全文获取类型
收费全文 | 7562篇 |
免费 | 731篇 |
国内免费 | 270篇 |
专业分类
电工技术 | 302篇 |
综合类 | 408篇 |
化学工业 | 1549篇 |
金属工艺 | 335篇 |
机械仪表 | 355篇 |
建筑科学 | 438篇 |
矿业工程 | 161篇 |
能源动力 | 220篇 |
轻工业 | 756篇 |
水利工程 | 120篇 |
石油天然气 | 258篇 |
武器工业 | 41篇 |
无线电 | 1102篇 |
一般工业技术 | 1154篇 |
冶金工业 | 374篇 |
原子能技术 | 67篇 |
自动化技术 | 923篇 |
出版年
2024年 | 27篇 |
2023年 | 133篇 |
2022年 | 233篇 |
2021年 | 342篇 |
2020年 | 278篇 |
2019年 | 289篇 |
2018年 | 275篇 |
2017年 | 312篇 |
2016年 | 291篇 |
2015年 | 303篇 |
2014年 | 349篇 |
2013年 | 517篇 |
2012年 | 516篇 |
2011年 | 518篇 |
2010年 | 428篇 |
2009年 | 416篇 |
2008年 | 431篇 |
2007年 | 327篇 |
2006年 | 312篇 |
2005年 | 267篇 |
2004年 | 223篇 |
2003年 | 249篇 |
2002年 | 316篇 |
2001年 | 282篇 |
2000年 | 173篇 |
1999年 | 132篇 |
1998年 | 123篇 |
1997年 | 94篇 |
1996年 | 71篇 |
1995年 | 61篇 |
1994年 | 49篇 |
1993年 | 44篇 |
1992年 | 27篇 |
1991年 | 28篇 |
1990年 | 27篇 |
1989年 | 25篇 |
1988年 | 17篇 |
1987年 | 18篇 |
1986年 | 16篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1976年 | 3篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有8563条查询结果,搜索用时 0 毫秒
91.
陈思 《计算机光盘软件与应用》2010,(13)
本文就现今软件测试中存在的自动化检测过早退化及消亡的现象展开讨论,探讨其消亡原因以及对策,并就软件自动化测试技术的选择进行研究,从而实现应用软件自动化测试驶入"测试的快车道". 相似文献
92.
程思 《数字社区&智能家居》2009,(30)
论述了在医学院校中计算机文化基础教学中存在的一些问题,就如何提高教学效果、培养学生的能力,对大学计算机基础教学模式提出了一些切实可行的探索。从教学对象、教学方式等几个方面给出一些建议,力争提高计算机基础课程的教学质量和教学效果。 相似文献
94.
针对修正的PRI变换法无法分选重频参差雷达信号的缺点,提出了一种基于PRI谱的双门限雷达信号分选算法.该算法先对PRI谱设定双门限检测各个准PRI,再结合组合查看及序列搜索提取各个PRI.同时,构建了一种预分选、主分选结合的新型分选平台.预分选利用带有PowerPC的FPGA构架片上系统,完成对脉冲雷达信号的实时测量、AOA分类及数据存储;主分选采用DSP专职完成其他维参数的分选算法.谊分选新算法在保留抑制PRI子谐波优点的同时,对重频固定、抖动和参差的雷达脉冲信号都有较好的检测结果.视频信号源的大量测试表明,谊分选平台对普通雷达、PRI抖动和参差雷达、频率捷变雷达及一些特殊雷达均具有较好的分选能力. 相似文献
95.
介绍文本分类的研究背景、关键技术;总结经典文本分类方法;讨论目前新涌现的分本分类模型及面临的问题,并对文本分类趋势进行展望。 相似文献
96.
K. Levin Y. Zha R. J. Radtke Q. Si M. R. Norman H. -B. Schüttler 《Journal of Superconductivity》1994,7(3):563-570
We review the spin dynamics of the normal state of the cuprates with special emphasis on neutron data in both the YBa2Cu3O7– and La2–x
Sr
x
CuO4 systems. When realistic models of the Fermi surface shapes are incorporated, along with a moderate degree of spin fluctuations, we find good semiquantitative agreement with experiment for both cuprates. Building on the success of this Fermi-liquid-based scheme, we explore the implications ford-wave pairing from a number of vantage points. We conclude that our present experimental and theoretical understanding is inadequate to confirm or refute thed-wave scenario. 相似文献
97.
Two novel transition metal-doped tungsten bronze oxides, Pb2.15Li0.85Nb4.85Ti0.15O15 (PLNT) and Pb2.15Li0.55Nb4.85W0.15O15 (PLNW), are synthesized by high-temperature solid-state reactions. The Rietveld method using the high-resolution synchrotron radiation indicates that PLNT and PLNW crystallize in the orthorhombic polar noncentrosymmetric space group, Pmn21 (no. 31). As a class of tungsten bronze oxide, PLNT and PLNW retain a unique rigid framework composed of d0 transition metal cation (Ti4+ or W6+)-doped highly distorted NbO6 octahedra along with the subsequently generated Pb/LiO12 and PbO15 polyhedra. Interestingly, the d0 transition metal-doped tungsten bronzes, PLNT and PLNW, exhibit extremely large second-harmonic generation (SHG) responses of 56 and 67 × KH2PO4, respectively. The observed immeasurably strong SHG is mainly attributed to a net polarization originating from the alignment of highly distorted NbO6 octahedra with doped transition metals in the frameworks. It is believed that doping transition metal cations at the B-site of the tungsten bronze structures should be an innovative strategy to develop novel high-performance nonlinear optical materials. 相似文献
98.
Md. Moklesur Rahman Heung-Gyoon Ryu 《International Journal of Communication Systems》2023,36(8):e5475
In this paper, in order to improve the received signal strength (RSS) and signal quality, three arrays of electronically steerable parasitic array radiator (ESPAR) antennas are suggested for the ultra-high frequency (UHF) radio frequency identification (RFID) communication and sensing system applications. Instead of the single antenna, the array antennas have recently been widely used in many communication systems because of their peak gains, better radiation patterns, and higher radiation efficiency. Also, there are some important issues to use the antenna array like high data rates in wireless communication systems and to better understand the many targets or sensors. In this article, a wireless sensor network (WSN) is being investigated to overcome multipath fading and interference by antenna nulling technology that can be achieved through beam control ESPAR array antennas. The proposed ESPAR array antennas exhibit higher gains like 9.63, 10.2, and 12 dBi and proper radiation patterns from one array to another. Moreover, we investigate the mutual coupling effect on the performance of array antennas with different spacing (0.5λ, 0.75λ, λ) and configurations. It is found that the worst mutual coupling reduced by −28 to −34 dB for 2 × 2 array, −3 to −43 dB for 2 × 3 array, and finally −42 dB to −51 dB due to the antenna spacing from 0.5λ to λ. Thus, these suggested antennas could effectively be applied in the WSN communication systems, internet of things (IoT) networks, and massive wireless and backscatter communication systems. 相似文献
99.
Yan-kun Tang Qian Yang Xiao-fei Si Jin-kang Han Wei-wei Cao Ya-fei Li Fang Liu Xiaoyan Yao Ya Zhai 《Journal of Superconductivity and Novel Magnetism》2017,30(6):1527-1531
In this study, we report the results of an investigation into the sintering temperature dependence of magnetic and transport properties for GdBaCo2 O 5 + δ synthesized through a sol-gel method. The lowering of sintering temperature leads to the increase of oxygen content and the reduction of grain size. The increase of oxygen content results in the enhancement of magnetic interactions and the weakening of Coulomb repulsion effect, while the reduction of grain size improves the magnetoresistance effect. Metal-insulator transition accompanied with spin-state transition is observed in all samples. 相似文献
100.
Chung Yen Ang Si Yu Tan Cathleen Teh Jia Min Lee Mun Fei Eddy Wong Qiuyu Qu Li Qing Poh Menghuan Li Yuanyuan Zhang Vladimir Korzh Yanli Zhao 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(7)
Responsive nanomaterials have emerged as promising candidates as drug delivery vehicles in order to address biomedical diseases such as cancer. In this work, polymer‐based responsive nanoparticles prepared by a supramolecular approach are loaded with doxorubicin (DOX) for the cancer therapy. The nanoparticles contain disulfide bonds within the polymer network, allowing the release of the DOX payload in a reducing environment within the endoplasm of cancer cells. In addition, the loaded drug can also be released under acidic environment. In vitro anticancer studies using redox and pH dual responsive nanoparticles show excellent performance in inducing cell death and apoptosis. Zebrafish larvae treated with DOX‐loaded nanoparticles exhibit an improved viability as compared with the cases treated with free DOX by the end of a 3 d treatment. Confocal imaging is utilized to provide the daily assessment of tumor size on zebrafish larva models treated with DOX‐loaded nanoparticles, presenting sustainable reduction of tumor. This work demonstrates the development of functional nanoparticles with dual responsive properties for both in vitro and in vivo drug delivery in the cancer therapy. 相似文献