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排序方式: 共有1497条查询结果,搜索用时 15 毫秒
61.
随着"攻深找盲"战略的实施,一些隐伏于复杂地质条件下的磁异常急需验证,海城市牛庄地区磁异常,上部第四系覆盖层厚度达几百米,几十年来因施工难度太大都无法验证。依据目前单一岩心钻探施工技术,很难完成钻孔施工任务。通过对上部覆盖层,采用不取芯钻进工艺,较好地解决了上部复杂地层的施工难题,经过几个磁异常区的实践,都顺利地完成了钻孔施工任务。 相似文献
62.
S.D. Supekar A.F. Clarens D.A. Stephenson S.J. Skerlos 《Journal of Materials Processing Technology》2012,212(12):2652-2658
This paper investigates the cooling and lubrication properties of supercritical carbon dioxide (scCO2) sprays as potential substitutes for aqueous emulsions and straight oils used in the metalworking industry today. Sprays of rapidly expanding scCO2 act to cool and lubricate machining and forming processes by delivering a mixture of dry ice and lubricant deep into the cutting/forming zone. In this work, experiments with turning, milling, drilling, thread cutting, and thread forming were performed with scCO2 and other metalworking fluids (MWFs) to evaluate their relative performance with respect to tool wear and machining torque. Observations reveal that scCO2–MWFs are more effective in removing heat from the tool-workpiece interface than conventionally delivered (flood) aqueous MWFs as well as other gas-based MWF sprays. In addition, scCO2–MWFs delivered in lubricant-expanded phase, where scCO2 is used to increase volume of lubricant in the spray field, are shown to provide better lubricity than straight oils and oil-in-air minimum quantity lubrication (MQL) sprays. As a result, scCO2–MWFs can reduce tool wear and improve machining productivity in a wide range of manufacturing operations leading to appreciable improvements in the economics of manufacturing. Also given that CO2 is a recovered waste gas that is non-toxic, scCO2–MWFs can improve the environmental and worker health performance of manufacturing operations. 相似文献
63.
With the wide propagation of cloud and mobile computing, screen content images (SCIs) have become more indispensable in our daily lives. Compared to natural scene images (NSIs), SCIs possess many particular characteristics, like mixed contents, extremely sharp edges, and text graphics. Consequently, more challenges occur in the feature extraction, which is used to reflect the distortion, during the quality assessment of SCIs. Recently, some convolutional neural network (CNN) models have been designed by automatically learning feature to evaluate the quality. In this paper, we develop a novel blind quality assessment method for SCIs via the CNN. First, compared with existing CNN-based methods, the proposed method avoids the disadvantage of training with image patches, and it is the pioneering attempt that takes the entire image as inputs. Second, instead of the image gray value, the original image is decomposed into two portions, i.e., the predicted and unpredicted portions, according to the internal generative mechanism (IGM) theory as the input of CNN. Through the CNN, all features of the image are learned automatically from beginning to end, and the network finally outputs the predicted score. Since existing SCI database is too small, to fully train the network, we collected 30000 SCIs and employed a high-accuracy full-reference quality assessment metric of SCI to compute scores as the training labels. Experimental results on SIQAD database demonstrate that the proposed method is comparable to reference-based SCI quality assessment metrics and is superior to the state-of-the-art NSI quality assessment metrics. 相似文献
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66.
TD-LTE系统是纯IP网络,话音解决方案有单卡双待和话音回落两种,话音回落方案对终端电池的续航能力有较大提升。本文重点介绍TD-LTE系统话音回落的寻呼优化,针对寻呼过程中影响成功率的末端原因进行逐一分析定位,对失败占比较大的寻呼无响应、TAU、干扰进行了详细的分析并给出优化建议。 相似文献
67.
Mohammed Wanous Halim A. Boussabaine John Lewis 《Construction Management & Economics》2013,31(7):737-744
Despite the crucial importance of the ‘bid/no bid’ decision in the construction industry, it has been given little attention by researchers. This paper describes the development and testing of a novel bid/no bid model using the artificial neural network (ANN) technique. A back‐propagation network consisting of an input buffer with 18 input nodes, two hidden layers and one output node was developed. This model is based on the findings of a formal questionnaire through which key factors that affect the ‘bid/no bid’ decision were identified and ranked according to their importance to contractors operating in Syria. Data on 157 real‐life bidding situations in Syria were used in training. The model was tested on another 20 new projects. The model wrongly predicted the actual bid/no bid decision only in two projects (10%) of the test sample. This demonstrates a high accuracy of the proposed model and the viability of neural network as a powerful tool for modelling the bid/no bid decision‐making process. The model offers a simple and easy‐to‐use tool to help contractors consider the most influential bidding variables and to improve the consistency of the bid/no bid decision‐making process. Although the model is based on data from the Syrian construction industry, the methodology would suggest a much broader geographical applicability of the ANN technique on bid/no bid decisions. 相似文献
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69.
根据目前带式输送机有心轴托辊存在的问题,设计了一种用旋压工艺制造无心轴托辊的方法,研究了无心轴托辊管体的旋压成形过程,分析了其旋压过程中旋压温度、旋压轨迹、旋压道次、旋压速度和旋压变形力等工艺参数的影响。通过实验,给出了无心轴托辊管体的旋压过程中工艺参数的确定方法和数值。 相似文献
70.
固定帮无台阶非平面露天底开采境界 总被引:1,自引:0,他引:1
传统的露天矿开采境界为固定帮有台阶、露天底平面型。本文以四川会理岔河锡矿露天采场边坡为工程实例,介绍了露天矿无台阶边坡、非平面露天底开采境界的研究与设计过程和方法;论证了该种开采境界的适用条件及生产过程中应采取的安全措施;阐述了其技术经济效果。 相似文献