全文获取类型
收费全文 | 179篇 |
免费 | 0篇 |
专业分类
化学 | 119篇 |
力学 | 1篇 |
数学 | 13篇 |
物理学 | 18篇 |
无线电 | 28篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2011年 | 6篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 5篇 |
2007年 | 15篇 |
2006年 | 8篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1975年 | 10篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
排序方式: 共有179条查询结果,搜索用时 15 毫秒
1.
Chuang C.T. Chin K. Stork J.M.C. Patton G.L. Crabbe E.F. Comfort J.H. 《Solid-State Circuits, IEEE Journal of》1992,27(2):225-228
A detailed study on the leverage of high-f T transistors for advanced high-speed bipolar circuit applications is presented. It is shown that for the standard ECL (emitter-coupled logic) circuit, the leverage of high f T is limited by the passive resistors (emitter-follower resistor and collector load resistor) and wire delay, especially in the low-power regime. For the standard NTL (nonthreshold logic) circuit, the leverage is higher due to its front-end configuration and lower power supply value. As the passive resistors are decoupled from the delay path in various advanced circuits utilizing active-pull-down schemes, the leverage of high FT becomes more significant 相似文献
2.
Can computer systems help us understand paintings and the methods of great masters? In this three-part series, David C. Stork describes how he uses techniques adapted from computer vision and image analysis to shed light on art and problems in art history. In part 1, the subject is perspective, and among the questions posed: did the artists of the Renaissance use optical projections as has been recently hypothesized?. 相似文献
3.
organocuprate reactions of enone lactones. I. Synthesis of trans-fused rings via conjugate addition.
Control of the stereochemistry of substituents needed to construct a bicyclic system (e.g. a hydrindanone) is achieved by conjugate addition of an organocuprate to a cyclohexenone made conformationally rigid by the attachment of a 1,3-lactone. 相似文献
4.
J. G. Schindler G. Stork und H. -J. Strüh 《Fresenius' Journal of Analytical Chemistry》1978,292(5):396-399
Zusammenfassung Es wird über die Optimierung einer Kalium-Valinomycin-Diskelektrode durch den kombinierten Zusatz verschiedener Weichmacher berichtet. Die Inkorporation dreier Weichmacher (Diphenyläther, Dinonylphthalat, Trisäthylhexylphosphat) in die PVC-Membran führt zu einer Elektrode, die wesentliche Funktionskriterien für eine Anwendung in der klinischen Analytik erfüllt.
Optimization of a potassium-valinomycin disc electrode
Summary Optimization of a potassium valinomycin disc electrode by adding a combination of several plasticisers is reported. Incorporation of three plasticisers (diphenyl ether, dinonyl phthalate, trisethylhexyl phosphate) into the PVC membrane results in an electrode, which has all qualities for application in clinical analysis.
Wir danken dem Fonds der Chemischen Industrie und der Firma Fresenius Apparatebau KG, Bad Homburg v.d.H., für die Unterstützung dieser Arbeit. 相似文献
5.
On reaction of 1,2:5,6-di-O-isopropylidenc-3-O-(p-tolylsulfonyl)-α-D-glueofuranose ( 1 ) with hydrazine hydrate at 140° besides formation of 3-deoxy-3-hydrazino-1,2:5,6-di-O-isopropylidene-α-D-allofuranose ( 2 ) and 3-dcoxy-1,2:5,6-di-O-isopropylidene-α-D-erythro-hex-3-enofuranose ( 3 ), ring transformation into 3-[4′-(2′,2′-dimethyl-1′,3′-dioxolanyl)]pyridazine ( 4 ) takes place. At 170°, however, only 2 and 4 are formed, indicating that 3 is the precursor of 4. Treatment of 3 with hydrazine hydrate at 170° indeed gives a nearly quantitative ring expansion into 4. Treatment of 3-dcoxy-3-hydrazino-1,2:5,6-di-O-isopropylidenc-α-D-glucofuranose ( 8 ) as well as the stereoisomeric allofuranose 2 with concentrated hydrochloric acid gives a nearly quantitative ring interconversion into 3-(D-erythro-trihydroxypropyl)pyrazole ( 9 ). 相似文献
6.
Na2B2Se7, K2B2S7, and K2B2Se7: Three Perchalcogenoborates with a Novel Polymeric Anion Network Na2B2Se7 (I 2/a; a = 11.863(4) Å, b = 6.703(2) Å, c = 13.811(6) Å, β = 109.41(2)°; Z = 4), K2B2S7 (I 2/a; a = 11.660(2) Å, β = 6.827(1) Å, c = 12.992(3) Å, β = 106.78(3)°; Z = 4), and K2B2Se7 (I 2/a; a = 12.092(4) Å, b = 7.054(2) Å, c = 13.991(5) Å, β = 107.79(3)°; Z = 4) were prepared by reaction of stoichiometric amounts of sodium selenide (potassium sulfide) with boron and sulfur or of potassium selenide and boron diselenide, respectively, at 600°C with subsequent annealing. The crystal structures consist of polymeric anion chains of composition ([B2S7]2?)n or ([B2Se7]2?)n formed by spirocyclically connected five-membered B2S3 (B2Se3) rings and six-membered B2S4 (B2Se4) rings. The nine-coordinate alkaline metal cations are situated in between. 相似文献
7.
Asymptotics of the Interband Light Absorption Coefficient near the Band Edge for an Alloy-Type Model
We find the asymptotics of the interband light absorption coefficient of an alloy-type model in the case when the ground-state energies of the electron and the hole Hamiltonians are finite. 相似文献
8.
Heterojunction bipolar transistors using Si-Ge alloys 总被引:1,自引:0,他引:1
Iyer S.S. Patton G.L. Stork J.M.C. Meyerson B.S. Harame D.L. 《Electron Devices, IEEE Transactions on》1989,36(10):2043-2064
Advanced epitaxial growth techniques permit the use of pseudomorphic Si1-xGex alloys in silicon technology. The smaller bandgap of these alloys allows for a variety of novel band-engineered structures that promise to enhance silicon-based technology significantly. The authors discuss the growth and properties of pseudomorphic Si1-xGex structures and then focus on their applications, especially the Si1-xGex -base heterojunction bipolar transistor (HBT). They show that HBTs in the Si1-xGex system allow for the decoupling of current gain and intrinsic base resistance. Such devices can be made by using a variety of techniques, including molecular-beam epitaxy and chemical vapor deposition. The authors describe the evolution of fabrication schemes for such HBTs and describe the DC and AC results obtained. They show that optimally designed HBTs coupled with advanced bipolar structures can provide performance leverage 相似文献
9.
Ludwig Stork Xiaohui Liu Boniface P. T. Fokwa Richard Dronskowski 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(8):i54-i56
Green single crystals of trans‐tetraamminedibromidochromium(III) trans‐diamminetetrabromidochromate(III), [CrBr2(NH3)4][CrBr4(NH3)2], are found to contain two symmetry‐independent sixfold coordinated CrIII cations on centres of inversion. The structure is composed of octahedral trans‐[CrBr2(NH3)4]+ cations and octahedral trans‐[CrBr4(NH3)2]− anions, and adopts a distorted CsCl‐type lattice. The cations and anions are linked by N—H...Br interactions. This is the first example in which both ions are mixed ammine–bromide CrIII complexes. 相似文献
10.
W. Spickermann und G. Stork 《Fresenius' Journal of Analytical Chemistry》1986,323(1):38-43
Zusammenfassung Die aus Untersuchungen an 40 Sedimentproben der Lahn gewonnenen Analysenergebnisse (insgesamt 18 Variablen) wurden mit Hilfe von Verfahren der multivariaten Statistik ausgewertet. Zum Einsatz kamen die multiple Korrelationsrechnung, die Faktorenanalyse, die Clusteranalyse und die multiple Regressionsanalyse. Diese chemometrische Auswertung lieferte unter anderem Hypothesen über die relative Bedeutung verschiedener Bindungsarten (Bindung durch Kationenaustausch und Adsorption, organische, hydroxidische und carbonatische Bindung) der vier toxischen Schwermetalle Kupfer, Quecksilber, Cadmium und Blei in den Lahnsedimenten.
Studies on sediments of the river Lahn2. Chemometric evaluation
Summary The analytical results of investigations on 40 samples of sediments of the river Lahn were evaluated by multivariate statistical methods. We accomplished multiple correlation analysis, factor analysis, cluster analysis and multiple regression analysis. Using this chemometric approach we obtained information about the relative importance of the different types of bonding (bonding by organic substances, hydroxides and carbonates and by cation-exchange and adsorption) for the toxic heavy metals copper, mercury, cadmium and lead in the sediments of the river Lahn.相似文献