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   17174篇
  免费   1626篇
  国内免费   1448篇
耳鼻咽喉   75篇
儿科学   78篇
妇产科学   47篇
基础医学   2013篇
口腔科学   367篇
临床医学   897篇
内科学   2009篇
皮肤病学   370篇
神经病学   681篇
特种医学   697篇
外科学   576篇
综合类   2557篇
一般理论   1篇
预防医学   1422篇
眼科学   226篇
药学   4627篇
  11篇
中国医学   3290篇
肿瘤学   304篇
  2024年   30篇
  2023年   271篇
  2022年   390篇
  2021年   725篇
  2020年   601篇
  2019年   473篇
  2018年   424篇
  2017年   579篇
  2016年   618篇
  2015年   731篇
  2014年   1090篇
  2013年   1394篇
  2012年   1138篇
  2011年   1258篇
  2010年   993篇
  2009年   965篇
  2008年   1012篇
  2007年   854篇
  2006年   841篇
  2005年   760篇
  2004年   594篇
  2003年   551篇
  2002年   441篇
  2001年   420篇
  2000年   309篇
  1999年   307篇
  1998年   256篇
  1997年   198篇
  1996年   208篇
  1995年   171篇
  1994年   178篇
  1993年   160篇
  1992年   161篇
  1991年   136篇
  1990年   114篇
  1989年   114篇
  1988年   112篇
  1987年   99篇
  1986年   84篇
  1985年   83篇
  1984年   75篇
  1983年   65篇
  1982年   59篇
  1981年   40篇
  1980年   44篇
  1979年   34篇
  1978年   26篇
  1977年   17篇
  1976年   17篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
目前在中医界已发布的冠心病痰湿证辨证标准是以主症、次症形式定性地给出,存在主观性较强的问题。本文引入约束隐结构分析,该方法将主症、次症的语义作为约束条件加入隐结构分析过程,得到含有主症、次症语义约束的定量化中医证候辨证规则。使用该方法对冠心病痰湿证患者556条无标签数据的分析,得到其约束隐结构模型,最后建立定量化痰湿证辨证规则,舌胖边有齿痕(3.16)、苔腻(3.12)、苔白滑(4.72)、胸闷(1.73)、脉濡或滑(6.04);次症:肢体困重(0.48)、口黏(0.63)、体胖(0.49)、大便粘滞(1.38)、脘腹痞满(0.97)、面色晦浊(0.79)、嗜睡(1.18)、纳差(1.07)。与经典隐结构模型得到规则和中医界已发布的定性化辨证规则相比,约束隐结构得到的规则客观性强,具有可重复性。在证候类大小、规则的量化合理度上较好地反映了主症、次症的特点,得到的规则切合中医实际,为冠心病痰湿证辨证标准的定量化研究提供帮助和参考。  相似文献   
3.
Intervertebral disc disease (IVDD) is a common musculoskeletal disease affecting about 5% of all individuals. It is characterized by lumbar disc herniation, which causes nerve root irritation, either mechanically or via inflammatory mediators, and results in radiating pain, known as sciatica. Numerous studies have been conducted to identify the causes and risk factors for IVDD. Lifting heavy loads, torsional stress, and motor vehicle driving are among the best-identified environmental risk factors. However, it has become evident recently from family and twin studies that genetic factors may also be important in IVDD. This hypothesis was strengthened by the identification of two collagen IX alleles associated with sciatica and lumbar disc herniation. In addition, disc degeneration has been shown to be related to an aggrecan gene polymorphism, a Vitamin D receptor and matrix metalloproteinase-3 gene alleles. This review highlights the genetic role and occupational aspects of IVDD.  相似文献   
4.
Researchers continue to lament the lack of organisational focus in the sociology of health and illness. Although studies have increasingly focused on boundaries between organizations, little such research has focused on the formal boundaries within the hospital itself. Given its dramatic compartmentalisation, and continuing prevalence in health systems, the lack of organisational perspective in hospital research limits insights into the effects (as well as the construction) of the order of health work and care. With a greater emphasis on ‘ordering’ in the concept of negotiated order, the aim of this study is to examine the manifestation and consequences of the formal boundaries of hospital departments. Fieldwork featured 12 months of ethnography, including formal and informal observations, 80 audio‐recorded, semi‐structured interviews, and 56 field interviews, in the Emergency Departments (EDs) of two tertiary referral hospitals. Compared with in‐patient hospital departments, the ED has limited legitimacy claims of organ‐specific knowledge to transfer patients out of the ED. The manifestation of specialised knowledge hierarchies in organisational structures disadvantages patients who are older and who have chronic conditions, underpinning the argument that effects as well as the negotiation of stable organisational orders deserve increased attention in the sociology of health and illness.  相似文献   
5.
6.
7.
目的 探讨以行为-结构化-关系(BSR)干预模式对短期住院孤独症谱系障碍(ASD)儿童的干预疗效,为改善ASD儿童的预后提供参考依据。方法 选取2015年12月-2016年12月确诊为ASD的2~6岁儿童141例,随机分为治疗组和对照组。治疗组ASD儿童均接受BSR模式的短期课程训练,训练课程包括个别辅导、游戏课、运动课、音乐课等,每天训练时间6 h,持续1个月;对照组ASD儿童处于干预等待,接受随访观察和评估。所有ASD儿童干预前、后均接受儿童心理教育评估(第三版)(PEP-3)来进行各方面能力变化的评估。结果 治疗组、对照组干预前各副测验的原积分差异无统计学意义(P>0.05)。两组ASD儿童干预后认知、语言理解、模仿、情感表达、社会互动、行为特征-非语言、适应行为的原积分比较,差异均有统计学意义(t=2.41、2.02、4.14、3.69、4.42、2.69、2.96,P<0.05);但小肌肉、大肌肉、自理的原积分比较,差异无统计学意义(t=-1.13、-1.05、-0.84,P>0.05)。结论 BSR干预模式能够有效改善短期住院ASD儿童的预后,可推广用于儿童ASD的治疗。  相似文献   
8.
Steady-state axisymmetric simulations using the Reynolds-Averaged Navier-Stokes equations have been carried out in order to optimize the performance of a Chemical, Biological, Radiological, and Nuclear (CBRN) canister filter for its use in a powered air-purifying respirator (PAPR). Alterations have been made to the shape of the canister, the spacing of the rear wall of the canister with regard to the carbon filter, and the bracketing between (i) the particulate filter and the carbon bed and (ii) the carbon bed and the canister wall. The pressure drops across the canister and the residence time distribution at the rear of the carbon bed have been analyzed in detail based on an extensive parametric analysis involving the aforementioned variations. It has been demonstrated that the non-uniform porosity profile of the carbon bed resulted in alternating regions of high and low velocity close to the canister wall, providing a possible route for breakthrough. Designs, which included a bracket at the rear of the carbon bed, blocked this route and consequently had a longer minimum mean residence time than those, which did not. It has also been shown that the spacing between the carbon bed and the canister rear wall had a large impact on both residence time and pressure drop. In cases where the carbon backed directly onto the canister rear wall flow in the axial direction from the outside wall toward the canister axis resulted in far greater pressure drop and a reduction in minimum mean residence time within the carbon bed.  相似文献   
9.
The purpose of this study was to compare acoustic structure quantification (ASQ) with transient elastography for staging liver fibrosis. One hundred eighty-two patients with chronic hepatitis B and without moderate to severe hepatic steatosis scheduled for liver biopsy underwent ASQ and transient elastography examinations. All ASQ parameters, including total mode, total average, red mode, red average, red standard deviation, blue mode, blue average, blue standard deviation and focal disturbance (FD) ratio and liver stiffness obtained via transient elastography were found to correlate with fibrosis stage (Spearman's r?=?0.783, 0.791, 0.750, 0.771, 0.544, 0.718, 0.691, 0.439, 0.815 and 0.814, respectively; all p values < 0.001). Among the ASQ parameters, the FD ratio had the highest correlation with the stage of fibrosis. The areas under the receiver operating characteristic curves (AUCs) of FD ratio and liver stiffness were 0.911 and 0.906 for F ≥ F1, 0.918 and 0.882 for F ≥ F2, 0.911 and 0.914 for F ≥ F3 and 0.926 and 0.978 for F?=?F4, respectively. There was no significant difference in AUCs between FD ratio and liver stiffness in predicting different stages of fibrosis (p?=?0.062–0.912). ASQ is a promising technique for assessing liver fibrosis in the absence of moderate to severe hepatic steatosis.  相似文献   
10.
Cocrystallization and salt formation were used to produce new multicomponent forms of a novel antimalarial imidazopyridazine drug lead (MMV652103) that displayed improved physicochemical properties. The drug lead had earlier shown good in vitro potency against multidrug resistant (K1) and sensitive (NF54) strains of the human malaria parasite Plasmodium falciparum, and high in vivo efficacy in both Plasmodium berghei and Plasmodium falciparum mouse models. A major drawback of MMV652103 is its limited aqueous solubility. Various new supramolecular products, including several multicomponent solid forms, are reported here, namely 3 cocrystal forms with the dicarboxylic acid coformers adipic acid, glutaric acid, and fumaric acid, and a salt form with malonic acid. These were characterized by thermal methods and their structures elucidated by single-crystal X-ray diffraction. A customized solubility experiment was performed in fasted-state simulated intestinal fluid for comparison of the solubility behavior of each new form of the drug lead with that of the untreated starting material. All of the multicomponent forms showed an improvement in the maximum concentrations (Cmax) attained by the drug lead and the rate at which it dissolved. The recorded Cmax values exceeded the concentration of the untreated compound by factors in the range 4.6-5.6.  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