全文获取类型
收费全文 | 3024篇 |
免费 | 38篇 |
国内免费 | 66篇 |
出版年
2023年 | 49篇 |
2022年 | 40篇 |
2021年 | 58篇 |
2020年 | 72篇 |
2019年 | 117篇 |
2018年 | 147篇 |
2017年 | 66篇 |
2016年 | 48篇 |
2015年 | 55篇 |
2014年 | 254篇 |
2013年 | 336篇 |
2012年 | 152篇 |
2011年 | 225篇 |
2010年 | 152篇 |
2009年 | 143篇 |
2008年 | 156篇 |
2007年 | 168篇 |
2006年 | 125篇 |
2005年 | 143篇 |
2004年 | 85篇 |
2003年 | 77篇 |
2002年 | 63篇 |
2001年 | 10篇 |
2000年 | 19篇 |
1999年 | 8篇 |
1998年 | 14篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 12篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1985年 | 18篇 |
1984年 | 39篇 |
1983年 | 29篇 |
1982年 | 37篇 |
1981年 | 21篇 |
1980年 | 23篇 |
1979年 | 24篇 |
1978年 | 17篇 |
1977年 | 11篇 |
1976年 | 19篇 |
1975年 | 7篇 |
1974年 | 14篇 |
1973年 | 9篇 |
1972年 | 2篇 |
排序方式: 共有3128条查询结果,搜索用时 15 毫秒
31.
By SDS-polyacrylamide gel electrophoresis, mitochondrial proteins having covalently-bound flavin were analyzed. Mitochondria were prepared from the liver of rat injected with radioactive riboflavin. Radioactivity was found to be associated with four protein components. Their subunit molecular weights were 91,000, 72,000, 60,000 and 44,000. The first two components exhibited yellowish fluorescence on a gel under ultraviolet illumination. The component of the highest molecular weight seems to be a new protein containing covalently-bound flavin. 相似文献
32.
We have studied the binding of β,γ-imido-adenosine-5′-triphosphate to glycerol-extracted insect flight and rabbit back muscle fibres. The binding was at relatively high affinity, of the same quantity as that of other nucleotides, and was inhibited by the presence of ATP. We concluded that imido-ATP bound, without hydrolysis, at the enzymic site of myosin. The mechanical effects of imido-ATP on the glycerol-extracted fibres were measured: concentrations sufficient to bind to myosin caused a small increase in the length of the rigor muscle for a given tension without alteration in the shape of the length-tension diagram. The magnitude of the length change paralleled the binding curve of imido-ATP to the fibre. We concluded that binding caused some change in myosin without its detachment from actin. Electron microscopy and X-ray diffraction studies of glycerol-extracted flight muscle fibres showed an increase in the angle of attachment of myosin to actin when imido-ATP was added. The results are discussed in relation to current concepts of force generation in active muscle. 相似文献
33.
Margaret F. Roberts 《Phytochemistry》1975,14(11):2393-2397
γ-Coniceine reductase, isolated from leaves and fruits of a number of Conium maculatum cultivars, was NADPH dependent. The hydride ion was transf 相似文献
34.
A new fraction has been isolated by chromatographic methods from the wax of the Bulgarian oil-bearing rose. According to its IR, NMR and MS it was characterized as an homologous series of γ-diols, from C17 to C33 with the major homologues those containing an odd number of carbon atoms. Nonacosane-5,8-diol is the major constituent. 相似文献
35.
蕨菜叶、茎中γ-氨基丁酸的提取分离及含量测定 总被引:1,自引:0,他引:1
用渗漉法对蕨菜叶、茎中的γ-氨基丁酸进行了提取,并用柱层析法对提取物进行了分离。采用双波长薄层扫描 法测定其含量,测得蕨菜叶、茎中γ-氨基丁酸的质量分数分别为0.319%、0.141%。采用该法测定γ-氨基丁酸操作简便、 快速,结果稳定。 相似文献
36.
目的观察血管内皮生长因子受体3(vascular endothelial growth factor receptor-3, VEGFR-3)蛋白在大鼠第15d胚胎和第21d胚胎皮肤淋巴管和血管内皮的表达水平,探讨VEGFR-3在胚胎淋巴管和血管发生发育中的生物功能.方法应用免疫组织化学技术(SABC法)对大鼠第15d和第21d胚胎共61例皮肤样本进行抗鼠VEGFR-3免疫组织化学染色,观察VEGFR-3在皮肤淋巴管和血管内皮细胞的表达情况.结果大鼠胚胎皮肤淋巴管和血管内皮细胞均阳性表达VEGFR-3蛋白,VEGFR-3蛋白在大鼠胚胎第15d、胚胎第21d皮肤淋巴管内皮细胞的阳性表达率分别是38.71%(12/31)和73.33%(22/30),第21d胚胎皮肤淋巴管VEGFR-3蛋白的表达水平明显高于第15d胚胎皮肤淋巴管VEGFR-3蛋白的表达水平(P<0.01).VEGFR-3蛋白在大鼠胚胎第15d、胚胎第21d皮肤血管内皮细胞的阳性表达率分别是48.39%(15/31)和46.67%(14/30),第15d和第 21d胚胎皮肤血管VEGFR-3蛋白的表达水平之间无明显差异(P>0.05).结论随着大鼠胚胎的发育,VEGFR-3蛋白在皮肤淋巴管的表达水平表现为明显上升的趋势,提示VEGFR-3在淋巴管发生发育中的作用逐渐增强. 相似文献
37.
38.
39.
Jeyoun Jang Minhui Cho Hae-Ri Lee Kiweon Cha Jeong-Hoon Chun Kee-Jong Hong Jungchan Park Gi-eun Rhie 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
The poly-γ-d-glutamic acid (PGA) capsule, a major virulence factor of Bacillus anthracis, protects bacilli from immune surveillance and allows its unimpeded growth in the host. Recently, the importance of the PGA in the pathogenesis of anthrax infection has been reported. The PGA capsule is associated with lethal toxin (LT) in the blood of experimentally infected animals and enhances the cytotoxicity of LT.Methods
To investigate the role of anti-PGA Abs on progression of anthrax infection, two mouse anti-PGA mAbs with Kd values of 0.8 μM and 2.6 μM respectively were produced and in silico three dimensional (3D) models of mAbs with their cognitive PGA antigen complex were analyzed.Results
Anti-PGA mAbs specifically bound encapsulated B. anthracis H9401 and showed opsonophagocytosis activity against the bacteria with complement. The enhancement effect of PGA on LT-mediated cytotoxicity was confirmed ex vivo using mouse bone marrow-derived macrophages and was effectively inhibited by anti-PGA mAb. Passive immunization of mAb completely protected mice from PGA-enhanced LT toxicity and partially rescued mice from anthrax spore challenges. 3D structure models of these mAbs and PGA complex support specific interactions between CDR and cognitive PGA. These results indicate that mouse mAb against PGA capsule prevents the progress of anthrax disease not only by eliminating the vegetative form of encapsulated B. anthracis but also by inhibiting the enhanced cytotoxic activity of LT by PGA through specific binding with PGA capsule antigen.General significance
Our results suggest a potential role for PGA antibodies in preventing and treating anthrax infection. 相似文献40.
Atanas G. Atanasov Jian N. Wang Shi P. Gu Jing Bu Matthias P. Kramer Lisa Baumgartner Nanang Fakhrudin Angela Ladurner Clemens Malainer Anna Vuorinen Stefan M. Noha Stefan Schwaiger Judith M. Rollinger Daniela Schuster Hermann Stuppner Verena M. Dirsch Elke H. Heiss 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013