全文获取类型
收费全文 | 1002篇 |
免费 | 116篇 |
国内免费 | 109篇 |
专业分类
化学 | 673篇 |
晶体学 | 3篇 |
力学 | 69篇 |
综合类 | 32篇 |
数学 | 73篇 |
物理学 | 377篇 |
出版年
2024年 | 2篇 |
2023年 | 21篇 |
2022年 | 47篇 |
2021年 | 60篇 |
2020年 | 38篇 |
2019年 | 44篇 |
2018年 | 21篇 |
2017年 | 36篇 |
2016年 | 46篇 |
2015年 | 28篇 |
2014年 | 71篇 |
2013年 | 138篇 |
2012年 | 51篇 |
2011年 | 39篇 |
2010年 | 35篇 |
2009年 | 49篇 |
2008年 | 41篇 |
2007年 | 46篇 |
2006年 | 56篇 |
2005年 | 37篇 |
2004年 | 38篇 |
2003年 | 37篇 |
2002年 | 108篇 |
2001年 | 26篇 |
2000年 | 18篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有1227条查询结果,搜索用时 15 毫秒
101.
This research work is intended to compare the anti-corrosive properties of three generations of inorganic phosphate pigments in solvent-based paints and in water-borne ones, both of the epoxy type. The anti-corrosive properties of phosphate pigments were assessed by means of electrochemical techniques (corrosion potential measurements, polarisation tests, etc.), employing a steel electrode dipped into pigments suspensions. The behaviour of these pigments in anti-corrosive paints, formulated with different binders, have been studied by accelerated (salt spray cabinet and humidity chamber) and electrochemical tests (corrosion potential and ionic resistance measurements).Accelerated and electrochemical tests allowed to differentiate the anti-corrosive performance of the three phosphates studied in this research. These test are also able to detect and characterise possible synergism between the water-borne resin and the pigments. 相似文献
102.
We analytically investigate the dynamics of quantum Fisher information of two qubits in independent environments for both uncorrelated and entangled input states. Especially, we observe that, in the non-Markovian regime and resonant case, quantum Fisher information of uncorrelated input state vanishes only at discrete time point whereas that of entangled input state can disappear during finite time interval. It shows that quantum Fisher information, which determines the parameter estimation precision, is strongly affected by the environment memory effects, and the advantage of entanglement-enhance metrology no longer exists even for a very short time. We also note that quantum Fisher information for two kinds of input states can be preserved under appropriate qubit-reservoir detuning. 相似文献
103.
:本文介绍了国际上关于环境电磁学及电磁兼容技术的一些科研进展情况,描述了电磁兼容的动态,最后并提出了若干建议. 相似文献
104.
Renal Clearable Luminescent WSe2 for Radioprotection of Nontargeted Tissues during Radiotherapy 下载免费PDF全文
Haixia Liu Junying Wang Yaqi Jing Jiang Yang Xueting Bai Xiaoyu Mu Fujuan Xu Xuhui Xue Lingfang Liu Yuan‐Ming Sun Qiang Liu Haitao Dai Changlong Liu Xiao‐Dong Zhang 《Particle & Particle Systems Characterization》2017,34(6)
High‐energy ionizing radiation is widely used in medical diagnosis and cancer radiation therapy. However, high‐energy radiation can also impose significant damages in healthy tissues during medical treatments via direct DNA damages and indirect damages from production of reactive oxygen species (ROS). Therefore, it is urgent to develop highly effective radioprotectants with low toxicities that can meet the increasing needs for alleviating the adverse effects from cancer radiation therapy and nuclear emergency. In this work, strongly catalytic ultrasmall (sub‐5 nm) cysteine‐protected WSe2 dots are employed to protect healthy tissues against radiation via diminishing radiation‐induced free radicals. The WSe2 dots with high surface activities can recover radiation‐induced DNA damages and eliminate the excessive ROS generated from radiation. In vivo experiments confirm that the survival rate of mice treated with WSe2 dots is significantly elevated with radiation damages postponed under exposure to high‐dose ionizing radiation. Furthermore, the free radicals in major organs and hematological system can be appreciably omitted, suggesting their unique role as free radical scavengers. These WSe2 dots in ultrasmall size show rapid renal clearance of ≈74% injection dose via urine excretion in 24 h and do not cause any apparent toxicity in vivo for up to 30 d. 相似文献
105.
基于SRLG约束和资源共享的交迭段保护机制研究 总被引:1,自引:0,他引:1
通过对共享风险链路组约束机制和交迭段保护机制的分析,将两者相结合并根据工作和保护路径分别采用动态链路权重调整,提出了一种基于共享风险链路组不相关的交迭段共享保护算法.交迭段共享保护算法在共享风险链路组不相关的约束条件下,为整个工作路由提供了多个交迭的保护段,并给出了一种能够合理有效选择这些交迭保护段的方法.对交迭段共享保护算法的分析和仿真结果表明,与以往保护算法相比,交迭段共享保护算法不但大大提高了网络连接的可靠性,而且还通过不同交迭保护段间资源的合理共享,有效地提高了网络资源的利用率. 相似文献
106.
针对城市消防联网远程监控系统中实时信息数据逐渐增长而引出的大数据问题,传统的消防系统无法实时、高效地处理消防实时数据的问题,提出了一种基于云计算和Storm实时数据处理系统的解决方案;对于开源的Storm框架进行需求和性能分析,实现对其技术架构上的改进,并结合消防系统的特点,提出一套高实时性、高可扩展性的消防联网监控中心的数据实时处理的体系架构,同时也进行了云计算平台的搭建,利用心跳检测机制保证各个监控单位的实时性连接;研究表明,基于云计算和Storm平台架构完全适用于消防联网监控中心的实时消防数据的处理,具有高效性、高可靠性、性能显著等特性。 相似文献
107.
AMT在青铜器文物表面形成缓蚀膜的计算分析 总被引:1,自引:0,他引:1
利用密度泛函(DFT)、概念DFT、Electron Localization Function(ELF)和Fukui函数中的亲电反应函数及Multiwfn软件,在B3LYP/6-311+G(d,p)基组水平上研究了5-氨基-2-巯基-1,3,4-噻二唑[AMT(a)]及其同分异构体[AMT(b)]和四面体型配合物i Thiol-Cu-2AMT的几何构型和反应特性.通过计算研究发现,首先AMT(b)与青铜器表面的Cu2+形成平面型配合物i Thiol-Cu后再与AMT(b)相互作用,并最终形成不规则的四面体型i Thiol-Cu-2AMT.在i Thiol-Cu-2AMT中Cu19能与AMT(b)中的亲核性原子有效地结合,形成四面体结构后将Cu19离子保护起来,达到了保护青铜器不受腐蚀的目的;对i Thiol-Cu-2AMT结构中的活性位置分析及ELF拓扑研究后发现,在i Thiol-Cu-2AMT中N6、N15、S26和S35原子又可以与其它的Cu2+相互作用,逐步形成配位型聚合物保护膜[i Thiol-Cu-2AMT]n. 相似文献
108.
《中国物理 B》2014,(9):622-622
Chinese Physics B(Chin.Plivs.B).formerly titled Chinese Physics,is an international compreliensive academic journal,aiming to publish original papers and rapid communications reflecting creative and innovative achievements in physics,as well review papers about important accomplishments in frontier of physics.The journal is published monthly in English by the Chinese Physical Society(CPS)and the IOP Publishing.Chin. 相似文献
110.
《中国光学快报(英文版)》2014,(10):F0003-F0003
Chinese Optics Letters is a short-article journal for the rapid dissemination of new, important results in all branches of optical science and technology and related fields, published monthly by Chinese Laser Press and distributed abroad by the Optical Society (OSA). 相似文献