全文获取类型
收费全文 | 14139篇 |
免费 | 1948篇 |
国内免费 | 1538篇 |
专业分类
电工技术 | 1392篇 |
综合类 | 1590篇 |
化学工业 | 818篇 |
金属工艺 | 384篇 |
机械仪表 | 383篇 |
建筑科学 | 1227篇 |
矿业工程 | 651篇 |
能源动力 | 403篇 |
轻工业 | 854篇 |
水利工程 | 755篇 |
石油天然气 | 2012篇 |
武器工业 | 131篇 |
无线电 | 1314篇 |
一般工业技术 | 820篇 |
冶金工业 | 1313篇 |
原子能技术 | 255篇 |
自动化技术 | 3323篇 |
出版年
2024年 | 81篇 |
2023年 | 252篇 |
2022年 | 576篇 |
2021年 | 638篇 |
2020年 | 566篇 |
2019年 | 474篇 |
2018年 | 436篇 |
2017年 | 484篇 |
2016年 | 536篇 |
2015年 | 592篇 |
2014年 | 893篇 |
2013年 | 816篇 |
2012年 | 1065篇 |
2011年 | 1214篇 |
2010年 | 931篇 |
2009年 | 924篇 |
2008年 | 893篇 |
2007年 | 1052篇 |
2006年 | 906篇 |
2005年 | 819篇 |
2004年 | 607篇 |
2003年 | 579篇 |
2002年 | 440篇 |
2001年 | 397篇 |
2000年 | 267篇 |
1999年 | 215篇 |
1998年 | 154篇 |
1997年 | 149篇 |
1996年 | 144篇 |
1995年 | 103篇 |
1994年 | 77篇 |
1993年 | 52篇 |
1992年 | 60篇 |
1991年 | 37篇 |
1990年 | 40篇 |
1989年 | 29篇 |
1988年 | 23篇 |
1987年 | 16篇 |
1986年 | 19篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1975年 | 2篇 |
1967年 | 2篇 |
1965年 | 3篇 |
1964年 | 7篇 |
1955年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
62.
Polyurethane acrylate anionomer (PUAA)/silica composite gels were prepared by the sol‐gel reaction of tetraethoxysilane (TEOS) and methacryloxypropyl trimethoxysilane (MPTS) incorporated to PUAA gels by using a swelling method. The formation and structure of composites were confirmed by FTIR, X‐ray diffraction, and SEM. As a result, we found that silica components in composites are located within the ionic domains of their gels and interacted with PUAA via hydrogen bonding. This drastically enhanced the mechanical properties of the composites. Mechanical properties are also improved by MPTS, because MPTS improves the dispersibility and adhesion of silica components in PUAA/silica composite gels. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2327–2334, 2002 相似文献
63.
64.
65.
在分步设计及大量计算的基础上,提出了一套考虑因素相对全面、指导 性强、易于操作的梯级水库电力实用优化调度图。该调度图继承了传统时历法调度图直观、 简明的优点,又具有其特有的优化功能。该方法以汛末蓄满水库为标准,确定典型来水过程 的预调度线和初始目标;以获得梯级电站最大长期调峰收益为目标,以变动目标水位控制为 核心,开发出调度图长系列操作通用程序模块,并以此模块作为寻优计算的手段。提出了水 库长期运行与短期实时调度有机结合,以及模拟计算、水位偏差最优反馈、来水预报、目标 水位寻优等多种实用处理技术。 相似文献
66.
67.
In this paper we report the evolution of the polar cluster like behavior with the incorporation of Ti4+ ion in BaZrO3 Ceramics. Dielectric behavior of BaZrxTi(1−x)O3 (x = 1.00, 0.95, 0.90, 0.85) ceramics is studied in the temperature range from 300 to 30 K. Polar cluster like behavior becomes more prominent with the increase in content of Ti4+ ion. The dielectric relaxation is analyzed by Vogel–Fulcher relation and Arrhenius law. Frequency dependence of dielectric constant and low loss tangent of these materials can be useful for the potential applications at low temperature. 相似文献
68.
For the past decade, the Taiwanese government has applied the policy of “North heavy, South light” to put more emphasis on development in northern Taiwan instead of the south. This has resulted in uneven development between the northern and southern regions, especially when introducing, developing, and supporting high technology and resource allocation in education. Industry clusters have become the centerpiece of economic development policy in many parts of the world. In this study, it is assumed that there are two categories of less-advantaged regions in Taiwan: (1) older industrialized regions dominated by labor-intensive/capital-intensive industries, and (2) industrial regions that have merged with potential high-technology small firms but still lack infrastructure. This study discusses the following points: (a) How do industrial clusters work in action? (b) What barriers do less-advantaged industrial clusters face? (c) What action strategies promote less-advantaged industrial clusters? 相似文献
69.
Ozgur Sinanoglu Ismet Bayraktaroglu Alex Orailoglu 《Journal of Electronic Testing》2003,19(4):457-467
Parallel test application helps reduce the otherwise considerable test times in SOCs; yet its applicability is limited by average and peak power considerations. The typical test vector loading techniques result in frequent transitions in the scan chain, which in turn reflect into significant levels of circuit switching unnecessarily. Judicious utilization of logic in the scan chain can help reduce transitions while loading the test vector needed. The transitions embedded in both test stimuli and the responses are handled through scan chain modifications consisting of logic gate insertion between scan cells as well as inversion of capture paths. No performance degradation ensues as these modifications have no impact on functional execution. To reduce average and peak power, we herein propose computationally efficient schemes that identify the location and the type of logic to be inserted. The experimental results confirm the significant reductions in test power possible under the proposed scheme. 相似文献
70.
In contrast to D. C. Zuroff, M. Mongrain, and D. A. Santor (2004), the current authors find the promissory note of dependency-sociotropy (DEP-SOC) and self-criticism-autonomy (SC-AUT) as a model of risk for depression to be in default. The authors propose reorganizing what has been cast as unitary effort into 3 distinct endeavors: a psychoanalytic clinical theory, development of a refined empirical model of risk for clinical depression, and research examining the effects of DEP-SOC and SC-AUT on interpersonal relationships in nonclinical samples. The authors identify some issues that need to be accommodated regardless of whether the assessment of Zuroff et al. (2004) or their own is accepted. DEP-SOC and SC-AUT are best construed as correlated, continuous dimensions. Future work also needs to accommodate depression as chronic recurrent condition, advances in developmental psychopathology, and more stringent criteria for positing a risk factor for clinical disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献