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121.
Secondary ion mass spectrometry (SIMS) microscopy, a mass spectrometry method designed in the 1960s, offers new analytical capabilities, high sensitivity (ppm to ppb region), high specificity and improved lateral resolution, thus facilitating insight into many physiological and biomedical questions. Apart from the sample preparation and the physical characteristics of the detection, the biological model must also be considered. SIMS analysis of diffusible ions and molecules requires strict cryogenic procedures which always begin by a flash-freeze fixation. Cellular integrity can be checked by mapping the major element distributions since intra and extracellular ions are redistributed only in damaged cells. Cryofixing may be followed either by a freeze-fracture methodology or by cryoembedding and dry-cutting. Chemical sample preparation is only used for ions or molecules bound to fixed cell structures. The use of scanning procedures ameliorates the lateral resolution and chromosome imaging has been reported with probe size of below 50nm. Absolute quantification can be derived for embedded specimen by using internal references included in tissue equivalent resins. The sensitivity is limited by the ionization yield of the tag element and may be further impaired when working at high mass resolution (≥5000) to eliminate interfering cluster ions. SIMS drug mapping is usually performed after in vitro administration of a molecule to cell culture systems. Drug detection is accomplished indirectly by detecting a tag isotope naturally present or introduced by labelling, mainly with halogens,15N and14C. Molecular imaging with TOF-SIMS is an appealing alternative especially for heavier compounds. We stress some biological problems through a critical review of published SIMS drug studies. SIMS proved useful in assessing the targeting specificity of nuclear medicine pharmaceutics, even after in vivo administration. The first microscopic evidence of a thionamide induced follicular blockade of the iodine organification process is presented in a human sample. 相似文献
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1. Antlions are opportunistic trap building predators that cannot control prey encounter. Their trap should ideally retain a great diversity of prey. However, building a single trap that captures many prey with varying characteristics can be challenging. 2. A series of five different ant species ranging from thin to large, of sizes ranging from 2.75 to 6.5 mm, and a mean weight ranging from 0.54 to 6.00 mg were offered in a random succession to antlions. The state of satiation of the antlions was controlled, and their mass and the depth of their pit were recorded. The reaction of antlion to the prey, the probability of capture as well as the time to escape were recorded. 3. The probability of an antlion reaction is an increasing function of the pit depth and a decreasing function of antlion mass. The probability of capture is highest for intermediate prey mass and is an increasing function of pit depth. The time to escape is a declining function of prey mass and an increasing function of pit depth. 4. There is an upper limit to prey mass given that large prey escape out of the pit. There is a lower limit to prey mass given the difficulty to apprehend the smallest, thin species. Consequently, there is a range of prey mass, corresponding to a medium‐sized ant of 2 mg, for which the pit functions best. The physics of insect locomotion on sandy slopes was identified as the key to understanding the functioning of antlion pits. 相似文献
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M E Eremeeva V F Ignatovich V L Popov N M Balaeva 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1989,(7):12-17
The methods used for the sparing inactivation of highly concentrated R. prowazekii biomass and for the decrease of its infectious activity are described. These methods are recommended for use in experiments in the field of molecular biology, as well as for disinfection of different materials contaminated with rickettsiae. As conditions for complete inactivation, incubation at 50 degrees C for 1 hour without chemical disinfectants, treatment with 0.5% phenol solution at 30 degrees C for 12 hours and with 0.1% formaldehyde solution at 4 degrees C for 24 hours have been selected. Treatment with 0.5% phenol solution at 36 degrees C for 1 hour or incubation at 45 degrees C without the use of disinfectants ensures an essential decrease in the infectivity of the material if the work with viable infective agents is necessary. Ultraviolet irradiation for 1.5 hours and exposure to the action of 0.1-0.5% sodium azide are less effective. 相似文献
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Morphometric variation in Ground Beetle Carabus aeruginosus F.-W. was studied. Beetles were sampled in different habitats in the gradient of disturbance: Kemerovo city, its suburbs and natural biotopes outside the city. We used multidimensional statistics (linear models, PCA and MDS) to show that all environmental factors (anthropogenic press, biotope vegetation) contributed significantly into the beetles body size variation. Various responses of males and females to the environmental factors led to the sexual size dimorphism. The value of the latter was the highest in the meadows and the lowest in urban habitats. Sexual shape dimorphism was recorded in Carabus aeruginosus also. 相似文献
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GUOWEI LI MARIE BOUDSOCQ SONIA HEM JÉRÔME VIALARET MICHEL ROSSIGNOL CHRISTOPHE MAUREL VÉRONIQUE SANTONI 《Plant, cell & environment》2015,38(7):1312-1320
The hydraulic conductivity of plant roots (Lpr) is determined in large part by the activity of aquaporins. Mechanisms occurring at the post‐translational level, in particular phosphorylation of aquaporins of the plasma membrane intrinsic protein 2 (PIP2) subfamily, are thought to be of critical importance for regulating root water transport. However, knowledge of protein kinases and phosphatases acting on aquaporin function is still scarce. In the present work, we investigated the Lpr of knockout Arabidopsis plants for four Ca2+‐dependent protein kinases. cpk7 plants showed a 30% increase in Lpr because of a higher aquaporin activity. A quantitative proteomic analysis of wild‐type and cpk7 plants revealed that PIP gene expression and PIP protein quantity were not correlated and that CPK7 has no effect on PIP2 phosphorylation. In contrast, CPK7 exerts a negative control on the cellular abundance of PIP1s, which likely accounts for the higher Lpr of cpk7. In addition, this study revealed that the cellular amount of a few additional proteins including membrane transporters is controlled by CPK7. The overall work provides evidence for CPK7‐dependent stability of specific membrane proteins. 相似文献
130.
Sathiyamoorthy Meiyalaghan Philippa J Barrell Jeanne ME Jacobs Anthony J Conner 《BMC biotechnology》2011,11(1):1-10