全文获取类型
收费全文 | 202454篇 |
免费 | 3481篇 |
国内免费 | 1270篇 |
专业分类
化学 | 113178篇 |
晶体学 | 3372篇 |
力学 | 8291篇 |
综合类 | 40篇 |
数学 | 19311篇 |
物理学 | 63013篇 |
出版年
2018年 | 1520篇 |
2016年 | 2667篇 |
2015年 | 2077篇 |
2014年 | 2830篇 |
2013年 | 8387篇 |
2012年 | 5993篇 |
2011年 | 7328篇 |
2010年 | 4925篇 |
2009年 | 4821篇 |
2008年 | 6509篇 |
2007年 | 6547篇 |
2006年 | 6329篇 |
2005年 | 5718篇 |
2004年 | 5187篇 |
2003年 | 4621篇 |
2002年 | 4457篇 |
2001年 | 5899篇 |
2000年 | 4520篇 |
1999年 | 3677篇 |
1998年 | 2884篇 |
1997年 | 2894篇 |
1996年 | 2847篇 |
1995年 | 2627篇 |
1994年 | 2483篇 |
1993年 | 2362篇 |
1992年 | 2855篇 |
1991年 | 2734篇 |
1990年 | 2651篇 |
1989年 | 2673篇 |
1988年 | 2610篇 |
1987年 | 2619篇 |
1986年 | 2426篇 |
1985年 | 3285篇 |
1984年 | 3300篇 |
1983年 | 2732篇 |
1982年 | 2916篇 |
1981年 | 2856篇 |
1980年 | 2759篇 |
1979年 | 2896篇 |
1978年 | 3141篇 |
1977年 | 2962篇 |
1976年 | 2903篇 |
1975年 | 2761篇 |
1974年 | 2705篇 |
1973年 | 2722篇 |
1972年 | 1765篇 |
1968年 | 1932篇 |
1967年 | 2129篇 |
1966年 | 1922篇 |
1965年 | 1499篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
João Marcos G. Barbosa Milenna K. Fernandes Rodrigues Lurian C. David Taynara C. e Silva Danielly A. Fortuna Lima Naiara Z. Pereira Emmanuel B. D'Alessandro Anselmo E. de Oliveira Paulo H. Jorge da Cunha Maria Clorinda S. Fioravanti Nelson R. Antoniosi Filho 《Biomedical chromatography : BMC》2020,34(11):e4935
An innovative volatolomic approach employs the detection of biomarkers present in cerumen (earwax) to identify cattle intoxication by Stryphnodendron rotundifolium Mart., Fabaceae (popularly known as barbatimão). S. rotundifolium is a poisonous plant with the toxic compound undefined and widely distributed throughout the Brazilian territory. Cerumen samples from cattle of two local Brazilian breeds (‘Curraleiro Pé-Duro’ and ‘Pantaneiro’) were collected during an experimental intoxication protocol and analyzed using headspace (HS)/GC–MS followed by multivariate analysis (genetic algorithm for a partial least squares, cluster analysis, and classification and regression trees). A total of 106 volatile organic metabolites were identified in the cerumen samples of bovines. The intoxication by S. rotundifolium influenced the cerumen volatolomic profile of the bovines throughout the intoxication protocol. In this way, it was possible to detect biomarkers for cattle intoxication. Among the biomarkers, 2-octyldecanol and 9-tetradecen-1-ol were able to discriminate all samples between intoxicated and nonintoxicated bovines. The cattle intoxication diagnosis by S. rotundifolium was accomplished by applying the cerumen analysis using HS/GC–MS, in an easy, accurate, and noninvasive way. Thus, the proposed bioanalytical chromatography protocol is a useful tool in veterinary applications to determine this kind of intoxication. 相似文献
52.
Jia Yang Xingang Li Wenjun Li Xin Xi Qian Du Feng Pan Songqing Liu 《Biomedical chromatography : BMC》2020,34(8):e4857
Because of its unpredictable side effects and efficacy, the anticancer drug docetaxel (DTX) requires improved characterisation of its pharmacokinetic profiles through population pharmacokinetic studies. A sensitive and rugged LC–MS/MS method for the detection of DTX in human plasma was developed and optimised using paclitaxel as an internal standard (IS). The plasma samples underwent rapid extraction using hybrid solid-phase extraction-protein precipitation. The analyte and IS were separated with an isocratic system on a Zorbax Eclipse Plus C18 column using water containing 0.05% acetic acid along with 20 μM of sodium acetate and methanol (30/70, v/v) as the mobile phase. Quantification was performed using a triple quadrupole mass spectrometer through multiple reaction monitoring in positive mode, using the m/z 830.3 → 548.8 and m/z 876.3 → 307.7 transitions for DTX and paclitaxel, respectively. The range of the calibration curve was 1–500 ng/mL for DTX, and the linear correlation coefficient was >0.99. The accuracies ranged from −4.6 to 4.2%, and the precision was no higher than 7.0% for the analytes. No significant matrix effect was observed. Both DTX and the IS showed considerable recovery. This method was finally applied to the establishment of a population pharmacokinetic model to optimise the clinical use of DTX. 相似文献
53.
We numerically solve the time-dependent Ginzburg–Landau equations for two-gap superconductors using the finite-element technique. The real-time simulation shows that at low magnetic field, the vortices in small-size samples tend to form clusters or other disorder structures. When the sample size is large, stripes appear in the pattern. These results are in good agreement with the previous experimental observations of the intriguing anomalous vortex pattern, providing a reliable theoretical basis for the future applications of multi-gap superconductors. 相似文献
54.
55.
56.
57.
58.
59.
Briana L. Simms Nan Ji Indika Chandrasiri Mohammad Farid Zia Chinwe S. Udemgba Ravinder Kaur Jared H. Delcamp Alex Flynt Chalet Tan Davita L. Watkins 《Journal of polymer science. Part A, Polymer chemistry》2021,59(19):2177-2192
Here, we demonstrate the applicability of self-assembling linear-dendritic block copolymers (LDBCs) and their nanoaggregates possessing varied surfaces as therapeutic nanocarriers. These LDBCs are comprised of a hydrophobic, linear polyester chemically coupled to a hydrophilic dendron polyamidoamine (PAMAM)—the latter of which acts as the surface of the self-assembled nanoaggregate in aqueous media. To better understand how surface charge density affects the overall operability of these nanomaterials, we modified the nanoaggregate surface to yield cationic (NH3+), neutral (OH), and anionic (COO−) surfaces. The effect of these modifications on the physicochemical properties (i.e., size, morphology, and surface charge density), colloidal stability, and cellular uptake mechanism of the polymeric nanocarrier were investigated. This comparative study demonstrates the viability of nanoaggregates formed from PDLLA-PAMAM LDBCs to serve as nanocarriers for applications in drug delivery. 相似文献
60.