全文获取类型
收费全文 | 1583篇 |
免费 | 140篇 |
出版年
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 25篇 |
2020年 | 13篇 |
2019年 | 19篇 |
2018年 | 12篇 |
2017年 | 19篇 |
2016年 | 35篇 |
2015年 | 59篇 |
2014年 | 50篇 |
2013年 | 83篇 |
2012年 | 103篇 |
2011年 | 126篇 |
2010年 | 72篇 |
2009年 | 60篇 |
2008年 | 104篇 |
2007年 | 96篇 |
2006年 | 99篇 |
2005年 | 88篇 |
2004年 | 83篇 |
2003年 | 104篇 |
2002年 | 86篇 |
2001年 | 15篇 |
2000年 | 8篇 |
1999年 | 16篇 |
1998年 | 19篇 |
1997年 | 18篇 |
1996年 | 9篇 |
1995年 | 14篇 |
1994年 | 18篇 |
1993年 | 24篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 23篇 |
1982年 | 20篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1975年 | 7篇 |
1973年 | 5篇 |
1970年 | 6篇 |
排序方式: 共有1723条查询结果,搜索用时 15 毫秒
991.
992.
Elizabeth O'Day Minh T. N. Le Shunsuke Imai Shen Mynn Tan Rory Kirchner Haribabu Arthanari Oliver Hofmann Gerhard Wagner Judy Lieberman 《The Journal of biological chemistry》2015,290(29):17909-17922
Lin28 is an evolutionarily conserved RNA-binding protein that inhibits processing of pre-let-7 microRNAs (miRNAs) and regulates translation of mRNAs that control developmental timing, pluripotency, metabolism, and tumorigenesis. The RNA features that mediate Lin28 binding to the terminal loops of let-7 pre-miRNAs and to Lin28-responsive elements (LREs) in mRNAs are not well defined. Here we show that Lin28 target datasets are enriched for RNA sequences predicted to contain stable planar structures of 4 guanines known as G-quartets (G4s). The imino NMR spectra of pre-let-7 loops and LREs contain resonances characteristic of G4 hydrogen bonds. These sequences bind to a G4-binding fluorescent dye, N-methyl-mesoporphyrin IX (NMM). Mutations and truncations in the RNA sequence that prevent G4 formation also prevent Lin28 binding. The addition of Lin28 to a pre-let-7 loop or an LRE reduces G4 resonance intensity and NMM binding, suggesting that Lin28 may function to remodel G4s. Further, we show that NMM inhibits Lin28 binding. Incubation of a human embryonal carcinoma cell line with NMM reduces its stem cell traits. In particular it increases mature let-7 levels, decreases OCT4, HMGA1, CCNB1, CDK4, and Lin28A protein, decreases sphere formation, and inhibits colony formation. Our results suggest a previously unknown structural feature of Lin28 targets and a new strategy for manipulating Lin28 function. 相似文献
993.
Yusuke Komiya Judy E. Anderson Mariko Akahoshi Mako Nakamura Ryuichi Tatsumi Yoshihide Ikeuchi Wataru Mizunoya 《Analytical biochemistry》2015
To attain a superior in vitro model of mature muscle fibers, we modified the established protocol for isolating single muscle fibers from rat skeletal muscle. Muscle fiber cultures with high viability were obtained using flexor digitorum brevis muscle and lasted for at least 7 days. We compared the expression levels of adult myosin heavy chain (MyHC) isoforms in these single muscle fibers with myotubes formed from myoblasts; isolated fibers contained markedly more abundant adult MyHC isoforms than myotubes. This muscle fiber model, therefore, will be useful for studying the various functions and cellular processes of mature muscles in vitro. 相似文献
994.
995.
Alexis R. Demonbreun Kaitlin E. Swanson Ann E. Rossi H. Kieran Deveaux Judy U. Earley Madison V. Allen Priyanka Arya Sohinee Bhattacharyya Hamid Band Peter Pytel Elizabeth M. McNally 《PloS one》2015,10(9)
We previously showed that Eps15 homology domain-containing 1 (EHD1) interacts with ferlin proteins to regulate endocytic recycling. Myoblasts from Ehd1-null mice were found to have defective recycling, myoblast fusion, and consequently smaller muscles. When expressed in C2C12 cells, an ATPase dead-EHD1 was found to interfere with BIN1/amphiphysin 2. We now extended those findings by examining Ehd1-heterozygous mice since these mice survive to maturity in normal Mendelian numbers and provide a ready source of mature muscle. We found that heterozygosity of EHD1 was sufficient to produce ectopic and excessive T-tubules, including large intracellular aggregates that contained BIN1. The disorganized T-tubule structures in Ehd1-heterozygous muscle were accompanied by marked elevation of the T-tubule-associated protein DHPR and reduction of the triad linker protein junctophilin 2, reflecting defective triads. Consistent with this, Ehd1-heterozygous muscle had reduced force production. Introduction of ATPase dead-EHD1 into mature muscle fibers was sufficient to induce ectopic T-tubule formation, seen as large BIN1 positive structures throughout the muscle. Ehd1-heterozygous mice were found to have strikingly elevated serum creatine kinase and smaller myofibers, but did not display findings of muscular dystrophy. These data indicate that EHD1 regulates the maintenance of T-tubules through its interaction with BIN1 and links T-tubules defects with elevated creatine kinase and myopathy. 相似文献
996.
Studies of dietary fat absorption are generally conducted by using an animal model equipped with a lymph cannula. Although this animal model is widely accepted as the in vivo model of dietary fat absorption, the surgical techniques involved are challenging and expensive. Genetic manipulation of the animal model is also costly and time consuming. The alternative in vitro model is arguably more affordable, timesaving, and less challenging. Importantly, the in vitro model allows investigators to examine the enterocytes as an isolated system, reducing the complexity inherent in the whole organism model. This paper describes how human colon carcinoma cells (Caco-2) can serve as an in vitro model to study the enterocyte transport of lipids, and lipid-soluble drugs and vitamins. It explains the proper maintenance of Caco-2 cells and the preparation of their lipid mixture; and it further discusses the valuable option of using the permeable membrane system. Since differentiated Caco-2 cells are polarized, the main advantage of using the permeable membrane system is that it separates the apical from the basolateral compartment. Consequently, the lipid mixture can be added to the apical compartment while the lipoproteins can be collected from the basolateral compartment. In addition, the effectiveness of the lentivirus expression system in upregulating gene expression in Caco-2 cells is discussed. Lastly, this paper describes how to confirm the successful isolation of intestinal lipoproteins by transmission electron microscopy (TEM). 相似文献
997.
Michael Hornsby Marcin Paduch Shane Miersch Annika S??f Tet Matsuguchi Brian Lee Karolina Wypisniak Allison Doak Daniel King Svitlana Usatyuk Kimberly Perry Vince Lu William Thomas Judy Luke Jay Goodman Robert J. Hoey Darson Lai Carly Griffin Zhijian Li Franco J. Vizeacoumar Debbie Dong Elliot Campbell Stephen Anderson Nan Zhong Susanne Gr?slund Shohei Koide Jason Moffat Sachdev Sidhu Anthony Kossiakoff James Wells 《Molecular & cellular proteomics : MCP》2015,14(10):2833-2847
998.
Eric S. Cole Thomas H. Giddings Jr. Courtney Ozzello Mark Winey Eileen O'Toole Judy Orias Eileen Hamilton Sabrice Guerrier Anna Ballard Tyler Aronstein 《Eukaryotic cell》2015,14(2):116-127
Using serial-section transmission electron microscopy and three-dimensional (3D) electron tomography, we characterized membrane dynamics that accompany the construction of a nuclear exchange junction between mating cells in the ciliate Tetrahymena thermophila. Our methods revealed a number of previously unknown features. (i) Membrane fusion is initiated by the extension of hundreds of 50-nm-diameter protrusions from the plasma membrane. These protrusions extend from both mating cells across the intercellular space to fuse with membrane of the mating partner. (ii) During this process, small membrane-bound vesicles or tubules are shed from the plasma membrane and into the extracellular space within the junction. The resultant vesicle-filled pockets within the extracellular space are referred to as junction lumens. (iii) As junction lumens fill with extracellular microvesicles and swell, the plasma membrane limiting these swellings undergoes another deformation, pinching off vesicle-filled vacuoles into the cytoplasm (reclamation). (iv) These structures (resembling multivesicular bodies) seem to associate with autophagosomes abundant near the exchange junction. We propose a model characterizing the membrane-remodeling events that establish cytoplasmic continuity between mating Tetrahymena cells. We also discuss the possible role of nonvesicular lipid transport in conditioning the exchange junction lipid environment. Finally, we raise the possibility of an intercellular signaling mechanism involving microvesicle shedding and uptake. 相似文献
999.
Armon Sharei Radiana Trifonova Siddharth Jhunjhunwala George C. Hartoularos Alexandra T. Eyerman Abigail Lytton-Jean Mathieu Angin Siddhartha Sharma Roberta Poceviciute Shirley Mao Megan Heimann Sophia Liu Tanya Talkar Omar F. Khan Marylyn Addo Ulrich H. von Andrian Daniel G. Anderson Robert Langer Judy Lieberman Klavs F. Jensen 《PloS one》2015,10(4)
Intracellular delivery of biomolecules, such as proteins and siRNAs, into primary immune cells, especially resting lymphocytes, is a challenge. Here we describe the design and testing of microfluidic intracellular delivery systems that cause temporary membrane disruption by rapid mechanical deformation of human and mouse immune cells. Dextran, antibody and siRNA delivery performance is measured in multiple immune cell types and the approach’s potential to engineer cell function is demonstrated in HIV infection studies. 相似文献
1000.
Ghio AJ Turi JL Madden MC Dailey LA Richards JD Stonehuerner JG Morgan DL Singleton S Garrick LM Garrick MD 《American journal of physiology. Lung cellular and molecular physiology》2007,292(1):L134-L143
We tested the hypothesis that oxidative stress and biological effect after ozone (O3) exposure are dependent on changes in iron homeostasis. After O3 exposure, healthy volunteers demonstrated increased lavage concentrations of iron, transferrin, lactoferrin, and ferritin. In normal rats, alterations of iron metabolism after O3 exposure were immediate and preceded the inflammatory influx. To test for participation of this disruption in iron homeostasis in lung injury following O3 inhalation, we exposed Belgrade rats, which are functionally deficient in divalent metal transporter 1 (DMT1) as a means of iron uptake, and controls to O3. Iron homeostasis was disrupted to a greater extent and the extent of injury was greater in Belgrade rats than in control rats. Nonheme iron and ferritin concentrations were higher in human bronchial epithelial (HBE) cells exposed to O3 than in HBE cells exposed to filtered air. Aldehyde generation and IL-8 release by the HBE cells was also elevated following O3 exposure. Human embryonic kidney (HEK 293) cells with elevated expression of a DMT1 construct were exposed to filtered air and O3. With exposure to O3, elevated DMT1 expression diminished oxidative stress (i.e., aldehyde generation) and IL-8 release. We conclude that iron participates critically in the oxidative stress and biological effects after O3 exposure. 相似文献