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991.
In this paper, we first give a direct construction of the ℕ-measure of a continuous state branching process. Then we prove,
with the help of this ℕ-measure, that any continuous state branching process with immigration can be constructed as the independent
sum of a continuous state branching process (without immigration), and two immigration parts (jump immigration and continuum
immigration). As an application of this construction of a continuous state branching process with immigration, we give a proof
of a necessary and sufficient condition, first stated without proof by M. A. Pinsky [Bull. Amer. Math. Soc., 1972, 78: 242–244],
for a continuous state branching process with immigration to a proper almost sure limit. As another application of the ℕ-measure,
we give a “conceptual” proof of an L log L criterion for a continuous state branching process without immigration to have an L
1-limit first proved by D. R. Grey [J. Appl. Prob., 1974, 11: 669–677]. 相似文献
992.
A conceptual model for microscopic-macroscopic slow-fast stochastic systems is considered. A dynamical reduction procedure is presented in order to extract effective dynamics for this kind of systems. Under appropriate assumptions, the effective system is shown to approximate the original system, in the sense of a probabilistic convergence. 相似文献
993.
994.
Zi‐Jing Li Hong‐Xiang Lou Wen‐Tao Yu Pei‐Hong Fan Dong‐Mei Ren Bin Ma Mei Ji 《Helvetica chimica acta》2005,88(10):2637-2640
The known 7,8‐secolabdane type diterpenoids neopallavicinin ( 1 ), pallavicinin ( 2 ), and 18‐hydroxypallavicinin ( 3 ) were isolated from Pallavicinia ambigua, and their structures were determined. The X‐ray crystal structure of 1 was solved, and, in combination with CD and NMR studies, the absolute configurations of 1 – 3 were established. A possible biogenetic pathway for 1 and 2 from a single labdane precursor is proposed. 相似文献
995.
Chao Wang Felix S. Kim Guoqiang Ren Yongqian Xu Yi Pang Samson A. Jenekhe Li Jia 《Journal of polymer science. Part A, Polymer chemistry》2010,48(21):4681-4690
Head‐to‐tail regioregular poly(3‐heptanoylthiophene) (PHOT) was synthesized by Ni‐catalyzed polycondensation of the 2,2‐dimethyl‐1,3‐propanediol‐protected Grignard monomer followed by deprotection. Cyclic voltammetric (CV) study demonstrates that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of PHOT are 0.5 eV lower in energy than those of the head‐to‐tail poly(3‐hexylthiophene) (HT‐P3HT). Their optical band gaps are essentially the same. Incomplete photoluminescence (PL) quenching was observed in thin films of the 1:1 blend of PHOT and HT‐P3HT. PHOT displayed a glass transition at ~269 °C and decomposed at ~300 °C according to differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Wide‐angle X‐ray diffraction (WAXD) study showed that PHOT exists in a not highly ordered state in solid films especially in the π‐stacking direction. Only p‐channel activity was observed in field‐effect transistors (FETs) for PHOT. The hole mobility was on the order of 10?4 cm2 V?1 s?1. Photovoltaic devices with an active layer of 1:1 blend of PHOT and PC71BM had a power conversion efficiency (PCE) of ~0.5%. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
996.
Kuo‐Chung Cheng Jiun‐Jeng Chen Wen‐Yen Chiu Lee Yih Wang Ping‐Chieh Wang 《Journal of polymer science. Part A, Polymer chemistry》2005,43(1):42-49
Dodecylbenzenesulfonic acid, DDBSA, was chosen as a new rate‐accelerating additive for 2,2,6,6,‐teramethyl‐1‐piperidinyloxy (TEMPO)‐mediated stable free radical polymerization of n‐butyl acrylate (n‐BA) monomers with 2,2′‐azobisisobutyronitrile (AIBN). It was found that the number‐average molecular weight of polymers could reach about ten thousand with a narrow polydispersity index (PDI) of 1.4 in a few minutes, which was faster than other systems reported previously. But, at higher conversion, the molecular weight distribution of polymers became broad, and a bimodal distribution occurred. The macro‐initiators isolated from the former polymers with narrow PDI could be extended by polymerization with monomers by the addition of DDBSA. Furthermore, a proposed kinetic model demonstrated that the decay of the concentration of DDBSA would reduce the living polymer concentration and retard the growth of the polymers, which could be further propagated by the supplement of DDBSA. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 42–49, 2005 相似文献
997.
Chang‐Yin Li Lian‐Wen Qi Ping Li Xiao‐Dong Wen Yan‐Fei Zhu E‐Hu Liu Zhen Gong Xiao‐Lin Yang Mei‐Ting Ren Yan‐Jing Li Xiao‐Xiao Ge 《Rapid communications in mass spectrometry : RCM》2009,23(13):1977-1988
A method coupling liquid chromatography with electrospray ionization time‐of‐flight mass spectrometry (LC/ESI‐TOF/MS) has been developed for rapid and sensitive analysis of rat urinary metabolite profile of Danggui Buxue Tang (DBT), a well‐known Chinese herbal formula. After oral administration of DBT, urine samples were collected during 0–24 h, and then pretreated by solid‐phase extraction. A total of 68 compounds including 13 parent compounds and 55 metabolites were detected in the drug‐containing urines compared with blank urines. The total analytical time was less than 20 min. Metabolites of DBT were identified using dynamic adjustment of the fragmentor voltage to produce structure‐relevant fragment ions. By using this approach, the mass accuracy of precursor and fragment ions was typically within ±5 ppm of the theoretical values, and enabled the identification of 43 metabolites including 27 isoflavanoid and 16 phthalide metabolites. Our results indicated that glucuronidation and sulfation were the major metabolic pathways of isoflavonoids, while glutathione conjugation, glucuronidation and sulfation were the main metabolic pathways of phthalides. No saponin‐related metabolites were detected. The results of the present study provided important structural information relating to the metabolism of DBT. Furthermore, this work demonstrated the potential of the LC/ESI‐TOF/MS approach for identification of metabolites from Chinese herbal medicines in urine. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
998.
The determination of the concentration of light elements, such as carbon, nitrogen and oxygen, in e.g. atmospheric aerosol
particles is important to study the chemical behaviour of atmospheric pollution. The knowledge of low-Z element concentrations gives us information on the speciation of nutrients (species having nutritional value for plants)
and toxic heavy metals in the particles. The capability of the conventional energy-dispersive EPMA is strongly limited for
the analysis of low-Z elements, mainly because the Be window in the EDX detector hinders the detection of characteristic X-rays of light elements
such as C, N, O and Na. WDS is suitable for analysis of light elements, but the measurement of beam sensitive microparticles
requires the minimisation of the beam current and the measurement time. A semi-quantitative analytical method based on EPMA
using an ultra-thin window EDX detector was developed. It was found that the matrix and geometric effects that are important
for low-energy X-rays can be reliably evaluated by Monte Carlo calculations. Therefore, the quantification part of the method
contains reverse Monte Carlo calculation done by iterative simulations. The method was standardised and tested by measurements
on single particles with known chemical compositions. Beam-sensitive particles such as ammonium-sulphate and ammonium-nitrate
were analysed using a liquid nitrogen cooled sample stage. The shape and size of the particles, which are important for the
simulations, were determined using a high-magnification secondary electron image. Individual marine aerosol particles collected
over the North Sea by a nine-stage Berner cascade impactor were analysed using this new method. Preliminary results on five
samples and 4500 particles show that the method can be used to study the modification of sea-salt particles in the troposphere. 相似文献
999.
A. Stephen K. Hashmi Prof. Dr. Christian Lothschütz Dipl.‐Chem. Martin Ackermann Dipl.‐Chem. René Doepp Dipl.‐Chem. Sankaran Anantharaman Benjamin Marchetti Dipl.‐Chem. Helmut Bertagnolli Prof. Dr. Frank Rominger Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(27):8012-8019
Gold complexes were prepared and investigated as catalysts for the oxidative esterification of aldehydes. Stabilisation by pyridine ligands gave good conversions and the in situ extended X‐ray absorption fine structure (EXAFS) study of the reactions indicated that the reaction mixtures contained only mononuclear gold species. Thus, this is the first proof for a homogeneous gold‐catalysed oxidation reaction; the presence of nanoparticles could be excluded experimentally. 相似文献
1000.