全文获取类型
收费全文 | 1378篇 |
免费 | 46篇 |
国内免费 | 5篇 |
专业分类
化学 | 895篇 |
晶体学 | 8篇 |
力学 | 17篇 |
数学 | 199篇 |
物理学 | 310篇 |
出版年
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 30篇 |
2020年 | 28篇 |
2019年 | 23篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 46篇 |
2015年 | 30篇 |
2014年 | 41篇 |
2013年 | 61篇 |
2012年 | 68篇 |
2011年 | 92篇 |
2010年 | 49篇 |
2009年 | 47篇 |
2008年 | 62篇 |
2007年 | 82篇 |
2006年 | 88篇 |
2005年 | 52篇 |
2004年 | 62篇 |
2003年 | 30篇 |
2002年 | 26篇 |
2001年 | 23篇 |
2000年 | 14篇 |
1999年 | 20篇 |
1998年 | 24篇 |
1997年 | 13篇 |
1996年 | 20篇 |
1995年 | 17篇 |
1994年 | 16篇 |
1993年 | 16篇 |
1992年 | 13篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 17篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 23篇 |
1983年 | 11篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 18篇 |
1979年 | 9篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1975年 | 9篇 |
1974年 | 12篇 |
1972年 | 9篇 |
排序方式: 共有1429条查询结果,搜索用时 15 毫秒
61.
Malik Salman Haider Jochen Schreiner Sabine Kendl Matthias Kroiss Robert Luxenhofer 《Macromolecular bioscience》2020,20(1)
Adrenocortical carcinoma (ACC) is a rare tumor and prognosis is overall poor but heterogeneous. Mitotane (MT) has been used for treatment of ACC for decades, either alone or in combination with cytotoxic chemotherapy. Even at doses up to 6 g per day, more than half of the patients do not achieve targeted plasma concentration (14–20 mg L?1) even after many months of treatment due to low water solubility, bioavailability, and unfavorable pharmacokinetic profile. Here a novel MT nanoformulation with very high MT concentrations in physiological aqueous media is reported. The MT‐loaded nanoformulations are characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and powder X‐ray diffraction which confirms the amorphous nature of the drug. The polymer itself does not show any cytotoxicity in adrenal and liver cell lines. By using the ACC model cell line NCI‐H295 both in monolayers and tumor cell spheroids, micellar MT is demonstrated to exhibit comparable efficacy to its ethanol solution. It is postulated that this formulation will be suitable for i.v. application and rapid attainment of therapeutic plasma concentrations. In conclusion, the micellar formulation is considered a promising tool to alleviate major drawbacks of current MT treatment while retaining bioactivity toward ACC in vitro. 相似文献
62.
Jochen Szangolies 《Foundations of Physics》2018,48(12):1669-1697
In-principle restrictions on the amount of information that can be gathered about a system have been proposed as a foundational principle in several recent reconstructions of the formalism of quantum mechanics. However, it seems unclear precisely why one should be thus restricted. We investigate the notion of paradoxical self-reference as a possible origin of such epistemic horizons by means of a fixed-point theorem in Cartesian closed categories due to Lawvere that illuminates and unifies the different perspectives on self-reference. 相似文献
63.
H W Strube 《The Journal of the Acoustical Society of America》1986,79(5):1511-1518
If the level behavior of the cubic difference tone is explained by a static nonlinear characteristic, the correspondence between this characteristic and certain components and quantities of the basilar membrane must be clarified. This is attempted here for a nonlinearity compatible with the idea of an active undamping feedback mechanism saturating at high levels. The relation between asymptotic behavior of the nonlinearity and the measured CDT level dependence is established. Agreement with psychoacoustic data requires a very "softly" compressing characteristic; linear or logarithmic asymptotes are ruled out. The psychoacoustically known level dependence is well reproduced for small primary-frequency differences by cancellation experiments with a digitally simulated basilar-membrane model. 相似文献
64.
Jochen Kripfganz Andreas Laser Michael G. Schmidt 《Zeitschrift fur Physik C Particles and Fields》1997,73(2):353-362
The main perturbative contribution to the free energy of an electroweak interface is due to the effective potential and the tree level kinetic term. The derivative corrections are investigated with one-loop perturbation theory. The action is treated in derivative, in heat kernel, and in a multi local expansion. The massive contributions turn out to be well described by the Z-factor. The massless mode, plagued by infrared problems, is numerically less important. Its perturbatively reliable part can by calculated in derivative expansion as well. A self consistent way to include the Z-factor in the formula for the interface tension is presented. 相似文献
65.
66.
We study the two-flavor quark-meson (QM) model with the functional renormalization group (FRG) to describe the effects of collective mesonic fluctuations on the phase diagram of QCD at finite baryon and isospin chemical potentials, μB and μI. With only isospin chemical potential there is a precise equivalence between the competing dynamics of chiral versus pion condensation and that of collective mesonic and baryonic fluctuations in the quark-meson-diquark model for two-color QCD at finite baryon chemical potential. Here, finite μB=3μ introduces an additional dimension to the phase diagram as compared to two-color QCD, however. At zero temperature, the (μI,μ) plane of this phase diagram is strongly constrained by the “Silver Blaze problem.” In particular, the onset of pion condensation must occur at μI=mπ/2, independent of μ as long as μ+μI stays below the constituent quark mass of the QM model or the liquid-gas transition line of nuclear matter in QCD. In order to maintain this relation beyond mean field it is crucial to compute the pion mass from its timelike correlator with the FRG in a consistent way. 相似文献
67.
Nanotextured multicrystalline Al‐BSF solar cells reaching 18% conversion efficiency using industrially viable solar cell processes 下载免费PDF全文
Bishal Kafle Abdul Mannan Timo Freund Laurent Clochard Edward Duffy Marc Hofmann Jochen Rentsch Ralf Preu 《固体物理学:研究快报》2015,9(8):448-452
We report recent achievements in adapting industrially used solar cell processes on nanotextured surfaces. Nanostructures were etched into c‐Si surfaces by dry exothermic plasma‐less reaction of F species with Si in atmospheric pressure conditions and then modified using a short post‐etching process. Nanotextured multicrystalline wafers are used to prepare Al‐BSF solar cells using industrially feasible solar cell proc‐ essing steps. In comparison to the reference acidic textured solar cells, the nanostructured cells showed gain in short circuit current (Jsc) of up to 0.8 mA/cm2 and absolute gain in conversion efficiency of up to 0.3%. The best nanotextured solar cell was independently certified to reach the conversion efficiency of 18.0%. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
68.
69.
We give an explicit formula for the number of nodal domains of certain eigenfunctions on a flat torus. We apply this to an
isospectral but not isometric family of pairs of flat four-dimensional tori constructed by Conway and Sloane, and we show
that corresponding eigenfunctions have the same number of nodal domains. This disproves a conjecture by Brüning, Gnutzmann,
and Smilansky. 相似文献
70.
Jochen Münchenberg Jens R. Goerlich Axel K. Fischer Peter G. Jones Reinhard Schmutzler 《无机化学与普通化学杂志》1996,622(2):348-354
Synthesis, Structure, and some Reactions of N-(N′,N′,N″,N″-tetramethyl)guanidinyl-substituted Phosphoryl Compounds The tetramethylguanidinyl-substituted phosphoryl compounds 1 – 10 were prepared in the reaction of the appropriate chlorophosphoryl compounds with either N′,N′,N″,N″-tetramethylguanidine (HTMG) or N-trimethylsilyl-(N′,N′,N″,N″-tetramethyl)guanidine (TMSTMG). With methyl iodide 1 reacted with N-alkylation to give the ammonium salt 11. 1 reacted with BF3 · Et2O at both imino nitrogen atoms with formation of the bis-BF3-adduct 12 . The X-ray structure determination of phenylphosphonic acid-bis(N′,N′,N″,N″-tetramethylguanidinide) 3 shows shortened PN-bonds and widened PNC-angles, consistent with the partial double bond character of the PN-bond. 相似文献