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   269篇
  免费   6篇
电工技术   1篇
综合类   1篇
化学工业   33篇
金属工艺   1篇
机械仪表   4篇
建筑科学   22篇
矿业工程   1篇
能源动力   3篇
轻工业   45篇
水利工程   1篇
无线电   21篇
一般工业技术   24篇
冶金工业   71篇
自动化技术   47篇
  2023年   3篇
  2021年   1篇
  2020年   8篇
  2019年   8篇
  2018年   2篇
  2017年   4篇
  2016年   5篇
  2015年   5篇
  2014年   4篇
  2013年   7篇
  2012年   13篇
  2011年   14篇
  2010年   18篇
  2009年   12篇
  2008年   11篇
  2007年   15篇
  2006年   10篇
  2005年   12篇
  2004年   11篇
  2003年   14篇
  2002年   6篇
  2001年   5篇
  2000年   6篇
  1999年   7篇
  1998年   8篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   2篇
  1993年   9篇
  1992年   2篇
  1991年   4篇
  1990年   3篇
  1989年   4篇
  1988年   4篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1983年   2篇
  1982年   2篇
  1981年   5篇
  1980年   2篇
  1979年   2篇
  1977年   1篇
  1976年   2篇
  1975年   2篇
  1974年   2篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有275条查询结果,搜索用时 15 毫秒
1.
Although today's engineering computer technology allows for precise analysis of the structural response of a building, it does not readily provide insight for economical design. Due to the complex nature of a modern tall building consisting of thousands of structural members, the traditional design method is generally highly iterative and time consuming. This paper describes an efficient computer-based technique for least-weight design of three-dimensional (3D) tall steel building frameworks under multiple lateral loading conditions. Stiffness constraints in terms of interstorey drifts are considered and optimum discrete member sizes are automatically selected from databases of commercial standard steel sections. The technique is remarkably efficient and the optimum design generally converges in a few cycles. The designs of two 3D lateral-load resisting building frameworks are presented as illustrations. The effectiveness and suitability of the technique for the design of large-scale tall steel building frameworks are discussed.  相似文献   
2.
Product development is a collaborative activity more often than ever carried out by distributed design teams. It is critical to determine how sketches are used in such environments in order to improve the design process. Sketches produced by students participating in a collaborative design project of three European Universities are classified according to the intention of the designer when producing a sketch, the level of detail shown in the sketch and the phase when the sketch was produced. The adapted classification system used in this paper helps to analyse type of sketches with most variety of ideas. Furthermore, this paper reviews which type of sketches offers the most potential to be further developed. Results show that persuasive sketches offer the broadest range of ideas since they are produced as a combination of ideas from brainstorming sessions. Shared sketches help to achieve consensus in decision-making since the sketches are most likely to be produced by the entire group rather than individually.  相似文献   
3.
4.
5.
Despite the considerable scholarship focused on infrastructure investment in the developing world and the substantial sums of money spent each year on developing-country infrastructure, little attention has been given to understanding the drivers of conflict that shape the trajectory and cost structures of these massive investments. The manifestation of conflict among stakeholders in infrastructure projects ranges from the renegotiation of contract terms by project partners to popular protests among consumers of privatized services. The principal objective of this research is to identify combinations of country, project, and stakeholder factors that are associated with the emergence of legal and political conflict within natural gas and oil pipeline projects and water supply concessions and leases. The analysis includes data from 26 infrastructure projects spanning 31 countries and uses an analytical approach derived from Boolean algebra. Country-level characteristics, such as extent of democracy and rate of international NGO membership, are found to be important elements in the recipes for conflict among water supply projects but not for pipeline projects. Local impacts such as service price increases (water supply) and limited provision of oil and gas to the project host country (pipelines) are also important drivers of conflict for both subsectors. The involvement of one or more international financial institutions is also associated with the emergence of conflict in projects. Contrary to expectations, public consultation is associated with conflict in both subsectors. Overall, the study findings suggest that several factors associated with conflict in infrastructure projects can be minimized with careful project design.  相似文献   
6.
Soybean agglutinin (SBA) protein, also known as soybean lectin, is regarded as an anti‐nutrient due to its negative effect on the ability of monogastric animals to gain weight following consumption of raw soybean seed. Historically, SBA has been measured using a time‐consuming and cumbersome hemagglutination procedure. The objective of our research was to obtain a validated methodology that is precise and accurate in the measurement of SBA while allowing minimally equipped laboratories to effectively conduct the analysis, thus our focus was on evaluating an existing commercially available ELISA, an enzyme‐linked‐lectin‐assay (ELLA), and a hybrid ELISA/ELLA. A new ELLA technique that can detect and quantify lectins was chosen and modified specifically for the quantitation of SBA in soybean seed. The proposed ELLA methodology is similar to a standard sandwich ELISA, and uses polyacrylamide‐linked N‐acetylgalactosamine (Gal–NAc–PAA) for a capture phase and the biotinylated version (Gal–NAc–PAA–Biotin) for detection. Based upon the validation data, the ELLA method can precisely and accurately determine soybean lectin levels in soybean seed. The validated ELLA method was used to quantify SBA in nine commercial soybean varieties introduced between 1972 and 2008 and demonstrated that the natural variability of SBA is subject to the effects of genotype and environment.  相似文献   
7.
8.
9.
10.
The Galbeta1-3GalNAcalpha (TF antigen)-binding lectin (ABL) from the common edible mushroom (Agaricus bisporus) has a potent anti-proliferative effect without any apparent cytotoxicity. This unusual combination of properties prompted investigation of its mechanism of action. In contrast to soluble lectin, agarose-immobilized, and hence noninternalizable ABL had no effect on proliferation of HT29 colon cancer cells. Electron microscopy of HT29 cells incubated with fluorescein- and gold-conjugated ABL showed internalization of the lectin into endocytotic vesicles and multivesicular bodies. Confocal microscopy showed perinuclear accumulation of fluorescein isothiocyanate-conjugated lectin, which also inhibits HT29 cell proliferation, raising the possibility that the lectin might interfere with nuclear pore function. Transport of heat shock protein 70 into the nucleus in response to heat shock was blocked by preincubation of HT29 cells for 6 h with 40 micrograms/ml ABL. In digitonin-permeabilized cells, nuclear uptake of bovine albumin conjugated to a nuclear localization sequence (NLS)-containing peptide was also inhibited by a 15-min preincubation with 40-100 micrograms/ml ABL. In contrast, serum-stimulated nuclear translocation of mitogen-activated protein kinase, which is NLS-independent, was not affected by pretreatment of cells with the lectin. These results suggest that the anti-proliferative effect of ABL is likely to be a consequence of the lectin trafficking to the nuclear periphery, where it blocks NLS-dependent protein uptake into the nucleus.  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