全文获取类型
收费全文 | 963篇 |
免费 | 34篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 16篇 |
化学工业 | 235篇 |
金属工艺 | 33篇 |
机械仪表 | 11篇 |
建筑科学 | 9篇 |
能源动力 | 41篇 |
轻工业 | 121篇 |
水利工程 | 5篇 |
石油天然气 | 7篇 |
无线电 | 153篇 |
一般工业技术 | 155篇 |
冶金工业 | 97篇 |
原子能技术 | 6篇 |
自动化技术 | 109篇 |
出版年
2023年 | 7篇 |
2022年 | 16篇 |
2021年 | 26篇 |
2020年 | 20篇 |
2019年 | 19篇 |
2018年 | 22篇 |
2017年 | 22篇 |
2016年 | 26篇 |
2015年 | 16篇 |
2014年 | 37篇 |
2013年 | 71篇 |
2012年 | 41篇 |
2011年 | 42篇 |
2010年 | 36篇 |
2009年 | 43篇 |
2008年 | 48篇 |
2007年 | 42篇 |
2006年 | 26篇 |
2005年 | 22篇 |
2004年 | 13篇 |
2003年 | 24篇 |
2002年 | 13篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 21篇 |
1997年 | 26篇 |
1996年 | 29篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 28篇 |
1992年 | 17篇 |
1991年 | 16篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1968年 | 2篇 |
排序方式: 共有998条查询结果,搜索用时 15 毫秒
1.
Youngseok Lee Cheolmin Park Nagarajan Balaji Youn-Jung Lee Vinh Ai Dao 《Israel journal of chemistry》2015,55(10):1050-1063
Over the past few decades, crystalline silicon solar cells have been extensively studied due to their high efficiency, high reliability, and low cost. In addition, these types of cells lead the industry and account for more than half of the market. For the foreseeable future, Si will still be a critical material for photovoltaic devices in the solar cell industry. In this paper, we discuss key issues, cell concepts, and the status of recent high-efficiency crystalline silicon solar cells. 相似文献
2.
Entomopathogenic nematodes (Nematoda: Heterorhabditidae and Steinernematidae) are commonly used biological control agents of insects in cryptic habitats, but their potential for suppressing stored-product insects in these habitats has not been explored previously. Here, we provide data from the first step in a program to evaluate entomopathogenic nematodes in the genus Steinernema as biological control agents of stored-product pests by determining their pathogenicity to some of the major stored-product pest species. When evaluated against larvae, pupae and adults of six pest species (Plodia interpunctella, Ephestia kuehniella, Oryzaephilus surinamensis, Tenebrio molitor, Tribolium castaneum, and Trogoderma variabile), and the adults of two additional pest species (Sitophilus oryzae and Rhyzopertha dominica), Steinernema riobrave was either the most pathogenic or of similar pathogenicity compared to S. carpocapsae and S. feltiae. A dose of 10 infective juveniles of S. riobrave caused 80% or higher mortality against larvae of P. interpunctella, E. kuehniella, T. castaneum, and O. surinamensis, pupae of T. castaneum and T. molitor, and adults of T. molitor and the two moth species. All stages of Trogoderma variabile exhibited 70% or higher mortality. Adults of S. oryzae and R. dominica exhibited low susceptibility with 15% and 35% mortality, respectively. On the basis of these results, S. riobrave was selected for further evaluation under more field-like conditions. 相似文献
3.
M A Fennir J A Landry H S Ramaswamy V G S Raghavan 《The Journal of microwave power and electromagnetic energy》2003,38(3):189-196
This study investigates the effect of extraction methods on the color of date syrup and the potential use of microwave power for syrup processing. Sugar solutions were extracted from dates by boiling, soaking and blending. Color and sugar content of the extracted solutions were measured, and the percentage of sugar extracted form the total fruit sugar determined. Boiling was found to be the most efficient method of extraction whereby 74% of total samples sugar was extracted. In contrast, only 54.2% of fruit sugar was extracted by blending and 42% by soaking. In addition, solutions extracted by soaking and blending had a foaming problem in the subsequent concentration process. The extraction method had no effect on the product final color. The extracted solution was concentrated using two heating methods: conventional and microwave heating at a 600 W capacity and a frequency of 2450 MHz applied at three power levels: 10, 7, and 6. In the heating process, 180 minutes were needed to achieve a 77% degrees Brix using convective heating, while it took 81, 138, and 166 minutes of microwave heating at power level 10, 7, and 6, respectively to achieve the same concentration. Water activity of the syrup was measured within a sugar content range of 50 to 80% degrees Brix and the sugar concentration at which the product is shelf stable was determined at 76%. 相似文献
4.
J. Pujara M. A. Siddiqui Z. Liu P. Bjegovic S. S. Takagaki P. Y. Li S. Ramaswamy 《Drying Technology》2008,26(3):341-348
This is part II of a study reported earlier on a method to characterize the air flow and water removal characteristics during vacuum dewatering. This article presents experimental data and analysis of results from the use of a cyclically actuated vacuum dewatering device for removing moisture from wetted porous materials such as paper with the intermittent application of vacuum and accompanying air flow though the material. Results presented include sheet moisture content as a function of residence time and hence water removal rate under a variety of process conditions. Also, experimental results on air flow through the wet porous structure and hence the role and importance of air flow during vacuum dewatering are presented. Vacuum dewatering process conditions include exit solids content between 11 and 20% solid under applied vacuum conditions of 13.5 to 67.7 kPa (4 to 20 in. Hg). Regression analysis indicated that the exit sheet moisture content exhibited a nonlinear relationship with residence time with exit solids reaching a plateau after a certain residence time. Final moisture content correlated linearly with the average overall flow rate of air through the paper sample and the basis weight of the material. 相似文献
5.
M A Ramaswamy 《Sadhana》1987,10(3-4):445-458
The theoretical aerodynamic characteristics of a typical lifting symmetric supercritical airfoil demonstrating its superiority
over thenaca 0012 airfoil from which it was derived are presented in this paper. Further, limited experimental results confirming the
theoretical inference are also presented.
Invited Lecture given at the 3rd Asian Congress on Fluid Mechanics, held in Tokyo during 1–5 September, 1986 相似文献
6.
Sankaralingam K. Nagarajan R. Haiming Liu Changkyu Kim Jaehyuk Huh Burger D. Keckler S.W. Moore C. 《Micro, IEEE》2003,23(6):46-51
The Tera-op reliable intelligently adaptive processing system (TRIPS) architecture seeks to deliver system-level configurability to applications and runtime systems. It does so by employing the concept of polymorphism, which permits the runtime system to configure the hardware execution resources to match the mode of execution and demands of the compiler and application. 相似文献
7.
8.
Giboney K.S. Nagarajan R.L. Reynolds T.E. Allen S.T. Mirin R.P. Rodwell M.J.W. Bowers J.E. 《Photonics Technology Letters, IEEE》1995,7(4):412-414
Results of the first fabrication and measurement of travelling-wave photodetectors are reported. The devices have bandwidths as high as 172 GHz, the highest reported for a p-i-n photodetector, and bandwidth-efficiency products as large as 76 GHz, the largest reported for any photodetector without gain. Comparisons with vertically illuminated and waveguide photodetectors fabricated on the same wafer establish the superior performance of travelling-wave photodetectors. Microwave loss on the travelling-wave photodetector structure is identified as a bandwidth limitation 相似文献
9.
Hwar-Ching Ku Bala Ramaswamy 《International journal for numerical methods in engineering》1995,38(4):667-683
A new multi-grid (two-grid) pseudospectral element method has been carried out for solution of incompressible flow in terms of primitive variable formulation. The main objective of the proposed method is to apply the multi-grid technique solving the incompressible flow problems associated with three commonly encountered multi-grid environments. In domain decomposition terminology, it includes (I) partially overlapped subdomains, each of which has same types of grids; (II) partially overlapped subdomains, each of which has different types of grids; (III) local adaptive subdomains fully overlapped with the original computational domain (composite grids). The approach for flow problems, complex geometry or not, is to first divide the computational domain into a number of subdomains with the inter-overlapping area (partially or fully overlapped). In categories I and II, the fine-grid or coarse-grid subdomains can be defined by their representation, while in category III the fine-grid or coarse-grid subdomains are defined as usual. Next, implement the Schwarz Alternating Procedure (SAP) to exchange the data among subdomains, where the coarse-grid correction is used to remove the high frequency error that occurs when the data interpolation from the fine-grid subdomain to the coarse-grid subdomain is conducted. The strategy behind the coarse-grid correction is to adopt the operator of the divergence of velocity field, which intrinsically links the pressure equation, into this process. The solution of each subdomain can be efficiently solved by the direct (or iterative) eigenfunction expansion technique or preconditioned method with the least storage requirement, i.e. O(N2) in 2-D. Numerical results of (i) driven cavity flow (Re = 100,400) with Cartesian grids (category I) in each subdomain, (ii) driven cavity flow (Re = 3200) with local adaptive grids (category III) in each subdomain, and (iii) flow over a cylinder (Re = 250) with ‘O’ grids in one subdomain and Cartesian grids in another (category II) will be presented in the paper to account for the versatility of the proposed multi-grid method. 相似文献
10.
The second-order nonlinear coefficients measured in proton-exchanged LiNbO3 as a function of annealing time are discussed. Measurements of reflected second-harmonic power indicate that the second-order nonlinear coefficient d 33 is reduced to 60% of the bulk value as a result of proton exchange in pure benzoic acid. It is also shown that annealing restores the d -coefficients to almost the original value of the virgin crystal. For example, recovery to ~90% of the bulk value was obtained for a sample with a 0.3-μm-bulk proton-exchanged layer, annealed for 10 h at 350°C 相似文献