全文获取类型
收费全文 | 11513篇 |
免费 | 414篇 |
国内免费 | 47篇 |
专业分类
化学 | 7569篇 |
晶体学 | 79篇 |
力学 | 297篇 |
数学 | 2030篇 |
物理学 | 1999篇 |
出版年
2023年 | 70篇 |
2022年 | 141篇 |
2021年 | 179篇 |
2020年 | 233篇 |
2019年 | 239篇 |
2018年 | 262篇 |
2017年 | 247篇 |
2016年 | 405篇 |
2015年 | 379篇 |
2014年 | 398篇 |
2013年 | 754篇 |
2012年 | 837篇 |
2011年 | 853篇 |
2010年 | 533篇 |
2009年 | 483篇 |
2008年 | 673篇 |
2007年 | 635篇 |
2006年 | 611篇 |
2005年 | 559篇 |
2004年 | 448篇 |
2003年 | 394篇 |
2002年 | 342篇 |
2001年 | 189篇 |
2000年 | 158篇 |
1999年 | 119篇 |
1998年 | 99篇 |
1997年 | 88篇 |
1996年 | 115篇 |
1995年 | 66篇 |
1994年 | 91篇 |
1993年 | 57篇 |
1992年 | 72篇 |
1991年 | 75篇 |
1990年 | 75篇 |
1989年 | 67篇 |
1988年 | 54篇 |
1987年 | 47篇 |
1986年 | 38篇 |
1985年 | 63篇 |
1984年 | 80篇 |
1983年 | 42篇 |
1982年 | 56篇 |
1981年 | 49篇 |
1980年 | 54篇 |
1979年 | 40篇 |
1978年 | 40篇 |
1977年 | 51篇 |
1976年 | 40篇 |
1975年 | 40篇 |
1973年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Ra. Siegmund-Schultze 《Communications in Mathematical Physics》1985,100(2):245-265
It is shown that for a set of full measure with respect to any translation invariant probability distribution on the space of initial configurarations of classical particle systems on d with interaction given by a smooth superstable potential of finite range there is a solution to the Newtonian equations of motion, provided that the specific energy and the particle density of the initial configuration exist a.s. 相似文献
32.
P. Kratochvíl B. Smola I. Stulíková P. Vostrý F. Jandoš J. Šedivec 《Czechoslovak Journal of Physics》1985,35(3):257-260
Static softening of AISI 321 steel after cold and hot deformation characterizing the industrial thermomechanical treatment was studied by means of tensile tests and TEM. The deformation temperature, the strain and the grain size were the main parameters determining the final softening. The results can be applied for optimization of the solution annealing. 相似文献
33.
34.
Hitchcock PB Lappert MF Liu DS Sablong R 《Chemical communications (Cambridge, England)》2002,(17):1920-1921
The compounds [K((mu-N(SiMe3)C(Ph))2CH)(thf)2]infinity 1, [K(mu-N(SiMe3)C(Ph)C(H)C(Ph)NH)L]2 [L = (thf)2 2, tmen 3], [K(mu-NSi(Me)2C(Ph)C(H)C(Ph)N)(thf)3]2 4 and [K(N(H)C(Ph))2CH](thf)0.5 5 have been prepared from K[(N(SiMe3)C(Ph))2CH] and the X-ray structures of 1-4 are reported. 相似文献
35.
I. Labádi E. Pál R. Tudose O. Costisor 《Journal of Thermal Analysis and Calorimetry》2006,83(3):681-686
The
thermal behaviour of the mixed-ligand complexes of cobalt(II) and copper(I)
ions with antipyrine derivatives of 1,2-ethanediamine or piperazine (BAMP
and TAMEN), with water and with 2-mercapto-benzothiazole (Hmbt) was investigated.
The complexes contain 2-mercaptobenzothiazole (Hmbt, in the case of cobalt(II)
ion) or dimercaptobenzothiazine (mbt–mbt, in the case of copper(I) ion)
molecules as ligands and perchlorate (ClO4–) or
thiocyanate (SCN – ) ion as counterion. By heating, water and ligands
release the solid phase at lower temperature. At higher temperatures process
of different organic reactions of ligands (e.g. polymerization, polycondensation)
could be suggested to interpret the relative high final mass values. 相似文献
36.
Guillermo J. Aguilar María E. Gelpi Raúl A. Cadenas 《Journal of heterocyclic chemistry》1992,29(2):401-405
Several carbocyclic nucleoside analogs possessing a 6-substituted purine linked to a mesylated muco-inositol were synthesized. The coupling of triethylamine-activated 6-chloropurine with 2,3-anhydro-l,5,6-tri-O-(methanesulfonyl)-epi-inositol gave a 6-chloro purinyl muco-inositol amenable to further synthetic transformations in the heterocyclic moiety by substitution of the chlorine atom by nitrogen nucleophiles such as methylamino, diethylamino, benzylamino, hydrazino, morpholino, hydroxylamino, piperidino, and glycyl groups. 相似文献
37.
The aim of this work was the preparation of enantiomerically pure bis(pinene-bipyridine) ligands containing the ferrocenyl moiety. Several such ligands (1-3) were synthesized and completely characterized. These molecules can be diastereoselectively deprotonated at the acidic methylene group of the pinene moiety using a strong and sterically hindered base such as LDA. Subsequent reaction of the formed anion with alkyl halides yield the family of C(2)-symmetric enantiopure compounds (1a-c). Copper(I), silver(I), or zinc(II) complexes with several ligands (C1-C8) were prepared and structurally characterized in the solid state and in solution. Self-assembled helical species are formed in several cases. It became evident that the chiral groups present in the ligand do not completely determined the helical configuration of the assemblages. Diastereoselectivity is thus not complete with this type of ligands, contrary to other, similar ligands studied before. 相似文献
38.
Vibrational spectra of Ph4Si have been studied from 600 to 20 cm?1 in solution, in the melt and in the crystalline state. The assignments proposed for the substituent sensitive benzene ring vibrations, for the skeletal bending modes and ring librations have been supported by polarized IR and Raman measurements. The crystal spectra are interpreted on the basis of the S4 site symmetry of the molecules in the crystal. Two skeletal bending and four ring librational modes are supposed to appear below 120 cm?1, in the range of the lattice vibrations. 相似文献
39.
M. Pechál M. Strasák J. Vojtko M. Hrusovský 《Reaction Kinetics and Catalysis Letters》1982,20(1-2):157-161
The oxidation of aliphatic ketones by thallium(III) sulfate in aqueous medium has been studied from the point of view of the temperature effect and the enthalpy-entropy relationship. It has been found that the isokinetic relationship is fulfilled in this case.
(III) - . , .相似文献
40.
This paper presents a simple, rapid and reproducible method of analysis of salbutamol in pharmaceutical products, utilizing batch injection analysis (BIA) associated with amperometric detection. A study of salbutamol oxidation demonstrated a strong dependence between electrode fouling and pH. All determinations were done utilizing a glassy carbon electrode in presence of 3.0 mol l−1 NaOH. A large linear dynamic range from 8×10−7 to 2×10−4 mol l−1 was obtained by using an injected volume of 100 μl with a detection limit of 2.5×10−7 mol l−1. R.S.D. of 0.92% for 50 successive injections of 4×10−6 mol l−1 of salbutamol and a sample throughput of 60 samples per hour were achieved. The method was applied for salbutamol quantification in syrups. 相似文献