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61.
D. T. Asilbekova 《Chemistry of Natural Compounds》2003,39(5):442-445
Lipids from fruit pulp of the sweet red pepper (Capsicum annuum, Solanaceae) were characterized. The principal components of the lipids from pepper fruit pulp were neutral lipids with predominance of triacylglycerines (55.8%). The polar lipids contained sulfoquinovosyldiacylglycerines and phosphotidylglycerines. The fatty-acid compositions of the neutral lipids, glycolipids, and phospholipids were determined. 相似文献
62.
We have calculated the positions of the avoided level crossings between (n+2)s, np states and nd, k Stark states in the Rydberg Stark states of the potassium atom with principal quantum number n comprised between 12 and 17. We have also studied the adiabatic electric field ionization thresholds for the above Rydberg
states. Both the ionization thresholds and the positions of avoided crossings have been calculated using the recently developed
Stark-adapted quantum defect orbital (SQDO) formalism. The presently reported values appear to be in very good agreement with
the available theoretical and experimental data. 相似文献
63.
The complexity of different quality standards can, in principle, be covered by different approaches and strategies. In-depth
process mapping of quality control (QC) work streams was used by the analytical laboratories of Lonza AG to show up the principle
differences in being compliant to different quality systems. The results identified two main drivers for all necessary actions:
process-related activities and infrastructure-related activities. In addition, a clear indication of the economic impact of
these driving forces was gained, which led the laboratories to decide on a process-oriented approach. This approach has the
advantage of being able to reflect the different demands of different quality assurance (QA) regulations within the same QC
organizational structure. Following the process helps avoid unnecessary efforts in analytical work and represents a very economical
approach, at the same time, providing high flexibility to react to different QA or customer demands.
Received: 5 July 2002 Accepted: 12 November 2002
Acknowledgements The process-oriented approach resulted from many, very challenging discussions for which I would like to thank the staff
of my organization (Analytics & QC), especially, the QA staff and the LIMS team.
Presented at Analytica Conference, 23–26 April 2002, Munich, Germany
Correspondence to B. Ciommer 相似文献
64.
The graphical unitary group approach has been applied in an efficient implementation of a general multireference configuration interaction (MRCI) method for use with small active molecular orbital spaces in a semiempirical framework. Gradients can be computed analytically for molecular orbitals from a closed-shell or a half-electron open-shell Hartree-Fock calculation. CPU times for single point energy and gradient calculations are reported. The code allows MRCI geometry optimizations of large molecules, as illustrated for the singlet ground state and the four lowest triplet states of fullerene C(76). 相似文献
65.
Quan Zheng 《European Polymer Journal》2006,42(4):807-814
Two dendritic reversible addition-fragmentation transfer (RAFT) agents with 8 and 16 terminal dithiobenzoate (DTB) groups on the surface of poly(propylene imine) (PPI) dendrimers (generation 2.0 and 3.0, respectively) were successively prepared, and they were used in the RAFT polymerization of N-isopropylacrylamide (NIPAAM). The polymerization kinetics was confirmed to pseudo-first-order behavior. The 1H NMR and GPC analyses show that the dendrimer-star den (NIPAAM)x (x = 8 or 16) prepared by RAFT method has well-defined structure, controlled molecular weight and low polydispersities (PDI < 1.3). The aqueous solution prepared from dendrimer-star PNIPAAM showed reversible changes in optical properties: transparent below a lower critical solution temperature (LCST) and opaque above the LCST. 相似文献
66.
In this research work, we deal with the stabilization of uncertain fractional-order neutral systems with delayed input. To tackle this problem, the guaranteed cost control method is considered. The purpose is to design a proportional–differential output feedback controller to obtain a satisfactory performance. The stability of the overall system is described in terms of matrix inequalities, and the corresponding analysis is performed in the perspective of Lyapunov’s theory. Two application examples verify the analytic findings. 相似文献
67.
Dominique M. S. Buyens Lynne A. Pilcher Ignacy Cukrowski 《Molecules (Basel, Switzerland)》2022,27(18)
The adeninate anion (Ade−) is a useful nucleophile used in the synthesis of many prodrugs (including those for HIV AIDS treatment). It exists as a contact ion-pair (CIP) with Na+ and K+ (M+) but the site of coordination is not obvious from spectroscopic data. Herein, a molecular-wide and electron density-based (MOWED) computational approach implemented in the implicit solvation model showed a strong preference for bidentate ion coordination at the N3 and N9 atoms. The N3N9-CIP has (i) the strongest inter-ionic interaction, by −30 kcal mol−1, with a significant (10–15%) covalent contribution, (ii) the most stabilized bonding framework for Ade−, and (iii) displays the largest ion-induced polarization of Ade−, rendering the N3 and N9 the most negative and, hence, most nucleophilic atoms. Alkylation of the adeninate anion at these two positions can therefore be readily explained when the metal coordinated complex is considered as the nucleophile. The addition of explicit DMSO solvent molecules did not change the trend in most nucleophilic N-atoms of Ade− for the in-plane M-Ade complexes in M-Ade-(DMSO)4 molecular systems. MOWED-based studies of the strength and nature of interactions between DMSO solvent molecules and counter ions and Ade− revealed an interesting and unexpected chemistry of intermolecular chemical bonding. 相似文献
68.
Metalaxyl-M and azoxystrobin have been used to control various fungal diseases on scallion and other crops. In view of the adverse toxic effects of both on the mammalian liver, it is necessary to conduct a cumulative risk assessment of their dietary exposure to consumers. The residues of metalaxyl-M and azoxystrobin on scallion were determined by a quick, easy, cheap, effective, rugged, and safe method (QuEChERS) combined with high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS). The half-lives were about 1.15 and 3.89 days, respectively, and the final residues after a seven-day harvest interval were <0.001–0.088 mg/kg and 0.190–4.687 mg/kg, respectively. The cumulative dietary risk quotient of the two fungicides to Chinese consumers calculated by the probability model is 13.94%~41.25%. According to the results of the contribution analysis, the risk posed by azoxystrobin is much greater than that of metalaxyl-M. Although metalaxyl-M and azoxystrobin do not pose a cumulative risk to Chinese consumers, the risk to children and adolescents is significantly higher than that to adults. This suggests that in future research, more consideration should be given to the cumulative risk of compounds to vulnerable groups. 相似文献
69.
El-Sayed A. El-Sheikh Mahmoud M. Ramadan Ahmed E. El-Sobki Ali A. Shalaby Mark R. McCoy Ibrahim A. Hamed Mohamed-Bassem Ashour Bruce D. Hammock 《Molecules (Basel, Switzerland)》2022,27(22)
The use of pesticides leads to an increase in agricultural production but also causes harmful effects on human health when excessively used. For safe consumption, pesticide residues should be below the maximum residual limits (MRLs). In this study, the residual levels of pesticides in vegetables and fruits collected from farmers’ markets in Sharkia Governorate, Egypt were investigated using LC-MS/MS and GC-MS/MS. A total number of 40 pesticides were detected in the tested vegetable and fruit samples. Insecticides were the highest group in detection frequency with 85% and 69% appearance in vegetables and fruits, respectively. Cucumber and apple samples were found to have the highest number of pesticide residues. The mean residue levels ranged from 7 to 951 µg kg−1 (in vegetable samples) and from 8 to 775 µg kg−1 (in fruit samples). It was found that 35 (40.7%) out of 86 pesticide residues detected in vegetables and 35 (38.9%) out of 90 pesticide residues detected in fruits exceeded MRLs. Results for lambda-cyhalothrin, fipronil, dimothoate, and omethoate in spinach, zucchini, kaki, and strawberry, respectively, can cause acute or chronic risks when consumed at 0.1 and 0.2 kg day−1. Therefore, it is necessary for food safety and security to continuously monitor pesticide residues in fruits and vegetables in markets. 相似文献
70.