全文获取类型
收费全文 | 634篇 |
免费 | 40篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 137篇 |
金属工艺 | 10篇 |
机械仪表 | 13篇 |
建筑科学 | 12篇 |
矿业工程 | 1篇 |
能源动力 | 51篇 |
轻工业 | 38篇 |
水利工程 | 8篇 |
石油天然气 | 11篇 |
无线电 | 94篇 |
一般工业技术 | 156篇 |
冶金工业 | 26篇 |
原子能技术 | 8篇 |
自动化技术 | 108篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 15篇 |
2021年 | 31篇 |
2020年 | 20篇 |
2019年 | 11篇 |
2018年 | 25篇 |
2017年 | 22篇 |
2016年 | 28篇 |
2015年 | 16篇 |
2014年 | 43篇 |
2013年 | 46篇 |
2012年 | 32篇 |
2011年 | 49篇 |
2010年 | 40篇 |
2009年 | 32篇 |
2008年 | 32篇 |
2007年 | 35篇 |
2006年 | 24篇 |
2005年 | 18篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 14篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1969年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有678条查询结果,搜索用时 15 毫秒
1.
Abhijit Datta 《Cities》1985,2(1):72-75
Early in 1983 the Indian Planning Commission appointed four Task Forces on Housing and Urban Development to review existing urban policies and to recommend appropriate action starting from the Seventh Plan (1985–1989). The Task Forces covered four areas of major concern: (1) urban planning, (2) urban finance, (3) urban organizations, and (4) urban shelter. They submitted their reports by the end of 1983, and taken together these constitute the most significant review of urban policy ever undertaken in India. 1 The Task Forces had distinguished urban experts, both officials and academics, as members, with a common Member-Secretary from the Planning Commission. The common theme in all four reports is a plea for a decentralized and equitable approach towards urban development in the country. 相似文献
2.
Summary Theoretical and experimental analyses have been carried out for determining the injection condition below which the formation of air core does not take place in the course of flow of a time-independent power-law fluid through a swirl nozzle. Analytical solution lends one distinct value of generalized Reynolds number at the inlet to a nozzle below which the air core is not formed. Experiments reveal that there exist two limiting values of such generalized Reynolds number regarding the formation of air core in a nozzle. One value being the upper limit below which steady flow occurs without air core, the other one is the lower limit above which steady flow with fully developed air core persists. In between these two limiting values, there prevails a transition zone through which fully developed air core is set up within the nozzle. For all the nozzles, theoretical results are in fair agreement with the experimental values of upper limit of generalized Reynolds numbers with respect to steady flow without air core. Amongst all the pertinent independent geometrical parameters of a nozzle, the orifice-to-swirl chamber-diameter ratio has the remarkable influence on generalized Reynolds number describing the initiation of air core.Nomenclature
D
1
Swirl chamber diameter
-
D
2
Orifice diameter
-
D
s
Diameter of tangential entry ports
-
E
A non-dimensional parameter defined by Eq. (9)
-
E
R
A non-dimensional parameter defined by Eq. (25)
-
K
Flow consistency index
-
L
1
Length of the swirl chamber
-
n
Flow behaviour index
-
P
Static pressure inside the nozzle
-
P
b
Back-pressure of the nozzle
-
Q
Volume flow rate
-
R
Radius vector or longitudinal coordinate with respect to spherical coordinate system (Fig. 3)
-
R
1
Radius of the swirl chamber
-
R
2
Radius of the orifice
-
Generalized Reynolds number at the inlet to the nozzle
-
Limiting value of generalized Reynolds number describing initiation of air core
-
R
z
Radius at any section
-
r
Radial distance from the nozzle axis
-
r
a
Air core radius
-
u
Longitudinal component of velocity with respect to spherical coordinate system (Fig. 3)
-
V
r
Radial velocity component
-
V
z
Axial velocity component
-
V
Tangential velocity component
-
Tangential velocity at inlet to the nozzle
-
v
Component of velocity in the axial plane perpendicular toR (Fig. 3)
-
w
Component of velocity perpendicular to axial plane with respect to the spherical coordinate system (Fig. 3)
-
z
Distance along the nozzle axis from its inlet plane
-
Half of the spin chamber angle
-
Boundary layer thickness measured perpendicularly from the nozzle wall
- 2
Boundary layer thickness at the orifice
-
Angle, which a radius vector makes with the nozzle axis, in spherical coordinate system (Fig. 3)
-
Density of the fluid
-
Running coordinate in the azimuthal direction with respect to the cylindrical polar coordinate system as shown in Fig. 3
-
Circulation constant
With 8 Figures 相似文献
3.
The temporal scale effect of loading data on nitrate-nitrogen load computation was examined using outputs of watershed modeling tool Hydrologic Simulation Program-FORTRAN (HSPF) for the Amite River in Louisiana, USA. The daily nitrate-nitrogen concentrations simulated using the HSPF were employed first to obtain daily, weekly, bi-weekly, and monthly average data and then to develop load duration curves for the data with four different temporal scales. The duration curves exhibited high variability in the load estimated using daily data as compared with those based on bi-weekly and monthly data. According to daily data, the nitrate-nitrogen load in the winter was found to be 2,780 kg. The nitrate-nitrogen load decreased with increasing temporal (daily, weekly, bi-weekly, and monthly) scale (commonly used in water quality monitoring) of the data. The coefficient of variation, used to quantify the effect of temporal scale on the load, was found to be linearly and inversely correlated with the logarithm of the time scale. Based on the finding, empirical equations were proposed to extrapolate near real-time data for flow and nitrate-nitrogen, greatly simplifying nutrient monitoring and reducing the cost involved in water quality monitoring. 相似文献
4.
Abhijit P. Brahme Kaan Inal Raja K. Mishra Shigeo Saimoto 《Computational Materials Science》2011,50(10):2898-2908
This paper presents a crystal plasticity based finite element analysis employing the new microstructure-based strain hardening model recently presented by Saimoto and Van Houtte (2011) [7] to simulate formability and texture evolution in the commercial aluminum alloy 5754. Simulations are performed to compare the predictive capability of the new hardening model against the common work hardening models using a rate-dependent plasticity formulation. The parameters in the numerical models are calibrated using the X-ray data published by Iadicola et al. (2008) [9] for the aluminum sheet alloy 5754. The predictions of the model for balanced biaxial tension and in-plane plane-strain tests are compared against experimental observations presented in Iadicola et al. (2008) [9]. It is concluded that the new model provides the best predictions of the large strain behavior of Aluminum sheet alloy 5754 subjected to various strain paths. 相似文献
5.
Wireless Personal Communications - Miscellaneous issues related to wireless sensor networks (WSN) like clustering of sensor nodes, load balancing amongst the cluster heads, energy efficient... 相似文献
6.
Sayanti Ghosh Abhijit Bhowmick Sanjay Dhar Roy Sumit Kundu 《International Journal of Communication Systems》2023,36(18):e5615
An unmanned aerial vehicle (UAV)-assisted communication is a promising technique for enabling ground users in a non-functional area (NFA) or disaster area to communicate. All the base stations in the disaster area may be partially or fully damaged due to the natural calamity. Device-to-device (D2D) communication can be a viable solution for immediate connection between users in an NFA. We propose a UAV-assisted multi-hop D2D communication following a hybrid power-time switching (PTS) in this paper. Moreover, a D2D user of a cluster can communicate with another D2D user in a different cluster through UAVs. However, D2D users can harvest energy from their respective ad hoc energy stations and forward the information to the nearby D2D user following a hybrid PTS-based strategy. We propose a time frame for the same and show a node-based energy harvesting strategy. The expressions of outage probability, throughput, end-to-end energy consumption, and energy efficiency are developed for the Rician and Nakagami-m faded channel. The impact of several network parameters such as energy harvesting factor, energy harvesting efficiency, and fading parameter on the network performance is also indicated. 相似文献
7.
David J. Banner Emre Firlar Pavel Rehak Abhijit H. Phakatkar Tara Foroozan Jodi K. Osborn Lioudmila V. Sorokina Surya Narayanan Talia Tahseen Yusuf Baggia Petr Král Tolou Shokuhfar Reza Shahbazian-Yassar 《Advanced functional materials》2021,31(18):2007736
Calcium oxalate (CaOx) is the major phase in kidney stones and the primary calcium storage medium in plants. CaOx can form crystals with different lattice types, water contents, and crystal structures. However, the conditions and mechanisms leading to nucleation of particular CaOx crystals are unclear. Here, liquid-cell transmission electron microscopy and atomistic molecular dynamics simulations are used to study in situ CaOx nucleation at different conditions. The observations reveal that rhombohedral CaOx monohydrate (COM) can nucleate via a classical pathway, while square COM can nucleate via a non-classical multiphase pathway. Citrate, a kidney stone inhibitor, increases the solubility of calcium by forming calcium-citrate complexes and blocks oxalate ions from approaching calcium. The presence of multiple hydrated ionic species draws additional water molecules into nucleating CaOx dihydrate crystals. These findings reveal that by controlling the nucleation pathways one can determine the macroscale crystal structure, hydration state, and morphology of CaOx. 相似文献
8.
Ho Wai Wong-Lam 《电子产品世界》2006,(11):44-46
ExpressCard模块是由PCMCIA推出的一种更薄、更快、更轻的抽屉式插卡,用以取代现有的PC卡和CardBus模块,主要用于笔记本计算机后继市场中的功能性升级和扩展.同样,ExpressCard模块最初旨在服务于笔记本计算机后继市场(图1a). 相似文献
9.
Evolutionary computational techniques have been employed judiciously in various signal processing applications of late. In this paper, such an attempt has been made to design a low-pass linear-phase multiplier-less finite duration impulse response (FIR) filter using differential evolution (DE) algorithm. This particular evolutionary optimization technique has been explored to search the impulse response coefficients of the FIR filter in the form of sum of power of two (SPT) in order to avoid the multipliers during design process. The performance of the designed low-pass filter has been studied thoroughly in terms of its frequency characteristics and primitive requirement of fundamental hardware blocks. The superiority of our design has been ascertained over a number of existing techniques by various means. Finally, the proposed filter of different lengths has been implemented on a field programmable gate array (FPGA) chip for evaluating the competency of this work. The percentage improvement in hardware complexity produced by our design has also been computed and clearly listed in this paper for convenience. 相似文献
10.
Shreyas Sen Aritra Banerjee Vishwanath Natarajan Shyam Devarakond Hyun Choi Abhijit Chatterjee 《Journal of Electronic Testing》2012,28(4):405-419
Testing of Radio Frequency (RF) circuits for nonlinearity specifications generally requires the use of multiple test measurements thereby contributing to increased test cost. Prior RF test methods have suffered from significant test calibration effort (training for supervised learners) when using compact tests or from increased test time due to direct specification measurement. On the other hand, due to aggressive technology scaling, there are plenty of digital transistors available that can be used to simplify testing of Analog/Mixed-Signal (AMS) and RF devices. In this paper, an RF test methodology is developed that: (a) allows RF devices to be tested for several distortion specifications using distortion model fitting algorithms in test time comparable to what can be achieved using supervised learning techniques while retaining the accuracy of direct specification measurement, (b) allows multiple RF specifications to be determined concurrently from a single data acquisition and (c) allows digital-compatible testing/BIST to be performed using digital testers or on-chip built in self-test (BIST) circuitry. With regard to (a), a key benefit is that no training of supervised learning algorithm is necessary. The proposed method based on distortion model fitting is shown to give excellent results across common RF performance metrics while providing ~10× improvements in test time compared to previous methods. 相似文献