全文获取类型
收费全文 | 735篇 |
免费 | 54篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 16篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 20篇 |
2017年 | 19篇 |
2016年 | 27篇 |
2015年 | 39篇 |
2014年 | 39篇 |
2013年 | 49篇 |
2012年 | 68篇 |
2011年 | 69篇 |
2010年 | 43篇 |
2009年 | 25篇 |
2008年 | 50篇 |
2007年 | 42篇 |
2006年 | 44篇 |
2005年 | 56篇 |
2004年 | 50篇 |
2003年 | 37篇 |
2002年 | 29篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 6篇 |
1990年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有789条查询结果,搜索用时 839 毫秒
11.
Jie Zhang Satoshi Yamada Eri Ogihara Masahiro Kurita Norihiro Banno Wei Qu Feng Feng Toshihiro Akihisa 《化学与生物多样性》2016,13(11):1601-1609
Seven triterpenoids, 1 – 7 , two diarylheptanoids, 8 and 9 , four phenolic compounds, 10 – 13 , and three other compounds, 14 – 16 , were isolated from the hexane and MeOH extracts of the bark of Myrica cerifera L. (Myricaceae). Among these compounds, betulin ( 1 ), ursolic acid ( 3 ), and myricanol ( 8 ) exhibited cytotoxic activities against HL60 (leukemia), A549 (lung), and SK‐BR‐3 (breast) human cancer cell lines (IC50 3.1 – 24.2 μm ). Compound 8 induced apoptotic cell death in HL60 cells (IC50 5.3 μm ) upon evaluation of the apoptosis‐inducing activity by flow cytometric analysis and by Hoechst 33342 staining method. Western blot analysis on HL60 cells revealed that 8 activated caspases‐3, ‐8, and ‐9 suggesting that 8 induced apoptosis via both mitochondrial and death receptor pathways in HL60. Upon evaluation of the melanogenesis‐inhibitory activity in B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH), erythrodiol ( 7 ), 4‐hydroxy‐2‐methoxyphenyl β‐d ‐glucopyranoside ( 13 ), and butyl quinate ( 15 ) exhibited inhibitory effects (65.4 – 86.0% melanin content) with no, or almost no, toxicity to the cells (85.9 – 107.4% cell viability) at 100 μm concentration. In addition, 8 , myricanone ( 9 ), myricitrin ( 10 ), protocatechuic acid ( 11 ), and gallic acid ( 12 ) revealed potent DPPH radical‐scavenging activities (IC50 6.9 – 20.5 μm ). 相似文献
12.
Akiko Shibui Ayako Takamori Mohammed E.M. Tolba Aya Nambu Eri Shimura Sachiko Yamaguchi Chizu Sanjoba Hajime Suto Katsuko Sudo Ko Okumura Sumio Sugano Hideaki Morita Hirohisa Saito Kenji Matsumoto Susumu Nakae 《Biochemistry and Biophysics Reports》2016
IL-25, IL-33 and TSLP, which are produced predominantly by epithelial cells, can induce production of Th2-type cytokines such as IL-4, IL-5 and/or IL-13 by various types of cells, suggesting their involvement in induction of Th2-type cytokine-associated immune responses. It is known that Th2-type cytokines contribute to host defense against malaria parasite infection in mice. However, the roles of IL-25, IL-33 and TSLP in malaria parasite infection remain unclear. Thus, to elucidate this, we infected wild-type, IL-25?/?, IL-33?/? and TSLP receptor (TSLPR)?/? mice with Plasmodium berghei (P. berghei) ANKA, a murine malaria strain. The expression levels of IL-25, IL-33 and TSLP mRNA were changed in the brain, liver, lung and spleen of wild-type mice after infection, suggesting that these cytokines are involved in host defense against P. berghei ANKA. However, the incidence of parasitemia and survival in the mutant mice were comparable to in the wild-type mice. These findings indicate that IL-25, IL-33 and TSLP are not critical for host defense against P. berghei ANKA. 相似文献
13.
Many plants have mutualistic relationships with ants, whereby plants provide food and/or nesting sites for the symbiotic ants, and in turn the ants protect the host plants by excluding herbivores. While the ants are useful as guards, they may negatively affect host reproduction by excluding pollinators. Here we studied this potential conflict in the myrmecophytic Macaranga winkleri pollinated by the thrips Dolichothrips fialae. Behavioural responses of ant guards to pollinator thrips and their chemicals, and related chemical analyses, provide evidence that thrips deter ant-guards by secreting droplets containing ant-repelling n-decanoic acid from their anuses. This is the first report of insect pollinators repelling their host’s symbiotic guard ants to perform pollination. This is a novel strategy by which a plant host avoids interference with pollination by ant-guards in an ant–plant mutualism. The acquisition of a pollination system that is resistant to ant attacks may have facilitated the evolution of myrmecophytes in the genus Macaranga. 相似文献
14.
Cohesin is a ring‐shaped protein complex that plays a crucial role in sister chromatid cohesion and gene expression. The dynamic association of cohesin with chromatin is essential for these functions. However, the exact nature of cohesin dynamics, particularly cohesin translocation, remains unclear. We evaluated the dynamics of individual cohesin molecules on DNA and found that the cohesin core complex possesses an intrinsic ability to traverse DNA in an adenosine triphosphatase (ATPase)‐dependent manner. Translocation ability is suppressed in the presence of Wapl‐Pds5 and Sororin; this suppression is alleviated by the acetylation of cohesin and the action of mitotic kinases. In Xenopus laevis egg extracts, cohesin is translocated on unreplicated DNA in an ATPase‐ and Smc3 acetylation‐dependent manner. Cohesin movement changes from bidirectional to unidirectional when cohesin faces DNA replication; otherwise, it is incorporated into replicating DNA without being translocated or is dissociated from replicating DNA. This study provides insight into the nature of individual cohesin dynamics and the mechanisms by which cohesin achieves cohesion in different chromatin contexts. 相似文献
15.
Yosuke Kanno Akira Ishisaki Eri Kawashita Hiromi Kuretake Kanako Ikeda Osamu Matsuo 《International journal of biological sciences》2016,12(1):63-71
Chronic inflammatory diseases, such as rheumatoid arthritis and periodontitis-caused bone destruction, results from an increase of bone-resorbing osteoclasts (OCs) induced by inflammation. However, the detailed mechanisms underlying this disorder remain unclear. We herein investigated that the effect of urokinase-type plasminogen activator (uPA) on inflammatory osteoclastogenesis induced by lipopolysaccharide (LPS), which is a potent stimulator of bone resorption in inflammatory diseases. We found that the uPA deficiency promoted inflammatory osteoclastogenesis and bone loss induced by LPS. We also showed that LPS induced the expression of uPA, and the uPA treatment attenuated the LPS-induced inflammatory osteoclastogenesis of RAW264.7 mouse monocyte/macrophage lineage cells. Additionally, we showed that the uPA-attenuated inflammatory osteoclastgenesis is associated with the activation of plasmin/protease-activated receptor (PAR)-1 axis by uPA. Moreover, we examined the mechanism underlying the effect of uPA on inflammatory osteoclastogenesis, and found that uPA/plasmin/PAR-1 activated the adenosine monophosphate-activated protein kinase (AMPK) pathway through Ca2+/calmodulin dependent protein kinase kinase (CaMKK) activation, and attenuated inflammatory osteoclastogenesis by inactivation of NF-κB in RAW264.7 cells. These data suggest that uPA attenuated inflammatory osteoclastogenesis through the plasmin/PAR-1/Ca2+/CaMKK/AMPK axis. Our findings may provide a novel therapeutic approach to bone loss caused by inflammatory diseases. 相似文献
16.
Efficient modification of the myostatin gene in porcine somatic cells and generation of knockout piglets
下载免费PDF全文
![点击此处可从《Molecular reproduction and development》网站下载免费的PDF全文](/ch/ext_images/free.gif)
17.
Murakami Shinsuke Nakatani Jun Nakajima Kenichi Amasawa Eri Ii Ryota Hayashi Kiyotada Yoshikawa Naoki Daigo Ichiro Kishita Yusuke Ihara Tomohiko Shobatake Koichi Kudoh Yuki Motoshita Masaharu Kanemoto Keiichiro Hara Minako Kashiwagi Aiichiro Hashimoto Seiji Shigetomi Yosuke Kanzaki Masayuki Kikuchi Yasunori Ohno Hajime Fukushima Yasuhiro 《The International Journal of Life Cycle Assessment》2019,24(8):1544-1552
The International Journal of Life Cycle Assessment - 相似文献
18.
Naoki Yokokawa Emi Kikuchi‐Uehara Eri Amasawa Hirokazu Sugiyama Masahiko Hirao 《Journal of Industrial Ecology》2019,23(5):1253-1263
This study analyzed the environmental impacts of packaging‐derived changes in food production and consumer behavior to assist packaging designers in making environmentally conscious decisions. Packaging can be functionalized to prevent food loss and waste (FLW), for example, extending the expiration date and apportioning the package size, but it can generate additional environmental impacts from changes in food and packaging production. Previous studies assessed additional impacts from packaging production; however, the effects of packaging functionalization are yet to be connected with food production and consumer behavior. To examine the effect of functionalization on these aspects, we analyzed packaging‐derived changes in food production for milk and cabbage products. The case study compared products with functionalized packaging that permits a longer expiration date or a smaller portion size to their base‐case products. Our results showed that the packaging‐derived changes increased the global warming potential (GWP) of food production more than other processes did. Thus, changes in food production weakened the effectiveness of the packaging functionalization to decrease the GWP. Moreover, the analysis of consumer behavior scenarios showed that consumers’ perception of the expiration date decisively influences the effectiveness of packaging functionalization. When consumers discarded food after the expiration date, provided they consumed in small quantities, the packaging functionalization reduced FLW. From the scenario analysis, we identified appropriate combinations of packaging functionalization and consumer behaviors to effectively decrease total GWP. With our expanded analysis, packaging designers can understand the effectiveness of their decisions on the product life cycle in reducing FLW and environmental impacts. 相似文献
19.
Koyama Satoshi Fujita Hiroyuki Shimosato Takeshi Kamijo Aki Ishiyama Yasufumi Yamamoto Eri Ishii Yoshimi Hattori Yukako Hagihara Maki Yamazaki Etsuko Tomita Naoto Nakajima Hideaki 《Probiotics and antimicrobial proteins》2019,11(1):295-298
Probiotics and Antimicrobial Proteins - Probiotic-rich foods are consumed without much restriction. We report here, a case of septic shock caused by yogurt derived Lactobacillus species in a... 相似文献
20.
Yu Kitadate David J. Jörg Moe Tokue Ayumi Maruyama Rie Ichikawa Soken Tsuchiya Eri Segi-Nishida Toshinori Nakagawa Aya Uchida Chiharu Kimura-Yoshida Seiya Mizuno Fumihiro Sugiyama Takuya Azami Masatsugu Ema Chiyo Noda Satoru Kobayashi Isao Matsuo Yoshiakira Kanai Shosei Yoshida 《Cell Stem Cell》2019,24(1):79-92.e6