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21.
The ability to manipulate biological cells and micrometre-scale particles plays an important role in many biological and colloidal science applications. However, conventional manipulation techniques--including optical tweezers, electrokinetic forces (electrophoresis, dielectrophoresis, travelling-wave dielectrophoresis), magnetic tweezers, acoustic traps and hydrodynamic flows--cannot achieve high resolution and high throughput at the same time. Optical tweezers offer high resolution for trapping single particles, but have a limited manipulation area owing to tight focusing requirements; on the other hand, electrokinetic forces and other mechanisms provide high throughput, but lack the flexibility or the spatial resolution necessary for controlling individual cells. Here we present an optical image-driven dielectrophoresis technique that permits high-resolution patterning of electric fields on a photoconductive surface for manipulating single particles. It requires 100,000 times less optical intensity than optical tweezers. Using an incoherent light source (a light-emitting diode or a halogen lamp) and a digital micromirror spatial light modulator, we have demonstrated parallel manipulation of 15,000 particle traps on a 1.3 x 1.0 mm2 area. With direct optical imaging control, multiple manipulation functions are combined to achieve complex, multi-step manipulation protocols. 相似文献
22.
Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors 总被引:4,自引:0,他引:4
Transparent electronic devices formed on flexible substrates are expected to meet emerging technological demands where silicon-based electronics cannot provide a solution. Examples of active flexible applications include paper displays and wearable computers. So far, mainly flexible devices based on hydrogenated amorphous silicon (a-Si:H) and organic semiconductors have been investigated. However, the performance of these devices has been insufficient for use as transistors in practical computers and current-driven organic light-emitting diode displays. Fabricating high-performance devices is challenging, owing to a trade-off between processing temperature and device performance. Here, we propose to solve this problem by using a novel semiconducting material--namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)--for the active channel in transparent thin-film transistors (TTFTs). The a-IGZO is deposited on polyethylene terephthalate at room temperature and exhibits Hall effect mobilities exceeding 10 cm2 V(-1) s(-1), which is an order of magnitude larger than for hydrogenated amorphous silicon. TTFTs fabricated on polyethylene terephthalate sheets exhibit saturation mobilities of 6-9 cm2 V(-1) s(-1), and device characteristics are stable during repetitive bending of the TTFT sheet. 相似文献
23.
In vitro effects on microtubule dynamics of purified Xenopus M phase-activated MAP kinase. 总被引:49,自引:0,他引:49
Y Gotoh E Nishida S Matsuda N Shiina H Kosako K Shiokawa T Akiyama K Ohta H Sakai 《Nature》1991,349(6306):251-254
The protein kinase MAP kinase, also called MAP2 kinase, is a serine/threonine kinase whose activation and phosphorylation are induced by a variety of mitogens, and which is thought to have a critical role in a network of protein kinases in mitogenic signal transduction. A burst in kinase activation and protein phosphorylation may also be important in triggering the dramatic reorganization of the cell during the transition from interphase to mitosis. The interphase-metaphase transition of microtubule arrays is under the control of p34cdc2 kinase, a central control element in the G2-M transition of the cell cycle. Here we show that a Xenopus kinase, closely related to the mitogen-activated mammalian MAP kinase, is phosphorylated and activated during M phase of meiotic and mitotic cell cycles, and that the interphase-metaphase transition of microtubule arrays can be induced by the addition of purified Xenopus M phase-activated MAP kinase or mammalian mitogen-activated MAP kinase to interphase extracts in vitro. 相似文献
24.
25.
A non‐linear dynamic model is introduced for multiplicative seasonal time series that follows and extends the X‐11 paradigm where the observed time series is a product of trend, seasonal and irregular factors. A selection of standard seasonal and trend component models used in additive dynamic time series models are adapted for the multiplicative framework and a non‐linear filtering procedure is proposed. The results are illustrated and compared to X‐11 and log‐additive models using real data. In particular it is shown that the new procedures do not suffer from the trend bias present in log‐additive models. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
26.
Y Ohta 《Experientia》1984,40(5):505-506
Enhancement of decidual cell reaction (DCR) following adrenalectomy was reversed by corticosterone as well as indomethacin. The results suggest the adrenal involvement in DCR through uterine prostaglandin production. 相似文献
27.
In female rats given a single injection of 1.25 mg 5 alpha-dihydrotestosterone during neonatal life, reactivity of the vaginal mucosa to hormones was permanently altered, so that the rats, when adult, could show vaginal cornification under the hormonic conditions supportive of development of deciduomata in the uterus. 相似文献
28.
29.
DMY is a Y-specific DM-domain gene required for male development in the medaka fish 总被引:46,自引:0,他引:46
Matsuda M Nagahama Y Shinomiya A Sato T Matsuda C Kobayashi T Morrey CE Shibata N Asakawa S Shimizu N Hori H Hamaguchi S Sakaizumi M 《Nature》2002,417(6888):559-563
Although the sex-determining gene Sry has been identified in mammals, no comparable genes have been found in non-mammalian vertebrates. Here, we used recombinant breakpoint analysis to restrict the sex-determining region in medaka fish (Oryzias latipes) to a 530-kilobase (kb) stretch of the Y chromosome. Deletion analysis of the Y chromosome of a congenic XY female further shortened the region to 250 kb. Shotgun sequencing of this region predicted 27 genes. Three of these genes were expressed during sexual differentiation. However, only the DM-related PG17 was Y specific; we thus named it DMY. Two naturally occurring mutations establish DMY's critical role in male development. The first heritable mutant--a single insertion in exon 3 and the subsequent truncation of DMY--resulted in all XY female offspring. Similarly, the second XY mutant female showed reduced DMY expression with a high proportion of XY female offspring. During normal development, DMY is expressed only in somatic cells of XY gonads. These findings strongly suggest that the sex-specific DMY is required for testicular development and is a prime candidate for the medaka sex-determining gene. 相似文献
30.
Katsunori Nakamura Mamoru Takehana Tsuneo Itagaki Hayato Tashiro Kazumasa Ohta Osamu Nakakita 《南京林业大学学报(自然科学版)》2011,(4):150-151
有效监测患病株方法的缺失是导致对松萎蔫病难以成功控制的主要原因之一。利用航空手段调查该病导致的针叶颜色变化已被证明是一种可靠的方法。为了克服该方法固有的缺点,笔者引用了近红外彩色胶片航拍方法。该项技术在获得正摄航拍图像时,通过图像处理可以增强松针颜色变化,获得较直接拍摄图像更明显的色差。因为图像可以在室内仔细处理,因此能解决飞行时间缺乏等问题。但是,该方法也存在对被压木无法获得其影像而漏检的缺陷。笔者研发的计算机软件可以将目标树标记在计算机图像文件上,并且标记树的地理位置数据和背景航拍图像并传输到装有内置GPS接收器的掌上电脑中,借助软件产生的图像导航定位系统,有利于地面接近标记树,从而可以现场检查和校正标记树的数据,并将修正数据传回至主机。此方法利用最新航拍图像技术建立对每株树处理和管理的连续资料,大大改善了防控松萎蔫病的措施。 相似文献