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   17249篇
  免费   855篇
  国内免费   690篇
耳鼻咽喉   67篇
儿科学   191篇
妇产科学   188篇
基础医学   2841篇
口腔科学   239篇
临床医学   1846篇
内科学   2173篇
皮肤病学   303篇
神经病学   624篇
特种医学   297篇
外国民族医学   4篇
外科学   564篇
综合类   2331篇
预防医学   1518篇
眼科学   122篇
药学   3788篇
  2篇
中国医学   608篇
肿瘤学   1088篇
  2023年   121篇
  2022年   203篇
  2021年   288篇
  2020年   379篇
  2019年   380篇
  2018年   339篇
  2017年   416篇
  2016年   452篇
  2015年   441篇
  2014年   884篇
  2013年   1131篇
  2012年   995篇
  2011年   1211篇
  2010年   842篇
  2009年   857篇
  2008年   840篇
  2007年   908篇
  2006年   793篇
  2005年   841篇
  2004年   740篇
  2003年   663篇
  2002年   573篇
  2001年   462篇
  2000年   403篇
  1999年   313篇
  1998年   278篇
  1997年   251篇
  1996年   224篇
  1995年   253篇
  1994年   223篇
  1993年   179篇
  1992年   187篇
  1991年   188篇
  1990年   173篇
  1989年   155篇
  1988年   142篇
  1987年   121篇
  1986年   112篇
  1985年   206篇
  1984年   148篇
  1983年   129篇
  1982年   110篇
  1981年   64篇
  1980年   49篇
  1979年   41篇
  1978年   16篇
  1977年   22篇
  1975年   6篇
  1974年   16篇
  1972年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
目的:探讨荧光免疫层析法(fluorescence immunochromatography assay,FICA)与酶联免疫吸附法(ELISA)检测英夫利西单抗(infliximab,IFX)血药浓度结果的相关性与一致性。方法:采用已上市的IFX药物浓度测定试剂盒(荧光免疫层析法)与实验室建立的检测IFX浓度的ELISA方法测定克罗恩病患者血液样本IFX浓度。通过Spearman相关分析、Passing-Bablok回归、单样本t检验、Bland-Altman散点图和Cohen's Kappa系数等对检测结果统计分析。结果:共收集到44份血液样本,FICA和ELISA法检测IFX结果的Spearman系数为0.87(P<0.01)。Passing-Bablok回归分析显示,FICA和ELISA法检测IFX结果的回归方程为CFICA=0.5071CELISA+0.6230。单样本t检验提示2种方法检测IFX结果差值与0有显著差异。Bland-Altman散点图显示FICA与ELISA法所测IFX血药浓度的差值中有91.43%(32/35)在一致性界限内(差值均值±1.96 SD)。对2种分析方法检测IFX结果定性分析表明一致性为68.18%(30/44),Cohen's KAppa系数为0.51。结论:FICA与ELISA法检测IFX结果高度相关,但一致性存在差异。ELISA法所测IFX浓度结果高于FICA,提示运用IFX检测结果进行临床决策时要关注检测方法。  相似文献   
3.
目的探讨血清基质金属蛋白酶-9(MMP-9)测定联合肺泡灌洗液Xpert MTB/RIF检测、γ-干扰素(INF-γ)释放试验对肺结核的诊断效能。方法选取2019年5月—2020年5月河北省胸科医院200例疑似肺结核患者,根据检查结果分为菌阳肺结核组(62例)、菌阴肺结核组(88例)、非肺结核组(50例),比较3组血清MMP-9、白细胞介素(IL)-15、肿瘤坏死因子α(TNF-α)、C反应蛋白(CRP)、红细胞沉降率(ESR)和INF-γ释放试验、结核分枝杆菌(MTB)培养、肺泡灌洗液Xpert MTB/RIF检测结果的差异,多因素分析采用Logistic回归分析,采用受试者工作特征(ROC)曲线评价血清MMP-9测定、肺泡灌洗液Xpert MTB/RIF检测、INF-γ释放试验单独和联合诊断肺结核的效能。结果菌阳肺结核组、菌阴肺结核组及非肺结核组MMP-9、INF-γ水平差异均有统计学意义(P<0.05),其他指标差异均无统计学意义(P>0.05)。肺结核患者MMP-9、INF-γ水平均高于非肺结核患者(P<0.05)。菌阳肺结核组Xpert MTB/RIF阳性率明显高于菌阴肺结核组(P<0.05),2个组之间INF-γ释放试验阳性率及INF-γ水平差异均无统计学意义(P>0.05)。Logistic回归分析结果显示,MMP-9[比值比(OR)值为1.687,P=0.004]、INF-γ(OR=2.511,P=0.005)和Xpert MTB/RIF(OR=1.340,P=0.005)是肺结核的危险因素。Xpert MTB/RIF检测诊断肺结核的敏感性为86.7%,特异性为96.0%,准确性为89.0%;INF-γ释放试验诊断肺结核的敏感性为80.0%,特异性为62.0%,准确性为75.5%;MMP-9诊断肺结核的敏感性为80.7%,特异性为60.0%,准确性为75.0%;3种方法联合诊断肺结核的敏感性为90.7%,特异性为78.0%,准确性为87.5%。结论MMP-9和INF-γ高表达、Xpert MTB/RIF阳性是肺结核的危险因素,3种方法联合诊断肺结核的敏感性和特异性明显增强,具有一定的临床意义。  相似文献   
4.
目的  制备抗柯萨奇病毒A组2型( coxsackievirus A2,CV-A2)单克隆抗体(单抗),建立CV-A2抗原检测方法。方法  用纯化后的CV-A2全病毒颗粒免疫小鼠,筛选获得抗CV-A2单抗。建立CV-A2抗原检测方法,确定线性范围,对其准确度、精密度、稳定性、专属性进行验证。用 ELISA检测病毒颗粒纯化过程中样品的抗原含量。结果  制备了高效价的抗CV-A2单抗并建立 ELISA抗原检测方法,检测范围为5.00~320.00 ng/ml。高、中、低3个浓度样品准确度验证回收率在89.58%~104.78%之间。重复性验证变异系数分别为2.10%、2.47%、6.18%。中间精密度验证变异系数分别为2.89%、2.69%、1.94%。耐用性验证回收率在84.26%~114.21%之间。包被微孔板于37℃放置3d,样品回收率在90.31%~103.11%之间。专属性验证结果显示该方法只识别CV-A2抗原,与其他抗原均无交叉反应。结论  建立并验证了CV-A2 ELISA抗原检测方法,可应用于病毒纯化过程中样品的抗原检测,还可应用于含CV-A2的手足口病多价疫苗的CV-A2抗原含量检测。  相似文献   
5.
PurposeCartridge based nucleic acid amplification test (CBNAAT) has been endorsed by the WHO as the screening test for diagnosing extrapulmonary tuberculosis (EPTB). In the present study we report the agreement between CBNAAT (Xpert MTB/RIF), liquid culture (LC) and line probe assay (LPA) for diagnosis of Mycobacterium tuberculosis and detection of drug resistance among EPTB cases.MethodsThe EP samples were subjected to CBNAAT (Xpert MTB/RIF, Cepheid, USA) and wherever possible, to LC (MGIT 960, Becton Dickinson, USA) followed sequentially by first line and second line-LPA (FL-LPA, SL-LPA, Hain Lifescience, Germany) on the isolates.ResultsTotal 566/4080 (13.9%) EP samples were detected positive for M. tuberculosis on CBNAAT. Aspirates from lymph nodes were most often positive (11/30; 36.6%), followed by pus (240/873; 27.5%) and CSF samples (166/104; 15.8%). The detection of M. tuberculosis was more in adults than children except in tissue biopsy samples. Rifampicin resistance was also higher among adults except CSF in which resistance was more in children. Total 185 of 566 (32.7%) CBNAAT positive and 770 of 3510 (21.9%) CBNAAT negative samples could be cultured of which 110/185 (59.4%) and 33/770 (4.3%) respectively turned positive. FL-LPA and SL-LPA of 143 culture isolates showed that 27 isolates had drug resistance, of which 3 (2.1%) were XDR, 11 (7.7%) were Pre-XDR (FQ) and 13 (9.1%) were MDR. Of these 27 resistant isolates, 12 were negative by CBNAAT and two were mislabeled as Rifampicin sensitive or indeterminate based on the unique RpoB gene mutation patterns on LPA. The positive and negative agreements between LC and CBNAAT for detection of M. tuberculosis were 67.1% and 92.7% respectively and between LPA and CBNAAT for rifampicin resistance detection were 98.9% and 92.9% respectively.ConclusionsFor EPTB, CBNAAT should be accompanied with LC wherever possible irrespective of the CBNAAT result.  相似文献   
6.
7.
《Saudi Dental Journal》2022,34(7):565-571
PurposeThis study aimed to evaluate the neuroprotective ability of the conditioned medium of stem cells from human exfoliated deciduous teeth (CM-SHED) to prevent glutamate-induced apoptosis of neural progenitors.Materials and methodsNeural progenitors were isolated from two-day-old rat brains, and the conditioned medium was obtained from a mesenchymal stem cell SHED. Four groups were examined: neural progenitor cells cultured in neurobasal medium with (N + ) and without (N-) glutamate and glycine, and neural progenitor cells cultured in CM-SHED with (K + ) and without (K-) glutamate and glycine.ResultsThe expression of GABA A1 receptor (GABAAR1) messenger RNA (mRNA) in neural progenitor measured by real-time quantitative PCR. GABA contents were measured by enzyme-linked immunosorbent assay, whereas the apoptosis markers caspase-3 and 7-aminoactinomycin D were analysed with a Muse® cell analyzer. The viability of neural progenitor cells in the K + group (78.05 %) was higher than the control group N- (73.22 %) and lower in the N + group (68.90 %) than in the control group. The K + group showed the highest GABA content, which significantly differed from that in the other groups, whereas the lowest content was observed in the N + group. The expression level of GABAAR1 mRNA in the K + group was the highest compared to that in the other groups. CM-SHED potently protected the neural progenitors from apoptosis.ConclusionsCM-SHED may effectively prevent glutamate-induced apoptosis of neural progenitors.  相似文献   
8.
9.
《Drug discovery today》2022,27(6):1733-1742
Compounds that exhibit assay interference or undesirable mechanisms of bioactivity are routinely encountered in assays at various stages of drug discovery. We observed that assays for the investigation of thiol-reactive and redox-active compounds have not been collected in a comprehensive review. Here, we review these assays and subject them to experimental optimization to improve their reliability. We demonstrate the usefulness of our assay cascade by assaying a library of bioactive compounds, chemical probes, and a set of approved drugs. These high-throughput assays should complement the array of wet-lab and in silico assays during the initial stages of hit discovery campaigns to pursue only hit compounds with tractable mechanisms of action.  相似文献   
10.
Background and aimsIntermittent fasting reduces risk of interrelated cardiometabolic diseases, including type 2 diabetes and heart failure (HF). Previously, we reported that intermittent fasting reduced homeostasis model assessment of insulin resistance (HOMA-IR) and Metabolic Syndrome Score (MSS) in the WONDERFUL Trial. Galectin-3 may act to reduce insulin resistance. This post hoc evaluation assessed whether intermittent fasting increased galectin-3.Methods and resultsThe WONDERFUL Trial enrolled adults ages 21–70 years with ≥1 metabolic syndrome features or type 2 diabetes who were not taking anti-diabetic medication, were free of statins, and had elevated LDL-C. Subjects were randomized to water-only 24-h intermittent fasting conducted twice-per-week for 4 weeks and once-per-week for 22 weeks or to a parallel control arm with ad libitum energy intake. The study evaluated 26-week change scores of galectin-3 and other biomarkers. Overall, n = 67 subjects (intermittent fasting: n = 36; control: n = 31) completed the trial and had galectin-3 results. At 26-weeks, the galectin-3 change score was increased by intermittent fasting (median: 0.793 ng/mL, IQR: ?0.538, 2.245) versus control (median: ?0.332 ng/mL, IQR: ?0.992, 0.776; p = 0.021). Galectin-3 changes correlated inversely with 26-week change scores of HOMA-IR (r = ?0.288, p = 0.018) and MSS (r = ?0.238, p = 0.052). Other HF biomarkers were unchanged by fasting.ConclusionA 24-h water-only intermittent fasting regimen increased galectin-3. The fasting-triggered galectin-3 elevation was inversely correlated with declines in HOMA-IR and MSS. This may be an evolutionary adaptive survival response that protects human health by modifying disease risks, including by reducing inflammation and insulin resistance.Trial registrationClinicaltrials.gov, NCT02770313 (registered on May 12, 2016; first subject enrolled: November 30, 2016; final subject's 26-week study visit: February 19, 2020).  相似文献   
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