全文获取类型
收费全文 | 9958篇 |
免费 | 1384篇 |
国内免费 | 917篇 |
专业分类
化学 | 2584篇 |
晶体学 | 165篇 |
力学 | 1269篇 |
综合类 | 101篇 |
数学 | 1169篇 |
物理学 | 6971篇 |
出版年
2024年 | 7篇 |
2023年 | 62篇 |
2022年 | 143篇 |
2021年 | 172篇 |
2020年 | 196篇 |
2019年 | 150篇 |
2018年 | 156篇 |
2017年 | 321篇 |
2016年 | 365篇 |
2015年 | 311篇 |
2014年 | 554篇 |
2013年 | 643篇 |
2012年 | 585篇 |
2011年 | 648篇 |
2010年 | 513篇 |
2009年 | 641篇 |
2008年 | 715篇 |
2007年 | 725篇 |
2006年 | 587篇 |
2005年 | 588篇 |
2004年 | 548篇 |
2003年 | 453篇 |
2002年 | 404篇 |
2001年 | 379篇 |
2000年 | 330篇 |
1999年 | 289篇 |
1998年 | 264篇 |
1997年 | 256篇 |
1996年 | 180篇 |
1995年 | 168篇 |
1994年 | 121篇 |
1993年 | 128篇 |
1992年 | 119篇 |
1991年 | 80篇 |
1990年 | 65篇 |
1989年 | 60篇 |
1988年 | 58篇 |
1987年 | 49篇 |
1986年 | 33篇 |
1985年 | 32篇 |
1984年 | 30篇 |
1983年 | 18篇 |
1982年 | 24篇 |
1981年 | 19篇 |
1980年 | 6篇 |
1979年 | 23篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 724 毫秒
1.
The indentation technique is widely used in measuring the mechanical properties of soft matter at the microscale or nanoscale,but still faces challenges by these unique properties as well as the consequent strong surface adhesion, including the strong nonlinear effect, unclear judgment of the contact point, difficulties in estimating the contact area, and the risk of the indenter piercing the sample. Here we propose a two-step method to solve these problems: lay a hard film on a soft matter, and obtain the viscoelastic properties of this soft matter through the indentation response of this composite structure. We first establish a theoretical indentation model of the hard film-soft substrate system based on the theory of plates, elastic-viscoelastic correspondence principle and Boltzmann superposition principle. To verify the correctness of this method, we measure the mechanical properties of the methyl vinyl silicone rubber(MVSR) covered by a Cu nanofilm. Finally, we test the effectiveness and error sensitivity of this method with the finite element method(FEM). The results show that our method can accurately measure the mechanical properties of soft matter, while effectively circumventing the problems of the traditional indentation technique. 相似文献
2.
We numerically solve the time-dependent Ginzburg–Landau equations for two-gap superconductors using the finite-element technique. The real-time simulation shows that at low magnetic field, the vortices in small-size samples tend to form clusters or other disorder structures. When the sample size is large, stripes appear in the pattern. These results are in good agreement with the previous experimental observations of the intriguing anomalous vortex pattern, providing a reliable theoretical basis for the future applications of multi-gap superconductors. 相似文献
3.
Mariusz Marć Marek Tobiszewski Bożena Zabiegała Miguel de la Guardia Jacek Namieśnik 《Analytica chimica acta》2015
This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main drawback is the lack of standard procedures. Telemonitoring is another approach to air monitoring, which offers some interesting opportunities, such as ease of coverage of large or remote areas, constituting a complementary approach to traditional strategies; however, it requires huge costs. 相似文献
4.
5.
为探索油-气-水三相流持气率测量难题,该文开展了脉冲透射式超声传感器持气率测量动态实验研究。首先,利用超声传感器与光纤传感器组合,测取了油-气-水三相流中段塞流、混状流、泡状流的响应信号;其次,提取了超声脉冲信号的最大值序列来反映不同流型时超声传感器响应特性,同时,借助双头光纤传感器与相关测速法,计算得到了流体中气泡弦长序列;最后,结合流型与泡径信息,利用超声传感器测量了不同流型下持气率,并分析了不同流型持气率预测的误差来源,为其他油-气-水三相流持气率测量传感器设计提供了借鉴。 相似文献
6.
7.
8.
WANG Zhong HONG Haitao XIAO Hai SUN Changku MENG Yan YE Shenghua 《Chinese Journal of Lasers》1997,6(5):435-440
1.IntroductionAbsolutedistancemeasurementisfarfromanewtopic.However,itisstillafieldstimulatinggreatinterestsnowadaysduetoitSimportantroleinmanufacturingandassembly['J.SincethegreatsuccessachievedbyMichelsonandBenoitwhentheyfirstdevelopedaninterferometertodeterminethestandardmeterintermsofthemonochromaticredcadmiumline,theopticinterferometerhasbeenprovedtobeoneofthemostpreciseandefficientwayindisplacementmeasurementbecauseofitshighdiscriminationandsimplestructure.However,thetraditionalinterfe… 相似文献
9.
10.
一种利用电光效应测量微小转角的新方法 总被引:4,自引:1,他引:3
利用线性电光效应发展出一种新的、高准确度的微小转角测量法.根据W.L. She等人提出的线性电光效应耦合波理论,求得出射光强与入射光强比值(即出射率)对入射光方向的依赖曲线,利用该曲线,通过测量出射率可以确定入射光的方向.并根据此原理,设计了一套简单的装置,该装置可以测量出物体微小转角的变化量,同时测量范围及准确度都可通过外加电场和入射光波长加以调节.对此微小转角测量法作了理论分析,在LiNbO3器件上,得到测量范围大于3′,准确度为3.5″的设计结果. 相似文献