全文获取类型
收费全文 | 8958篇 |
免费 | 395篇 |
国内免费 | 51篇 |
专业分类
化学 | 6325篇 |
晶体学 | 28篇 |
力学 | 270篇 |
数学 | 1520篇 |
物理学 | 1261篇 |
出版年
2021年 | 84篇 |
2020年 | 104篇 |
2019年 | 130篇 |
2018年 | 116篇 |
2017年 | 100篇 |
2016年 | 229篇 |
2015年 | 242篇 |
2014年 | 243篇 |
2013年 | 392篇 |
2012年 | 507篇 |
2011年 | 586篇 |
2010年 | 390篇 |
2009年 | 338篇 |
2008年 | 545篇 |
2007年 | 522篇 |
2006年 | 531篇 |
2005年 | 496篇 |
2004年 | 389篇 |
2003年 | 334篇 |
2002年 | 270篇 |
2001年 | 95篇 |
2000年 | 84篇 |
1999年 | 52篇 |
1998年 | 56篇 |
1997年 | 109篇 |
1996年 | 113篇 |
1995年 | 101篇 |
1994年 | 108篇 |
1993年 | 106篇 |
1992年 | 101篇 |
1991年 | 78篇 |
1990年 | 76篇 |
1989年 | 69篇 |
1988年 | 69篇 |
1987年 | 79篇 |
1986年 | 68篇 |
1985年 | 135篇 |
1984年 | 104篇 |
1983年 | 77篇 |
1982年 | 127篇 |
1981年 | 65篇 |
1980年 | 113篇 |
1979年 | 69篇 |
1978年 | 101篇 |
1977年 | 92篇 |
1976年 | 73篇 |
1975年 | 55篇 |
1974年 | 62篇 |
1973年 | 52篇 |
1972年 | 39篇 |
排序方式: 共有9404条查询结果,搜索用时 109 毫秒
1.
2.
Callant Julien Trufin Julien Zuyderhoff Pierre 《Methodology and Computing in Applied Probability》2022,24(2):595-611
Methodology and Computing in Applied Probability - In this paper, we study a generalized version of the expected time in the red and the expected area in red introduced in Loisel (2005). We derive... 相似文献
3.
This work focuses on interstitial solid solutions of hydrogen in the face-centred cubic (fcc) host lattice of palladium and nickel, using a first-principles based approach. Cluster Variation Method (CVM) and Monte Carlo simulation algorithms were especially designed, allowing a coupled use of both techniques, to study hydrogen–vacancy interactions inside an fcc metallic host lattice. First-principles calculations provided the H–Vac interaction energies by structure inversion method. The phase diagrams and thermodynamic properties were computed using only theoretical inputs. The mechanisms leading to the formation of the miscibility gaps observed for both Pd–H and Ni–H systems and the hydrogen ordering on palladium interstitial lattice were reproduced without any empirical term. 相似文献
4.
Philipp Kulas Martin Seidel Alessandro Bozzato Bernhard Schick Daniel I. Sessler Sascha Kreuer Tobias Hüppe 《Biomedical chromatography : BMC》2020,34(5):e4811
Owing to the lack of specific symptoms, diagnosis of head and neck squamous cell carcinoma (HNSCC) may be delayed. We evaluated volatile organic compounds in tumor samples from patients suffering from HNSCC and tested the hypothesis that there is a characteristic altered composition in the headspace of HNSCC compared with control samples from the same patient with normal squamous epithelium. These results provide the basis for future noninvasive breath analysis in HNSCC. Headspace air of suspected tumor and contralateral control samples in 20 patients were analyzed using ion-mobility spectrometry. Squamous cell carcinoma was diagnosed in 16 patients. In total, we observed 93 different signals in headspace measurements. Squamous cell carcinomas revealed significantly higher levels of volatile cyclohexanol (0.54 ppbv, 25th to 75th percentiles 0.35–0.86) compared with healthy squamous epithelium (0.24 ppbv, 25th to 75th percentiles 0.12–0.3; p < 0.001). In conclusion, head and neck squamous cell carcinoma emitted significantly higher levels of volatile cyclohexanol in headspace compared with normal squamous epithelium. These findings form the basis for future breath analysis for diagnosis, therapy control and the follow-up of HNSSC to improve therapy and aftercare. 相似文献
5.
Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons 下载免费PDF全文
Dr. François Riobé Rózsa Szűcs Dr. Pierre‐Antoine Bouit Dr. Denis Tondelier Bernard Geffroy Fátima Aparicio Julia Buendía Prof. Luis Sánchez Prof. Régis Réau Prof. László Nyulászi Prof. Muriel Hissler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6547-6556
We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs). 相似文献
6.
Naphthalimide‐phthalimide derivative based photoinitiating systems for polymerization reactions under blue lights 下载免费PDF全文
Pu Xiao Frédéric Dumur Jing Zhang Bernadette Graff Didier Gigmes Jean Pierre Fouassier Jacques Lalevée 《Journal of polymer science. Part A, Polymer chemistry》2015,53(5):665-674
Naphthalimide‐phthalimide derivatives (NDPDs) have been synthesized and combined with an iodonium salt, N‐vinylcarbazole, amine or 2,4,6‐tris(trichloromethyl)‐1,3,5‐triazine to produce reactive species (i.e., radicals and cations). These generated reactive species are capable of initiating the cationic polymerization of epoxides and/or the radical polymerization of acrylates upon exposure to very soft polychromatic visible lights or blue lights. Compared with the well‐known camphorquinone based systems used as references, the novel NDPD based combinations employed here demonstrate clearly higher efficiencies for the cationic polymerization of epoxides under air as well as the radical polymerization of acrylates. Remarkably, one of the NDPDs (i.e., NDPD2) based systems is characterized by an outstanding reactivity. The structure/reactivity/efficiency relationships of the investigated NDPDs were studied by fluorescence, cyclic voltammetry, laser flash photolysis, electron spin resonance spin trapping, and steady state photolysis techniques. The key parameters for their reactivity are provided. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 665–674 相似文献
7.
Rational Design and Application of a Redox‐Active,Photoresponsive, Discrete Metallogelator 下载免费PDF全文
Dr. Rouzbeh Afrasiabi Prof. Dr. Heinz‐Bernhard Kraatz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7695-7700
A photoresponsive discrete metallogelator was rationally designed by incorporating a photochromic azobenzene subunit in the structure of a redox‐active ferrocene–peptide conjugate. The target molecule was purposefully equipped with a dipeptide unit capable of self‐assembly in response to sonication. The designed molecule was shown to undergo supramolecular self‐assembly and achieve organogelation in response to ultrasound, light, heat, and redox signals. The sol–gel phase transition of the designed gelator was found to be sensitive to a plethora of input stimuli, allowing the application of the sol–gel transition behavior in basic logic gate operations. A gel‐based NOT logic gate operation was realized when the redox‐active property of the organogel was examined by using different oxidizing agents. The smart response of the gelator was further exploited in designing XOR operations under oxidizing or non‐oxidizing conditions. 相似文献
8.
9.
10.
Pierre Mounoud 《Monatshefte für Mathematik》2015,176(4):603-606