全文获取类型
收费全文 | 209058篇 |
免费 | 2464篇 |
国内免费 | 519篇 |
专业分类
化学 | 114909篇 |
晶体学 | 3737篇 |
力学 | 8191篇 |
综合类 | 11篇 |
数学 | 19805篇 |
物理学 | 65388篇 |
出版年
2020年 | 1887篇 |
2019年 | 2129篇 |
2018年 | 2420篇 |
2017年 | 2539篇 |
2016年 | 3761篇 |
2015年 | 2364篇 |
2014年 | 3871篇 |
2013年 | 9634篇 |
2012年 | 6927篇 |
2011年 | 8494篇 |
2010年 | 5980篇 |
2009年 | 5935篇 |
2008年 | 7482篇 |
2007年 | 7370篇 |
2006年 | 6941篇 |
2005年 | 6247篇 |
2004年 | 5670篇 |
2003年 | 5211篇 |
2002年 | 4982篇 |
2001年 | 6207篇 |
2000年 | 4707篇 |
1999年 | 3565篇 |
1998年 | 2778篇 |
1997年 | 2734篇 |
1996年 | 2655篇 |
1995年 | 2508篇 |
1994年 | 2397篇 |
1993年 | 2241篇 |
1992年 | 2913篇 |
1991年 | 2791篇 |
1990年 | 2721篇 |
1989年 | 2743篇 |
1988年 | 2768篇 |
1987年 | 2775篇 |
1986年 | 2635篇 |
1985年 | 3372篇 |
1984年 | 3382篇 |
1983年 | 2650篇 |
1982年 | 2768篇 |
1981年 | 2834篇 |
1980年 | 2600篇 |
1979年 | 2935篇 |
1978年 | 2935篇 |
1977年 | 3040篇 |
1976年 | 2859篇 |
1975年 | 2598篇 |
1974年 | 2563篇 |
1973年 | 2505篇 |
1972年 | 1739篇 |
1968年 | 1711篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Saleh Z. M. Nasser H. Özkol E. Günöven M. Abak K. Canli S. Bek A. Turan R. 《Journal of nanoparticle research》2015,17(10):1-12
Journal of Nanoparticle Research - Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100&;nbsp;nm) have been processed by the self-assembled dewetting... 相似文献
22.
JETP Letters - Relatively low crossover temperature suggests that chiral symmetry restoration in Quantum Chromodynamics may well be described within the low-energy effective theory. The shape of... 相似文献
23.
K.M.J. Rocha R.G. Leitão E.G. Oliveira-Barros M.A. Oliveira C.G.L. Canellas M.J. Anjos L.E. Nasciutti R.T. Lopes 《X射线光谱测定》2019,48(5):476-481
Prostate cancer is a highly prevalent disease and ranks second among malignant neoplasms that affect men around the world, behind lung cancer alone. Trace elements are very important and are involved in many cellular processes. The X-ray microfluorescence technique is an advanced tool of high spatial resolution, sensitivity, multielemental analysis, and nondestructiveness for trace element study. This study aimed to investigate the elemental distribution in spheroids obtained through the following human prostate cell lines using synchrotron X-ray microfluorescence: tumor cell line androgen independent (DU145), tumor cell line androgen dependent (LNCaP), and normal cell line (RWPE-1). The measurements were performed with a standard geometry of 45° of incidence, excited by a white beam using a pixel of 25 μm and an acquisition time of 300 ms/pixel at the X-ray fluorescence beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). The synchrotron X-ray microfluorescence results showed differences between groups in all elements analyzed and suggested that further studies should be performed to understand the relationship of these trace elements with the progression and development of the disease. 相似文献
24.
Development and validation of a reversed‐phase HPLC method for CYP1A2 phenotyping by use of a caffeine metabolite ratio in saliva 下载免费PDF全文
Elias Begas Evangelos Kouvaras Andreas K. Tsakalof Maria Bounitsi Eftihia Konstadinos Asprodini 《Biomedical chromatography : BMC》2015,29(11):1657-1663
CYP1A2 is important for metabolizing various clinically used drugs. Phenotyping of CYP1A2 may prove helpful for drug individualization therapy. Several HPLC methods have been developed for quantification of caffeine metabolites in plasma and urine. Aim of the present study was to develop a valid and simple HPLC method for evaluating CYP1A2 activity during exposure in xenobiotics by the use of human saliva. Caffeine and paraxanthine were isolated from saliva by liquid‐liquid extraction (chlorophorm/isopropanol 85/15v/v). Extracts were analyzed by reversed‐phase HPLC on a C18 column with mobile phase 0.1% acetic acid/methanol/acetonitrile (80/20/2 v/v) and detected at 273nm. Caffeine and paraxanthine elution times were <13min with no interferences from impurities or caffeine metabolites. Detector response was linear (0.10–8.00µg/ml, R2>0.99), recovery was >93% and bias <4.47%. Intra‐ and inter‐day precision was <5.14% (n=6). The limit of quantitation was 0.10µg/ml and the limit of detection was 0.018±0.002µg/mL for paraxanthine and 0.032±0.002µg/ml for caffeine. Paraxanthine/caffeine ratio of 34 healthy volunteers was significantly higher in smokers (p<0.001). Saliva paraxanthine/caffeine ratios and urine metabolite ratios were highly correlated (r=0.85, p<0.001). The method can be used for the monitoring of CYP1A2 activity in clinical practice and in studies relevant to exposure to environmental and pharmacological xenobiotics. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
25.
Ivanov K. A. Gubaidullin A. R. Morozov K. M. Sasin M. E. Kaliteevskii M. A. 《Optics and Spectroscopy》2019,126(6):787-787
Optics and Spectroscopy - 10.1134/S0030400X17050095 相似文献
26.
27.
28.
29.
30.