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   23174篇
  免费   2172篇
  国内免费   1088篇
耳鼻咽喉   314篇
儿科学   329篇
妇产科学   307篇
基础医学   2276篇
口腔科学   381篇
临床医学   2922篇
内科学   2665篇
皮肤病学   475篇
神经病学   960篇
特种医学   873篇
外国民族医学   9篇
外科学   1461篇
综合类   4504篇
现状与发展   3篇
一般理论   2篇
预防医学   2284篇
眼科学   584篇
药学   2836篇
  53篇
中国医学   1715篇
肿瘤学   1481篇
  2024年   60篇
  2023年   303篇
  2022年   1077篇
  2021年   1468篇
  2020年   1126篇
  2019年   706篇
  2018年   799篇
  2017年   891篇
  2016年   726篇
  2015年   1255篇
  2014年   1543篇
  2013年   1562篇
  2012年   2320篇
  2011年   2339篇
  2010年   1597篇
  2009年   1345篇
  2008年   1398篇
  2007年   1232篇
  2006年   977篇
  2005年   786篇
  2004年   508篇
  2003年   413篇
  2002年   279篇
  2001年   220篇
  2000年   171篇
  1999年   114篇
  1998年   79篇
  1997年   76篇
  1996年   53篇
  1995年   70篇
  1994年   45篇
  1993年   44篇
  1992年   40篇
  1991年   51篇
  1990年   26篇
  1989年   30篇
  1988年   21篇
  1987年   19篇
  1986年   16篇
  1985年   22篇
  1984年   11篇
  1983年   13篇
  1982年   10篇
  1959年   50篇
  1958年   103篇
  1957年   107篇
  1956年   79篇
  1955年   82篇
  1954年   67篇
  1949年   10篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Vitamin H (biotin) was incorporated into a hydrophobically modified polysaccharide, pullulan acetate (PA), in order to improve the cancer-targeting activity and internalization of self-assembled nanoparticles. The biotinylated pullulan acetate (BPA) nanoparticles were prepared by a diafiltration method and the mean diameter was approximately 100 nm. Three samples of biotinylated pullulan acetate (BPA), comprising 7 (BPA 1), 20 (BPA 2), and 39 (BPA 3) vitamin H groups per 100 anhydroglucose units of PA, were synthesized. The critical aggregation concentrations (CAC) of the BPA nanoparticles in distilled water were 3.1 x 10(-3), 4.3 x 10(-3) and 6.8 x 10(-3) mg/ml for BPA 1, BPA 2, and BPA 3, respectively. Adriamycin (ADR) was loaded into the BPA nanoparticles as a model drug. The loading efficiencies and ADR content in the BPA nanoparticles decreased with increasing vitamin H content due to a lower hydrophobicity. The RITC-labeled BPA nanoparticles exhibited very strong adsorption to the HepG2 cells, while the RITC-labeled PA nanoparticles did not show any significant interaction. The degree of the interaction increased with increasing vitamin H content. Confocal laser microscopy also revealed that internalization of the BPA nanoparticles into the cancer cells depended on the vitamin H content.  相似文献   
32.
Seventy-eight patients (85 affected hips and 71 unaffected hips) with Legg-Calvé-Perthes disease were included in this study to evaluate the metaphyseal change in radiographs and magnetic resonance imaging (MRI) and to define the type of the metaphyseal cyst according to presence or absence of the epiphyseal involvement. The content of the metaphyseal cyst was evaluated by using T1,T2, proton, and gadolinium-enhanced T1-weighted MRI scans. Among 85 hips, there were no changes in 32 hips, marrow edema in 13 hips, false cyst with epiphyseal involvement in 28 hips, and true cyst without epiphyseal involvement in 12 hips. Granulation tissue was found in the false cysts and water-rich fibrotic tissue was found in the true cysts based on the MRI scans. The metaphyseal change in MRI scans was shown in 71% of groups 3 and 4 and in 35% of groups 1 and 2 according to the Catterall classification, and 52% of group A, 56% of group B, and 86% of group C according to the Herring classification. Of the 30 hips at the avascular stage, 33% showed metaphyseal cyst in MRI scans. Of the 53 hips at the fragmentation stage, 60% showed the metaphyseal cyst.  相似文献   
33.
Kim WG  Na MH  Kim JH 《Artificial organs》2000,24(9):729-733
An effective in vitro protocol for the investigation of thrombogenicity can provide many advantages in the development of mechanical circulatory assist devices. Strict avoidance of air contact with blood recently was proposed for reliable in vitro evaluation. This study was performed to confirm the necessity of avoidance of air contact for the in vitro test of thrombogenicity in a rotary pump. Two sets of mock circuits with the same rotary blood pumps, reservoirs, and connecting tubes were made. In one system, blood came in contact with air while the other did not. The test blood was heparinized at the dose of 1 IU per 1 ml of blood. The tests were terminated at an activated coagulation time of 1.5 times the control value. The levels of hematocrit, platelet, factors VIII and XII, fibrinogen, thromboxane B2, and plasma-free hemoglobin were measured during the procedures. After the experiments, the thrombi formed were observed, measured, and compared with those formed in in vivo circumstances. The tests were repeated 12 times. There were no statistically significant differences between the 2 groups in hematologic parameters and the amounts of thrombi formed. The thrombi observed in both groups showed the same pathologic findings as those formed in vivo with the exception of intermittent multiple air bubbles found in thrombi of the air-contact group. In conclusion, the effect of air contact in the in vitro investigation of thrombogenicity was negligible while the proposed in vitro test models of thrombogenesis in the mechanical circulatory assist device proved to be reliable.  相似文献   
34.
We assessed clinical results in 145 patients with chronic myeloid leukaemia in chronic phase who satisfied criteria for interferon-alpha failure and were thus eligible for treatment with imatinib at the Hammersmith Hospital. We used univariate and multivariate analyses to develop a risk score based on features defined after treatment for 3 months. We identified a low neutrophil count and poor cytogenetic response (<35% Ph-negative marrow metaphases) at 3 months as principal independent predictive factors and incorporated them into a three-tier prognostic scoring system for individual patients. For patients in the low-, intermediate- and high-risk groups, the probabilities of survival at 24 months were 100, 82 and 40% (P<0.0001) and progression-free survival 100, 66 and 15% (P<0.0001), respectively. This Hammersmith prognostic scoring system was validated with an independent cohort of patients treated at another UK centre.  相似文献   
35.
Objectives: To describe the physical growth patterns of infants born to narcotic dependent mothers (INDM) over a 12 months period and, if possible, to relate the growth to drug taking patterns during pregnancy.
Methodology: The growth of a cohort of 43 INDM was measured during the first 12 months of life. Weight and length measurements were compared with percentile charts and converted to Z scores. Questionnaire data about drug taking practices, demographic variables and the neonatal period (including withdrawal scores) were obtained.
Results: Twenty-four (55.8%) of INDM had evidence of neonatal drug withdrawal requiring treatment with phenobarbitone. At birth, Z scores for weight and length indicated relative intrauterine growth retardation. By 12 months, there had been some catch up growth, but Z scores for weight and length were still below zero. Persistent weight retardation at 12 months was correlated with methadone dosage during pregnancy, but not the need for phenobarbitone therapy.
Conclusions: The growth patterns of INDM in the first 12 months of life indicated that at birth there was evidence of intrauterine growth retardation, but by 12 months the growth was little different from the rest of the community. There appears to be some influence of narcotic agents taken while pregnant on subsequent growth of INDM.  相似文献   
36.
刺五加注射液治疗脑出血的临床评价   总被引:21,自引:0,他引:21  
吴岳洲  蔡鸿 《中医杂志》1998,39(4):213-214
30例高血压脑出血患者在常规疗法基础上加用紫外线辐射血液疗法作为对照组,另30例在上述疗法基础上加用刺五加注射液静脉滴注为治疗组。结果治疗组显效率96.7%,总有效率100%,对照组显效率60.0%,总有效率83.3%,治疗组明显优于对照组(P<0.01)。表明刺五加注射液不仅用于缺血性脑梗塞的治疗,而且也可用于脑出血,对出血量在30ml以下的病例,疗效较好。  相似文献   
37.
目的:探讨羟基喜树碱与肿瘤坏死因子相关凋亡诱导配体(tumor necrosis factor-related apoptosis inducing ligand,TRAIL)联用对肺腺癌A549细胞是否具有协同杀伤作用,并对其机制进行初步研究。方法:MTT法检测细胞毒性作用,流式细胞仪检测细胞凋亡和线粒体膜电位,Western blot分析bcl-2和bcl-xl蛋白水平变化。结果:单用100ng/mL TRAIL,4、40和400μg/mL羟基喜树碱对A549细胞杀伤率分别为13.9%、3.0%、23.4%和76.7%,联合用药的抑制率分别为43.6%、52.5%和83.1%。100ng/mL TRAIL和4μg/mL羟基喜树碱有协同作用,可使细胞线粒体膜电住降低,但不影响bcl-2和bcl-xl蛋白表达。结论:TRAIL与羟基喜树碱联用对肺腺癌A549细胞有明显的协同杀伤作用,其机制可能与羟基喜树碱降低A549细胞线粒体膜电位有关。  相似文献   
38.
目的:构建颈部三维有限元模型(finite element model,FEM),初步分析脊髓型颈椎病(cervical spondylotic myelopathy,CSM)患者与对照者颈部生物力学的差异,为CSM发病机制的研究提供生物力学依据。方法:以1名CSM患者作为力学模拟实验对象进行三维CT扫描,并构建颈部三维FEM依照患者的年龄、性别、身高、体重等参数选取本团队已有的健康颈部三维FEM作为对照,比较患者和对照者在颈椎正常受力情况下椎体、椎间盘、韧带及脊髓的应力差异,以及后仰伸运动后最大应力的差异。结果:成功构建CSM患者及对照者FEM模型,并进行力学分析,CSM患者颈椎椎体受力差异C5~C6节段最明显,对照者和患者的最大应力部位均在椎体前缘,CSM患者椎体前缘的最大应力小于对照者;CSM患者椎间盘应力分布不均匀,最大应力部位集中在椎间盘底部后缘的两侧;CSM患者各韧带的应力分布不均匀,其中后纵韧带应力最大。CSM患者颈椎在后仰伸运动时范围受限。结论:CSM患者相对于对照者可能存在颈部椎体、椎间盘及韧带受力平衡的改变和颈椎运动范围的受限,这可能与CSM力学发病机制相关。  相似文献   
39.
孙娜  袁雪梅 《循证护理》2022,(1):124-127
目的:探讨护理风险预警机制在慢性乙型肝炎肝衰竭病人护理中的应用效果。方法:选取2018年1月—2019年12月我院收治的104例慢性乙型肝炎肝衰竭病人,按照病人入院顺序,并采用单双号抽签方式分为对照组和观察组,各52例。对照组给予常规护理干预,观察组临床护理中引入护理风险预警机制,对比两组肝功能指标、并发症发生情况、护理满意度、护理质量评分、护理缺陷评分及住院时间。结果:干预后,两组肝功能指标均有所改善,且观察组下降幅度较对照组大(P<0.001);观察组与对照组并发症发生率分别为7.69%、25.00%,观察组与对照组总满意度分别为96.15%、76.92%,观察组病人护理质量评分高于对照组,护理缺陷评分及住院时间低于对照组,差异均有统计学意义(P<0.05)。结论:将护理风险预警机制用于慢性乙型肝炎肝衰竭病人的临床护理中,有利于改善病人肝功能指标,减少并发症及护理缺陷,提高护理满意度,提升护理质量,缩短病人住院时间。  相似文献   
40.
Although tacrolimus (TAC) has remarkable effects in ulcerative colitis (UC) patients when given as remission induction therapy, some can develop renal dysfunction during TAC administration, resulting in withdrawal, though related details remain poorly understood. This study was conducted to determine the impact of oral TAC on renal function for remission induction therapy in UC patients. Fifty-five patients (10 elderly, 45 non-elderly) with UC and treated with oral TAC at our hospital were retrospectively evaluated. Renal function was assessed using estimated glomerular filtration rate (eGFR). Although a high clinical response to TAC was seen in both elderly and non-elderly, a decline in eGFR was noted in nearly all patients regardless of age, with a maximum change of −34.4% from the baseline value at week 11. Furthermore, eGFR decline recovered quickly after TAC discontinuation, though did not return to the baseline at two years following cessation. The rate of eGFR change at week 12 was significantly associated with patient age (β = −0.3242, p = 0.0103) and peak serum trough level during TAC treatment (β = 0.3563, p = 0.0051). Furthermore, the rate of decline in eGFR was significantly greater during treatment with TAC in the elderly as compared to non-elderly, with a large difference in eGFR decline rate between those groups also noted at two years after withdrawal of treatment. Careful attention to renal function when administering oral TAC for UC is important and changes in eGFR should be monitored closely in elderly patients even after treatment cessation.  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