全文获取类型
收费全文 | 301篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
化学 | 163篇 |
晶体学 | 4篇 |
力学 | 9篇 |
数学 | 33篇 |
物理学 | 98篇 |
出版年
2018年 | 3篇 |
2016年 | 2篇 |
2014年 | 6篇 |
2013年 | 14篇 |
2012年 | 11篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 16篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 7篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1942年 | 2篇 |
1941年 | 2篇 |
1935年 | 2篇 |
1930年 | 3篇 |
排序方式: 共有307条查询结果,搜索用时 15 毫秒
21.
Davies CJ Griffith JD Sederman AJ Gladden LF Johns ML 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,187(1):170-175
Analysis of diffusion measurements as a function of observation time (Delta), to calculate surface-to-volume ratios (S/V) and tortuosities (kappa), is a useful tool in the characterisation of porous media using NMR. However, using conventional pulsed field gradient (PFG) measurements, this requires long total experiment times (typically hours). Here, we show how the rapid diffusion measurement pulse sequence, Difftrain, can be used to provide the required experimental data much more rapidly (typically within minutes) with a consequential reduction in total experiment time of typically over an order of magnitude. Several novel modifications to the Difftrain pulse sequence are also presented to tailor it to this particular application; these include a variable delay between echoes (to ensure optimal echo position with respect to Delta) and a variable tip angle for the refocusing pulse (to ensure optimal use of available signal). Difftrain is applied to measure both S/V and kappa for a model glass bead pack; excellent agreement is found with both a conventional PFG measurement and with a bulk gravimetric measurement of S/V. 相似文献
22.
Dr. Andrew T. Krueger Dr. Carsten Kroll Edgar Sanchez Prof. Linda G. Griffith Prof. Barbara Imperiali 《Angewandte Chemie (International ed. in English)》2014,53(10):2662-2666
Described is the development and application of a versatile semisynthetic strategy, based on a combination of sortase‐mediated coupling and tetrazine ligation chemistry, which can be exploited for the efficient incorporation of tunable functionality into chimeric recombinant proteins. To demonstrate the scope of the method, the assembly of a set of bivalent ligands, which integrate members of the epidermal growth factor (EGF) ligand family, is described. By using a series of bivalent EGFs with variable intraligand spacing, the differences in structure were correlated with the ability to bias signaling in the ErbB receptor family in a cell motility assay. Biasing away from EGFR‐HER2 dimerization with a bivalent EGF was observed to reduce cell motility in an intraligand distance‐dependent fashion, thus demonstrating the utility of the approach for acutely perturbing receptor‐mediated cell signaling pathways. 相似文献
23.
The syntheses of p-terphenylphosphonic acid and p,p″-terphenyl-bis-phosphonic acid have been developed, and the resulting products were used to prepare layered Th(IV) and Zr(IV) phosphonates. The monoacidic terphenyl species formed a bilayered structure while the diacid created a pillared geometry. Mixed component phases were also produced. Synthesis, characterization, X-ray and thermal properties of these materials are discussed. 相似文献
24.
Griffith BR Allen BL Rapraeger AC Kiessling LL 《Journal of the American Chemical Society》2004,126(6):1608-1609
We report the design and synthesis of well-defined polymers for the noncovalent oligomerization of proteins. The reported scaffolds, which were generated by atom-transfer radical polymerization (ATRP), take advantage of the well-characterized interaction between a Ni2+ complex and an oligohistidine sequence (His tag). Thus, our polymers are designed to facilitate the oligomerization of any protein possessing a His tag. We demonstrate that they can oligomerize fibroblast growth factor-8b (FGF-8b) and promote FGF-8b-mediated cell proliferation in the absence of heparin. 相似文献
25.
We present the first results of a new search for a permanent electric dipole moment of the 199Hg atom using a UV laser. Our measurements give d(199Hg) = -(1.06+/-0.49+/-0.40)x10(-28)e cm. We interpret the result as an upper limit absolute value [d(199Hg)]<2.1x10(-28)e cm (95% C.L.), which sets new constraints on theta bar;(QCD), chromo-EDMs of the quarks, and CP violation in supersymmetric models. 相似文献
26.
Tkaczyk S Tollefson K Tollestrup A Toyoda H Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Valls J Vejcik S Velev G Vidal R Vilar R Vologouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D 《Physical review letters》2000,84(6):1110-1115
We search for color singlet technirho and technipion production in p&pmacr; collisions at sqrt[s] = 1.8 TeV recorded with the Collider Detector at Fermilab. These exotic technimesons are present in a model of walking technicolor. The signatures studied are lepton plus two jets plus E(T) and multijet final states. No excess of events is seen in either final state. We set an upper limit on the technirho production cross section and exclude a region in the technipion mass versus technirho mass plane. 相似文献
27.
Toyoda H Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Vaiciulis T Valls J Vejcik S Velev G Vidal R Vilar R Volobouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D Watts T Webb R 《Physical review letters》2000,84(22):5043-5048
We report results from a study of events with a leading antiproton of beam momentum fraction 0.9057 GeV. Using the dijet events, we evaluate the diffractive structure function of the antiproton and compare it with expectations based on results obtained in diffractive deep inelastic scattering experiments at the DESY ep collider HERA. 相似文献
28.
29.
M. P. Dancy J. Billowes I. S. Grant D. E. Evans J. A. R. Griffith S. A. Wells D. A. Eastham J. Groves J. R. H. Smith D. W. L. Tolfree P. M. Walker 《Hyperfine Interactions》1990,59(1-4):193-196
East particle-photon coincidence techniques, developed at Daresbury with strontium isotopes, allow ultrasensitive laser fluorescence
spectroscopy of beams of radio-active isotopes which can only be produced in very low yields. The technique has now been applied
to neutron-deficient barium isotopes down to120Ba. From measured hyperfine splittings and isotope shifts, nuclear moments and changes in mean square radii have been determined.
The work has revealed an abrupt increase in the mean square radius for121Ba large enough to disrupt the systematic staggering of nuclear size seen for the series. In a recent experiment an isomeric
state of127Ba with a half-life of about 2 seconds has been produced in a very low yield; nevertheless we have succeeded in obtaining
a fluorescence spectrum. 相似文献
30.
Using the approach of Rulla (1996 SIAM J. Numer. Anal. 33, 68-87)for analysing the time discretization error and assuming moreregularity on the initial data, we improve on the error boundderived by Barrett and Blowey (1996 IMA J. Numer. Anal. 16,257-287) for a fully practical piecewise linear finite elementapproximation with a backward Euler time discretization of amodel for phase separation of a multi-component alloy. 相似文献