全文获取类型
收费全文 | 547篇 |
免费 | 62篇 |
专业分类
609篇 |
出版年
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 22篇 |
2015年 | 31篇 |
2014年 | 31篇 |
2013年 | 33篇 |
2012年 | 55篇 |
2011年 | 35篇 |
2010年 | 25篇 |
2009年 | 14篇 |
2008年 | 33篇 |
2007年 | 24篇 |
2006年 | 30篇 |
2005年 | 27篇 |
2004年 | 26篇 |
2003年 | 25篇 |
2002年 | 24篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 8篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1971年 | 2篇 |
1968年 | 2篇 |
1929年 | 1篇 |
1925年 | 1篇 |
1922年 | 1篇 |
排序方式: 共有609条查询结果,搜索用时 0 毫秒
591.
592.
593.
Anders Riise Moen Kjersti Ruud Thorleif Anthonsen 《Journal of Molecular Catalysis .B, Enzymatic》2008,50(2-4):74-79
By employing a combination of stereospecific osmium catalyzed dihydroxylation of selected alkenes, and enantioselective lipase catalyzed kinetic resolution, nine alkenes were converted into nine enantiopure vicinal diols and nine enantiopure hydroxy butanoates. 相似文献
594.
Ruud RG Bueters Annelies Klaasen Lambertus P van den Heuvel Michiel F Schreuder 《Birth defects research. Part B, Developmental and reproductive toxicology》2013,98(6):486-492
The kidney is one of the key organs in clearing foreign compounds. The effects of drugs on the developing kidney are relatively unknown. We studied the direct effect of furosemide, hydrochlorothiazide, ibuprofen, and indomethacin on kidney development in an ex vivo embryonic kidney model. At embryonic day 13, metanephroi were dissected from mice and cultured in control media or media supplemented with various clinically relevant concentrations of drugs. The ureteric tree was visualized by whole‐mount staining and branching was evaluated by counting. Additionally, gene expression levels of Wt1, Sox9, Bmp7, Fgf8, and Gdnf were investigated. No distinct differences were noted on either ureteric tip development or gene expression analysis for each drug after 24 hr of exposure. Even though short‐term exposure to clinically relevant concentrations seems not to disturb renal development, future research is needed to study prolonged or repeated exposures. 相似文献
595.
Ruud van der Weele Ľuboš Hrivniak Jürgen Kappert Peter Manko Igor Shamshev 《法国昆虫学会纪事》2013,49(2):92-98
An inventory of species from families Brachystomatidae, Empididae and Hybotidae from random and non-intensive samplings from Uzh River Basin in the Ukraine is presented. Thirteen empidid species [Empis (E.) filata, Hemerodromia oratoria, Hilara flavipes, H. hyposeta, H. intermedia, H. lasiochira, H. litorea, H. media, Chelifera precatoria, C. trapezina, Rhamphomyia (Aclonempis) longipes, R. (Holoclera) nigripennis, Wiedemannia (W.) tricuspidata], and three hybotid species (Crossopalpus curvinervis, Oedalea stigmatella, Platypalpus longiseta) are recorded for the first time for the fauna of the Ukraine. Ukrainian checklists of these families are summarized for Brachystomatidae with two species, for Empididae with 57 species and for Hybotidae with 91 species. 相似文献
596.
High oxygen concentrations predispose mouse lungs to the deleterious effects of high stretch ventilation. 总被引:6,自引:0,他引:6
Timothy C Bailey Erica L Martin Lin Zhao Ruud A W Veldhuizen 《Journal of applied physiology》2003,94(3):975-982
Mechanical ventilation is a necessary intervention for patients with acute lung injury. However, mechanical ventilation can propagate acute lung injury and increase systemic inflammation. The exposure to >21% oxygen is often associated with mechanical ventilation yet has not been examined within the context of lung stretch. We hypothesized that mice exposed to >90% oxygen will be more susceptible to the deleterious effects of high stretch mechanical ventilation. C57B1/6 mice were randomized into 48-h exposure of 21 or >90% oxygen; mice were then killed, and isolated lungs were randomized into a nonstretch or an ex vivo, high-stretch mechanical ventilation group. Lungs were assessed for compliance and lavaged for surfactant analysis, and cytokine measurements or lungs were homogenized for surfactant-associated protein analysis. Mice exposed to >90% oxygen + stretch had significantly lower compliance, altered pulmonary surfactant, and increased inflammatory cytokines compared with all other groups. Our conclusion is that 48 h of >90% oxygen and high-stretch mechanical ventilation deleteriously affect lung function to a greater degree than stretch alone. 相似文献
597.
Mustafa Al-Saiedy Ryan Pratt Patrick Lai Evan Kerek Heidi Joyce Elmar Prenner Francis Green Chang-Chun Ling Ruud Veldhuizen Salim Ghandorah Matthias Amrein 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(4):1040-1049
Pulmonary surfactant forms a cohesive film at the alveolar air-lung interface, lowering surface tension, and thus reducing the work of breathing and preventing atelectasis. Surfactant function becomes impaired during inflammation due to degradation of the surfactant lipids and proteins by free radicals. In this study, we examine the role of reactive nitrogen (RNS) and oxygen (ROS) species on surfactant function with and without physiological cholesterol levels (5–10%). Surface activity was assessed in vitro in a captive bubble surfactometer (CBS). Surfactant chemistry, monolayer fluidity and thermodynamic behavior were also recorded before and after oxidation. We report that physiologic amounts of cholesterol combined with oxidation results in severe impairment of surfactant function. We also show that surfactant polyunsaturated phospholipids are the most susceptible to oxidative alteration. Membrane thermodynamic experiments showed significant surfactant film stiffening after free radical exposure in the presence of cholesterol. These results point to a previously unappreciated role for cholesterol in amplifying defects in surface activity caused by oxidation of pulmonary surfactant, a finding that may have implications for treating several lung diseases. 相似文献
598.
A method is presented which allows one to follow in a relative rapid and accurate way the synthesis of gene 5 protein of the bacteriophage M13 in a DNA-dependent cell-free system. Due to its unique property of binding selectively to single-stranded but not to double-stranded DNA, gene 5 protein can readily be separated, by means of sucrose densitygradient centrifugation, from the other polypeptides synthesized in the cell-free system. The meaning of this technique for the elucidation of the mechanism(s) which regulates gene 5 protein synthesis is discussed. 相似文献
599.
Ruud Kraayenhof Jaap J. Schuurmans Leen J. Valkier Jan P.C. Veen Daan Van Marum Carel G.G. Jasper 《Analytical biochemistry》1982,127(1):93-99
An improved design of a thermostatically controlled reaction cuvette for time-dependent biochemical measurements is described. The design is such that a multiple choice of single and simultaneous spectroscopic and electrode analyses can be performed in a sample of about 1.8 ml. This choice is quite flexible due to the use of exchangeable tapered plugs suited with either optical quartz-rod windows for absorption or fluorescence measurements or selective electrodes for changes of O2, H2, H+, etc. Temperature is accurately controlled by a thermoelectric (Peltier) module. An overhead constant-stirring device includes solute addition and gasflow ports. A bottom window allows actinic illumination for photobiological and photochemical experiments. Some examples of application in combination with commercial or laboratorymade instruments are presented. 相似文献
600.
Maryam?Hashemi Shabestari Cor?J.A.M. Wolfs Ruud?B. Spruijt Herbert van?Amerongen Martina Huber 《Biophysical journal》2014,106(6):1349-1358
The structure of the unusually long (∼100 amino-acid residues) N-terminal domain of the light-harvesting protein CP29 of plants is not defined in the crystal structure of this membrane protein. We studied the N-terminus using two electron paramagnetic resonance (EPR) approaches: the rotational diffusion of spin labels at 55 residues with continuous-wave EPR, and three sets of distances with a pulsed EPR method. The N-terminus is relatively structured. Five regions that differ considerably in their dynamics are identified. Two regions have low rotational diffusion, one of which shows α-helical character suggesting contact with the protein surface. This immobile part is flanked by two highly dynamic, unstructured regions (loops) that cover residues 10–22 and 82–91. These loops may be important for the interaction with other light-harvesting proteins. The region around residue 4 also has low rotational diffusion, presumably because it attaches noncovalently to the protein. This section is close to a phosphorylation site (Thr-6) in related proteins, such as those encoded by the Lhcb4.2 gene. Phosphorylation might influence the interaction with other antenna complexes, thereby regulating the supramolecular organization in the thylakoid membrane. 相似文献