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1.
Song  Tian-Yi  Qu  Xing-Yu  Pan  Zhu  Xiang  Kai  Zhou  Hongyuan 《Fire Technology》2022,58(5):2727-2754

This paper presents an experimental investigation on geopolymeric recycled aggregate concrete filled steel tubular (GRACFST) columns in fire. A total of 12 specimens were tested, including 6 circular columns and 6 square columns subjected to combined fire and loading. The test parameters include: (a) cross-section type (circular and square); (b) column load ratio (0.3, 0.4 and 0.6); and (c) fire scenario (all around fire exposure and two surfaces fire exposure). The failure mode, temperature development, deformation development and fire resistance of GRACFST columns were obtained and discussed. Finally, the fire resistance design method for conventional CFST columns proposed in Eurocode 4 was used to predict the ultimate cross sectional load bearing capacity of the GRACFST column at a specified fire exposure time, and the comparison between the prediction and the test results reported in this paper indicated that the Eurocode 4 method gave an overestimation to the GRACFST column. To improve the prediction accuracy, suitable material models for the passively confined GRAC in CFST columns should be developed in the future research.

  相似文献   
2.
Liu  Yu  Li  Bo  Wu  Chuanping  Chen  Baohui  Pan  Bichen 《Fire Technology》2022,58(5):3167-3190
Fire Technology - With 110 kV oil-immersed transformer as the platform, in this paper, we build a full-scale test platform covering 6 fire extinguishing (fire control) methods and different...  相似文献   
3.
This work discusses the results from tests conducted to investigate the uniaxial compression and creep behavior of red sandstone. An original untreated sample and an 800°C treated sample were selected to carry out the experiments. High temperature had an obvious influence on the mechanical properties of the red sandstone. The relationship between creep strain and instantaneous strain, as well as the instantaneous deformation modulus and creep viscosity coefficient, was analyzed. High temperature reduced the ability of the red sandstone to resist instantaneous deformation and creep deformation. Acoustic emission (AE) technology was also used in the loading process of uniaxial compression and creep tests, providing a powerful means for damage evolutionary analysis of the red sandstone.  相似文献   
4.
Just-in-time defect prediction can remind software developers and managers to verify and fix bugs at the moment they appeared, thus improving the effectiveness and validity of bug fixing. Existing studies mainly focus on just-in-time prediction for software files (JIT-F). JIT-F is a binary classification problem, which classifies (hence predicts) a file change as buggy or clean. This article provides a detailed analysis of just-in-time defect prediction for software hunks (JIT-H), which predicts bugs at a finer level of granularity, and hence further improves the efficiency of bug fixing. Classification is performed using the ensemble technique of bagging—aggregated combinations of random under sampling plus multiple classifiers (J48 and Random Forest). An empirical study with 10 open source projects was conducted to validate the effectiveness of JIT-H. Experimental results show that JIT-H is effective at predicting defects in software hunk changes. Compared with JIT-F, JIT-H is more cost effective. Additionally, analysis on the change features indicates that Text Vector features and hunk change level features are of more importance than features in other groups and levels.  相似文献   
5.
基于130 nm RF CMOS工艺,提出了一种可实现上/下双向变频功能的K波段有源混频器.当收发机工作于接收模式时,双向混频器执行下变频功能,将低噪放大器放大后的射频信号转换为中频信号;当收发机工作于发射模式时,双向混频器则实现上变频功能,将输入的基带信号转换为射频信号并输出至功率放大器.后仿真结果表明,在0 dBm的本振驱动下,混频器工作于上变频模式时的转换增益、噪声系数、输出1 dB压缩点在23~25 GHz范围内分别为-1.1~-0.4 dB、12.9~3.3 dB、-8.2 dBm@24 GHz;工作于下变频工作模式时的转换增益、噪声系数、输入1 dB压缩点在23~25 GHz范围内分别为2.4~3.4 dB、15.2~15.6 dB、-3.6 dBm@24 GHz.混频器芯片面积为0.6 mm2;在1.5V供电电压下,消耗功率12 mW.  相似文献   
6.
总结了近年来国内外废铅蓄电池回收的工艺特点,重点对铅膏湿法脱硫工艺及利用技术进行了综述,整体分为固-液、固-固两大脱硫技术体系,对比分析了现有技术特色与不足;从湿法预脱硫反应机理及其模型评述了湿法脱硫工艺的关键控制因素,探讨了脱硫过程中由产物层包覆引起的反应不彻底的问题;针对此问题,分析并且肯定了剪切、碰撞、研磨等机械强化方式对传质过程的促进作用,在此基础上,提出了边磨边浸出式强化脱硫的工艺发展方向。  相似文献   
7.
La2Ce2O7(LC) 和 LaMgAl11O19(LMA) 是两种新型热障涂层材料。 LC 具有优良的热物理及抗腐蚀性能, 但 其断裂韧性差。 LMA 具有良好的综合性能, 特别是力学性能优良。 基于复合材料设计理念, 为充分利用 LC 和 LMA 的优势, 本文探究了制备 LMA-LC 双相复合陶瓷的可行性。 采用高温固相法合成了 LMA 和 LC 粉末, 重 点研究了 LMA 和 LC 的高温稳定性, 初步研究了 LMA-LC 复合陶瓷块材的力学性能。 结果表明: LMA 和 LC 在 高温下发生了化学反应, 反应程度随温度升高而加剧, 主要反应产物为 LaAlO3, 其在低温下的铁弹性可能是复 合陶瓷在室温下具有良好力学性能的原因。  相似文献   
8.
福岛核事故发生以后,全厂断电事故成为了关注的热点。为了研究核电厂在全厂断电事故后的系统响应,文章采用系统分析程序针对非能动核电厂的系统、设备建立系统级模型,并开展计算分析。获得了主回路系统、安全系统关键参数的瞬态响应,得出如下结论:全厂断电事故后,非能动核电厂依靠蒸汽发生器(SteamGenerator,SG)和非能动余热排出系统(PassiveResidualHeat Removal system,PRHR)能够及时带出堆芯衰变热;PRHR启动的早晚影响SG二次侧冷却剂进行堆芯余热的带出,但对反应堆冷却能力的影响并不大;堆芯补水箱(CoreMakeupTanks,CMT)向主回路注入冷却剂的质量和速率对主回路温度、压力、稳压器液位的影响很大,可考虑调节CMT注入管线的阻力,使CMT注入流量在合理的水平,防止稳压器发生满溢。  相似文献   
9.
Verifiable secret sharing mainly solves the cheating behavior between malicious participants and the ground control center in the satellite network. The verification stage can verify the effectiveness of secret shares issued by the ground control center to each participant and verify the effectiveness of secret shares shown by participants. We use a lot of difficult assumptions based on mathematical problems in the verification stage, such as solving the difficult problem of the discrete logarithm, large integer prime factorization, and so on. Compared with other verifiable secret sharing schemes designed for difficult problems under the same security, the verifiable secret sharing scheme based on the Elliptic Curve Cryptography (ECC) system has the advantages of less computational overhead and shorter key. At present, the binary polynomial is a single secret scheme and cannot provide effective verification. Therefore, based on a Protected Verifiable Synchronous Multi Secret Sharing (PVS-MSS) scheme, this paper is designed based on bivariate asymmetric polynomials. The advanced verifiable attribute is introduced into the Protected Secret Sharing (PSS) scheme. This paper extends the protected synchronous multi-secret sharing scheme based on bivariate polynomial design. The ECC system constructs the security channel between the ground control center and participants and constructs the verification algorithm. Through the verification algorithm, any participant can verify the consistency and effectiveness of the secret shadow and secret share received from other participants or presented by the secret distribution center. Therefore, no additional key agreement protocol is required; participants do not need to negotiate the session key for encryption; the secret share polynomial can generate the session key between participants and speed up the secret reconstruction process. The verification stage has lower computational complexity than the verifiable scheme constructed by Rivest Shamir Adleman (RSA) and other encryption methods. Chinese Remainder Theorem (CRT) is used to update the secret shadow. The secret shadow does not need to be updated with the change of the scheme shared secret, and the public value update efficiency is higher. Reduce the complexity of sharing secret updates in a synchronous multi-secret sharing scheme.  相似文献   
10.
目的 针对金属棒料精密下料过程中坯料断面质量差的问题,提出一种新型低应力下料致裂方法。方法 利用有限元数值模拟构建低应力致裂可控旋弯下料三维有限元模型,模拟下料过程,分析缺口张角参数对下料效率的影响,并根据数值模拟结果进行相应的下料试验。结果 当缺口张角为对称45o时,缺口根部应力集中效应最为显著,坯料断面质量较好,同时下料效率较高。结论 使用新型低应力下料致裂方法能够在提高下料效率的同时保证较好的坯料断面质量,且数值模拟结果与实验结果有较高的一致性。  相似文献   
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