全文获取类型
收费全文 | 131413篇 |
免费 | 7537篇 |
国内免费 | 1117篇 |
专业分类
耳鼻咽喉 | 2048篇 |
儿科学 | 2007篇 |
妇产科学 | 1946篇 |
基础医学 | 20918篇 |
口腔科学 | 3156篇 |
临床医学 | 12263篇 |
内科学 | 23402篇 |
皮肤病学 | 4195篇 |
神经病学 | 10547篇 |
特种医学 | 7505篇 |
外科学 | 17199篇 |
综合类 | 578篇 |
现状与发展 | 3篇 |
一般理论 | 27篇 |
预防医学 | 7002篇 |
眼科学 | 3352篇 |
药学 | 11883篇 |
中国医学 | 1512篇 |
肿瘤学 | 10524篇 |
出版年
2023年 | 927篇 |
2022年 | 2811篇 |
2021年 | 4529篇 |
2020年 | 2190篇 |
2019年 | 3054篇 |
2018年 | 3822篇 |
2017年 | 3119篇 |
2016年 | 4067篇 |
2015年 | 5668篇 |
2014年 | 6677篇 |
2013年 | 7846篇 |
2012年 | 11674篇 |
2011年 | 11170篇 |
2010年 | 6445篇 |
2009年 | 5505篇 |
2008年 | 7798篇 |
2007年 | 7411篇 |
2006年 | 6682篇 |
2005年 | 6207篇 |
2004年 | 5374篇 |
2003年 | 4699篇 |
2002年 | 4030篇 |
2001年 | 3083篇 |
2000年 | 2828篇 |
1999年 | 2163篇 |
1998年 | 933篇 |
1997年 | 685篇 |
1996年 | 522篇 |
1995年 | 464篇 |
1994年 | 405篇 |
1993年 | 342篇 |
1992年 | 765篇 |
1991年 | 709篇 |
1990年 | 650篇 |
1989年 | 571篇 |
1988年 | 482篇 |
1987年 | 475篇 |
1986年 | 346篇 |
1985年 | 387篇 |
1984年 | 272篇 |
1983年 | 197篇 |
1982年 | 135篇 |
1981年 | 178篇 |
1980年 | 131篇 |
1979年 | 228篇 |
1978年 | 166篇 |
1976年 | 134篇 |
1975年 | 124篇 |
1974年 | 141篇 |
1973年 | 121篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
The hepatoprotective activity of lactic acid bacteria (Lactobacillus brevis HY7401, Lactobacillus acidophilus CSG and Bifidobacterium longum HY8001), which inhibited beta-glucuronidase productivity of intestinal microflora, on t-BHP- or CCl4-induced hepatotoxicity of mice were evaluated. These oral administration of lactic acid bacteria lowered beta-glucuronidase production of intestinal microflora as well as Escherichia coli HGU-3. When lactic acid bacteria at a dose of 0.5 or 2 g (wet weight)/kg was orally administered on CCl4-induced liver injury in mice, these bacteria significantly inhibited the increase of plasma alanine transferase and aspartate transferase activities by 17-57% and 57-66% of the CCl4 control group, respectively. These lactic acid bacteria also showed the potent hepatoprotective effect against t-BHP-induced liver injury in mice. The inhibitory effects of these lactic acid bacteria were more potent than that of dimethyl diphenyl bicarboxylate (DDB), which have been used as a commercial hepatoprotective agent. Among these lactic acid bacteria, L. acidophilus CSG exhibited the most potent hepatoprotective effect. Based on these findings, we insist that an inhibitor of beta-glucuronidase production in intestine, such as lactic acid bacteria, may be hepatoprotective. 相似文献
992.
Yusuf Osmanlolu Drew Parker Jacob A. Alappatt James J. Gugger Ramon R. DiazArrastia John Whyte Junghoon J. Kim Ragini Verma 《Human brain mapping》2022,43(13):3944
Traumatic brain injury (TBI) is a major public health problem. Caused by external mechanical forces, a major characteristic of TBI is the shearing of axons across the white matter, which causes structural connectivity disruptions between brain regions. This diffuse injury leads to cognitive deficits, frequently requiring rehabilitation. Heterogeneity is another characteristic of TBI as severity and cognitive sequelae of the disease have a wide variation across patients, posing a big challenge for treatment. Thus, measures assessing network‐wide structural connectivity disruptions in TBI are necessary to quantify injury burden of individuals, which would help in achieving personalized treatment, patient monitoring, and rehabilitation planning. Despite TBI being a disconnectivity syndrome, connectomic assessment of structural disconnectivity has been relatively limited. In this study, we propose a novel connectomic measure that we call network normality score (NNS) to capture the integrity of structural connectivity in TBI patients by leveraging two major characteristics of the disease: diffuseness of axonal injury and heterogeneity of the disease. Over a longitudinal cohort of moderate‐to‐severe TBI patients, we demonstrate that structural network topology of patients is more heterogeneous and significantly different than that of healthy controls at 3 months postinjury, where dissimilarity further increases up to 12 months. We also show that NNS captures injury burden as quantified by posttraumatic amnesia and that alterations in the structural brain network is not related to cognitive recovery. Finally, we compare NNS to major graph theory measures used in TBI literature and demonstrate the superiority of NNS in characterizing the disease. 相似文献
993.
C型钠尿肽抑制大鼠胃窦环行肌自发性收缩活动 总被引:3,自引:0,他引:3
Guo HS Cui X Cui YG Kim SZ Cho KW Li ZL Xu WX 《Acta pharmacologica Sinica》2003,24(10):1021-1026,1062
目的:研究钠尿肽对胃动力的作用及其可能的机制.方法:用四道记录仪记录胃窦环行肌条的自发性收缩活动;利用放射免疫技术测定cGMP的产生量;利用放射自显影技术分析钠尿肽受体在胃内的分布情况.结果:钠尿肽受体在大鼠胃的不同部位均有分布,但在胃窦部最多。ANP、BNP和CNP均能抑制胃窦环行肌条的自发性收缩,其中,CNP的作用尤为明显并呈剂量依赖关系.CNP的这种抑制性作用被鸟苷酸环化酶抑制剂LY83583所削弱,而用cGMF敏感的磷酸酯酶抑制剂zaparinist预处理时CNP的抑制作用明显增加.CNP明显提高胃窦环行肌cGMP的浓度.用非选择性钾通道阻断剂TEA预处理后发现CNP对胃窦环行肌自发性收缩活动的抑制作用明显减弱.结论:钠尿肽受体在大鼠的胃窦分布最多.CNP明显抑制大鼠胃窦环行肌的自发性收缩活动.CNP对大鼠胃窦环行肌自发性收缩活动的抑制效应是通过cGMP途径实现的.钾通道也参与CNP对大鼠胃窦平滑肌的舒张过程。 相似文献
994.
Meijie Tian Adam T. Cheuk Jun S. Wei Abdalla Abdelmaksoud Hsien-Chao Chou David Milewski Michael C. Kelly Young K. Song Christopher M. Dower Nan Li Haiying Qin Yong Yean Kim Jerry T. Wu Xinyu Wen Mehdi Benzaoui Katherine E. Masih Xiaolin Wu Zhongmei Zhang Sherif Badr Naomi Taylor Brad St. Croix Mitchell Ho Javed Khan 《The Journal of clinical investigation》2022,132(16)
995.
To enhance the formability of magnesium alloys, inhibition of basal texture development by the particle-stimulated nucleation (PSN) effect has attracted significant interest. However, its contribution to texture development is not easily observed due to the separation of texture from the conventional deformation behavior. This study aims to separate the Ca texture from the deformation behavior of AZX611 alloy and quantify it using scanning electron microscopy with electron backscatter diffraction (SEM-EBSD). Since Ca in the AZ61 magnesium alloy precipitated as Al2Ca, the hot-rolled magnesium alloys AZ31, AZ61, and AZX611 were used. High temperature compression was conducted at 723 K, the strain rate 0.05/s and 0.005/s and the true strain up to −1.0. Dynamic recrystallization was observed in each specimen and the Ca-free alloys showed dislocation glide at high strain rates and solute drag at low strain rates. When the dislocation glide dominated, basal texture was strengthened. In contrast, solute drag caused non-basal texture development. Precipitation hardening caused AZ61 to have higher flow stress than those of the Ca-free alloys by the PSN effect; its texture was observed separately because the PSN grain growth around the precipitation and orientation was specific, similar to the one developed at the solute atom drag. 相似文献
996.
Concrete structures are constructed in various geographical environments and climates, and frequently fail to fulfill their original functions over time due to issues such as aging and damage. Research on concrete structure repair materials is being conducted to solve these problems. This study evaluated the durability of a repair material composed of ultra-rapid hardening cement, styrene–butadiene (SB) latex polymer, and wollastonite mineral fiber. The performance targets were as follows: compressive strength of 20 MPa at 1 day of age and 45 MPa at 28 days of age, chloride ion charge passed of less than 1000 Coulombs, carbonation depth of 20 mm or less, and resistance to repeated freezing and thawing (relative dynamic modulus of elasticity) of 80% or more. The ultra-rapid hardening cement:silica sand ratio of 1:1.5 was the experimental variable, and the unit weight of each material in the mix proportion was determined to satisfy the flow requirement of 200 ± 5 mm. This flow ensured sufficient fluidity for spraying, which is the most widely used method for applying repair material. Wollastonite mineral fiber and SB latex polymer were added at 3% and 5% of the unit weight of the binder, respectively. The mechanical property of the repair material was evaluated through compressive strength, and durability was evaluated through chloride ion penetration, alkali resistance, resistance to carbonation, water absorption, and repeated freezing and thawing tests. The compressive strength satisfied both target values, regardless of the addition of SB latex polymer and wollastonite mineral fiber. The chloride ion penetration test, which was used as an indicator of durability, showed that mixtures without SB latex and wollastonite mineral fiber were not satisfied the target charge passed of 1000 Coulombs, while mixtures with latex and mineral fiber reached the target value. Notably, the co-addition of latex and wollastonite fiber showed the highest resistance to chloride ion penetration, alkali ion, carbonation, repeated freezing and thawing, and the least absorption. The results confirmed that the durability of the repair material based on ultra-rapid hardening cement was most effectively improved by the co-addition of SB latex polymer and wollastonite mineral fiber. 相似文献
997.
Yeon Soo Kim Jae Won Choi Ju-Kyeong Park Hyun Jung Kim 《Acta oto-laryngologica》2015,135(12):1311-1318
Conclusion: The results of the present investigation suggest that modification of HA could improve efficiency and durability in augmentation laryngoplasty. Objectives: Injection laryngoplasty (IL) is one of the most suitable options for treatment of glottic insufficiency, which is caused by vocal fold (VF) paralysis, atrophy, or scarring. Hyaluronic acid (HA) is a widely used material for VF injection. This study was intended to evaluate the durability and efficiency of HA of different particle sizes for VF augmentation. Methods: Three types of HA, Restylane®, monophasic low-viscosity, and unequal particle-sized middle-viscosity HA were injected into the left VF of three groups with eight rabbits each. Results: After 6 and 10 weeks, the injected site was evaluated endoscopically, histologically, radiologically, and functionally. None of the 24 rabbits showed any signs of respiratory distress. Computed tomography (CT) images and endoscopic evaluation revealed sufficient augmented volume of the injected VF in all treated groups 6 weeks after the injection. Histological data at week 10 showed that unequal particle-sized HA did not migrate from its original injection site, while other HAs migrated to the periphery of the arytenoid cartilage. Videokymographic analysis showed more favorable vibrations of unequal particle-sized HA injected VF mucosa 10 weeks post-injection, compared to the other treatment groups. 相似文献
998.
A previous animal study demonstrated that the administration of Omija extract and soybean mixture (OSM) improved glycemic control in the type 2 diabetes model. In this study, we conducted a 12-week, randomized, double-blinded, and placebo-controlled clinical trial to determine the effects of OSM in humans with hyperglycemia. Participants with fasting plasma concentrations of 100–140 mg/dL were enrolled (n = 80) and administered either OSM or placebo products for 12 weeks. The outcomes included measurements of efficacy (fasting plasma glucose (FPG), postprandial glucose (PPG), fasting plasma insulin (FPI), postprandial insulin (PPI), hemoglobin A1c (HbA1c), C-peptide, fructosamine, and lipid parameters) and safety at baseline and at 12 weeks. After the intervention, the OSM group showed significantly decreased levels of FPG, PPG (30, 60 min), PPI (60 min), insulin area under the curve (AUC), fructosamine, and low-density-lipoprotein (LDL) cholesterol compared to the placebo group. No clinically significant changes in any safety parameter were observed. Therefore, it is hypothesized that OSM supplementation is an effective and safe functional food supplement for humans with hyperglycemia. 相似文献
999.
1000.