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   1260篇
  免费   72篇
  国内免费   1篇
化学   920篇
晶体学   2篇
力学   24篇
数学   199篇
物理学   188篇
  2024年   3篇
  2023年   32篇
  2022年   27篇
  2021年   30篇
  2020年   55篇
  2019年   64篇
  2018年   29篇
  2017年   29篇
  2016年   66篇
  2015年   58篇
  2014年   47篇
  2013年   54篇
  2012年   97篇
  2011年   88篇
  2010年   51篇
  2009年   32篇
  2008年   58篇
  2007年   75篇
  2006年   65篇
  2005年   71篇
  2004年   52篇
  2003年   25篇
  2002年   24篇
  2001年   8篇
  2000年   7篇
  1999年   14篇
  1998年   9篇
  1997年   11篇
  1996年   9篇
  1994年   5篇
  1993年   5篇
  1992年   4篇
  1990年   5篇
  1989年   3篇
  1988年   6篇
  1987年   6篇
  1986年   10篇
  1985年   5篇
  1983年   6篇
  1981年   3篇
  1980年   6篇
  1979年   9篇
  1976年   10篇
  1975年   5篇
  1973年   10篇
  1969年   3篇
  1968年   3篇
  1934年   3篇
  1932年   3篇
  1922年   2篇
排序方式: 共有1333条查询结果,搜索用时 500 毫秒
961.
Conclusions Neutrophils can be directly stimulated by endothelial cell suspensions, an observation that has also been made by experiments with nylon fiber, as an artificial model for PMNL/EC interactions [5]. As shown by experiments with endothelial cell suspensions a further amplification of this process following LPS-priming up to 10 ng/ml blood has been demonstrated.Unstimulated neutrophils do not lead to an endothelial cell damage, as also could be demonstrated by electron micrographs. An increased 111In release occurred following neutrophil stimulation between 10 and 20 ng LPS/ml blood, but cannot be explained by an increased oxygen radical production of neutrophils. Therefore, these data suggest, that other neutrophil derived products rather than oxygen radicals contribute to an endothelial cell damage in this system.
Chemiluminescenz-Antwort und Endothelzellschaden nach Lipopolysaccharid-Stimulation polymorphkerniger Leukocyten
  相似文献   
962.
This is a report on the single and double charge exchange reactions on nuclie. The emphasis is on recent experimental results and calculations. We limit ourselves to pion energies below 300 MeV. The experimental results and complexity. We present the current level of understanding of the various aspects of the charge exchange process.  相似文献   
963.
964.
965.
The photoelectrochemical behavior of a polymer electrode based on poly(3,4-ethylenedioxythiophene) (PEDT) is studied in acetonitrile solutions during the cathodic reduction of oxygen. The measurements are taken on PEDT films 490 nm thick deposited onto a platinum support in oxygen-saturated 0.1 M Bu4NBF4 solutions. The electrode was illuminated with a light of a wavelength 487 nm from a helium–cadmium laser in conditions of modulated illumination, and in doing so, the real and imaginary components of an alternating photocurrent were measured at different modulation frequencies. The peculiarity of the photoelectrochemical behavior of PEDT manifests itself in the emergence of an anodic photocurrent, which increases with a change in potential in the cathodic direction. At low modulation frequencies, the real and imaginary components are of the same sign, whereas at high modulation frequencies the components have opposite signs (photocurrent lags behind a change in the light intensity). The emergence of an anodic photocurrent is connected with the cathodic reduction of oxygen and the formation in a near-electrode layer of radical anion O 2. Such a behavior of PEDT, which makes it different from other polymers of the thiophene series, is explained by different potentials of their anodic oxidation, to which a conductive state of the polymer is related.  相似文献   
966.
Zusammenfassung LetD:G→GL(n,C) be an irreducible linear representation of a finite groupG with the characterX. IfD is realizible in Q(ξ m ) and Q(ξ m′ ) we give a condition for then realizability ofD in Q(ξ(m′)). If the degreen is a prime ≠ 2, we show thatD realizible in Q(ξ f ), wheref is the conductor of the abelian extensionQ(X)/Q.  相似文献   
967.
In this paper a review of application of Bayesian approach to global and stochastic optimization of continuous multimodal functions is given. Advantages and disadvantages of Bayesian approach (average case analysis), comparing it with more usual minimax approach (worst case analysis) are discussed. New interactive version of software for global optimization is discussed. Practical multidimensional problems of global optimization are considered  相似文献   
968.
Abstract— Bleached purple membrane normally binds Ca2+ and Mg2+, which can be removed by the divalent cation chelator ethylenediaminetetraacetic acid (EDTA). Regeneration of pigments from EDTA-treated bleached membrane (apomembrane) and retinal leads to the formation of blue membrane at pH 4.8, and purple membrane at neutral pH. The pigments take much longer to regenerate than with un-deionized apoprotein. Adding back cations to the deionized apomembrane only partially speeds up the regeneration process. Like native purple membrane, the regenerated purple membrane also undergoes a photocycle and shows a light-induced proton release and uptake, although with much slower kinetics than the native species. Thus, cations control the kinetics of pigment regeneration, and also some aspects of the pigment's conformation which controls the photocycle kinetics. The removal and replacement of the cations is not completely reversible, suggesting the cations are not merely bound in the double layer.  相似文献   
969.
970.
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