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281.
Molecular Biology Reports - CYP24A1 plays a role in strictly regulated vitamin D metabolism pathway and has been nominated as a prognostic biomarker for colorectal cancer (CRC). Increasing evidence...  相似文献   
282.
117 antigen is involved in the process of intercellular cohesion in Dictyostelium discoideum [Brodie et al., 1983]. The antigen, a 69- and 72-kDa doublet, was found to arise from a 60- and 62-kDa precursor. The mature antigen contains N-linked oligosaccharides that are sulfated and fucosylated [Sadeghi et al., 1987]. These oligosaccharide chains are resistant to endoglycosidase H digestion. 117 antigen also contains a post-translationally added carbohydrate-containing modification(s). Unlike the N-linked oligosaccharide, this carbohydrate moiety is sensitive to periodate oxidation. 117 antigen is developmentally regulated, and the changes in rate of 117 antigen synthesis reflect changes in the cellular levels of its mRNA. 117 mRNA accumulates in starving cells and reaches its maximum when cells become aggregation competent. The mRNA levels then decline, and by the time the slug structure is formed, no 117 mRNA is present. 117 mRNA reaccumulates for a brief period during early culmination and then returns to an undetectable level.  相似文献   
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Neural stem cell (NSC) culture is a remarkable tool to investigate the potential therapeutic benefits of drugs in neurological diseases. The purpose of this study was to determine the effect of melatonin on proliferation and differentiation of NSCs in vitro. NSCs were isolated and expanded from mouse embryonic E14 cortex, and the effect of various concentrations of melatonin (0.05, 0.1, 0.5, 1, 5 and 10 μM) on NSC proliferation was assessed by MTT and neurosphere assay. Results showed that melatonin significantly increased NSC viability and NSC proliferation in a dose-dependent manner, in comparison to controls. Similarly, neurosphere formation frequency and cell counts increased significantly with increasing melatonin concentrations and reached its peak at 0.5 μM, in comparison to controls. Moreover, NSCs treated with either low (0.05 µM) or high concentrations (5 µM) of melatonin showed that the mean percentage of glial fibrillary acidic protein (GFAP) positive cells were not significantly different in PDGF or melatonin at 5 μM, in comparison to controls. However, low melatonin concentrations (0.05 µM) showed a slight significant increase in comparison to controls and PDGF. On the other hand, both concentrations of melatonin treatment significantly increased the percentage of myelin basic protein (MBP) positive cells (oligodendrocytes), in comparison to controls and to PDGF. Our results demonstrated, for the first time, that melatonin increased oligodendrocyte differentiation from NSCs. These results suggest that melatonin might have a potential therapeutic effect for some neurological diseases that involve oligodendrocyte and myelin pathologies.  相似文献   
285.
The purpose of this study is to validate the capability of in-house independent point dose calculation software to be used as a second check for Helical Tomotherapy treatment plans. The software performed its calculations in homogenous conditions (using the Cheese phantom, which is a cylindrical phantom with radius 15 cm and length 18 cm) using a factor-based algorithm. Fifty patients, who were treated for pelvic (10), prostate (14), lung (10), head & neck (12) and brain (4) cancers, were used. Based on the individual patient kVCT images and the pretreatment MVCT images for each treatment fraction, the corresponding daily patient setup shifts in the IEC-X, IEC-Y, and IEC-Z directions were registered. For each patient, the registered fractional setup shifts were grouped into systematic and random shifts. The average systematic dosimetric variations showed small dose deviation for the different cancer types (1.0%–3.0%) compared to the planned dose. Of the fifty patients, only three had percent differences larger than 5%. The average random dosimetric variations showed relatively small dose deviations (0.2%–1.1%) compared to the planned dose. None of the patients had percent differences larger than 5%. By examining the individual fractions of each patient, it is observed that only in 31 out of 1358 fractions the percent differences exceeded the border of 5%. These results indicate that the overall dosimetric impact from systematic and random variations is small and that the software is a capable platform for independent point dose validation for the Helical Tomotherapy modality.  相似文献   
286.
The hoverfly Trichopsomyia ochrozona (Stackelberg, 1952) (Diptera: Syrphidae) is recorded for the first time from Iran. An illustrated key to the West Palaearctic species of Trichopsomyia is presented. Illustrations of the puparium of Trichopsomyia joratensis Goeldin, 1997 and the larva and puparium of T. ochrozona are given and their larval and adult habitats are described. A short discussion is given on the known larval habitat of other West Palaearctic Trichopsomyia species. Some of the synonyms have been evaluated and Pipiza melancholica Meigen, 1822 is withdrawn from synonymy of Trichopsomyia flavitarsis (Meigen, 1822) and is considered as a junior synonym of Musca viduata Linnaeus, 1758 syn. nov.  相似文献   
287.
One million, six hundred thirty-two thousand, eight hundred forty-seven women from two independent populations in the United States received cytologic screening during a two-year period. Condylomatous lesions (human papillomavirus [HPV] infections) were the most frequent cytologic abnormality in women in both the Planned Parenthood and private sector groups (prevalence rates of 18.6 to 19.0 in women between ages 15 to 19). The prevalence rates of mild-to-moderate dysplasia were also similar in both populations, with the highest frequencies being between ages 25 to 29. Severe dysplasia and carcinoma in situ were most frequent between ages 35 to 39. In both populations, women with condylomatous changes coexisting with dysplastic changes were about ten years younger, grade-for-grade of severity of the lesion, than women without evidence of HPV infection. Since HPV infection is believed to represent the soil from which neoplasm develops, both the frequency of condyloma and the occurrence of dysplasia and cancer in young women suggest that women should begin regular screening programs while in their teens or after they become sexually active.  相似文献   
288.
Hidden Markov Models (HMMs) are practical tools which provide probabilistic base for protein secondary structure prediction. In these models, usually, only the information of the left hand side of an amino acid is considered. Accordingly, these models seem to be inefficient with respect to long range correlations. In this work we discuss a Segmental Semi Markov Model (SSMM) in which the information of both sides of amino acids are considered. It is assumed and seemed reasonable that the information on both sides of an amino acid can provide a suitable tool for measuring dependencies. We consider these dependencies by dividing them into shorter dependencies. Each of these dependency models can be applied for estimating the probability of segments in structural classes. Several conditional probabilities concerning dependency of an amino acid to the residues appeared on its both sides are considered. Based on these conditional probabilities a weighted model is obtained to calculate the probability of each segment in a structure. This results in 2.27% increase in prediction accuracy in comparison with the ordinary Segmental Semi Markov Models, SSMMs. We also compare the performance of our model with that of the Segmental Semi Markov Model introduced by Schmidler et al. [C.S. Schmidler, J.S. Liu, D.L. Brutlag, Bayesian segmentation of protein secondary structure, J. Comp. Biol. 7(1/2) (2000) 233-248]. The calculations show that the overall prediction accuracy of our model is higher than the SSMM introduced by Schmidler.  相似文献   
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