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21.
Roderick I. Mackie Satoshi Koike Ivan Krapac Joanne Chee-Sanford Scott Maxwell Rustam I. Aminov 《Animal biotechnology》2013,24(2):157-176
Antibiotics are used at therapeutic levels to treat disease; at slightly lower levels as prophylactics; and at low, subtherapeutic levels for growth promotion and improvement of feed efficiency. Over 88% of swine producers in the United States gave antimicrobials to grower/finisher pigs in feed as a growth promoter in 2000. It is estimated that ca. 75% of antibiotics are not absorbed by animals and are excreted in urine and feces. The extensive use of antibiotics in swine production has resulted in antibiotic resistance in many intestinal bacteria, which are also excreted in swine feces, resulting in dissemination of resistance genes into the environment. To assess the impact of manure management on groundwater quality, groundwater samples have been collected near two swine confinement facilities that use lagoons for manure storage and treatment. Several key contaminant indicators—including inorganic ions, antibiotics, and antibiotic resistance genes—were analyzed in groundwater collected from the monitoring wells. Chloride, ammonium, potassium, and sodium were predominant inorganic constituents in the manure samples and served as indicators of groundwater contamination. Based on these analyses, shallow groundwater has been impacted by lagoon seepage at both sites. Liquid chromatography-mass spectroscopy (LC-MS) was used to measure the dissolved concentrations of tetracycline, chlortetracycline, and oxytetracycline in groundwater and manure. Although tetracyclines were regularly used at both facilities, they were infrequently detected in manure samples and then at relatively trace concentrations. Concentrations of all tetracyclines and their breakdown products in the groundwater sampled were generally less than 0.5 μg/L. Bacterial tetracycline resistance genes served as distinct genotypic markers to indicate the dissemination and mobility of antibiotic resistance genes that originated from the lagoons. Applying PCR to genomic DNA extracted from the lagoon and groundwater samples, four commonly occurring tetracycline (tet) resistance genes—tet(M), tet(O), tet(Q), and tet(W)—were detected. The detection frequency of tet genes was much higher in wells located closer to and down-gradient from the lagoons than in wells more distant from the lagoons. These results suggested that in the groundwater underlying both facilities tetracycline resistance genes exist and are somewhat persistent, but that the distribution and potentially the flux for each tet gene varied throughout the study period. 相似文献
22.
G. O. Mackie 《Marine and Freshwater Behaviour and Physiology》2013,45(4):325-346
Intracellular and extracellular recordings from the stem, gastrozooids, palpons, tentacles and nectophores of physonectid siphonophores are presented. The stem organization previously described for Nanomia applies with only minor differences to Forskalia and Agalma. The endodermal epithelium of the stem is shown to be the pathway for slow potentials. Pumping cycles and feeding activities are organized locally in gastrozooids and palpons. Protective retractions are coordinated, probably through a direct nervous link with the stem. This is also true of tentacles. The ectoderm of bracts is a conducting epithelium; excitation in it can induce nervous activity in the stem, but the mechanism is unknown. Impulse traffic between stem and zooids is erratic and breaks down rapidly with repeated stimulation. The motor centres of the nectophores are connected to the stem by a labile nervous link, but an alternative epithelial pathway exists. 相似文献
23.
G. O. Mackie 《Marine and Freshwater Behaviour and Physiology》2013,45(2-4):197-205
The zooids in colonial tunicates do not appear to be directly interconnected by nerves, but this has not prevented the evolution of coordinated behaviour in several groups. In Botryllus and other colonial styelid asci‐dians the endothelium lining the blood vessels is excitable and transmits action potentials from cell to cell via gap junctions. These signals mediate protective contractions of the zooids and synchronize contractions of the vascular ampullae. In didemnid ascidians such as Diplosoma a network of myocytes in the tunic serves to transmit excitation and to cause contractions of the cloacal apertures. Individual zooids of Pyrosoma protect themselves by closing their siphons and arresting their branchial cilia when stimulated. At the same time a flash of light is emitted. Neighbouring zooids sense the flash with their photoreceptors and respond in turn with protective responses and light emission. Protective responses thus spread by photic signalling and propagate from zooid to zooid through the colony in a saltatory manner. In chains of Salpafusifortnis, changes in the direction and/or speed of swimming are transmitted from zooid to zooid via adhesion plaques. When a zooid is stimulated, its body‐wall epithelium conducts action potentials to the plaque connecting it to the next zooid, exciting receptor neurons in that zooid. These receptors have sensory processes that bridge the gap between the two zooids. The sensory neurons so excited in the second zooid conduct impulses to the brain where they alter the motor output pattern, and at the same time generate epithelial action potentials that travel to the next zooid in line, where the same thing happens. It is not clear why these unconventional signalling methods have evolved but the tunic may be an inhospitable environment for nerves, making conventional nervous links impossible. 相似文献
24.
Alexander R. Mackie Prasanna Krishnamurthy Suresh K. Verma Tina Thorne Veronica Ramirez Gangjian Qin Tatiana Abramova Hiromichi Hamada Douglas W. Losordo Raj Kishore 《The Journal of biological chemistry》2013,288(25):18022-18034
We have shown previously that estrogen (estradiol, E2) supplementation enhances voluntary alcohol consumption in ovariectomized female rodents and that increased alcohol consumption impairs ischemic hind limb vascular repair. However, the effect of E2-induced alcohol consumption on post-infarct myocardial repair and on the phenotypic/functional properties of endothelial progenitor cells (EPCs) is not known. Additionally, the molecular signaling of alcohol-estrogen interactions remains to be elucidated. This study examined the effect of E2-induced increases in ethanol consumption on post-infarct myocardial function/repair. Ovariectomized female mice, implanted with 17β-E2 or placebo pellets were given access to alcohol for 6 weeks and subjected to acute myocardial infarction. Left ventricular functions were consistently depressed in mice consuming ethanol compared with those receiving only E2. Alcohol-consuming mice also displayed significantly increased infarct size and reduced capillary density. Ethanol consumption also reduced E2-induced mobilization and homing of EPCs to injured myocardium compared with the E2-alone group. In vitro, exposure of EPCs to ethanol suppressed E2-induced proliferation, survival, and migration and markedly altered E2-induced estrogen receptor-dependent cell survival signaling and gene expression. Furthermore, ethanol-mediated suppression of EPC biology was endothelial nitric oxide synthase-dependent because endothelial nitric oxide synthase-null mice displayed an exaggerated response to post-acute myocardial infarction left ventricular functions. These data suggest that E2 modulation of alcohol consumption, and the ensuing EPC dysfunction, may negatively compete with the beneficial effects of estrogen on post-infarct myocardial repair. 相似文献
25.
Fu J Astarita G Gaetani S Kim J Cravatt BF Mackie K Piomelli D 《The Journal of biological chemistry》2007,282(2):1518-1528
Oleoylethanolamide (OEA) is a lipid mediator that inhibits food intake by activating the nuclear receptor peroxisome proliferator-activated receptor-alpha. In the rodent small intestine OEA levels decrease during food deprivation and increase upon refeeding, suggesting that endogenous OEA may participate in the regulation of satiety. Here we show that feeding stimulates OEA mobilization in the mucosal layer of rat duodenum and jejunum but not in the serosal layer from the same intestinal segments in other sections of the gastrointestinal tract (stomach, ileum, colon) or in a broad series of internal organs and tissues (e.g. liver, brain, heart, plasma). Feeding also increases the levels of other unsaturated fatty acid ethanolamides (FAEs) (e.g. linoleoylethanolamide) without affecting those of saturated FAEs (e.g. palmitoylethanolamide). Feeding-induced OEA mobilization is accompanied by enhanced accumulation of OEA-generating N-acylphosphatidylethanolamines (NAPEs) increased activity and expression of the OEA-synthesizing enzyme NAPE-phospholipase D, and decreased activity and expression of the OEAdegrading enzyme fatty acid amide hydrolase. Immunostaining studies revealed that NAPE-phospholipase D and fatty acid amide hydrolase are expressed in intestinal enterocytes and lamina propria cells. Collectively, these results indicate that nutrient availability controls OEA mobilization in the mucosa of the proximal intestine through a concerted regulation of OEA biosynthesis and degradation. 相似文献
26.
Brooks PJ Wise DS Berry DA Kosmoski JV Smerdon MJ Somers RL Mackie H Spoonde AY Ackerman EJ Coleman K Tarone RE Robbins JH 《The Journal of biological chemistry》2000,275(29):22355-22362
Xeroderma pigmentosum (XP) patients with inherited defects in nucleotide excision repair (NER) are unable to excise from their DNA bulky photoproducts induced by UV radiation and therefore develop accelerated actinic damage, including cancer, on sun-exposed tissue. Some XP patients also develop a characteristic neurodegeneration believed to result from their inability to repair neuronal DNA damaged by endogenous metabolites since the harmful UV radiation in sunlight does not reach neurons. Free radicals, which are abundant in neurons, induce DNA lesions that, if unrepaired, might cause the XP neurodegeneration. Searching for such a lesion, we developed a synthesis for 8,5'-(S)-cyclo-2'-deoxyadenosine (cyclo-dA), a free radical-induced bulky lesion, and incorporated it into DNA to test its repair in mammalian cell extracts and living cells. Using extracts of normal and mutant Chinese hamster ovary (CHO) cells to test for NER and adult rat brain extracts to test for base excision repair, we found that cyclo-dA is repaired by NER and not by base excision repair. We measured host cell reactivation, which reflects a cell's capacity for NER, by transfecting CHO and XP cells with DNA constructs containing a single cyclo-dA or a cyclobutane thymine dimer at a specific site on the transcribed strand of a luciferase reporter gene. We found that, like the cyclobutane thymine dimer, cyclo-dA is a strong block to gene expression in CHO and human cells. Cyclo-dA was repaired extremely poorly in NER-deficient CHO cells and in cells from patients in XP complementation group A with neurodegeneration. Based on these findings, we propose that cyclo-dA is a candidate for an endogenous DNA lesion that might contribute to neurodegeneration in XP. 相似文献
27.
Preferential cleavage of degradative intermediates of rpsT mRNA by the Escherichia coli RNA degradosome 下载免费PDF全文
RNase E, the principal RNase capable of initiating mRNA decay, preferentially attacks 5'-monophosphorylated over 5'-triphosphorylated substrates. Site-specific cleavage in vitro of the rpsT mRNA by RNase H directed by chimeric 2'-O-methyl oligonucleotides was employed to create truncated RNAs which are identical to authentic degradative intermediates. The rates of cleavage of two such intermediates by RNase E in the RNA degradosome are significantly faster (2.5- to 8-fold) than that of intact RNA. This verifies the preference of RNase E for degradative intermediates and can explain the frequent "all-or-none" behavior of mRNAs during the decay process. 相似文献
28.
3-Phenylpropanoic Acid Improves the Affinity of Ruminococcus albus for Cellulose in Continuous Culture 下载免费PDF全文
A continuous-culture device, adapted for use with solid substrates, was used to evaluate the effects of 3-phenylpropanoic acid (PPA) upon the ability of the South African strain Ruminococcus albus Ce63 to ferment cellulose. Steady states of fermentation were established with a dilution rate of 0.17 h−1, and the extent and volumetric rates of cellulose fermentation were determined over four consecutive days. When the growth medium contained no additions (control), 25 μM phenylacetate alone, 25 μM PPA alone, or 25 μM each of phenylacetate and PPA, the extent of cellulose hydrolysis was determined to be 41.1, 35.7, 90.2, and 86.9%, respectively, and the volumetric rate of cellulose hydrolysis was 103.0, 97.9, 215.5, and 230.4 mg liter−1 h−1, respectively. To evaluate the effect of PPA availability on affinity for cellulose, the values for dilution rate and extent of cellulose hydrolysis were used in combination with values for maximum specific growth rate determined from previous studies of growth rates and kinetics of cellulose hydrolysis. The findings support the contention that PPA maintains a competitive advantage for R. albus when grown in a dynamic, fiber-rich environment. 相似文献
29.
A pBR322 plasmid which contains a fragment of Escherichia coli DNA encoding the lipoprotein signal peptidase gene was used to transform Hfr polA1 strains. Ampr transformants were used as donors in conjugation experiments, and the location of the plasmid amp gene adjacent to the chromosomal lsp gene was determined to be near the thr ara loci of the E. coli chromosome. P1 transduction experiments established that the location of the lsp gene is closely linked to that of dapB , at 0.5 to 0.6 min on the E. coli genetic map. The position of the lsp gene was further determined to be between ileS and dapB by complementation analysis of an E. coli mutant showing temperature-sensitive prolipoprotein signal peptidase activity. 相似文献
30.
Behavioral phenotypes of Disc1 missense mutations in mice 总被引:6,自引:0,他引:6
Clapcote SJ Lipina TV Millar JK Mackie S Christie S Ogawa F Lerch JP Trimble K Uchiyama M Sakuraba Y Kaneda H Shiroishi T Houslay MD Henkelman RM Sled JG Gondo Y Porteous DJ Roder JC 《Neuron》2007,54(3):387-402
To support the role of DISC1 in human psychiatric disorders, we identified and analyzed two independently derived ENU-induced mutations in Exon 2 of mouse Disc1. Mice with mutation Q31L showed depressive-like behavior with deficits in the forced swim test and other measures that were reversed by the antidepressant bupropion, but not by rolipram, a phosphodiesterase-4 (PDE4) inhibitor. In contrast, L100P mutant mice exhibited schizophrenic-like behavior, with profound deficits in prepulse inhibition and latent inhibition that were reversed by antipsychotic treatment. Both mutant DISC1 proteins exhibited reduced binding to the known DISC1 binding partner PDE4B. Q31L mutants had lower PDE4B activity, consistent with their resistance to rolipram, suggesting decreased PDE4 activity as a contributory factor in depression. This study demonstrates that Disc1 missense mutations in mice give rise to phenotypes related to depression and schizophrenia, thus supporting the role of DISC1 in major mental illness. 相似文献