全文获取类型
收费全文 | 1239篇 |
免费 | 51篇 |
国内免费 | 20篇 |
专业分类
化学 | 667篇 |
晶体学 | 3篇 |
力学 | 59篇 |
数学 | 357篇 |
物理学 | 224篇 |
出版年
2023年 | 11篇 |
2022年 | 41篇 |
2021年 | 46篇 |
2020年 | 52篇 |
2019年 | 47篇 |
2018年 | 54篇 |
2017年 | 42篇 |
2016年 | 64篇 |
2015年 | 28篇 |
2014年 | 53篇 |
2013年 | 97篇 |
2012年 | 68篇 |
2011年 | 65篇 |
2010年 | 49篇 |
2009年 | 36篇 |
2008年 | 65篇 |
2007年 | 56篇 |
2006年 | 33篇 |
2005年 | 33篇 |
2004年 | 37篇 |
2003年 | 20篇 |
2002年 | 26篇 |
2001年 | 7篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 10篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1976年 | 7篇 |
1975年 | 10篇 |
1974年 | 5篇 |
1972年 | 4篇 |
排序方式: 共有1310条查询结果,搜索用时 31 毫秒
51.
Ly Dieu Ha Poul Erik Hansen Fritz Duus Hung Dinh Pham Lien‐Hoa D. Nguyen 《Magnetic resonance in chemistry : MRC》2012,50(3):242-245
Four new prenylated depsidones, oliveridepsidones A–D, were isolated from the bark of Garcinia oliveri collected in Vietnam. Their structures were elucidated using mainly NMR techniques (1H and 13C NMR, HMQC, HMBC and NOE experiments). Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
52.
53.
In this paper, we introduce a splitting algorithm for solving equilibrium problems given by the difference of two bifunctions in a real Hilbert space. Under suitable assumptions on component bifunctions, we prove strong convergence of the proposed algorithm. In contrast to most existing projection-type methods for equilibrium problems, our algorithm does not require any convexity or monotonicity conditions on the resulting bifunction. Some numerical experiments and comparisons are given to illustrate the efficiency of the proposed algorithm. 相似文献
54.
55.
56.
Numerical Algorithms - In this paper, we introduce a self-adaptive inertial gradient projection algorithm for solving monotone or strongly pseudomonotone variational inequalities in real Hilbert... 相似文献
57.
Ho Van Doanh Phan Bao Quoc Hieu Pham Ngoc Son Dao Van Hoang Tam Hoang Duc Ho Manh Dung 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(3):1361-1365
Journal of Radioanalytical and Nuclear Chemistry - To keep the accredited category for the gamma spectrometry test in our laboratory, the efficiency curves of a HPGe detector for soil sample in... 相似文献
58.
Pham Duy Khanh Tran Hong Mo Trinh T. T. Tran 《Numerical Functional Analysis & Optimization》2019,40(8):924-943
Necessary and sufficient conditions for qualitative properties of infinite dimensional linear programing problems such as solvability, duality, and complementary slackness conditions are studied in this article. As illustrations for the results, we investigate the parametric version of Gale’s example. 相似文献
59.
A solid state-based method using a hot reaction chamber is applied to the synthesis of Y2O3:Eu particles containing Eu from 0 to 5 mol%. The produced powders are studied using X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM), as well as photoluminescence (PL) and radioluminescence tests. TEM and XRD results revealed the powder to be mono-disperse and in the form of a solid solution. The PL of Y2O3:Eu powder depends on both the concentration quenching effect (due to an excess of Eu concentration) and the surface luminescence effect (depicted by a higher surface area induced by the large phosphor concentration in the solution or smaller particle sizes). A 22Na gamma source is used to compare the recorded count rates for four Y2O3:Eu scintillator materials with different concentrations of Eu. Each scintillator composition is examined in four forms: solid pellets with a high volume porosity and three aqueous solutions of Y2O3:Eu particles of the different scintillator materials at concentrations of 25, 50 and 100 mg/mL. The radioluminescence results indicated that increasing the transparency and/or the amount of Eu mol% of the scintillators increases the net average counts. 相似文献
60.
Thanh Duc Mai Benjamin Bomastyk Hong Anh Duong Hung Viet Pham Peter C. Hauser 《Analytica chimica acta》2012
An extension of a capillary electrophoresis instrument coupled to a sequential injection analysis manifold was developed for automated measurements with on-line solid-phase extraction preconcentration. An in-house built capacitively coupled contactless conductivity detector was employed for sensitive detection with narrow capillaries of 25 μm internal diameter. The system was assembled into standardized 19 in. frames and racks for easy transport and mobile deployment. The system can be left running unattendedly without manual intervention with good operation stability. To demonstrate the application of the system, a method for the determination of four drugs, namely ibuprofen, diclofenac, naproxen and bezafibrate, was developed with enrichment factors of up to several hundreds. Detection of the drug residues down to the nM-scale was found possible and the method was found suitable for the detection of ibuprofen in the waste water of a hospital in Hanoi. 相似文献