全文获取类型
收费全文 | 116篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 21篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
能源动力 | 3篇 |
轻工业 | 5篇 |
无线电 | 35篇 |
一般工业技术 | 12篇 |
冶金工业 | 23篇 |
自动化技术 | 23篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 10篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1985年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有125条查询结果,搜索用时 15 毫秒
11.
Wei Wuli Shinn-Zong Lin Shee-Ping Chen Bakhos A. Tannous Wen-Sheng Huang Peng Yeong Woon Yang-Chang Wu Hsueh-Hui Yang Yi-Cheng Chen Renata Lopes Fleming Jack T. Rogers Catherine M. Cahill Tsung-Jung Ho Tzyy-Wen Chiou Horng-Jyh Harn 《International journal of molecular sciences》2022,23(18)
Presenilin-1 (PSEN1) is a crucial subunit within the γ-secretase complex and regulates β-amyloid (Aβ) production. Accumulated evidence indicates that n-butylidenephthalide (BP) acts effectively to reduce Aβ levels in neuronal cells that are derived from trisomy 21 (Ts21) induced pluripotent stem cells (iPSCs). However, the mechanism underlying this effect remains unclear. This article aims to investigate the possible mechanisms through which BP ameliorates the development of Alzheimer’s disease (AD) and verify the effectiveness of BP through animal experiments. Results from RNA microarray analysis showed that BP treatment in Ts21 iPSC-derived neuronal cells reduced long noncoding RNA (lncRNA) CYP3A43-2 levels and increased microRNA (miR)-29b-2-5p levels. Bioinformatics tool prediction analysis, biotin-labeled miR-29b-2-5p pull-down assay, and dual-luciferase reporter assay confirmed a direct negative regulatory effect for miRNA29b-2-5p on lnc-RNA-CYP3A43-2 and PSEN1. Moreover, BP administration improved short-term memory and significantly reduced Aβ accumulation in the hippocampus and cortex of 3xTg-AD mice but failed in miR-29b-2-5p mutant mice generated by CRISP/Cas9 technology. In addition, analysis of brain samples from patients with AD showed a decrease in microRNA-29b-2-5p expression in the frontal cortex region. Our results provide evidence that the LncCYP3A43-2/miR29-2-5p/PSEN1 network might be involved in the molecular mechanisms underlying BP-induced Aβ reduction. 相似文献
12.
A polymerase chain reaction (PCR) method for the rapid diagnosis of tuberculous meningitis (TBM) was used to study prospectively 47 cerebrospinal fluid (CSF) samples from 45 patients. Twenty CSF samples were from patients with clinically suspected TBM and another 27 samples came from patients without clinically suspected TBM. Mycobacterial DNA was detected in 15 CSF samples (14 from patients with clinically suspected TBM and 1 from a patient not suspected of having TBM). Of the PCR-positive samples, 4 were also positive for mycobacterial culture. However, 32 PCR-negative samples were all culture-negative. All samples were negative for the acid-fast bacillus by direct smear. The single PCR-positive patient in the clinically unsuspected TBM group was initially diagnosed as suffering from aseptic meningitis on the basis of his clinical features. The mycobacterial culture of his CSF specimen was also positive and a revised diagnosis of an aseptic type of TBM was made. The estimations of specificity and sensitivity in this study were 100% and 70% respectively. The results showed that using a PCR to detect mycobacterial DNA in CSF for the early diagnosis of TBM is not only a rapid but also an accurate method. 相似文献
13.
Bromine is used as the building block for some of the most effective flame retarding agents available to the plastics industry today. They are used to protect against the risk of accidental fires in a wide range of Electrical and Electronic Equipment (EEE). Brominated flame retardants (BFRs), as all flame retardants, act to decrease the risk of fire by increasing the fire resistance of the materials in which they are applied. There is a perception that BFRs affect adversely the end‐of‐life management of plastics through formation of Polybrominated Dibenzo Dioxins and Dibenzo Furans (PBDD/F). In fact, there exists a wide range of data and practical experience demonstrating that the end‐of‐life management of plastics containing BFRs is fully compliant with legislation setting the strictest limit values for PBDD/F and is fully compatible with an integrated waste management concept. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
14.
In experimental schistosomiasis, sera of mice multiply vaccinated with radiation-attenuated cercariae of Schistosoma mansoni passively transfer resistance against cercarial challenge to naive mice. To further characterize these sera, we tested their protective capacities in two mouse strains (C57BL/6J and CBA/J) and compared the antigen-specific isotype compositions of the different protective sera by means of the enzyme-linked immunosorbent assay. By using an array of purified schistosomal antigens, the patterns of antibody titers and isotypes differed for each experimental group and antigen. In the most-protective C57BL/6J sera, high levels of immunoglobulin G1 (IgG1), IgG2a, and IgG2b bound to heat shock protein 70 and the integral membrane protein Sm23, whereas recognition of these antigens by less-protective CBA/J sera was lower. Glutathione S-transferase (GST) was recognized predominantly by IgM antibodies of all vaccinated groups, and a significant portion of this response was directed against carbohydrate epitopes. Antibodies specific for triosephosphate isomerase, paramyosin, and Sm32 (hemoglobinase) were present in less-protective sera and thus seem less relevant for passive transfer of resistance. The results of this study suggest a contribution of IgG antibodies specific for heat shock protein 70 and Sm23, and possibly a contribution of GST-specific IgM antibodies, to the protective effect of sera from C57BL/6J mice vaccinated with irradiated cercariae. 相似文献
15.
Wireless Networks - Key distribution is one of the most fundamental cryptographic primitives that can establish secure group communications in both centralized and distributed networks. A one-time... 相似文献
16.
In this paper, we propose an approach to reusing requirements specification, called task-based specifications in conceptual graphs (TBCG). In TBCG, task-based specification methodology is used to serve as the mechanism to structure the knowledge captured in conceptual models, and conceptual graphs are adopted as the formalism to express requirements specification. TBCG provides several mechanisms to facilitate the reuse of formal specifications: a contextual retrieval mechanism to support context-sensitive specifications retrieval and incremental context acquisition, a graph matching mechanism to compute the similarity between two graphs based on the semantic match and fuzzy logic, and a paraphraser to serve as an explanation mechanism for the retrieval specifications. ©1999 John Wiley & Sons, Inc. 相似文献
17.
Hilde Lea Lein Kjell Wiik Mari-ann Einarsrud Tor Grande Edgar Lara-curzio 《Journal of the American Ceramic Society》2006,89(9):2895-2898
Steady-state compressive creep rate of La0.5 Sr0.5 Fe0.5 Co0.5 O3−δ (LSFC) and La0.5 Sr0.5 CoO3−δ (LSC) is reported in the temperature region 900°–1050°C and stress range 5–28 MPa. The stress exponents for the two materials were 1.71±0.18 and 1.24±0.15, respectively. The activation energy for creep was considerably higher for LSC (619±56 kJ/mol) than for LSFC (392±28 kJ/mol). The grain size exponent for LSC was 1.28±0.14. Considerably higher creep rates were observed for both materials in N2 compared with air. Relaxation by creep of chemical-induced stresses in oxygen-permeable membranes is addressed, especially at low partial pressure of oxygen. 相似文献
18.
A revised scientific instrument to measure simultaneously kinetic temperatures of different atoms from their optical emission profile is reported. Emission lines are simultaneously detected using one single scanning Fabry-Perot-interferometer (FPI) for a combined spectroscopic setup to acquire different emission lines simultaneously. The setup consists in a commercial Czerny-Turner spectrometer configuration which is combined with a scanning Fabry-Perot interferometer. The fast image acquisition mode of an intensified charge coupled device camera allows the detection of a wavelength interval of interest continuously while acquiring the highly resolved line during the scan of the FPI ramp. Results using this new setup are presented for the simultaneous detection of atomic nitrogen and oxygen in a high enthalpy air plasma flow as used for atmospheric re-entry research and their respective kinetic temperatures derived from the measured line profiles. The paper presents the experimental setup, the calibration procedure, and an exemplary result. The determined temperatures are different, a finding that has been published so far as due to a drawback of the experimental setup of sequential measurements, and which has now to be investigated in more detail. 相似文献
19.
Zheng Zhang Yanan Liu Qinyuan Zuo Lein Harn Shuo Qiu Yuan Cheng 《计算机、材料和连续体(英文)》2020,64(2):1261-1280
Physical Unclonable Functions (PUFs) can be seen as kind of hardware oneway functions, who are easily fabricated but difficult to clone, duplicate or predict.
Therefore, PUFs with unclonable and unpredictable properties are welcome to be applied
in designing lightweight cryptography protocols. In this paper, a Basic Key Distribution
Scheme (Basic-KDS) based on PUFs is firstly proposed. Then, by employing different
deployment modes, a Random Deployment Key Distribution Scheme (RD-KDS) and a
Grouping Deployment Key Distribution Scheme (GD-KDS) are further proposed based
on the Basic-KDS for large scale wireless sensor networks. In our proposals, a sensor is
not pre-distributed with any keys but will generate one by the embedded PUF when
receiving a challenge from the gateway, which provides perfect resilience against sensor
capture attacks. Besides, the unclonable and unpredictable properties of PUF guarantee
the key uniqueness and two-way authentication. Analysis and experiment results show
that our proposals have better performances in improving the resilience, secureconnectivity, and efficiency as compared to other schemes. 相似文献
20.
BACKGROUND: Determining the ratio of free to total prostate specific antigen (f-PSA to t-PSA, calculated as the percentage of f-PSA [f-PSA%]) in serum allow for a clearer distinction between patients with prostate carcinoma (PCa) and patients with benign prostate hyperplasia (BPH) than determining the level of t-PSA alone. To find influencing factors on f-PSA%, the authors investigated prostate volume, TNM classification, and tumor stage. METHODS: The authors measured f-PSA and t-PSA in 36 men with untreated PCa (tumor classification: T1, 2, 3pNO, MO), 44 patients with BPH, and 54 healthy controls. Prostate volume was determined by transrectal ultrasound. RESULTS: The median values of t-PSA and f-PSA% were 7.8 micrograms/L and 10.5% in PCa patients, 4.3 micrograms/L and 20.8% in patients with BPH, and 1.4 micrograms/L and 23.6% in the control group. Patients with PCa had a significantly lower proportion of f-PSA than BPH patients and healthy men. There was no correlation of f-PSA% to TNM stage or tumor grade. In PCa patients a significant positive correlation (correlation coefficient [r] = 0.51, P < 0.001) was found between f-PSA% and prostate volume, whereas there was no significant correlation in BPH patients (r = -0.27, P > 0.05). There was a significant difference in f-PSA% between PCa and BPH patients with prostate volumes smaller than 40 cm3 (9.0% vs. 21.6%, P < 0.01) but not between patients in these 2 groups with prostate volumes exceeding 40 cm3 (15.1% vs. 18.2%, P = 0.11). CONCLUSIONS: Determining the ratio of f-PSA to t-PSA to discriminate between PCa and BPH patients yields significant results only in men with a prostate volume of less than 40 cm3. 相似文献