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781.
Hye Ok Kang Chung Wook Chung Hyung Woo Kim Young Baek Kim Young Ha Rhee 《Antonie van Leeuwenhoek》2001,80(2):185-191
A newly isolated strain, designated as Pseudomonas sp. DSY-82, synthesized medium-chain-length polyhydroxyalkanoate (MCL-PHA) copolyesters when grown on alkanoates from hexanoate to undecanoate as the sole carbon source. When used alone, butyrate and valerate supported the growth of the isolate but not PHA production. However, unusual polyesters containing 3-hydroxyvalerate, as well as various MCL 3-hydroxyalkanoate monomeric units, were synthesized when valerate was cofed with either nonanoate or 10-undecenoate, suggesting the formation of monomer units from both substrates. Concentrations of 3-hydroxyvalerate, 3-hydroxyoctanoate, and 3-hydroxydecanoate in the PHAs produced were significantly elevated by the addition of valerate, indicating that the incorporation of these monomer units to PHA occurred primarily through cometabolism. The total amount of these monomer units in the PHAs reached up to 30%. The PHAs produced in this study were most likely random copolyesters as determined by differential scanning calorimetric analysis. This is the first case of microbial synthesis of copolyesters consisting of 3-hydroxyvalerate and MCL 3-hydroxyalkanoate monomer units through cometabolism. 相似文献
782.
Beffert U Nematollah Farsian F Masiulis I Hammer RE Yoon SO Giehl KM Herz J 《Current biology : CB》2006,16(24):2446-2452
A central pathogenic feature of neurodegenerative diseases and neurotrauma is the death of neurons. A mechanistic understanding of the factors and conditions that induce the dysfunction and death of neurons is essential for devising effective treatment strategies against neuronal loss after trauma or during aging. Because Apolipoprotein E (ApoE) is a major risk factor for several neurodegenerative diseases, including Alzheimer's disease , a direct or indirect role of ApoE receptors in the disease process is likely. Here we have used gene targeting in mice to investigate possible roles of ApoE receptors in the regulation of neuronal survival. We demonstrate that a differentially spliced isoform of an ApoE receptor, ApoE receptor 2 (Apoer2), is essential for protection against neuronal cell loss during normal aging. Furthermore, the same splice form selectively promotes neuronal cell death after injury through mechanisms that may involve serine/threonine kinases of the Jun N-terminal kinase (JNK) family. These findings raise the possibility that ApoE and its receptors cooperatively regulate common mechanisms that are essential to neuronal survival in the adult brain. 相似文献
783.
Lee SY Choi BH Hur EM Lee JH Lee SJ Lee CO Kim KT 《American journal of physiology. Cell physiology》2006,290(4):C1060-C1066
Norepinephrine (NE) is one of the major neurotransmitters that determine melatonin production in the pineal gland. Although a substantial amount of Ca2+ influx is triggered by NE, the Ca2+ entry pathway and its physiological relevance have not been elucidated adequately. Herein we report that the Ca2+ influx triggered by NE significantly regulates the protein level of serotonin N-acetyltransferase, or arylalkylamine N-acetyltransferase (AANAT), a critical enzyme in melatonin production, and is responsible for maintaining the Ca2+ response after repetitive stimulation. Ca2+ entry evoked by NE was dependent on PLC activation. NE evoked a substantial amount of Ca2+ entry even after cells were treated with 1-oleoyl-2-acetyl-sn-glycerol (OAG), an analog of diacylglycerol. To the contrary, further OAG treatment after cells had been exposed to OAG did not evoke additional Ca2+ entry. Moreover, NE failed to induce further Ca2+ entry after the development of Ca2+ entry induced by thapsigargin (Tg), suggesting that the pathway of Ca2+ entry induced by NE might be identical to that of Tg. Interestingly, Ca2+ entry evoked by NE or Tg induced membrane hyperpolarization that was reversed by iberiotoxin (IBTX), a specific inhibitor of large-conductance Ca2+-activated K+ (BK) channels. Moreover, IBTX-sensitive BK current was observed during application of NE, suggesting that activation of the BK channels was responsible for the hyperpolarization. Furthermore, the activation of BK channels triggered by NE contributed to regulation of the protein level of AANAT. Collectively, these results suggest that NE triggers Ca2+ entry coupled to BK channels and that NE-induced Ca2+ entry is important in the regulation of AANAT. serotonin N-acetyltransferase; pineal gland 相似文献
784.
Jeong LS Lee HW Kim HO Jung JY Gao ZG Duong HT Rao S Jacobson KA Shin DH Lee JA Gunaga P Lee SK Jin DZ Chun MW Moon HR 《Bioorganic & medicinal chemistry》2006,14(14):4718-4730
A large series of N6-substituted-4'-thioadenosines were synthesized starting from D-gulonic-gamma-lactone, and structure-activity relationships were studied at the human A3 and other subtypes of adenosine receptors (ARs). 2-Chloro-substituted and 2-H analogues were compared. 2-Chloro-N6-methyl-4'-thioadenosine 19b was a highly potent and selective agonist (Ki=0.8+/-0.1 nM in binding) at the A3AR, and displayed the same relative efficacy in receptor activation as a known full agonist, Cl-IB-MECA. Most of N6-substituted-4'-thioadenosines were less potent in binding than the corresponding N6-substituted-adenosines or N6-substituted-4'-thioadenosine-5'-uronamides. N6-(3-Iodobenzyl) derivative 19g was demonstrated to be an A3AR-selective partial agonist displaying a Ki value of 3.2 nM. 相似文献
785.
Lee JS Lim MO Cho KY Cho JH Chang SY Nam DH 《Journal of microbiology (Seoul, Korea)》2006,44(1):29-34
The purpose of this study was to develop molecular identification method for medical mushrooms and their preparations based on the nucleotide sequences of nuclear large subunit (LSU) rDNA. Four specimens were collected of each of the three representative medicinal mushrooms used in Korea: Ganoderma lucidum, Coriolus versicolor, and Fomes fomentarius. Fungal material used in these experiments included two different mycelial cultures and two different fruiting bodies from wild or cultivated mushrooms. The genomic DNA of mushrooms were extracted and 3 nuclear LSU rDNA fragments were amplified: set 1 for the 1.1-kb DNA fragment in the upstream region, set 2 for the 1.2-kb fragment in the middle, and set 3 for the 1.3-kb fragment downstream. The amplified gene products of nuclear large subunit rDNA from 3 different mushrooms were cloned into E. coli vector and subjected to nucleotide sequence determination. The sequence thus determined revealed that the gene sequences of the same medicinal mushroom species were more than 99.48% homologous, and the consensus sequences of 3 different medicinal mushrooms were more than 97.80% homologous. Restriction analysis revealed no useful restriction sites for 6-bp recognition enzymes for distinguishing the 3 sequences from one another, but some distinctive restriction patterns were recognized by the 4-bp recognition enzymes AccII and HhaI. This analysis was also confirmed by PCR-RFLP experiments on medicinal mushrooms. 相似文献
786.
Jung Hoon Choi Ki-Yeon Yoo Ok Kyu Park Choong Hyun Lee Sung Koo Kim In Koo Hwang Yun Lyul Lee Hyung-Cheul Shin Moo-Ho Won 《Cellular and molecular neurobiology》2010,30(6):929-938
Neurogenesis occurs during the embryonic stage and throughout life. Brain injuries such as ischemic insults enhance cell proliferation
in some areas of the brain. We examined proliferation of newly generated cells in each layer of the gerbil main olfactory
bulb (MOB) after 5 min of transient cerebral ischemia using bromodeoxyuridine (BrdU) immunohistochemistry. Ischemia-related
neuronal death in the MOB was not detected using Fluoro-Jade B histofluorescence and TUNEL staining. Many BrdU-positive (+) cells were found in the rostral migratory stream in control and ischemic MOBs. Significant increase of BrdU+ cells was observed in the granule cell layer (GCL) and glomerular layer (GL) from 15 days post-ischemia, and BrdU+ cells were very much higher than those of the control group 30 days post-ischemia. At this time point after ischemia/reperfusion,
a few BrdU+ cells in the GL and GCL were co-localized with calretinin+ cells, and many BrdU+ cells expressed doublecortin, a marker of immature neurons. These results indicate that cell proliferation is increased in
the GCL and GL without apparent neuronal loss from 15 days after transient cerebral ischemia in gerbils. 相似文献
787.
788.
Jin Hee Jung Jeong Ok Lee Ji Hae Kim Soo Kyung Lee Ga Young You Sun Hwa Park Ji Man Park Eung‐Kyun Kim Pann‐Ghill Suh Jin Kyung An Hyeon Soo Kim 《Journal of cellular physiology》2010,223(2):408-414
Quercetin, an anti‐oxidant flavonoid that is widely distributed in the plant kingdom, has been suggested to have chemopreventive effects on cancer cells, although the mechanism is not completely understood. In this study, we found that quercetin increased the phosphorylation of AMP‐activated protein kinase (AMPK) and downstream acetyl‐CoA carboxylase (ACC) and suppressed the viability of HeLa cells. AICAR, an AMPK activator, and quercetin down‐regulated heat shock protein (HSP)70 and increased the activity of the pro‐apoptotic effector, caspase 3. Knock‐down of AMPK blocked quercetin‐mediated HSP70 down‐regulation. Moreover, knock‐down of HSP70 enhanced quercetin‐mediated caspase 3 activation. Furthermore, quercetin sustained epidermal growth factor receptor (EGFR) activation by suppressing the phosphatases, PP2a and SHP‐2. Finally, quercetin increased the interaction between EGFR and Cbl, and also induced the tyrosine phosphorylation of Cbl. Together, these results suggest that quercetin may have anti‐tumor effects on HeLa cells via AMPK‐induced HSP70 and down‐regulation of EGFR. J. Cell. Physiol. 223: 408–414, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
789.
Young‐Ae Choi Dong‐Kyun Kim Ok‐Sun Bang Shin‐Sung Kang Eun‐Jung Jin 《Biology of the cell / under the auspices of the European Cell Biology Organization》2010,102(2):107-119
Background information. sPLA2 (secretory phospholipase A2) has been implicated in a wide range of cellular responses, including cell proliferation and ECM (extracellular matrix) remodelling. Even though ECM remodelling is an essential step for chondrogenesis, the expression and functions of sPLA2 during chondrogenesis have not been studied. Results. In the present study, for the first time, we detect the secretion of sPLA2 during limb development and suggest that sPLA2 influences the proliferation and/or survival of limb mesenchymal cells. Treatment of wing bud mesenchymal cells with exogenous sPLA2 promoted cell death by activating MMP‐9 (matrix metalloproteinase‐9) and increasing type I collagen degradation. The additive chondro‐inhibitory actions were induced by co‐treatment of mp‐BSA (p‐aminophenyl‐mannopyranoside‐BSA), a known ligand of the mannose receptor. Chondro‐inhibitory actions by sPLA2 were prevented by functional blocking of FcRY (chicken yolk sac IgY receptor), a mannose receptor family member that is the orthologue of the mammalian PLA2 (phospholipase A2) receptor and by inhibition of ERK (extracellular‐signal‐regulated kinase) activity. Conclusions. Taken together, our results suggest that elevated levels of sPLA2 secreted by wing bud mesenchymal cells promote type I collagen degradation by MMP‐9 in a manner typical of receptor‐mediated signalling and that these events lead to cell death. 相似文献