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   7931篇
  免费   902篇
  国内免费   144篇
耳鼻咽喉   51篇
儿科学   134篇
妇产科学   78篇
基础医学   825篇
口腔科学   78篇
临床医学   936篇
内科学   787篇
皮肤病学   33篇
神经病学   1656篇
特种医学   494篇
外科学   406篇
综合类   1198篇
一般理论   2篇
预防医学   828篇
眼科学   71篇
药学   762篇
  8篇
中国医学   485篇
肿瘤学   145篇
  2024年   13篇
  2023年   119篇
  2022年   207篇
  2021年   416篇
  2020年   397篇
  2019年   353篇
  2018年   320篇
  2017年   344篇
  2016年   328篇
  2015年   366篇
  2014年   606篇
  2013年   568篇
  2012年   477篇
  2011年   506篇
  2010年   384篇
  2009年   389篇
  2008年   342篇
  2007年   343篇
  2006年   332篇
  2005年   270篇
  2004年   222篇
  2003年   222篇
  2002年   167篇
  2001年   140篇
  2000年   103篇
  1999年   100篇
  1998年   68篇
  1997年   81篇
  1996年   47篇
  1995年   61篇
  1994年   63篇
  1993年   63篇
  1992年   43篇
  1991年   48篇
  1990年   61篇
  1989年   40篇
  1988年   40篇
  1987年   31篇
  1986年   33篇
  1985年   42篇
  1984年   40篇
  1983年   17篇
  1982年   26篇
  1981年   20篇
  1980年   30篇
  1979年   16篇
  1978年   16篇
  1977年   23篇
  1975年   8篇
  1973年   7篇
排序方式: 共有8977条查询结果,搜索用时 15 毫秒
41.
The purpose of this study was to examine the effect of exacerbations on mild to moderate asthmatic patients' preference-based, health-related, quality of life scores and also to describe the effect of these exacerbations on daily life. In a survey, 100 mild to moderate asthmatic patients in the United Kingdom were asked to rate three different health marker states on a scale between 0 (death) and 100 (perfect health), defined as: your asthma of today, a mild exacerbation, and a severe exacerbation of asthma. They were also asked to describe their symptoms and what they did when experiencing an exacerbation. During exacerbations the vast majority of asthmatic patients have significant symptoms and consume a considerable amount of health care resources, which often overlap. The health marker state “your asthma of today” was given a mean score of 81.0, a mild exacerbation a score of 62.1, and a severe exacerbation a score of 25.6, indicating a large impact on patients' daily life and their health-related quality of life. In conclusion, asthmatic patients are severely affected in their health and daily living by mild and severe exacerbations. Considerable effort should be made to reduce the number and severity of exacerbations.  相似文献   
42.
EVOKED POTENTIALS OF OBSESSIVE-COMPULSIVE DISORDER: STATE OR TRAIT MARKER   总被引:1,自引:0,他引:1  
Objective To investigate the status of evoked potentials in obsessive-compulsive disorder(OCD). Methods Evoked potentials P300, auditory brainstem response (ABR) and visual evoked potential ( VEP) were recorded from 35 OCD patients and 28 normal controls (NC) with a Nicolet Spirit Instrument. 23 of the OCD patients were followed up after 5 months with the same markers. Results Compared with NC, OCD patients showed decreased P3 of P300 amplitude (OCD group 3. 5 ±1. 6μv vs. NC group 5.9 ±2. 1μv, P <0. 01), delayed V latency (6.4±0. 4ms vs. 5. 5 ±0. 3ms, P <0. 01) and increased V amplitude(0. 35±0. 1μv vs. 0. 16 ±0.09μv, P <0. 05) of ABR and delayed P2 of VEP latency (199±39ms vs. 183±28ms, P <0. 05). The follow-up measures of evoked potentials suggested that decreased P3 of P300 amplitude and delayed P2 of VEP latency might be state markers of OCD, while decreased V amplitude and delayed V of ABR latency might be trait markers of OCD. Conclusion The changes of P300 and VEP are related to clini  相似文献   
43.
This work describes a new approach to multipoint Dixon fat-water separation that is amenable to pulse sequences that require short echo time (TE) increments, such as steady-state free precession (SSFP) and fast spin-echo (FSE) imaging. Using an iterative linear least-squares method that decomposes water and fat images from source images acquired at short TE increments, images with a high signal-to-noise ratio (SNR) and uniform separation of water and fat are obtained. This algorithm extends to multicoil reconstruction with minimal additional complexity. Examples of single- and multicoil fat-water decompositions are shown from source images acquired at both 1.5T and 3.0T. Examples in the knee, ankle, pelvis, abdomen, and heart are shown, using FSE, SSFP, and spoiled gradient-echo (SPGR) pulse sequences. The algorithm was applied to systems with multiple chemical species, and an example of water-fat-silicone separation is shown. An analysis of the noise performance of this method is described, and methods to improve noise performance through multicoil acquisition and field map smoothing are discussed.  相似文献   
44.
抗凝治疗肺心病血栓前状态的临床研究   总被引:6,自引:2,他引:4  
目的探讨肺心病患者的血栓前状态,观察并分析低分子肝素抗凝干预的疗效。方法将54倒肺心病患者分为低分子肝素治疗组和常规治疗组各27例。分别检测治疗前后血浆血管性假血友病因子(VWF)、血浆凝血酶片段1 2(F1 2)、纤堆蛋白原(Fg)、血小板颗粒膜蛋白(GMP-140)和D-二聚体(DD)。结果肺心病患者VWF、F1 2、Fg、GMP-140、DD血浆浓度显著高于对照组;肺心病治疗组经LMWH治疗后上述各凝血分子标记物及PaCO2明显降低。而PaO2显著增高。常规组虽血气指标略有改善。但凝血分子标记物未见改善。结论尽早检测肺心病血栓前状态,及时给予低分子肝素抗凝干预,有望从根本上改善肺心病惠性加重期患者的不良预后。  相似文献   
45.
对一个脆性X染色体阳性家系进行了调查,用缺叶酸培养基(TC199)检查2名患者,脆性X检出率分别为13%,19%,本家系内尚有1名男性携带者,提示该家系脆性X染色体综合征不属于典型的X连锁隐性遗传。  相似文献   
46.
Based on the fuzzy characteristic of the pulse state and syndromes differentiation thinking mode of TCM, an information fusing recognition method of pulse states based on SFNN (Stochastic Fuzzy Neural Network) is presented in this paper. With the learning ability in parameters and structure, SFNN fuses the measurement information of three pulse-state sensors distributed in Cun, Guan, and Chi location of body for the pulse state recognition. The experimental results show that the percentage of correct recognition with new method is higher than that by single-data recognition one, with fewer off-line train numbers.  相似文献   
47.
皮肤病患者焦虑水平评估及对策   总被引:1,自引:0,他引:1  
陈晓霞  代喆  江雪梅  蒲晓英 《西部医学》2009,21(7):1230-1231
目的正确评估皮肤疾病患者的焦虑水平,为制定有针对性的护理对策提供依据。方法对136例皮肤病患者采用状态-特质量表(STAI-FormY)进行心理状态评估。结果133例患者状态焦虑阳性47例,总阳性率35%,其中神经性皮炎阳性数23例,阳性率59%(23/39),天疤疮阳性数7例,阳性率58%(7/12),慢性荨麻疹阳性数8例,阳性率53%(8/15),湿疹阳性数2例,阳性率20%(2/10),带状疱疹阳性数5例,阳性率14%(5/36),过敏性紫癜阳性数2例,阳性率12%(2/16)。患者总体状态与特质焦虑评分相关性分析显示两者之间关系密切,呈直线正相关关系(r=0.81,P〈0.001)。结论住院皮肤疾病患者存在较多的焦虑状态,通过量表评估患者的焦虑程度,能较准确的找出焦虑者。  相似文献   
48.
Investigators often study rats by microCT to investigate the pathogenesis and treatment of skeletal disorders in humans. However, microCT measurements provide information only on bone mineral content and not the solid matrix. CT scans are often carried out on cancellous bone, which contains a significant volume of marrow cells, stroma, water, and fat, and thus the apparent bone mineral density (BMD) does not reflect the mineral density within the matrix, where the mineral crystals are localized. Water- and fat-suppressed solid-state proton projection imaging (WASPI) was utilized in this study to image the solid matrix content (collagen, tightly bound water, and other immobile molecules) of rat femur specimens, and meet the challenges of small sample size and demanding submillimeter resolution. A method is introduced to recover the central region of k-space, which is always lost in the receiver dead time when free induction decays (FIDs) are acquired. With this approach, points near the k-space origin are sampled under a small number of radial projections at reduced gradient strength. The typical scan time for the current WASPI experiments was 2 hr. Proton solid-matrix images of rat femurs with 0.4-mm resolution and 12-mm field of view (FOV) were obtained. This method provides a noninvasive means of studying bone matrix in small animals.  相似文献   
49.
目的通过蛇毒抗高凝状态酶(AHCSE)、氟尿嘧啶(5-FU)对人肝癌细胞BEL-7404(简称7404细胞)、正常LO2肝细胞(简称LO2细胞)作用的比较,研究AHCSE对肝癌的作用以及探讨其可能的作用机制。方法应用光学显微镜、透射电镜、MTT法、TUNEL、FCM等方法观察7404细胞、LO2细胞经过AHCSE、5-FU处理后,细胞形态学、生物化学等方面的变化。结果7404细胞、LO2细胞经过AHCSE、52FU处理后,发生了形态学改变;小剂量AHCSE对7404细胞具有很强的抑制作用,但对LO2细胞几乎无影响;随着剂量的加大,AHCSE对7404细胞抑制率上升不明显,但是出现对LO2细胞的抑制作用。经AHCSE作用后,7404细胞发生了凋亡,凋亡率随AHCSE浓度的增加而增加;与5-FU对7404细胞作用相似,但5-FU对LO2细胞抑制作用明显增强。结论AHCSE、5-FU对BEL-7404细胞均有很强的抑制作用,诱导细胞凋亡是其作用机制之一,AHCSE可能成为一种新的肝癌细胞凋亡的诱导剂。  相似文献   
50.
目的 观察七氟醚或丙泊酚麻醉时脑状态指数(CSI)的变化.方法 30例腹腔镜手术患者随机均分成七氟醚组(S组)和丙泊酚组(P组).麻醉诱导:S组吸入2%的七氟醚,每隔1分钟增加1%;P组每隔1分钟重复给予15 mg丙泊酚,直至患者意识消失.记录患者诱导期的CSI数值,并对患者的镇静程度采用警觉/镇静评分(OAA/S)标准评分.结果 S组与P组术前CSI基础值差异无统计学意义,随着麻醉的加深,两组的CSI数值均明显下降(P<0.01),至OAA/S 1分时S组与P组的CSI数值较OAA/S 5分时明显下降(P<0.05或P<0.01),S组与P组的CSI与OAA/S的相关系数r分别为0.843和0.812.结论 CSI监测可反映七氟醚或丙泊酚麻醉时的麻醉深度.  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