全文获取类型
收费全文 | 3065篇 |
免费 | 197篇 |
国内免费 | 1篇 |
专业分类
3263篇 |
出版年
2022年 | 17篇 |
2021年 | 36篇 |
2020年 | 18篇 |
2019年 | 23篇 |
2018年 | 40篇 |
2017年 | 34篇 |
2016年 | 41篇 |
2015年 | 81篇 |
2014年 | 86篇 |
2013年 | 189篇 |
2012年 | 151篇 |
2011年 | 173篇 |
2010年 | 98篇 |
2009年 | 122篇 |
2008年 | 179篇 |
2007年 | 158篇 |
2006年 | 160篇 |
2005年 | 162篇 |
2004年 | 172篇 |
2003年 | 177篇 |
2002年 | 176篇 |
2001年 | 86篇 |
2000年 | 85篇 |
1999年 | 82篇 |
1998年 | 37篇 |
1997年 | 37篇 |
1996年 | 28篇 |
1995年 | 36篇 |
1994年 | 26篇 |
1993年 | 29篇 |
1992年 | 73篇 |
1991年 | 35篇 |
1990年 | 49篇 |
1989年 | 28篇 |
1988年 | 20篇 |
1987年 | 33篇 |
1986年 | 30篇 |
1985年 | 24篇 |
1984年 | 29篇 |
1983年 | 23篇 |
1982年 | 19篇 |
1981年 | 26篇 |
1980年 | 17篇 |
1979年 | 17篇 |
1978年 | 8篇 |
1976年 | 13篇 |
1974年 | 17篇 |
1973年 | 7篇 |
1972年 | 11篇 |
1970年 | 7篇 |
排序方式: 共有3263条查询结果,搜索用时 0 毫秒
91.
Shigeki Kishi 《Ecology and evolution》2022,12(3)
The characteristics of flower‒visitor networks, comprised of multiple species interacting with each other, predict ecological and evolutionary processes. Intraspecific and interspecific variations in interaction patterns should affect network structures. Because female and male visitors usually differ in flower‐visiting patterns due to mating strategy, visitor sex should affect nestedness, in which specialist species interact with a subset of species that interact with generalist species. I hypothesized that a network of male visitors and flowering plants would be more nested than a female network because males are less picky about which flowers they visit. To examine the effect of visitor sex on nestedness, I used museum specimens of insects and built 11 flower–visitor species networks, each composed of female and male subnetworks, and compared the strength of nestedness and related network metrics between the subnetworks. I found that male subnetworks were significantly more nested than female ones, and species networks were less nested than male or female subnetworks. The result may be attributable to the by‐chance selection of flowers by males. Because a nested structure is predicted to promote community stability in mutualistic flower–visitor networks, the greater nestedness of male subnetworks may suggest a positive effect of male visitors on pollination community stability. 相似文献
92.
Tomohiro Nishimura Shinya Sato Wittaya Tawong Hiroshi Sakanari Haruo Yamaguchi Masao Adachi 《Journal of phycology》2014,50(3):506-514
A new epiphytic dinoflagellate is described, G ambierdiscus scabrosus sp. nov., from tidal pools and rocky shores along the coastal areas of Japan. Cells are 63.2 ± 5.7 μm in depth, 58.2 ± 5.7 μm in width, and 37.3 ± 3.5 μm in length. The plate formula of G . scabrosus is Po, 4′, 0a, 6′′, 6c, ?s, 5′′′, 0p, and 2′′′′. Morphologically, G . scabrosus resembles G . belizeanus as follows: anterioposteriorly compressed cell shape, narrow 2′′′′ plate, and areolated surface. Despite this similarity, the cells of G . scabrosus can be distinguishable by the presence of the asymmetric shaped 3′′ plate and the rectangular shaped 2′ plate. 相似文献
93.
Hiraishi Katsuya; Suzuki Keiji; Hakomori Sen-itiroh; Adachi Masakazu 《Glycobiology》1993,3(4):381-390
Apoptosis (programmed cell death) is a basic physiological processwhich determines specific patterns of tissue size and shape,and balance of cell number, during morphogenesis, and seemsto play an integral role in oncogenic progression. Since dramaticchanges of cellular glycosylation pattern are well known tobe closely correlated with differentiation, development andoncogenesis, it is likely that similar specific changes areassociated with apoptosis. However, this possibility has notbeen systematically investigated. We therefore carried out histologicalstudies of many tumours and normal tissues for which a highincidence of apoptosis is believed to occur. Sections were stainedwith monoclonal antibodies (MoAbs) directed to carbohydrateantigens Ley and Lex, proliferating cellular nuclear antigen(PCNA) and Fas (previously claimed to be an apoptosis-inducingantigen). Antibody staining patterns were compared with morphologicalcell characteristics as revealed by haematoxylin/eosin staining,and DNA fragmentation patterns (a marker of apoptosis) as revealedby 3'-OH nick-end labelling technique. We found that expressionof Ley (defined by MoAb BM1) is closely correlated with theprocess of apoptosis, but not with cell proliferation or necrosis.Within Ley-positive areas of tissue sections, typical apoptoticmorphological changes and DNA fragmentation (as revealed bypositive nick-end labelling) were frequently observed in certainloci, although not all Ley-positive cells showed such signsof apoptosis. Ley-positive areas showed consistent negativestaining by MoAb directed to PCNA and negative or weak stainingby MoAb directed to Fas antigen, regardless of tissue source.No such trends were observed for Lex glycosylation. We concludethat Ley expression is a useful phenotypic marker predictiveof apoptosis, i.e. some (although not all) Ley-positive cellssubsequently become apoptotic. apoptosis expression glycosylation patterns Ley antigen 3'-OH nick-end labelling 相似文献
94.
Yuko Miyagoe-Suzuki Nami Masubuchi Kaori Miyamoto Michiko R. Wada Shigeki Yuasa Fumiaki Saito Kiichiro Matsumura Hironori Kanesaki Akira Kudo Hiroshi Manya Tamao Endo Shin’ichi Takeda 《Mechanisms of development》2009,126(3-4):107-116
Protein O-linked mannose β1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) is an enzyme that transfers N-acetylglucosamine to O-mannose of glycoproteins. Mutations of the POMGnT1 gene cause muscle–eye–brain (MEB) disease. To obtain a better understanding of the pathogenesis of MEB disease, we mutated the POMGnT1 gene in mice using a targeting technique. The mutant muscle showed aberrant glycosylation of α-DG, and α-DG from mutant muscle failed to bind laminin in a binding assay. POMGnT1?/? muscle showed minimal pathological changes with very low-serum creatine kinase levels, and had normally formed muscle basal lamina, but showed reduced muscle mass, reduced numbers of muscle fibers, and impaired muscle regeneration. Importantly, POMGnT1?/? satellite cells proliferated slowly, but efficiently differentiated into multinuclear myotubes in vitro. Transfer of a retrovirus vector-mediated POMGnT1 gene into POMGnT1?/? myoblasts completely restored the glycosylation of α-DG, but proliferation of the cells was not improved. Our results suggest that proper glycosylation of α-DG is important for maintenance of the proliferative activity of satellite cells in vivo. 相似文献
95.
96.
97.
98.
99.
100.
Minoru Ameyama Toshikazu Chiyonobu Osao Adachi 《Bioscience, biotechnology, and biochemistry》2013,77(8):1535-1536
The active site of α-glucosidase from Mucor javanicus IFO 4570 was investigated by kinetic studies. Competition between maltose and soluble starch, and linearity of Lineweaver-Burk plots for the mixed substrates were observed. The dependence of the apparent maximum velocities agreed with those predicted for a single active site mechanism. These results suggest that the enzyme hydrolyzes maltose and soluble starch at a single active site. 相似文献