全文获取类型
收费全文 | 1014篇 |
免费 | 29篇 |
国内免费 | 3篇 |
专业分类
化学 | 739篇 |
晶体学 | 9篇 |
力学 | 13篇 |
综合类 | 1篇 |
数学 | 35篇 |
物理学 | 249篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 15篇 |
2019年 | 17篇 |
2018年 | 8篇 |
2016年 | 13篇 |
2015年 | 15篇 |
2014年 | 17篇 |
2013年 | 51篇 |
2012年 | 51篇 |
2011年 | 37篇 |
2010年 | 32篇 |
2009年 | 23篇 |
2008年 | 50篇 |
2007年 | 47篇 |
2006年 | 60篇 |
2005年 | 52篇 |
2004年 | 46篇 |
2003年 | 40篇 |
2002年 | 44篇 |
2001年 | 32篇 |
2000年 | 35篇 |
1999年 | 26篇 |
1998年 | 14篇 |
1997年 | 8篇 |
1996年 | 17篇 |
1995年 | 15篇 |
1994年 | 18篇 |
1993年 | 13篇 |
1992年 | 16篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 15篇 |
1986年 | 5篇 |
1985年 | 18篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1973年 | 17篇 |
1967年 | 4篇 |
排序方式: 共有1046条查询结果,搜索用时 15 毫秒
81.
A survey of metabolic changes in potato leaves by NMR‐based metabolic profiling in relation to resistance to late blight disease under field conditions
下载免费PDF全文
![点击此处可从《Magnetic resonance in chemistry : MRC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Satoru Tomita Seishi Ikeda Shogo Tsuda Nobutaka Someya Kenji Asano Jun Kikuchi Eisuke Chikayama Hiroshi Ono Yasuyo Sekiyama 《Magnetic resonance in chemistry : MRC》2017,55(2):120-127
Non‐targeted nuclear magnetic resonance (NMR)‐based metabolic profiling was applied to potato leaves to survey metabolic changes associated with late blight resistance under field conditions. Potato plants were grown in an experimental field, and the compound leaves with no visible symptoms were collected from 20 cultivars/lines at two sampling time points: (i) the time of initial presentation of symptoms in susceptible cultivars and (ii) 12 days before this initiation. 1H NMR spectra of the foliar metabolites soluble in deuterium oxide‐ or methanol‐d4‐based buffers were measured and used for multivariate analysis. Principal component analysis for six cultivars at symptom initiation showed a class separation corresponding to their levels of late blight resistance. This separation was primarily explained by higher levels of malic acid, methanol, and rutin and a lower level of sucrose in the resistant cultivars than in the susceptible ones. Partial least squares regression revealed that the levels of these metabolites were strongly associated with the disease severity measured in this study under field conditions. These associations were observed only for the leaves harvested at the symptom initiation stage, but not for those collected 12 days beforehand. Subsequently, a simple, alternative enzymatic assay for l ‐malic acid was used to estimate late blight resistance, as a model for applying the potential metabolic marker obtained. This study demonstrated the potential of metabolomics for field‐grown plants in combination with targeted methods for quantifying marker levels, moving towards marker‐assisted screening of new cultivars with durable late blight resistance. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
82.
Tawara H Doke T Hayashi T Kikuchi J Kyan A Nagaoka S Nakano T Takahashi S Terasawa K Yoshihira E 《Radiation measurements》2002,35(2):119-126
The LET distributions during the Space Shuttle missions STS-84 (altitude 270-412 km, average 375 km; inclination angle, 51.6 degrees) and STS-91 (altitude 328-397 km, average 373 km; inclination angle, 51.6 degrees) were measured using CR-39 plastic nuclear track detectors. A correction for the dip-angle dependence of the track-formation sensitivity of the CR-39 plates was applied to the data analysis. The absorbed doses and the dose equivalents around RRMD Detector Units, estimated from the LET distributions in the LET region of 4-200 keV/micrometers, fluctuated with standard deviations of +/- 21% to +/- 35% in both flight experiments. The LET distributions obtained from the CR-39 plates agreed well with that obtained from RRMD-II in STS-91. However, the particle fluxes obtained from RRMD-III in STS-84 and STS-91 were two or three times higher than those obtained from RRMD-II and the CR-39 plates. It was concluded that the LET distributions obtained from RRMD-II and the CR-39 plates in the present flight experiments did not include the contribution of target-fragmented secondary heavy particles produced by low-LET particles, such as relativistic or semi-relativistic protons and helium ions, whereas RRMD-III was able to detect these secondary particles because of its low triggering level. 相似文献
83.
We investigate numerically the dynamical behaviour of a polymer chain collapsing in a dilute solution. The rate of collapse is measured with and without the presence of hydrodynamic interactions. We find that hydrodynamic interactions both accelerate polymer collapse and alter the folding pathway. 相似文献
84.
85.
T. Fukuyama A. Ilakovac T. Kikuchi 《The European Physical Journal C - Particles and Fields》2008,56(1):125-146
We consider the leptonic and semileptonic (SL) lepton-flavor violating (LFV) decays of the charged leptons in the minimal
supersymmetric standard model (MSSM) with right-handed neutrinos. The parameters of the MSSM model are determined in the framework
of the minimal supersymmetric SO(10) GUT model assuming the minimal supergravity model of supersymmetry breaking. The free
parameters of the model are constrained adopting the WMAP cold dark matter constraint and adjusting the neutrino oscillation
data. So constrained, the SO(10) GUT model gives a definite prediction for the Dirac-neutrino Yukawa matrix, which induces
all LFV effects in the MSSM model through renormalization group equations of soft SUSY breaking parameters. A very detailed
numerical analysis has been made to define numerically all MSSM parameters necessary for the evaluation of the LFV amplitudes.
The basic LFV amplitudes in MSSM were rederived and improved. The formalism for the evaluation of all SL LFV amplitudes is
given. Numerical results for dominant SL LFV branching ratios, the anomalous magnetic moment of the muon and the ℓ→ℓ’γ branching
ratios are given. 相似文献
86.
Shin Kikuchi Naoki Kozuka Eiji Uchida Takafumi Ninomiya Haruyuki Tatsumi Hidekatsu Takeda Nobutada Tachi 《Physical Therapy Research》2008,11(1):23-27
Myotonic dystrophy (MyD) is a neuromuscular disease that is autosomal dominant and the most common form of muscular dystrophy affecting adults. The clinical features of MyD include a multisystemic disorder characterized by myotonia, progressive muscle weakness and wasting, cataracts, premature balding and mental retardation. The most severe type of MyD is classified as congenital MyD (CMyD). The muscle weakness in CMyD is very severe, but muscle development can be observed in the period of growth. However, no clinical case of this type has been reported yet. Therefore, we report on a girl with CMyD who had an increase in muscle strength over a four-year period. The girl with CMyD participated in this study from the age of 9 to the age of 12. The measurement of muscle strength was recorded as the maximum score of grip strength with the use of dynamometers. Grip strength was assessed once a year by the same two physical therapists. Grip strength of CMyD for each year was markedly weak when compared with the normal controls, but muscle strength changed within some specific growth areas. The muscle weakness in CMyD was remarkable, but the result showed that specific muscle strength of CMyD in childhood was actually increased. 相似文献
87.
Eriko Ohshima Keiji KusabaSinji Onodera Masae Kikuchi 《Journal of Physics and Chemistry of Solids》2002,63(3):419-423
High-pressure phase transition of Ta2NiO6 with the trirutile-type structure was investigated from the viewpoint of crystal chemistry. A new quenchable high-pressure phase was found in the pressure range higher than 7 GPa and 900°C. The high-pressure phase has an orthorhombic cell (a=4.797(1) Å, b=5.153(2) Å and c=14.85(1) Å and space group; Abm2), and it is more dense by 9.6% than the trirutile-structured phase. Infrared spectra of the trirutile-type phase and the high-pressure phase show that Ni2+ ions in the high-pressure phase are still in octahedral sites. The crystal structure of the high-pressure phase is considered as a cation-ordering trifluorite-type structure, which can be stabilized by a crystal field effect of Ni2+ ions. 相似文献
88.
Ohne Zusammenfassung 相似文献
89.
Photo-induced edge-shift affect in As2S3 film has been studies for different intensities of incident light. This process depends only on the total energy E of light. A simple experimental relationship between shift of edge Δλ and E has been obtained, which coincides with a theretical prediction deduced from a model based on a first-order reaction. 相似文献
90.
Novel spirocyclic trichothecanes, spirotenuipesine A and B, isolated from entomopathogenic fungus, Paecilomyces tenuipes 总被引:8,自引:0,他引:8
Kikuchi H Miyagawa Y Sahashi Y Inatomi S Haganuma A Nakahata N Oshima Y 《The Journal of organic chemistry》2004,69(2):352-356
Entomopathogenic fungi forming fruiting bodies have been employed as tonics and antitussives from ancient times. Paecilomyces tenuipes, which is also called Isaria japonica, is a very popular entomopathogenic fungus and is often considered a health food in northeast Asian countries such as China, Korea, and Japan. We cultivated the fruiting bodies of Paecilomyces tenuipes. Among the large-scale cultivations, fruiting body grown in barley grain contained two novel spirocyclic trichothecane derivatives, spirotenuipesine A (1) and B (2), and known trichothecane mycotoxins. Compounds 1 and 2 showed potent activity in neurotrophic factor biosynthesis in glial cells. The isolation of these compounds indicated that P. tenuipes is a promising source for producing various biologically active substances including trichothecanes. It is noteworthy that trichothecane mycotoxins are present in Paecilomyces tenuipes, which is typically used in medicinal health food. 相似文献