全文获取类型
收费全文 | 1348805篇 |
免费 | 25691篇 |
国内免费 | 7788篇 |
专业分类
化学 | 671757篇 |
晶体学 | 20553篇 |
力学 | 74995篇 |
综合类 | 108篇 |
数学 | 241560篇 |
物理学 | 373311篇 |
出版年
2021年 | 13509篇 |
2020年 | 15923篇 |
2019年 | 16045篇 |
2018年 | 13663篇 |
2016年 | 28260篇 |
2015年 | 20882篇 |
2014年 | 30393篇 |
2013年 | 74282篇 |
2012年 | 37986篇 |
2011年 | 35371篇 |
2010年 | 37716篇 |
2009年 | 40148篇 |
2008年 | 34746篇 |
2007年 | 30552篇 |
2006年 | 35352篇 |
2005年 | 28974篇 |
2004年 | 29740篇 |
2003年 | 27978篇 |
2002年 | 28825篇 |
2001年 | 28582篇 |
2000年 | 24729篇 |
1999年 | 22499篇 |
1998年 | 20944篇 |
1997年 | 20976篇 |
1996年 | 21069篇 |
1995年 | 19146篇 |
1994年 | 18608篇 |
1993年 | 18102篇 |
1992年 | 18311篇 |
1991年 | 18526篇 |
1990年 | 17745篇 |
1989年 | 17808篇 |
1988年 | 17409篇 |
1987年 | 17424篇 |
1986年 | 16290篇 |
1985年 | 22736篇 |
1984年 | 23914篇 |
1983年 | 20051篇 |
1982年 | 21679篇 |
1981年 | 20878篇 |
1980年 | 20251篇 |
1979年 | 20527篇 |
1978年 | 21737篇 |
1977年 | 21411篇 |
1976年 | 21087篇 |
1975年 | 19750篇 |
1974年 | 19415篇 |
1973年 | 19829篇 |
1972年 | 14321篇 |
1967年 | 12621篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Eco‐friendly ionic liquid assisted capillary electrophoresis and α‐acid glycoprotein‐assisted liquid chromatography for simultaneous determination of anticancer drugs in human fluids 下载免费PDF全文
Deia Abd El‐Hady Hassan M. Albishri Rajesh Rengarajan 《Biomedical chromatography : BMC》2015,29(6):925-934
In the current work, two eco‐friendly analytical methods based on capillary electrophoresis (CE) and reversed phase liquid chromatography (RPLC) were developed for simultaneous determination of the most commonly used anticancer drugs for Hodgkin's disease: methotrexate (MTX), vinblastine, chlorambucil and dacarbazine. A background electrolyte (BGE) of 12.5 mmol/L phosphate buffer at pH 7.4 and 0.1 µmol/L 1‐butyl‐3‐methyl imidazolium bromide (BMImBr) ionic liquid (IL) was used for CE measurements at 250 nm detection wavelength, 20 kV applied voltage and 25 °C. The rinsing protocol was significantly improved to reduce the adsorption of IL on the interior surface of capillary. Moreover, RPLC method was developed on α‐1‐acid glycoprotein (AGP) column. Mobile phase was 10 mmol/L phosphate buffer at pH 6.0 (100% v/v) and flow rate at 0.1 mL/min. As AGP is a chiral column, it was successfully separated l ‐MTX from its enantiomer impurity d ‐MTX. Good linearity of quantitative analysis was achieved with coefficients of determinations (r2) >0.995. The stability of drugs measurements was investigated with adequate recoveries up to 24 h storage time under ambient temperature. The limits of detection were <50 and 90 ng/mL by CE and RPLC, respectively. The using of short‐chain IL as an additive in BGE achieved 600‐fold sensitivity enhancement compared with conventional Capillary Zone Electrophoresis (CZE). Therefore, for the first time, the proposed methods were successfully applied to determine simultaneously the analytes in human plasma and urine samples at clinically relevant concentrations with fast and simple pretreatments. Developed IL‐assisted CE and RPLC methods were also applied to measure MTX levels in patients’ samples over time. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
132.
133.
134.
135.
136.
137.
138.
Inside Cover: Ru‐Catalysed CH Arylation of Indoles and Pyrroles with Boronic Acids: Scope and Mechanistic Studies (Chem. Eur. J. 14/2015) 下载免费PDF全文
139.
R. Grosseuvres A. Comandini A. Bentaib N. Chaumeix 《Proceedings of the Combustion Institute》2019,37(2):1537-1546
The present work reports new experimental and numerical results of the combustion properties of hydrogen based mixtures diluted by nitrogen and steam. Spherical expanding flames have been studied in a spherical bomb over a large domain of equivalence ratios, initial temperatures and dilutions at an initial pressure of 100 kPa (Tini = 296, 363, 413 K; N2/O2 = 3.76, 5.67, 9; %Steam = 0, 20, 30). From these experiments, the laminar flame speed , the Markstein length L’, the activation energy Ea and the Zel'dovich β number have been determined. These parameters were also simulated using COSILAB® in order to verify the validity of the Mével et al. [1] detailed kinetic mechanism. Other parameters as the laminar flame thickness δ and the effective Lewis number Leeff were also simulated. These new results aim at providing an extended database that will be very useful in the hydrogen combustion hazard assessment for nuclear reactor power plant new design. 相似文献
140.
Robert G. W. Anderson 《Ambix》2015,62(4):333-344
Following colonisation of South America by the Spanish, many new naturally occurring substances were sent to Europe. One of these was the silvery, unreactive metal, platinum, discovered in New Grenada in the mid-eighteenth century. It was often found in granular form, associated with gold, and the challenge to chemists was to refine it, produce it as wire or sheet, and determine its chemical properties. This interested the professor of chemistry at the University of Edinburgh, Joseph Black, who was able to obtain samples from London-based Spanish contacts, particularly Ignacio Luzuriaga. This paper examines how Black transmitted his knowledge of the metal to large numbers of students attending his annual course. 相似文献