全文获取类型
收费全文 | 490篇 |
免费 | 32篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 136篇 |
金属工艺 | 14篇 |
机械仪表 | 19篇 |
建筑科学 | 12篇 |
矿业工程 | 1篇 |
能源动力 | 14篇 |
轻工业 | 57篇 |
水利工程 | 1篇 |
石油天然气 | 4篇 |
无线电 | 36篇 |
一般工业技术 | 99篇 |
冶金工业 | 75篇 |
原子能技术 | 4篇 |
自动化技术 | 49篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 16篇 |
2021年 | 25篇 |
2020年 | 14篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 17篇 |
2016年 | 18篇 |
2015年 | 14篇 |
2014年 | 23篇 |
2013年 | 32篇 |
2012年 | 27篇 |
2011年 | 27篇 |
2010年 | 24篇 |
2009年 | 16篇 |
2008年 | 18篇 |
2007年 | 19篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 18篇 |
1997年 | 20篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有523条查询结果,搜索用时 15 毫秒
1.
Maria A. Ospina Monica Pizarro Thierry Tran Julien Ricci John Belalcazar Jorge L. Luna Luis F. Londoño Sandra Salazar Hernan Ceballos Dominique Dufour Luis A. Becerra Lopez-Lavalle 《International Journal of Food Science & Technology》2021,56(3):1343-1353
The objective of this study was to characterise the nutritional potential of leaves and identify a diversity centre with low cyanide and high nutrient content among 178 Latin American cassava genotypes. This field-based collection represents the seven diversity centres, held at The International Center for Tropical Agriculture (CIAT Palmira, Colombia) by the Cassava Program. The cyanide, all-trans-β-carotene and lutein concentrations in cassava leaves ranged from 346 to 7484 ppm dry basis (db), from 174–547 μg g−1 db and 15–181 μg g−1 db, respectively. Cassava leaves also showed significant levels of essential amino acids leucine, lysine, phenylalanine, valine and threonine, and average total protein content of 26.24 g 100 g−1 db. Among seven diversity centres, South American rainforest group showed low cyanide and high carotene content in leaves. In addition, VEN77 and PAN51 genotypes stood out for having low cyanide in leaves and roots and high carotene in leaves. This genetic diversity can be used to select high potential progenitors for breeding purposes. 相似文献
2.
IR与RS-232的匹配技术 总被引:2,自引:0,他引:2
TedSalazar 《电子设计应用》2004,(3):86-87
现代电子设备通常包含最新的数据通信接口,以实现更高的数据率或增进用户的便利性。红外技术(IR)是数据通信接口的一个很好例子,但有时单独使用这种最新接口还是不够的,设备还需要与采用传统接口如RS-232的老设备兼容才会被用户所接受。因此,常见的红外技术和RS-232共存于同一设备中。 相似文献
3.
A fundamental problem for regulatory networks is to understand the relation between form and function: to uncover the underlying design principles of the network. Circadian clocks present a particularly interesting instance, as recent work has shown that they have complex structures involving multiple interconnected feedback loops with both positive and negative feedback. While several authors have speculated on the reasons for this, a convincing explanation is still lacking.We analyse both the flexibility of clock networks and the relationships between various desirable properties such as robust entrainment, temperature compensation, and stability to environmental variations and parameter fluctuations. We use this to argue that the complexity provides the flexibility necessary to simultaneously attain multiple key properties of circadian clocks. As part of our analysis we show how to quantify the key evolutionary aims using infinitesimal response curves, a tool that we believe will be of general utility in the analysis of regulatory networks. Our results suggest that regulatory and signalling networks might be much less flexible and of lower dimension than their apparent complexity would suggest. 相似文献
4.
A. Ureña J. M. Gomez De Salazar J. Quiñones S. Merino J. Martin 《Journal of Materials Science》1996,31(3):807-817
Diffusion bonds have been produced between sheets of an Al-Li-Cu-Mg-Zr alloy using aluminium-4% copper vapour deposited metallic interlayers. Microstructural changes occurred both in the parent alloy and in the bond interface after diffusion bonding cycles and post-bonding heat treatments were analysed. Different metallographic techniques (light microscopy, scanning and transmission electron microscopy) have been used. Diffusion bonding trials were carried out using the same alloy (AA8090), both in non-superplastic (T6) and superplastic conditions. Differences in their behaviours in relation to diffusion bonding were observed. 相似文献
5.
F. A. Calvo J. M. Guilemany J. M. Gomez de Salazar A. Urena 《Metallurgical and Materials Transactions B》1988,19(1):165-170
The present work studies the surface evolution of cinnabar, when it is leached with HBr acid for different conditions. The
dynamicin situ test has been studied by scanning electron microscopy and EDS techniques. According to the acid condition, time, and temperature,
the HgS presents different mechanisms of dissolution, and the results prove that the cinnabar does not present “memory effect”,
as proposed by other authors.16 相似文献
6.
The therapeutic panorama of immunomodulation and its effects on the modification of the immune reaction is reviewed. Particular reference is made to the transfer factor as a therapeutic element in bronchial asthma, which insures its efficacy or innocuity. 相似文献
7.
In this work, we investigate the linear viscoelastic response of high molecular weight ethylene/1‐hexene copolymers, characterized by a narrow molecular weight distribution and comonomer content in the range from 0 to 10 mol %. A variation in the entanglement plateau modulus has been found in agreement with the recently developed packing length model. The packing model applied to viscoelastic data suggests decreased values of the characteristic ratio, accordingly with recent computer simulation results. The flow activation energy increases as the side chain content increases. This feature is thought to be related to the mobility of the molecules. The presence of side branches due to the comonomer hinders the mobility of the molecules, and increases the thermal barrier for the segmental motion. Then in the comonomer content range studied, the increase of the flow activation energy goes parallel with a decrease in the characteristic ratio. This result suggests that more parameters than only the stiffness of the chain modulate the thermal dependence of viscoelastic properties. A more refined study is necessary combining experiments with computer simulations in order to elucidate these aspects. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
8.
R. K. Bayer T. A. Ezquerra H. G. Zachmann F. J. Baltá Calleja J. Martinez Salazar W. Meins R. E. Diekow P. Wiegel 《Journal of Materials Science》1988,23(2):475-480
In Part 1 and Part 2 of this paper the preparation of linear polyethylene (PE)-carbon black processed composites with conducting electrical properties was examined by means of elongation flow injection moulding. Mould geometry was optimized in the form of oriented double-armed bars so as to give enhanced mechanical properties combined with a high degree of electrical homogeneity. The present paper deals with composites using a high molecular weight PE matrix. It is shown that the injection-moulded composite material exhibits not only a lower percolation threshold, c, than the conventionally pressure-moulded isotropic sample, but also conductivities two to three orders of magnitude larger than the latter. The radial and axial conductivity profiles, for concentrations well above c, are discussed in the light of the molecular orientation variations across the bars as determined by birefringence. A segregation of primary filler particles, during flow-induced orientation, into axial channels has been shown to explain the enhancement of conductivity detected in the injected mouldings. In addition, for filler concentrations near 7%, -profile analysis indicates the development of a uniform conductive-stiff inner cylinder, several millimetres wide, homogeneously extending along the full length of the injected material. 相似文献
9.
Iván González Sergio Salazar Rogelio Lozano 《Journal of Intelligent and Robotic Systems》2014,73(1-4):137-155
Nowadays, the chattering problem in sliding mode control is one of the most important points to consider in real-time applications. To address this problem, a real-time robust altitude control scheme is proposed for the efficient performance of a Quad-rotor aircraft system using a continuous sliding mode control. The sensing of altitude measurement sensing is performed by a pressure sensor in order to obtain a robust altitude control of the vehicle in hovering mode both indoor and outdoor. The altitude measurement has the advantage of introducing this state information directly in the closed loop control which should be very useful for achieving robust stabilization of the altitude control. Accordingly, we propose a sliding mode control strategy without chattering. The sliding mode control proposed removes the chattering phenomenon by replacing a sign function with a high-slope saturation function. The control algorithm is derived from the Lyapunov stability theorem. Moreover, we have assumed that the actuators are able to respond quickly and accurately and we have not enforced limits on the control signals for a real-time application. Finally, to verify the satisfactory performance of proposed nonlinear control law, several simulations and experimental results of the Chattering-free sliding mode control for the Quad-rotor aircraft in the presence of bounded disturbances are presented. 相似文献
10.
Hipolito Aguilar-Sierra Gerardo Flores Sergio Salazar Rogelio Lozano 《Journal of Intelligent and Robotic Systems》2014,73(1-4):455-468
This work addresses the problem of fault detection and diagnosis (FDD) for a quad-rotor mini air vehicle (MAV). Actuator faults are considered on this paper. The basic idea behind the proposed method is to estimate the faults signals using the extended state observers theory. To estimate the faults, a polynomial observer (Aguilar et al. 2011; Mata-Machuca et al., Commun Nonlinear Sci Numer Simul 15(12):4114–4130, 2010, BioSystems 100(1):65–69, 2010) is presented by using the available measurements and know inputs of the system. In order to investigate the diagnosability properties of the system, a differential algebra approach is proposed (Cruz-Victoria et al., J Frankl Inst 345(2):102–118, 2008; and Martinez-Guerra and Diop, IEE P-Contr Theor Ap 151(1):130–135, 2004). The effectiveness of the methodology is illustrated by means of numerical simulations. 相似文献