全文获取类型
收费全文 | 7810篇 |
免费 | 172篇 |
国内免费 | 2篇 |
专业分类
化学 | 4493篇 |
晶体学 | 167篇 |
力学 | 157篇 |
数学 | 1157篇 |
物理学 | 2010篇 |
出版年
2022年 | 200篇 |
2021年 | 181篇 |
2020年 | 118篇 |
2019年 | 146篇 |
2018年 | 149篇 |
2017年 | 143篇 |
2016年 | 241篇 |
2015年 | 199篇 |
2014年 | 277篇 |
2013年 | 631篇 |
2012年 | 382篇 |
2011年 | 432篇 |
2010年 | 337篇 |
2009年 | 310篇 |
2008年 | 346篇 |
2007年 | 343篇 |
2006年 | 294篇 |
2005年 | 240篇 |
2004年 | 229篇 |
2003年 | 228篇 |
2002年 | 169篇 |
2001年 | 142篇 |
2000年 | 137篇 |
1999年 | 94篇 |
1998年 | 102篇 |
1997年 | 73篇 |
1996年 | 76篇 |
1995年 | 100篇 |
1994年 | 58篇 |
1993年 | 43篇 |
1992年 | 73篇 |
1991年 | 47篇 |
1990年 | 70篇 |
1989年 | 58篇 |
1988年 | 76篇 |
1987年 | 60篇 |
1986年 | 65篇 |
1985年 | 100篇 |
1984年 | 108篇 |
1983年 | 67篇 |
1982年 | 65篇 |
1981年 | 68篇 |
1980年 | 83篇 |
1979年 | 57篇 |
1978年 | 65篇 |
1977年 | 68篇 |
1976年 | 66篇 |
1975年 | 53篇 |
1974年 | 47篇 |
1973年 | 44篇 |
排序方式: 共有7984条查询结果,搜索用时 15 毫秒
31.
Hubert Grudzński 《Reports on Mathematical Physics》2004,53(3):331-338
New elements of the dual cone of the set of fermion N-representable 2-density operators are proposed. So far, the explicit form of the corresponding necessary conditions for N-representability is obtained for N = 3. In this case the new condition is stronger than the known B- and C-conditions for 3-representability. The results provide evidence that in the spectral decomposition of the N-representable 2-density operator there exists an intrinsic relation between the eigenvalue and the corresponding eigenfunction. 相似文献
32.
Orewczyk J. Jasieńska S. Iwanczenko S. 《Journal of Thermal Analysis and Calorimetry》1998,54(1):79-84
This paper presents applications of thermal analysis to observe the course of reduction of acidic pellets, metallurgical substances
whose reducibility and strength are basic parameters of use in blast furnace processes. Both parameters depend on the mineral
composition of the samples. The investigations included determination of the chemical and phase compositions of the initial
samples and reduction products.
Research was conducted on acidic pellets from Połtawa (Poland), applied in the T. Sendzimir Steelworks (Poland), in comparison
with pellets from Brazil, Canada and Lebedyn (Russia).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
33.
34.
Zbigniew Peradzyński Bogdan Kazmierczak 《Archive of Applied Mechanics (Ingenieur Archiv)》2005,74(11-12):827-833
The influence of mechano-chemical coupling on calcium concentration waves is considered. The propagation of calcium waves is described by a reaction–diffusion equation with the reaction term dependent on the mechanical stress responsible for the release of calcium. Similarly the balance of mechanical forces is influenced by the calcium concentration through the so-called traction force. 相似文献
35.
Dealing with infinite iterated function systems we introduce and develop the ergodic theory of Hölder systems of functions similarly as in [HU] and [HMU]. In the context of conformal infinite iterated function systems we prove the volume lemma for the Hausdorff dimension of the projection onto the limit set of a shift invariant measure. This can be considered as a Billingsley type result. Our cenral goal is to demonstrate the appearance of the "singularity-absolute continuity" dichotomy for equilibrium states of Hölder systems of functions which has been observed in [PUZ,I] and [PUZ,II] (see also [DU1] and [DU2]) in the setting of rational functions of the Riemann sphere. 相似文献
36.
37.
X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) have been used to investigate the effect of reactive ion etching (RIE) on poly(methylhydrogensiloxane-co-dimethylsiloxane) surface in fluorine-based plasmas. Polysiloxane layers supported on the standard silicon wafers were etched using SF6 + O2 or CF4 + O2 plasmas. SEM studies show that the polysiloxane morphology depends on plasma chemical composition strongly. Presence of a columnar layer likely covered with a fluorine rich compound was found on the elastomer surface after the CF4 + O2 plasma exposure. After the SF6 + O2 or CF4 + O2 plasma treatment the polysiloxane surface enriches with fluorine or with fluorine and aluminum, respectively. Different morphologies and surface chemical compositions of the silicone elastomer etched in both plasmas indicate different etching mechanisms. 相似文献
38.
We describe phenomena occurring just before a saddle-node bifurcation for one-parameter families of interval maps. In particular, as a parameter approaches the bifurcation value, attracting periodic orbits of periodsk, k+1,k+2,k+3,... can appear. We make a detailed study of a family of cusp-shaped maps, where this phenomenon occurs in a pure form. 相似文献
39.
Monoclinic (N2H6)3Zr2F13·F crystallizes in space group P21-C
2
2
(No. 4) with unit cell dimensionsa=5.670(1),b=10.984(2),c=10.601(2) Å,=93.88(1)°,V=658.7(4) Å3 andZ=2. Two different types of N2H6
2+ ions are present. One is involved in strong H-bonds to F– ions in infinite chains running along the a axis (the shortest N-F distance is 2.437(5) Å), and the other links the structure through weaker bi- and trifurcated H-bonds to fluorine ligands of the Zr2F13
5– ions. The N-N bond lengths range from 1.430(5) to 1.446(5) Å with apparently no meaningful correlation to the type of N2H2
2+ ions. The Zr2F13
5– ions have very nearly C2 point symmetry and are formed by joining two distorted bicapped trigonal prisms of ZrF8-units through a common face. Distances of Zr-F terminal bonds range from 2.015(2) to 2.112(2) Å and of bridging bonds from 2.133(2) to 2.212(2) Å. (N2H6)3Hf2F13·F is isomorphous. The vibrational spectra of the two compounds are nearly identical, with the exception of a strong infrared band, which is assigned to a stretching mode with the moving central atom within the anion. The anion part of the spectrum is simple, showing broad unresolved bands. The cation part shows two types of N2H6
– ions. H-Bonding is strongly present in the spectra, but no simple correlations with the H-bond strength is evident. 相似文献
40.
Dr. A. Kaczyński Dr. S. J. Matysiak 《Archive of Applied Mechanics (Ingenieur Archiv)》1988,58(2):137-147
Summary This paper deals with the two-dimensional static punch problems in the presence of friction for a periodically layered half-space. Within the framework of the homogenized model of linear elasticity with microlocal parameters [8–11] the exact solutions of the considered problems are obtained. The case of the indentation of the composite body by a rigid rectangular punch has been discussed in detail.
Ebene Kontaktprobleme für ein periodisches elastisches Zweischichten-Komposit
Übersicht In dieser Arbeit wird das zweidimensionale statische Stempelproblem mit Reibung für einen periodisch geschichteten Halbraum betrachtet. Im Rahmen eines Homogenisierungsmodells der linearen Elastizitätstheorie mit mikropolaren Parametern werden die exakten Lösungen der betrachteten Probleme gewonnen. Im Detail wird das Eindringen eines rechteckigen starren Stempels behandelt.相似文献