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   411320篇
  免费   72667篇
  国内免费   24147篇
耳鼻咽喉   4390篇
儿科学   8078篇
妇产科学   4733篇
基础医学   52678篇
口腔科学   12574篇
临床医学   60877篇
内科学   71136篇
皮肤病学   10802篇
神经病学   30741篇
特种医学   14400篇
外国民族医学   208篇
外科学   45476篇
综合类   56262篇
现状与发展   97篇
一般理论   53篇
预防医学   28064篇
眼科学   10800篇
药学   40284篇
  366篇
中国医学   20611篇
肿瘤学   35504篇
  2024年   1283篇
  2023年   6098篇
  2022年   13495篇
  2021年   18158篇
  2020年   18371篇
  2019年   21187篇
  2018年   21615篇
  2017年   21959篇
  2016年   22123篇
  2015年   26978篇
  2014年   30871篇
  2013年   29656篇
  2012年   28102篇
  2011年   31288篇
  2010年   26634篇
  2009年   20101篇
  2008年   19690篇
  2007年   18405篇
  2006年   18493篇
  2005年   17759篇
  2004年   11364篇
  2003年   10717篇
  2002年   9194篇
  2001年   8299篇
  2000年   8427篇
  1999年   8519篇
  1998年   5646篇
  1997年   5600篇
  1996年   4460篇
  1995年   4115篇
  1994年   3384篇
  1993年   2333篇
  1992年   2534篇
  1991年   2099篇
  1990年   1771篇
  1989年   1550篇
  1988年   1301篇
  1987年   1159篇
  1986年   881篇
  1985年   732篇
  1984年   441篇
  1983年   317篇
  1982年   207篇
  1981年   212篇
  1980年   137篇
  1979年   150篇
  1978年   41篇
  1977年   48篇
  1976年   38篇
  1975年   36篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
European Archives of Oto-Rhino-Laryngology - Several polymorphisms in a disintegrin and metalloproteinase 33 (ADAM33) have been implicated in susceptibility to allergic rhinitis (AR), but the...  相似文献   
3.
4.
5.
Patients with mechanic ankle instability experience increased tibiotalar and subtalar joint laxity. However, in vivo joint kinematics in functional ankle instability (FAI) patients and lateral ankle sprain (LAS) copers, especially during dynamic activities, are poorly understood. Ten FAI patients, 10 LAS copers, and 10 healthy controls were included in this study. A dual fluoroscopic imaging system was used to analyze the tibiotalar and subtalar joint kinematics during stair descent. Five key poses of stair descent were analyzed. Kinematic data from six degrees of freedom were calculated utilizing a solid modeling software. The range of motion and joint positions in each degree of freedom were compared among the three groups. The tibiotalar joints of FAI patients and LAS copers were significantly more inverted than those of healthy controls during the foot strike (p = 0.016, = 0.264). The subtalar joints of FAI patients were significantly more anteriorly translated (pose 2, p = 0.003, = 0.352; pose 3, p < 0.001, = 0.454; pose 4, p = 0.004, = 0.334), inverted (pose 4, p = 0.027, = 0.234; pose 5,p = 0.034, = 0.221), and externally rotated (pose 4, p = 0.037, = 0.217; pose 5; p = 0.004, = 0.331) than those of healthy controls during the mid‐stance and the heel off. The FAI patients showed excessive tibiotalar inversion and subtalar joint hypermobility during stair descent. Meanwhile, the LAS copers maintained subtalar joint stability, and only showed excessive tibiotalar inversion in foot strike. These data provide insight into the mechanisms behind the development of FAI after initial LAS. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1860–1867, 2019  相似文献   
6.
7.
8.
This paper investigates the quantized sliding mode control of Markov jump systems with time‐varying delay. A dynamical adjustment law is explored to quantize the system output. By constructing an observer‐based integral sliding surface, a sliding mode controller is designed to take over the dynamical motion of state estimation and ensure the reachability of sliding surface. A new scaling manner is developed to build the bound between the system output and quantized error. With the help of separation strategies for controller synthesis and general transition probabilities and a lower bound theorem for nonlinear integral terms, a new synthesis method to ensure the required stability and meet the required performance is proposed in the form of linear matrix inequalities. The validity of the proposed control method is illustrated by a numerical example.  相似文献   
9.
1. To investigate Genkwa Flos hepatotoxicity, a cell metabolomics strategy combined with serum pharmacology was performed on human HL-7702 liver cells in this study.

2. Firstly, cell viability and biochemical indicators were determined and the cell morphology was observed to confirm the cell injury and develop a cell hepatotoxicity model. Then, with the help of cell metabolomics based on UPLC-MS, the Genkwa Flos group samples were completely separated from the blank group samples in the score plots and seven upregulated as well as two down-regulated putative biomarkers in the loading plot were identified and confirmed. Besides, two signal molecules and four enzymes involved in biosynthesis pathway of lysophosphatidylcholine and the sphingosine kinase/sphingosine-1-phosphate pathway were determined to investigate the relationship between Genkwa Flos hepatotoxicity and these two classic pathways. Finally, the metabolic pathways related to specific biomarkers and two classic metabolic pathways were analyzed to explain the possible mechanism of Genkwa Flos hepatotoxicity.

3. Based on the results, lipid peroxidation and oxidative stress, phospholipase A2/lysophosphatidylcholine pathway, the disturbance of sphingosine-1-phosphate metabolic profile centered on sphingosine kinase/sphingosine-1-phosphate pathway and fatty acid metabolism might be critical participators in the progression of liver injury induced by Genkwa Flos.  相似文献   

10.
目的:分析鼻塞式同步间歇正压通气(NIPPV)联合布地奈德雾化治疗ARDS(新生儿急性呼吸窘迫综合征)疾病的临床应用效果。方法:纳入病例是2017年5月—2019年11月收治的104例ARDS新生儿,随机平均分为两组。参照组52例采纳CPAP(持续气道正压通气通气)治疗,实验组52例采纳NIPPV+布地奈德雾化治疗,对比两组呼吸机通气时间、用氧时间、住院时间、血气指标以及并发症发生情况。结果:实验组呼吸机通气时间、用氧时间、住院时间均明显短于参照组,差异有统计学意义P<0.05;实验组治疗3 d后PaCO2明显低于参照组,实验组治疗3 d后PH以及PaO2明显高于参照组,差异有统计学意义P<0.05;实验组并发症发生率(3.85%,2/52)明显低于参照组(21.15%,11/52),差异有统计学意义P<0.05。结论:NIPPV+布地奈德雾化可有效缩短ARDS患者机械通气时间,改善血气指标,降低并发症发生率,值得借鉴。  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