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   19235篇
  免费   2098篇
  国内免费   1619篇
耳鼻咽喉   93篇
儿科学   237篇
妇产科学   147篇
基础医学   1886篇
口腔科学   362篇
临床医学   2476篇
内科学   2578篇
皮肤病学   219篇
神经病学   1060篇
特种医学   933篇
外国民族医学   6篇
外科学   2261篇
综合类   3730篇
现状与发展   2篇
一般理论   1篇
预防医学   1432篇
眼科学   482篇
药学   2166篇
  11篇
中国医学   1432篇
肿瘤学   1438篇
  2024年   69篇
  2023年   296篇
  2022年   702篇
  2021年   820篇
  2020年   709篇
  2019年   685篇
  2018年   637篇
  2017年   617篇
  2016年   644篇
  2015年   908篇
  2014年   1093篇
  2013年   1096篇
  2012年   1459篇
  2011年   1629篇
  2010年   1166篇
  2009年   1016篇
  2008年   1135篇
  2007年   1208篇
  2006年   963篇
  2005年   851篇
  2004年   779篇
  2003年   867篇
  2002年   823篇
  2001年   610篇
  2000年   484篇
  1999年   349篇
  1998年   219篇
  1997年   188篇
  1996年   167篇
  1995年   119篇
  1994年   105篇
  1993年   76篇
  1992年   79篇
  1991年   77篇
  1990年   68篇
  1989年   52篇
  1988年   52篇
  1987年   39篇
  1986年   30篇
  1985年   19篇
  1984年   16篇
  1983年   6篇
  1982年   6篇
  1979年   6篇
  1977年   2篇
  1976年   3篇
  1975年   1篇
  1972年   1篇
  1971年   3篇
  1932年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
目的:为人颅底的生长发育研究提供正常的颅底结构测量数据和参照标准;初步分析颅底生长发育趋势和特点。方法:对人不同生长发育阶段颅底标本诸结构进行观察和测量,并对其进行相互比较和纵向分析。结果:颅底在不同发育阶段各有其趋势和特点,蝶枕角随着年龄的增长逐渐变小,但性别之间无差异,颅前窝诸结构变化幅度最大,颅中窝的变化相对最小,11项测量指标在不同生长发育阶段的变化各异。结论:观察测量数据可为人颅底生长发育进一步研究提供依据,蝶枕角、耳眼(FH)平面可作为颅底生长发育的观察测量指标和参照平面。  相似文献   
92.
In parallel imaging, the signal‐to‐noise ratio (SNR) of sensitivity encoding (SENSE) reconstruction is usually degraded by the ill‐conditioning problem, which becomes especially serious at large acceleration factors. Existing regularization methods have been shown to alleviate the problem. However, they usually suffer from image artifacts at high acceleration factors due to the large data inconsistency resulting from heavy regularization. In this paper, we propose Bregman iteration for SENSE regularization. Unlike the existing regularization methods where the regularization function is fixed, the method adaptively updates the regularization function using the Bregman distance at different iterations, such that the iteration gradually removes the aliasing artifacts and recovers fine structures before the noise finally comes back. With a discrepancy principle as the stopping criterion, our results demonstrate that the reconstructed image using Bregman iteration preserves both sharp edges lost in Tikhonov regularization and fines structures missed in total variation (TV) regularization, while reducing more noise and aliasing artifacts. Magn Reson Med 61:145–152, 2009. © 2008 Wiley‐Liss, Inc.  相似文献   
93.
94.
Objective The-455 G/A (HaeⅢ) polymorphism of β-fibrinogen gene influences levels of plasma fibrinogen. We further investigated whether it influences the risk of isehemie cerebrovaseular disease. Methods We accumulated 134 acute isehemic eerebrovaseular disease (ICVD) eases and compared their -455 G/A status with a control group (n=166). The β-fibrinogen gene -455 G/A polymorphism was analyzed for all subjects by PCR-RFLP with the restrictive enzyme HaeⅢ. Results Plasma fibrinogen was higher in AA homozygous participants (341mg/dL) than in participants carrying the G allele: GA (290mg/dL), GG (298mg/dL) in the control group. Plasma fibrinogen was also higher in AA homozygous patients (353mg/dL) than in eases carrying the G allele: GA (287mg/dL), GG (302mg/dL) in the ICVD group. However, there was no significant association between β-fibrinogen gene -455 G/A polymorphism and ICVD group. Conclusions Although a small effect cannot be excluded, β-fibrinogen gene -455 G/A polymorphism is an independent predictor of plasma fibrinogen, but not of isehemie cerebrovaacular disease.  相似文献   
95.
人发角蛋白人工腱肌肉植入的组织相容性观察   总被引:5,自引:0,他引:5  
为了研究人发角蛋白人工腱(human hair keratin artifical tendon,HHKAT)材料在体内的降解及其对周围组织的影响,将12只日本大耳白兔随机分组,在脊旁肌埋藏不同处理程度的人发角蛋白人工腱度件F及Z,用正常人发O做对照,分别在2,6,12,24周取材,观察人发角蛋白的降解及其周围的组织反应,结果:实验中发现不同程度处理的HHKAT其降解速度不同,其中降解最快的F组在24周时已完全吸收,而Z组在24周时只有部分降解,O组未见降解,HHKAT及人发在肌肉组织内无明显的炎症排斥反应,随着HHKAT材料的降解吸收,其周围的组织反应逐渐降低,研究表明人发角蛋白人腱材料具有良好的生物相容性,在体内能够被降解吸收,可根据不同的需要调节其降解速度,是良好肌腱替代材料。  相似文献   
96.
Background Double plate osteosynthesis is the standard treatment for intra-articular fractures of the distal humerus. However, there is still controversy concerning dual plate positions in terms of providing optimal stability. The purpose of this retrospective study was to compare the clinical outcomes in patients with type C intra-articular distal humeral fractures using perpendicular and parallel plating methods.
Methods Between March 2008 and June 2011, a total of 45 patients with type C distal humerus fractures were treated using two different dual plating methods. Of them, 24 patients were treated by perpendicular plating (group I) and 21 patients were treated by parallel plating (group II). The surgical time, blood loss, and union time were compared between the two groups. The flexion-extension arc, the total range of flexion and extension at the end of follow-up were compared between the two groups. The Mayo Elbow Performance Score (MEPS) was used to determine the elbow functional results.
Results All patients were followed up. The mean duration of follow-up was 16 months (range 12–25 months) in group I and 15.5 months in group II (range 12–25 months). There were no significant differences in the surgical time, blood loss, and the bone union time between the two groups. In group I, the mean elbow flexion-extension arc was 101° and the mean MEPS was 85 points. The rate of excellent and good results was 87.5%. In group II, the mean flexion-extension arc was 100° and the mean MEPS was 86.1 points. The rate of excellent and good results was 90.5%. There were no significant differences in the MEPS, flexion-extension arc, and the total range of flexion and extension between the two groups.
Conclusions Perpendicular and parallel plate configurations with the appropriate surgical techniques can provide anatomical reconstruction and stable fixation of type C intra-articular distal humeral fractures and allow early mobilization of the elbow after an operation. The occurrence of post-operative elbow stiffness can be reduced and good outcomes can be obtained.
  相似文献   
97.
1 临床资料患者,男,56岁,因反复发作的胸闷、气短于2002年入院,患者缘于2000年2月出现劳力时胸闷、气短,未经治疗,此后上述症状反复发作,于2002年10月上述症状加重,休息时也有胸闷、气短症状,逐渐出现夜间阵发性呼吸困难和端坐呼吸,于当地医院诊断为扩张型心肌病,经治疗无明显好转后转院入我科.入院后给予强心、利尿、扩血管等药物治疗,患者胸闷、气短症状曾一度好转,心电图提示心房纤颤,二维超声心动图可在左室心尖部、前侧壁心内膜面探及多发性突入左室腔内的肌小梁,小梁之间可见深度不同的间隙.  相似文献   
98.
脂代谢紊乱对糖尿病并发症的发生有重要影响。根据中医理论特点,脂毒可以归为"毒"邪概念。该文试着从脂毒及毒损肾络角度出发,探讨糖尿病肾病的发病机制,旨在为临床治疗糖尿病肾病提供新的思路和方法。  相似文献   
99.
In this study, the silica fume replacement rate, fly ash replacement rate, and curing temperature were regarded as the independent variables, and the compressive and flexural strengths were regarded as the response values. The response surface method was used to construct the response surface polynomial regression model and obtain the optimal preparation parameters of a steel slag cement-based gel slurry (SCGS). The univariate and multivariate effects on the SCGS’s strength were investigated via analysis of variance and a three-dimensional surface model, and the hydration products and strength development law were characterized via scanning electron microscopy and X-ray diffraction. The actual compressive strengths at 3 and 28 d of age were 31.78 and 53.94 MPa, respectively, which were close to the predicted values (32.59 and 55.81 MPa, respectively), demonstrating that the optimized strengths were accurate and reliable. Further, the hydration reaction rate of SiO2 in the silica fume and the physical filling effect of the inert components of fly ash and steel slag under the optimal parameters were the key factors for the early strength of the material. Moreover, continuous C3S hydration in steel slag and the continuous excitation of the volcanic ash properties of fly ash were important factors for the later strength.  相似文献   
100.
Objective Lidamycin (LDM) can be dissociated to an apoprotein (LDP) and an active enediyne chromophore (AE).The detached AE can reassemble with its LDP‐containing fusion protein to endow the latter with potent antitumor activity.However,the reassembly of AE with LDP is affected by several factors.Our aim was to optimize the assembly efficiency of the AE with a LDP‐containing fusion protein and investigate the influence of several factors on the assembly efficacy.Methods A method based on RP‐HPLC was develop...  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