全文获取类型
收费全文 | 30418篇 |
免费 | 2832篇 |
国内免费 | 1494篇 |
学科分类
工业技术 | 34744篇 |
出版年
2024年 | 101篇 |
2023年 | 554篇 |
2022年 | 969篇 |
2021年 | 1461篇 |
2020年 | 1052篇 |
2019年 | 865篇 |
2018年 | 927篇 |
2017年 | 1025篇 |
2016年 | 939篇 |
2015年 | 1184篇 |
2014年 | 1561篇 |
2013年 | 1807篇 |
2012年 | 2042篇 |
2011年 | 2171篇 |
2010年 | 2012篇 |
2009年 | 1906篇 |
2008年 | 1752篇 |
2007年 | 1660篇 |
2006年 | 1601篇 |
2005年 | 1352篇 |
2004年 | 900篇 |
2003年 | 842篇 |
2002年 | 827篇 |
2001年 | 751篇 |
2000年 | 677篇 |
1999年 | 701篇 |
1998年 | 499篇 |
1997年 | 477篇 |
1996年 | 478篇 |
1995年 | 375篇 |
1994年 | 312篇 |
1993年 | 209篇 |
1992年 | 161篇 |
1991年 | 112篇 |
1990年 | 83篇 |
1989年 | 79篇 |
1988年 | 64篇 |
1987年 | 40篇 |
1986年 | 25篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1977年 | 4篇 |
1962年 | 42篇 |
1961年 | 39篇 |
1960年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 466 毫秒
91.
研究了铁钴钒软磁合金的铁芯损耗,发现铁芯损耗谱具有分形结构。讨论了带材厚度和磁感应强度对分形维数Df的影响。 相似文献
92.
93.
Ye. L. Stolov 《Journal of Electronic Testing》1993,4(3):283-283
Let a circuit havem outputs,m>1. There are two ways to test this circuit by means of a signature analyzer: use a single input analyzer for each output or use anm-input analyzer to test all outputs simultaneously. The main goal of this letter is to demonstrate that for fault output sequences with small multiplicity of errors and long length the second approach is more effective. 相似文献
94.
A damage identification technique for CF/EP composite laminates using distributed piezoelectric transducers 总被引:8,自引:0,他引:8
In this study, a damage identification approach was developed for carbon fibre/epoxy composite laminates with localized internal delamination. Propagation of the Lamb wave in laminates and its interaction with the delamination were examined. The fundamental symmetric Lamb wave mode, S0, and the lowest order shear wave mode, S0′, were chosen to predict damage location. A real-time active diagnosis system was therefore established. This technique uses distributed piezoelectric transducers to generate and monitor the ultrasonic Lamb wave with narrowband frequency. The two-way switches were employed to minimize the number of transducers. A signal-processing scheme based on the time–frequency spectrographic analysis was utilised to extract useful diagnostic information. Also, an optimal identification method was applied on damage searching procedure to reduce errors and obtain the diagnostic results promptly. Experiments were conducted on [0/−45/45/90]s CF/EP laminates to verify this diagnosis system. The results obtained show that satisfactory detection accuracy could be achieved. 相似文献
95.
运用电子显微分析和波谱分析等方法对GH2027合金的第二相进行了研究,结果表明,合金晶界相主要是片状M6C和薄膜状M23C6,经波纹图样测得其错配度约为3%,晶内M6C和M23 相似文献
96.
97.
泥浆制备中工艺改造的研究 总被引:1,自引:0,他引:1
根据室条件下粉磨试验结果,发现球磨过程中筛上料变化存在的突变范围,提出两次加料一次加水可改变泥浆颗粒分布,并找出适宜的加料种类与时间。另外给予测粒度分布提供了宝贵的试验基础数据。 相似文献
98.
99.
2001年浙江省率先利用市场机制配置水资源,经过近6年的实践,已经积累了一些数据,取得了较好的成效。为此,利用浙江省三个县(市)水资源开发权市场拍卖价格,来研究水资源开发权转让价格与相关要素之间的相关性和进行线性回归分析。通过分析,验证了水权出让价格与各有关因素之间的关系,同时指明了水资源市场化配置的良好态势。 相似文献
100.
A model of a human neural knowledge processing system is presented that suggests the following. First, an entity in the outside world lends to be locally encoded in neural networks so that the conceptual information structure is mirrored in its physical implementation. Second, the knowledge of problem solving is implemented in a quite implicit way in the internal structure of the neural network (a functional group of associated hidden neurons and their connections to entity neurons) not in individual neurons or connections. Third, the knowledge system is organized and implemented in a modular fashion in neural networks according to the local specialization of problem solving where a module of neural network implements an inter-related group of knowledge such as a schema, and different modules have similar processing mechanisms, but differ in their input and output patterns. A neural network module can be tuned just as a schema structure can be adapted for changing environments. Three experiments were conducted to try to validate the suggested cognitive engineering based knowledge structure in neural networks through computer simulation. The experiments, which were based on a task of modulo arithmetic, provided some insights into the plausibility of the suggested model of a neural knowledge processing system. 相似文献