全文获取类型
收费全文 | 27329篇 |
免费 | 2791篇 |
国内免费 | 1239篇 |
专业分类
耳鼻咽喉 | 61篇 |
儿科学 | 388篇 |
妇产科学 | 195篇 |
基础医学 | 3895篇 |
口腔科学 | 253篇 |
临床医学 | 2190篇 |
内科学 | 4087篇 |
皮肤病学 | 288篇 |
神经病学 | 1081篇 |
特种医学 | 592篇 |
外国民族医学 | 5篇 |
外科学 | 1300篇 |
综合类 | 4637篇 |
现状与发展 | 5篇 |
预防医学 | 2081篇 |
眼科学 | 311篇 |
药学 | 5665篇 |
11篇 | |
中国医学 | 2497篇 |
肿瘤学 | 1817篇 |
出版年
2024年 | 100篇 |
2023年 | 565篇 |
2022年 | 722篇 |
2021年 | 1414篇 |
2020年 | 1138篇 |
2019年 | 1014篇 |
2018年 | 922篇 |
2017年 | 1095篇 |
2016年 | 1172篇 |
2015年 | 1230篇 |
2014年 | 1691篇 |
2013年 | 2270篇 |
2012年 | 1616篇 |
2011年 | 1668篇 |
2010年 | 1310篇 |
2009年 | 1151篇 |
2008年 | 1263篇 |
2007年 | 1160篇 |
2006年 | 1099篇 |
2005年 | 1046篇 |
2004年 | 893篇 |
2003年 | 852篇 |
2002年 | 714篇 |
2001年 | 693篇 |
2000年 | 553篇 |
1999年 | 462篇 |
1998年 | 433篇 |
1997年 | 371篇 |
1996年 | 366篇 |
1995年 | 320篇 |
1994年 | 307篇 |
1993年 | 270篇 |
1992年 | 219篇 |
1991年 | 202篇 |
1990年 | 158篇 |
1989年 | 142篇 |
1988年 | 89篇 |
1987年 | 97篇 |
1986年 | 67篇 |
1985年 | 112篇 |
1984年 | 76篇 |
1983年 | 61篇 |
1982年 | 59篇 |
1981年 | 47篇 |
1980年 | 28篇 |
1979年 | 29篇 |
1978年 | 22篇 |
1977年 | 17篇 |
1976年 | 24篇 |
1975年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
991.
992.
Optical coherence tomography derived differences of plaque characteristics in coronary culprit lesions between type 2 diabetic patients with and without acute coronary syndrome 下载免费PDF全文
993.
Javier de Miguel-Díez Rodrigo Jiménez-García Valentín Hernández-Barrera Luis Puente Maestu Irene Jarana Aparicio Alicia Oliva Ramos 《COPD》2014,11(4):459-467
Aims: To analyze clustering of unhealthy lifestyle behavior and its relationship with non-adherence to recommended clinical preventive care services among Spanish COPD patients. Methods: Cross-sectional study including 2,575 COPD subjects from the 2006 Spanish National Health Survey (NHS) and 2009 European Health Survey for Spain (EHISS). Subjects were asked about the following recommended preventive practices: uptake of blood pressure (BP) measurement, lipid profile, influenza vaccination and dental examination. Lifestyle behaviors included: smoking status, physical activity, alcohol consumption and obesity. Logistic regression models were built to assess the association between clustering of unhealthy lifestyle and the uptake of preventive activities. Results: Blood pressure measurement in the previous 6 months and a blood lipid test in the last year had not been taken by 11.74% and 23.26% of the subjects, respectively, in 2006 NHS and by 11.16% and 16.33% of the subjects, respectively, in EHISS 2009. Then, 36.36% percent had not been vaccinated and 70.61% had not received dental examination in 2006 NHS and these percentages decreased to 27.33% and 66.22%, respectively, in 2009 EHISS. A higher number of unhealthy lifestyle behaviors increased the probability of not being vaccinated and not having a dental examination. Clustering of unhealthy lifestyle behaviors is linearly associated with a greater number of preventive measures unfulfilled. Conclusions: Compliance with healthy lifestyles and adherence to recommended clinical preventive services is under desirable levels among Spanish COPD patients. Patients with lifestyles considered as “worse” are those who also have lower uptake of recommended preventive activities. 相似文献
994.
The asphalt mastic–aggregate interface plays an essential role in determining the service performance of asphalt mixtures. The objective of this paper was to investigate the adhesion behaviors and mechanism between asphalt mastic and aggregate based on molecular dynamic (MD) simulations. First, the asphalt mastic model considering the actual mass ratio of filler to asphalt (F/A) condition was established and validated in terms of thermodynamic properties. Second, the molecular arrangement characteristics of polar components on the aggregate substrate were analyzed by radial distribution function (RDF), relative concentration (RC), and mean square displacement (MSD). Third, the interfacial adhesion ability between asphalt and aggregate was quantitively evaluated based on the work of adhesion. Finally, the coupling effect of moisture and temperature on interfacial adhesion behaviors was investigated to explore the adhesion failure characteristics of the asphalt–aggregate interface. The results demonstrate that the thermodynamic properties could be employed to validate the reliability of the asphalt mastic model. The self-aggregation degree of polar components in base asphalt could be significantly increased with the addition of silica particles, exhibiting a change of configuration from “parallel arrangement” into “stack distribution” due to the high polarity of silica particles. The polar components in asphalt mastic exhibit a more uniform distribution state and lower mobility capability than base asphalt owing to the adsorption effect of silica particles. Silica particles with amounts of residual charges could significantly increase the electrostatic energy of the asphalt mastic–aggregate interface, contributing to an improvement of the adhesion between asphalt mastic and aggregate. The increase of temperature enhances the work of adhesion of the asphalt mastic–aggregate interface, which is opposite to that of the base asphalt–aggregate interface. The asphalt mastic exhibits a greater sensitivity to interfacial moisture damage than base asphalt. The findings would provide insights into a better understanding on the micro adhesion mechanism of the asphalt mastic–aggregate interface. 相似文献
995.
Recent studies have shown that the use of membranes based on artificial nanoporous materials can be effective for desalination and decontamination of water, separation of ions and gases as well as for solutions to other related problems. Before the expensive stages of synthesis and experimental testing, the search of the optimal dimensions and geometry of nanopores for the water desalination membranes can be done using computer-aided design. In the present study, we propose and examine the assumption that rectangular nanopores with a high aspect ratio would demonstrate excellent properties in terms of water permeation rate and ion rejection. Using the non-equilibrium molecular dynamic simulations, the properties of promising hexagonal boron nitride (h-BN) membranes with rectangular nanopores were predicted. It has been found that not only the nanopore width but also its design (“armchair” or “zigzag”) determines the permeability and ion selectivity of the h-BN-based membrane. The results show that membranes with a zigzag-like design of nanopores of ~6.5 Å width and the armchair-like nanopores of ~7.5 Å width possess better efficiency compared with other considered geometries. Moreover, the estimated efficiency of these membranes is higher than that of any commercial membranes and many other previously studied single-layer model membranes with other designs of the nanopores. 相似文献
996.
In the present work, modified embedded atom potential and large-scale molecular dynamics’ simulations were used to explore the effect of grain boundary (GB) segregated foreign interstitials on the deformation behavior of nanocrystalline (nc) iron. As a case study, carbon and nitrogen (about 2.5 at.%) were added to (nc) iron. The tensile test results showed that, at the onset of plasticity, grain boundary sliding mediated was dominated, whereas both dislocations and twinning were prevailing deformation mechanisms at high strain. Adding C/N into GBs reduces the free excess volume and consequently increases resistance to GB sliding. In agreement with experiments, the flow stress increased due to the presence of carbon or nitrogen and carbon had the stronger impact. Additionally, the simulation results revealed that GB reduction and suppressing GBs’ dislocation were the primary cause for GB strengthening. Moreover, we also found that the stress required for both intragranular dislocation and twinning nucleation were strongly dependent on the solute type. 相似文献
997.
998.
Jun Ding Sheng-Lai Zhang Quan Tong Lu-Sheng Wang Xia Huang Kun Song Shi-Qing Lu 《Materials》2020,13(24)
The effects of grain boundary misorientation angle (θ) on mechanical properties and the mechanism of plastic deformation of the Ni/Ni3Al interface under tensile loading were investigated using molecular dynamics simulations. The results show that the space lattice arrangement at the interface is dependent on grain boundary misorientations, while the interfacial energy is dependent on the arrangement. The interfacial energy varies in a W pattern as the grain boundary misorientation increases from 0° to 90°. Specifically, the interfacial energy first decreases and then increases in both segments of 0–60° and 60–90°. The yield strength, elastic modulus, and mean flow stress decrease as the interfacial energy increases. The mechanism of plastic deformation varies as the grain boundary misorientation angle (θ) increases from 0° to 90°. When θ = 0°, the microscopic plastic deformation mechanisms of the Ni and Ni3Al layers are both dominated by stacking faults induced by Shockley dislocations. When θ = 30°, 60°, and 80°, the mechanisms of plastic deformation of the Ni and Ni3Al layers are the decomposition of stacking faults into twin grain boundaries caused by extended dislocations and the proliferation of stacking faults, respectively. When θ = 90°, the mechanisms of plastic deformation of both the Ni and Ni3Al layers are dominated by twinning area growth resulting from extended dislocations. 相似文献
999.
1000.
C. Bettencourt J.L. López‐Sendón J. García‐Caldentey P. Rizzu I.M.C. Bakker O. Shomroni B. Quintáns J.R. Dávila M.R. Bevova M.‐J. Sobrido P. Heutink J.G. de Yébenes 《Clinical genetics》2014,85(2):154-158
Hereditary spastic paraplegias constitute a heterogeneous group of neurodegenerative diseases encompassing pure and complicated forms, for which at least 52 loci and 31 causative genes have been identified. Although mutations in the SPAST gene explain approximately 40% of the pure autosomal dominant forms, molecular diagnosis can be challenging for the sporadic and recessive forms, which are often complicated and clinically overlap with a broad number of movement disorders. The validity of exome sequencing as a routine diagnostic approach in the movement disorder clinic needs to be assessed. The main goal of this study was to explore the usefulness of an exome analysis for the diagnosis of a complicated form of spastic paraplegia. Whole‐exome sequencing was performed in two Spanish siblings with a neurodegenerative syndrome including upper and lower motor neuron, ocular and cerebellar signs. Exome sequencing revealed that both patients carry a novel homozygous nonsense mutation in exon 15 of the SPG11 gene (c.2678G>A; p.W893X), which was not found in 584 Spanish control chromosomes. After many years of follow‐up and multiple time‐consuming genetic testing, we were able to diagnose these patients by making use of whole‐exome sequencing, showing that this is a cost‐efficient diagnostic tool for the movement disorder specialist. 相似文献