全文获取类型
收费全文 | 1364篇 |
免费 | 95篇 |
国内免费 | 1篇 |
专业分类
1460篇 |
出版年
2022年 | 8篇 |
2021年 | 9篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 18篇 |
2016年 | 28篇 |
2015年 | 26篇 |
2014年 | 33篇 |
2013年 | 81篇 |
2012年 | 51篇 |
2011年 | 68篇 |
2010年 | 39篇 |
2009年 | 36篇 |
2008年 | 57篇 |
2007年 | 57篇 |
2006年 | 57篇 |
2005年 | 60篇 |
2004年 | 78篇 |
2003年 | 70篇 |
2002年 | 63篇 |
2001年 | 64篇 |
2000年 | 52篇 |
1999年 | 43篇 |
1998年 | 10篇 |
1997年 | 16篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 10篇 |
1993年 | 18篇 |
1992年 | 41篇 |
1991年 | 26篇 |
1990年 | 20篇 |
1989年 | 29篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 26篇 |
1985年 | 21篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1973年 | 7篇 |
1972年 | 9篇 |
1970年 | 9篇 |
排序方式: 共有1460条查询结果,搜索用时 15 毫秒
871.
Bin BH Fukada T Hosaka T Yamasaki S Ohashi W Hojyo S Miyai T Nishida K Yokoyama S Hirano T 《The Journal of biological chemistry》2011,286(46):40255-40265
The human SLC39A13 gene encodes ZIP13, a member of the LZT (LIV-1 subfamily of ZIP zinc transporters) family. The ZIP13 protein is important for connective tissue development, and its loss of function is causative for the spondylocheiro dysplastic form of Ehlers-Danlos syndrome. However, this protein has not been characterized in detail. Here we report the first detailed biochemical characterization of the human ZIP13 protein using its ectopic expressed and the purified recombinant protein. Protease accessibility, microscopic, and computational analyses demonstrated that ZIP13 contains eight putative transmembrane domains and a unique hydrophilic region and that it resides with both its N and C termini facing the luminal side on the Golgi. Analyses including cross-linking, immunoprecipitation, Blue Native-PAGE, and size-exclusion chromatography experiments indicated that the ZIP13 protein may form a homo-dimer. We also demonstrated that ZIP13 mediates zinc influx, as assessed by monitoring the expression of the metallothionein gene and by detecting the intracellular zinc level with a zinc indicator, FluoZin-3. Our data indicate that ZIP13 is a homo-dimerized zinc transporter that possesses some domains that are not found in other LZT family members. This is the first biochemical characterization of the physiologically important protein ZIP13 and the demonstration of homo-dimerization for a mammalian ZIP zinc transporter family member. This biochemical characterization of the human ZIP13 protein provides important information for further investigations of its structural characteristics and function. 相似文献
872.
873.
Fujinaga M Yamasaki T Kawamura K Kumata K Hatori A Yui J Yanamoto K Yoshida Y Ogawa M Nengaki N Maeda J Fukumura T Zhang MR 《Bioorganic & medicinal chemistry》2011,19(1):102-110
The purpose of this study was to synthesize 6-[1-(2-[18F]fluoro-3-pyridyl)-5-methyl-1H-1,2,3-triazol-4-yl]quinoline ([18F]FPTQ, [18F]7a) and to evaluate its potential as a positron emission tomography ligand for imaging metabotropic glutamate receptor type 1 (mGluR1) in the rat brain. Compound [18F]7a was synthesized by [18F]fluorination of 6-[1-(2-bromo-3-pyridyl)-5-methyl-1H-1,2,3-triazol-4-yl]quinoline (7b) with potassium [18F]fluoride. At the end of synthesis, 1280-1830 MBq (n = 8) of [18F]7a was obtained with >98% radiochemical purity and 118-237 GBq/??mol specific activity using 3300-4000 MBq of [18F]F−. In vitro autoradiography showed that [18F]7a had high specific binding with mGluR1 in the rat brain. Biodistribution study using a dissection method and small-animal PET showed that [18F]7a had high uptake in the rat brain. The uptake of radioactivity in the cerebellum was reduced by unlabeled 7a and mGluR1-selective ligand JNJ-16259685 (2), indicating that [18F]7a had in vivo specific binding with mGluR1. Because of a low amount of radiolabeled metabolite present in the brain, [18F]7a may have a limiting potential for the in vivo imaging of mGluR1 by PET. 相似文献
874.
Nemoto H Ishihara A Araki T Katagiri A Kamiya M Matsushita T Hattori H Mimura Y Tomoda Y Yamasaki M 《Bioorganic & medicinal chemistry letters》2011,21(16):4724-4727
Synthesis of a symmetrically branched diglycerol (BGL002, involving one iminodiacetic residue) as a G2 dendron, and the tetradecaglycerol (BGL014, involving one iminodiacetic residue) as a G4 dendron, is described. Several members of the BGL family of G2-G4 dendrons were assembled, with G2 bearing four hydroxyl groups at the terminus region, G3 bearing eight, and G4 bearing sixteen. It is noteworthy that triglycerol (BGL003, including no iminodiacetic residue), has a water-solubility ten times higher than BGL002, and the liposome surrounded by BGL014 has a duration period in blood vessel roughly two times longer than the liposome surrounded by dodecaglycerol (BGL012, including three iminodiacetic residues). 相似文献
875.
Yohei Bamba Tomoko Shofuda Daisuke Kanematsu Masahiro Nonaka Mami Yamasaki Hideyuki Okano Yonehiro Kanemura 《Biochemical and biophysical research communications》2014
Here we established a unique human glial cell line, GDC90, derived from a human glioma and demonstrated its utility as a glial scaffold for the polarization and differentiation of human induced pluripotent stem cell-derived neural progenitor cells (iPSC-NPCs). When co-cultured with GDC90 cells, iPSC-NPCs underwent rapid polarization and neurite extension along the radially spreading processes of the GDC90 cells, and showed migratory behavior. This method is potentially useful for detailed examination of neurites or for controlling neurites behavior for regenerative medicine. 相似文献
876.
Yo-ichi Ishida Masao Yamasaki Chizuko Yukizaki Kazuo Nishiyama Hirohito Tsubouchi Akihiko Okayama Hiroaki Kataoka 《Human cell》2014,27(2):68-77
Adult T-cell leukemia/lymphoma (ATL) is a fatal malignancy caused by infection with human T-lymphotropic virus type-1 and there is no accepted curative therapy for ATL. We searched for biological active substances for the prevention and treatment of ATL from several species of herbs. The ATL cell growth-inhibitory activity and apoptosis assay showed that carnosol, which is an ingredient contained in rosemary (Rosmarinus officinalis), induced apoptosis in ATL cells. Next, to investigate the apoptosis-inducing mechanism of carnosol, we applied proteomic analysis using fluorescent two-dimensional differential gel electrophoresis and mass spectrometry. The proteomic analysis showed that the expression of reductases, enzymes in glycolytic pathway, and enzymes in pentose phosphate pathway was increased in carnosol-treated cells, compared with untreated cells. These results suggested that carnosol affected the redox status in the cells. Further, the quantitative analysis of glutathione, which plays the central role for the maintenance of intracellular redox status, indicated that carnosol caused the decrease of glutathione in the cells. Further, N-acetyl-l-cystein, which is precursor of glutathione, canceled the efficiency of carnosol. From these results, it was suggested that the apoptosis-inducing activity of carnosol in ATL cells was caused by the depletion of glutathione. 相似文献
877.
Sucharit Basu Neogi Shinji Yamasaki Munirul Alam Rubén José Lara 《Wetlands Ecology and Management》2014,22(5):469-491
The increasing loads of anthropogenic pollutants, compounded with climate change events, are likely to induce environmental changes in many wetlands with impacts on the native microinvertebrates and pathogens causing increased occurrence of water-borne diseases, which affect millions of people each year. In wetlands bacterial pathogens are actively preyed on by many protozoa and filter-feeding organisms but this predation can be compensated by the nourishment and protection offered by certain microinvertebrates, acting as hosts, e.g., chitinous rotifers, copepods and cladocerans. The complex interactions of ecological, biological, and genetic components mediate disease-causing organisms to exploit microinvertebrate hosts to occupy diverse niches, obtain nutrition, and withstand physico-chemical stresses. The persistence of the human pathogens in wetlands is often enabled by their association with microinvertebrates and also depends on their quorum sensing mediated colonization, biofilm formation, switching into dormant stage, and horizontal transfer of adaptive genes. The symbiosis with microinvertebrates is facilitated by the pathogen’s immune evasion and fitness factors, e.g., Type-IV pili, capsular-polysaccharides, nutrient transportation, virulence and binding proteins, proteases, chitinases, and secretion systems. Spatio-temporal variation in the population of copepods and aquatic eggs/larvae of mosquitoes and midge flies, which act as vectors, can influence the outbreaks of cholera, diarrhea, malaria, dengue, filariasis and drucunculiasis. Changes in climatic factors (temperature, salinity, cyclones, rainfall, etc.) and anthropogenic pollutions (sewage, fertilizer and insecticide) may modify the abundance and biodiversity of microinvertebrates, and thus possibly exacerbate the persistence and dispersal of water-borne pathogens. Thus there is a need to adopt ecohydrological and eco-friendly interventions for managing wetlands while conserving them. 相似文献
878.
Nitric oxide (NO) is involved in versatile functions in plant growth and development as a signaling molecule. To date, plants have been reported to produce NO following exposure to nitrite (N O 2 ? ) the amino acid L-arginine, hydroxylamine, or polyamines. Here we demonstrate azide-dependent NO production in plants. The water fern Azolla pinnata emitted NO into air upon exposure to sodium azide (NaN3). The NO production was dependent on azide concentration and was strongly inhibited by potassium cyanide (KCN). Incubation of A. pinnata with the catalase inhibitor 3-aminotriazole (3-AT) abolished the azide-dependent NO production. Although nitrite-dependent NO production was inhibited by sodium azide, azide-dependent NO production was not affected by nitrite. These results indicate that A. pinnata enzymatically produces NO using azide as a substrate. We suggest that plants are also capable of producing NO from azide by the action of catalase as previously reported in animals. 相似文献
879.
Two new species belonging to the Echinoderes coulli group are described with their external morphologies and sequences of nuclear 18S rRNA and 28S rRNA genes, and mitochondrial COI gene. The first species, Echinoderes komatsui
sp. n., is characterized by absence of acicular spines, and presence of lateroventral tubules on segments 5 and 8, laterodorsal tubules on segment 10, inverted triangle or wide oval shaped large sieve plates, lateral terminal accessory spines in female, and short tips of ventral pectinate fringe on segment 10. The second species, Echinoderes hwiizaa
sp. n., is characterized by absence of acicular spines, and presence of lateroventral tubules on segments 5 and 7–9, midlateral tubules on segment 8, laterodorsal tubules on segment 10, large narrow oval shaped sieve plates on segment 9, and thick, short and blunt lateral terminal spines about 10–15% of trunk length. The diagnostic characters and key to species of E. coulli group are provided as well. 相似文献
880.
Shingo Noguchi Kazuhiro Yatera Ke-Yong Wang Keishi Oda Kentarou Akata Kei Yamasaki Toshinori Kawanami Hiroshi Ishimoto Yumiko Toyohira Hiroaki Shimokawa Nobuyuki Yanagihara Masato Tsutsui Hiroshi Mukae 《Respiratory research》2014,15(1):92