全文获取类型
收费全文 | 464篇 |
免费 | 12篇 |
国内免费 | 14篇 |
专业分类
化学 | 81篇 |
晶体学 | 2篇 |
力学 | 5篇 |
综合类 | 1篇 |
数学 | 34篇 |
物理学 | 59篇 |
综合类 | 308篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 8篇 |
2015年 | 11篇 |
2014年 | 20篇 |
2013年 | 15篇 |
2012年 | 33篇 |
2011年 | 35篇 |
2010年 | 41篇 |
2009年 | 27篇 |
2008年 | 40篇 |
2007年 | 44篇 |
2006年 | 23篇 |
2005年 | 22篇 |
2004年 | 31篇 |
2003年 | 18篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有490条查询结果,搜索用时 93 毫秒
391.
392.
人民币国际化进程不断推进,对于中国国际话语权的提升,国际贸易摩擦的减缓,汇率风险的防范,意义非凡。本文从人民币国际化现状入手,通过分析我国经济特征出发,阐述了人民币国际化问题的必要性与可行性。 相似文献
393.
《信阳师范学院学报(自然科学版)》2016,(2):171-174
在希格斯三重态模型(HTM)的理论框架下,研究了带电希格斯玻色子对(H~±,H~(±±))与中性的希格斯玻色子h在国际线性对撞机(ILC)上的两个协同产生过程:e-e+→h H~+H~-和e-e+→hH~(++)H~(--),并计算了它们的产生截面,讨论了相关的标准模型背景.结果表明,在合理的参数空间内,这两个过程的产生截面分别达到几个fb和数十fb的量级,在未来的ILC实验上可能通过这些过程探测到HTM中带电标量粒子H~±和H~(±±)的信号. 相似文献
394.
Lithium fluoride thermoluminescent detectors (TLD) were used for cosmic radiation dosimetry already in early 1960s. Since that time they have been constantly applied in numerous space missions for personal dosimetry, area monitoring, phantom measurements and dosimetry for biological experiments. The relative efficiency of TLDs, defined as the ratio of their response to a given radiation and to a reference radiation, is not constant, but depends on ionization density. This raises a question about the relative efficiency of TLDs exposed to the complex cosmic radiation spectrum encountered in Earth's orbit, which consists of a variety of particles, including heavy ions, the spectrum of which covers an extremely broad energy range. The present work is an attempt to find an answer to this question.The particle energy spectra were calculated for realistic flight conditions of the International Space Station (ISS). The calculation of the Galactic Cosmic Ray (GCR) component was based on the input spectra generated with the DLR model for solar minimum (2009) and solar maximum (2000) conditions. Contributions of trapped protons were estimated based on the AP8 model for solar minimum and maximum taking into account the altitude variations of the ISS. The interactions of the primary particles with the ISS were simulated with GEANT4 using a shielding geometry derived from the mass distribution of the Columbus Laboratory of the ISS and several constant aluminum shieldings. The calculated spectra were convoluted with the experimental data on the relative TL efficiency measured for ions ranging from H to Xe at various particle accelerators for two commonly applied TL-materials, namely LiF:Mg,Ti and LiF:Mg,Cu,P.The results showed the differences in the average TL-efficiency for these two TL-materials. For LiF:Mg,Ti the relative efficiency is within a few percent from unity for any of the analyzed values of shielding, altitude and solar cycle conditions. This means that one can assume cosmic radiation doses measured in Low Earth Orbit (LEO) with LiF:Mg,Ti detectors to be correct within such uncertainty. LiF:Mg,Cu,P underestimates the cosmic radiation doses by more than 15% in all cases. Altitude and solar cycle were found to have a very weak influence on the TL efficiency. In contrast, the influence of shielding thickness is quite significant. The reason for this is a change of contributions of radiation field components: trapped protons dominate at low shielding (97% of dose at 1 g/cm2), but are negligible above 60 g/cm2, as well as changes within GCR spectrum (increase of dose due to lower LET secondaries for higher shielding). Shielding thickness affects both TLD types in different ways: the efficiency of LiF:Mg,Cu,P increases with increasing shielding thickness, while the efficiency of LiF:Mg,Ti shows some fluctuations, with a weak minimum for 60 g/cm2. The response ratio of these TLDs decreases monotonically with the shielding thickness and could be used as an indicator for the average shielding conditions in which the TLDs were exposed. 相似文献
395.
山东旅游职业学院作为走国际化办学道路的国内知名旅游院校,用独特的酒店课程培训模式培养并输出了一批批国际化实用优秀人才。本调查报告通过对参与酒店课程培训模式并且已经在海外实习工作的学生进行问卷调查,分析研究,得出结论,旨在更好的推动课程建设和培养更多的国际化旅游人才。 相似文献
396.
滨海新区被国家赋予"第三增长极"的历史使命,承载着推动我国经济发展方式的率先转型的重大责任。本文在对国家战略和国际科技园区发展趋势综合分析的基础上,为滨海高新区未来的发展提出了一种全新的定位和思路,即国际性的科技园区和响应技术与市场变化的全球性创新极。针对这样一种战略定位,文章最后为滨海高新区的建设提出了相应的发展思路和政策建议。 相似文献
397.
《Operations Research Letters》2023,51(1):105-110
When hit with an adverse shock, banks that do not comply with capital regulation sell risky assets to satisfy their solvency constraint. When financial markets are imperfectly competitive, this naturally gives rise to a GNEP. We consider a new framework with an arbitrary number of banks and assets, and show that Tarski's theorem can be used to prove the existence of a Nash equilibrium when markets are sufficiently competitive. We also prove the existence of ?-Nash equilibria. 相似文献
398.
Zhang Lin Carlos M. Vicente Gonçalves Ling Dai Hong-mei Lu Jian-hua Huang Hongchao Ji Dong-sheng Wang Lun-zhao Yi Yi-zeng Liang 《Analytica chimica acta》2014
Metabolic syndrome (MetS) is a constellation of the most dangerous heart attack risk factors: diabetes and raised fasting plasma glucose, abdominal obesity, high cholesterol and high blood pressure. Analysis and representation of the variances of metabolic profiles is urgently needed for early diagnosis and treatment of MetS. In current study, we proposed a metabolomics approach for analyzing MetS based on GC–MS profiling and random forest models. The serum samples from healthy controls and MetS patients were characterized by GC–MS. Then, random forest (RF) models were used to visually discriminate the serum changes in MetS based on these GC–MS profiles. Simultaneously, some informative metabolites or potential biomarkers were successfully discovered by means of variable importance ranking in random forest models. The metabolites such as 2-hydroxybutyric acid, inositol and d-glucose, were defined as potential biomarkers to diagnose the MetS. These results obtained by proposed method showed that the combining GC–MS profiling with random forest models was a useful approach to analyze metabolites variances and further screen the potential biomarkers for MetS diagnosis. 相似文献
399.
The measurement of radiation environmental parameters in space is essential to support radiation risk assessments for astronauts and establish a benchmark for space radiation models for present and future human space activities. The Japan Aerospace Exploration Agency (JAXA) is performing a continuous area radiation monitoring experiment using the “PAssive Dosimeters for Lifescience Experiments in Space” (PADLES) system inside the Japanese Experiment Module Kibo on board the International Space Station (ISS). The PADLES dosimeter consists of thermoluminescent dosimeters (TLDs) and CR-39 plastic nuclear track detectors (PNTDs). JAXA has run the Area PADLES experiment since the Kibo module was attached to the ISS in June 2008, using 17 dosimeters in fixed locations on the Pressurized Module (PM) and the Experiment Logistics Module-Pressurized Section (ELM-PS) of Kibo, which are replaced every 6 months or every Increment, respectively. For three monitoring periods, known as Area PADLES experiment series #1 to #3, of 301, 180, and 232 days in June 2008 to April 2010 over ISS Increments 17 to 22, the average absorbed dose (dose equivalent) rates of 12 positions in the PM of Kibo were 319 ± 30 μGy/day (618 ± 102 μSv/day), 276 ± 30 μGy/day (608 ± 94 μSv/day), and 293 ± 33 μGy/day (588 ± 84 μSv/day), respectively. The radiation measurement in the ELM-PS was conducted in only Area PADLES experiment series #3 from August 2009 to April 2010 (232 days) over ISS Increments 21 to 22, the average absorbed dose (dose equivalent) rates of 5 positions was 297 ± 28 μGy/day (661 ± 65 μSv/day). The directional dependence of the radiation field was also investigated by installing PADLES dosimeters located in the zenith of ELM-PS of Kibo. 相似文献
400.
柳蔚枝 《上饶师范学院学报》2006,26(2):36-39
联合国设立的前南国际法庭与卢旺达国际法庭,是国际刑事法院管辖权的早期实践,《国际刑事法院罗马规约》则是解决国际刑事法院管辖权如何与国内法院管辖权相协调的又一次尝试。从对前南和卢旺达两个法庭与国际刑事法院的管辖权的比较,分析国际性法院如何与国内法院的管辖权进行协调,以及何者更为优先的问题。 相似文献