全文获取类型
收费全文 | 8302篇 |
免费 | 412篇 |
国内免费 | 192篇 |
专业分类
化学 | 5120篇 |
晶体学 | 79篇 |
力学 | 342篇 |
综合类 | 25篇 |
数学 | 1263篇 |
物理学 | 2077篇 |
出版年
2023年 | 76篇 |
2022年 | 177篇 |
2021年 | 187篇 |
2020年 | 195篇 |
2019年 | 199篇 |
2018年 | 185篇 |
2017年 | 161篇 |
2016年 | 249篇 |
2015年 | 250篇 |
2014年 | 275篇 |
2013年 | 548篇 |
2012年 | 490篇 |
2011年 | 532篇 |
2010年 | 340篇 |
2009年 | 308篇 |
2008年 | 409篇 |
2007年 | 352篇 |
2006年 | 348篇 |
2005年 | 301篇 |
2004年 | 238篇 |
2003年 | 244篇 |
2002年 | 229篇 |
2001年 | 173篇 |
2000年 | 157篇 |
1999年 | 124篇 |
1998年 | 82篇 |
1997年 | 77篇 |
1996年 | 85篇 |
1995年 | 65篇 |
1994年 | 102篇 |
1993年 | 79篇 |
1992年 | 97篇 |
1991年 | 74篇 |
1990年 | 77篇 |
1989年 | 52篇 |
1988年 | 67篇 |
1987年 | 54篇 |
1986年 | 55篇 |
1985年 | 90篇 |
1984年 | 86篇 |
1983年 | 68篇 |
1982年 | 83篇 |
1981年 | 67篇 |
1980年 | 84篇 |
1979年 | 72篇 |
1978年 | 82篇 |
1977年 | 72篇 |
1976年 | 76篇 |
1975年 | 49篇 |
1973年 | 49篇 |
排序方式: 共有8906条查询结果,搜索用时 15 毫秒
941.
We study some minimization problems for Hamiltonian stationaryLagrangian surfaces in R4. We show that the flat Lagrangian torusS
1 × S
1 minimizes the Willmore functional among Hamiltonianstationary tori of its isotopy class, which gives a new proof of thefact that it is area minimizing in the same class. Considering theLagrangian flat cylinder as a torus in some quotient space R4/v Z, we show that it is also area minimizing in its isotopy class. 相似文献
942.
943.
Dominique Delbourg Gérard Penillault Tran Khan Tuong Martial Decourt Nicole Borome Henri Harroch Bertrand Lessellier Bernard Waast Jean Pierre Mouffron 《Pramana》2002,59(6):1025-1033
A new control system was designed for the tandem MP-9 at Orsay. Because of the existing devices located on high voltage platforms
and the lack of space inside the accelerator, in-house electronic cards based on micro-controllers and an optical fieldbus
were developed to collect data. VME processors under VxWorks, a real time operating system, manage the fieldbus, concentrate
the accelerator information and transmit it to the supervisory software through the ethernet network. This software consists
of a collection of Java virtual machines (JVM) running on several Unix work-stations and PCs under Windows. Some of the Java
virtual machines manage apparatus, instruments, local display and connections to an object database and VME concentrators.
Other manage general synoptics. JVMs communicate between themselves with RMI protocol and JRPC with VME concentrators. So
the supervisory software can be spread over several control stations throughout the network. 相似文献
944.
945.
946.
In the design of a system, the comparison of possible solutions using simulation is generally performed with fixed environmental conditions. In practice, however, unexpected changes can occur for example in the part mix of a manufacturing facility or in the customer demand. Such changes, which are considered as modifications in environmental factors, can impact the system response. As a consequence, a solution A that is better than B for a given environment, can yield poorer performance than B for another environment. Therefore, we are interested in robust simulation studies, which aim at taking into account several possible environments. In methods based on Taguchi’s principles, no distinction is made between these environments in the robustness computation. In the suggested heuristic approach, we focus on problems where a particular environment is expected when the system will be in operation (the others being unexpected environments). This particular environment will be considered in the study as a “base environmental scenario”. The robustness of a solution of the design problem is computed as an approximate measure of what will be saved or lost if the environment becomes the unexpected. Reference curves are suggested to allow these solutions to be empirically compared in accordance with the decision-maker’s requirements. A simplified example is provided. The results are different from those obtained using a signal to noise ratio, which is typically used in Taguchian approaches. 相似文献
947.
R. T. de Souza N. Le Neindre A. Pagano K. -H. Schmidt 《The European Physical Journal A - Hadrons and Nuclei》2006,30(1):275-291
This review on second- and third-generation multidetectors devoted to heavy-ion collisions aims to cover the last twenty years.
The presented list of devices is not exhaustive but regroups most of the techniques used during this period for nuclear reactions
at intermediate energy (≃ 10A MeV to 1A GeV), both for charged-particle and neutron detection. The main part will be devoted
to 4π multidetectors, projectile decay fragmentation, high-resolution magnetic spectrometers, auxiliary detectors and neutron
detection. The last part will present the progress in electronics and detection in view of the construction of future-generation
detectors. 相似文献
948.
The gas phase reaction of OH radicals with hydrogen iodide (HI) has been studied using a Laser Photolysis-Resonance Fluorescence (LP-RF) apparatus, recently developed in our group. The measured rate constant at 298 K was (2.7 ± 0.2) × 10−11 cm3 molecule−1 s−1. This rate constant is compared with the ones of the reactions OH + HCl and OH + HBr. The role of the reaction OH + HI in marine tropospheric chemistry is discussed. In addition, the LP-RF apparatus was tested and validated by measuring the following rate constants (in cm3 molecule−1 s−1 units): 𝓀(OH + HNO3) = (1.31 ± 0.06) × 10−13 at p = 27 and 50 Torr of argon and 𝓀(OH + C3H8) = (1.22 ± 0.08) × 10−12. These rate constants are in very good agreement with the literature data. 相似文献
949.
Alain Pruvost François Becher Patrick Bardouille Catherine Guerrero Christophe Creminon Jean-François Delfraissy Cécile Goujard Jacques Grassi Henri Benech 《Rapid communications in mass spectrometry : RCM》2007,21(13):2167-2167
The original article to which this Erratum refers was published in Rapid Commun Mass Spectrom. 2001; 15 : 1401–1408. 相似文献
950.