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排序方式: 共有1195条查询结果,搜索用时 31 毫秒
1.
2.
Henri de Maissin Philipp R. Groß Obaid Mohiuddin Dr. Moritz Weigt Luca Nagel Marvin Herzog Zirun Wang Robert Willing Dr. Wilfried Reichardt Dr. Martin Pichotka Dr. Lisa Heß Prof. Dr. Thomas Reinheckel Prof. Dr. Henning J. Jessen Prof. Dr. Robert Zeiser Prof. Dr. Michael Bock Prof. Dominik von Elverfeldt Prof. Dr. Maxim Zaitsev Dr. Sergey Korchak Dr. Stefan Glöggler Prof. Dr. Jan-Bernd Hövener Prof. Dr. Eduard Y. Chekmenev Prof. Dr. Franz Schilling Dr. Stephan Knecht Dr. Andreas B. Schmidt 《Angewandte Chemie (International ed. in English)》2023,62(36):e202306654
3.
A Ruthenium(II)–Copper(II) Dyad for the Photocatalytic Oxygenation of Organic Substrates Mediated by Dioxygen Activation 下载免费PDF全文
Dr. Wissam Iali Dr. Pierre‐Henri Lanoe Dr. Stéphane Torelli Dr. Damien Jouvenot Prof. Frédérique Loiseau Colette Lebrun Dr. Olivier Hamelin Dr. Stéphane Ménage 《Angewandte Chemie (International ed. in English)》2015,54(29):8415-8419
Dioxygen activation by copper complexes is a valuable method to achieve oxidation reactions for sustainable chemistry. The development of a catalytic system requires regeneration of the CuI active redox state from CuII. This is usually achieved using extra reducers that can compete with the CuII(O2) oxidizing species, causing a loss of efficiency. An alternative would consist of using a photosensitizer to control the reduction process. Association of a RuII photosensitizing subunit with a CuII pre‐catalytic moiety assembled within a unique entity is shown to fulfill these requirements. In presence of a sacrificial electron donor and light, electron transfer occurs from the RuII center to CuII. In presence of dioxygen, this dyad proved to be efficient for sulfide, phosphine, and alkene catalytic oxygenation. Mechanistic investigations gave evidence about a predominant 3O2 activation pathway by the CuI moiety. 相似文献
4.
Energetic 2,2‐Dimethyltriazanium Salts: A New Family of Nitrogen‐Rich Hydrazine Derivatives 下载免费PDF全文
Dr. Valérian Forquet Dr. Carlos Miró Sabaté Dr. Guy Jacob Dr. Yann Guelou Dr. Henri Delalu Dr. Chaza Darwich 《化学:亚洲杂志》2015,10(8):1668-1675
Amination of 1,1‐dimethylhydrazine with NH2Cl or hydroxylamine‐O‐sulfonic acid yields 2,2‐dimethyltriazanium (DMTZ) chloride ( 3 ) and sulphate ( 4 ), respectively. The DMTZ cation was paired with the nitrogen‐rich anions 5‐aminotetrazolate ( 5 ), 5‐nitrotetrazolate ( 6 ), 5,5′‐azobistetrazolate ( 7 ), and azide ( 8 ), yielding a new family of energetic salts. The synthesis was carried out by metathesis reactions of salts 3 or 4 and a suitable silver or barium salt. To minimize the risks involved when using heavy metal salts, we used electrodialysis for the synthesis of azide 8 , which avoids the use of highly sensitive species. The DMTZ derivatives were characterized by IR and multinuclear NMR spectroscopy, elemental analysis, and X‐ray diffraction. Thermal stabilities were measured using DSC analysis and their sensitivities towards classical stimuli were determined using standard tests. Lastly, the relationship between hydrogen bonding in the solid state and sensitivity is discussed. 相似文献
5.
Takashi Tsuno Yu Sugiyama Henri Brunner Michael Bodensteiner Kosei Lee 《Journal of Coordination Chemistry》2017,70(20):3459-3470
Treatment of NiCl2 with the tripod ligand (LMent,SC)-1H led to (LMent,SC)-[Cp(PNMent)NiCl] in which the potentially tridentate ligand coordinated to the metal center in a bidentate way via the cyclopentadienyl system and the phosphorus atom. In the presence of NH4PF6 [(LMent,SC)-[Cp(PNMent)NiCl] readily underwent Cl/PPh3 exchange to give (LMent,SC)-[Cp(PNMent)NiPPh3]PF6. Reaction of (LMent,SC)-[Cp(PNMent)NiCl] with 0.5 eq. of dppe afforded [{(LMent,SC)-[Cp(PNMent)Ni]}2dppe](PF6)2. (LMent,SC)-[Cp(PNMent)NiPPh3]PF6 and [{(LMent,SC)-[Cp(PNMent)Ni]}2dppe](PF6)2 were characterized by NMR and MS spectroscopy, and also by single crystal X-ray diffraction. The cyclopentadienyl ligand of (LMent,SC)-[Cp(PNMent)NiPPh3]PF6 shows a distortion intermediate between the ene-allyl and diene types, while the two cyclopentadienyl ligands of [{(LMent,SC)-[Cp(PNMent)Ni]}2dppe](PF6)2 have intermediate and diene distortions, respectively. According to the temperature dependent NMR spectra of (LMent,SC)-[Cp(PNMent)NiPPh3]PF6 and [{(LMent,SC)-[Cp(PNMent)Ni]}2dppe](PF6)2 two different conformations of the tether in the Cp(PNMent)Ni system could be frozen out at low temperatures. 相似文献
6.
Audrey Llevot Etienne Grau Stphane Carlotti Stphane Grelier Henri Cramail 《Macromolecular rapid communications》2016,37(1):9-28
Nowadays, the synthesis of (semi)aromatic polymers from lignin derivatives is of major interest, as aromatic compounds are key intermediates in the manufacture of polymers and lignin is the main source of aromatic biobased substrates. Phenols with a variety of chemical structures can be obtained from lignin deconstruction; among them, vanillin and ferulic acid are the main ones. Depending on the phenol substrates, different chemical modifications and polymerization pathways are developed, leading to (semi)aromatic polymers covering a wide range of thermomechanical properties. This review discusses the synthesis and properties of thermosets (vinyl ester resins, cyanate ester, epoxy, and benzoxazine resins) and thermoplastic polymers (polyesters, polyanhydrides, Schiff base polymers, polyacetals, polyoxalates, polycarbonates, acrylate polymers) prepared from vanillin, ferulic acid, guaiacol, syringaldehyde, or 4‐hydroxybenzoic acid.
7.
Daniel Desbordes Henri Noël Presles Franckie Joubert Cresus Gbagdo Douala 《Comptes Rendus Mecanique》2004,332(12):993-999
Calculations of the detonation reaction zone of gaseous H2NO2/N2O4 mixtures in the range of equivalence ratio Φ between 0.25 and 0.7 show that for 0.25Φ0.4 the chemical energy is released in two distinct and successive exothermic steps characterised by different chemical characteristic times. As for rich mixtures, the first exothermic step is mainly due to the reaction NO2 + H → NO + OH, but the second one is different since it results from the exothermic decomposition of NO into N2 and O2. For Φ=0.3 the measured detonation velocity in a tube of 52 mm internal diameter is very much smaller than the calculated value and the mean size of the cellular structure is very much larger than the value extrapolated from data obtained with mixtures of higher but close equivalence ratio. All these results show that the detonation, though self-sustained and steady, is ‘non-ideal’, i.e. it is supported only by a part of the available chemical energy, that provided mainly by the first exothermic step. To cite this article: D. Desbordes et al., C. R. Mecanique 332 (2004). 相似文献
8.
Henri Bertin Michel Quintard Ph. Vincent Corpel Stephen Whitaker 《Transport in Porous Media》1990,5(6):543-590
Two-phase flow in stratified porous media is a problem of central importance in the study of oil recovery processes. In general, these flows are parallel to the stratifications, and it is this type of flow that we have investigated experimentally and theoretically in this study. The experiments were performed with a two-layer model of a stratified porous medium. The individual strata were composed of Aerolith-10, an artificial: sintered porous medium, and Berea sandstone, a natural porous medium reputed to be relatively homogeneous. Waterflooding experiments were performed in which the saturation field was measured by gamma-ray absorption. Data were obtained at 150 points distributed evenly over a flow domain of 0.1 × 0.6 m. The slabs of Aerolith-10 and Berea sandstone were of equal thickness, i.e. 5 centimeters thick. An intensive experimental study was carried out in order to accurately characterize the individual strata; however, this effort was hampered by both local heterogeneities and large-scale heterogeneities.The theoretical analysis of the waterflooding experiments was based on the method of large-scale averaging and the large-scale closure problem. The latter provides a precise method of discussing the crossflow phenomena, and it illustrates exactly how the crossflow influences the theoretical prediction of the large-scale permeability tensor. The theoretical analysis was restricted to the quasi-static theory of Quintard and Whitaker (1988), however, the dynamic effects described in Part I (Quintard and Whitaker 1990a) are discussed in terms of their influence on the crossflow.Roman Letters
A
interfacial area between the -region and the -region contained within V, m2
-
a
vector that maps
onto
, m
-
b
vector that maps
onto
, m
-
b
vector that maps
onto
, m
-
B
second order tensor that maps
onto
, m2
-
C
second order tensor that maps
onto
, m2
-
E
energy of the gamma emitter, keV
-
f
fractional flow of the -phase
- g
gravitational vector, m/s2
-
h
characteristic length of the large-scale averaging volume, m
-
H
height of the stratified porous medium
, m
-
i
unit base vector in the x-direction
-
K
local volume-averaged single-phase permeability, m2
-
K - {K}, large-scale spatial deviation permeability
-
{
K}
large-scale volume-averaged single-phase permeability, m2
-
K
*
large-scale single-phase permeability, m2
-
K
**
equivalent large-scale single-phase permeability, m2
-
K
local volume-averaged -phase permeability in the -region, m2
-
K
local volume-averaged -phase permeability in the -region, m2
-
K
- {K
}
, large-scale spatial deviation for the -phase permeability, m2
-
K
*
large-scale permeability for the -phase, m2
-
l
thickness of the porous medium, m
-
l
characteristic length for the -region, m
-
l
characteristic length for the -region, m
-
L
length of the experimental porous medium, m
-
characteristic length for large-scale averaged quantities, m
-
n
outward unit normal vector for the -region
-
n
outward unit normal vector for the -region
-
n
unit normal vector pointing from the -region toward the -region (n
= - n
)
-
N
number of photons
-
p
pressure in the -phase, N/m2
-
p
0
reference pressure in the -phase, N/m2
-
local volume-averaged intrinsic phase average pressure in the -phase, N/m2
-
large-scale volume-averaged pressure of the -phase, N/m2
-
large-scale intrinsic phase average pressure in the capillary region of the -phase, N/m2
-
-
, large-scale spatial deviation for the -phase pressure, N/m2
- pc
, capillary pressure, N/m2
-
p
c
capillary pressure in the -region, N/m2
-
p
capillary pressure in the -region, N/m2
- {p
c
}
c
large-scale capillary pressure, N/m2
-
q
-phase velocity at the entrance of the porous medium, m/s
-
q
-phase velocity at the entrance of the porous medium, m/s
- Swi
irreducible water saturation
-
S
/, local volume-averaged saturation for the -phase
-
S
i
initial saturation for the -phase
-
S
r
residual saturation for the -phase
-
S
*
{
}*/}*, large-scale average saturation for the -phase
-
S
saturation for the -phase in the -region
-
S
saturation for the -phase in the -region
-
t
time, s
-
v
-phase velocity vector, m/s
- v
local volume-averaged phase average velocity for the -phase, m/s
- {v
}
large-scale averaged velocity for the -phase, m/s
- v
local volume-averaged phase average velocity for the -phase in the -region, m/s
- v
local volume-averaged phase average velocity for the -phase in the -region, m/s
-
v
-{v
}
, large-scale spatial deviation for the -phase velocity, m/s
-
v
-{v
}
, large-scale spatial deviation for the -phase velocity in the -region, m/s
-
v
-{v
}
, large-scale spatial deviation for the -phase velocity in the -region, m/s
-
V
large-scale averaging volume, m3
-
y
position vector relative to the centroid of the large-scale averaging volume, m
- {y}c
large-scale average of y over the capillary region, m
Greek Letters
local porosity
-
local porosity in the -region
-
local porosity in the -region
-
local volume fraction for the -phase
-
local volume fraction for the -phase in the -region
-
local volume fraction for the -phase in the -region
- {}*
{
}*+{
}*, large-scale spatial average volume fraction
- {
}*
large-scale spatial average volume fraction for the -phase
-
mass density of the -phase, kg/m3
-
mass density of the -phase, kg/m3
-
viscosity of the -phase, N s/m2
-
viscosity of the -phase, Ns/m2
-
V
/V
, volume fraction of the -region (
+
=1)
-
V
/V
, volume fraction of the -region (
+
=1)
-
attenuation coefficient to gamma-rays, m-1
-
-
相似文献
9.
Manqi Ruan Hang Zhao Gang Li Chengdong Fu Zhigang Wang Xinchou Lou Dan Yu Vincent Boudry Henri Videau Vladislav Balagura Jean-Claude Brient Peizhu Lai Chia-Ming Kuo Bo Liu Fenfen An Chunhui Chen Soeren Prell Bo Li Imad Laketineh 《The European Physical Journal C - Particles and Fields》2018,78(5):426
After the Higgs discovery, precise measurements of the Higgs properties and the electroweak observables become vital for the experimental particle physics. A powerful Higgs/Z factory, the Circular Electron Positron Collider (CEPC) is proposed. The Particle Flow oriented detector design is proposed to the CEPC and a Particle Flow algorithm, Arbor is optimized accordingly. We summarize the physics object reconstruction performance of the Particle Flow oriented detector design with Arbor algorithm and conclude that this combination fulfills the physics requirement of CEPC. 相似文献
10.