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   38419篇
  免费   1908篇
  国内免费   261篇
耳鼻咽喉   490篇
儿科学   720篇
妇产科学   596篇
基础医学   4763篇
口腔科学   971篇
临床医学   2663篇
内科学   10549篇
皮肤病学   542篇
神经病学   2729篇
特种医学   1365篇
外科学   6547篇
综合类   151篇
一般理论   1篇
预防医学   1026篇
眼科学   525篇
药学   2513篇
中国医学   71篇
肿瘤学   4366篇
  2023年   191篇
  2022年   351篇
  2021年   841篇
  2020年   470篇
  2019年   554篇
  2018年   780篇
  2017年   595篇
  2016年   746篇
  2015年   744篇
  2014年   973篇
  2013年   1271篇
  2012年   1912篇
  2011年   2145篇
  2010年   1162篇
  2009年   1026篇
  2008年   1929篇
  2007年   2169篇
  2006年   2005篇
  2005年   1974篇
  2004年   1967篇
  2003年   1884篇
  2002年   1936篇
  2001年   1055篇
  2000年   1072篇
  1999年   970篇
  1998年   538篇
  1997年   396篇
  1996年   365篇
  1995年   340篇
  1994年   314篇
  1993年   294篇
  1992年   682篇
  1991年   715篇
  1990年   597篇
  1989年   609篇
  1988年   570篇
  1987年   540篇
  1986年   455篇
  1985年   458篇
  1984年   342篇
  1983年   266篇
  1982年   139篇
  1979年   243篇
  1978年   154篇
  1977年   148篇
  1974年   144篇
  1972年   138篇
  1971年   133篇
  1969年   139篇
  1967年   129篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
1.
2.
3.
4.
5.
6.
7.
BackgroundAdjacent vertebral fracture (AVF) is a major complication following Balloon Kyphoplasty (BKP). There is no scoring system for predicting AVF using only preoperative elements. The purposes of this study were to develop a scoring system for predicting early AVF after BKP based on preoperative factors and to investigate the appropriate surgical indication for BKP.MethodsOf 220 patients who underwent BKP at a single institution since 2011, 65 patients over the age of 60 who had undergone a standing whole spine X-ray preoperatively were enrolled. Factors affecting the occurrence of early AVF were examined. A scoring system was created consisting of the factors exhibiting significant differences, and the correlation between the total score and the incidence of early AVF was investigated.ResultsTwenty of the 65 patients (30.8%) had early AVF. In a univariate analysis, age, previous vertebral fracture, pelvic tilt, and Local kyphosis significantly influenced early AVF. In a multivariate logistic regression analysis, age had an odds ratio of 1.136 (95% CI 1.001–1.289), previous vertebral fractures 4.181 (1.01–17.309), and Local kyphosis 1.103 (1.021–1.191). The scoring system was set as follows: ①Age (<75 years: 0 points(P), 75years≦: 1P), ②The number of previous vertebral fractures (0: 0 P, 1: 1P, 2: 2P, 3 or more: 3P), and ③Local kyphosis (<10°: 0P, 10°≦: 1P). There was a correlation between the total score and the incidence of early AVF (r = 0.812, 1P = 0.05). The incidence of early AVF was 6.4% (2 cases/31 cases) for a score of ≦1P and 54.5% (18 cases/33 cases) for a score of ≧2P.ConclusionsThere was a correlation between the total score and the incidence of early AVF. A score of 1 point or less may represent the appropriate surgical indication for BKP.  相似文献   
8.
A 1:1 adduct of methyl sorbate (MS) and 1,3‐di‐tert‐butylimidazol‐2‐ylidene (NHCtBu) initiates anionic polymerization of a nonconjugated polar alkene, allyl methacrylate (AMA) in toluene at ?20 °C. After the monomer is consumed quantitatively using a bulky aluminum Lewis acid, methylaluminum bis(2,6‐di‐tert‐butyl‐4‐methylphenoxide) (MAD), as an additive, successive ring‐closure occurs without highly dilute conditions to give a cyclic poly(AMA) containing α‐terminal MS unit, and an Mn of 8.8 × 103?58.5 × 103 with a narrow molecular dispersity index (Mw/Mn = 1.14–1.37). The lack of a need for dilution is due to the fact that an α‐terminal NHCtBu group is acting as the counter cation for the propagating center in the polymerization. From 1H NMR and matrix assisted laser desorption/ionization (MALDI‐TOF) mass spectra, combined with transmittance electron microscope (TEM) observation of a synthesized poly(AMA) with longer alkyl side chains prepared via a thiol‐ene click reaction, it is concluded that once the monomer is consumed, nucleophilic attack at the neighboring methine of the α‐terminal NHCtBu residue by the propagating anionic center causes ring‐closing to cyclic poly(AMA).  相似文献   
9.
Burning mouth syndrome (BMS) is a chronic oro‐facial pain disorder of unknown cause. It is more common in peri‐ and post‐menopausal women, and sex hormone dysregulation is believed to be an important causative factor. Psychosocial events often trigger or exacerbate symptoms, and persons with BMS appear to be predisposed towards anxiety and depression. Atrophy of small nerve fibres in the tongue epithelium has been reported, and potential neuropathic mechanisms for BMS are now widely investigated. Historically, BMS was thought to comprise endocrinological, psychosocial and neuropathic components. Neuroprotective steroids and glial cell line–derived neurotrophic factor family ligands may have pivotal roles in the peripheral mechanisms associated with atrophy of small nerve fibres. Denervation of chorda tympani nerve fibres that innervate fungiform buds leads to alternative trigeminal innervation, which results in dysgeusia and burning pain when eating hot foods. With regard to the central mechanism of BMS, depletion of neuroprotective steroids alters the brain network–related mood and pain modulation. Peripheral mechanistic studies support the use of topical clonazepam and capsaicin for the management of BMS, and some evidence supports the use of cognitive behavioural therapy. Hormone replacement therapy may address the causes of BMS, although adverse effects prevent its use as a first‐line treatment. Selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs) may have important benefits, and well‐designed controlled studies are expected. Other treatment options to be investigated include brain stimulation and TSPO (translocator protein 18 kDa) ligands.  相似文献   
10.
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