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排序方式: 共有339条查询结果,搜索用时 343 毫秒
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In this paper two complementary approaches are used to describe the mechanical behavior of saturated compressible and incompressible porous solids. The macroscopic investigation is based on the mixture theory, restricted by the volume fraction concept. In the micromechanical approach, a hierarchy of conditionally ensemble averaged fluid and solid phase momentum balance equations are derived for a simple model of quasi-static liquid saturated porous media. The ensemble averaged equations for both the phases agree remarkably well with the macroscopic results. A micromechanical basis for Terzhagi's effective stress concept is presented. In addition, an expression for additional partial solid stress modifying the effective stress principle, to account for deformability of solid materials, is also derived. 相似文献
94.
Ties Behnke 《Pramana》2007,69(5):697-702
In preparation of the experimental program at the international linear collider (ILC), the large detector concept (LDC) is
being developed. The main points of the LDC are a large volume gaseous tracking system, combined with high precision vertex
detector and an extremely granular calorimeter. The main design force behind the LDC is the particle flow concept.
for the LDC Concept Group 相似文献
95.
Max Jammer 《Physics in Perspective (PIP)》2007,9(3):266-280
I summarize the historical development of concepts of time in physics from antiquity to the end of the twentieth century.
Editors’ Note: Max Jammer received the American Physical Society/American Institute of Physics Abraham Pais Prize for the
History of Physics for 2007, “For his groundbreaking historical studies of fundamental concepts in physics, including his
comprehensive account of the development of quantum mechanics.” We publish here his Pais Prize Lecture, which was presented
at the APS meeting in Jacksonville, Florida, on April 16, 2007. 相似文献
96.
A vertex detector concept of the linear collider flavour identification (LCFI) collaboration, which studies pixel detectors
for heavy quark flavour identification, has been implemented in simulations for c-quark tagging in scalar top studies. The production and decay of scalar top quarks (stops) is particularly interesting for
the development of the vertex detector as only two c-quarks and missing energy (from undetected neutralinos) are produced for light stops. Previous studies investigated the vertex
detector design in scenarios with large mass differences between stop and neutralino, corresponding to large visible energy
in the detector. In this study we investigate the tagging performance dependence on the vertex detector design in a scenario
with small visible energy for the international linear collider (ILC).
相似文献
97.
K. Mühle P. Harting I. Maass D. Missbach H. M. Nitzsche G. Weise 《Isotopes in environmental and health studies》2013,49(4):273-304
It is the proper aim of geochemical investigations regarding natural gas to describe the processes of generation, migration and accumulation of gaseous compounds. By this way our research results should contribute to knowledge about the gas generating potential of organic matter and about the expected gas volumes in natural gas deposits. The main topics in the authors' research project are - isotopic characterization of hydrocarbon forming organic matter - simulation of the generation of natural gas components by coalification processes (model experiments including also radiolytic gas formation from organic matter) - investigation of various separation processes (diffusion, adsorption, solubility, mixing of gases. oxidation of natural gas components) affecting chemical compositions and isotopic signatures - elucidation of pressure and temperature dependence of separation processes and especially of the elementary isotope separation cofficients in systems gas/sorbent - as the main result, an interpretation concept for natural gas samples is proposed which is based on chemical and isotopic compositions of methane and ethane in the samples and which takes into consideration also separation processes. Following this summarizing publication some of the most important results of our research work will be presented in more detail in three separate parts. 相似文献
98.
G.M. Katyba K.I. Zaytsev I.N. Dolganova I.A. Shikunova N.V. Chernomyrdin S.O. Yurchenko G.A. Komandin I.V. Reshetov V.V. Nesvizhevsky V.N. Kurlov 《Progress in Crystal Growth and Characterization of Materials》2018,64(4):133-151
Second half of the XX century was marked by a rapid development of sapphire shaped crystal growth technologies, driven by the demands for fast, low-cost, and technologically reliable methods of producing sapphire crystals of complex shape. Numerous techniques of shaped crystal growth from a melt have been proposed relying on the Stepanov concept of crystal shaping. In this review, we briefly describe the development of growth techniques, with a strong emphasize on those that yield sapphire crystals featuring high volumetric and surface quality. A favorable combination of physical properties of sapphire (superior hardness and tensile strength, impressive thermal conductivity and chemical inertness, high melting point and thermal shock resistance, transparency to electromagnetic waves in a wide spectral range) with advantages of shaped crystal growth techniques (primarily, an ability to produce sapphire crystals with a complex geometry of cross-section, along with high volumetric and surface quality) allows fabricating various instruments for waveguiding, sensing, and exposure technologies. We discuss recent developments of high-tech instruments, which are based on sapphire shaped crystals and vigorously employed in biomedical and material sciences, optics and photonics, nuclear physics and plasma sciences. 相似文献
99.
100.
Systemic view of learning scientific concepts: A description in terms of directed graph model
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Ismo T. Koponen 《Complexity》2014,19(3):27-37
This study suggests a systemic view on concept learning, in which concepts are seen as complex, dynamically evolving structures with robust and persistent patterns emerging from loosely connected elemental pieces. The model is represented in the form of a directed graph, and it explains many empirically identified features of learning paths, including: (1) the stability of learned concepts, (2) changes in concept attributions (ontological shift) as guided by theoretical knowledge, and (3) the evolution of concepts as driven by model competition with the accumulation of evidence. The results thus show applicability of the systemic view and the directed graph model. © 2013 Wiley Periodicals, Inc. Complexity 19: 27–37, 2014 相似文献