全文获取类型
收费全文 | 2200篇 |
免费 | 80篇 |
国内免费 | 12篇 |
专业分类
化学 | 1738篇 |
晶体学 | 30篇 |
力学 | 13篇 |
数学 | 94篇 |
物理学 | 417篇 |
出版年
2021年 | 14篇 |
2020年 | 16篇 |
2019年 | 19篇 |
2018年 | 12篇 |
2017年 | 20篇 |
2016年 | 41篇 |
2015年 | 43篇 |
2014年 | 58篇 |
2013年 | 86篇 |
2012年 | 79篇 |
2011年 | 129篇 |
2010年 | 63篇 |
2009年 | 81篇 |
2008年 | 105篇 |
2007年 | 120篇 |
2006年 | 119篇 |
2005年 | 111篇 |
2004年 | 121篇 |
2003年 | 86篇 |
2002年 | 94篇 |
2001年 | 48篇 |
2000年 | 51篇 |
1999年 | 43篇 |
1998年 | 20篇 |
1997年 | 36篇 |
1996年 | 33篇 |
1995年 | 19篇 |
1994年 | 29篇 |
1993年 | 21篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 25篇 |
1989年 | 24篇 |
1988年 | 28篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 20篇 |
1984年 | 36篇 |
1983年 | 22篇 |
1982年 | 31篇 |
1981年 | 25篇 |
1980年 | 32篇 |
1979年 | 42篇 |
1978年 | 33篇 |
1977年 | 25篇 |
1976年 | 32篇 |
1975年 | 17篇 |
1974年 | 21篇 |
1973年 | 13篇 |
1968年 | 9篇 |
排序方式: 共有2292条查询结果,搜索用时 203 毫秒
1.
2.
Hiroto Kudo Nobuhito Ito Keiji Nakajima Masami Ochiai Tadatomi Nishikubo 《Journal of polymer science. Part A, Polymer chemistry》2007,45(19):4421-4429
The polyaddition of fluorine‐containing bis(epoxide)s and fluorine‐containing triazine di(aryl ether)s were examined to give the corresponding fluorine‐containing poly(cyanurate)s. It was observed that the synthesized fluoropolymers had good thermal stabilities and good film‐forming properties. The glass transition temperatures (Tg's) and refractive‐indices (nD's) of synthesized polymers were determined by differential scanning calorimetry and ellipsometry, respectively, and it was found that the values of Tg's and nD's were supported by their fluorine containing ratios and skeletons. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4421–4429, 2007 相似文献
3.
Application of the 19F NMR technique to observe binding of the general anesthetic halothane to human serum albumin. 总被引:1,自引:0,他引:1
Kazuaki Shikii Satoshi Sakurai Hiroaki Utsumi Hiroko Seki Mitsuru Tashiro 《Analytical sciences》2004,20(10):1475-1477
19F NMR techniques were employed to characterize the binding property of the widely used general anesthetic halothane with human serum albumin (HSA). It was found that 19F(1H) NOE and 2D 1H-19F HOESY experiments detected intermolecular NOEs between halothane 19F and HSA protons. Measurements of the diffusion coefficients for halothane were also carried out by 1H and 19F NMR, indicating the interaction of halothane with HSA. The present results indicate that these techniques are very suitable to identify a fluorine-containing ligand binding with a protein receptor in the drug-discovery process. 相似文献
4.
In order to change the ion-exchange selectivity of anion-exchange resin, the surface of a gel-type anion exchange resin was modified with anionic polyelectrolyte, polystyrenesulfonic acid. Using this modified resin, the ion-exchange rate of nitrate was little decreased, but that of sulfate was evidently decreased. It is considered that the ion-exchange reaction of the multivalent anion is suppressed by the greater electrostatic repulsive force against the modification layer than that against the monovalent anion. Thus, this modified resin may be suitable for the selective separation of monovalent anions. The influence of the modified condition on the ion-exchange rate was examined. Furthermore, this modified resin was used to separate nitrate ions from sulfate ions in the aqueous solution. 相似文献
5.
The running coupling and the Kugo-Ojima parameter of unquenched lattice Landau gauge are simulated and compared with the continuum
theory. Although the running coupling measured by the ghost and gluon dressing function is infrared suppressed, the running
coupling has a maximum of α0 ∼ 2 − 2.5 at around q = 0.5 GeV irrespective of the fermion actions (Wilson fermions and Kogut-Susskind (KS) fermions). The Kugo-Ojima parameter
c which saturated to about 0.8 in quenched simulations becomes consistent with 1 in the MILC configurations produced with the
use of the Asqtad action, after averaging the dependence on polarization directions caused by the asymmetry of the lattice.
The presence of the correction factor 1 + c
1/q
2 in the running coupling depends on the lattice size and the sea quark mass. In the large lattice size and small sea quark
mass, c
1 is confirmed of the order of a few GeV. The MILC configuration of a = 0.09 fm suggests also the presence of dimension-4 condensates with a sign opposite to the dimension-2 condensates. The
gluon propagator, the ghost propagator, and the running coupling are compared with recent pQCD results including an anomalous
dimension of fields up to the four-loop level. 相似文献
6.
7.
Trifluoromethylation onto the tetrafluorophthalonitrile and tetrafluoroisophthalonitrile has been carried out using CF3TMS-CuI-KF system, and it was demonstrated that these trifluoromethylation enabled us to successfully construct di- and/or tri-trifluoromethylated benzonitriles via the decyanotrifluoromethylation. 相似文献
8.
A high-speed and economical optical local access network system is proposed where bi-directional polarization multiplexing is applied to a bi-directional transmission. Experimental results using a prototype system confirmlow optical loss and environmental stabilities. 相似文献
9.
We have investigated the photoluminescence (PL) properties of trace amounts of Pr and Tb in single-crystal samples of yttria-stabilized zironia (YSZ), and found that Pr of the order of 10−6 mass% and Tb of the order of 10−5 mass% in YSZ can be detected by the PL spectroscopy. The PL spectra of the YSZ samples for the 280 nm excitation were comprised of several peaks and a broad emission. The peaks were attributed to transitions of Pr3+ and Tb3+ in the YSZ samples, whereas the broad emission seemed to be attributed to the yttria-associated oxygen vacancies. The peak intensities corresponded to the amounts of Pr and Tb in the YSZ samples, the amounts of which were analyzed by glow discharge mass spectrometry. In the PL excitation spectra, but not in the photoabsorption spectra, small peaks at 376 and 381 nm were observed, and were attributed to the transitions of Tb3+ in the YSZ samples. The results of the PL excitation spectra corresponding to the Pr3+ line emissions suggest that the charge transfer occurs between the YSZ and Pr ion in it. The trace amounts of these lanthanoids in YSZ would disturb the decay process of the photoinduced electrons to the yttria-associated oxygen vacancies. 相似文献
10.