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51.
Thermal decomposition of powdered ammonium perchlorate (AP), polystyrene (PS) and propellant, catalysed by freshly-prepared CuCr2O4 and mixtures of CuCr2O4 and CuO, has been studied with a low concentration (1% by mass) of the catalysts. It appears that decomposition is increased due to heterogeneous catalysis. The kinetics of thermal decomposition of AP in the presence of CuCr2O4 in the orthorhombic region of AP have also been studied. 相似文献
52.
M. Lal 《International Journal of Engineering Science》1983,21(7):825-832
The present paper seeks to solve the problem of an elastic half space under torsion by a flat annular rigid stamp in the linear micropolar elasticity. The problem is reduced to the solution of a system of four Fredholm integral equations of the second kind in four unknown functions. An iterative solution of these integral equations has been obtained for for the case of simple rotation through a small angle and the corresponding classical results have been obtained. 相似文献
53.
The torsion of two finite, coaxial, circular cylinders of the same radius in perfect adhesion is considered. A part of the cylincrical surface of the system is held fixed against rotation while the remaining part is traction free. Torque is applied by means of a rigidly attached disc at one of the ends. The present mixed boundary value problem is formulated in terms of certain eigenfunctions pertaining to the composite domain. Appropriate form of the orthogonality of the eigenfunctions is given which is employed to reduce the dual series extending over the two regions to the solution of a Fredholm integral equation of the second kind. This is accomplished by means of an extension of the well known method of solving dual series due to Sneddon and Srivastav. Based upon the numerical solution of the integral equations, quantities of practical interest are graphically shown. 相似文献
54.
M. Lal 《Polymer International》1971,3(5):240-243
A computer technique for simulating configurational behaviour of chains, developed previously, was used to study the nature of the distribution of the magnitude of end-to-end vectors of excluded-volume chains constrained to two dimensions. The study revealed that the above distribution in the limit of infinite chain length deviates greatly from Gaussian behaviour and that the deviation is much greater than for three-dimensional chains. The probability distribution function A exp (—αR5.8) was derived. 相似文献
55.
This paper provides a demonstration of harnessing the power of the Internet to enable collaborative manufacturing in such a setup where the key components such as the human resource personnel and the manufacturing equipment are geographically separated. As part of the framework a platform independent and cost-effective means of remotely operating a 3-axis computer numerical control (CNC) drilling machine securely via the Internet has been developed. In addition, an infrastructure to allow remote manufacturers to collaborate on a product design as well to monitor the drilling process in real time is presented. The framework rests on sound security foundation implemented using technologies such as firewall, authentication modules and transport layer security (TLS) protocol to promote safe usage of the drilling machine. It is worth mentioning that the architectural design is generic and modular in nature and as such, any other genre of CNC machine such as milling and turning could be substituted in place of drilling with only machine-specific changes to the existing system. 相似文献
56.
Magan Lal Agrawal Rajesh Gupta Pramod R. Bhave 《Canadian Metallurgical Quarterly》2007,133(3):319-330
A water distribution network (WDN) is designed to meet time-varying demands with sufficient pressure, taking into consideration an appropriate demand during peak hours. Therefore, a network has inherent redundancy in the sense that under abnormal conditions such as those arising due to pipe breaks or pump failures, deficiency in supply during peak hours can be met through additional supply during off-peak periods. However, this necessitates a storage facility at the consumer end of the network, which is normally available in the form of a sump or an overhead tank in developing countries. Such a storage enables the consumer to store water during the off-peak period and then use it during the peak period. Reliability of a WDN is assessed herein considering nodal storage, and an iterative method is proposed for the optimal design of Level 1 redundant WDNs, i.e., networks that can sustain a single pipe failure without affecting consumer services either in part or in full. The method is illustrated through an example and the designs of a network with and without storage are compared. Provision of a nodal storage is found to reduce the total cost of the network. 相似文献
57.
58.
James R. Currie Ashok K. Batra Mohammad A. Alim Manmohan D. Aggarwal Ravindra B. Lal 《Journal of Materials Science: Materials in Electronics》2007,18(4):433-439
Polycrystalline SnO2 samples prepared in the laboratory were irradiated with 2 MeV He ions having doses of 3.62 × 1015 ion/cm2. The ac small-signal electrical data acquired for the polycrystalline SnO2 in the frequency (f) range 100 Hz ≤ f ≤ 1 MHz and temperature (T) range 26°C ≤ T ≤ 100°C revealed one semicircular relaxation in the impedance plane for the He implanted sample. However, two semicircular
relaxations were obtained in the same plane for the samples without He implantation. The He implantation indicated enhancement
in the donor density in the polycrystalline SnO2 as depicted via terminal conductance (or resistance).
An erratum to this article can be found at 相似文献
59.
This study deals with the assessment of the status of forest density in the Kangra district of Himachal Pradesh, western Himalaya. A classified forest map of the area with an accuracy of 88.17% was produced using the hybrid classification method in Erdas Imagine. An IRS 1D LISS III satellite image was used for mapping and classification. Forest density was calculated in the ArcGIS environment by overlaying a mesh of uniform resolution cells (500 m×500 m) on a classified forest map. The forest density value of each cell was later used for the preparation of forest density contours. The forest density output was verified by Normalized Difference Vegetation Index (NDVI) analyses. The forest cover of the study area was found to be 34.3%. Baroh area had the highest (45.87%) forest density and Baijnath (18.65%) the lowest. Central and western regions of the district showed high‐value forest density contours (>50%). The derived NDVI values were compared against the forest density classes for assessing the accuracy of the results obtained. A positive correlation (r = 0.99) between NDVI values and forest density confirms the accuracy of the results. 相似文献
60.
Chinmay Mallik Shyam Lal Manish Naja Duli Chand S. Venkataramani Hema Joshi 《International journal of remote sensing》2013,34(8):2749-2762
The combustion of fossil fuels (coal and petroleum products) constitutes a source of continuous release of anthropogenic SO2 into the atmosphere. Furthermore, natural sources such as volcanoes can inject large amounts of SO2 directly into the troposphere and sometimes even into the stratosphere. These event-based volcanic eruptions provide solitary opportunities to study the transport and transformation of atmospheric constituents. In this study, we present an episode of high SO2 concentration over northern India as a result of long-range transport from Africa using multiple satellite observations. Monthly averaged column SO2 values over the Indo-Gangetic Plain (IGP) were observed in the range of 0.6–0.9 Dobson units (DU) during November 2008 using observations from the Ozone Monitoring Instrument (OMI). These concentrations were conspicuously higher than the background concentrations (<0.3 DU) observed during 2005–2010 over this region. The columnar SO2 loadings were highest on 6 November over most of the IGP region and even exceeded 6 DU, a factor of 10–20 higher than background levels in some places. These enhanced SO2 levels were not reciprocated in satellite-derived NO2 or CO columns, indicating transport from a non-anthropogenic SO2 source. As most of the local aerosols over the IGP region occur below 3 km, a well-separated layer at 4–5 km was observed from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. Wind fields and back-trajectory analysis revealed a strong flow originating from the Dalaffilla volcanic eruption in Ethiopia during 4–6 November 2008. Although volcanic SO2 plumes have been extensively studied over many parts of Asia, Europe, and the USA, analysis of such events for the IGP region is being reported for the first time in this study. 相似文献