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951.
高效且准确地事件检测与跟踪是无线传感器网络研究的热点问题之一,现有的事件检测方案无法实现对形状不定的区域事件的检测与跟踪,为了解决这一问题,提出了一种改进的动态事件检测和跟踪方案.首先,该方案利用事件质心确定事件的具体位置,然后,考虑了节点的读数强度及该读数与事件质心的距离,提出节点动量概念以引导事件融合和分割检测.仿真实验结果表明,该方案可在各传感器结点中分布式运行,延迟低,能效高,在各种条件下均有很高的准确度.不论事件大小和事件数量如何,它始终可以确定正确的事件数量,给出正确的事件形状. 相似文献
952.
953.
Hyun Min Shim Joon Soo Lee Hong Yue Wang Seung Hak Choi Jeong Hoon Kim Hyung Taek Kim 《Korean Journal of Chemical Engineering》2007,24(3):537-541
The main purpose of the study was to develop a model using ASPEN and Excel simulation method to establish optimum CO2 separation process utilizing hollow fiber membrane modules to treat exhaust gas from LNG combustion. During the simulation,
optimum conditions of each CO2 separation scenario were determined while operating parameters of CO2 separation process were varied. The characteristics of hollow fibers membrane were assigned as 60 GPU of permeability and
25 of selectivity for the simulation. The simulation results illustrated that 4 stage connection of membrane module is required
in order to achieve over 99% of CO2 purity and 90% of recovery rate. The resulted optimum design and operation parameters throughout the simulation were also
correlated with the experimental data from the actual CO2 separation facility which has a capacity of 1,000 Nm3/day located in the Korea Research Institute of Chemical Technology. Throughout the simulation, the operating parameters of
minimum energy consumption were evaluated. Economic analysis of pilot scale of CO2 separation plant was done with the comparison of energy cost of CO2 recovery and equipment cost of the plant based on the simulation model.
This work was presented at the 6
th
Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006. 相似文献
954.
采用碳布层叠然后用化学气相渗方法制备了C/SiC复合材料,这种材料纤维与基体间的界面是决策材料力学行为的重要因素,带有热解碳作为界面层的C/SiC材料,在断裂进表现出大范围的脱粘,纤维与周围的基体不同发生断裂,有大量的纤维拨出,断口类似毛刷,无界央层材料表现为脆性平面断口,裂纹直接通过纤维和基体向前扩展,没有发生脱粘。 相似文献
955.
956.
Boolean functions with high nonlinearity, high resiliency and strict avalanche criterion (SAC) play an important role in the designs of conventional cryptographic systems. In this paper, a method is proposed to construct resilient Boolean functions on n variables (n even) satisfying SAC with nonlinearity 〉 2n-1 -2n/2. A large class of cryptographic Boolean functions that were not known earlier were obtained. 相似文献
957.
Jim D. Earls Jerry E. White Marvin L. Dettloff Marty J. Null 《Journal of Coatings Technology and Research》2004,1(3):243-245
Epoxidized 10-undecenoic acid triglyceride, an experimental seed oil derivative that has a terminal epoxy group on each of
the three acyl glyceride segments, has been found to have good reactivity with amine curatives and allows room temperature
cures to be obtained. Coatings based on epoxidized 10-undercenoic acid triglyceride have also shown excellent UV stability.
As an example, coatings samples placed in a QUVA chamber exhibit no loss in gloss after 3000 hr of a cycled exposure to high
intensity UV lamps and moisture at temperatures of 50–60°C. In comparison, coatings based on standard liquid epoxy resins
(LERs) and commercially available hydrogenated LERs lose gloss due to chalking/decomposition within 200–800 hr.
Presented at the 81 st Annual Meeting of the Federation of Societies for Coatings Technology, November 12–14, 2003, in Philadelphia,
PA. 相似文献
958.
The pulsed arc discharge to the surface of wastewater was applied to the degradation of a textile azo dye (Acid Red 27). A
high-voltage electrode (discharging electrode) was vertically placed above the surface of the wastewater while the wastewater
itself was grounded. The pulsed arc discharge occurred between the tip of the discharging electrode and the surface of the
wastewater, producing various oxidative species. Oxygen was used as the working gas instead of air to prevent nitrogen oxides
from forming. The effect of several parameters on the chromaticity and chemical oxygen demand (COD) removal was examined.
The results obtained showed that the chromaticity of the wastewater was completely removed by this process and the COD also
decreased significantly. It has been found that ozone formed in the gas phase mainly affects the removal of the dye. The contribution
of other effects such as ultraviolet light emission and OH radical formation during the arc discharge to the degradation of
the dye was found to be less than 15%. For the present reactor system, the optimum pH, pulse repetition rate and agitation
speed were found to be 3.0, 110 Hz and 300 rpm, respectively. 相似文献
959.
本文分别用主成分分析(PCA)、独立成分分析(ICA)以及线性鉴别分析(LDA)方法对图像进行特征抽取,采用支持向量机(SVM)算法进行人脸图像分类。通过在YALE人脸图像库上的实验结果验证表明,在多种特征抽取方法下的图像分类算法是有效的。 相似文献
960.
Crop residue,manure and fertilizer in dryland maize under reduced tillage in northern China: I grain yields and nutrient use efficiencies 总被引:4,自引:0,他引:4
Xiaobin Wang Dianxiong Cai Willem B. Hoogmoed Udo D. Perdok Oene Oenema 《Nutrient Cycling in Agroecosystems》2007,79(1):1-16
The rapidly increasing population and associated quest for food and feed in China has led to increased soil cultivation and
nitrogen (N) fertilizer use, and as a consequence to increased wind erosion and unbalanced crop nutrition. In the study presented
here, we explored the long-term effects of various combinations of maize stover, cattle manure and nitrogen (N) and phosphorus
(P) fertilizer applications on maize (Zea mays L.) yield and nutrient and water use efficiencies under reduced tillage practices. In a companion paper, we present the effects
on nutrient balances and soil fertility characteristics. The ongoing factorial field trial was conducted at Shouyang Dryland
Farming Experimental Station in northern China from 1993 onwards. The incomplete, determinant-optimal design comprised 12
treatments, including a control treatment, in duplicate. Grain yields and N, P, and potassium (K) uptakes and N, P and K use
efficiencies were greatly influenced by the amount of rain during the growing season (GSR), and by soil water at sowing (SWS).
There were highly significant interactions between GSR and added stover and manure, expressed in complex annual variations
in grain yield and N, P and K use efficiencies. Annual mean grain yields ranged from 3,000 kg ha−1 to 10,000 kg ha−1 and treatment mean yields from 4,500 kg ha−1 to 7,000 kg ha−1. Balanced combination of stover (3,000–6,000 kg), manure (1,500–6,000 kg) and N fertilizer (105 kg) gave the highest yield.
Stover and manure were important for supplying K, but the effects differed greatly between years. Overall mean N recovery
efficiency (NRE) ranged from 28% to 54%, depending on N source. NRE in wet years ranged from 50% to 90%. In conclusion, balanced
combinations of stover, manure and NP fertilizer gave the highest yield and NRE. Reduced tillage with adding stover and manure
in autumn prior to ploughing is effective in minimizing labor requirement and wind erosion. The potentials of split applications
of N fertilizer, targeted to the need of the growing crop (response farming), should be explored to further increase the N
use efficiency. 相似文献