全文获取类型
收费全文 | 55961篇 |
免费 | 5246篇 |
国内免费 | 3540篇 |
专业分类
耳鼻咽喉 | 543篇 |
儿科学 | 671篇 |
妇产科学 | 468篇 |
基础医学 | 6527篇 |
口腔科学 | 859篇 |
临床医学 | 6736篇 |
内科学 | 9072篇 |
皮肤病学 | 689篇 |
神经病学 | 3127篇 |
特种医学 | 2574篇 |
外国民族医学 | 19篇 |
外科学 | 5904篇 |
综合类 | 8991篇 |
现状与发展 | 15篇 |
一般理论 | 7篇 |
预防医学 | 3559篇 |
眼科学 | 1367篇 |
药学 | 5951篇 |
52篇 | |
中国医学 | 2891篇 |
肿瘤学 | 4725篇 |
出版年
2024年 | 176篇 |
2023年 | 792篇 |
2022年 | 2051篇 |
2021年 | 2773篇 |
2020年 | 2043篇 |
2019年 | 1807篇 |
2018年 | 1878篇 |
2017年 | 1726篇 |
2016年 | 1855篇 |
2015年 | 2678篇 |
2014年 | 3189篇 |
2013年 | 3155篇 |
2012年 | 4493篇 |
2011年 | 4772篇 |
2010年 | 3438篇 |
2009年 | 2639篇 |
2008年 | 3188篇 |
2007年 | 3164篇 |
2006年 | 2889篇 |
2005年 | 2827篇 |
2004年 | 2049篇 |
2003年 | 2132篇 |
2002年 | 1800篇 |
2001年 | 1319篇 |
2000年 | 1022篇 |
1999年 | 974篇 |
1998年 | 582篇 |
1997年 | 568篇 |
1996年 | 377篇 |
1995年 | 438篇 |
1994年 | 310篇 |
1993年 | 190篇 |
1992年 | 277篇 |
1991年 | 200篇 |
1990年 | 168篇 |
1989年 | 174篇 |
1988年 | 117篇 |
1987年 | 125篇 |
1986年 | 119篇 |
1985年 | 62篇 |
1984年 | 41篇 |
1983年 | 21篇 |
1982年 | 25篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 15篇 |
1974年 | 8篇 |
1973年 | 13篇 |
1972年 | 9篇 |
1969年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
Yun-Young Choi Jee Young Lee Su-Hyun Yang Tae-Geol Lee Da-Yoon Oh Dong Woo Kim Soo-Jin Lee Yoon Jae Lee In-Hyuk Ha 《Medicine》2022,101(45)
This study aimed to investigate the long-term clinical efficacy of and satisfaction with integrative Korean medicine (KM) treatment in patients with shoulder osteoarthritis (SOA). We conducted a prospective observational study of patients with SOA. Patients aged 19 years and older who underwent inpatient treatment for more than 1 week were eligible for enrollment in the study. The primary evaluation index was the numeric rating scale for shoulder pain. Sub-evaluation indices included the Shoulder Pain and Disability Index for shoulder function, EuroQol-5-dimension score for overall quality of life, and Patient Global Impression of Change. Outcome measures were assessed at admission, discharge, and follow-up. For the follow-up questionnaire survey, the following information was collected: current status, surgery after discharge, reasons for finding integrative KM treatment satisfactory/unsatisfactory, and quality of life after discharge. In total, 186 patients were enrolled in the primary analysis, and 103 patients completed the follow-up survey. The mean number of days of follow-up was 1019 ± 439. Compared with the baseline, the mean differences in the numeric rating scale and Shoulder Pain and Disability Index were 3.05 ± 0.34 and 36.06 ± 5.53, respectively. Regarding the Patient Global Impression of Change, 89 out of 103 (86.4%) patients chose “minimally improved” or better. Furthermore, the EuroQol-5-dimension score also increased, showing an improvement of health-related quality of life after treatment. Integrative KM treatment is a potential option for reducing pain severity and improving function and health-related quality of life in patients with SOA. Prospective randomized studies would support this finding for the next step. 相似文献
943.
944.
945.
Polymer-derived ceramic (PDC) coatings of considerable thickness can offer promising protection for metallic and superalloy substrates against oxidation and corrosion, yet the preparation remains challenging. Here, a SiOC/Al2O3/YSZ coating was prepared on a nickel alloy with a spraying method using Al2O3 and yttria-stabilized zirconia (YSZ) as passive fillers. The thickness can reach up to 97 μm with the optimal mass fraction and particle sizes of the passive fillers. A small or isolated SiOC phase is formed in the coating, which can effectively alleviate the shrinkage and cracking during the pyrolysis. The SiOC/Al2O3/YSZ coating exhibits low thermal conductivity and high bonding strength with the substrate. Moreover, the coating shows good thermal shock resistance between 800 °C-room temperature cycles and oxidation resistance at 1000 °C for 36 h. This work provides an effective guide for the design of thick PDC coatings to further promote their application in the thermal protective field. 相似文献
946.
Recycled aggregate concrete (RAC) is a sort of green, low carbon, environmental protection building material, its application is of great significance to the low carbonization of the construction industry. The performance and strength of RAC are much lower than natural aggregate concrete (NAC), which are the key factors restricting its application. Class F fly ash is a cementitious material that is considered environmentally hazardous. In this paper, appropriate water-binder (w/b) ratios were found through a mortar expansion test at first. The compressive strength of recycled mortar incorporated with class F fly ash was further studied. On this basis, the mechanical properties of nine groups of fully recycled aggregate concrete (FRAC) with a w/b ratio of 0.3, 0.35, and 0.4, and fly ash replacement ratios of 0, 20%, and 40%, were studied. The influence of the w/b ratio and fly ash replacement ratio on mechanical properties was analyzed and compared with previous research results. In addition, the conversion formulas between the splitting tensile strength, flexural strength, and compressive strength of FRAC were fitted and established. The research results have a certain guiding significance for the mixture design of FRAC and further application of class F fly ash. 相似文献
947.
Xiaoyang Dong Jinxing Wang Zichuan Wang Xiyu Wang Cong Dang Zhicheng Wan Yi Zou Jingfeng Wang Fusheng Pan 《Materials》2022,15(22)
Designing new materials for vibration and noise reduction that are lightweight is of great significance for industrial development. Magnesium (Mg) alloy is considered one of the best damping metal structural materials because of its low density, high specific strength, good energy storage characteristics and rich resources. Solution atoms have an important effect on the damping capacities of Mg alloys, but the relevant laws have not been completely clarified. In this work, two kinds of alloying elements (Ga and Er) with various atomic sizes were selected to study the metallographic structure and damping capacities of binary Mg-X (X = Ga and Er) alloys in the as-cast and solid solution states, respectively. Solution treatment can improve the damping capacities of binary Mg-X (X = Ga and Er) alloys, and the damping mechanisms of the two solid solution alloys are consistent with the G-L damping mechanism. The influence of alloy elements with different atomic sizes on damping capacities is also different. This influence is due to the various radii of solute atoms and Mg atoms which can result in different degrees of lattice distortion. This work provides a research basis for development and design of high-performance damping Mg alloy materials. 相似文献
948.
Dong Cui Xiaohan Shi Wenya Liu Keren Zheng Guangji Yin Jing Wang Guantong Han Yi Wan Junsong Wang Wenting Li 《Materials》2022,15(22)
Investigation of the neutralizing behavior of concrete is essential, as it can help reveal the durability properties of concrete structures. In this paper, anthocyanin extracted from February orchid (F. orchid) petals was used to characterize the neutralized (carbonated, leached, and sulfate-attacked) regions of cement-based materials. The durability of F. orchid indicator was evaluated through comparison between discoloring behaviors of fresh and aged F. orchid indicators, and the capability of the new indicator in neutralization characterization was then verified by combining indicator (phenolphthalein, malachite green, indigo carmine, or thymolphthalein) spray, X-ray computed tomography (CT), and the X-ray attenuation method (XRAM). The result in the present study showed that, with a lower color intensity as compared to phenolphthalein/thymolphthalein, F. orchid indicator was less preferable in studying carbonation but a better choice in characterizing leaching and sulfate attack of cement-based materials. In addition, a sharp carbonation front was revealed in the present study, suggesting that the carbonation process in this study was controlled mainly by diffusion. For leaching and sulfate attack, the broader fronts revealed suggested that both processes were co-controlled by diffusion and reaction. The current work serves as a ‘leap’ toward the application of natural pigments in analyzing the durability of concrete structures. 相似文献
949.
Zhen Dong Yanpeng Chen Xinggang Wang Lingfeng Kong Lianguo Wang Xinning Li Fenjin Sun Ke Ding Hanqi Wu Shanshan Chen Mengyuan Zhang 《Materials》2022,15(23)
In this study, thermophysical and mechanical tests were conducted on sandstone samples from room temperature to 1000 °C. Based on the test results, the thermophysical properties (such as specific heat capacity, thermal conductivity, and thermal expansion coefficient) of sandstone after high-temperature treatment and the variations of mechanical properties (including peak strength, peak strain, elastic modulus, and whole stress-strain curve) with temperature were analyzed. Indeed, the deterioration law of sandstone after high-temperature treatment was also explored with the aid of a scanning electron microscope (SEM). The results show that with the increase in temperature, the specific heat capacity and thermal expansion coefficient of sandstone samples after high-temperature treatment increase first and then decrease, while the thermal conductivity gradually decreases. The range from room temperature to 1000 °C witnesses the following changes: As temperature rises, the peak strength of sandstone rises initially and falls subsequently; the elastic modulus drops; the peak strain increases at an accelerated rate. Temperature change has a significant effect on the deterioration rules of sandstone, and the increase in temperature contributes to the transition in the failure mode of sandstone from brittle failure to ductile failure. The experimental study on the thermophysical and mechanical properties of sandstone under the action of high temperature and overburden pressure has a guiding significance for the site selection and safety evaluation of UCG projects. 相似文献
950.
Marine fouling on concrete has become one of the severest problems that damage the surface and even cause internal corrosion of marine concrete. Dissimilarly to the previous abuse of toxic antifoulants, developing hydrophobic waterborne antifouling materials could be regarded as one of the most environment-friendly and potential directions to protect marine concrete. However, the insufficient hydrophobicity, antifouling, and mechanical properties limit their application. Herein, we reported a series of hybrid coatings combining hyperbranched polyglycerol (HPG) decorated waterborne fluoro silicone polyurethane (H) and HPG-grafted graphene oxide (G-HPG) that improve the hydrophobicity, antifouling, and mechanical properties. The hybrid materials were modified by the hyperbranched polyglycerol synthesized based on the anionic-ring-opening reaction between glycerol and ethylene glycol or polyethylene glycol. Remarkably, the hydrophobicity (115.19°) and antifouling properties (BSA absorption of 2.33 μg/cm2 and P. tricornutum attachment of 1.289 × 104 CFU/cm2) of the materials could be developed by the modification of HPG with higher generation numbers and backbone molecular weights. Moreover, the mechanical properties negligibly decreased (tensile strength decreased from 11.29 MPa to 10.49 MPa, same pencil hardness and adhesion grade as H of 2H and grade 2). The results revealed that the HPG of higher generation numbers and backbone molecular weights could benefit materials with enhanced antifouling properties and hydrophobicity. The method of hyperbranched modification can be regarded as potentially effective in developing the durability and antifouling properties of marine antifouling materials. 相似文献