic pathway is most likely to effect secondary and unpredicted changes in the metabolite profile of other pathways.
Metabolomics technologies can contribute to the efficient detection of such unexpected effects caused by genetic modification.
This has relevance not only from the perspective of safety evaluations of newly developed crops, but to basic science focused
on uncovering hitherto unknown regulatory mechanisms associated with the biosynthesis and catabolism of primary and secondary
metabolites in plants. In this review, recent advances in plant metabolic engineering for the overproduction of tryptophan
(Trp), one of the essential amino acids, are described. In particular, the efficacy of a transgene OASA1D that encodes a mutant anthranilate synthase (AS) α subunit of rice in specifically elevating levels of Trp without marked
secondary effects on the metabolite profile of rice is demonstrated. Related topics, such as regulation of Trp biosynthesis,
possible interactions between the biosyntheses of Trp and other aromatic amino acids, and translocation of Trp in are discussed
based on findings derived from metabolomic analyses of Trp-overproducing transgenic plants. 相似文献
18.
19.
20.
Hinako Shirakata Hisashi Nishiwaki 《Bioscience, biotechnology, and biochemistry》2020,84(10):1986-1996
ABSTRACT All eight stereoisomers of conidendrin were synthesized from (1 R,2 S,3 S)-1-(4-benzyloxy-3-methoxyphenyl)-3-(4-benzyloxy-3-methoxybenzyl)-2- hydroxymethyl-1,4-butanediol ((+)-4) and its enantiomer with high optical purity. The configurations at 4-positions of the conidendrin stereoisomers were constructed by intramolecular Friedel-Crafts reaction of protected 4. After conversion to tetrahydronaphthalene intermediate 7a, the 2- and 3-position of tetrahydronaphthalene structure 7a were converted to 3a- and 9a-position of (+)-α-conidendrin (3a), respectively. By the epimerization process of 2- or 3-position of 7a, the other diastereomers were obtained. All enantiomers were also synthesized from (?)-4. 相似文献