首页 | 本学科首页   官方微博 | 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   663篇
  免费   6篇
  国内免费   2篇
电工技术   17篇
化学工业   105篇
金属工艺   21篇
机械仪表   3篇
建筑科学   25篇
能源动力   17篇
轻工业   61篇
水利工程   1篇
石油天然气   1篇
武器工业   1篇
无线电   37篇
一般工业技术   132篇
冶金工业   187篇
原子能技术   7篇
自动化技术   56篇
  2021年   8篇
  2018年   9篇
  2017年   6篇
  2016年   5篇
  2014年   10篇
  2013年   35篇
  2012年   19篇
  2011年   25篇
  2010年   22篇
  2009年   20篇
  2008年   16篇
  2007年   16篇
  2006年   26篇
  2005年   19篇
  2004年   24篇
  2003年   24篇
  2002年   23篇
  2001年   11篇
  2000年   6篇
  1999年   13篇
  1998年   30篇
  1997年   24篇
  1996年   23篇
  1995年   18篇
  1994年   16篇
  1993年   17篇
  1992年   10篇
  1991年   9篇
  1990年   10篇
  1989年   18篇
  1988年   13篇
  1987年   9篇
  1986年   11篇
  1985年   8篇
  1984年   7篇
  1983年   7篇
  1982年   6篇
  1981年   6篇
  1980年   8篇
  1979年   7篇
  1978年   4篇
  1977年   10篇
  1976年   13篇
  1975年   4篇
  1974年   10篇
  1973年   4篇
  1972年   5篇
  1971年   4篇
  1970年   3篇
  1969年   5篇
排序方式: 共有671条查询结果,搜索用时 15 毫秒
1.
International Journal of Control, Automation and Systems - This paper proposes a method for autonomous underwater vehicles to chase sea turtles without attaching any tag to them, toward efficient...  相似文献   
2.
ALG-2, a 22-kDa penta-EF-hand protein, is involved in cell death, signal transduction, membrane trafficking, etc., by interacting with various proteins in mammalian cells in a Ca2+-dependent manner. Most known ALG-2-interacting proteins contain proline-rich regions in which either PPYPXnYP (type 1 motif) or PXPGF (type 2 motif) is commonly found. Previous X-ray crystal structural analysis of the complex between ALG-2 and an ALIX peptide revealed that the peptide binds to the two hydrophobic pockets. In the present study, we resolved the crystal structure of the complex between ALG-2 and a peptide of Sec31A (outer shell component of coat complex II, COPII; containing the type 2 motif) and found that the peptide binds to the third hydrophobic pocket (Pocket 3). While amino acid substitution of Phe85, a Pocket 3 residue, with Ala abrogated the interaction with Sec31A, it did not affect the interaction with ALIX. On the other hand, amino acid substitution of Tyr180, a Pocket 1 residue, with Ala caused loss of binding to ALIX, but maintained binding to Sec31A. We conclude that ALG-2 recognizes two types of motifs at different hydrophobic surfaces. Furthermore, based on the results of serial mutational analysis of the ALG-2-binding sites in Sec31A, the type 2 motif was newly defined.  相似文献   
3.
4.
Abstract: We have previously reported that bilberry anthocyanins exhibit an anti‐pruritic effect in a mouse model of allergic contact dermatitis. It has been reported that anthocyanins are particularly sensitive to thermal treatment and are easily hydrolyzed to anthocyanidins when exposed to high temperatures. The objective of this study was to compare the anti‐pruritic effect of anthocyanin‐rich quality‐controlled bilberry extract and anthocyanidin‐rich degraded extract using a mouse model of allergic contact dermatitis. BALB/c mice with allergic contact dermatitis induced by 4 weeks of repeated application of 2,4,6‐trinitro‐1‐chlorobenzene (TNCB) were administered Bilberon‐25 orally for 4 weeks after sensitization with TNCB. The effect of Bilberon‐25 on pruritus was evaluated by measurement of scratching behavior. RBL‐2H3 mast cells were used to investigate the effect of Bilberon‐25 on degranulation in 48/80‐stimulated mast cells. Compared with nonheated Bilberon‐25, the proportion of anthocyanins in heated Bilberon‐25 decreased, and the proportion of anthocyanidins was increased in heated‐time dependent manner. Treatment with non‐heated Bilberon‐25 significantly attenuated the TNCB‐induced increase in scratching behavior, whereas treatment with 2 h‐heated Bilberon‐25 did not. Moreover, 300 μg/mL nonheated Bilberon‐25 showed significant inhibition of degranulation in RBL‐2H3 mast cells, whereas 2 h‐heated Bilberon‐25 had no effect at any concentration studied. It is assumed that the inhibitory effect of bilberry anthocyanins on pruritus might be mediated, at least in part, by its inhibitory effect on mast cell degranulation. In conclusion, the anthocyanin‐rich but not anthocyanidin‐rich bilberry extract may be a useful dietary supplement for skin diseases involving pruritic symptoms, such as chronic allergic contact dermatitis, atopic dermatitis, and rhinitis.  相似文献   
5.
Abstract

Mechanism of C60 formation from naphthalenes was studied by quantum chemical calculations. a patch up process of T-shape dimerization of naphthalenes followed by the intramolecular ring fusion, all through radical reactions, was proposed for a possible mechanism for the C60 formation from naphthalenes. the reaction barrier was found to be less than 60-70 kcal/mol for each reaction step in this mechanism.  相似文献   
6.
The high outlet temperatures and high thermal-energy conversion efficiency of modular high-temperature gas-cooled reactors (HTGRs) enable an efficient and cost-effective integration of the reactor system with non-electricity-generation applications, such as process heat and/or hydrogen production, for the many petrochemical and other industrial processes that require temperatures between 300°C and 900°C. The U.S. Department of Energy (DOE) has selected the HTGR concept for the Next Generation Nuclear Plant (NGNP) Project as a transformative application of nuclear energy that will demonstrate emissions-free nuclear-assisted electricity, process heat, and hydrogen production, thereby reducing greenhouse-gas emissions and enhancing energy security. The objective of the DOE Advanced Gas Reactor (AGR) Fuel Development and Qualification program is to qualify tristructural isotropic (TRISO)-coated particle fuel for use in HTGRs. An overview of the program and recent progress is presented.  相似文献   
7.
Objective: To investigate strategies for broad mass isolation during outbreaks of infectious diseases. Design: A survey using a self-administered questionnaire was conducted on 300 printing company workers in Beijing, China, which was under mass isolation following the 2003 SARS outbreak, in the 7-8 months after the isolation was lifted. Main Outcome Measures: Individuals with psychological disorders were classified on the basis of scores on the 30-item General Health Questionnaire during the recovery period. Psychological disorders were observed in 49 of 187 respondents (26.2%; 95% CI = 20.2, 32.7). Results: The predicting factor with the highest correlation was income reduction, with an odds ratio of 25.0. Other items obtained were gender, range of activities, eating restrictions, restrictions in going out, disinfection of clothing, and infection control, with odds ratios of 3.2, 5.5, 3.9, 3.2, 0.2, and 0.1, respectively, and the contribution ratio was 87.7%. Conclusion: Securing income is suggested to be important in future strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
8.
Silicon nanocrystals (Si-NCs) were grown in situ in carbide-based film using a plasma-enhanced chemical vapor deposition method. High-resolution transmission electron microscopy indicates that these nanocrystallites were embedded in an amorphous silicon carbide-based matrix. Electron diffraction pattern analyses revealed that the crystallites have a hexagonal-wurtzite silicon phase structure. The peak position of the photoluminescence can be controlled within a wavelength of 500 to 650 nm by adjusting the flow rate of the silane gas. We suggest that this phenomenon is attributed to the quantum confinement effect of hexagonal Si-NCs in silicon carbide-based film with a change in the sizes and emission states of the NCs.  相似文献   
9.
Asymmetric SrCe0.95Yb0.05O3?α (SCYb) membranes were prepared by using a settlement method to deposit a thin dense SCYb layer on the green porous SCYb support, followed by conventional dry pressing and co-sintering. SCYb powder was mixed in a liquid media (isopropanol) and directly poured onto the pre-pressed green porous SCYb support placed in a beaker. After the powder fully settled onto the support, the green asymmetric sample was dried and co-sintered. The cross-sectional images of the asymmetric systems indicate that thin dense SCYb films in the asymmetric membranes had uniform thicknesses at this level of analysis and show excellent adhesion to the porous support without any undesirable defects, delamination or cracking. Further, different dense layer thicknesses (80–20 μm) were readily obtained by altering the amount of the SCYb powders in the liquid media. The minimum dense layer thickness obtained by the settlement method, with the synthesis conditions utilised in this study, was around 20 μm.  相似文献   
10.
This paper describes a 0.25-μm, 64 K×36 bit pipelined burst SRAM using a 6.156-μm2 cell. It realizes over 500-MHz operation using a lower cost double metal process, Internal 16 K×144 organization by T-shaped bit line array reduces 20% of latency, 20% of active power, and 8.5% of die size. The low power also enables us to use lower cost thin quad flat type packages. Our solution to the soft error problem, a shallow triple well structure and four-transistor cell with stacked capacitor, improved soft error rate by 3.5 orders of magnitude compared with the conventional SRAM cell  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