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   7561篇
  免费   906篇
  国内免费   470篇
耳鼻咽喉   40篇
儿科学   84篇
妇产科学   101篇
基础医学   747篇
口腔科学   99篇
临床医学   940篇
内科学   1050篇
皮肤病学   62篇
神经病学   265篇
特种医学   394篇
外国民族医学   1篇
外科学   628篇
综合类   1560篇
一般理论   4篇
预防医学   723篇
眼科学   174篇
药学   813篇
  7篇
中国医学   691篇
肿瘤学   554篇
  2024年   49篇
  2023年   172篇
  2022年   465篇
  2021年   539篇
  2020年   409篇
  2019年   294篇
  2018年   331篇
  2017年   310篇
  2016年   263篇
  2015年   381篇
  2014年   455篇
  2013年   444篇
  2012年   639篇
  2011年   619篇
  2010年   380篇
  2009年   333篇
  2008年   406篇
  2007年   418篇
  2006年   273篇
  2005年   295篇
  2004年   201篇
  2003年   187篇
  2002年   162篇
  2001年   131篇
  2000年   100篇
  1999年   105篇
  1998年   73篇
  1997年   67篇
  1996年   65篇
  1995年   54篇
  1994年   37篇
  1993年   27篇
  1992年   40篇
  1991年   27篇
  1990年   22篇
  1989年   33篇
  1988年   31篇
  1987年   19篇
  1986年   23篇
  1985年   9篇
  1984年   4篇
  1983年   5篇
  1982年   10篇
  1981年   8篇
  1980年   3篇
  1979年   3篇
  1978年   3篇
  1977年   5篇
  1976年   4篇
  1975年   4篇
排序方式: 共有8937条查询结果,搜索用时 15 毫秒
21.
目的研究腺样体肥大患儿血清炎症介质、淋巴细胞亚群表达特征及其与患儿预后的相关性。方法选取浙江中医药大学附属第三医院收治的86例腺样体肥大患儿(观察组)和86例健康儿童(对照组)作为研究对象,采集血液标本测定血清炎症介质及淋巴细胞亚群相关指标,对比两组儿童的测定结果。分析腺样体肥大患儿的肥大程度、腺样体再增生情况,对比不同肥大程度患儿的血清指标,并分析各指标与患儿病情程度及预后(腺样体再增生)的关系。结果观察组患儿肿瘤坏死因子-α(TNF-α)、可溶性白细胞介素-2受体(sIL-2R)及白细胞介素-6(IL-6)水平分别为(492.44±50.56)mg/L、(420.48±61.79)U/ml及(33.65±4.51)pg/ml,对照组儿童分别为(301.22±41.65)mg/L、(236.55±57.90)U/ml及(16.25±3.27)pg/ml,差异均有统计学意义(t=16.004,P<0.05;t=20.311,P<0.05;t=8.995,P<0.05)。观察组CD4+、CD8+及CD4+/CD8+水平分别为(35.75±7.05)、(16.22±2.69)及(1.46±0.67),对照组分别为(34.25±4.53)、(17.62±2.35)及(1.40±0.62),差异均无统计学意义(t=1.036,P>0.05;t=0.905,P>0.05;t=0.823,P>0.05)。相比腺样体中度肥大患儿,重度肥大患儿的TNF-α、sIL-2R、IL-6、CD4+及CD4+/CD8+水平明显更高(P<0.05)。相比未增生患儿,腺样体再增生患儿的TNF-α、sIL-2R、IL-6、CD4+及CD4+/CD8+水平明显更高(P<0.05)。相关分析显示,患儿腺样体肥大程度与TNF-α、sIL-2R、IL-6、CD4+及CD4+/CD8+水平均呈正相关(P<0.05)。患儿腺体再增生与TNF-α、sIL-2R、IL-6、CD4+及CD4+/CD8+水平也呈正相关(P<0.05)。结论腺样体肥大患儿的血清炎症介质及部分T淋巴细胞亚群表达显著升高,其与腺样体肥大程度、患儿预后密切相关。  相似文献   
22.
本文总结了北京大学口腔医学院3届八年制口腔医学专业学生口腔固定修复学临床前期实习教学的经验,针对实习中出现的典型问题进行了分析,采取了相应的对策和方法,取得了良好的效果.  相似文献   
23.
龚伟  任聪  马姗姗  李峰 《中国现代中药》2023,25(8):1707-1711
目的:基于电子鼻技术对不同品质鹿茸饮片气味特征进行分析与表征。方法:采用PEN3型电子鼻系统,分析22批鹿茸样品的气味特征,以对传感器响应值为指标,进行传感器区别贡献率分析(Loadings)、主成分分析(PCA)、线性判别分析(LDA)。结果:Loadings分析表明,5个传感器对鹿茸饮片气味特征具有较好的响应,不同规格鹿茸饮片气味差异贡献率主要体现为氮氧化物类、甲烷等短链烷烃、有机硫化物、醇醚醛酮类、芳香成分、无机硫化物等成分;PCA表明不同品种与规格鹿茸饮片,其气味的差异性比较明显;LDA发现不同品种及规格鹿茸饮片(除梅花鹿白片与粉片外)样品的气味差异均较明显,表明构成气味的物质存在差异性。结论:电子鼻技术可阐明不同品质鹿茸饮片气味的物质基础;不同品质鹿茸饮片气味存在差异性可揭示鹿茸饮片气味的科学内涵并为其质量控制提供参考。  相似文献   
24.
目的 研究落花生根内生真菌Fusarium oxysporum LHS-P1-3的次级代谢产物及其生物活性。方法 使用硅胶色谱柱、高效液相色谱等对代谢粗提物进行分离纯化,采用质谱、核磁共振等方法测定化合物的结构,采用CCK-8法测试化合物的抗肿瘤细胞活性,使用表面等离子共振实验(surface plasmon resonance,SPR)研究化合物与胆固醇转运蛋白1(niemann-pick c1-like 1,NPC1L1)相互作用关系。结果 从落花生根内生真菌Fusarium oxysporum LHS-P1-3分离得到6个化合物,包括1个新化合物(1)与5个已知化合物:白僵菌素(2)、恩镰孢菌素I(3)、恩镰孢菌素MK1688(4)、恩镰孢菌素H(5)及恩镰孢菌素B(6)。化合物14对HepG2细胞和HeLa细胞的IC50均小于10 μmol/L,化合物24则对HCT116细胞的IC50小于10 μmol/L,SPR研究表明化合物24在20 μmol/L浓度下,可与NPC1L1蛋白相互作用。结论 化合物1为新的恩镰孢菌素类化合物,命名为恩镰孢菌素W。化合物15具有抗肿瘤活性,化合物24与NPC1L1蛋白存在相互作用,可能是NPC1L1蛋白的潜在抑制剂。  相似文献   
25.
ObjectiveThe current study investigated the role of CircCDR1as on angiogenesis of bone microvascular endothelial cells (BMECs) isolated from non‐traumatic ONFH.MethodsForty corticosteroid‐induced ONFH patients received THA were enrolled in our study. Expressions of CircCDR1as, miR‐135b, and FIH‐1 were detected by qRT‐PCR in affected necrosis tissue and non‐affected normal tissue. Bone microvascular endothelial cells (BMEC) were isolated from six patients and treated with 0.1 mg/mL hydrocortisone to establish a GC‐damaged model of BMECs. Circ CDR1as plasmid and miR‐135b mimic were transfected into BMECs. BMEC proliferation was assessed using MTT assays. The migration ability of cells was detected by scratch‐wound assays. Matrigel assay was performed to detect angiogenesis in vitro. Western blot assay was used to detect HIF‐1α, VEGF, and FIH‐1 expressions. FISH, RNA pull down, RIP, and luciferase assay were carried out to determine the interaction of CircCDR1as, miR‐135b, and FIH‐1.ResultsCircCDR1as was upregulated(2.02 ± 0.30 vs. 1.00 ± 0.10,P < 0.001) whereas miR‐135b was downregulated (0.55 ± 0.12 vs. 1.00 ± 0.10,P < 0.001) in affected tissues than in non‐affected tissues. Expression of CircCDR1as and FIH‐1 were negatively associated with miR‐135b in affected tissues (CircCDR1as with miR‐135b: r = −0.506, P < 0.001; FIH‐1 with miR‐135b r = −0.510, P < 0.001). Total blood tubule density was increased when CircCDR1as was silenced compared with NC (P < 0.01 vs. NC). The number of migrated BMECs were significantly increased in CircCDR1as silencing group compared with NC group (P < 0.05 vs. NC). In addition, CircCDR1as plasmids transfection increased the protein expressions of FIH‐1 (P < 0.05 vs. NC) and reduced the HIF‐1α as well as VEGF expression compared with NC group (P < 0.05 vs. NC). FISH, RNA pull down, RIP, and luciferase assay identified that FIH‐1 was a target of miR‐135b and could be modulated by CircCDR1as.ConclusionCircCDR1as decreases angiogenesis and proliferation of BMECs by sponging miR‐135b and upregulate FIH‐1.  相似文献   
26.
BackgroundROTAVAC® is derived from human 116E rotavirus (RV) neonatal strain. In this study, we evaluated the immunogenicity, safety and reactogenicity of ROTAVAC® in Vietnam.MethodWe conducted a phase IV clinical trial in healthy infants aged 6–8 weeks using the complete regimen of ROTAVAC® with three doses. Serum anti-RV IgA was measured by enzyme-linked immunosorbent assay to assess the geometric mean concentration in infants who received the complete regimen of the vaccine.ResultsA total of 360 participants were enrolled in this clinical trial. The mean age ± standard deviation at enrollment was 6.9 ± 0.6 weeks. The anti-RV IgA titer was 4.01 ± 3.74 mg/ml pre-vaccination and substantially increased to 29.27 ± 80.64 mg/ml post-vaccination. The value of logIgA significantly increased (p = 0.003) from 0.28 ± 0.79 to 1.03 ± 0.54. The proportion of participants with equal to and greater than 3-fold and 4-fold shifts in pre- to post-vaccination antibody titer (IgA) were 55.4% and 48.3%, respectively. No adverse events or serious adverse events were recorded immediately within 30 min after the administration of each dose. The most common adverse events within 14 days after each visit were fever, unusual crying and irritability. Other adverse events occurred at a low rate, and no case of intussusception was noted.ConclusionsThe complete regimen of ROTAVAC® demonstrated an immunological response with clinically acceptable safety profile. Post-completion of this study, ROTAVAC® is now a WHO-prequalified vaccine and available in Vietnam.  相似文献   
27.
Twenty-one dogs were used to study the osteoinductivity and biomechanical properties of a biphasic porous ceramic with autogenic periosteum implanted in muscle. The ceramic implants were swathed in fresh periosteum derived from the same animals and implanted in the femur muscles. The other two groups of animals served as controls using the same material implanted in the femur bones and muscles without periosteum. Biomechanical measurements showed that, in the muscles, the experimental group had a higher bending strength than the unswathed group by the time the samples were harvested. Six months postoperatively, the strength of the samples in the experimental group had almost reached that of normal bones. The results of X-ray diffraction and infrared spectrometric analysis suggested that the degradation rate and speed of tricalcium phosphate (TCP) of the ceramic in the experimental group were faster than in the unswathed samples, but slower than in samples implanted in bones. The bone replacement and bone-inducing activity were excellent in the periosteum-swathed samples. Histologically, satisfactory bone repair was seen in the experimental samples. All results indicate that autogenic periosteum could increase bioactivity of ceramics in heterosites and improve bone formation in the surroundings of porous calcium phosphate ceramics. The data also infer that the complicated procedure of culturing bone growth factors with biomaterials in vitro to obtain bioactive grafts could be replaced by this relatively simple method.  相似文献   
28.
Peanut allergy is one of the most severe food allergies due to its persistency and life-threatening character. Serum IgE from patients with documented peanut hypersensitivity reactions and synthetic peptides were used to screen the linear IgE-binding epitopes on the major peanut allergen, Ara h 1. Five major epitopes that bound peanut-specific serum IgE from more than 60% of patients tested were identified. Mutational analysis of the immunodominant epitope showed that single amino acid changes had dramatic effects on IgE-binding characteristics. Mapping and characterisation of the IgE-binding epitopes on Ara h1 could be used in future immunotherapeutic approaches for peanut allergy disease.  相似文献   
29.
目的 评价先心病儿心脏手术前后脑电图 (EEG)、脑干听觉诱发电位 (BAEP)的变化。方法 对 30例先心病儿童术前EEG、BAEP的变化和 2 0例接受不停跳体外循环心内直视手术患儿手术前后EEG、BAEP的动态变化进行对比观察 ,并设 30名健康儿童为对照。结果  ( 1)术前 :①EEG :发绀组 (CCHD)异常率为 80 % ( 8/ 10 ) ,非发绀组 (NCCHD)异常率为 30 % ( 6 / 2 0 ) ,有显著性差异(P <0 .0 5 )。②BAEP :CCHD组异常率为 10 0 % ( 10 / 10 ) ,NCCHD异常率为 6 5 % ( 13/ 2 0 ) ,有显著性差异 (P <0 .0 5 ) ,Ⅴ波潜伏期 (PL)、Ⅲ~Ⅴ、Ⅰ~Ⅴ波峰间潜伏期 (IPL)先心病患儿与对照组比较 ,CCHD组显著延长 (P <0 .0 5 )。③EEG与BAEP :EEG异常者BAEP均异常 ( 10 0 % ) ,EEG正常者BAEP有 5 6 .3 %异常。 ( 2 )手术前后比较 ,EEG和BAEP异常率有显著性差异 (P <0 .0 5 )。结论 ①先心病患儿伴有脑功能异常 ,CCHD较NCCHD为重。②EEG与BAEP均可反映脑功能异常改变但非同步。③术后短期内EEG、BAEP无好转 ,提示脑功能恢复可能需要较长时间。  相似文献   
30.
Cong W  Wu M  Wang Y  Chen H  Zhang X 《Oncology reports》1997,4(3):649-652
Until now, no large series studies on the clinicopathological features of primary liver tumors (PLTs) in mainland China have been reported. The authors retrospectively investigated 3,160 cases of PLTs surgically resected at Shanghai Oriental Hospital of Hepatobiliary Surgery between January 1982 and January 1996. Most of them are true neoplasms, others are tumor-like lesions. The 3,160 cases of PLTs could be divided into 3 groups of 25 types arising from three germinal layers, of which tumor-like lesions (Group 1) were of 4 types involving 112 cases (3.5%), benign PLTs (Group 2) were of 10 types involving 499 cases (15.8%) and malignant PLTs (Group 3) were of 11 types involving 2,549 cases (80.7%). The most common type of lesion in each group was solitary necrotic nodule, cavernous hemangioma and hepatocellular carcinoma (HCC), accounting for 73.2%, 74.3% and 96.6% of their respective groups. The patients ranged in age from 5 months to 79 years (mean, 45.7 years), but the age distribution and sex ratio varied reciprocally from group to group and from lesion to lesion. For example, the mean age of the patients in Group 1 was 39.1 years of age, whereas in Group 2 and Group 3, it was 45.9 years and 49.6 years, respectively. The sex ratio of men to women was 2.6:1 in Group 1, 1:1.1 in Group 2 and 7.7:1 in Group 3. The rates of serum HBsAg positivity and concomitant liver cirrhosis in the patients with HCC were 74.4% and 72%, respectively, and the concomitant rate of cirrhosis in small HCC (<3 cm in diameter) was as high as 83.3% (P<0.05), demonstrating a close relationship of HCC with HBV infection and liver cirrhosis. HCC amounts to 78.4% of the total 3,160 PLTs in this series, indicating that HCC is the most common malignant tumor of the liver in China.  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