全文获取类型
收费全文 | 10998篇 |
免费 | 1921篇 |
国内免费 | 1664篇 |
专业分类
化学 | 8550篇 |
晶体学 | 156篇 |
力学 | 660篇 |
综合类 | 105篇 |
数学 | 1415篇 |
物理学 | 3697篇 |
出版年
2024年 | 26篇 |
2023年 | 169篇 |
2022年 | 351篇 |
2021年 | 403篇 |
2020年 | 407篇 |
2019年 | 470篇 |
2018年 | 383篇 |
2017年 | 343篇 |
2016年 | 556篇 |
2015年 | 646篇 |
2014年 | 658篇 |
2013年 | 817篇 |
2012年 | 944篇 |
2011年 | 940篇 |
2010年 | 768篇 |
2009年 | 729篇 |
2008年 | 765篇 |
2007年 | 628篇 |
2006年 | 557篇 |
2005年 | 517篇 |
2004年 | 476篇 |
2003年 | 440篇 |
2002年 | 543篇 |
2001年 | 438篇 |
2000年 | 290篇 |
1999年 | 231篇 |
1998年 | 201篇 |
1997年 | 139篇 |
1996年 | 129篇 |
1995年 | 116篇 |
1994年 | 90篇 |
1993年 | 70篇 |
1992年 | 57篇 |
1991年 | 60篇 |
1990年 | 40篇 |
1989年 | 29篇 |
1988年 | 24篇 |
1987年 | 19篇 |
1986年 | 11篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 34 毫秒
101.
Wen‐ming He 《Numerical Methods for Partial Differential Equations》2019,35(6):2044-2055
In this article, we will discuss the local ultraconvergence of high‐degree finite element method based on a rectangular partition for the second‐degree elliptic problem with constant coefficients in Ω ? ?2 , u( y ) = 0 on ?Ω . Based on suitable regularity, ultraconvergence of the displacement of the extrapolated kth (k ≥ 3) degree finite element solution has been obtained by an extrapolation technique. Finally, numerical experiments are applied to demonstrate our theoretical findings. 相似文献
102.
103.
We study the interpolation of Morrey-Campanato spaces and some smoothness spaces based on Morrey spaces, e. g., Besov-type and Triebel-Lizorkin-type spaces. Various interpolation methods, including the complex method, the ±-method and the Peetre-Gagliardo method, are studied in such a framework. Special emphasis is given to the quasi-Banach case and to the interpolation property. 相似文献
104.
Bei Zhou Yousef Heider Andreas Blaeser Stefan Raith Horst Fischer Bernd Markert 《PAMM》2016,16(1):117-118
The aim of this work is to numerically simulate the gelation of a crosslinking polymer, which is a very complex process involving chemical reactions and phase transitions from a viscous fluid to a viscoelastic solid. A phenomenological model is proposed to simulate the gelation process of agarose droplets, considering the thermal boundary conditions. The numerical model is implemented using the finite element package FlexPDE. The temperature- and time-dependent degree of gelation and the deformation of the droplets during the gelation process are investigated. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
105.
Angela Niedermeyer Bei Zhou Gözde Dursun Marcus Stoffel Aysegül Artmann Bernd Markert 《PAMM》2016,16(1):99-100
Replacement tissues, designed to fill in articular cartilage defects, should exhibit the same properties as the native material. The aim of this study is to foster the understanding of, firstly, the mechanical behavior of the material itself and, secondly, the influence of cultivation parameters on cell seeded implants as well as on cell migration into acellular implants. In this study, acellular cartilage replacement material is theoretically, numerically and experimentally investigated regarding its viscoelastic properties, where a phenomenological model for practical applications is developed. Furthermore, remodeling and cell migration are investigated. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
106.
Lipid profiling of human plasma from peritoneal dialysis patients using an improved 2D (NP/RP) LC-QToF MS method 总被引:1,自引:0,他引:1
Min Li Baosheng Feng Yuan Liang Wei Zhang Yu Bai Wen Tang Tao Wang Huwei Liu 《Analytical and bioanalytical chemistry》2013,405(21):6629-6638
An improved online two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry (2D LC-QToF MS) system was developed for the lipid profiling of human plasma, in which different lipid classes were separated by the first dimensional normal-phase (NP) LC and different lipid molecular species were separated by the second dimensional reversed-phase (RP) LC. This 2D LC-QToF MS system was built based on a ten-port, two-position valve as the interface, the conditions of which had been optimized and discussed in detail. As two loops were used to trap and transfer the first dimensional elute to the second dimension separately, this new interface suppressed the sample band broadening in the first dimensional column, increased the recovery and repeatability of 2D LC interface, and offered the possibility for the realization of not-stop-flow NP/RP 2D LC system. Finally, 190 endogenous lipid species out of 10 lipid classes were determined within a single run from the plasma of peritoneal patients. This method was also applied to identify the difference in lipid profile between plasma from peritoneal dialysis patients with bad volume status and peritoneal dialysis patients with good volume status. The discovery of 30 potential biomarkers would be helpful to the malnutrition, inflammation, and atherosclerosis syndrome investigation. 相似文献
107.
Wenxue Li Jun Wen Jingyu He Di Cao Fanlu Sun Jinying Li Guorong Fan 《Journal of separation science》2013,36(19):3184-3190
A simple, rapid, high‐throughput, and highly sensitive LC–MS/MS was developed to determine anisodamine in a small volume (50 μL) of beagle dog plasma using atropine sulfate as the internal standard. The analyte and internal standard were isolated from 50 μL plasma samples after a one‐step protein precipitation using Sirocco 96‐well protein precipitation filtration plates. The separation was accomplished on a Hanbon Hedera CN column (100 × 4.6 mm, 5 μm) and the run time was 4 min. A Micromass Quatro Ultima mass spectrometer equipped with an ESI source was operated in the multiple reaction monitoring mode with the precursor‐to‐product ion transitions m/z 306.0→140.0 (anisodamine) and 290.0→123.9 (atropine) used for quantitation. The method was sensitive with a low LOQ of 0.05 ng/mL, and good linearity in the range 0.05–50 ng/mL for anisodamine (r2 ≥ 0.995). All the validation data, such as accuracy, intra‐ and interrun precision, were within the required limits. The method was successfully applied to the pharmacokinetic study of anisodamine hydrochloride injection in beagle dogs. 相似文献
108.
Bei‐Bei Zhang Qian Jiang Zhi‐Xin Liao Chao Liu Shi‐Jun Liu 《Helvetica chimica acta》2013,96(7):1281-1289
Phytochemical investigation of the EtOH extract of Euphorbia sieboldiana led to the isolation of four new oleanane‐type triterpenoids, (1β,2α,3β,19β)‐1,2,3,19‐tetrahydroxyolean‐12‐en‐28‐oic acid, (1β,3β,19β)‐1,3,19‐trihydroxyolean‐12‐en‐28‐oic acid, (1β,2α,3β,16β,19β)‐1,2,3,16,19‐pentahydroxyolean‐12‐en‐28‐oic acid, and (1β,2α,3β,19β,23)‐1,2,3,19,23‐pentahydroxyolean‐12‐en‐28‐oic acid, along with 16 known compounds. Their structures were established by extensive 1D‐ and 2D‐NMR, as well as other spectral analyses. Biological evaluation of the four new triterpenoids revealed potent cytotoxic activities against HeLa and Hep‐G2 cells. 相似文献
109.
110.