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   925篇
  免费   20篇
  国内免费   3篇
化学   653篇
晶体学   8篇
力学   33篇
数学   97篇
物理学   157篇
  2023年   4篇
  2022年   23篇
  2021年   28篇
  2020年   28篇
  2019年   28篇
  2018年   26篇
  2017年   23篇
  2016年   33篇
  2015年   28篇
  2014年   31篇
  2013年   49篇
  2012年   52篇
  2011年   77篇
  2010年   60篇
  2009年   42篇
  2008年   84篇
  2007年   48篇
  2006年   41篇
  2005年   42篇
  2004年   27篇
  2003年   33篇
  2002年   28篇
  2001年   17篇
  2000年   24篇
  1999年   9篇
  1998年   6篇
  1997年   8篇
  1996年   3篇
  1995年   5篇
  1994年   9篇
  1993年   3篇
  1992年   4篇
  1991年   4篇
  1990年   2篇
  1988年   2篇
  1987年   1篇
  1985年   3篇
  1984年   1篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1976年   1篇
  1974年   2篇
  1972年   1篇
  1968年   1篇
排序方式: 共有948条查询结果,搜索用时 31 毫秒
231.
232.
Considered one of the chronic diseases in a global state of emergency, diabetes mellitus (DM) may cover an area of 629 million people affected by 2045. The main route of hyperglycemia in the human body is associated with the action of the enzyme aldose reductase on glucose molecules, resulting in the accumulation of sorbitol in blood and tissue cells. Thus, the present study is a high-throughput virtual screening (HTS) of the various molecular datasets available online, as well as an investigation of the pharmacokinetic properties of absorption, distribution, metabolism, excretion, and toxicity (ADMET) and enzyme inhibition aldose reductase from a series of derivatives of rhodanine-3-acetic acid chalcones (D1-8). Four derivatives (D1-4) showed greater oral bioavailability, as they are anions of low relative polarity, showing better viability to interact with the aldose reductase target with a low toxic response to the host.  相似文献   
233.
The incidence of thrombotic complications in SARS-CoV-2 infections has become a global concern; thus, anticoagulants are an integral part of the treatment. Edoxaban (EDX) is an oral anticoagulant suitable for pharmacologic thromboprophylaxis. Herein, two novel analytical methods for EDX determination in tablets are developed and validated using capillary zone electrophoresis (CZE) and high-performance liquid chromatography (HPLC). Operating conditions such as the electrolyte's concentration and pH value, injection time, volume, and the capillary temperature, were optimized. The methods were successfully validated by establishing the linearity, intra- and inter-day precisions (relative standard deviation [%]), accuracy, and robustness. Adequate separation of excipients and degradation products of EDX generated by stress degradation conditions demonstrated the stability-indicating capability of the methods. The analytical procedures were linear in the range of 25–125 µg/ml (r > 0.999), with the limits of detection and quantification of 3.26 and 10.87 µg/ml for CZE and 0.740 and 2.78 µg/ml for HPLC. Although both methodologies are suitable for determining EDX in tablets, CZE provides a greener alternative due to low-cost analysis using less organic solvents and minimizing waste generation.  相似文献   
234.
Nanoparticles of a new small-pore metal silicate formulated as Na2.9(Nb1.55Fe0.45)Si2O10xH2O and exhibiting the structure of previously reported Rb2(Nb2O4)(Si2O6) ⋅ H2O have been synthesized under mild hydrothermal conditions. Replacement of the bulky Rb+ by smaller Na+ ions was accomplished by stabilizing the framework structure via partial occupancy of the Nb5+ sites by Fe3+ ions. Exploratory ion-exchange assays evidence the considerable potential of this new silicate to remove rare-earth elements from aqueous solutions.  相似文献   
235.
Journal of Thermal Analysis and Calorimetry - Native Amazon palm trees have been target of research and product development especially because of their oil and fat. Tucumã-do-Pará...  相似文献   
236.
Let C be a treelike curve, that is, a reduced curve whose irreducible components meet transversally at disconnecting points ofC. AssumeC has planar singularities. In this note we prove an Autoduality Theorem for C. More precisely, in [6] a natural Abel map A: C $\bar J$ to a certain compactification $\bar J$ of the generalized Jacobian of C has been constructed. In this note we prove that the pullback map $A^* :Pic^0 (\bar J) \to Pic^0 (C)$ is an isomorphism.  相似文献   
237.
A set of fourteen Madeira wines comprising wines produced from four Vitis vinifera L. varieties (Bual, Malvasia, Verdelho and Tinta Negra Mole) that were 3, 6, 10 and 17 years old was analysed using HPLC and an electronic tongue (ET) multisensor system. Concentrations of 24 organic acids, phenolic and furanic compounds were determined by HPLC. The ET consisting of 26 potentiometric chemical sensors with plasticized PVC and chalcogenide glass membranes was used. Significance of the effects of age and variety on the ET response and wine composition with respect to the organic acids, phenolics and furanic derivatives were evaluated using ANOVA—Simultaneous Component Analysis (ASCA). Significance of the effects was estimated using a permutation test (1000 permutations). It was found that effects of age, grape variety and their interaction were significant for the HPLC data set and only the effect of age was significant for the ET data. Calibration models of the HPLC and ET data with respect to the wine age and of the ET data with respect to the concentration of the organic acids and phenolics were calculated using PLS1 regression. Models were validated using cross-validation. It was possible to predict wine age from HPLC and ET data with the accuracy in cross-validation of 2.6 and 1.8 years respectively. The ET was capable of detecting the following components (mean relative error in cross-validation is shown in the parentheses): tartaric (8%), citric (5%), formic (12%), protocatehuic (5%), vanillic (18%) and sinapic (14%) acids, catechin (6%), vanillin (12%) and trans-resveratrol (5%). The ET capability of predicting Madeira wine age with good accuracy (1.8 years) as well as quantify of some organic acids and phenolic compounds was demonstrated.  相似文献   
238.
239.
240.
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