全文获取类型
收费全文 | 221576篇 |
免费 | 20425篇 |
国内免费 | 15548篇 |
专业分类
耳鼻咽喉 | 1939篇 |
儿科学 | 2211篇 |
妇产科学 | 2984篇 |
基础医学 | 26716篇 |
口腔科学 | 3716篇 |
临床医学 | 30970篇 |
内科学 | 33115篇 |
皮肤病学 | 2242篇 |
神经病学 | 12481篇 |
特种医学 | 8284篇 |
外国民族医学 | 138篇 |
外科学 | 21904篇 |
综合类 | 35771篇 |
现状与发展 | 55篇 |
一般理论 | 19篇 |
预防医学 | 13251篇 |
眼科学 | 6747篇 |
药学 | 22915篇 |
195篇 | |
中国医学 | 12501篇 |
肿瘤学 | 19395篇 |
出版年
2024年 | 708篇 |
2023年 | 3589篇 |
2022年 | 9261篇 |
2021年 | 11674篇 |
2020年 | 8684篇 |
2019年 | 7656篇 |
2018年 | 8098篇 |
2017年 | 7136篇 |
2016年 | 6703篇 |
2015年 | 10318篇 |
2014年 | 12640篇 |
2013年 | 10774篇 |
2012年 | 16111篇 |
2011年 | 18052篇 |
2010年 | 10597篇 |
2009年 | 8251篇 |
2008年 | 11198篇 |
2007年 | 11150篇 |
2006年 | 11323篇 |
2005年 | 11390篇 |
2004年 | 7070篇 |
2003年 | 6662篇 |
2002年 | 5566篇 |
2001年 | 4966篇 |
2000年 | 5391篇 |
1999年 | 5746篇 |
1998年 | 3546篇 |
1997年 | 3515篇 |
1996年 | 2827篇 |
1995年 | 2620篇 |
1994年 | 2155篇 |
1993年 | 1384篇 |
1992年 | 1900篇 |
1991年 | 1600篇 |
1990年 | 1293篇 |
1989年 | 1093篇 |
1988年 | 1015篇 |
1987年 | 892篇 |
1986年 | 728篇 |
1985年 | 528篇 |
1984年 | 337篇 |
1983年 | 243篇 |
1982年 | 149篇 |
1981年 | 145篇 |
1980年 | 111篇 |
1979年 | 142篇 |
1978年 | 49篇 |
1977年 | 53篇 |
1975年 | 57篇 |
1974年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Patients with nonalcoholic fatty liver disease (NAFLD) have symptoms of a gut microbiota disorder with abnormal amino acid and glycolipid metabolism. This study was designed to analyze the characteristics of gut microbiota in patients with NAFLD, predict the gut microbiota phenotype, explore its role in the diagnosis of NAFLD, and establish its significance in disease progression.The characteristics of the gut microbiota in NAFLD patients (n = 28, 45.8 ± 14.2 years, male/female = 18/10) and healthy subjects (n = 20, 49.6 ± 4.8 years, male/female = 14/6) during March–May 2020 were analyzed using 16S rRNA sequencing technology and the phenotypes with large differences were predicted using the Tax4Fun method. The metabolites in the fecal samples of the patients were analyzed using mass spectrometry, and their correlation with different microorganisms was examined. The accuracy of the gut microbiota in diagnosing NAFLD was investigated by receiver operating characteristic curve analysis.We found that the microbial diversity and Bacteroides/Firmicutes (BF) ratio changed significantly (P < .05) in the feces of NAFLD patients. Phenotypic prediction showed that there were significant differences in the phenotypes of amino acid, glucose, and lipid metabolism of gut microbiota in the NAFLD group (P < .05). receiver operating characteristic curve analysis revealed that combination of Bacteroides and the BF ratio resulted in 88% and 100% sensitivity and specificity, respectively, when used for NAFLD diagnosis. Metabolomics and bioinformatics analysis revealed changes in the metabolism of nicotinate, nicotinamide, and pyrimidine; signaling pathways of calcium and oxytocin; pancreatic secretion with metabolites such as uracil, xanthine, and biliverdin; and enzymes such as xanthine dehydrogenase and xanthine oxidase (P < .05).Therefore, the phenotypic changes may be a potential marker for NAFLD and we considered that a combined analysis of Bacteroides and BF ratio had good diagnostic accuracy for NAFLD. 相似文献
992.
Background:The purpose of this study was to evaluate the clinical outcomes and complications of displaced proximal humeral fractures treated with proximal humeral internal locking system (PHILOS) plate fixation via a deltoid interfascicular (DI) vs a deltopectoral (DP) approach.Methods:This prospective case-control study was conducted with patients admitted to our hospital from May 2015 to June 2018 who suffered from unilateral displaced proximal humerus fractures. Patients were treated with PHILOS plate fixation via a DI (DI group) or DP approach (DP group). The clinical outcomes and complication data were collected for comparison between the 2 groups. The patients were followed up at 3, 6, and 12 months; and every 6 months thereafter. The patients’ functional recoveries were evaluated according to the normalized Constant-Murley score, range of motion of the shoulder (flexion, abduction, external/internal rotation) and disabilities of the arm, shoulder and hand score.Results:A total of 77 patients, followed for an average of 15 ± 2.2months (range, 12–21), were enrolled (36 in DI group and 41 in DP group) for final analysis. No significant differences in age, sex, affected side, fracture type, injury mechanism or time from injury to operation were found between the 2 groups (all P > .05). The incision length, intra-operative blood loss, and duration of operation in the DI group were significantly less than those in the DP group, respectively (all P < .05). The functional outcomes assessed by the normalized Constant-Murley score and range of motion of flexion and internal rotation in the DI group were superior to those in the DP group at 3 and 6months after the operation (P < .05); however, no significant differences were observed at the 12-month and subsequent follow-ups (all P > .05). There was no significant difference in the range of shoulder external rotation and abduction during the postoperative follow-ups (P > .05). At the last follow-up, the mean disabilities of the arm, shoulder, and hand score was 14.0 (6.6) points in the DI group and 14.4 (6.9) points in the DP group (P = .793). Complications occurred in 1 patient in the DI group and 8 patients in the DP group (P = .049).Conclusion:The current study demonstrates that DI approach is a safe and effective alternative for the treatment displaced proximal humerus fractures. The DI approach rather than DP approach was recommended when lateral and posterior exposure of the proximal humerus is required, especially when fixed with PHILOS plate. 相似文献
993.
Yushu Liu Yanyi Huang Guoheng Mo Tao Zhou Qian Hou Chaoqun Shi Jichun Yu Yunxia Lv 《Journal of clinical laboratory analysis》2022,36(7)
BackgroundA growing number of studies have found a close association between thyroid hormones and thyrotrophin (TSH), and they also have prognostic significance in some cancer types; this study aimed to investigate the prognostic value of free triiodothyronine (fT3), free thyroxine (fT4), fT3/fT4, TSH, and their combination in patients with papillary thyroid carcinoma (PTC).MethodsThis study retrospectively analyzed the relevant data of 726 newly diagnosed PTC patients. Both univariate and multivariate analyses were used to predict the recurrence rate, and a risk score was established. In addition, with the use of a random survival forest, a random forest (RF) score was constructed. After calculating the area under the curve (AUC), the diagnostic efficacy of risk score, RF score, and four indicators was compared.ResultsfT3, fT4, fT3/fT4, and TSH were strongly associated with some invasive clinicopathological features and postoperative recurrence. Patients with high expression of fT4 and TSH have a high risk of recurrence. By contrast, patients with high expression of fT3 and fT3/fT4 have a low risk of recurrence. At the same time, the combined use of various indicators is more helpful for establishing an accurate diagnosis. By comparison, we found that the RF score was better than the risk score in terms of predicting the recurrence of PTC.ConclusionThe diagnostic accuracy of a combination of fT3, fT4, fT3/fT4, and TSH can help improve our clinical estimate of the risk of recurrent PTC, thus allowing the development of a more effective treatment plan for patients. 相似文献
994.
BackgroundHepatocellular carcinoma (HCC) is the sixth most common cancer and the fourth leading cause of cancer‐related death in the world. A number of challenges remain for the early detection and effective treatment of HCC. In recent years, microbiota have been proven to be associated with the development of HCC. Many studies have explored the pathogenesis, diagnostic marker, and therapeutic target potential of microbiota in hepatocellular carcinoma. Therefore, we aimed to introduce the research methods and achievements of gut microbiota in hepatocellular carcinoma and discuss the value of gut microbiota in the pathogenesis, diagnosis, and treatment of hepatocellular carcinoma.MethodsKeywords are used to search relevant articles which were mainly published from 2010 to 2021, and we further selected targeted articles and read the full text.ResultsGut microbiota involved in promoting the formation and development of hepatocellular carcinoma, and differential gut microbiota and microbial metabolites have the potential to be the biomarkers of hepatocellular carcinoma. Purposefully regulated gut microbiota can improve the prognosis of patients, which is expected to be used in hepatocellular carcinoma.ConclusionThe study of gut microbiota in hepatocellular carcinoma is definitely worthy of study. In‐depth and elaborate research design is crucial for the study of the mechanism of gut microbiota involved in hepatocellular carcinoma, which can provide new directions and targets for the diagnosis, treatment, and prognosis of hepatocellular carcinoma. 相似文献
995.
Xuan Han WuHu Zhang HeLi Gao TianJiao Li HuaXiang Xu Hao Li PengCheng Li Xu Wang XianJun Yu WenQuan Wang Liang Liu 《Journal of clinical laboratory analysis》2022,36(7)
BackgroundThe selective pressure imposed by chemotherapy creates a barrier to tumor eradication and an opportunity for metastasis and recurrence. As a newly discovered stemness marker of pancreatic ductal adenocarcinoma (PDAC), the impact of CD9 on tumor progression and patient''s prognosis remain controversial.MethodsA total of 179 and 211 PDAC patients who underwent surgical resection with or without neoadjuvant chemotherapy, respectively, were recruited for immunohistochemical analyses of CD9 expression in both tumor and stromal areas prior to statistical analyses to determine the prognostic impact and predictive accuracy of CD9.ResultsThe relationship between CD9 and prognostic indicators was not significant in the non‐neoadjuvant group. Nevertheless, CD9 expression in both tumor (T‐CD9) and stromal areas (S‐CD9) was significantly correlated with the clinicopathological features in the neoadjuvant group. High levels of T‐CD9 were significantly associated with worse OS (p = 0.005) and RFS (p = 0.007), while positive S‐CD9 showed the opposite results (OS: p = 0.024; RFS: p = 0.008). Cox regression analyses identified CD9 in both areas as an independent prognostic factor. The T&S‐CD9 risk‐level system was used to stratify patients with different survival levels. The combination of T&S‐CD9 risk level and TNM stage were accurate predictors of OS (C‐index: 0.676; AIC: 512.51) and RFS (C‐index: 0.680; AIC: 519.53). The calibration curve of the nomogram composed of the combined parameters showed excellent predictive consistency for 1‐year RFS. These results were verified using a validation cohort.ConclusionNeoadjuvant chemotherapy endows CD9 with a significant prognostic value that differs between tumor and stromal areas in patients with pancreatic cancer. 相似文献
996.
Daoqin Liu Chengcheng Yang Ru Zhou Hongjing Zhao Tingwei Si Chunsheng Liu Qiwen Wu 《Journal of clinical laboratory analysis》2022,36(7)
ObjectivesThis study aimed to investigate the effect of hemoglobin (Hb) fluctuation after dialysis on the prognosis of cardiovascular‐related and all‐cause deaths in peritoneal dialysis (PD).MethodsAccording to the Hb fluctuation, patients were divided into low fluctuation group, moderate fluctuation group, and high fluctuation group, and then, the effects of Hb fluctuation after dialysis on the prognosis of cardiovascular‐related and all‐cause death in PD were analyzed by regression analysis.ResultsA total of 232 patients were selected in this study. Compared with the low Hb fluctuation group, the moderate and high fluctuation groups had lower body mass index (BMI), estimated glomerular filtration rate (eGFR), and baseline Hb, and the moderate fluctuation group had less erythropoietin (EPO) and dialysis dose. Compared with survivors, patients with cardiovascular‐related and all‐cause deaths had lower mean Hb and Hb fluctuation (all p < 0.05). Cox regression analysis showed that before and after adjusting for confounding factors, Hb fluctuation was still independently correlated with cardiovascular prognosis, and higher Hb fluctuation was still a protective factor for cardiovascular‐related death in the Hb‐substandard group, but there was no significant correlation between Hb fluctuation and all‐cause death. Multivariate linear regression analysis revealed that Hb fluctuation was positively correlated with Kt/V and EPO dosage, but negatively correlated with the baseline Hb.ConclusionHigh Hb fluctuation was a protective factor for cardiovascular‐related death in PD with substandard Hb. Compared with Hb fluctuation, correction of anemia timely and making Hb reaches the standard level had a greater impact on reducing cardiovascular‐related death in PD. 相似文献
997.
Lieqiang Liao Ruidong Liu Shuwen Hu Wenting Jiang Yali Chen Jinlian Zhong Xinjian Jia Huijin Liu Xuzhong Luo 《RSC advances》2022,12(31):20218
In this paper, we report self-assembled sonogels formed from 1,4-naphthalenedicarbonyldinicotinic acid hydrazide (NDC-NN3) in some liquids including ethanol, tetrahydrofuran (THF), 1,4-dioxane, n-propanol, n-butanol and n-pentanol. When the clear solution of NDC-NN3 in the selected liquids mentioned above at a suitable concentration was irradiated with ultrasound waves at room temperature, a sonogel was formed. Upon heating, the sonogel dissolved gradually and finally became a clear solution again. Upon cooling the hot solution to room temperature, the solution state did not change even after standing for a few days. Nevertheless, if the solution underwent sonication for a certain time, a stable gel was obtained again. The critical gelation concentrations (CGCs) of NDC-NN3 in ethanol, THF, 1,4-dioxane, n-propanol, n-butanol and n-pentanol are 10, 8, 6, 8, 6 and 8 mg mL−1, respectively. The obtained sonogels display excellent mechanical properties. The crystal structure of NDC-NN3 suggests that the naphthalene ring, hydrazide group and the position of N in the pyridine ring mediate the self-assembly process. Upon sonication, the formation of suitable π–π stacking and intermolecular hydrogen bonding drives the gelator molecules to self-assemble into fibers, spheres and micro-burdock-shaped balls in various solvents, which ultimately confine the liquids.Ultrasound-induced gelation of a novel type of gelator, 1,4-naphthalenedicarbonyl- dinicotinic acid hydrazide, is reported. The gelator self-assembled into various architectures in different solvents. 相似文献
998.
Xiurong Zhu Lousia J. Hope-Weeks Yi Yu Jvjun Yuan Xianke Zhang Huajun Yu Jiajun Liu Xiaofen Li Xianghua Zeng 《RSC advances》2022,12(31):20191
By using glycidol as a catalyst, high porosity, low-density resorcinol (R) and formaldehyde (F) aerogels and carbon aerogels (CAs) were synthesized via a sol-gel method. The effect of glycidol and water on the color, density, morphology, textual characteristics and adsorption properties of the resultant RF aerogels and CAs were investigated in detail. The results revealed that the properties of RF aerogels and CAs can be controlled by adjusting the amount of glycidol and water. The resultant RF aerogels and CAs were porous materials, the minimum densities of RF aerogels and CAs were 96 and 110 mg cm−3 respectively while the maximum specific surface areas of RF aerogels and CAs were 290 and 597 m2 g−1. The maximum adsorption capacity of CAs was about 125 mg g−1 on Rhodamine B, which was higher than that of some reported CAs catalyzed by base and acid catalysts. The sol-gel mechanisms of RF aerogels and CAs can be attributed to the opening of the epoxy group of glycidol in the mixture of R and F.The sol-gel mechanism of glycidol-catalyzed RF aerogels is the opening of the epoxy ring rather than the preservation the of epoxy ring. 相似文献
999.
1000.
Longyu Wang Haoyang Li Xiao Wang Xiaofeng Liu Weiqing Ma Guangji Zhou Qiaochu Liang Huixia Lan 《RSC advances》2022,12(32):20983
In this study, the effect of pH shock during the treatment of sulfate-containing organic wastewater was investigated using an anaerobic fermentation system reinforced with graphene oxide (GO)/iron series systems. The results show that the anaerobic system with the GO/iron series systems exhibited enhanced resistance to pH shock. Among them, the GO/Fe0 system had the strongest resistance to pH shock, the systems of GO/Fe3O4 and GO/Fe2O3 followed close behind, while the blank system performed the worst. After pH shock, the CODCr removal rate, SO42− removal rate, and gas production of the GO/Fe0 group were significantly improved compared with those of the control group by 51.0%, 65.3%, and 34.6%, respectively, while the accumulation of propionic acid was the lowest. Further, detailed microbial characterization revealed that the introduction of the GO/iron series systems was beneficial to the formation of more stable anaerobic co-metabolic flora in the system, and the relative abundance of Geobacter, Clostridium, Desulfobulbus and Desulfovibrio increased after acidic and alkaline shock.In this paper, we studied the pH shock resistance mechanism of GO/iron series from the perspectives of the treatment effect, changes in effluent pH and VFA, and microbial co-metabolic stability, providing a reference for the practical application. 相似文献