全文获取类型
收费全文 | 4952篇 |
免费 | 407篇 |
国内免费 | 109篇 |
专业分类
5468篇 |
出版年
2023年 | 37篇 |
2022年 | 83篇 |
2021年 | 174篇 |
2020年 | 128篇 |
2019年 | 163篇 |
2018年 | 199篇 |
2017年 | 138篇 |
2016年 | 188篇 |
2015年 | 258篇 |
2014年 | 291篇 |
2013年 | 389篇 |
2012年 | 399篇 |
2011年 | 336篇 |
2010年 | 223篇 |
2009年 | 189篇 |
2008年 | 243篇 |
2007年 | 208篇 |
2006年 | 215篇 |
2005年 | 186篇 |
2004年 | 172篇 |
2003年 | 161篇 |
2002年 | 157篇 |
2001年 | 132篇 |
2000年 | 98篇 |
1999年 | 97篇 |
1998年 | 51篇 |
1997年 | 35篇 |
1996年 | 36篇 |
1995年 | 28篇 |
1994年 | 15篇 |
1993年 | 21篇 |
1992年 | 30篇 |
1991年 | 26篇 |
1990年 | 23篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1987年 | 24篇 |
1986年 | 18篇 |
1985年 | 25篇 |
1984年 | 20篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1979年 | 16篇 |
1978年 | 15篇 |
1977年 | 14篇 |
1975年 | 11篇 |
1974年 | 10篇 |
1973年 | 11篇 |
1972年 | 12篇 |
1971年 | 12篇 |
排序方式: 共有5468条查询结果,搜索用时 0 毫秒
111.
112.
Evelyn Walenta Ariane R. Pessentheiner Helmut J. Pelzmann Alexander Deutsch Madeleine Goeritzer Dagmar Kratky Hubert Hackl Da Young Oh Andreas Prokesch Juliane G. Bogner-Strauss 《PloS one》2013,8(11)
Our knowledge about adipocyte metabolism and development is steadily growing, yet many players are still undefined. Here, we show that α/β-hydrolase domain containing protein 15 (Abhd15) is a direct and functional target gene of peroxisome proliferator-activated receptor gamma (PPARγ), the master regulator of adipogenesis. In line, Abhd15 is mainly expressed in brown and white adipose tissue and strongly upregulated during adipogenesis in various murine and human cell lines. Stable knockdown of Abhd15 in 3T3-L1 cells evokes a striking differentiation defect, as evidenced by low lipid accumulation and decreased expression of adipocyte marker genes. In preconfluent cells, knockdown of Abhd15 leads to impaired proliferation, which is caused by apoptosis, as we see an increased SubG1 peak, caspase 3/7 activity, and BAX protein expression as well as a reduction in anti-apoptotic BCL-2 protein. Furthermore, apoptosis-inducing amounts of palmitic acid evoke a massive increase of Abhd15 expression, proposing an apoptosis-protecting role for ABHD15. On the other hand, in mature adipocytes physiological (i.e. non-apoptotic) concentrations of palmitic acid down-regulate Abhd15 expression. Accordingly, we found that the expression of Abhd15 in adipose tissue is reduced in physiological situations with high free fatty acid levels, like high-fat diet, fasting, and aging as well as in genetically obese mice. Collectively, our results position ABHD15 as an essential component in the development of adipocytes as well as in apoptosis, thereby connecting two substantial factors in the regulation of adipocyte number and size. Together with its intricate regulation by free fatty acids, ABHD15 might be an intriguing new target in obesity and diabetes research. 相似文献
113.
Mikovski Andréia Izabel da Silva Nayara Tayane Silva Lázara Aline Simões Machado Mariana de Souza Barbosa Lília Cristina Reis Aryane Campos de Matos Elyabe Monteiro Viccini Lyderson Facio da Silva Souza Claudinei Machado Marcelo Dias Otoni Wagner Campos de Carvalho Ilio Fealho Rocha Diego Ismael da Silva Maurecilne Lemes 《Plant Cell, Tissue and Organ Culture》2021,145(2):239-259
Plant Cell, Tissue and Organ Culture (PCTOC) - Somaclonal variation during in vitro culture is often an undesirable phenomenon but may also be a source of genetic variation useful for breeders. The... 相似文献
114.
Aurelien Dugourd Christoph Kuppe Marco Sciacovelli Enio Gjerga Attila Gabor Kristina B. Emdal Vitor Vieira Dorte B. BekkerJensen Jennifer Kranz Eric.M.J. Bindels Ana S.H. Costa Abel Sousa Pedro Beltrao Miguel Rocha Jesper V. Olsen Christian Frezza Rafael Kramann Julio SaezRodriguez 《Molecular systems biology》2021,17(1)
115.
116.
Correa Lda R Troleis J Mastroberti AA Mariath JE Fett-Neto AG 《Plant biology (Stuttgart, Germany)》2012,14(1):100-109
The literature describes different rooting protocols for Arabidopsis thaliana as models to study adventitious rooting, and results are generally perceived as comparable. However, there is a lack of investigations focusing on the distinct features, advantages and limitations of each method in the study of adventitious rooting with both wild-type (WT) ecotypes and their respective mutants. This investigation was undertaken to evaluate the adventitious rooting process in three different experimental systems, all using A. thaliana, analysing the same rooting parameters after transient exposure to auxin (indole-3-acetic acid) and control conditions: excised leaves, de-rooted plants and etiolated seedlings. The founding tissues and sites of origin of roots differed depending on the system used, whereas all rooting patterns were of the direct type (i.e., without callus formation). None of the systems had an absolute requirement for exogenous auxin, although rooting was enhanced by this phytohormone, with the exception of de-rooted plants, which had adventitious rooting strongly inhibited by exogenous auxin. Root elongation was much favoured in isolated leaves. Auxin-overproducing mutants could not be used in the detached leaf system due to precocious senescence; in the de-rooted plant system, these mutants had a WT-like rooting response, whereas the expression of the 'rooty' phenotype was only evident in the etiolated seedling system. Adventitious rooting of etiolated WT seedlings in the presence of exogenous auxin was inhibited by exogenous flavonoids, which act as auxin transport inhibitors; surprisingly, the flavonoid-deficient mutant chs had a lower rooting response compared to WT. Although Arabidopsis is an excellent model system to study adventitious rooting, physiological and developmental responses differed significantly, underlining the importance of avoiding data generalisation on rooting responses derived from different experimental systems with this species. 相似文献
117.
118.
花生四烯酸代谢相关酶环加氧酶(COX)、脂氧合酶(LOX)和活化的胞外信号调节激酶(p-ERK1/2)等与乳腺癌发生发展具有密切关系.为了进一步阐明它们在乳腺癌转移中的作用及其分子机制,应用反转录PCR(RT-PCR)、免疫印迹和免疫组化等方法,分别检测了乳腺癌细胞系、乳腺癌组织、癌旁组织和转移淋巴结组织中COX-2、5-LOX、12R-LOX、cPLA2和p-ERK1/2的表达水平.结果显示,与对照组相比,在具有高转移潜能的乳腺癌LM MCF-7细胞和MDA-MB-231细胞以及转移淋巴结组织中,COX-2、5-LOX、12R-LOX、cPLA2和p-ERK1/2均有较高水平表达.进而发现,p-ERK1/2的特异性抑制剂PD98059可拮抗LM-MCF-7细胞和MDA-MB-231细胞中COX-2、5-LOX、12R-LOX和cPLA2的高表达.上述结果表明,p-ERK1/2可以通过促进花生四烯酸代谢相关酶的表达促进乳腺癌细胞发生转移. 相似文献
119.
120.
高致病性禽流感防控难点的分析 总被引:1,自引:0,他引:1
禽流感(avian influenza,AI)是由禽流感病毒引起的一种严重危害畜牧业的急性传染病,特别是高致病性禽流感引起禽类的呼吸系统感染以及全身性败血症,死亡率极高。多年来,许多国家和地区都爆发过此病,造成巨大经济损失,而2004年亚洲爆发的H5N1亚型禽流感造成经济损失的同时还出现了众多的禽流感病毒直接感染人类、造成人员死亡病例,再一次把人类的目光转移向此病。AI抗原类型众多,变异频繁,不同的类型抗原之间无交叉反应,同时,病毒具有复杂的感染和复制机制以及复杂的传播网络等多种因素单独和,协同作用,导致高致病性禽流感防控困难。 相似文献