全文获取类型
收费全文 | 48483篇 |
免费 | 3737篇 |
国内免费 | 3544篇 |
出版年
2024年 | 84篇 |
2023年 | 530篇 |
2022年 | 1130篇 |
2021年 | 2243篇 |
2020年 | 1559篇 |
2019年 | 1966篇 |
2018年 | 2090篇 |
2017年 | 1700篇 |
2016年 | 2212篇 |
2015年 | 2564篇 |
2014年 | 3296篇 |
2013年 | 3541篇 |
2012年 | 4041篇 |
2011年 | 3755篇 |
2010年 | 2658篇 |
2009年 | 2342篇 |
2008年 | 2667篇 |
2007年 | 2399篇 |
2006年 | 2085篇 |
2005年 | 1720篇 |
2004年 | 1616篇 |
2003年 | 1510篇 |
2002年 | 1231篇 |
2001年 | 1004篇 |
2000年 | 840篇 |
1999年 | 618篇 |
1998年 | 383篇 |
1997年 | 321篇 |
1996年 | 309篇 |
1995年 | 321篇 |
1994年 | 291篇 |
1993年 | 225篇 |
1992年 | 291篇 |
1991年 | 260篇 |
1990年 | 208篇 |
1989年 | 192篇 |
1988年 | 129篇 |
1987年 | 175篇 |
1986年 | 145篇 |
1985年 | 128篇 |
1984年 | 101篇 |
1983年 | 96篇 |
1982年 | 82篇 |
1981年 | 78篇 |
1980年 | 52篇 |
1979年 | 62篇 |
1978年 | 66篇 |
1976年 | 51篇 |
1973年 | 63篇 |
1972年 | 52篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Journal of Ichthyology - The feeding of burbot Lota lota was studied in the modern conditions of the Kuibyshev Reservoir. With the decrease in the abundance of ruff Gymnocephalus cernuus in the... 相似文献
992.
Jun Sun Wei Wu Xiaofeng Tang Feifei Zhang Cheng Ju Renfeng Liu Yiping Liang Bo Yu Bin Lv Yuhong Guo Duo Zeng Xuchang Tao Min Wang Zhiping Zhang Changhua Zhang Xiao-Bin Lv 《Bioscience reports》2021,41(4)
Background: WT161, as a selective HDAC6 inhibitor, has been shown to play anti-tumor effects on several kinds of cancers. The aim of the present study is to explore the roles of WT161 in osteosarcoma and its underlying mechanisms.Methods: The anti-proliferative effect of WT161 on osteosarcoma cells was examined using MTT assay and colony formation assay. Cell apoptosis was analyzed using flow cytometer. The synergistic effect was evaluated by isobologram analysis using CompuSyn software. The osteosarcoma xenograft models were established to evaluate the anti-proliferative effect of WT161 in vivo.Results: WT161 suppressed the cell growth and induced apoptosis of osteosarcoma cells in a dose- and time-dependent manner. Mechanistically, we found that WT161 treatment obviously increased the protein level of PTEN and decreased the phosphorylation level of protein kinase-B (AKT). More importantly, WT161 showed synergistic inhibition with 5-FU on osteosarcoma cells in vitro and in vivo.Conclusions: These results indicate that WT161 inhibits the growth of osteosarcoma through PTEN and has a synergistic efficiency with 5-FU. 相似文献
993.
994.
Li‐Hsuan Ho Yung‐I Lee Shu‐Ying Hsieh I‐Shiuan Lin Yun‐Chien Wu Han‐Yu Ko Patrick A. Klemens H. Ekkehard Neuhaus Yi‐Min Chen Tzu‐Pi Huang Chih‐Hsin Yeh Woei‐Jiun Guo 《Plant, cell & environment》2021,44(1):20-33
Gastrodia elata, a fully mycoheterotrophic orchid without photosynthetic ability, only grows symbiotically with the fungus Armillaria. The mechanism of carbon distribution in this mycoheterotrophy is unknown. We detected high sucrose concentrations in all stages of Gastrodia tubers, suggesting sucrose may be the major sugar transported between fungus and orchid. Thick symplasm‐isolated wall interfaces in colonized and adjacent large cells implied involvement of sucrose importers. Two sucrose transporter (SUT)‐like genes, GeSUT4 and GeSUT3, were identified that were highly expressed in young Armillaria‐colonized tubers. Yeast complementation and isotope tracer experiments confirmed that GeSUT4 functioned as a high‐affinity sucrose‐specific proton‐dependent importer. Plasma‐membrane/tonoplast localization of GeSUT4‐GFP fusions and high RNA expression of GeSUT4 in symbiotic and large cells indicated that GeSUT4 likely functions in active sucrose transport for intercellular allocation and intracellular homeostasis. Transgenic Arabidopsis overexpressing GeSUT4 had larger leaves but were sensitive to excess sucrose and roots were colonized with fewer mutualistic Bacillus, supporting the role of GeSUT4 in regulating sugar allocation. This is not only the first documented carbon import system in a mycoheterotrophic interaction but also highlights the evolutionary importance of sucrose transporters for regulation of carbon flow in all types of plant‐microbe interactions. 相似文献
995.
996.
997.
998.
999.
1000.
【背景】金针菇菌种在继代培养的过程中会出现菌种退化的现象,影响着金针菇的产量与质量。【目的】为研究金针菇退化菌种菌丝的生理生化特征,筛选金针菇退化菌株。【方法】以金针菇原始菌株(H)和退化菌株(T)为研究对象,测定不同碳源培养基上菌丝的生理生化特征及超氧化物歧化酶(SuperoxideDismutase,SOD)、过氧化物酶(Peroxidase,POD)和过氧化氢酶(Catalase,CAT)的活性,并测定菌丝在栽培瓶中的漆酶(Laccase,Lac)和锰过氧化物酶(ManganesePeroxidase,MnP)的活性,记录菌丝在搔菌后的恢复情况。【结果】T在各个碳源的菌丝生长速度低于H,粉孢子等级在3-4级之间,SOD、CAT活性低于H,在栽培料中的Lac活性和MnP活性在第5天时与H相同,在第10、15、20天低于H。T在搔菌后菌丝恢复时间比H恢复时间长,恢复后的菌丝长势没有H长势浓密。【结论】通过探究金针菇原始菌株与退化菌株的菌丝生理生化特征,为判断金针菇菌株是否为退化菌株提供理论依据。 相似文献