首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2969篇
  免费   261篇
  国内免费   14篇
化学   2213篇
晶体学   15篇
力学   63篇
数学   423篇
物理学   530篇
  2023年   53篇
  2022年   35篇
  2021年   122篇
  2020年   167篇
  2019年   187篇
  2018年   83篇
  2017年   69篇
  2016年   199篇
  2015年   149篇
  2014年   160篇
  2013年   213篇
  2012年   278篇
  2011年   271篇
  2010年   155篇
  2009年   129篇
  2008年   197篇
  2007年   161篇
  2006年   154篇
  2005年   108篇
  2004年   67篇
  2003年   32篇
  2002年   34篇
  2001年   28篇
  2000年   19篇
  1999年   14篇
  1998年   11篇
  1997年   6篇
  1996年   8篇
  1995年   10篇
  1994年   8篇
  1993年   5篇
  1992年   13篇
  1991年   8篇
  1990年   6篇
  1988年   3篇
  1987年   4篇
  1986年   6篇
  1985年   6篇
  1983年   5篇
  1982年   5篇
  1981年   7篇
  1980年   4篇
  1979年   3篇
  1978年   7篇
  1975年   5篇
  1973年   3篇
  1972年   3篇
  1971年   3篇
  1936年   5篇
  1932年   2篇
排序方式: 共有3244条查询结果,搜索用时 371 毫秒
51.
52.
53.
In simulations of liquid metals, various model approximations, each of which justified by experimental results lead to a simplified two-phase flow problem. This paper discusses numerical justifications for these approaches and provides quantitative results for a single rising bubble as a benchmark. Representing a bubble as a rigid object is shown to be valid for low Eötvös numbers in contaminated systems. Qualitative differences can be observed for larger Eötvös numbers. Further simulations are undertaken with different ratios of inner and outer viscosity. The benchmark problem considered may also be interesting for more general applications.  相似文献   
54.
Zeolitic imidazolate framework (ZIF) hybrid fluorescent nanoparticles and ZIF antibody conjugates have been synthesized, characterized, and employed in lateral-flow immunoassay (LFIA). The bright fluorescence of the conjugates and the possibility to tailor their mobility gives a huge potential for diagnostic assays. An enzyme-linked immunosorbent assay (ELISA) with horseradish peroxidase (HRP) as label, proved the integrity, stability, and dispersibility of the antibody conjugates, LC-MS/MS provided evidence that a covalent link was established between these metal-organic frameworks and lysine residues in IgG antibodies.  相似文献   
55.
56.
The sol–gel process is widely used for the production of powders, coatings and bulk materials. However, being a wet-chemical technique, it has certain limitations related to properties of aqueous colloidal solution, especially when applied as a coating. The most frequently used methods, such as dip- and spin-coating, are difficult to apply onto more complex substrates. In these cases, the aerosol–gel deposition method can be regarded as the solution of this problem. In the present article, a novel plasma enhanced aerosol–gel method of coatings production is presented. A novelty of this method is based on an integration of the aerosol–gel deposition of thin films and their low temperature plasma treatment. Owing to the above, all stages of the coatings production process—substrate preparation, film deposition, and its plasma treatment, can be carried out in a single reactor. The design and operational scheme of such device is presented in this work. Using this device, thin coatings were first deposited on substrates and then plasma treated. The effect of deposition and plasma discharge conditions on morphology and chemical structure of the films has been studied. It was found that plasma treatment had a substantial influence on all the examined properties of the aerosol–gel deposited coatings.  相似文献   
57.
Predictions obtained with a confining, symmetry-preserving treatment of a vector ? vector contact interaction at leading-order in a widely used truncation of QCD’s Dyson–Schwinger equations are presented for Δ and Ω baryon elastic form factors and the γN → Δ transition form factors. This simple framework produces results that are practically indistinguishable from the best otherwise available, an outcome which highlights that the key to describing many features of baryons and unifying them with the properties of mesons is a veracious expression of dynamical chiral symmetry breaking in the hadron bound-state problem. The following specific results are of particular interest. The Δ elastic form factors are very sensitive to m Δ. Hence, given that the parameters which define extant simulations of lattice-regularised QCD produce Δ-resonance masses that are very large, the form factors obtained therewith are a poor guide to properties of the Δ(1232). Considering the Δ-baryon’s quadrupole moment, whilst all computations produce a negative value, the conflict between theoretical predictions entails that it is currently impossible to reach a sound conclusion on the nature of the Δ-baryon’s deformation in the infinite momentum frame. Results for analogous properties of the Ω baryon are less contentious. In connection with the N → Δ transition, the Ash-convention magnetic transition form factor falls faster than the neutron’s magnetic form factor and nonzero values for the associated quadrupole ratios reveal the impact of quark orbital angular momentum within the nucleon and Δ; and, furthermore, these quadrupole ratios do slowly approach their anticipated asymptotic limits.  相似文献   
58.
In the present paper we address the problem of optical isomerism embodied in the socalled “Hund’s paradox”, which points to the difficulty to account for chirality by means of quantum mechanics. In particular, we explain the answer to the problem proposed by the theory of decoherence. The purpose of this article is to challenge this answer on the basis of a conceptual analysis of the phenomenon of decoherence, that reveals the limitations of the theory of decoherence to solve the difficulties posed by optical isomerism and, in general, by quantum measurement.  相似文献   
59.
60.
Cancer stem cells (CSC) constitute a cell subpopulation in solid tumors that is responsible for resistance to conventional chemotherapy, metastasis and cancer relapse. The natural product Salinomycin can selectively target this cell niche by directly interacting with lysosomal iron, taking advantage of upregulated iron homeostasis in CSC. Here, inhibitors of the divalent metal transporter 1 (DMT1) have been identified that selectively target CSC by blocking lysosomal iron translocation. This leads to lysosomal iron accumulation, production of reactive oxygen species and cell death with features of ferroptosis. DMT1 inhibitors selectively target CSC in primary cancer cells and circulating tumor cells, demonstrating the physiological relevance of this strategy. Taken together, this opens up opportunities to tackle unmet needs in anti-cancer therapy.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号