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941.
942.
943.
Serial MR imaging of intracranial metastases after radiosurgery 总被引:1,自引:0,他引:1
Hans Hawighorst Marco Essig Jürgen Debus Michael V. Knopp Rita Engenhart-Cabilic S.O. Schönberg Gunnar Brix Ivan Zuna Gerhard van Kaick 《Magnetic resonance imaging》1997,15(10):1121-1132
Purpose: To evaluate the spatiotemporal evolution of radiosurgical induced changes both in metastases and in normal brain tissue adjacent to the lesions by serial magnetic resonance (MR) imaging. Methods and Materials: Thirty-five intracranial metastases of different primaries were treated in 25 patients by single high-dose radiosurgery. MR images acquired before radiosurgery were available in all patients. Sixty-three follow-up MR studies were performed in these patients including T2- and contrast-enhanced T1-weighted MR images. The average follow-up time was 9 ± 5 months (mean ± standard deviation [SD]). Based on contrast-enhanced T1-weighted MR images, tumor response was radiologically classified in the following four groups: stable disease was assumed if the average tumor diameter after treatment did not show a tumor shrinkage of more than 50% and an increase of more than 25%, partial remission as a shrinkage of tumor size of more than 50%, a disappearance of contrast-enhancing tumor as a complete remission, and an increase of tumor diameter of more than 25% as tumor progress. Moreover, we analysed signal changes on T2-weighted images in brain parenchyma adjacent to the enhancing metastases. Results: The overall mean survival time was 10.5 ± 7 months, with a 1-year actuarial survival rate of 40%. Stable disease, partial or complete remission of the metastatic tumor was observed in 22 patients (88%). Central or homogeneous loss of contrast enhancement appeared to be a good prognostic sign for stable disease or partial remission. This association was statistically significant (p < 0.05). Three patients (12%) suffered from tumor progression. In eight patients (32%) with stable disease or partial remission, signal changes on T2-weighted images were observed in tissue adjacent to the contrast enhancing lesions. A progression of the high signal on T2-weighted images was seen in seven of the eight patients between 3 and 6 months after therapy, followed by a signal regression 6–18 months after irradiation. Conclusion: MR imaging is a sensitive imaging tool to evaluate tumor response as well as the presence or absence of adjacent parenchymal changes following radiosurgery. Loss of homogeneous or central contrast enhancement on Gd-enhanced MR images appeared to be a good prognostic sign for tumor response. Tumor shrinkage seems not to be dependent on time. In addition, most cases of radiation induced changes in normal brain parenchyma observed on T2-weighted images seem to be self limited. 相似文献
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945.
Gerhard Sorg Anne Mengel Günther Jung Jrg Rademann 《Angewandte Chemie (International ed. in English)》2001,40(23):4395-4397
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947.
Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes XXI The Influence of the PR3 Ligands on Formation and Properties of the Phosphinophosphinidene Complexes [{η2‐tBu2P–P}Pt(PR3)2] and [{η2‐tBu2P1–P2}Pt(P3R3)(P4R′3)] (R3P)2PtCl2 and C2H4 yield the compounds [{η2‐C2H4}Pt(PR3)2] (PR3 = PMe3, PEt3, PPhEt2, PPh2Et, PPh2Me, PPh2iPr, PPh2tBu and P(p‐Tol)3); which react with tBu2P–P=PMetBu2 to give the phosphinophosphinidene complexes [{η2‐tBu2P–P}Pt(PMe3)2], [{η2‐tBu2P–P}Pt(PEt3)2], [{η2‐tBu2P–P}Pt(PPhEt2)2], [{η2‐tBu2P–P}Pt(PPh2Et)2], [{η2‐tBu2P–P}Pt(PPh2Me)2], [{η2‐tBu2P–P}Pt(PPh2iPr], [{η2‐tBu2P–P}Pt(PPh2tBu)2] and [{η2‐tBu2P–P}Pt(P(p‐Tol)3)2]. [{η2‐tBu2P–P}Pt(PPh3)2] reacts with PMe3 and PEt3 as well as with tBu2PMe, PiPr3 and P(c‐Hex)3 by substituting one PPh3 ligand to give [{η2‐tBu2P1–P2}Pt(P3Me3)(P4Ph3)], [{η2‐tBu2P1–P2}Pt(P3Ph3)(P4Me3)], [{η2‐tBu2P1–P2}Pt(P3Et3)(P4Ph3)], [{η2‐tBu2P1–P2}Pt(P3MetBu2)(P4Ph3)], [{η2‐tBu2P1–P2}Pt(P3iPr3)(P4Ph3)] and [{η2‐tBu2P1–P2}Pt(P3(c‐Hex)3)(P4Ph3)]. With tBu2PMe, [{η2‐tBu2P–P}Pt(P(p‐Tol)3)2] forms [{η2‐tBu2P1–P2}Pt(P3MetBu2)(P4(p‐Tol)3)]. The NMR data of the compounds are given and discussed with respect to the influence of the PR3 ligands. 相似文献
948.
Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XX Formation and Structure of [{η2‐tBu2P–P}Pt(PHtBu2)(PPh3)] [{η2‐tBu2P1–P2}Pt(P3Ph3)(P4Ph3)] ( 2 ) reacts with tBu2PH exchanging only the P3Ph3 group to give [{η2‐tBu2P1–P2}Pt(P3HtBu2)(P4Ph3)] ( 1 ). The crystal stucture determination of 1 together with its 31P{1H} NMR data allow for an unequivocal assignment of the coupling constants in related Pt complexes. 1 crystallizes in the triclinic space group P1 (no. 2) with a = 1030.33(15), b = 1244.46(19), c = 1604.1(3) pm, α = 86.565(17)°, β = 80.344(18)°, γ = 74.729(17)°. 相似文献
949.
950.
Oskar Friedrich Olaj Andreas Kornherr Gerhard Zifferer 《Macromolecular theory and simulations》2000,9(3):131-140
On the basis of simulated data two ways of evaluating individual rate constants by combining kp2/kt and kp /kt (kp , kt = rate constants of chain propagation and termination, respectively) were checked considering the chain‐length dependence of kt. The first way tried to make use of the fact that pseudostationary polymerization yields data for kp2/kt as well as for kp /kt referring to the very same experiment, in the second way kp2/kt (from steady state experiments) and kp/kt data referring to the same mean length of the terminating radical chains were compared. In the first case no meaningful data at all could be obtained because different averages of kt are operative in the expressions for kp /kt and kp2/kt. In spite of the comparatively small difference between these two averages (≈15% only) this makes the method collapse. The second way, which can be regarded as an intelligent modification of the “classical” method of determining individual rate constants, at least succeeded in reproducing the correct order of magnitude of the individual rate constants. However, although stationary and pseudostationary experiments independently could be shown to return the same kt for the same average chain‐length of terminating radicals within extremely narrow limits no reasonable chain‐length dependence of kt could be derived in this way. The reason is an extreme sensitivity of the pair of equations for kp/kt and kp2/kt towards small errors and inconsistencies which renders the method unsuccessful even for the high quality simulation data and most probably makes it even collapse for real data. This casts a characteristic light on the unsatisfactory situation with respect to individual rate constants determined in the classical way, regardless of a chain‐length dependence of termination. As a consequence, all efforts of establishing the chain‐length dependence of kt are recommended to avoid this way and should rather resort to methods based on inserting a directly determined kp into the equations characteristic of kp2/kt or kp/kt, properly considering the chain‐length dependent character of kt. 相似文献