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   90658篇
  免费   8305篇
  国内免费   5617篇
耳鼻咽喉   1041篇
儿科学   1573篇
妇产科学   1402篇
基础医学   9402篇
口腔科学   1444篇
临床医学   11761篇
内科学   13275篇
皮肤病学   1410篇
神经病学   4211篇
特种医学   2952篇
外国民族医学   41篇
外科学   7964篇
综合类   15699篇
现状与发展   10篇
一般理论   14篇
预防医学   7171篇
眼科学   2032篇
药学   10569篇
  75篇
中国医学   5714篇
肿瘤学   6820篇
  2024年   288篇
  2023年   1224篇
  2022年   3245篇
  2021年   4133篇
  2020年   3274篇
  2019年   2749篇
  2018年   2988篇
  2017年   2863篇
  2016年   2657篇
  2015年   4125篇
  2014年   5131篇
  2013年   5000篇
  2012年   7404篇
  2011年   7988篇
  2010年   5609篇
  2009年   4456篇
  2008年   5444篇
  2007年   5130篇
  2006年   4912篇
  2005年   4516篇
  2004年   3193篇
  2003年   2907篇
  2002年   2391篇
  2001年   1930篇
  2000年   1733篇
  1999年   1654篇
  1998年   973篇
  1997年   960篇
  1996年   710篇
  1995年   631篇
  1994年   537篇
  1993年   383篇
  1992年   546篇
  1991年   470篇
  1990年   369篇
  1989年   317篇
  1988年   297篇
  1987年   293篇
  1986年   211篇
  1985年   191篇
  1984年   143篇
  1983年   75篇
  1982年   50篇
  1981年   67篇
  1980年   44篇
  1979年   51篇
  1978年   49篇
  1977年   35篇
  1976年   29篇
  1973年   32篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Direct peroral cholangioscopy (POC) using an ultra‐slim upper endoscope is one modality of POC for intraductal endoscopic evaluation and treatment of the bile duct. Choledochoduodenostomy (CDS) is one modality of biliary bypass surgery that provides a new route to the bile duct. We carried out direct POC using an ultra‐slim upper endoscope without the use of accessories in 10 patients (four sump syndromes, three bile duct strictures and three intrahepatic duct stones) previously undergoing surgical CDS. Direct POC was successful in all patients. The use of an intraductal balloon catheter was required in one patient for advancement of the endoscope into the bile duct. Distal bile ducts with sump syndromes were cleared using baskets and water irrigation under direct POC. Cholangiocarcinoma was diagnosed in one patient with hilar bile duct stricture after cholangioscopic evaluation and a targeting forceps biopsy under direct POC. Intrahepatic duct stones were successfully extracted after intraductal fragmentation under direct POC. Oozing bleeding occurred during intraductal lithotripsy but stopped spontaneously. Direct POC using an ultra‐slim upper endoscope without the assistance of accessories can easily be carried out in patients undergoing CDS.  相似文献   
2.
3.
This study investigated the hypocholesterolaemic effects of bitter melon aqueous extracts (BMAE) in vitro, the inhibitory effects of BMAE on pancreatic cholesterol esterase (CEase) and incorporation of cholesterol into micelles were investigated. BMAE decreased the in vitro micellar solubility of cholesterol in a dose-dependent manner. The conformation of CEase was investigated by means of circular dichroism (CD) and fluorescence. The result revealed the decrease of α-helix contents, increase of β-sheet and exposure of aromatic amino acid residuals. The incorporation of cholesterol into micelles was inhibited by BMAE. A complex was observed by transmission electron microscopy (TEM), which indicated interaction between cholesterol and BMAE. The result revealed that BMAE can play a role in decreased intestinal cholesterol absorption via inhibition of CEase, and of micelle formation.  相似文献   
4.
5.
田方  石文 《中国当代儿科杂志》2015,17(10):1142-1147
动脉导管未闭(PDA)是早产儿常见疾病,目前早产儿PDA的自然发展过程仍未完全明确,PDA发生的有些高危因素仍存在争议,对PDA是否进行药物、手术干预,以及何时进行药物、手术干预仍存在争议。尽管已经有相当多的证据证实动脉导管持续开放可能有害,但目前尚缺乏关闭导管治疗方案的远期益处或害处的相关证据。大多数临床试验旨在评估短期导管开放对患儿的影响。目前尚无评估动脉导管持续开放对早产儿死亡率及并发症影响的临床试验。近年来PDA治疗上最大的变化是减少对PDA的治疗。该文重点总结胎龄28周早产儿PDA的治疗策略。  相似文献   
6.
7.
Objective: To study the biomechanical mechanism of head injuries beaten with sticks, which is common in the battery or assaultive cases. Methods: In this study, the Hybrid-III anthropomorphic test device and finite element model (FEM) of the total human model for safety (THUMS) head were used to determine the biomechanical response of head while being beaten with different sticks. Total eight Hybrid-III tests and four finite element simulations were conducted. The contact force, resultant acceleration of head center of gravity, intracranial pressure and von Mises stress were calculated to determine the different biomechanical behavior of head with beaten by different sticks. Results: In Hybrid-III tests, the stick in each group demonstrated the similar kinematic behavior under the same loading condition. The peak values of the resultant acceleration for thick iron stick group, thin iron stick group, thick wooden stick group and thin wooden stick group were 203.4 g, 221.1 g, 170.5 g and 122.2 g respectively. In finite element simulations, positive intracranial pressure was initially observed in the frontal comparing with negative intracranial pressure in the contra-coup site. Subsequently the intracranial pressure in the coup site was decreasing toward negative value while the contra-coup intracranial pressure increasing toward positive values. Conclusions: The results illustrated that the stiffer and larger the stick was, the higher the von Mises stress, contact force and intracranial pressure were. We believed that the results in the Hybrid-III tests and THUMS head simulations for brain injury beaten with sticks could be reliable and useful for better understanding the injury mechanism.  相似文献   
8.
Multidisciplinary predialysis education and team care (MDC) may slow the decline in renal function in patients with chronic kidney disease (CKD). However, associations between unexpected return during MDC and progression of renal dysfunction have not been characterized in patients with CKD. Our study aimed to determine the association between exacerbation of renal dysfunction and the frequency of unexpected return during follow-up.A total of 437 patients with CKD receiving multidisciplinary care between January 2009 and June 2013 at the Shin-Kong Wu Ho-Su Memorial Hospital were included in this retrospective observational cohort study, and multiple imputations were performed for missing data. The predictor was the frequency of unexpected return for follow-up during the first year after entering MDC. Main outcome was monthly declines in estimated glomerular filtration rates (eGFR). Moreover, the demographic data, comorbidities, history of medication, and routine laboratory data for patients with CKD were collected.Among all patients, 59.7% were male, the mean age at initiation of MDC was 69.4 ± 13.2 years, and the duration of follow-up was 21.4 ± 3.3 months. The subjects were divided into 2 groups according to frequencies of follow-up (≤4 and > 4 visits) during the 1st year of MDC. The patients with CKD were regularly followed up every 3 months as a part of MDC in our hospital, and patients who returned for more than 4 follow-up visits were included in the unexpected return group. In crude regression analyses, unexpected return was significantly associated with higher monthly declines of eGFR (β = 0.092, 95% confidence interval, 0.014–0.170). This association remained after adjustments for multiple variables, and subgroup analyses of unexpected return showed that male gender, older age, CKD stage 1 to 3, hypertension, history of coronary artery disease, and use of renin–angiotensin system blockade were significantly associated with declines in renal function.In conclusion, unexpected return for follow-up during the 1st year of MDC was significantly associated with the deterioration of renal function.  相似文献   
9.
10.
目的:探讨血清亮氨酸氨基肽酶(LAP)在妊娠妇女不同时期血清中的变化规律及其临床意义。方法:选取2011年1月~2013年12月在该院产检的正常妊娠妇女180例,根据孕周分为早期组、中期组和晚期组,每组各60例,另选取60例健康未孕妇女为未孕组;同时选取该院收治的妊娠期高血压疾病妇女33例为妊娠期高血压疾病组、早产孕妇22例为早产组,采用速率法分别检测各组孕妇血清LAP水平并进行比较。结果:未孕组、早期组、中期组、晚期组妇女的血清LAP、血清肝胆酸(CG)、碱性磷酸酶(ALP)、α-L-岩藻糖苷酶(AFU)水平比较,差异有统计学意义(P均<0.05)。妊娠期高血压疾病组的CG、ALP、AFU、LAP水平显著高于早期组、中期组和晚期组(P均<0.05);早产组的CG、ALP、AFU、LAP水平显著高于早期组、中期组(P均<0.05),仅CG水平高于晚期组(P<0.05)。结论:随着妊娠周期的增加,妊娠妇女的血清LAP水平逐步升高,在合并妊娠期高血压疾病时LAP升高更加显著,结合CG、ALP、AFU水平的变化能够对妊娠期高血压疾病的发病情况进行动态监测。  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