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901.
Comparative study on the inhibition of acetylcholinesterase activity in the freshwater fish Cyprinus carpio by mercury and zinc. 总被引:2,自引:0,他引:2
A Suresh B Sivaramakrishna P C Victoriamma K Radhakrishnaiah 《Biochemistry international》1992,26(2):367-375
The effects of sublethal concentrations of mercury (0.1mg/l) and zinc (6 mg/l) on acetylcholinesterase activity and acetylcholine content of gill, kidney, intestine, brain, liver and muscle of the freshwater fish Cyprinus carpio at 1, 15 and 30 days of exposure were studied. A significant suppression in acetylcholinesterase activity was recorded in all the organs from both mercury and zinc intoxicated fish at all the exposure periods. Concurrently, a significant increase in the content of acetylcholine in the organs was observed. These changes observed in the organs of mercury treated fish in different exposure periods were in the order 1 greater than 15 less than 30 days and in zinc treated fish 1 greater than 15 greater than 30 days. Further, these changes were greater in magnitude in the brain, liver and muscle (non-osmoregulatory organs) than in the gill, kidney and intestine (osmoregulatory organs) in both metal media. 相似文献
902.
Rattan SI 《Biological chemistry》2008,389(3):267-272
Aging at the molecular level is characterized by the progressive accumulation of molecular damage. The sources of damage act randomly through environmental and metabolically generated free radicals, through spontaneous errors in biochemical reactions, and through nutritional components. However, damage to a macromolecule may depend on its structure, localization and interactions with other macromolecules. Damage to the maintenance and repair pathways comprising homeodynamic machinery leads to age-related failure of homeodynamics, increased molecular heterogeneity, altered cellular functioning, reduced stress tolerance, diseases and ultimate death. Novel approaches for testing and developing effective means of intervention, prevention and modulation of aging involve means to minimize the occurrence and accumulation of molecular damage. Mild stress-induced hormesis by physical, biological and nutritional methods, including hormetins, represents a promising strategy for achieving healthy aging and for preventing age-related diseases. 相似文献
903.
G protein‐coupled receptors (GPCRs) are a vital class of proteins that transduce biological signals across the cell membrane. However, their allosteric activation mechanism is not fully understood; crystal structures of active and inactive receptors have been reported, but the functional pathway between these two states remains elusive. Here, we use structure‐based (Gō‐like) models to simulate activation of two GPCRs, rhodopsin and the β2 adrenergic receptor (β2AR). We used data‐derived reaction coordinates that capture the activation mechanism for both proteins, showing that activation proceeds through quantitatively different paths in the two systems. Both reaction coordinates are determined from the dominant concerted motions in the simulations so the technique is broadly applicable. There were two surprising results. First, the main structural changes in the simulations were distributed throughout the transmembrane bundle, and not localized to the obvious areas of interest, such as the intracellular portion of Helix 6. Second, the activation (and deactivation) paths were distinctly nonmonotonic, populating states that were not simply interpolations between the inactive and active structures. These transitions also suggest a functional explanation for β2AR's basal activity: it can proceed through a more broadly defined path during the observed transitions. Proteins 2014; 82:2538–2551. © 2014 Wiley Periodicals, Inc. 相似文献
904.
905.
Specific binding of [3H]-dexamethasone by the cytoplasmic fraction of normal human gingiva was carried out. Different concentrations of [3H]-dexamethasone were used with or without cold dexamethasone to determine the binding. Binding data by Scatchard plot yielded a straight line indicating a single class of specific receptors with equilibrium dissociation constant of 1.39 x 10(-9) M and B max of 80 fmol/mg protein. The proteins satisfied the high affinity and low capacity requirements of receptor. 相似文献
906.
Yuankun Zhai Jyotirmaya Behera Suresh C. Tyagi Neetu Tyagi 《Journal of cellular physiology》2019,234(10):18602-18614
Homocysteine (Hcy) is detrimental to bone health in a mouse model of diet-induced hyperhomocysteinemia (HHcy). However, little is known about Hcy-mediated osteoblast dysfunction via mitochondrial oxidative damage. Hydrogen sulfide (H2S) has potent antioxidant, anti-inflammatory, and antiapoptotic effects. In this study, we hypothesized that the H2S mediated recovery of osteoblast dysfunction by maintaining mitochondrial biogenesis in Hcy-treated osteoblast cultures in vitro. MC3T3-E1 osteoblastic cells were exposed to Hcy treatment in the presence or absence of an H2S donor (NaHS). Cell viability, osteogenic differentiation, reactive oxygen species (ROS) production were determined. Mitochondrial DNA copy number, adenosine triphosphate (ATP) production, and oxygen consumption were also measured. Our results demonstrated that administration of Hcy increases the intracellular Hcy level and decreases intracellular H2S level and expression of the cystathionine β-synthase/Cystathionine γ-lyase system, thereby inhibiting osteogenic differentiation. Pretreatment with NaHS attenuated Hcy-induced mitochondrial toxicity (production of total ROS and mito-ROS, ratio of mitochondrial fission (DRP-1)/fusion (Mfn-2)) and restored ATP production and mitochondrial DNA copy numbers as well as oxygen consumption in the osteoblast as compared with the control, indicating its protective effects against Hcy-induced mitochondrial toxicity. In addition, NaHS also decreased the release of cytochrome c from the mitochondria to the cytosol, which induces cell apoptosis. Finally, flow cytometry confirmed that NaHS can rescue cells from apoptosis induced by Hcy. Our studies strongly suggest that NaHS has beneficial effects on mitochondrial toxicity, and could be developed as a potential therapeutic agent against HHcy-induced mitochondrial dysfunction in cultured osteoblasts in vitro. 相似文献
907.
908.
The crystal structures of the complexes of L and DL histidine with formic acid have been determined as part of an effort to
define biologically and evolutionarily important interactions and aggregation patterns. In terms of ionization state and stoichiometry
they may be described as L-histidine formate formic acid and DL-histidine formate monohydrate respectively. In the L-histidine
complex, amino acid molecules arranged in head-to-tail sequences centred around 21 screw axes are interconnected by formic acid molecules and formate ions. Histidine-formate interactions in the structure
gives rise to a characteristic interaction pattern involving a linear array of alternating imidazole groups and formate ions.
In DL-histidine formale monohydrate, head-to-tail sequences involving glide related molecules are interconnected through main
chain-side chain interactions leading to amino acid layers. The layers are held together by formate ions and water molecules
arranged in strings along which the ion and the molecule alternate. The patterns of amino acid aggregation in histidine complexes
exhibit considerably higher variability than those in complexes involving arginine and lysine do.
X-ray studies on crystalline complexes involving amino and peptides Part XXIX. 相似文献
909.
Ananda Kuppanna Gopi Hosahudya N. Suresh Babu Vommina V. 《International journal of peptide research and therapeutics》1998,5(4):277-283
Summary Several Fmoc-α,α-dialkylamino acids and their acid chlorides have been prepared, isolated and characterised. The synthesis
of peptides containing sterically hindered dialkylamino acids has been accomplished using acid chloride/KOBt in dichloromethane.
The yields as well as the purity of the peptides were satistactory. 相似文献
910.
Kanchan Jhaver Asit De Suresh Advani Jayshree Nadkarni 《Cancer immunology, immunotherapy : CII》1991,34(2):123-127
Summary Peripheral blood monocytes from non-Hodgkin's lymphoma (NHL) patients were assessed for the monocyte functions with respect to their ability to secrete interleukin-1 and tumour necrosis factor (TNF) and their cytotoxic potential to tumour target WEHI 164 clone 13. Our results indicate comparable levels of interleukin-1 and TNF production by NHL patients. The cytotoxic potential by monocytes was also not depressed in these patients. The data obtained suggest normal monocyte functions in NHL patients. 相似文献