全文获取类型
收费全文 | 20716篇 |
免费 | 153篇 |
国内免费 | 9篇 |
专业分类
化学 | 19148篇 |
晶体学 | 13篇 |
力学 | 61篇 |
数学 | 969篇 |
物理学 | 687篇 |
出版年
2013年 | 200篇 |
2012年 | 172篇 |
2011年 | 193篇 |
2007年 | 181篇 |
2006年 | 192篇 |
2005年 | 179篇 |
2004年 | 175篇 |
1988年 | 172篇 |
1987年 | 221篇 |
1986年 | 220篇 |
1985年 | 302篇 |
1984年 | 278篇 |
1982年 | 203篇 |
1981年 | 165篇 |
1980年 | 409篇 |
1979年 | 287篇 |
1978年 | 1121篇 |
1977年 | 869篇 |
1976年 | 291篇 |
1975年 | 160篇 |
1974年 | 155篇 |
1973年 | 157篇 |
1972年 | 187篇 |
1970年 | 180篇 |
1968年 | 224篇 |
1967年 | 197篇 |
1966年 | 249篇 |
1965年 | 274篇 |
1964年 | 252篇 |
1963年 | 196篇 |
1962年 | 366篇 |
1961年 | 194篇 |
1960年 | 231篇 |
1959年 | 216篇 |
1958年 | 220篇 |
1957年 | 155篇 |
1956年 | 249篇 |
1955年 | 235篇 |
1954年 | 178篇 |
1943年 | 172篇 |
1939年 | 166篇 |
1938年 | 176篇 |
1937年 | 233篇 |
1936年 | 219篇 |
1935年 | 237篇 |
1934年 | 189篇 |
1933年 | 260篇 |
1930年 | 222篇 |
1928年 | 161篇 |
1927年 | 156篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Peter A. Markowich Gerhard Rein Gershon Wolansky 《Journal of statistical physics》2002,106(5-6):1221-1239
We consider the Schrödinger–Poisson system in the repulsive (plasma physics) Coulomb case. Given a stationary state from a certain class we prove its nonlinear stability, using an appropriately defined energy-Casimir functional as Lyapunov function. To obtain such states we start with a given Casimir functional and construct a new functional which is in some sense dual to the corresponding energy-Casimir functional. This dual functional has a unique maximizer which is a stationary state of the Schrödinger–Poisson system and lies in the stability class. The stationary states are parameterized by the equation of state, giving the occupation probabilities of the quantum states as a strictly decreasing function of their energy levels. 相似文献
112.
S. Ebel B. Reyer und A. Werner-Busse 《Fresenius' Journal of Analytical Chemistry》1987,327(2):193-197
Summary This paper describes a reliable working station for the in line-process control in chemical plants. Essential parts of the equipment (pump, column) are in duplicates and may be combined by computer control in different lines. One pump and column is in working position, the other is held in ready to work position by conditioning. While one column is in working position, the system is able to calibrate the other column and to switch to this column in the case of breakdown of the other column. By means of chromatographic data (as retention time, peak height of standards, data of separation) the working column is under control and the switching to the other column is down before a real breakdown. The status of the detector is followed by number and distance in time of the necessary auto-zero operations and by the noise of the lamp.
Herrn Prof. Dr. W. Fresenius aus Anlaß des 125jährigen Erscheinens der Fresenius Zeitschrift für Analytische Chemie gewidmet 相似文献
Herrn Prof. Dr. W. Fresenius aus Anlaß des 125jährigen Erscheinens der Fresenius Zeitschrift für Analytische Chemie gewidmet 相似文献
113.
114.
The present study aims at antimicrobial polyethylene surfaces. To achieve this, LLDPE was compounded with the polymeric biocide poly(2-tert-butylaminoethyl) methacrylate TBAM (bulk modification with 1.5-5.0 wt.% of TBAM). Surfaces of these polymer compounds were then subjected to microbial assays. Using standard methods the colony forming units (CFU) for Escherichia coli and Staphylococcus aureus were determined on these surfaces. In all cases, polyethylene surfaces with highly antimicrobial properties were achieved. An average reduction of 104 CFU ml−1 compared to neat LLDPE was achieved. The surfaces of these LLDPE/TBAM compounds were assessed by electrokinetic (zeta potential) measurements. The results indicate a relation between the antimicrobial activity and the zeta-potential of the polymer compounds. Moreover, the antimicrobial compounds were investigated towards biofilm formation. Compared to pristine LLDPE, the surfaces of the polymer compounds showed less adhering biofilm after a testing period of 16 weeks. 相似文献
115.
According to the theory of superselection sectors of Doplicher, Haag, and Roberts, field operators which make transitions between different superselection sectors—i.e. different irreducible representations of the observable algebra—are to be constructed by adjoining localized endomorphisms to the algebra of local observables. We find the relevant endomorphisms of the chiral algebra of observables in the minimal conformal model with central chargec=1/2 (Ising model). We show by explicit and elementary construction how they determine a representation of the braid groupB
which is associated with a Temperley-Lieb-Jones algebra. We recover fusion rules, and compute the quantum dimensions of the superselection sectors. We exhibit a field algebra which is quantum group covariant and acts in the Hilbert space of physical states. It obeys local braid relations in an appropriate weak sense. 相似文献
116.
H. Jork und H. Kurtenacker 《Fresenius' Journal of Analytical Chemistry》1964,204(5):355-356
Ohne Zusammenfassung 相似文献
117.
Gerhard Kramer 《Fresenius' Journal of Analytical Chemistry》1937,111(5-6):169-176
Zusammenfassung Entgegen den Auffassungen von van Zijp über den von ihm veröffentlichten Nachweis des Aluminiums mit Ammoniummolybdat wurde gezeigt, daß ein derartiger Nachweis Empfindlichkeit und Störungsfreiheit in hohem Grade vereint.Der Nachweis durch Ammoniummolybdat konnte auf Beryllium ausgedehnt werden. Eine Reihe von Versuchen zeigte, daß Aluminium- und Berylliummolybdat in zwei verschiedenen Krystallformen ohne gegenseitige Beeinträchtigung selbst nebeneinander auszukrystallisieren vermögen.Es ist mir eine angenehme Pflicht, Herrn Prof. Dr. Wilhelm Böttger für sein stets färderndes Interesse und für die mikrochemische Arbeitsmäglichkeit überhaupt zu danken. Zu Dank verpflichtet bin ich auch der Fa. Otto Perutz, München für die freundliche überlassung von Pervola-Platten zu den Mikrophotographien. 相似文献
118.
Dorris Heiligmann und L. Acker 《Fresenius' Journal of Analytical Chemistry》1955,144(4):291-294
Ohne Zusammenfassung 相似文献
119.
M. Weber N. Trautmann H. Menke G. Herrmann und N. Kaffrell 《Fresenius' Journal of Analytical Chemistry》1973,267(3):192
Ohne ZusammenfassungDie ausführliche Veröffentlichung erfolgt in Radiochimica Acta [3]. 相似文献
120.
Gerhard Full Peter Winterhalter Gertraut Schmidt Peter Herion Peter Schreier 《Journal of separation science》1993,16(11):642-644
This paper reports the differentiation between the enantiomers of theaspiranes and theaspirones, potent flavor compounds widely used in the flavor industry. Optically pure reference compounds of isomeric theaspiranes were obtained by enantioselective synthesis. Enantiomerically pure reference theaspirones were isolated from quince fruit; their absolute stereochemistry was assigned by CD spectroscopy. For both types of compounds the order of elution was elucidated by using authentic reference compounds. These data enabled the determination of the enantiomeric distribution of both types of compounds in a variety of plant tissues. Because of the complexity of the natural flavor isolates, compounds were identified by mass spectrometry after multidimensional gas chromatography employing a Sichromat 2 double oven chromatograph. After separation of the target compounds on the first, achiral, column (DB-5), they were transferred to a chiral column (C-Dex B) for determination of the enantiomeric distribution. Multiple ion detection (MID) enabled the determination of the enantiomeric distribution even for complex mixtures containing the target compounds at extremely low levels. 相似文献