全文获取类型
收费全文 | 23694篇 |
免费 | 1528篇 |
国内免费 | 1216篇 |
专业分类
耳鼻咽喉 | 420篇 |
儿科学 | 216篇 |
妇产科学 | 380篇 |
基础医学 | 1677篇 |
口腔科学 | 187篇 |
临床医学 | 1948篇 |
内科学 | 3316篇 |
皮肤病学 | 184篇 |
神经病学 | 248篇 |
特种医学 | 1621篇 |
外国民族医学 | 22篇 |
外科学 | 4045篇 |
综合类 | 4095篇 |
预防医学 | 560篇 |
眼科学 | 74篇 |
药学 | 1110篇 |
1篇 | |
中国医学 | 172篇 |
肿瘤学 | 6162篇 |
出版年
2024年 | 6篇 |
2023年 | 210篇 |
2022年 | 382篇 |
2021年 | 647篇 |
2020年 | 719篇 |
2019年 | 589篇 |
2018年 | 557篇 |
2017年 | 556篇 |
2016年 | 652篇 |
2015年 | 655篇 |
2014年 | 1392篇 |
2013年 | 1112篇 |
2012年 | 1142篇 |
2011年 | 1390篇 |
2010年 | 1251篇 |
2009年 | 1376篇 |
2008年 | 1506篇 |
2007年 | 1702篇 |
2006年 | 1548篇 |
2005年 | 1303篇 |
2004年 | 1151篇 |
2003年 | 999篇 |
2002年 | 871篇 |
2001年 | 841篇 |
2000年 | 678篇 |
1999年 | 501篇 |
1998年 | 415篇 |
1997年 | 360篇 |
1996年 | 289篇 |
1995年 | 228篇 |
1994年 | 220篇 |
1993年 | 161篇 |
1992年 | 132篇 |
1991年 | 117篇 |
1990年 | 88篇 |
1989年 | 69篇 |
1988年 | 73篇 |
1987年 | 76篇 |
1986年 | 70篇 |
1985年 | 71篇 |
1984年 | 56篇 |
1983年 | 35篇 |
1982年 | 54篇 |
1981年 | 52篇 |
1980年 | 41篇 |
1979年 | 26篇 |
1978年 | 21篇 |
1977年 | 18篇 |
1976年 | 12篇 |
1975年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
目的 观察双能量CT (DECT)定量参数术前预测实性肺腺癌气道播散(STAS)状态的价值。方法 回顾性分析52例经手术病理确诊实性肺腺癌患者的DECT及病理学资料,评估其STAS状态(阳性或阴性);对比STAS阳性、阴性实性肺腺癌CT表现(最大径、周围不透明影、空气支气管征、胸膜凹陷征)及DECT定量参数的差异。针对差异有统计学意义的DECT定量参数绘制受试者工作特征(ROC)曲线,计算曲线下面积(AUC),评估DECT定量参数单独及联合预测实性肺腺癌STAS的效能,并以二元logistic回归分析筛选实性肺腺癌STAS的独立预测因子。结果 52例中,25例STAS阳性,27例STAS阴性,其间病灶CT表现差异均无统计学意义(P均>0.05),DECT定量参数中的动脉期碘浓度(ICA)、动脉期标准化碘浓度(NICA)及静脉期碘浓度(ICV)差异均有统计学意义(P均<0.05)。ICA、NICA及ICV预测实性肺腺癌STAS的AUC为0.82、0.83及0.73;ICA和NICA均为实性肺腺癌STAS的独立预测因子,其联合AUC为0.89。结论 DECT定量参数可有效预测实性肺腺癌STAS。 相似文献
2.
目的通过体内和体外研究探讨羟基红花黄色素(hydroxy safflower yellow A,HSYA)在大鼠应激性结肠高动力中的作用及其可能的作用机制。方法将15只雄性Wistar大鼠分为3组,分别为:SWAS(假性避水应激)组、WAS(避水应激)组、WAS+HSYA组,每组5只。WAS组和SWAS组大鼠连续10 d每天分别暴露于避水应激和假性避水应激中1 h,建立大鼠模型;WAS+HSYA组大鼠于每天进行避水应激前半小时,以60 mg/kg的HSYA灌胃,而WAS组以相同的生理盐水灌胃,SWAS组则不做处理。整个实验期间,分别记录各组大鼠的每天粪球排出量。于实验第11天,大鼠处死后取近端结肠制备肌条,以张力换能器测定结肠平滑肌肌张力变化。另取正常大鼠离体近端结肠制备肌条,以张力换能器测定结肠平滑肌肌张力变化,当出现一段规律收缩信号后,分别进行其他的相关处理:(1)加入浓度梯度的HSYA溶液(终浓度分别为0.6、1.2、1.8 mol/L),观察并记录其自发性收缩活性变化;(2)用1μmol/L TTX孵育肌条10 min,再以浓度梯度的HSYA溶液处理肌条,观察并记录其自发性收缩活性变化;(3)用30μmol/L Tak-242孵育肌条15 min,再以浓度梯度的HSYA溶液处理肌条,观察并记录其自发性收缩活性的变化。采用SPSS 26.0统计软件、Graphpad 8.0软件对实验所得数据进行分析。结果避水应激诱发大鼠结肠动力亢进。HSYA明显抑制结肠肌条收缩活性,这种作用未被TTX阻断,而TLR4受体拮抗剂Tak-242能显著阻断HSYA对结肠肌条收缩活性的抑制作用。结论 HSYA能逆转应激性结肠动力亢进,这种效应可能与TLR4受体通路有关。 相似文献
3.
4.
《Cirugía espa?ola》2023,101(5):325-332
IntroductionIn our institution, the study of selective sentinel node biopsy (SLNB) is performed intraoperatively. The main objective of our study is to know the proportion of patients who benefits from the waiting of the results of SLNB.MethodsA retrospective analysis of patients operated on our center between January 1 st, 2018 and June 30, 2019 was carried out. We included women diagnosed with T1–T2 tumors, treated by lumpectomy and SLNB studied using OSNA method.ResultsOur study included 149 women. There were not statistically significant differences in terms of demographic data between the group treated with axillary lymph node dissection (ALND) and exclusively SLNB group. After analysis of SLN intraoperatively, there were performed 18 axillary lymphadenectomies. Only in six of these 18 cases, three or more sentinel nodes were founded. The location of the tumor, the presence of lymphovascular permeation and the total tumor load (TTL) showed statistically significant differences between groups. Only the TTL was established as the independent factor of the need for ALND.ConclusionsObtaining a deferred result of the SLNB allowed reducing the time of anesthesia and occupation of the operating room, since in a high percentage of cases an additional procedure is not performed. 相似文献
5.
6.
地鳖中的纤溶活性蛋白是从地鳖中提取的具有抗栓及抗肿瘤作用的有效成分,其口服易被上消化道酶分解从而限制了应用。采用恒流泵滴制法开发地鳖纤溶活性蛋白时间/pH依赖口服结肠靶向微囊(EnpolypHaga fibrinolytic protein oral colon targeting microcapsules, CTM-EFP)。采用单因素实验和正交实验相结合的方法寻找到包封率为60.17 % ± 2.72 %、载药量为15.50 % ± 0.44 % 的最佳配方。扫描电子显微镜(SEM)显示微囊呈球形、表面光滑,在人工肠液中24 h的累积释放度为99.53 % ± 0.69 %,在人工胃液中24 h累积释放度为7.43 ± 1.04 %,通过时间/pH依赖达到结肠靶向作用。CTM-EFP在人工肠液中的体外释放曲线符合Korsmeyer方程,提示地鳖纤溶活性蛋白(EnpolypHaga fibrinolytic protein, EFP)是通过扩散和侵蚀机制结合释放的。CTM-EFP为EFP的口服给药提供了一种新的剂型,为EFP应用于临床提供参考。 相似文献
7.
8.
《International journal of medical microbiology : IJMM》2022,312(2):151549
BackgroundAdvances in genome sequencing have enabled detailed microbiome analysis; however, the ideal specimen type for sequencing is yet to be determined. Rectal swabs may offer a rapid and convenient modality for colonic microbiome analysis. The aim of this study is to evaluate the use of rectal swabs compared to faecal specimens.Methods and resultsTwenty health professionals participated in this study and provided a faecal specimen, a self-collected rectal swab and a rectal swab taken by a clinician. DNA was extracted and 16S rRNA gene sequencing was carried out for microbiome analysis.Alpha diversity was higher in swabs compared to faecal specimens; however, the difference was only significant when comparing clinician-obtained swabs to faeces.Analysis of beta diversity consistently showed that few taxa were affected by sample type. We found sample type accounted for only 6.8% of community variation (R2 = 0.067, p < 0.001, permanova). Notably, there were only six genera identified in clinician-obtained swabs that were not also found in the self-taken swabs.ConclusionsBoth self-collected and clinician obtained rectal swabs are a reliable method of analysing the colonic microbiome. Obtaining specimens for microbiome analysis is often time-critical due to therapy, such as antibiotics, influencing the microbiome. Rectal swabs are shown to be a valid and convenient modality for microbiome analysis. 相似文献
9.
《Journal of pediatric surgery》2023,58(7):1258-1262
BackgroundIt is well known that small bowel length is a dominant prognostic indicator in patients with short bowel syndrome (SBS). The relative importance of jejunum, ileum, and colon is less well defined in children with SBS. Here we review the outcome of children with SBS with respect to the type of remnant intestine.MethodsA retrospective review of 51 children with SBS was conducted at a single institution. The duration of parenteral nutrition use was the main outcome variable. The length of the remaining intestine as well as the type of intestine were recorded for each patient. Kaplan–Meier analyses were conducted to compare the subgroups.ResultsChildren with greater than 10% expected small bowel length or more than 30 cm of small bowel achieved enteral autonomy faster than those with less. The presence of ileocecal valve enhanced the ability to wean from parenteral nutrition. The presence of ileum significantly enhanced the ability to wean from parenteral nutrition. Patients with the entire colon also achieved enteral autonomy sooner than those with partial colon.ConclusionsThe preservation of ileum and colon is important in patients with SBS. Approaches to preserve or lengthen ileum and colon may be beneficial for these patients.Level of evidenceIV. 相似文献
10.
目的 观察不同T、M分期前列腺癌小视野体素内不相干运动(IVIM)弥散加权成像(DWI)参数特征。方法 回顾性分析46例接受前列腺MR常规序列成像和小视野IVIM-DWI的不同临床T、M分期及Gleason评分前列腺癌患者,观察其间标准表观弥散系数(ADCstandard)、扩散系数(D)、伪扩散系数(D*)及快速扩散分数(f)差异,分析临床T、M分期及Gleason评分与上述参数的相关性。结果 不同T分期前列腺癌ADCstandard、D及f差异具有统计学意义(P均<0.05);其中,ADCstandard和f在T2与T3期、T2与T4期之间差异均有统计学意义(P均<0.05),D在T2与T4期、T3与T4期之间差异均有统计学意义(P均<0.05)。不同M分期及不同Gleason评分前列腺癌ADCstandard和D差异均有统计学意义(P均<0.05)。前列腺癌T分期与ADCstandard、D及f呈负相关(r=-0.69、-0.75、-0.53,P均<0.05),M分期和Gleason评分均与ADCstandard(r=-0.34、-0.50,P均<0.05)及D (r=-0.43、-0.53,P均<0.05)呈负相关。结论 不同T分期前列腺癌ADCstandard、D及f存在差异,且T分期与三者均呈负相关;不同M分期前列腺癌ADCstandard和D存在差异,且M分期与二者均呈负相关。 相似文献