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   827篇
  免费   24篇
  国内免费   12篇
化学   484篇
晶体学   1篇
力学   23篇
数学   174篇
物理学   181篇
  2022年   6篇
  2020年   9篇
  2019年   9篇
  2016年   21篇
  2015年   13篇
  2014年   16篇
  2013年   30篇
  2012年   30篇
  2011年   47篇
  2010年   10篇
  2009年   12篇
  2008年   31篇
  2007年   24篇
  2006年   41篇
  2005年   36篇
  2004年   33篇
  2003年   31篇
  2002年   36篇
  2001年   22篇
  2000年   25篇
  1999年   10篇
  1998年   10篇
  1997年   11篇
  1996年   11篇
  1995年   11篇
  1994年   7篇
  1993年   12篇
  1992年   8篇
  1991年   10篇
  1990年   11篇
  1989年   9篇
  1988年   14篇
  1987年   11篇
  1986年   9篇
  1985年   13篇
  1984年   11篇
  1983年   9篇
  1982年   10篇
  1981年   10篇
  1980年   8篇
  1979年   9篇
  1978年   10篇
  1977年   10篇
  1976年   14篇
  1975年   14篇
  1974年   7篇
  1973年   8篇
  1972年   7篇
  1971年   6篇
  1968年   6篇
排序方式: 共有863条查询结果,搜索用时 12 毫秒
31.
The diffractive production of charmed strangeD s * and possiblyD s mesons by neutrinos and antineutrinos on nucleons in hydrogen, deuterium and neon targets is observed. The slope parameter of thet distribution is 3.3±0.8 (GeV)?2. The production rate per charged current neutrino interaction with an isoscalar target times the D s + →φτ+ branching fraction is (1.03±0.27)×10?4.  相似文献   
32.
We demonstrate the acquisition of stimulated Raman scattering spectra with the use of a single femtosecond pulse. High-resolution vibrational spectra are obtained by shifting the phase of a narrow band of frequencies within the input pulse spectrum, using spectral shaping. The vibrational lines are resolved via amplitude features formed in the spectrum after interaction with the sample. Using this technique, low-frequency Raman lines (<100 cm?1) are observed on both the Stokes and anti-Stokes sides.  相似文献   
33.
Asratyan  A. E.  Aderholz  M.  Ammosov  V. V.  Gapienko  G. S.  Gapienko  V. A.  Guy  J.  Jones  G. T.  Kaftanov  V. S.  Katz  U. F.  Kern  J.  Korotkov  V. A.  Krutchinin  S. P.  Kubantsev  M. A.  Marage  P.  Morrison  D. R. O.  Sacton  J.  Schmitz  N.  Varvell  K.  Venus  W.  Wittek  W.  Zaetz  V. G. 《Zeitschrift fur Physik C Particles and Fields》1994,61(4):563-565
Zeitschrift für Physik C Particles and Fields - Neutrino interactions in BEBC produce theD ** (2536) charmed strange meson. The mass of this state is 2534.2±1.2 MeV. The production rate...  相似文献   
34.
Jones  G. T.  Jones  R. W. L.  Kennedy  B. W.  Klein  H.  Morrison  D. R. O.  Wachsmuth  H.  Miller  D. B.  Mobayyen  M. M.  Wainstein  S.  Aderholz  M.  Hantke  D.  Katz  U. F.  Kern  J.  Schmitz  N.  Wittek  W.  Borner  H. P.  Myatt  G.  Cooper-Sarkar  A. M.  Guy  J.  Venus  W.  Bullock  F. W.  Burke  S. 《Zeitschrift fur Physik C Particles and Fields》1994,63(4):601-609
Zeitschrift für Physik C Particles and Fields - A set of proton longitudinal polarized distributions, worked out under the assumption of small gluon polarization, is used to evaluate several...  相似文献   
35.
R B Katz  J Mistry  M B Mitchell 《合成通讯》2013,43(1-2):317-325
The reaction of N-methoxy-derivatives of pyridines in methanol with ammonium persulphate gives improved yields of mono-hydroxymethylated products. In contrast to the original Minisci procedure the reaction requires only catalytic amounts of ammonium persulphate. Evidence is presented which establishes that the reaction does not proceed via an intramolecular pathway.  相似文献   
36.
DNA release electrochemically stimulated by applying ?10 mV on the modified electrode was studied. The release process was based on the local (interfacial) pH change produced upon H2O2 reduction electrocatalyzed by the immobilized microperoxidase‐11. SiO2 nanoparticles attached to the electrode surface and functionalized with trigonelline and boronic acid species changed their electrical charge from positive to negative upon the interfacial pH change, thus allowing electrostatic adsorption of negatively charged DNA on the positive interface and then its repulsion/release from the negative interface. The loaded/released DNA molecules were labeled with a fluorescent dye to allow easy detection of the released DNA molecules. The important feature of the developed system is the controlled DNA release upon applying very small electrical potential on the modified electrode.  相似文献   
37.
Zeitschrift für Physik A Hadrons and nuclei - Im Röntgenspektrogramm der meisten Flüssigkeiten tritt nur ein einziger intensiver „amorpher Ring“ auf. Dessen Zusammenhang...  相似文献   
38.
Summary The chain complex of a twisted free product A*t, FK, is chain homotopy equivalent to a differential graded algebra, which is identified to be a confibration of algebras as defined by Quillen. Under certain connectivity conditions we obtain a long exact sequence connecting the homologies of A, K, and A*t FK. In particular we derive a long exact sequence connecting the homologies of Y, X and (Y Ug CX) (, C, are the loop, the cone and the suspension constructions respectively). A chain complex equivalent to the chain complex of the Milnor free group FX is recognized, from which results a theorem of Bott and Samelson that H(X) is freely generated as a graded algebra by H(X).  相似文献   
39.
A half‐adder and a half‐subtractor have been realized using enzymatic reaction cascades performed in a flow cell device. The individual cells were modified with different enzymes and assembled in complex networks to perform logic operations and arithmetic functions. The modular design of the logic devices allowed for easy re‐configuration, enabling them to perform various functions. The final output signals, represented by redox species [Fe(CN)6]3?/4? or NADH/NAD+, were analyzed optically to derive the calculation results. These output signals might be applicable in the future for actuation processes, for example, substance release activated by logically processed signals.  相似文献   
40.
A “smart” biofuel cell switchable ON and OFF upon application of several chemical signals processed by an enzyme logic network was designed. The biocomputing system performing logic operations on the input signals was composed of four enzymes: alcohol dehydrogenase (ADH), amyloglucosidase (AGS), invertase (INV) and glucose dehydrogenase (GDH). These enzymes were activated by different combinations of chemical input signals: NADH, acetaldehyde, maltose and sucrose. The sequence of biochemical reactions catalyzed by the enzymes models a logic network composed of concatenated AND/OR gates. Upon application of specific “successful” patterns of the chemical input signals, the cascade of biochemical reactions resulted in the formation of gluconic acid, thus producing acidic pH in the solution. This resulted in the activation of a pH-sensitive redox-polymer-modified cathode in the biofuel cell, thus, switching ON the entire cell and dramatically increasing its power output. Application of another chemical signal (urea in the presence of urease) resulted in the return to the initial neutral pH value, when the O2-reducing cathode and the entire cell are in the mute state. The reversible activation–inactivation of the biofuel cell was controlled by the enzymatic reactions logically processing a number of chemical input signals applied in different combinations. The studied biofuel cell exemplifies a new kind of bioelectronic device where the bioelectronic function is controlled by a biocomputing system. Such devices will provide a new dimension in bioelectronics and biocomputing benefiting from the integration of both concepts.  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