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   67201篇
  免费   5714篇
  国内免费   3177篇
耳鼻咽喉   612篇
儿科学   1127篇
妇产科学   905篇
基础医学   8719篇
口腔科学   1151篇
临床医学   8792篇
内科学   12412篇
皮肤病学   911篇
神经病学   5036篇
特种医学   2111篇
外国民族医学   20篇
外科学   8237篇
综合类   6970篇
现状与发展   6篇
一般理论   17篇
预防医学   4145篇
眼科学   1588篇
药学   5990篇
  31篇
中国医学   1920篇
肿瘤学   5392篇
  2024年   103篇
  2023年   730篇
  2022年   1476篇
  2021年   2728篇
  2020年   1968篇
  2019年   2137篇
  2018年   2295篇
  2017年   1880篇
  2016年   1814篇
  2015年   2561篇
  2014年   3220篇
  2013年   3272篇
  2012年   4994篇
  2011年   5386篇
  2010年   2995篇
  2009年   2585篇
  2008年   3804篇
  2007年   3891篇
  2006年   3601篇
  2005年   3661篇
  2004年   2783篇
  2003年   2596篇
  2002年   2396篇
  2001年   1388篇
  2000年   1372篇
  1999年   1508篇
  1998年   901篇
  1997年   915篇
  1996年   680篇
  1995年   625篇
  1994年   528篇
  1993年   408篇
  1992年   555篇
  1991年   494篇
  1990年   428篇
  1989年   384篇
  1988年   367篇
  1987年   321篇
  1986年   311篇
  1985年   270篇
  1984年   188篇
  1983年   176篇
  1982年   148篇
  1981年   151篇
  1980年   112篇
  1979年   122篇
  1978年   93篇
  1977年   82篇
  1974年   66篇
  1973年   62篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
OBJECTIVE: Many patients with haemorrhoids are investigated because of the fear of missing colorectal cancer (CRC). The aim of this study was to determine whether a primarily clinical approach regarding the need for investigation was safe and did not miss patients with CRC. PATIENTS AND METHODS: Data was collected prospectively on 589 consecutive patients with the principle diagnosis of haemorrhoids at first clinic visit. All had clinical assessment including rigid sigmoidoscopy and were treated by phenol injection or banding. They were categorized for (1) no review unless symptoms persisted -'One Stop SOS' (2) outpatient review or (3) investigation. To check for the development of CRC they were contacted by postal questionnaire or telephone interview with a minimum of one year from diagnosis and treatment. All 589 patients were cross-referenced with the Pathology database and the Hospital Information Services System. RESULTS: Four hundred and sixty-nine (80%) answered the questionnaire; 352 patients (60% of the total group) fell in the 'one stop SOS' outpatient category; 95 (16%) patients were followed up to review response to treatment for large haemorrhoids; 105 (18%) were investigated with barium enema (12%), flexible sigmoidoscopy (4%), colonoscopy (1%) and miscellaneous (1%); 37 (6%) patients were either given a haemorrhoidectomy date or referred on with a different diagnosis. No patients selected for 'one-stop' treatment developed CRC. Five (0.8%) patients were diagnosed with CRC after appropriate investigation was instituted for suspicious symptoms. One patient with distal transverse colon cancer had a delayed diagnosis as she was investigated initially by flexible sigmoidoscopy. CONCLUSION: Most patients with the primary diagnosis of symptomatic haemorrhoids do not need investigation.  相似文献   
142.
The acquisition of new food allergy after orthotopic liver transplantation is now a well described phenomenon, mainly reported in children. The etiology of this phenomenon is at present unclear, but has been ascribed by some to tacrolimus treatment. Here we report a case of liver transplant acquired food allergy (LTAFA) in a child who received a split liver graft. The case is remarkable for the absence of new food allergy in the adult recipient of the same graft. This suggests that host-specific factors play an important role in the development of food allergy after liver transplantation, and emphasizes the predisposition that children have toward this phenomenon. Possible mechanisms underlying the development of food allergy after liver transplantation are discussed. In conclusion, tacrolimus treatment alone cannot account for LTAFA. Host factors such as the maturity of immune regulatory mechanisms are likely to play a critical role in the development of new food allergy after a liver transplant.  相似文献   
143.
Preconditioningofbraintissueswithsub lethalstressesorstimulicanresultinresistancetosubse quentlethalischemiceventsinaresponsecalledis chemictolerance .Recently ,severalstudieshaveshownthatasinglesystemicdoseof 2 0mg/kg 3 NPAcausednohistopathologicalabnorm…  相似文献   
144.
145.
目的 体外研究锤头型α1Ⅰ型及Ⅲ型前胶原基因第2外显子片段核酶对各自靶RNA分子的切割活性及反应条件。同时观察两反义核酶对瘢痕中成纤维细胞胶原合成的影响。方法 将含α1Ⅰ型及Ⅲ型前胶原基因第2外显子片段的重组质粒(pT-Ⅰ、pT-Ⅲ),经体外^32P标记转录后形成产物靶RNA。同时将含特异性核酶基因的重组质粒(pT-gⅠ、pT-gⅢ)进行非标记的体外转录,产物(核酶)与各自的^32P-靶RNA按不同的条件混和反应,电泳后放射自显影观察结果。将构建好的核酶以脂质体包裹后导入培养的成纤维细胞内,采用图像分析法观察核酶对成纤维细胞Ⅰ型、Ⅲ型胶原蛋白mRNA合成的影响。结果 两种核酶在37℃、42℃均能有效切割各自的靶RNA,对Mg^2 浓度的要求范围较宽(10~20mmol/L);反应温度从65℃逐渐降至并维持在37℃的条件下核酶切割活性显提高。Ⅰ、Ⅲ型胶原蛋白mRNA的表达明显降低,胶原蛋白生成降低,胶原生成明显受抑制。结论 针对α1Ⅰ型及Ⅲ型前胶原基因第2外显子片段的核酶能有效地在体外对靶RNA进行切割并能有效地抑制瘢痕中成纤维细胞胶原的合成。  相似文献   
146.
BACKGROUND AND PURPOSE: Health-related quality of life (HRQOL) is primarily an assessment of how domains of life are affected by health. This study investigated the factors influencing HRQOL of Taiwanese patients with bronchial asthma. METHODS: A cross-sectional study was conducted to assess the factors influencing HRQOL. The sample consisted of 242 outpatients with bronchial asthma. The Chinese language version of the St. George's Respiratory Questionnaire was used to measure HRQOL. Data were analyzed using simple regression and multiple regression. RESULTS: Age, marital status, level of education, asthma severity, peak expiratory flow, and previous hospital admissions were found to be predictors of HRQOL. Gender, duration of disease, and history of emergency visits were not correlated with HRQOL. The variables entered in the HRQOL model accounted for 17.4% of the total variance (adjusted R(2)). The regression coefficients indicated that the mean scores increased 7.68 in patients with moderate to severe disease severity, and increased 7.34 in patients with a history of hospital admissions. The mean scores decreased 7.60 in married patients. CONCLUSION: This study found that marital status, asthma severity, and history of hospital admissions were major predictors of HRQOL in Taiwanese patients with bronchial asthma.  相似文献   
147.
六神丸及其加味抗急性白血病的实验研究   总被引:4,自引:0,他引:4  
本研究从血象、骨髓、病理、骨髓细胞增殖动力学的角度证明:六神丸具有明显的抑制和杀伤实验白血病小鼠(L7212)白血病细胞的作用(主要机理类似细胞毒剂),具有缓解、减轻白血病细胞对肝脾浸润,明显延长白血病小鼠生存期的作用;六神丸加味(加用清热解毒方、活血化淤方、益气养阴方、补气养血方、补肾方)和六神丸具有明显的协同作用。  相似文献   
148.
本文测定了对照组及两个萘普生(前列腺素合成酶抑制剂)处理组大鼠着床期宫内PGF2α的含量。结果表明,对照组、萘普生低剂量组(2mg/kg体重)和高剂量组(20mg/kg体重)的PGF2α含量分别为6.71±0.93、2.19±0.34和1.01±0.18ng/100g组织(三组间P<0.01)。同时,还观察到在本实验条件下,萘普生无明显干扰节育器抗生育作用,药物本身亦未呈现显著抗生育活性。  相似文献   
149.
The hemodynamic effects of dopamine and dobutamine (at doses of 6 micrograms X kg-1 X min-1) were compared during fluid resuscitation from septic shock induced by endotoxin (3 mg/kg) in the dog. In the first part of the study, when a standard amount of saline solution was infused (in 24 dogs), dopamine infusion resulted in higher cardiac filling pressures than did dobutamine infusion, whereas dobutamine infusion resulted in higher cardiac output. In the second part of the study, when fluid infusion was titrated to maintain pulmonary artery balloon-occluded pressure at constant level (in 24 dogs), the total amount of fluids was significantly greater with dobutamine than when dopamine was used (109 +/- 13 vs 71 +/- 10 ml/kg). The combination of dobutamine with fluids resulted in significantly greater stroke volume (39.6 +/- 3.8 vs 21.0 +/- 4.0 ml, P less than 0.05) and oxygen consumption (194 +/- 18 vs 144 +/- 8 ml/min, P less than 0.05). The different effects of dopamine and dobutamine on cardiac filling pressures can be due to differences in effects on myocardial contractility, ventricular afterload, and cardiac compliance. This experimental study indicates that when fluid therapy is combined with adrenergic agents in resuscitation from septic shock, dobutamine can be associated with higher cardiac output and oxygen transport and can result in higher tissue oxygen consumption than dopamine.  相似文献   
150.
As for the majority of antiepileptic drugs, encephalopathy, manifested by transient somnolence, mood and motor disorders, is a possible side-effect. To our knowledge, there is little information about gabapentin-induced coma. We report a third case of gabapentin-induced coma where magnetic resonance-spectrometry was performed in diagnosis assessment.  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