全文获取类型
收费全文 | 989篇 |
免费 | 29篇 |
国内免费 | 7篇 |
专业分类
化学 | 489篇 |
晶体学 | 17篇 |
力学 | 30篇 |
数学 | 139篇 |
物理学 | 350篇 |
出版年
2020年 | 8篇 |
2019年 | 15篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 16篇 |
2014年 | 24篇 |
2013年 | 60篇 |
2012年 | 32篇 |
2011年 | 47篇 |
2010年 | 15篇 |
2009年 | 22篇 |
2008年 | 39篇 |
2007年 | 41篇 |
2006年 | 43篇 |
2005年 | 48篇 |
2004年 | 29篇 |
2003年 | 30篇 |
2002年 | 29篇 |
2001年 | 25篇 |
2000年 | 18篇 |
1999年 | 10篇 |
1998年 | 10篇 |
1997年 | 12篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1994年 | 11篇 |
1993年 | 17篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 15篇 |
1989年 | 24篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1985年 | 28篇 |
1984年 | 18篇 |
1983年 | 8篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 19篇 |
1979年 | 7篇 |
1978年 | 18篇 |
1977年 | 15篇 |
1976年 | 14篇 |
1975年 | 12篇 |
1974年 | 10篇 |
1973年 | 7篇 |
1972年 | 8篇 |
1971年 | 8篇 |
1969年 | 8篇 |
排序方式: 共有1025条查询结果,搜索用时 15 毫秒
151.
Rochau GA Bailey JE Maron Y Chandler GA Dunham GS Fisher DV Fisher VI Lemke RW Macfarlane JJ Peterson KJ Schroen DG Slutz SA Stambulchik E 《Physical review letters》2008,100(12):125004
The Z-pinch dynamic hohlraum is an x-ray source for high energy-density physics studies that is heated by a radiating shock to radiation temperatures >200 eV. The time-dependent 300-400 eV electron temperature and 15-35 mg/cc density of this shock have been measured for the first time using space-resolved Si tracer spectroscopy. The shock x-ray emission is inferred from these measurements to exceed 50 TW, delivering >180 kJ to the hohlraum. 相似文献
152.
Trigo M Sheu YM Arms DA Chen J Ghimire S Goldman RS Landahl E Merlin R Peterson E Reason M Reis DA 《Physical review letters》2008,101(2):025505
Ultrafast laser excitation of an InGaAs/InAlAs superlattice (SL) creates coherent folded acoustic phonons that subsequently leak into the bulk (InP) substrate. Upon transmission, the phonons become "unfolded" into bulk modes and acquire a wave vector much larger than that of the light. We show that time-resolved x-ray diffraction is sensitive to this large-wave vector excitation in the substrate. Comparison with dynamical diffraction simulations of propagating strain supports our interpretation. 相似文献
153.
Rosner JL Alexander JP Cassel DG Duboscq JE Ehrlich R Fields L Gibbons L Gray R Gray SW Hartill DL Heltsley BK Hertz D Jones CD Kandaswamy J Kreinick DL Kuznetsov VE Mahlke-Krüger H Mohapatra D Onyisi PU Patterson JR Peterson D Riley D Ryd A Sadoff AJ Shi X Stroiney S Sun WM Wilksen T Athar SB Patel R Yelton J Rubin P Eisenstein BI Karliner I Mehrabyan S Lowrey N Selen M White EJ Wiss J Mitchell RE Shepherd MR Besson D Pedlar TK Cronin-Hennessy D Gao KY Hietala J Kubota Y Klein T Lang BW 《Physical review letters》2008,100(22):221801
We exploit the quantum coherence between pair-produced D0 and D[over]0 in psi(3770) decays to study charm mixing, which is characterized by the parameters x and y, and to make a first determination of the relative strong phase delta between D0-->K+pi- and D[over]0-->K+pi-. Using 281 pb(-1) of e+e- collision data collected with the CLEO-c detector at Ecm=3.77 GeV, as well as branching fraction input and time-integrated measurements of RM identical with (x2 + y2)/2 and RWS identical with Gamma(D0-->K+pi-)/Gamma(D[over]0-->K+pi-) from other experiments, we find cosdelta=1.03(-0.17)(+0.31)+/-0.06, where the uncertainties are statistical and systematic, respectively. By further including other mixing parameter measurements, we obtain an alternate measurement of cosdelta=1.10+/-0.35+/-0.07, as well as x sindelta=(4.4(-1.8)(+2.7)+/-2.9)x10(-3) and delta=(22(-12-11)(+11+9)) degrees . 相似文献
154.
Anna Peterson Mari-Liis Ludvig Jevgenija Martõnova Sandra Kaabel Paul Kerner Merle Uudsemaa 《Supramolecular chemistry》2020,32(5):313-319
ABSTRACT We demonstrate that Ullman fragment-coupling can be used to synthesise an oxacalix[4]arene monocarboxylic acid, which provides easy access to its water-soluble carboxylato derivatives. Crystallographic and computational data suggest that the new carboxyl-substituted oxacalix[4]arene adopts a 1,3-alternate conformation both in the solid-state and in methanol solution. Its water-soluble tetrabutylammonium derivate can detect the herbicide paraquat at neutral pH in aqueous media (K a = 111 ± 3 M–1) and in methanol (K a = 2020 ± 70 M–1). 相似文献
155.
Povarov I. G. Shilenkov N. A. Peterson I. V. Suboch G. A. Tovbis M. S. 《Russian Journal of Organic Chemistry》2019,55(5):730-733
Russian Journal of Organic Chemistry - Dimethyl 5-amino-2-hydroxy-4,6-dimethylisophthalate and dimethyl 5-amino-2-hydroxy-4,6-dimethylisophthalate were obtained in the free form for the first time.... 相似文献
156.
Roberto C. Arbulu Dr. Ying‐Bing Jiang Dr. Eric J. Peterson Prof. Dr. Yang Qin 《Angewandte Chemie (International ed. in English)》2018,57(20):5813-5817
New mechanisms for the controlled growth of one‐dimensional (1D) metal–organic framework (MOF) nano‐ and superstructures under size‐confinement and surface‐directing effects have been discovered. Through applying interfacial synthesis templated by track‐etched polycarbonate (PCTE) membranes, congruent polycrystalline zeolitic imidazolate framework‐8 (ZIF‐8) solid nanorods and hollow nanotubes were found to form within 100 nm membrane pores, while single crystalline ZIF‐8 nanowires grew inside 30 nm pores, all of which possess large aspect ratios up to 60 and show preferential crystal orientation with the {100} planes aligned parallel to the long axis of the pore. Our findings provide a generalizable method for controlling size, morphology, and lattice orientation of MOF nanomaterials. 相似文献
157.
John R. Peterson Jordan K. Zjawiony Alice M. Clark Charles D. Hufford Robin D. Rogers 《Journal of chemical crystallography》1995,25(5):223-226
3-Methylsampangine, C16H10N2O, crystallizes in the monoclinic space group P21/c witha=7.260(3),b=10.697(5),c=15.342(6) Å, and =102.69(4). All nonhydrogen atoms of this potent antifungal agent are planar to within 0.082 Å. The title compound exhibits potentin vitro antifungal activity againstC. neoformans, C. albicans andA. fumigatus. 相似文献
158.
We consider amalgamated free product II1 factors M = M
1*B
M
2*B
… and use “deformation/rigidity” and “intertwining” techniques to prove that any relatively rigid von Neumann subalgebra Q ⊂ M can be unitarily conjugated into one of the M
i
’s. We apply this to the case where the M
i
’s are w-rigid II1 factors, with B equal to either C, to a Cartan subalgebra A in M
i
, or to a regular hyperfinite II1 subfactor R in M
i
, to obtain the following type of unique decomposition results, àla Bass–Serre: If M = (N
1 * CN2*C
…)
t
, for some t > 0 and some other similar inclusions of algebras C ⊂ N
i
then, after a permutation of indices, (B ⊂ M
i
) is inner conjugate to (C ⊂ N
i
)
t
, for all i. Taking B = C and , with {t
i
}
i⩾1 = S a given countable subgroup of R
+
*, we obtain continuously many non-stably isomorphic factors M with fundamental group equal to S. For B = A, we obtain a new class of factors M with unique Cartan subalgebra decomposition, with a large subclass satisfying and Out(M) abelian and calculable. Taking B = R, we get examples of factors with , Out(M) = K, for any given separable compact abelian group K. 相似文献
159.
An isoform-selective, small-molecule inhibitor targets the autoregulatory mechanism of p21-activated kinase 总被引:1,自引:0,他引:1
Deacon SW Beeser A Fukui JA Rennefahrt UE Myers C Chernoff J Peterson JR 《Chemistry & biology》2008,15(4):322-331
Autoregulatory domains found within kinases may provide more unique targets for chemical inhibitors than the conserved ATP-binding pocket targeted by most inhibitors. The kinase Pak1 contains an autoinhibitory domain that suppresses the catalytic activity of its kinase domain. Pak1 activators relieve this autoinhibition and initiate conformational rearrangements and autophosphorylation events leading to kinase activation. We developed a screen for allosteric inhibitors targeting Pak1 activation and identified the inhibitor IPA-3. Remarkably, preactivated Pak1 is resistant to IPA-3. IPA-3 also inhibits activation of related Pak isoforms regulated by autoinhibition, but not more distantly related Paks, nor >200 other kinases tested. Pak1 inhibition by IPA-3 in live cells supports a critical role for Pak in PDGF-stimulated Erk activation. These studies illustrate an alternative strategy for kinase inhibition and introduce a highly selective, cell-permeable chemical inhibitor of Pak. 相似文献
160.