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   839篇
  免费   22篇
  国内免费   3篇
化学   653篇
晶体学   17篇
力学   14篇
数学   42篇
物理学   138篇
  2023年   5篇
  2022年   8篇
  2021年   8篇
  2020年   10篇
  2019年   17篇
  2018年   5篇
  2016年   8篇
  2015年   15篇
  2014年   11篇
  2013年   46篇
  2012年   42篇
  2011年   38篇
  2010年   24篇
  2009年   26篇
  2008年   36篇
  2007年   45篇
  2006年   50篇
  2005年   37篇
  2004年   40篇
  2003年   31篇
  2002年   22篇
  2001年   12篇
  2000年   15篇
  1999年   11篇
  1998年   8篇
  1997年   11篇
  1996年   10篇
  1995年   11篇
  1993年   16篇
  1992年   7篇
  1991年   10篇
  1990年   6篇
  1988年   8篇
  1987年   7篇
  1986年   5篇
  1985年   12篇
  1984年   17篇
  1983年   5篇
  1982年   12篇
  1981年   16篇
  1980年   15篇
  1979年   6篇
  1978年   9篇
  1977年   11篇
  1976年   17篇
  1975年   13篇
  1974年   18篇
  1973年   15篇
  1972年   4篇
  1968年   4篇
排序方式: 共有864条查询结果,搜索用时 203 毫秒
41.
An organic salt composed 9,10-bis(4-aminophenyl)anthracene and hypophosphorous acid emits yellow-green fluorescence in the crystalline state. The salt also gives water inclusion crystal which provides blue-green fluorescence. Single X-ray crystal studies revealed that water molecules induced the fluorescence change resulting from reaggregation of molecular packing.  相似文献   
42.
43.
Abstract

Some reactions of diphosphenes and the related species involving oxidation, reduction, alkylation, sulfurization, and 6η-coordination are described.  相似文献   
44.
45.
The diffusion coefficients of Li in the NaTl-type Li intermetallic compound of β-LiGa have been measured by using a short-lived radioactive diffusion tracer. As the tracer, the α-emitting radioisotope of 8Li delivered as the energetic and pulsed beam from Tokai Radioactive Ion Accelerator Complex (TRIAC) was implanted into the β-LiGa compounds with the composition in the range of about 43 to 54 at.% Li. By analyzing the time-dependent yields of the α-particles measured according to the repetition cycle of the beam, the tracer diffusion coefficients were extracted over the wide range of Li composition. Abnormal composition-dependence of Li diffusion coefficients in β-LiGa was observed; the stoichiometric β-LiGa showed the highest diffusivity of Li. By referring to the composition-dependent diffusivity of Li in the iso-structural β-LiAl and β-LiIn, we could identify the abnormal diffusion of Li in very Li-poor composition of β-LiGa. The anomaly has been discussed qualitatively in terms of the formation of defect complex and the interaction between the constitutional defects.  相似文献   
46.
We classify normal supersingular K 3 surfaces Y with total Milnor number 20 in characteristic p,where p is an odd prime that does not divide the discriminant of the Dynkin type of the rational double points on Y.This paper appeared in preprint form in the home page of the first author in the year 2005.  相似文献   
47.
Metal complexes of covalently bound porphyrins are used as sensitive probes for several investigations. Substituted derivatives of tetraphenyl-porphin, phthalocyanine, and naphthalocyanine are synthesized at positively and negatively charged as well as uncharged polymers. The photo-redox activities were studied under irradiation with visible light in the presence of a donor and an acceptor. The triplet life times of covalently bound porphyrin moieties are strongly enhanced compared with the analogous monomeric porphyrins. In addition, the polymer binding results in higher photocatalytic activity. The electron-transfer reactions of Mn(III)-containing porphyrins using the reducing agent dithionite are strongly influenced by the polymer environment. In contrast to monomeric Mn(III)-porphyrins, the porphyrins containing polymers exhibit a two-step reduction which may be due to the change of the conformation of the polymer coil. The catalytic epoxidation of 2,5-dihydrofuran with hypochlorite with formation of 3,4-epoxytetrahydrofuran occurs with water-soluble porphyrins in water. No influence of the polymer environment exists. The different reactions require reaction times from milliseconds up to hours.  相似文献   
48.
49.
Anti‐MUC1 monoclonal antibodies (mAbs) are powerful tools that can be used to recognize cancer‐related MUC1 molecules, the O‐glycosylation status of which is believed to affect binding affinity. We demonstrate the feasibility of using a rapid screening methodology to elucidate those effects. The approach involves i) “one‐bead‐one‐compound”‐based preparation of bilayer resins carrying glycopeptides on the shell and mass‐tag tripeptides coding O‐glycan patterns in the core, ii) on‐resin screening with an anti‐MUC1 mAb, iii) separating positive resins by utilizing secondary antibody conjugation with magnetic beads, and (iv) decoding the mass‐tag that is detached from the positive resins pool by using mass spectrometric analysis. We tested a small library consisting of 27 MUC1 glycopeptides with different O‐glycosylations against anti‐MUC1 mAb clone VU‐3C6. Qualitative mass‐tag analysis showed that increasing the number of glycans leads to an increase in the binding affinity. Six glycopeptides selected from the library were validated by using a microarray‐based assay. Our screening provides valuable information on O‐glycosylations of epitopes leading to high affinity with mAb.  相似文献   
50.
A conjugated copper(II) catecholate based metal–organic framework (namely Cu‐DBC) was prepared using a D2‐symmetric redox‐active ligand in a copper bis(dihydroxy) coordination geometry. The π‐d conjugated framework exhibits typical semiconducting behavior with a high electrical conductivity of ca. 1.0 S m?1 at room temperature. Benefiting from the good electrical conductivity and the excellent redox reversibility of both ligand and copper centers, Cu‐DBC electrode features superior capacitor performances with gravimetric capacitance up to 479 F g?1 at a discharge rate of 0.2 A g?1. Moreover, the symmetric solid‐state supercapacitor of Cu‐DBC exhibits high areal (879 mF cm?2) and volumetric (22 F cm?3) capacitances, as well as good rate capability. These metrics are superior to most reported MOF‐based supercapacitors, demonstrating promising applications in energy‐storage devices.  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