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The theory of spectral invariants, or ‘p-theory’, states that the canopy scattering coefficient at any wavelength can be related to the leaf scattering coefficient at the same wavelength through a spectrally invariant canopy structural parameter — the photon recollision probability p. The p-theory has recently gained interest in the vegetation reflectance modeling community as an efficient tool for characterizing scattering in clumped foliage structures. In this short communication paper, we report empirical data of the relationship of canopy leaf area index (LAI), diffuse non-interceptance and photon recollision probability for 1032 coniferous and broadleaved forest plots measured in Finland. Our results indicate that the relationship of canopy LAI and diffuse non-interceptance is near-universal in boreal stands i.e. it does not depend on stand age, tree species or growth conditions. This allows improving parameterizations used by canopy reflectance models which utilize the photon recollision probability concept. Our results also suggest that establishing species-specific p-LAI functions for northern European forests requires more research on the influence of micro- and macroscale foliage grouping on photon recollision probability.  相似文献   
3.
Linux, is an Unix-like operating system. Although it is used mainly as a server operating system, it is slowly gaining more acceptance amongst end users. It has integrated security features and has the potential to help users protect themselves against malware. However, as we have seen, even Linux is not immune from such attacks.While the number of Windows worms has been increasing exponentially, to date there have only been a handful of malware programs directed at Linux. But as the number of workstation users running Linux increases, and as home users start to be connected via leased lines to the Internet, the situation may change. One indication of such progress was seen earlier this year, when Ramen was spreading Linux systems.This paper concentrates on current Linux malware, and describes the most typical malware seen on a Linux host.

Worms

The first Linux worm found in the wild, namely ADMworm, was reported by CERT®/CC[1] in 1998. It propagated in a fully automated fashion using a buffer overflow vulnerability in bind Domain Name Service server [1], and as such was very similar to the Internet Worm created by Robert Morris. The Morris worm almost shut down the entire Internet in November 1998. It was a VAX/VMS and SunOS based worm that exploited known vulnerabilities in sendmail’s debugging mode, fingerd and rsh/rexec. Within few hours the worm spread allegedly to more than half of the computers on the Internet at that time.This worm is similar to almost all Linux worms today — it is fully automatic, requires no user innovation and uses known vulnerabilities of the host operating system for its replication.[2]Table 1  相似文献   
4.
We examined serum levels of a CD44 splice variant that contained variant exons 8-10 (CD44v8-10) as a tumor marker in colorectal cancer patients. We performed enzyme-linked immunosorbent assays in 81 sera obtained from 71 colorectal cancer patients and 10 healthy controls. Serum CD44v8-10 levels were significantly higher in the colorectal cancer patients than in the healthy controls (0.209 +/- 0.098 versus 0.114 +/- 0.019 OD; P < 0.01). There was a close correlation between immunohistochemical expression and serum CD44v8-10 levels. Surgical resection of the tumors resulted in a reduction of serum CD44v8-10 levels. There was no significant correlation between serum CD44v8-10 level and serosal invasion or histologic type. However, a significant correlation was observed between serum CD44v8-10 level and lymphatic or venous invasion. In addition, serum CD44v8-10 levels were significantly higher in carcinomas associated with lymph node or liver metastasis than in those without metastasis. These findings suggest the usefulness of serum CD44v8-10 level in the prediction of colorectal cancer metastasis.  相似文献   
5.
A high-performance liquid chromatographic (HPLC) procedure for quantitating ketoprofen in isopropyl myristate (IPM), a compound widely used as a receptor medium in drug diffusion studies of topical aqueous-based formulations, is developed. Previously reported HPLC assays for ketoprofen in IPM have employed relatively complex and tedious methods for purifying the IPM prior to injection onto the HPLC column. The present assay method utilizes a direct injection of the IPM-based sample onto a new reversed-phase ODS column and employs ultraviolet detection at 265 nm. Propyl paraben is employed as the internal standard. The mobile phase consists of acetonitrile-methanol-water (36:54:10, v/v/v) at a flow rate of 1.2 mL/min. The calibration curves are linear (correlation coefficient r > or = 0.988) over concentration ranges of 0.625-10 micrograms/mL and 6.25-100 micrograms/mL. The within-day and between-day precision exhibit coefficients of variation of 1.3-3.3%, and the accuracy (reported as relative error of the mean) varies from -1.9% to 0.6%. The retention times for ketoprofen and propyl paraben are approximately 2.3 and 3.3 min, respectively. The total run time per sample is approximately 7 min. The minimum quantitatable concentration is approximately 0.625 microgram/mL. The assay is stability-indicating, rapid, reproducible, sensitive, and readily adaptable for assaying other non-steroidal anti-inflammatory drugs.  相似文献   
6.
帘式涂布是一种低冲击预计量涂布方式,可用于纸和纸板的涂布、帘式涂布技术所产生的涂层为仿形涂层,因而能提供良好的纤维覆盖。在多层帘式涂布中,可以同时进行多层涂布。与单层帘式涂布相比,多层帘式涂布具有许多优点:投资成本更低、设计不同涂层性质更具灵活性、具有更大的涂布操作空间及涂层更薄等,  相似文献   
7.
Adipose-derived mesenchymal stem/stromal cells (ASCs) are an adult stem cell population able to self-renew and differentiate into numerous cell lineages. ASCs provide a promising future for therapeutic angiogenesis due to their ability to promote blood vessel formation. Specifically, their ability to differentiate into endothelial cells (ECs) and pericyte-like cells and to secrete angiogenesis-promoting growth factors and extracellular vesicles (EVs) makes them an ideal option in cell therapy and in regenerative medicine in conditions including tissue ischemia. In recent angiogenesis research, ASCs have often been co-cultured with an endothelial cell (EC) type in order to form mature vessel-like networks in specific culture conditions. In this review, we introduce co-culture systems and co-transplantation studies between ASCs and ECs. In co-cultures, the cells communicate via direct cell–cell contact or via paracrine signaling. Most often, ASCs are found in the perivascular niche lining the vessels, where they stabilize the vascular structures and express common pericyte surface proteins. In co-cultures, ASCs modulate endothelial cells and induce angiogenesis by promoting tube formation, partly via secretion of EVs. In vivo co-transplantation of ASCs and ECs showed improved formation of functional vessels over a single cell type transplantation. Adipose tissue as a cell source for both mesenchymal stem cells and ECs for co-transplantation serves as a prominent option for therapeutic angiogenesis and blood perfusion in vivo.  相似文献   
8.
A full-scale study investigated the influence of diurnal flow equalisation and prefermentation on the characteristics of sludge. The diurnal variations in the sludge concentration and the level of sludge blanket in the secondary clarifiers were evened out significantly with the use of an equalization basin. Stable conditions in the aeration basin and in the secondary clarifiers contributed to the improvements in the performance of the BNR plant. A decrease in the waste activated sludge production and an improvement in the settleability were also observed. The low WAS yield was attributed to the low yield COD compounds produced by the prefermentation, longer sludge age and constant conditions obtained by the flow equalisation. Some evidence was found that good settling properties would be related to the amount of suspended solids fed to the biological process as well as to the good performance of the biological process.  相似文献   
9.
The deactivation of hydrodemetallation catalyst was investigated in diffusion-free conditions using a model oil system. The hydrodemetallation activity of a CoMo/γ-alumina catalyst was studied using nickel or vanadyl etioporphyrins as model compounds and the hydrodesulfurization and hydrogenation activity using dibenzothiophene and naphthalene. The experiments were carried out over sulfided catalysts at 320°C and 4.83 MPa total pressure. The catalyst activity for nickel etioporphyrin hydrodemetallation was maintained at least up to 50% metal loading. The hydrogenolysis activity decreased with increasing nickel and vanadium on the catalyst but the hydrogenation activity increased. The changes in activity were attributed to the different activities of the various sulfide phases present in the catalyst system.  相似文献   
10.
The influence of the seasonal cycle of boreal forest understory has been noticed in global remote sensing of vegetation, especially in remote sensing of biophysical properties (e.g. leaf area index) of the tree-layer in a forest. A general problem in the validation of operationally produced global biophysical vegetation products is the lack of ground reference data on the seasonal variability of different land surface types. Currently, little is known about the spectral properties of the understory layers of boreal forests, and even less is known about the seasonal dynamics of the spectra. In this paper, we report seasonal trajectories of understory reflectance spectra measured in a European boreal forest. Four study sites representing different forest fertility site types were selected from central Finland. The understory composition was recorded and its spectra measured with an ASD FieldSpec Hand-Held UV/VNIR Spectroradiometer ten times during the growing period (from May to September) in 2010. Our results show that the spectral differences between and within understory types are the largest at the peak of the growing season in early July whereas in the beginning and end of the growing season (i.e. early May and late September, respectively) the differences between the understory types are marginal. In general, the fertile sites had the brightest NIR spectra throughout the growing season whereas infertile types appeared darker in NIR. Our results also indicated that a mismatch in the seasonal development of understory and tree layers does not occur in boreal forests: the understory and tree layer vegetation develop at a similar pace in the spring (i.e. there are no or only few spring ephemerals present), and the forests with the strongest seasonal dynamics in tree canopy structure (LAI) have also the strongest dynamics in understory spectra.  相似文献   
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