全文获取类型
收费全文 | 3110篇 |
免费 | 323篇 |
国内免费 | 79篇 |
专业分类
化学 | 1176篇 |
晶体学 | 3篇 |
力学 | 59篇 |
综合类 | 28篇 |
数学 | 1533篇 |
物理学 | 713篇 |
出版年
2023年 | 35篇 |
2022年 | 72篇 |
2021年 | 114篇 |
2020年 | 139篇 |
2019年 | 102篇 |
2018年 | 79篇 |
2017年 | 79篇 |
2016年 | 113篇 |
2015年 | 115篇 |
2014年 | 114篇 |
2013年 | 154篇 |
2012年 | 124篇 |
2011年 | 321篇 |
2010年 | 271篇 |
2009年 | 375篇 |
2008年 | 302篇 |
2007年 | 258篇 |
2006年 | 217篇 |
2005年 | 114篇 |
2004年 | 79篇 |
2003年 | 81篇 |
2002年 | 44篇 |
2001年 | 37篇 |
2000年 | 22篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 18篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 14篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有3512条查询结果,搜索用时 15 毫秒
1.
Particularly-shaped silver nanostructures are successfully applied in many scientific fields, such as nanotechnology, catalysis, (nano)engineering, optoelectronics, and sensing. In recent years, the production of shape-controlled silver-based nanostructures and the knowledge around this topic has grown significantly. Hence, on the basis of the most recent results reported in the literature, a critical analysis around the driving forces behind the synthesis of such nanostructures are proposed herein, pointing out the important role of surface-regulating agents in driving crystalline growth by favoring (or opposing) development along specific directions. Additionally, growth mechanisms of the different morphologies considered here are discussed in depth, and critical points highlighted. 相似文献
2.
在分析政府监管下医院间医疗信息分享特征的基础上,结合我国当前正在推行的医联体医院间信息分享运作模式,引入梅特卡夫定律并考虑患者评价的影响,分析了监管部门与医院各自的利益组成,建立了监管部门与医院两者之间的演化博弈模型,并采用复制动态方程研究了不同情形下医院间信息分享的演化博弈轨迹。研究表明,政府通过监管并建立激励惩罚机制等引导措施对医院最终达到的演化稳定态具有极大影响;降低医院主体信息分享的风险成本、规范提高医院分享信息的质量、引导患者增强对医院信息分享的关注、制定有吸引力和威慑力的奖惩政策,是促进医院医疗信息分享的关键。研究结果可为政府监管部门预测医院间的信息分享趋势和制定精准化政策以促进分享提供参考。 相似文献
3.
Huadong Yuan Prof. Jianwei Nai Dr. Yongjin Fang Gongxun Lu Prof. Xinyong Tao Prof. Xiong Wen Lou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):15973-15977
The growth of Li dendrites hinders the practical application of lithium metal anodes (LMAs). In this work, a hollow nanostructure, based on hierarchical MoS2 coated hollow carbon particles preloaded with sulfur (C@MoS2/S), was designed to modify the LMA. The C@MoS2 hollow nanostructures serve as a good scaffold for repeated Li plating/stripping. More importantly, the encapsulated sulfur could gradually release lithium polysulfides during the Li plating/stripping, acting as an effective additive to promote the formation of a mosaic solid electrolyte interphase layer embedded with crystalline hybrid lithium-based components. These two factors together effectively suppress the growth of Li dendrites. The as-modified LMA shows a high Coulombic efficiency of 98 % over 500 cycles at the current density of 1 mA cm−2. When matched with a LiFePO4 cathode, the assembled full cell displays a highly improved cycle life of 300 cycles, implying the feasibility of the proposed LMA. 相似文献
4.
5.
提出了一类新的相对性区域创新指数,并采用世界专利申请数据对其进行了具体计算.基于区域创新同经济发展水平之间的超线性关系,该指数消除了经济发展水平对创新能力的影响,可以实现对不同发展水平的经济体之间进行有效的创新能力横纵对比.该创新指数尽管极其简单,却揭示出一系列迥异于传统认知的现象,例如中国大陆地区的技术创新能力在1980年代就已经位居世界前列.采用该指数,不但可以在较高水平上解释世界各国的经济增长,还发现它同经济增长率之间的相关性存在一个20年的经济周期.这些结果显示,该指数作为一个单一性指标,以极小的数据依赖就实现了较高程度的解释性,不但重新定位了世界各经济体的创新能力,对深入理解创新同经济发展之间的关系提供了新的角度,而且暗示着这类相对性经济指标的发展潜力与应用空间. 相似文献
6.
Back Cover: Covalent Modification of Graphene Oxide with Carbazole Groups for Laser Protection (Chem. Eur. J. 12/2015) 下载免费PDF全文
7.
Dr. Esmail Doustkhah Prof. Dr. Jianjian Lin Prof. Dr. Sadegh Rostamnia Prof. Dr. Christophe Len Prof. Dr. Rafael Luque Prof. Dr. Xiliang Luo Prof. Dr. Yoshio Bando Prof. Dr. Kevin C.-W. Wu Dr. Jeonghun Kim Prof. Dr. Yusuke Yamauchi Dr. Yusuke Ide 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(7):1614-1635
Sulfonic acid based mesostructures (SAMs) have been developed in recent years and have important catalytic applications. The primary applications of these materials are in various organic synthesis reactions, such as multicomponent reactions, carbon–carbon bond couplings, protection reactions, and Fries and Beckman rearrangements. This review aims to provide an overview of the recent developments in the field of SAMs with a particular emphasis on the reaction scope and advantages of heterogeneous solid acid catalysts. 相似文献
8.
Loading of a Coordination Polymer Nanobelt on a Functional Carbon Fiber: A Feasible Strategy for Visible‐Light‐Active and Highly Efficient Coordination‐Polymer‐Based Photocatalysts 下载免费PDF全文
Prof. Dr. Xin‐Xin Xu Dr. Hong‐Yu Yang Dr. Zhen‐Yu Li Prof. Dr. Xiao‐Xia Liu Prof. Dr. Xiu‐Li Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3821-3830
To improve the photocatalytic properties of coordination polymers under irradiation in the visible‐light region, coordination polymer nanobelts (CPNB) were loaded on functional carbon fiber (FCF) through the use of a simple colloidal blending process. The resulting coordination polymer nanobelt loaded functional carbon fiber composite material (CPNB/FCF) exhibited dramatically improved photocatalytic activity for the degradation of rhodamine B (RhB) under visible‐light irradiation. Optical and electrochemical methods illustrated the enhanced photocatalytic activity of CPNB/FCF originated from high separation efficiency of photogenerated electrons and holes on the interface of CPNB and FCF, which was produced by the synergy effect between them. In the composite material, the role of FCF could be described as photosensitizer and good electron transporter. For FCF, the number of functional groups on its surface has a significant influence on the photocatalytic performance of the resulting CPNB/FCF composite material, and an ideal FCF carrier was obtained as a highly efficient CPNB/FCF photocatalyst. CPNB/FCF showed outstanding stability during the degradation of rhodamine B (RhB); thus, the material is suitable for use as a photocatalyst in the treatment of organic dyes in water. 相似文献
9.
Prof. Dr. Masaki Shimizu Sho Nagano Takumi Kinoshita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5162-5167
Fluorescence–phosphorescence dual-emissive compounds are valuable tools for ratiometric luminescence sensing. Herein, it is reported that 2,5-bis(phenylsulfonyl)- and 2,5-bis[bis(4-methoxyphenyl)phosphinyl]-1,4-disiloxybenzenes exhibit dual emission with emission peaks that were easily identified without performing time-gated measurement. The disiloxybenzenes in powder simultaneously fluoresced and phosphoresced at 358–374 and 457–470 nm, respectively, under vacuum. The intensity ratios of the phosphorescence/fluorescence maxima of the disiloxybenzenes in powder and in a thin film of poly(methyl methacrylate) were sensitive to temperature and molecular oxygen, respectively. The plots of the relative intensity versus temperature or partial pressure of molecular oxygen were well fitted with calibration curves defined by an exponential approximation with excellent correlation coefficients R2 (0.9708–0.9921), demonstrating the high potential of the disiloxybenzenes as precious metal-free probes applicable to ratiometric luminescence sensing. 相似文献
10.
Recent research has focused on increasing the evidentiary value of latent fingerprints through chemical analysis. Although researchers have optimized the use of organic and metal matrices for matrix‐assisted laser desorption/ionization‐mass spectrometry imaging (MALDI‐MSI) of latent fingerprints, the use of development powders as matrices has not been fully investigated. Carbon forensic powder (CFP), a common nonporous development technique, was shown to be an efficient one‐step matrix; however, a high‐resolution mass spectrometer was required in the low mass range due to carbon clusters. Titanium oxide (TiO2) is another commonly used development powder, especially for dark nonporous surfaces. Here, forensic TiO2 powder is utilized as a single‐step development and matrix technique for chemical imaging of latent fingerprints without the requirement of a high‐resolution mass spectrometer. All studied compounds were successfully detected when TiO2 was used as the matrix in positive mode, although, generally, the overall ion signals were lower than the previously studied CFP. TiO2 provided quality mass spectrometry (MS) images of endogenous and exogenous latent fingerprint compounds. The subsequent addition of traditional matrices on top of the TiO2 powder was ineffective for universal detection of latent fingerprint compounds. Forensic TiO2 development powder works as an efficient single‐step development and matrix technique for MALDI‐MSI analysis of latent fingerprints in positive mode and does not require a high‐resolution mass spectrometer for analysis. 相似文献