首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   256556篇
  免费   16183篇
  国内免费   7598篇
耳鼻咽喉   2950篇
儿科学   8903篇
妇产科学   3370篇
基础医学   19961篇
口腔科学   4663篇
临床医学   29825篇
内科学   43914篇
皮肤病学   3406篇
神经病学   12799篇
特种医学   14116篇
外国民族医学   28篇
外科学   35258篇
综合类   26532篇
现状与发展   36篇
一般理论   5篇
预防医学   18598篇
眼科学   5789篇
药学   27667篇
  127篇
中国医学   9648篇
肿瘤学   12742篇
  2023年   2355篇
  2022年   4480篇
  2021年   10442篇
  2020年   6839篇
  2019年   12680篇
  2018年   7465篇
  2017年   6675篇
  2016年   8539篇
  2015年   11380篇
  2014年   20442篇
  2013年   18302篇
  2012年   21422篇
  2011年   18313篇
  2010年   16619篇
  2009年   15806篇
  2008年   14337篇
  2007年   14310篇
  2006年   12131篇
  2005年   8207篇
  2004年   4483篇
  2003年   3914篇
  2002年   3096篇
  2001年   2584篇
  2000年   2325篇
  1999年   1538篇
  1998年   1761篇
  1997年   1631篇
  1996年   1371篇
  1995年   1505篇
  1994年   1435篇
  1993年   1094篇
  1992年   1279篇
  1991年   1140篇
  1990年   1162篇
  1989年   1108篇
  1988年   1024篇
  1987年   923篇
  1986年   738篇
  1985年   1846篇
  1984年   2043篇
  1983年   1512篇
  1982年   1562篇
  1981年   1511篇
  1980年   1306篇
  1979年   1132篇
  1978年   891篇
  1977年   836篇
  1976年   740篇
  1975年   506篇
  1974年   520篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
目的探讨解偶联蛋白1(UCP1)基因多态性与2型糖尿病(T2DM)心脑血管并发症的相关性。方法选取2019年7月—2020年7月住院治疗的T2DM 440例,根据有无心脑血管并发症分为观察组(T2DM合并心脑血管并发症)221例和对照组(单纯T2DM)219例。比较两组一般资料,UCP1在rs45539933、rs10011540及rs1800592位点的基因型分布与等位基因频率;通过多因素Logistic回归分析评估T2DM发生心脑血管事件的危险因素。结果观察组病程长于对照组,糖化血红蛋白水平高于对照组,而血清高密度脂蛋白胆固醇水平低于对照组(P<0.01)。观察组C/C基因型分布及C碱基频率均高于对照组(P<0.05)。C/C基因型是T2DM患者发生心脑血管并发症的危险因素(P<0.05)。结论UCP1基因多态性与T2DM心脑血管并发症的发生显著相关。  相似文献   
92.
93.
刘玲 《中国校医》2022,36(9):701-704
目的 探究采用高强度聚焦超声(HIFU)联合甲氨蝶呤(MTX)在瘢痕子宫妊娠行宫腔镜微创清宫术中的应用效果。方法 选择2018年5月—2019年5月在本院接受宫腔镜治疗的108例瘢痕子宫妊娠患者,依据随机数字表法分为研究组与对照组,每组各54例。对照组使用HIFU预处理,研究组则使用HIFU联合MTX的方式预处理,处理后两组均行宫腔镜辅助微创清宫术。通过随访分析比较两组的治疗效果及妊娠结局。结果 研究组术后7 d血清β-HCG水平为(28 598.38±2 176.52)U/L,低于对照组的(32 423.13±2 734.65)U/L,差异有统计学意义(t=8.042,P<0.001);研究组血清β-HCG转阴时间、月经恢复时间、住院时间分别为(21.33±3.78)d、(28.21±3.83)d、(6.53±2.12)d,分别短于对照组的(26.72±4.83)d、(33.82±4.91)d、(9.53±2.67)d,差异具有统计学意义(t=6.458、6.620、6.466,P均<0.001)。两组均随访≥24个月,宫内妊娠、未孕、流产、再次瘢痕子宫妊娠、异位妊娠比较,差异无统计学意义(χ2=1.895,P>0.05);宫内妊娠中足月分娩与早产比较,差异无统计学意义(χ2=0.131,P>0.05),研究组并发症发生率为22.58%,低于对照组的37.50%,差异有统计学意义(χ2=5.296,P=0.021)。结论 在宫腔镜辅助微创清宫术治疗瘢痕子宫妊娠前使用HIFU联合MTX预处理的效果优于单一使用HIFU预处理,可明显缩短患者血清β-HCG转阴时间、月经恢复时间与住院时间,但对女性的妊娠结局无影响,妇产科临床治疗前可结合患者需求择取最合适的预处理方案。  相似文献   
94.
PurposeTo show that a deep learning (DL)–based, automated model for Lipiodol (Guerbet Pharmaceuticals, Paris, France) segmentation on cone-beam computed tomography (CT) after conventional transarterial chemoembolization performs closer to the “ground truth segmentation” than a conventional thresholding-based model.Materials and MethodsThis post hoc analysis included 36 patients with a diagnosis of hepatocellular carcinoma or other solid liver tumors who underwent conventional transarterial chemoembolization with an intraprocedural cone-beam CT. Semiautomatic segmentation of Lipiodol was obtained. Subsequently, a convolutional U-net model was used to output a binary mask that predicted Lipiodol deposition. A threshold value of signal intensity on cone-beam CT was used to obtain a Lipiodol mask for comparison. The dice similarity coefficient (DSC), mean squared error (MSE), center of mass (CM), and fractional volume ratios for both masks were obtained by comparing them to the ground truth (radiologist-segmented Lipiodol deposits) to obtain accuracy metrics for the 2 masks. These results were used to compare the model versus the threshold technique.ResultsFor all metrics, the U-net outperformed the threshold technique: DSC (0.65 ± 0.17 vs 0.45 ± 0.22, P < .001) and MSE (125.53 ± 107.36 vs 185.98 ± 93.82, P = .005). The difference between the CM predicted and the actual CM was 15.31 mm ± 14.63 versus 31.34 mm ± 30.24 (P < .001), with lesser distance indicating higher accuracy. The fraction of volume present ([predicted Lipiodol volume]/[ground truth Lipiodol volume]) was 1.22 ± 0.84 versus 2.58 ± 3.52 (P = .048) for the current model’s prediction and threshold technique, respectively.ConclusionsThis study showed that a DL framework could detect Lipiodol in cone-beam CT imaging and was capable of outperforming the conventionally used thresholding technique over several metrics. Further optimization will allow for more accurate, quantitative predictions of Lipiodol depositions intraprocedurally.  相似文献   
95.
PurposeThe purpose of this study was to analyze the management and outcomes of primary button battery ingestions and their sequelae at a single high-volume center, and to propose a risk score to predict the likelihood of a severe outcome.MethodsThe medical record was queried for all patients under 21 years old evaluated at our institution for button battery ingestion from 2008 to 2021. A severe outcome was defined as having at least one of the following: deep/circumferential mucosal erosion, perforation, mediastinitis, vascular or airway injury/fistula, or development of esophageal stricture. From a selection of clinically relevant factors, logistic regression determined predictors of a severe outcome, which were incorporated into a risk model.Results143 patients evaluated for button battery ingestion were analyzed. 24 (17%) had a severe outcome. The independent predictors of a severe outcome in multivariate analysis were location of battery in the esophagus on imaging (96%), battery size >/ = 2 cm (95%), and presence of any symptoms on presentation (96%), with P < 0.001 in all cases. Predicted probability of a severe outcome ranged from 88% when all three risk factors were observed, to 0.3% when none were present.ConclusionWe report the presentation, management, and complication profiles of a large cohort of BB ingestions treated at a single institution. A risk score to predict severe outcomes may be used by providers initially evaluating patients with button battery ingestion in order to allocate resources and expedite transfer to a center with pediatric endoscopic and surgical capabilities.Level of evidenceLevel IV.Type of studyClinical Research Paper.  相似文献   
96.
《Saudi Pharmaceutical Journal》2022,30(11):1665-1671
5-fluorouracil (5FU) is widely used to treat colorectal cancer (CC) and its main mechanisms of anticancer action are through generation of ROS which often result in inflammation. Here, we test the effect of Lycopene against 5FU in Caco2 cell line. Caco2 cells were exposed to 3 µg/ml of 5FU alone or with 60, 90, 120 µg/ml of lycopene. This was followed by assessment of cytotoxicity, oxidative stress, and gene expression of inflammatory genes. Our findings showed that Lycopene and 5FU co-exposure induced dose-dependent cytotoxic effect without compromising the membrane integrity based on the LDH assay. Lycopene also significantly enhanced 5FU-induced SOD activity and GSH level compared to control for all mixture concentrations (p < 0.01). Lycopene alone and combination with 5FU-induced expression of IL-1β, TNF-α, and IL-6. Furthermore, IFN-γ expression was significantly enhanced by only mixture of lycopene (90 µg/ml) and 5FU (p < 0.05). In conclusion, Lycopene supplementation with 5FU therapy resulted in improvement in antioxidant parameters such as catalase and GSH levels giving the cell capacity to cope with 5FU-mediated oxidative stress. Lycopene also enhanced IFN-γ expression in the presence of 5FU, which may activate antitumor effects further enhancing the cancer killing effect of 5FU.  相似文献   
97.
《Clinical lung cancer》2022,23(2):122-134
Introduction: Both pembrolizumab (P) as a monotherapy or in combination with platinum-based chemotherapy (PCT) represent standard first-line treatment options for advanced non-small cell lung cancer (aNSCLC) with PD-L1 tumor proportion score (TPS)≥50%. No predictive biomarkers exist to guide treatment decisions.Methods: 423 consecutive patients with EGFR/ALK/ROS1-wild-type PD-L1 TPS≥50% aNSCLC receiving P (n = 302) or PCT (n = 121) as a first-line treatment were identified in the electronic databases of 5 Israeli cancer centers. Overall survival (OS, months [mo]) was assessed in correlation with blood biomarkers (BB: NLR, dNLR, PLR, SII, LIPI, ALI); a predictive score was developed.Results: In the propensity score matching analysis (n = 236; 118 patients in each group matched for age, sex and ECOG PS), mOS was 17.2mo (95% CI, 13.2-36.5) and 21.3mo (95% CI, 14.8-NR) in groups P and PCT, respectively (P = .44). In group P, NLR, dNLR, PLR, LIPI, and ALI significantly correlated with OS in uni- and multivariate COX regression analyses (P < .05), whereas in group PCT, none of the BB demonstrated a significant correlation. A predictive score was developed (each parameter receiving one point): age≥65, female sex, never-smoking status, adenocarcinoma histology, dNLR≥3. In patients with predictive score 3-5, OS was significantly longer with PCT as compared to P: mOS NR (95% CI, 15.3-NR) and 8.7mo (95% CI, 5.8-13.7) (P = .0005), while OS didn't differ significantly in patients with predictive score 0-2 (P = .61).Conclusion: With the limitations of the retrospective analysis, the proposed dNLR-based score appears to predict OS with P and PCT.  相似文献   
98.
目的 评价CT引导下经皮二次穿刺活检用于明确诊断肺部病变的可行性及安全性。方法 回顾性分析40例接受2次肺穿刺活检患者的临床、影像学及随访资料,根据最终诊断结果,比较2次活检的诊断准确率,分析并发症及初次活检误诊的危险因素。结果 40例中,17例初次活检诊断结果与最终诊断一致(确诊组)、23例诊断不一致(误诊组),诊断准确率为42.50%(17/40),并发症发生率为27.50%(11/40);39例二次活检诊断结果与最终诊断一致,诊断准确率为97.50%(39/40),并发症发生率为25.00%(10/40)。二次活检诊断准确率明显提高,并发症发生率与初次活检差异无统计学意义(P>0.05)。组间病灶性质和气胸发生率差异均有统计学意义(P均<0.05)。结论 CT引导下经皮二次穿刺活检用于明确诊断肺部病变安全、可行。  相似文献   
99.
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号