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61.
NPY-mRNA expressions in the nucleus accumbens,caudate putamen and cerebral cortex of apomorphine-susceptible and apomorphine-unsusceptible rats 总被引:1,自引:0,他引:1
Using the apomorphine-induced stereotyped gnawing response as a selection criterion, two distinct groups of rats can be distinguished, apomorphine-susceptible (APO-SUS) and apomorphine-unsusceptible (APO-UNSUS) rats. These two lines differ in several components of both striatal and extrastriatal areas. This study deals with the expression of neuropeptide Y (NPY)mRNA-expressing neurons in the nucleus accumbens, caudate putamen and cerebral cortex of both rat lines, using non-radioactive in situ hybridisation. The morphology of the neurons in the three regions is similar, viz. oblong, rectangular or triangular, with two or three processes. The neurons are homogeneously distributed in all regions, and in the nucleus accumbens they are particularly numerous ventrally to the anterior commissure. Using automated image analysis, the mean numerical density of NPYmRNA-positive neurons per brain region and the mean NPYmRNA expression level per neuron per brain region were determined. No differences appear in the numerical densities of NPYmRNA-containing neurons in the nucleus accumbens, caudate putamen and cortex between APO-SUS and APO-UNSUS rats. However, distinct differences between the rat lines are present in the level of NPYmRNA expression per neuron in the nucleus accumbens and in the caudate putamen, showing that NPY contributes to the differential neurochemical make-up of these rat lines that is responsible for their obvious differences in behaviour, physiology and immune competence. 相似文献
62.
Ilse Stevens Veerle Janssens Ellen Martens Stephen Dilworth Jozef Goris Christine Van Hoof 《European journal of biochemistry》2003,270(2):376-387
Protein phosphatase 2A is a phosphoserine/threonine phosphatase implicated in many cellular processes. The core enzyme comprises a catalytic and a PR65/A-subunit. The substrate specificity and subcellular localization are determined by a third regulatory B-subunit (PR55/B, PR61/B' and PR72/130/B"). To identify the proteins of the B" family in Xenopus laevis oocytes, a prophase Xenopus oocyte cDNA library was screened using human PR130 cDNA as a probe. Three different classes of cDNAs were isolated. One class is very similar to human PR130 and is probably the Xenopus orthologue of PR130 (XPR130). A second class of clones (XN73) is identical to the N-terminal part of XPR130 but ends a few amino acids downstream of the putative splicing site of PR130. To investigate how this occurs, the genomic structure of the human PR130 gene was determined. This novel protein does not act as a PP2A subunit but might compete with the function of PR130. The third set of clones (XPR70) is very similar to human PR48 but has an N-terminal extension. Further analysis of the human EST-database and the human PR48 gene structure, revealed that the human PR48 clone published is incomplete. The Xenopus orthologue of PR48 encodes a protein of 70 kDa which like the XPR130, interacts with the A-subunit in GST pull-down assays. XPR70 is ubiquitously expressed in adult tissues and oocytes whereas expression of XPR130 is very low in brain and oocytes. Expression of XN73 mainly parallels XPR130 with the exception of the brain. 相似文献
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Coppock EA Martens JR Tamkun MM 《American journal of physiology. Lung cellular and molecular physiology》2001,281(1):L1-12
The hypoxia-induced membrane depolarization and subsequent constriction of small resistance pulmonary arteries occurs, in part, via inhibition of vascular smooth muscle cell voltage-gated K+ (KV) channels open at the resting membrane potential. Pulmonary arterial smooth muscle cell KV channel expression, antibody-based dissection of the pulmonary arterial smooth muscle cell K+ current, and the O2 sensitivity of cloned KV channels expressed in heterologous expression systems have all been examined to identify the molecular components of the pulmonary arterial O2-sensitive KV current. Likely components include Kv2.1/Kv9.3 and Kv1.2/Kv1.5 heteromeric channels and the Kv3.1b alpha-subunit. Although the mechanism of KV channel inhibition by hypoxia is unknown, it appears that KV alpha-subunits do not sense O2 directly. Rather, they are most likely inhibited through interaction with an unidentified O2 sensor and/or beta-subunit. This review summarizes the role of KV channels in hypoxic pulmonary vasoconstriction, the recent progress toward the identification of KV channel subunits involved in this response, and the possible mechanisms of KV channel regulation by hypoxia. 相似文献
66.
Pivotal role of the non-hr origin of DNA replication in the genesis of defective interfering baculoviruses
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Pijlman GP Dortmans JC Vermeesch AM Yang K Martens DE Goldbach RW Vlak JM 《Journal of virology》2002,76(11):5605-5611
The generation of deletion mutants, including defective interfering viruses, upon serial passage of Spodoptera exigua multicapsid nucleopolyhedrovirus (SeMNPV) in insect cell culture has been studied. Sequences containing the non-homologous region origin of DNA replication (non-hr ori) became hypermolar in intracellular viral DNA within 10 passages in Se301 insect cells, concurrent with a dramatic drop in budded virus and polyhedron production. These predominant non-hr ori-containing sequences accumulated in larger concatenated forms and were generated de novo as demonstrated by their appearance and accumulation upon infection with a genetically homogeneous bacterial clone of SeMNPV (bacmid). Sequences were identified at the junctions of the non-hr ori units within the concatemers, which may be potentially involved in recombination events. Deletion of the SeMNPV non-hr ori using RecE/RecT-mediated homologous ET recombination in Escherichia coli resulted in a recombinant bacmid with strongly enhanced stability of virus and polyhedron production upon serial passage in insect cells. This suggests that the accumulation of non-hr oris upon passage is due to the replication advantage of these sequences. The non-hr ori deletion mutant SeMNPV bacmid can be exploited as a stable eukaryotic heterologous protein expression vector in insect cells. 相似文献
67.
Acidification of organelles of the eukaryotic vacuolar system is important for multiple intracellular processes including receptor-mediated endocytosis, proteolytic activity in lysosomes, and prohormone sorting and processing in secretory granules. Responsible for the generation of a proton gradient across a membrane is vacuolar H(+)-ATPase (V-ATPase). How the activity of this multisubunit enzyme is regulated remains to be established. Accessory subunits of the V-ATPase may be involved in the organelle-specific regulation, one candidate being the chromaffin granular V-ATPase-associated protein Ac45. To assess the function of Ac45, we disrupted its gene by gene targeting in male mouse embryonic stem cells. We have successfully generated Ac45 null mutant (-IY) embryonic stem cells and injected them into C57BL/6 recipient blastocysts. The blastocysts were replaced into pseudopregnant foster mothers, giving rise to 16 littermates. One of these appeared to be a low-chimeric female mouse that died 6 weeks after birth. No signs of late abortion were detected in the foster mothers. The results suggest that the injected Ac45 null mutant embryonic stem cells affect the normal development of the blastocyst and are in line with knockout studies on other V-ATPase subunits that point to an essential role for the V-ATPase in early embryonic development. 相似文献
68.
Controls on methane production in a tidal freshwater estuary and a peatland: methane production via acetate fermentation and CO2 reduction 总被引:2,自引:0,他引:2
G. Brooks Avery Robert D. Shannon Jeffrey R. White Christopher S. Martens Marc J. Alperin 《Biogeochemistry》2003,62(1):19-37
Rates of total methane production, acetate fermentation andCO2 reduction were compared for two different wetland sites. On aper-liter basis, sediments from the White Oak River estuary, a tidal freshwatersite in eastern North Carolina, had an annual methane production rate (53.3mMyr–1) an order of magnitude higher thanthat ofBuck Hollow Bog (5.5 mMyr–1), a peatlandinMichigan. Methane was produced in the White Oak River site on an annual basisbyboth acetate fermentation (72%) and CO2 reduction (28%) in a ratiotypical of freshwater methanogenic sites. Competition for acetate bynon-methanogenic microorganisms in Buck Hollow peat limited methane productionfrom acetate to only a few months a year, severely impacting annual methaneproduction rates. However, when acetate was available to the methanogens in thepeat during early spring, the percentage of methane production from acetatefermentation (84%) and CO2 reduction (16%) and rates of totalmethaneproduction were similar to those of the White Oak River sediments at the sametemperature. Rates of CO2 reduction and acetate fermentationconducted at both sites at various temperatures showed that Buck Hollow peatmethane production was also limited by a colder temperature regime as well asdifferences in the response of the CO2 reducing and aceticlasticmethanogens to temperature variations. 相似文献
69.
Schweigel M Martens H 《American journal of physiology. Gastrointestinal and liver physiology》2003,285(1):G45-G53
The K+-insensitive component of Mg2+ influx in primary culture of ruminal epithelial cells (REC) was examined by means of fluorescence techniques. The effects of extracellular anions, ruminal fermentation products, and transport inhibitors on the intracellular free Mg2+ concentration ([Mg2+]i), Mg2+ uptake, and intracellular pH were determined. Under control conditions (HEPES-buffered high-NaCl medium), the [Mg2+]i of REC increased from 0.56 +/- 0.14 to 0.76 +/- 0.06 mM, corresponding to a Mg2+ uptake rate of 15 microM/min. Exposure to butyrate did not affect Mg2+ uptake, but it was stimulated (by 84 +/- 19%) in the presence of CO2/HCO(-)3. In contrast, Mg2+ uptake was strongly diminished if REC were suspended in HCO(-)3-buffered high-KCl medium (22.3 +/- 4 microM/min) rather than in HEPES-buffered KCl medium (37.5 +/- 6 microM/min). After switching from high- to low-Cl- solution, [Mg2+]i was reduced from 0.64 +/- 0.09 to 0.32 +/- 0.16 mM and the CO2/HCO(-)3-stimulated Mg2+ uptake was completely inhibited. Bumetanide and furosemide blocked the rate of Mg2+ uptake by 64 and 40%, respectively. Specific blockers of vacuolar H+-ATPase reduced the [Mg2+]i (36%) and Mg2+ influx (38%) into REC. We interpret this data to mean that the K+-insensitive Mg2+ influx into REC is mediated by a cotransport of Mg2+ and Cl- and is energized by an H+-ATPase. The stimulation of Mg2+ transport by ruminal fermentation products may result from a modulation of the H+-ATPase activity. 相似文献
70.