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91.
The number of cattle herds placed under movement restrictions in Great Britain (GB) due to the suspected presence of bovine tuberculosis (bTB) has progressively increased over the past 25 years despite an intensive and costly test-and-slaughter control program. Around 38% of herds that clear movement restrictions experience a recurrent incident (breakdown) within 24 months, suggesting that infection may be persisting within herds. Reactivity to tuberculin, the basis of diagnostic testing, is dependent on the time from infection. Thus, testing efficiency varies between outbreaks, depending on weight of transmission and cannot be directly estimated. In this paper, we use Approximate Bayesian Computation (ABC) to parameterize two within-herd transmission models within a rigorous inferential framework. Previous within-herd models of bTB have relied on ad-hoc methods of parameterization and used a single model structure (SORI) where animals are assumed to become detectable by testing before they become infectious. We study such a conventional within-herd model of bTB and an alternative model, motivated by recent animal challenge studies, where there is no period of epidemiological latency before animals become infectious (SOR). Under both models we estimate that cattle-to-cattle transmission rates are non-linearly density dependent. The basic reproductive ratio for our conventional within-herd model, estimated for scenarios with no statutory controls, increases from 1.5 (0.26–4.9; 95% CI) in a herd of 30 cattle up to 4.9 (0.99–14.0) in a herd of 400. Under this model we estimate that 50% (33–67) of recurrent breakdowns in Britain can be attributed to infection missed by tuberculin testing. However this figure falls to 24% (11–42) of recurrent breakdowns under our alternative model. Under both models the estimated extrinsic force of infection increases with the burden of missed infection. Hence, improved herd-level testing is unlikely to reduce recurrence unless this extrinsic infectious pressure is simultaneously addressed.  相似文献   
92.
Genomic location and characterisation of MIC genes in cattle   总被引:1,自引:0,他引:1  
Major histocompatibility complex (MHC) class I chain-related (MIC) genes have been previously identified and characterised in human. They encode polymorphic class I-like molecules that are stress-inducible, and constitute one of the ligands of the activating natural killer cell receptor NKG2D. We have identified three MIC genes within the cattle genome, located close to three non-classical MHC class I genes. The genomic position relative to other genes is very similar to the arrangement reported in the pig MHC region. Analysis of MIC cDNA sequences derived from a range of cattle cell lines suggest there may be four MIC genes in total. We have investigated the presence of the genes in distinct and well-defined MHC haplotypes, and show that one gene is consistently present, while configuration of the other three genes appears variable.  相似文献   
93.
The energy density (ED; kcal/g) of an entrée influences children's energy intake (EI), but the effect of simultaneously changing both ED and portion size of an entrée on preschool children's EI is unknown. In this within-subject crossover study, 3- to 5-year-old children (30 boys, 31 girls) in a daycare facility were served a test lunch once/week for 4 weeks. The amount and type of vegetables and cheeses incorporated into the sauce of a pasta entrée were manipulated to create two versions that varied in ED by 25% (1.6 or 1.2 kcal/g). Across the weeks, each version of the entrée was served to the children in each of two portion sizes (400 or 300 g). Lunch, consumed ad libitum, also included carrots, applesauce, and milk. Decreasing ED of the entrée by 25% significantly (P<0.0001) reduced children's EI of the entrée by 25% (63.1+/-8.3 kcal) and EI at lunch by 17% (60.7+/-8.9 kcal). Increasing the proportion of vegetables in the pasta entrée increased children's vegetable intake at lunch by half of a serving of vegetables (P<0.01). Decreasing portion size of the entrée by 25% did not significantly affect children's total food intake or EI at lunch. Therefore, reducing the ED of a lunch entrée resulted in a reduction in children's EI from the entrée and from the meal in both portion size conditions. Decreasing ED by incorporating more vegetables into recipes is an effective way of reducing children's EI while increasing their vegetable intake.  相似文献   
94.
Objective: To examine behavioral characteristics associated with being lean and weight stable during adulthood. Research Methods and Procedures: Participants included 165 white married couples who were part of a larger longitudinal study. Participants’ height and weight were measured on three occasions at 2‐year intervals. Men and women were classified as being lean and weight stable (the target group) if they had a BMI < 25 at baseline and maintained their weight within 5% of baseline at 2nd and 4th year follow‐up. Individuals not fulfilling these criteria were included in the comparison group. Group differences in background characteristics including childhood weight status, BMI at each occasion, dieting history, and mental and physical health history were examined. In addition, multiple measures of dietary intake and physical activity were obtained and used to predict the likelihood of being in the target group. Results: Men (N = 22) and women (N = 36) in the target group had lower mean BMI scores at each occasion, were less overweight during childhood, were less likely to have dieted in the past year, and rated themselves as being more healthy than men and women in the comparison group. No differences were identified in mental health. Relative to the comparison group, women in the target group reported higher levels of physical activity and higher levels of physical activity among their spouses, and men in the target group reported healthier dietary patterns. Discussion: Results from this study suggest that being lean and weight stable in adulthood is linked to childhood weight status in combination with dietary and activity patterns during adulthood.  相似文献   
95.
The effect of Ca2+ on the extent and pattern of processing of pro-opiomelanocortin and an N-terminal fragment by a purified pituitary secretory vesicle, soluble aspartic endoprotease, was studied. Ca2+ stimulated the first cleavage of pro-opiomelanocortin by pro-opiomelanocortin-converting enzyme to yield 21-23 kDa adrenocorticotropin and beta-lipotropin, but its effect was minimal. The production of adrenocorticotropin from the 21-23 kDa intermediate was stimulated approximately 2.3-fold in the presence of 10 mM Ca2+, and processing of beta-lipotropin to beta-endorphin was stimulated about 1.3-1.4-fold by 5-10 mM Ca2+. The production of gamma-melanotropin-immunoreactive material from bovine N-pro-opiomelanocortin(1-77) was stimulated approximately 1.3-fold at both 100 microM and 1.5-2.0 mM Ca2+. Further characterization of the gamma-melanotropin-immunoreactive material by HPLC demonstrated that the major products were gamma 3-[Lys]melanotropin and gamma 3-melanotropin at both Ca2+ concentrations. These results indicate that pro-opiomelanocortin-converting enzyme is stimulated by Ca2+.  相似文献   
96.
The effect of L-phenylisopropyladenosine (L-PIA), the A1 adenosine agonist, on the depth of anesthesia was investigated in halothane-anesthetized rats. L-PIA treatment reduced the minimum anesthetic concentration (MAC) of halothane that prevented 50% of animals from moving in response to a painful stimulus by 49%. MAC experiments performed with L-PIA given in conjunction with A1 adenosine receptor antagonists which either permeate the blood-brain barrier (8-phenyltheophylline [8-PT] or do not (8-sulphophenyltheophylline [8-So-PT]) indicate that central mechanisms are involved. Noradrenergic neurotransmission was diminished following L-PIA administration in halothane-anesthetized rats in all brain regions. These data suggest that acute L-PIA treatment decreases central noradrenergic neurotransmission and may represent the mechanism for the decrease in halothane dose to achieve an anesthetic endpoint anesthetic response to halothane.  相似文献   
97.
98.
An antiserum to a synthetic peptide corresponding to residues 95-117 of bovine proenkephalin recognizes all the major intermediates of this prohormone in bovine adrenal medulla (Birch, N. P. and Christie, D. L. (1986) J. Biol. Chem. 261, 12213-12221). This antiserum enabled an investigation of the stability and molecular properties of intermediates in the processing of proenkephalin in bovine adrenal medullary chromaffin granules. Intact and hypotonic lysates of chromaffin granules were incubated at 37 degrees C and the stability of intermediates assessed by gel filtration followed by radioimmunoassay and gel electrophoresis in combination with immunoblotting. Processing was slow in intact granules compared with incubations of hypotonic lysates which resulted in the selective cleavage of an Mr 27,000 intermediate and increases in the amounts of immunoreactivity of lower molecular weight. Protease inhibitors increased the stability of the 27-kilodalton intermediate, the most effective being p-chloromercuribenzoate. Preliminary evidence was obtained for the regulation of the processing of this intermediate by soluble factors present in chromaffin granules. It appears that membrane-associated intermediates of proenkephalin are relatively stable, although analysis of soluble immunoreactivity released during the incubation of chromaffin granule membranes showed a decrease in the 27-kilodalton intermediate and increased amounts of lower molecular weight intermediates. Analysis of hypotonic lysates by two-dimensional gel-electrophoresis showed that proenkephalin intermediates exhibit significant microheterogeneity. It will be important to compare the products of proenkephalin generated by purified proteases with a putative role in the processing of this prohormone with the properties of endogenous intermediates as revealed in this study.  相似文献   
99.
Best5: a novel interferon-inducible gene expressed during bone formation.   总被引:3,自引:0,他引:3  
Regulation of bone formation is important in the pathogenesis of many conditions such as osteoporosis, fracture healing, and loosening of orthopedic implants. We have recently identified a novel rat cDNA (best5) by differential display PCR that is regulated during osteoblast differentiation and bone formation in vitro and in vivo. Expression of best5 mRNA is induced in cultures of osteoblasts by both interferon-alpha (IFN-alpha) or IFN-gamma. Whereas IFN-alpha induced a rapid, transient induction of best5 expression peaking at 4-6 h poststimulation, IFN-gamma elicited a more prolonged induction of best5 expression, which remained elevated 48 h poststimulation. A polyclonal antibody generated to a peptide derived from the best5 coding region recognized a 27 kDa protein on Western blot analysis of osteoblast lysates. We localized BEST5 protein in osteoblast progenitor cells and mature osteoblasts in sections of rat tibiae and in sections of bones loaded in vivo to induce adaptive bone formation. Best5 may therefore be a fundamental intermediate in the response of osteoblasts to stimuli that modulate proliferation/differentiation, such as interferons or mechanical loading. These findings highlight the close interactions between the immune system and bone cells and may open new therapeutic avenues in modulating bone mass.  相似文献   
100.
The ability of bovine intermediate lobe secretory vesicle membrane-associated enzyme(s) and purified, soluble paired basic residue-specific, pro-opiomelanocortin converting enzyme (Loh, Y.P., Parish, D. C., and Tuteja, R. (1985) J. Biol. Chem. 260, 7194-7205) to cleave bovine NH2-terminal pro-opiomelanocortin1-77 (N-POMC 1-77) was investigated. Purified pro-opiomelanocortin converting enzyme and an enzyme activity associated with the secretory vesicle membrane were shown to cleave bovine N-POMC1-77 to two major products: N-POMC1-49 and Lys-gamma 3-melanotropin (MSH), and one minor product, gamma 3-MSH. These products were identified by their retention times on high performance liquid chromatography, immunological characteristics, and for Lys-gamma 3-MSH, amino acid composition. The products generated indicate cleavage preferentially between Arg 49-Lys 50 of bN-POMC1-77 (where b indicates bovine), which is identical to the processing pattern found in the bovine intermediate lobe in situ. The membrane converting activity was shown to be stimulated by 5 mM Ca2+ and has a pH optimum of 4-5 and an inhibitor profile characteristic of an aspartic protease. This suggests that the membrane-associated enzyme involved is very similar or identical to the purified, soluble pro-opiomelanocortin converting enzyme, which has previously been reported to be an acidic, aspartic protease responsible for the initial steps of POMC processing. The results of this study lead to the proposal that the lack of processing of the Arg49-Lys50 site in POMC in the anterior lobe versus the intermediate lobe of the pituitary in vivo may be due to other regulatory mechanisms rather than invoking the existence in the intermediate lobe of another enzyme specific for this site, different from pro-opiomelanocortin converting enzyme.  相似文献   
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