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   10228篇
  免费   989篇
  国内免费   304篇
耳鼻咽喉   59篇
儿科学   159篇
妇产科学   281篇
基础医学   1208篇
口腔科学   135篇
临床医学   1171篇
内科学   1543篇
皮肤病学   77篇
神经病学   447篇
特种医学   260篇
外国民族医学   3篇
外科学   1374篇
综合类   1314篇
现状与发展   3篇
预防医学   868篇
眼科学   44篇
药学   715篇
  13篇
中国医学   350篇
肿瘤学   1497篇
  2024年   23篇
  2023年   136篇
  2022年   302篇
  2021年   439篇
  2020年   407篇
  2019年   359篇
  2018年   326篇
  2017年   397篇
  2016年   456篇
  2015年   425篇
  2014年   789篇
  2013年   812篇
  2012年   549篇
  2011年   684篇
  2010年   512篇
  2009年   517篇
  2008年   512篇
  2007年   524篇
  2006年   438篇
  2005年   349篇
  2004年   303篇
  2003年   288篇
  2002年   232篇
  2001年   212篇
  2000年   174篇
  1999年   148篇
  1998年   134篇
  1997年   105篇
  1996年   110篇
  1995年   93篇
  1994年   91篇
  1993年   66篇
  1992年   71篇
  1991年   63篇
  1990年   53篇
  1989年   54篇
  1988年   39篇
  1987年   45篇
  1986年   33篇
  1985年   50篇
  1984年   39篇
  1983年   36篇
  1982年   36篇
  1981年   26篇
  1980年   16篇
  1979年   14篇
  1978年   15篇
  1977年   5篇
  1976年   3篇
  1975年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Weight loss is a major focus of research and public health efforts. Time-restricted eating (TRE) is shown to be effective for weight loss, but the impact on bone is unclear. Short-term TRE studies show no effect on bone mineral density (BMD), but no study has measured bone turnover markers. This secondary analysis examined the effect of 12 weeks of TRE vs. unrestricted eating on bone turnover and BMD. Overweight and obese adults aged 18–65 y (n = 20) were randomized to TRE (ad libitum 8-h eating window) or non-TRE. Serum N-terminal propeptide of type I collagen (P1NP), cross-linked N-telopeptide of type I collagen (NTX), and parathyroid hormone (PTH) levels were measured and dual-energy X-ray absorptiometry (DXA) scans were taken pre- and post-intervention. In both groups, P1NP decreased significantly (p = 0.04) but trended to a greater decrease in the non-TRE group (p = 0.07). The treatment time interaction for bone mineral content (BMC) was significant (p = 0.02), such that BMC increased in the TRE group and decreased in the non-TRE group. Change in P1NP was inversely correlated with change in weight (p = 0.04) overall, but not within each group. These findings suggest that TRE does not adversely affect bone over a moderate timeframe. Further research should examine the long-term effects of TRE on bone.  相似文献   
92.
The purpose of this study is evaluate the efficacy and safety of medicinal products containing the original Age-Related Eye Disease group (AREDS) formulation at doses approved in Europe (EU, control group; n = 59) with a product that adds DHA, lutein, zeaxanthin, resveratrol and hydroxytyrosol to the formula (intervention group; n = 50). This was a multicenter, randomized, observer-blinded trial conducted in patients aged 50 years or older diagnosed with unilateral exudative Age related Macular Degeneration AMD. At month 12, the intervention did not have a significant differential effect on visual acuity compared with the control group, with an estimated treatment difference in Early Treatment Diabetic Retinopathy Study (ETDRS) of −1.63 (95% CI −0.83 to 4.09; p = 0.192). The intervention exhibited a significant and, in most cases, relevant effect in terms of a reduction in some inflammatory cytokines and a greater improvement in the fatty acid profile and serum lutein and zeaxantin concentration. In patients with unilateral wet AMD, the addition of lutein, zeaxanthin, resveratrol, hydroxytyrosol and DHA to the AREDS EU recommended doses in the short-term did not have a differential effect on visual acuity compared to a standard AREDS EU formula but, in addition to improving the fatty acid profile and increasing carotenoid serum levels, may provide a beneficial effect in improving the proinflammatory and proangiogenic profile of patients with AMD.  相似文献   
93.
Background: A disequilibrium of the gut microbial community has been closely associated with systemic inflammation and metabolic syndromes including type 2 diabetes. While low fibre and high fat diets may lead to dysbiosis of the gut microbiome as a result of the loss of useful microbes, it has been reported that a high fibre diet may prevent the fermentation of protein and may promote eubiosis of gut microbiota. Aim: This review aims to evaluate the effect of dietary fibre (DF) on gut microbiota, lipid profile, and inflammatory markers in patients with type 2 diabetes. Methods: The PRISMA framework was relied on to conduct this systematic review and meta-analysis. Searches were carried out using electronic databases and reference list of articles. Results: Eleven studies were included in the systematic review, while ten studies were included in the meta-analysis. The findings revealed five distinct areas including the effects of DF on (a) gut microbiota (122 participants); (b) lipopolysaccharides (LPS, 79 participants) and lipopolysaccharides binding protein (LBP, 81 participants); (c) lipid profile; (d) inflammatory markers; and (e) body mass index (BMI, 319 participants). The relative abundance of Bifidobacterium increased by 0.73 (95% CI: 0.57, 0.89) in the DF group in contrast to the control (p < 0.05). With respect to LPS, the level was lower in the DF group than the control and the difference was significant (p < 0.05). The standardised mean difference for LPS was −0.45 (95% CI: −0.90, −0.01) although the difference between the two groups in relation to LBP was not significant (p = 0.08) and the mean difference was 0.92 (95% CI: −0.12, 1.95). While there was a decrease of −1.05 (95% CI: −2.07, −0.02) with respect to total cholesterol (356 participants) in the DF group as compared with the control (p < 0.05), both groups were not significantly different (p > 0.05) in the other lipid parameters. The difference between the groups was significant (p < 0.05) in relation to C-reactive protein, and the mean difference was 0.43 (95% CI: 0.02, 0.84). This could be due to the short duration of the included studies and differences in participants’ diets including the amount of dietary fibre supplements. However, the groups were not significantly different (p > 0.05) with respect to the other inflammatory markers. The meta-analysis of the BMI showed that the DF group decreased by −0.57 (95% CI: −1.02, −0.12) as compared with the control and this was significant (p < 0.01). Conclusion: DF significantly (p < 0.05) increased the relative abundance of Bifidobacterium and significantly decreased (p < 0.05) LPS, total cholesterol, and BMI as compared with the control. However, DF did not seem to have an effect that was significant on LBP, triglyceride, HDL cholesterol, LDL cholesterol, IL-6, TNF-α, adiponectin, and leptin. These findings have implications for public health in relation to the use of dietary fibre in nutritional interventions and as strategies for managing type 2 diabetes.  相似文献   
94.
In patients with phenylketonuria (PKU), treated by diet therapy only, evidence suggests that areal bone mineral density (BMDa) is within the normal clinical reference range but is below the population norm. Aims: To study longitudinal bone density, mass, and geometry over 36 months in children with PKU taking either amino acid (L-AA) or casein glycomacropeptide substitutes (CGMP-AA) as their main protein source. Methodology: A total of 48 subjects completed the study, 19 subjects in the L-AA group (median age 11.1, range 5–16 years) and 29 subjects in the CGMP-AA group (median age 8.3, range 5–16 years). The CGMP-AA was further divided into two groups, CGMP100 (median age 9.2, range 5–16 years) (n = 13), children taking CGMP-AA only and CGMP50 (median age 7.3, range 5–15 years) (n = 16), children taking a combination of CGMP-AA and L-AA. Dual X-ray absorptiometry (DXA) was measured at enrolment and 36 months, peripheral quantitative computer tomography (pQCT) at 36 months only, and serum blood and urine bone turnover markers (BTM) and blood bone biochemistry at enrolment, 6, 12, and 36 months. Results: No statistically significant differences were found between the three groups for DXA outcome parameters, i.e., BMDa (L2–L4 BMDa g/cm2), bone mineral apparent density (L2–L4 BMAD g/cm3) and total body less head BMDa (TBLH g/cm2). All blood biochemistry markers were within the reference ranges, and BTM showed active bone turnover with a trend for BTM to decrease with increasing age. Conclusions: Bone density was clinically normal, although the median z scores were below the population mean. BTM showed active bone turnover and blood biochemistry was within the reference ranges. There appeared to be no advantage to bone density, mass, or geometry from taking a macropeptide-based protein substitute as compared with L-AAs.  相似文献   
95.
宫颈癌是最常见的妇科恶性肿瘤之一。目前人乳头瘤病毒(HPV)检测及细胞学检查是宫颈癌及其癌前病变(CCPL)的主要筛查手段。由于上述传统筛查方法,仍然存在对CCPL漏诊的风险,因此寻找有效识别CCPL的特异性分子标志物,具有重要临床意义。对具有序列相似性家族19成员A4(FAM19A4)基因启动子甲基化定量检测,可有效检出CCPL组织,较传统筛查方法有较高特异度,有望成为CCPL筛查的特异性分子标志物。笔者拟就FAM19A4基因启动子甲基化定量检测,在CCPL筛查中应用的最新研究现状进行阐述,旨在为进一步推进CCPL筛查方法的开发,提供思路。  相似文献   
96.
目的探讨中孕期胎儿染色体异常(FCA)高危孕妇羊水细胞胎儿染色体核型(FK)及其介入性产前诊断(IPD)指征。方法选择2014—2018年,在四川大学华西第二医院产前诊断中心进行羊膜腔穿刺术羊水细胞FK检测的63581例FCA高危孕妇(孕龄为19~27+6孕周)为研究对象。回顾性分析孕妇不同IPD指征及其胎儿染色体核型异常(FKA)检测结果。本研究遵循的程序符合四川大学华西第二医院伦理委员会所制定的伦理学标准,并通过该伦理委员会批准[审批文号:医学科研2019伦审批第(077)号]。结果①本组63581例中孕期孕妇的FKA检出率为3.13%(1989/63581)。这63581例孕妇的IPD指征分别为高龄(预产期年龄≥35岁)(25648例)、血清学筛查高风险(29009例)、无创产前筛查(NIPT)高风险(333例)、夫妇一方为染色体异常携带者(603例)、超声筛查发现胎儿结构异常及超声软指标异常(2647例)、异常儿生育史(1546例)、于外院进行羊水细胞FK分析结果异常者(7例)、孕妇智力低下及合并智力低下家族史(149例)、孕妇早孕期有害物质接触史(1400例)、其他(2239例),FKA检出率分别为3.26%(836/25648)、2.04%(593/29009)、65.17%(217/333)、34.33%(207/603)、3.51%(93/2647)、1.68%(26/1546)、85.71%(6/7)、4.03%(6/149)、0.14%(2/1400)、0.13%(3/2239)。②351例孕妇的IPD指征为超声筛查发现胎儿结构异常中,IPD指征为胎儿淋巴水囊瘤、皮肤水肿的FKA检出率最高,为26.09%(6/23)。2296例孕妇的IPD指征为胎儿超声软指标异常中,IPD指征为胎儿颈项透明层(NT)值≥2.5 mm的FKA检出率最高,为7.74%(66/853)。结论孕妇高龄、血清学筛查高风险、NIPT高风险、夫妇一方为染色体异常携带者、超声筛查发现胎儿结构异常及超声软指标异常等,均为中孕期孕妇FCA的IPD指征,孕妇IPD指征类型不同,FCA风险不同。羊膜腔穿刺术羊水细胞FK检测,可预测有IPD指征孕妇的妊娠结局,为降低FKA出生率提供参考。  相似文献   
97.
98.
目的 :以逆转录聚合酶链反应 (RT PCR)检测外周血大肠癌细胞 ,探讨大肠癌患者外周血中癌细胞存在的临床意义。方法 :应用RT PCR方法检测 47例不同Dukes分期结肠癌患者及其肝转移患者外周血中大肠癌细胞角蛋白 2 0 (CK2 0 ) ,并以大肠癌组织 (2 0例 )和正常健康人外周血 (2 0例 )为对照。结果 :正常健康人外周血中未见CK2 0mRNA表达 ,大肠癌患者外周血中CK2 0mRNA检出率达 40 4% (19/ 47) ,DukesB ,C ,D期患者外周血CK2 0mR NA检出率分别为 2 5 0 % (5 / 2 0 ) ,41 2 % (7/ 17)和 87 5 % (7/ 8) ,(P <0 0 5 )。肝转移患者CK2 0mRNA检出率为87 5 % (7/ 8) ,无肝转移患者检出率为 30 8% (12 / 39) (P <0 0 1)。结论 :CK2 0可作为肿瘤标志物 ,用于检测外周血中的大肠癌细胞 ,预测肿瘤复发及转移 ,识别高危患者  相似文献   
99.
目的研究22种肿瘤标志(TM)对诊断卵巢恶性肿瘤(OMN)的价值,选择最佳诊断标志群.方法用高压液相色谱法、自动生化仪检测法、酶联免疫法检测.结果单项TM的敏感性≥60%者分别为腐胺(100%)、精脒(84%)、CA125(80%)、唾液酸(SA)(70.4%)、铁蛋白(61.2%)、肿瘤特异生长因子(TS-GF)(60.9%)和CA153(60%).有效率≥80%者分别是TSGF(88.6%)、精胺(86.6%)、精脒(83.8%)、CA153(81.2%)、SA(81.1%)、腐胺(81.0%)和CA125(80%).最佳标志群为CA125、TSGF和SA.结论CA125是诊断OMN最敏感的TM,其次是SA、铁蛋白和TSGF.TM联合测定能提高诊断的有效性,其中以CA125、TSGF和SA联合测定效果较好.  相似文献   
100.
目的:观察干扰治疗慢性丙型肝炎过程中血清肝纤维化指标的改变。方法:应用ELISA法对44例慢性丙型肝炎病人在干扰素治疗开始时、结束时和停药后6个月检测血清透明质酸(HA)、层粘连蛋白(LN)、Ⅲ型前胶原肽(PⅢP)和Ⅳ型胶原(C-Ⅳ)。结果:干扰素治疗完全应答组(CR-S)和完全应答伴反跳组(CR-R)治疗前血清HA、LN、PⅢP和C-Ⅳ水平低于无应答组(NR)、差异显著(P<0.05);CR-S组干扰素治疗后血清HA、LN、PⅢP和C-Ⅳ水平明显下降(P<0.05);CR-R组和NR组干扰素治疗后血清肝纤维化指标无明显下降,甚至升高。结论:应用干扰素治疗丙型肝炎时,随着肝内炎症的改善,血清肝纤维化指标的水平明显下降,对慢性肝炎肝纤维化的发生和发展有改善作用。  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