全文获取类型
收费全文 | 344篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 70篇 |
金属工艺 | 9篇 |
机械仪表 | 11篇 |
建筑科学 | 5篇 |
能源动力 | 18篇 |
轻工业 | 36篇 |
石油天然气 | 4篇 |
无线电 | 53篇 |
一般工业技术 | 63篇 |
冶金工业 | 36篇 |
原子能技术 | 13篇 |
自动化技术 | 35篇 |
出版年
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 20篇 |
2012年 | 12篇 |
2011年 | 17篇 |
2010年 | 13篇 |
2009年 | 14篇 |
2008年 | 19篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 20篇 |
2004年 | 11篇 |
2003年 | 14篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 19篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1969年 | 1篇 |
1968年 | 3篇 |
1966年 | 1篇 |
1957年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有354条查询结果,搜索用时 0 毫秒
41.
Kamath R.R. Mansour-Cole D.M. Apana R. 《Engineering Management, IEEE Transactions on》1993,40(3):293-299
Existing knowledge about the correlates of innovation and the context of strategic decisions is used to develop propositions about the differences in the correlates of innovation in marketing and manufacturing functions. The theoretical model proposed is eclectic: it draws upon theory development in the fields of economics, engineering management, and corporate strategy. It is proposed that manufacturing managers link their innovation decisions to their assessment of the product's uniqueness in comparison with competitor's products. In contrast, marketing managers link their innovation decisions to the clarity of innovation objectives based on the customers' needs. The analysis of data from key informants in 172 firms is used to test the propositions. Whereas product uniqueness and clarity are significant correlates of innovation in the total sample, support is found for the proposition that the manufacturing subgroup focuses more on clarity 相似文献
42.
JS Anant L Desnoyers M Machius B Demeler JC Hansen KD Westover J Deisenhofer MC Seabra 《Canadian Metallurgical Quarterly》1998,37(36):12559-12568
Rab proteins are geranylgeranylated on one or two C-terminal cysteines by Rab geranylgeranyl transferase (RabGGTase). The reaction is dependent on a Rab-binding protein, termed Rab escort protein (REP). Here, we studied the role of REP in the geranylgeranylation reaction. We first characterized the interaction between REP and ungeranylgeranylated Rab using analytical ultracentrifugation and a fluorescence-based assay. We measured an equilibrium dissociation constant of 0.2 microM for the formation of a 1:1 REP-Rab complex and showed that this interaction relies mostly on ionic bonds and does not involve the two C-terminal cysteine residues. Second, we show that REP is required for recognition of Rab by RabGGTase and therefore that the REP-Rab complex is the true substrate for RabGGTase. Third, we show that free REP inhibits the geranylgeranylation reaction, suggesting that the complex is recognized by RabGGTase primarily via a REP-binding site. Our data suggest a model whereby REP behaves kinetically as an essential activator of the reaction. 相似文献
43.
Patients with cirrhosis of the liver have increased hepatic and gastrointestinal lymph flow that may contribute to the formation of ascites and pleural effusions. Increased lymph flow, which is due to postsinusoidal portal hypertension, causes a high rate of flow through the thoracic duct. Because of the high flow rates, disrupted lymphatic vessels in patients with cirrhosis of the liver may fail to close, a situation that results in chylous ascites, pleural effusions, or chylous fistulas. Chylous fistulas deplete proteins, fluid, and lymphocytes and thus lead to volume depletion and coagulopathy. Herein we describe an unusual case in which a high-output traumatic thoracic duct-cutaneous fistula developed in a patient with cirrhosis and led to volume depletion and coagulopathy. Correction of the portal hypertension with placement of a transjugular intrahepatic portosystemic shunt led to closure of the fistula and normalization of accompanying metabolic abnormalities. 相似文献
44.
Adaptive-modulation schemes are designed that yield the minimum outage probability for wireless systems with strict delay constraints, under the assumption of perfect causal channel state information at the transmitter and receiver. Numerical results indicate that the proposed schemes significantly outperform adaptive schemes designed to maximize the average rate. 相似文献
45.
This is a multifaceted study on the characterization and quantification of damage to the hair fiber surface caused by photochemical and cosmetic chemical oxidative processes. Unique techniques were used, including a microfluorometric method that had been adapted to characterize and quantify the delipidation and acidification of the human hair surface during light exposure and cosmetic chemical grooming processes such as bleaching. During photochemical and chemical oxidation, breakdown of the lipid domains (also called the F‐layer) of the outer b‐layer occurs on the exposed scale faces and cysteic acid groups are generated on the cuticle cell surface. The newly formed acid functionalities can be tagged with the cationic fluorochrome Rhodamine B, allowing not only quantification of the level of progressive acidification but also localization of the newly formed acid functionalities. On the other hand, the negative charges generated on the hair surface by oxidation can also bind low molecular weight quaternary cationic conditioning compounds such as cetyltrimethylammonium bromide. This process can be considered a relipidation by adsorption. We have shown that the entire process of delipidation/acid formation and subsequent relipidation by adsorption on the scale faces can be quantified by X‐ray photoelectron spectroscopy. Since X‐ray photoelectron spectroscopy analysis is highly sensitive and able to detect atomic species at the very surface of the hair fibers, receiving signals from an escape depth as shallow as 25 Å, it appeared ideal for the characterization of treatment‐induced changes in the hair surface. However, X‐ray photoelectron spectroscopy provides an average elemental composition of the hair surface including scale faces and scale edges. The microfluorometric technique, on the other hand, can distinguish progressive delipidation of the scale faces from changes occurring at the broken scale edges. This distinction was shown and characterized in detail by slow speed microfluorometric scanning of the hair surface. Chemical and photochemical oxidative processes at the hair surface result in certain collateral effects. Particularly changes in surface wettability and fiber friction are of significance to the cosmetic chemist because they affect the spreading and wicking of products in hair as well as the managability and the body of hair assemblies. Methods of characterizing these effects are discussed briefly. 相似文献
46.
B. V. Kamath J. D. Mehta S. L. Bafna 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1975,25(10):743-751
The u.v. absorption spectra of 22 monosubstituted and 19 disubstituted benzoic acids have been studied in water or aqueous dioxan over a pH range of about 1–8. The isosbestic points have been measured and the results are discussed. 相似文献
47.
The problem presented to the Advanced Telecommunications Institute (ATI) at Stevens Institute of Technology involved providing monthly updates of a Global Positioning System (GPS) database. The Electronic Database Delivery (EDD) system which ATI developed for AlliedSignal instantly delivers the latest navigational data online. There is no delay in receiving the product once ordered and authorized. The EDD system “remembers” a user who returns within 28 days, recalling the date and type of the previous GPS database purchase. The EDD environment integrates CyberCash, a commercial transaction provider, to approve all online credit card transactions. The EDD product design includes many levels of security, including a Netscape Secure Commerce Server, CyberCash transaction security and AlliedSignal's own application-level security 相似文献
48.
49.
G. Subramanian V. V. S. Raveendra M. Gopalakrishna Kamath 《International journal for numerical methods in engineering》1994,37(10):1779-1789
A simple and robust boundary triangulation algorithm is proposed and, based on it, completely automatic Delaunay mesh generation procedures are developed. The algorithm is equally applicable to convex, non-convex and multiply connected planar domains. In this approach, given the nodes, the number of triangles formed is precisely known and any desired control over mesh generation is possible. 相似文献
50.
Jalaleddin Farsa Anant R. Kukreti Charles W. Bert 《International journal for numerical methods in engineering》1993,36(14):2341-2356
In this paper a differential quadrature method is presented for computation of the fundamental frequency of a thin laminated rectangular plate. The partial differential equations of motion for free vibration are solved for the boundary conditions by approximating them by substituting weighted polynomials functions for the differential operator. By doing this, the coupled partial differential equations of motion are reduced to sets of homogeneous algebraic equations. These sets of homogeneous algebraic equations are combined to give a set of general eigenvalue equations for the problem. Three types of laminated plate problems, which include symmetric, antisymmetric cross-ply, and symmetric, balanced angle-ply laminates, are analysed by the method and the results obtained are compared with solutions reported in the literature for other numerical methods. The effects of the level of discretization on the accuracy and rate of convergence of the results are also discussed. The method presented gives accurate results and is found to use not much computer time. 相似文献