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   15249篇
  免费   1520篇
  国内免费   1174篇
耳鼻咽喉   85篇
儿科学   184篇
妇产科学   179篇
基础医学   1855篇
口腔科学   279篇
临床医学   2163篇
内科学   2369篇
皮肤病学   141篇
神经病学   866篇
特种医学   628篇
外国民族医学   13篇
外科学   1322篇
综合类   2584篇
现状与发展   4篇
一般理论   3篇
预防医学   928篇
眼科学   375篇
药学   1576篇
  20篇
中国医学   991篇
肿瘤学   1378篇
  2024年   55篇
  2023年   279篇
  2022年   667篇
  2021年   856篇
  2020年   629篇
  2019年   579篇
  2018年   600篇
  2017年   529篇
  2016年   466篇
  2015年   707篇
  2014年   906篇
  2013年   750篇
  2012年   1091篇
  2011年   1227篇
  2010年   779篇
  2009年   614篇
  2008年   831篇
  2007年   740篇
  2006年   744篇
  2005年   744篇
  2004年   517篇
  2003年   497篇
  2002年   426篇
  2001年   350篇
  2000年   377篇
  1999年   355篇
  1998年   201篇
  1997年   204篇
  1996年   185篇
  1995年   164篇
  1994年   144篇
  1993年   102篇
  1992年   107篇
  1991年   71篇
  1990年   89篇
  1989年   60篇
  1988年   46篇
  1987年   54篇
  1986年   38篇
  1985年   34篇
  1984年   30篇
  1983年   25篇
  1982年   9篇
  1981年   5篇
  1978年   4篇
  1976年   5篇
  1975年   7篇
  1973年   8篇
  1972年   4篇
  1968年   6篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
51.
As part of a Hastings Center Report series of six articles on reproductive technologies around the world, three Japanese scholars report on the situation in their country. At present, artificial insemination and in vitro fertilization are offered to infertile married couples, and research is performed on early embryos up to 14 days after fertilization. Neither surrogate mothers nor donated gametes are used in Japan. Bai, Shirai, and Ishii identify several issues that they believe merit further public debate, among them the legal status of AID children, the experimental nature of in vitro fertilization, genetic manipulation of embryos, and gender selection. They summarize the findings of four opinion surveys that show a lack of consensus among the Japanese on the acceptability of reproductive technologies, which in the words of the authors "create a tension and a link between traditional belief and contemporary practice."  相似文献   
52.
53.
目的:评价京尼平交联治疗兔大泡性角膜病变的效果.方法:将已建立大泡性角膜病变动物模型的9只雌性新西兰白兔随机分为3组:治疗组(n=3),对照组(n=3),空白对照组(n=3).其中治疗组:刮除角膜上皮后,应用0.25%的京尼平浸泡实验眼角膜40min(24℃);对照组:刮除角膜上皮后,应用生理盐水浸泡实验眼角膜40min(24℃);空白对照组:不进行任何处理.处理后2wk内进行以下检查:裂隙灯检查、中央角膜厚度(CCT)测量、体质量和应激反应评估、组织学检查和利用原位末端转移酶标记技术(TUNEL法)检测基质层细胞凋亡.结果:与对照组和空白对照组相比,治疗组角膜水肿明显减轻、角膜上皮逐渐修复完整、角膜大泡消失、中央角膜角膜厚度显著下降(P<0.05)、体质量显著增加(P<0.05).治疗组的实验动物活动性较处理前增加,反抗行为减少,攻击性减低.治疗组角膜基质层胶原纤维排列更为紧致、规则,可见蓝色条索状交联产物.治疗组角膜基质层均偶见凋亡细胞,对照组及空白对照组未明显见凋亡细胞.结论:京尼平交联治疗可使兔大泡性角膜病变角膜水肿减轻,疼痛症状缓解,其可能的机制为京尼平交联使角膜基质层胶原纤维排列紧密,从而阻止角膜水肿和大泡的形成.  相似文献   
54.
Background: The role of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children with high-risk (HR) T-cell acute lymphoblastic leukemia (T-ALL) in first complete remission (CR1) is still under evaluation. Moreover, relapse is the main factor affecting survival. This study aimed to explore the effect of allo-HSCT (especially haploidentical HSCT [haplo-HSCT]) on improving survival and reducing relapse for HR childhood T-ALL in CR1 and the prognostic factors of childhood T-ALL in...  相似文献   
55.
背景 目前,药物疗法是失眠障碍的一线治疗手段,但仍然存在着一定的不良反应。与药物治疗相比,重复经颅磁刺激(rTMS)和失眠的认知行为治疗(CBT-I)的不良反应较少、患者耐受性较好。目的 探讨rTMS与CBT-I治疗慢性失眠障碍的效果,以期为慢性失眠障碍患者提供更优的治疗方案。方法 选取2020年9月21日—2021年12月16日在内蒙古自治区精神卫生中心门诊或社区医院就诊的、符合《国际睡眠障碍分类第三版》(ICSD-3)诊断标准的慢性失眠障碍患者(n=50),同期在社区招募与患者组年龄和性别相匹配的健康人作为对照组(n=16)。采用随机数字表法将慢性失眠障碍患者分为rTMS组与CBT-I组各25例,分别接受为期6周的rTMS或CBT-I干预。于干预前和干预后,慢性失眠障碍患者接受多导睡眠监测(PSG)以及匹兹堡睡眠质量指数量表(PSQI)、失眠严重程度指数量表(ISI)、重复性成套神经心理状态测验(RBANS)评定。对患者组和对照组进行静息态磁共振成像(rs-fMRI)扫描,并进行静息态低频振幅(ALFF)分析。将患者组和对照组ALFF值差异有统计学意义的脑区作为感兴趣区域(ROI),将其作为种子点与患者全脑进行功能连接分析。结果 rTMS组和CBT-I组的PSQI评分、ISI评分以及RBANS中的即刻记忆、言语功能、延时记忆维度评分的时间效应均有统计学意义(F=41.160、69.615、47.923、12.090、28.193,P均<0.05);两组总睡眠时间的时间效应、睡眠效率的时间效应和组别效应以及N1%的时间效应均有统计学意义(F=8.995、12.414、4.342、7.806,P均<0.05)。干预后,CBT-I组睡眠效率高于干预前(t=-2.785,P<0.05)。rTMS组眶部额上回与左侧豆状壳核(t=4.991,P<0.05)、右内侧和旁扣带回(t=4.471,P<0.05)和右侧中央后回(t=4.922,P<0.05)之间的功能连接增强,CBT-I组眶部额上回与左侧额中回之间的功能连接增强(t=6.586,P<0.05)。结论 rTMS及CBT-I可能有助于改善慢性失眠障碍患者的失眠情况和认知功能。  相似文献   
56.
The treatment of nonalcoholic fatty liver disease (NAFLD) remains very challenging. This study investigated the therapeutic effect of galactose oligosaccharide (GOS), an important prebiotic, on NAFLD through in vivo and in vitro experiments and preliminarily explored the mechanism by which GOS improves liver lipid metabolism and inflammation through liver and intestinal microbiological analysis. The results of mouse liver lipidomics showed that GOS could promote body thermogenesis in mice with high-fat and high-sugar diet (HFHSD)-induced NAFLD, regulate lipolysis in liver fat cells, and accelerate glycine and cholesterol metabolism. GOS dose-dependently reduced the contents of total cholesterol (TC) and triglyceride (TG) in cells and reduced the accumulation of lipid droplets in cells. GOS also reduced the Firmicutes/Bacteroidetes ratio and altered the composition of the intestinal microbiota in mice fed a HFHSD. GOS can improve liver lipid metabolism and intestinal structure of NAFLD. These results provide a theoretical and experimental basis supporting the use of GOS as a health food with anti-NAFLD functions.  相似文献   
57.
Freeze–thaw damage is one of the most severe threats to the long-term performance of concrete pavement in cold regions. Currently, the freeze–thaw deterioration mechanism of concrete pavement has not been fully understood. This study summarizes the significant findings of concrete pavement freeze–thaw durability performance, identifies existing knowledge gaps, and proposes future research needs. The concrete material deterioration mechanism under freeze–thaw cycles is first critically reviewed. Current deterioration theories mainly include the hydrostatic pressure hypothesis, osmolarity, and salt crystallization pressure hypothesis. The critical saturation degree has been proposed to depict the influence of internal saturation on freeze–thaw damage development. Meanwhile, the influence of pore solution salinity on freeze–thaw damage level has not been widely investigated. Additionally, the deterioration mechanism of the typical D-cracking that occurs in concrete pavement has not been fully understood. Following this, we investigate the coupling effect between freeze–thaw and other loading or environmental factors. It is found that external loading can accelerate the development of freeze–thaw damage, and the acceleration becomes more evident under higher stress levels. Further, deicing salts can interact with concrete during freeze–thaw cycles, generating internal pores or leading to crystalline expansion pressure. Specifically, freeze–thaw development can be mitigated under relatively low ion concentration due to increased frozen points. The interactive mechanism between external loading, environmental ions, and freeze–thaw cycles has not been fully understood. Finally, the mitigation protocols to enhance frost resistance of concrete pavement are reviewed. Besides the widely used air-entraining process, the freeze–thaw durability of concrete can also be enhanced by using fiber reinforcement, pozzolanic materials, surface strengthening, Super Absorbent Polymers (SAPs), and Phase Change Materials. This study serves as a solid base of information to understand how to enhance the freeze–thaw durability of concrete pavement.  相似文献   
58.
目的探讨本地区泌尿系结石疾病患者利用泌尿系结石红外光线自动分析仪分析的结石成分构成及其临床意义。方法回顾性分析我院2014年5月至2020年5月3760例泌尿系结石疾病患者资料,采用泌尿系结石红外光线自动分析仪(LIIR-20型)分析结石成分组成。结果泌尿系结石以肾结石为主(2932例,77.98%)。从结石成分看,草酸钙结石最常见2999例(79.76%)、其次分别是无水尿酸结石229例(6.09%)、碳酸磷灰石187例(4.97%)。从性别来看,男性泌尿系结石发病率明显高于女性[男2659例(70.72%),女1101例(29.28%)],其中男性一水草酸钙结石较女性明显多发(男71.86%,2155/2999;女28.14%,844/2999),女性六水磷酸铵镁类感染性结石明显多于男性(男36.36%,52/143;女63.64%,91/143)。从年龄上看,成年患者多表现为一水草酸钙结石,而小儿患者(10岁及以下)多表现为尿酸胺(30.43%,56/184)及胱氨酸结石(3.80%,7/184)。结论本医疗中心泌尿系结石成分以草酸钙类结石为主,存在着年龄及性别等的差异;泌尿系结石红外光线自动分析仪作为新技术可以很好地分析泌尿系结石成分,为针对结石成分的特点采取相应的预防和诊疗措施提供了依据。  相似文献   
59.
A simple renal cyst (SRC) may increase the risk for hypertension. The authors examined the relationship between a SRC and hypertension in participants receiving physical examinations at Hebei Medical University. This study enrolled 66 883 participants who received physical examinations at our center from January 2012 to December 2017. Demographic data, medical history related to hypertension, hematological indexes, hypertension, and SRC subtype based on ultrasound examinations were examined. The relationship between SRC and hypertension was analyzed using univariate and multivariate logistic regression analysis in different models. Subgroup analysis and propensity score (PS) matching were also performed. Based on SRC subtype (unitary vs. multiple, small vs. large, unilateral vs. bilateral), a comprehensive scoring system was established to determine the effect of SRC load on hypertension. The results of univariate and multivariate analysis indicated that SRC was a risk factor for hypertension (< .01). Subgroup and interaction analysis showed the homogeneity that SRC was an independent risk factor for hypertension in multiple subgroups (P > .05). A SRC remained an independent risk factor for hypertension after PS matching (P < .01). Based on a scoring system that considered different SRC subtypes, the risk for hypertension increased with renal cyst load (< .01). In conclusions, a SRC was an independent risk factor for hypertension, and there was a positive correlation between SRC load and hypertension. The risk of hypertension increased gradually with the size, number, and location of a SRC. Careful follow‐up or excision should be considered for patients with SRCs.  相似文献   
60.
Objectives:Leiomyosarcoma of inferior vena cava (IVC) is a rare clinical entity with severe vascular involvement. Surgical management of leiomyosarcoma is still challenging.Methods:This a retrospective study of consecutive patients referred to our hospital from January 2017 to June 2019. Depending on the anatomical site of affected IVC, leiomyosarcomas were categorized into zone I-II. The clinical data including baseline information, surgical parameters, peri-operative management, short- and mid-term outcomes were observed.Results:Four patients with leiomyosarcoma of zone I-III underwent radical resection without intraoperative mortality. Prosthetic grafts were interpositioned in all patients to instruct vena cava. Renal vein reconstruction was perfumed in two patients due to involvement to renal veins. Median blood loss was 450 mL (200–600 mL), median operative time was 215 minutes (150–240 minutes). No Clavien-Dindo IIIa or higher complication was observed. No organ dysfunction and recurrence were observed with median follow-up of 25.5 months.Conclusions:Curative resection of zone I-II leiomyosarcoma is associated with longer survival in selected cases, en-bloc resection with complex vascular reconstruction could be considered.  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