全文获取类型
收费全文 | 58655篇 |
免费 | 6262篇 |
国内免费 | 3612篇 |
专业分类
电工技术 | 5688篇 |
技术理论 | 3篇 |
综合类 | 5282篇 |
化学工业 | 4304篇 |
金属工艺 | 2724篇 |
机械仪表 | 4243篇 |
建筑科学 | 12157篇 |
矿业工程 | 2376篇 |
能源动力 | 1834篇 |
轻工业 | 2922篇 |
水利工程 | 3314篇 |
石油天然气 | 3938篇 |
武器工业 | 1352篇 |
无线电 | 4244篇 |
一般工业技术 | 5183篇 |
冶金工业 | 2146篇 |
原子能技术 | 631篇 |
自动化技术 | 6188篇 |
出版年
2024年 | 228篇 |
2023年 | 714篇 |
2022年 | 1511篇 |
2021年 | 1805篇 |
2020年 | 2119篇 |
2019年 | 1636篇 |
2018年 | 1564篇 |
2017年 | 2102篇 |
2016年 | 2278篇 |
2015年 | 2434篇 |
2014年 | 3845篇 |
2013年 | 3515篇 |
2012年 | 4578篇 |
2011年 | 4742篇 |
2010年 | 3582篇 |
2009年 | 3551篇 |
2008年 | 3204篇 |
2007年 | 3857篇 |
2006年 | 3496篇 |
2005年 | 3039篇 |
2004年 | 2515篇 |
2003年 | 2068篇 |
2002年 | 1778篇 |
2001年 | 1526篇 |
2000年 | 1226篇 |
1999年 | 1004篇 |
1998年 | 821篇 |
1997年 | 631篇 |
1996年 | 631篇 |
1995年 | 513篇 |
1994年 | 389篇 |
1993年 | 279篇 |
1992年 | 245篇 |
1991年 | 149篇 |
1990年 | 150篇 |
1989年 | 112篇 |
1988年 | 71篇 |
1987年 | 47篇 |
1986年 | 42篇 |
1985年 | 24篇 |
1984年 | 22篇 |
1980年 | 64篇 |
1979年 | 47篇 |
1965年 | 26篇 |
1964年 | 34篇 |
1960年 | 23篇 |
1959年 | 32篇 |
1956年 | 29篇 |
1955年 | 32篇 |
1954年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Scale and sludge from Bulalo geothermal field, Philippines, have been characterized by whole rock analysis, radioactivity counting, size analysis, light microscopy, scanning electron microscopy, and X-ray diffraction. Their leachability was assessed by regulatory leaching procedures and by sequential extraction. Both scale and sludge consisted mostly of oxides of Si, Al, and Fe with no radionuclides detected. The scale had 10% S content. Sulfides and silicates were important phases in both samples having size ranges from submicron to 2 mm. Geothermal soils at Bulalo have higher than normal soil levels of As, S, Cu, Cr, Zn, and Pb but regulatory leaching tests indicated that these elements are not released. However, the sequential extraction showed that As, Cu, and Zn were leachable under extreme conditions. 相似文献
102.
This paper presents a partial scan algorithm, calledPARES (PartialscanAlgorithm based onREduced Scan shift), for designing partial scan circuits. PARES is based on the reduced scan shift that has been previously proposed for generating short test sequences for full scan circuits. In the reduced scan shift method, one determines proch FFs must be controlled and observed for each test vector. According to the results of similar analysis, PARES selects these FFs that must be controlled or observed for a large number of test vectors, as scanned FFs. Short test sequences are generated by reducing scan shift operations using a static test compaction method. To minimize the loss of fault coverage, the order of test vectors is so determined that the unscanned FFs are in the state required by the next test vector. If there are any faults undetected yet by a test sequence derived from the test vectors, then PARES uses a sequential circuit test generator to detect the faults. Experimental results for ISCAS'89 benchmark circuits are given to demonstrate the effectiveness of PARES. 相似文献
103.
介绍了集随动系统在线监测与故障诊断于一体的智能系统。利用基于知识的诊断推理技术与神经网络技术相结合的方法构建了随动系统在线故障诊断专家系统,使得神经网络推理与基于符号的知识诊断控制、解释有机地结合起来,取长补短,大大提高了系统的工作效率和诊断可靠性。 相似文献
104.
Due to technology scaling and increasing clock frequency, problems due to noise effects lead to an increase in design/debugging efforts and a decrease in circuit performance. This paper addresses the problem of efficiently and accurately generating two-vector tests for crosstalk induced effects, such as pulses, signal speedup and slowdown, in digital combinational circuits. These noise effects can propagate through a circuit and create a logic error in a latch or at a primary output. We have developed a mixed-signal test generator, called XGEN, that incorporates classical static values as well as dynamic signals such as transitions and pulses, and timing information such as signal arrival times, rise/fall times, and gate delay. In this paper we first discuss the general framework of the test generation algorithm followed by computational results. Comparison of results with SPICE simulations confirms the accuracy of this approach. 相似文献
105.
A response to criticism of threshold plates for the study of color vision developed at the Mendeleev All-Russia Research Institute
of Metrology and published in 1994 is presented. The critics base their conclusions on colorimetric testing and the examination
of the plates.
In response to the article by M. V. Danilova and J. D. Mollon [4].
__________
Translated from Izmeritel’naya Tekhnika, No. 1, pp. 37–39, January, 2007. 相似文献
106.
利用单个圆柱螺旋扭转弹簧扭转原理,给出了一种用双向扭转圆柱组合螺旋弹簧实现扭矩测试的方法。根据扭转弹簧模型,给出了预紧力、加载的证明,并对实验结果进行分析;该结构用于扭矩测试系统既实用可靠,又简单易加工;降低了测试系统的成本,具有很高的实用价值。 相似文献
107.
108.
Carlos A. Felippa Bjrn Haugen Carmelo Militello 《International journal for numerical methods in engineering》1995,38(2):199-229
This paper starts a sequence of three articles that follow an unconventional approach in finite element research. The ultimate objective is to construct high-performance elements and element-level error estimators for those elements. The approach takes off from our previous work in high-performance elements and culminates with the development of finite element templates. The present paper concentrates on the patch test and evolved versions of the test that have played a key role in this research. Following a brief review of the historical roots, we present the Individual Element Test (IET) of Bergan and Hanssen in an expanded context that encompasses several important classes of new elements. The relationship of the IET to the multielement forms A, B and C of the patch test and to the single-element test are investigated. An important consequence of the IET application is that the element stiffness equations decompose naturally into basic and higher-order parts. The application of this decomposition to the “sanitization” of the non-convergent BCIZ element is described and verified with numerical experiments. Two sequel papers in preparation are subtitled ‘the algebraic approach’ and ‘element-level error estimation’. These apply the fundamental decomposition to the derivation of templates for specific mechanical elements and to the construction of element-level error estimators, respectively. 相似文献
109.
对安装于深圳赛意法微电子有限公司的TCN640制氮机进行了简介。该设备由Air Liquide Japan Ltd.(日本液空公司)总体设计、制造,国内技术人员消化改进工艺,具有设备配置先进,安装简单,安全高效,能耗低等优点,其产品氮气的纯度已超过了高纯氮的技术指标。 相似文献
110.
采用美国PDI公司开发的PDI-S软件,对不同缺陷基桩的反射波法低应变动测曲线进行数值模拟,对动测曲线的特征进行归纳与总结,以便在解释反射波法曲线时作为参考与借鉴,提高基桩质量检测的可靠度。 相似文献