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41.
Stephen L. Howard Joyce E. Newberry Rosario C. Sausa Andrzej W. Miziolek 《Journal of the American Society for Mass Spectrometry》1993,4(2):152-158
A recently developed research apparatus for characterization of low-pressure premixed flames has been developed and was used to characterize the C2H4/N2O/Ar flame at 20 torr. This instrument incorporates several diagnostic techniques in one apparatus so that individual techniques can be quantitatively compared and the usable detection range (both in terms of resolution and species detection) expanded. Results discussed in this report include mass analysis by triple quadrupole mass spectrometer and temperature measurement by thermocouple. Concentration profiles in the one-dimensional flame include CO, N2, and C2H4, at nominal m/z 28 as well as CO2 and N2O at m/z 44. 相似文献
42.
43.
MCl5 (M = Nb, Ta) reacts with 2 equivalents of Me3SiNHCMe3 to give [M(NCMe3)Cl3(NH2CMe3)] from which [M(NCMe3)Cl3(PMe3)2] is obtained on addition of PMe3. One equivalent of Me3SiNHCMe3 reacts with MCl5 in the presence of 3 equivalents of PMe3 to give [M(NCMe3)Cl3(PMe3)2] and PMe3HCl. MCl5 reacts with excess RNH2 (R = CMe3, CHMe2, CH2Me) to give [M(NR)(NHR)Cl2(NH2R)] and 3 equivalents of RNH3Cl. One equivalent of alcohol replaces the amido ligand in [M(NCMe3)(NHCMe3)Cl2(NH2CMe3)] to give [M(NCMe3)(OR)Cl2(NH2CMe3)]2 (M = Nb, R = OCMe3; M = Ta, R = OEt). The structure of [Ta(NCMe3)(μ-OEt)Cl2(NH2CMe3)]2 was determined by single-crystal X-ray diffraction methods. Crystals are triclinic, space group P with a = 9.900(5), b = 10. 161(17), c = 9.017(6) Å and α = 103.91(8), β = 97.77(4), γ = 64.40(7)°. The structure was solved by Patterson and Fourier methods and refined to an R value of 0.062 for 1319 observed data. The TaNimido and TaNamino bond lengths are 1.70(2) Å and 2.28(2) Å, respectively; the bridging TaO bond lengths are 2.01(2) Å and 2.32(2) Å, the longer one lying trans to the imido function. 相似文献
44.
Zusammenfassung Actinomycin D (250 /ml) hemmt in Suspensionskulturen vonPhysarum polycephalum spezifisch die RNS-Synthese, während die DNS- und Proteinsynthese innerhalb der ersten drei Stunden nur wenig beeinträchtigt werden. Die Auslösung einer synchronen Kernteilung in Makroplasmodien kann durch 250 /ml Actinomycin D verhindert oder stark verzögert werden, sofern der Hemmstoff spätestens zu Beginn des letzten Drittels der Interphase ( 2 Stdn. vor Prophase) dem Medium zugesetzt wird. Die Mitosehemmung ist durch Auswaschen des Hemmstoffes reversibel. Die Ergebnisse sprechen dafür, daß zur Vorbereitung einer Mitose während des größten Teiles der Interphase DNS-abhängige RNS neu gebildet werden muß, die möglicherweise als Informationsüberträger die Synthese mitosespezifischer Proteine kontrolliert. Es wird eine Arbeitshypothese diskutiert, nach der die Mitose als ein durch Genregulation gesteuerter Vorgang aufzufassen wäre.
Mit 4 Abbildungen
Herrn Prof. Dr.Hermann Bretschneider zum 60. Geburtstag gewidmet. 相似文献
Actinomycin D (250 /ml) specifically inhibits RNA synthesis in suspension cultures ofPhysarum polycephalum whereas DNA and protein synthesis are less affected within the first three hours. Onset of synchronous mitoses in macroplasmodia is prohibited or largely delayed by 250 /ml actinomycin D if the inhibitor is added to the medium at or prior to the beginning of the last third of interphase ( 2 hrs. prior to prophase). Removal of the inhibitor from the medium reverses the inhibitory effect on mitosis. The results indicate that preparation of mitosis requires synthesis of DNA dependent RNA during the major part of interphase. These RNA molecules possibly carry information for the synthesis of proteins specifically involved with mitosis. A working hypothesis is discussed suggesting that mitotic activities may by controlled by gene regulation.
Mit 4 Abbildungen
Herrn Prof. Dr.Hermann Bretschneider zum 60. Geburtstag gewidmet. 相似文献
45.
Reaction of phenylimido tungsten tetrachloride with MeOH and t-butylamine gave the dimeric complexes [W(NPh)(μ-OMe)(OMe)3]2 and [W(NPh)(μ-OMe)(OMe)2Cl]2. With ethanol [W(NPh)(μ-OEt)(OEt)2Cl]2 was formed whereas isopropyl and neopentyl alcohols gave the monomeric complexes [W(NPh)(OR)4(NH2CMe3)](R = CHMe2, CH2CMe3); t-butanol gave [W(NPh)(OCMe3)3Cl(NH2CMe3)] which could not be converted to [W(NPh) (OCMe3)4]. Further reaction of [W(NPh)(μ-OMe)(OMe)3]2 with o-HOC6H4CH = NC6H3Me2(salim-H) gave the salicylaldimine complex [W(NPh)(OMC)3(salim)]. The products were characterised by analytical data, IR, 1H NMR, 13C NMR and mass spectroscopy. The crystal and molecular structures of the title complexes have been determined from single crystal X-ray diffractometer data. Crystals of [W(NPh)(μ-OMe)(OMe)3]2are triclinic with a = 8.473(7), b = 10.776(5), c = 7.683(Å, α = 102.26(3), β = 102.68(4), γ = 71.13(6)°, space group P Crystals of 3) [W(NPh)(OCMe3)3Cl(NH2CMe3) are monoclinic with a = 9.341(2), b = 29.608(7), c = 10.257(2) Å, β = 106.28(2)°, space group, P21/c. Both structures were solved by Patterson and Fourier methods and refined to R = 0.075 for the 1022 observed data of [W(NPh) (μ-OMe)(OMe)3]2 and to R = 0.074. For the 2033 observed data of [W(NPh)(OCMe3)3Cl(NH2CMe3). The former molecule is shown to be a dimer, the two halves of the molecule being related by a centre of symmetry. Both W atoms adopt a distorted octahedral coordination geometry and they are linked by two methoxy bridges. Trans to one of the bridging donors is the phenyl imido group with a WN bond length of 1.61(4) Å; the remaining coordination sites are filled with methoxy groups. The structure of W(NPh)(OCMe3)3 Cl(NH2CMe3) is monomeric with the phenylimido group trans to the NH2CMe3 ligand in a distorted octahedral coordination geometry. Remaining sites are filled with the chloride and 3 OCMe3 ligands. The WN (imido) bond length is 1.71(2) Å, whilst WN(amine) is 2.40(2) Å 相似文献
46.
47.
Potential for the use of ultrasound in the extraction of antioxidants from Rosmarinus officinalis for the food and pharmaceutical industry 总被引:7,自引:0,他引:7
Ultrasound was used to increase the extraction efficiency of carnosic acid from the herb Rosmarinus officinalis using butanone, ethyl acetate and ethanol as solvents. Both dried and fresh leaves of the herb were extracted and, when performed at the same temperature, sonication improved the yields of carnosic acid for all three solvents and shortened the extraction times. Sonication also reduced the solvent effect so that ethanol, which is a poor solvent under conventional conditions, reached a similar level of extraction efficiency to the other two when sonicated. The extraction of dried herb with ethanol proved to be more efficient than that of fresh material, probably due to the water present in the latter. 相似文献
48.
Special Lagrangian Submanifolds with Isolated Conical Singularities. II. Moduli spaces 总被引:1,自引:1,他引:0
This is the second in a series of five papers studying special Lagrangiansubmanifolds (SLV m-folds) X in (almost) Calabi–Yau m-folds
M with singularities x
1
, ..., x
n
locally modelled on specialLagrangian cones
C
1, ..., C
n
in
m
with isolated singularities at 0.Readers are advised to begin with Paper V.This paper studies the deformation theory of compact SL m-folds X in Mwith conical singularities. We define the moduli space
X
of deformations of X in M, and construct a natural topology on it. Then we show that
X
is locally homeomorphic to the zeroes of a smooth map :
X
X between finite-dimensional vector spaces.Here the infinitesimal deformation space
X depends only on the topology of X, and the obstruction space
X only on the cones C
1, ..., C
n
at x
1, ..., x
n
. If the cones C
i
are stable then
X is zero, and
X
is a smooth manifold. We also extend our results to families of almost Calabi–Yau structures on M. 相似文献
49.
Dominic D. Joyce 《Annals of Global Analysis and Geometry》2001,20(4):345-403
This is the third in a series of papers constructing explicit examples of special Lagrangian submanifolds in C
m
. The previous paper (Math. Ann.
320 (2001), 757–797), defined the idea of evolution data, which includes an (m – 1)-submanifold P in R
n
, and constructed a family of special Lagrangian m-folds N in C
m
, which are swept out by the image of P under a 1-parameter family of affine maps
t
: R
n
C
m
, satisfying a first-order o.d.e. in t. In this paper we use the same idea to construct special Lagrangian 3-folds in C3. We find a one-to-one correspondence between sets of evolution data with m = 3 and homogeneous symplectic 2-manifolds P. This enables us to write down several interesting sets of evolution data, and so to construct corresponding families of special Lagrangian 3-folds in C3.Our main results are a number of new families of special Lagrangian 3-foldsin C3, which we write very explicitly in parametric form. Generically these are nonsingular as immersed 3-submanifolds, and diffeomorphic to R3 or
1× R2. Some of the 3-folds are singular, and we describe their singularities, which we believe are of a new kind.We hope these 3-folds will be helpful in understanding singularities ofcompact special Lagrangian 3-folds in Calabi–Yau 3-folds. This will beimportant in resolving the SYZ conjecture in Mirror Symmetry. 相似文献
50.
Smita A Ghanekar Sonny Bhatia Joyce J Ruitenberg DeLa Corazon Rosa Mary L Disis Vernon C Maino Holden T Maecker Cory A Waters 《Journal of immune based therapies and vaccines》2007,5(1):7-14