首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   118篇
  免费   1篇
工业技术   119篇
  2023年   1篇
  2022年   7篇
  2021年   3篇
  2020年   2篇
  2019年   1篇
  2018年   1篇
  2017年   2篇
  2016年   6篇
  2015年   3篇
  2014年   6篇
  2013年   5篇
  2012年   2篇
  2011年   7篇
  2010年   1篇
  2009年   7篇
  2008年   7篇
  2007年   2篇
  2006年   3篇
  2005年   2篇
  2004年   4篇
  2003年   4篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1998年   8篇
  1997年   6篇
  1996年   5篇
  1995年   1篇
  1993年   2篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1986年   1篇
  1985年   3篇
  1981年   1篇
  1980年   2篇
  1979年   3篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
排序方式: 共有119条查询结果,搜索用时 15 毫秒
1.
2.
We introduce a new family of fungal protease inhibitors with β-trefoil fold from the mushroom Coprinopsis cinerea, named cocaprins, which inhibit both cysteine and aspartic proteases. Two cocaprin-encoding genes are differentially expressed in fungal tissues. One is highly transcribed in vegetative mycelium and the other in the stipes of mature fruiting bodies. Cocaprins are small proteins (15 kDa) with acidic isoelectric points that form dimers. The three-dimensional structure of cocaprin 1 showed similarity to fungal β-trefoil lectins. Cocaprins inhibit plant C1 family cysteine proteases with Ki in the micromolar range, but do not inhibit the C13 family protease legumain, which distinguishes them from mycocypins. Cocaprins also inhibit the aspartic protease pepsin with Ki in the low micromolar range. Mutagenesis revealed that the β2-β3 loop is involved in the inhibition of cysteine proteases and that the inhibitory reactive sites for aspartic and cysteine proteases are located at different positions on the protein. Their biological function is thought to be the regulation of endogenous proteolytic activities or in defense against fungal antagonists. Cocaprins are the first characterized aspartic protease inhibitors with β-trefoil fold from fungi, and demonstrate the incredible plasticity of loop functionalization in fungal proteins with β-trefoil fold.  相似文献   
3.
Glioblastoma (GBM) is the most common and deadly primary brain tumor in adults. Understanding GBM pathobiology and discovering novel therapeutic targets are critical to finding efficient treatments. Upregulation of the lysosomal cysteine carboxypeptidase cathepsin X has been linked to immune dysfunction and neurodegenerative diseases, but its role in cancer and particularly in GBM progression in patients is unknown. In this study, cathepsin X expression and activity were found to be upregulated in human GBM tissues compared to low-grade gliomas and nontumor brain tissues. Cathepsin X was localized in GBM cells as well as in tumor-associated macrophages and microglia. Subsequently, potent irreversible (AMS36) and reversible (Z7) selective cathepsin X inhibitors were tested in vitro. Selective cathepsin X inhibitors decreased the viability of patient-derived GBM cells as well as macrophages and microglia that were cultured in conditioned media of GBM cells. We next examined the expression pattern of neuron-specific enzyme γ-enolase, which is the target of cathepsin X. We found that there was a correlation between high proteolytic activity of cathepsin X and C-terminal cleavage of γ-enolase and that cathepsin X and γ-enolase were colocalized in GBM tissues, preferentially in GBM-associated macrophages and microglia. Taken together, our results on patient-derived material suggest that cathepsin X is involved in GBM progression and is a potential target for therapeutic approaches against GBM.  相似文献   
4.
There are currently no epidemiological studies on health effects of long-term exposure to ultrafine particles (UFP), largely because data on spatial exposure contrasts for UFP is lacking. The objective of this study was to develop a land use regression (LUR) model for UFP in the city of Amsterdam. Total particle number concentrations (PNC), PM10, PM2.5, and its soot content were measured directly outside 50 homes spread over the city of Amsterdam. Each home was measured during one week. Continuous measurements at a central urban background site were used to adjust the average concentration for temporal variation. Predictor variables (traffic, address density, land use) were obtained using geographic information systems. A model including the product of traffic intensity and the inverse distance to the nearest road squared, address density, and location near the port explained 67% of the variability in measured PNC. LUR models for PM2.5, soot, and coarse particles (PM10, PM2.5) explained 57%, 76%, and 37% of the variability in measured concentrations. Predictions from the PNC model correlated highly with predictions from LUR models for PM2.5, soot, and coarse particles. A LUR model for PNC has been developed, with similar validity as previous models for more commonly measured pollutants.  相似文献   
5.
Chelate-induced remediation has been proposed as an effective tool for the extraction of lead (Pb) from contaminated soils by plants. However, side-effects, mainly mobilization and leaching of Pb, raise environmental concerns. Biodegradable, synthetic organic chelate ethylenediaminedisuccinic acid (EDDS), and commonly used ethylenedimanetetraacetic acid (EDTA) were used for induced phytoextraction with a test plant Brassica rapa and in situ washing of soil contaminated with 1350 mg/kg of Pb. Horizontal permeable barriers were placed 20 cm deep in soil columns and tested for their ability to prevent leaching of Pb. The reactive materials in the barriers were nutrient enriched vermiculite, peat or agricultural hydrogel, and apatite. EDTA and EDDS addition increased Pb concentrations in the test plant by 158 and 89 times compared to the control, to 817 and 464 mg/kg, respectively. In EDTA treatments, approximately 25% or more of total initial soil Pb was leached in single cycle of chelate addition. In EDDS treatments, 20% of the initial Pb was leached from columns with no barrier, while barriers with vermiculite or hydrogel and apatite decreased leaching by more than 60 times, to 0.35%. 11.6% of total initial Pb was washed from the soil above the barrier with vermiculite and apatite, where almost all leached Pb was accumulated. Results indicate that use of biodegradable chelate EDDS and permeable barriers may lead to environmentally safe induced Pb phytoextraction and in situ washing of Pb.  相似文献   
6.
Marek  J.  Mohyla  I.  Kos  J.  Krček  M. 《Journal of Applied Electrochemistry》1979,9(1):89-100
Sintered negative electrodes for nickel-cadmium secondary cells were studied. Model electrodes prepared by means of three different impregnation methods were evaluated. It was demonstrated that the impregnation procedure may affect properties of active mass and the service life of electrodes in a significant way.  相似文献   
7.
Pigmentation of murine cardiac tricuspid valve leaflet is associated with melanocyte concentration, which affects its stiffness. Owing to its biological and viscoelastic nature, estimation of the in situ stiffness measurement becomes a challenging task. Therefore, quasi-static and nanodynamic mechanical analysis of the leaflets of the mouse tricuspid valve is performed in the current work. The mechanical properties along the leaflet vary with the degree of pigmentation. Pigmented regions of the valve leaflet that contain melanocytes displayed higher storage modulus (7–10 GPa) than non-pigmented areas (2.5–4 GPa). These results suggest that the presence of melanocytes affects the viscoelastic properties of the mouse atrioventricular valves and are important for their proper functioning in the organism.  相似文献   
8.
The methods and instrumentation for carrying out precise measurements of the equivalent electrical parameters of piezoelectric crystals have been developed. An accuracy exceeding 0.05% has been achieved with low power dissipation in the crystal permitting the use of this system at low temperatures and particularly in applications concerning the detection of gravitational radiation.  相似文献   
9.
A quartz resonator thin film monitor of exceptionally high accuracy and resolution has been developed. It is capable of providing measurements with an effective resolution of 0.001 nm and a corresponding relative accuracy of about 1% for a 0.100-nm-thick film of gold. A novel dual oscillator and mixer using integrated circuits is also described.  相似文献   
10.
We have analyzed all available data including birth certificates, maternity records, pediatric records, and pathology reports of spontaneous and induced abortions and newborn deaths to determine the frequency of congenital anomalies of the central nervous system. We found 76 infants (34 males, 39 females and 3 of undetermined sex) with CNS anomalies during the 1990-93 period. In the same period there were 23,425 births. The frequency of CNS anomalies in this period was 32,4/10,000 births. These results are at variance with conclusions of previously published and incomprehensive studies in Croatia. Therefore, a systematic follow-up of the autopsy findings of induced and spontaneous abortions and newborn deaths in the epidemiology of CNS anomalies is clearly needed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号