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   3796篇
  免费   248篇
  国内免费   118篇
耳鼻咽喉   1篇
儿科学   35篇
妇产科学   9篇
基础医学   417篇
口腔科学   38篇
临床医学   151篇
内科学   344篇
皮肤病学   355篇
神经病学   78篇
特种医学   54篇
外科学   212篇
综合类   346篇
现状与发展   1篇
预防医学   168篇
眼科学   37篇
药学   1373篇
中国医学   423篇
肿瘤学   120篇
  2024年   5篇
  2023年   25篇
  2022年   60篇
  2021年   96篇
  2020年   93篇
  2019年   99篇
  2018年   98篇
  2017年   80篇
  2016年   89篇
  2015年   113篇
  2014年   195篇
  2013年   213篇
  2012年   252篇
  2011年   261篇
  2010年   252篇
  2009年   196篇
  2008年   234篇
  2007年   229篇
  2006年   197篇
  2005年   179篇
  2004年   166篇
  2003年   148篇
  2002年   119篇
  2001年   119篇
  2000年   85篇
  1999年   75篇
  1998年   56篇
  1997年   46篇
  1996年   57篇
  1995年   51篇
  1994年   49篇
  1993年   25篇
  1992年   36篇
  1991年   18篇
  1990年   18篇
  1989年   13篇
  1988年   20篇
  1987年   15篇
  1986年   10篇
  1985年   16篇
  1984年   14篇
  1983年   7篇
  1982年   7篇
  1981年   8篇
  1980年   7篇
  1979年   4篇
  1978年   3篇
  1977年   2篇
  1971年   1篇
  1969年   1篇
排序方式: 共有4162条查询结果,搜索用时 0 毫秒
21.
Objective: Although the propulsion distance of a wheelchair is measured by some devices, measuring self-propulsion distance, excluding assistance propulsion distance by the caregiver, is difficult. This is a pilot study conducted to verify whether the propulsion distance of wheelchair users, excluding the assistance propulsion distance, can be measured using a cycle computer by attaching the touch switch.Methods: The wheelchair propulsion distance was measured using a cycle computer. We connected the touch switch and the cycle computer to the wheelchair to exclude assistance propulsion distance. We set the cycle computer to stop recording while the caregiver was touching the sensor. To confirm the propulsion distance using the cycle computer, the volunteer propelled the wheelchair on a rectangular facility with a total distance of 181 m, and the examiner confirmed the propulsion distance. The validation test to confirm the accuracy of the touch switch attached to the cycle computer was performed on a 50-m straight runway. The volunteer and caregiver propelled the wheelchair alternately by 10 m and continued until 50 m. The examiner confirmed the distance after 50-m propulsion.Results: In the 181-m rectangular facility, the propulsion distance that the volunteer propelled the wheelchair with the cycle computer was 180 m. In the 50-m straight runway, the propulsion distance was 30 m with caregiver assistance for 20 m.Conclusion: The present study showed that our modified device could measure the self-propulsion distance, excluding assistance propulsion distance in wheelchair users.  相似文献   
22.
利用药材性状、显微特征、紫外吸收光谱和薄层层析等鉴别方法对香青藤进行生药鉴定研究 ,为该药材的鉴别和开发利用提供科学依据  相似文献   
23.
采用反相高效液相色谱蒸发激光散射检测器测定三七中人参皂苷Rg1的含量。色谱柱为CLC-ODS(6.0mm×150mm),流动相为乙腈-水(3070),蒸发激光散射检测器。定量方法简单,准确。回收率为100.50%,RSD为1.82%。并用紫外分光光度法测定了三七中总皂苷的含量,结果和HPLC法基本一致,说明该方法定量准确,回收率为101.50%,RSD为1.44%。结论认为两方法均可以控制三七的质量。  相似文献   
24.
Background: Hybrid, combined or mixed bariatric surgery is the combination of a degree of ‘malabsorption’ (as achieved by the intestinal bypass) with a ‘rrestriction’ (as achieved by gastric bypass or gastroplasty), thereby simultaneously reducing the absorption of fats in the small bowel and decreasing the intake of food. Methods: A modification of the bilio-pancreatic diversion (BPD) with a duodenal switch procedure, vertical lineal gastrectomy and preservation of the pylorus, has been used in 23 patients. The antropyloric pump and 4 cm of the duodenum are left intact to preserve physiologic gastric emptying and to prevent anastomotic ulcer. The use of staplers and continuous running sutures reduces surgical risks and operative time. Results: One patient, converted from a vertical gastroplasty, had an intrathoracic esophageal perforation and died of multisystemic organ failure, a mortality rate of 4.5%. One patient had a partial dehiscence of the laparotomy wound. Three patients developed subcutaneous seromas. Mean weight losses during the first 4 months were 13, 11, 6 and 5 kg, with a loss of 70% of excess weight in patients approaching 1 year. No patient needs treatment for diarrhea. No serious secondary side-effects have been detected. Conclusion: This operation appears to result in very satisfactory weight loss, improved quality of life, and a low incidence of complications.  相似文献   
25.
Aortopulmonary collateral arteries sometimes complicate cyanotic congenital heart defects. Combined with a relevant left-right shunt, this could result in massive airway bleeding during and after corrective surgery. A preoperatively diagnosed 1.2 mm small aortopulmonary collateral artery in a newborn suffering from transposition of the great arteries caused life-threatening airway bleeding during surgery. Postoperative extracorporeal membrane oxygenation (ECMO) was necessary, and coil embolization was performed on ECMO to terminate pulmonary bleeding.  相似文献   
26.
介绍了基于Windows3.x环境下,用Delphi开发软件,结合面象对象技术、数据库技术、Windows帮助文件系统技术,开发S12数字程控交换机人机命令信息查询系统的过程和方法.并对超文本技术、面向对象技术、数据库技术进行了阐述.通过试运行,验证了本系统的高速、方便、安全、兼容性好等特点.  相似文献   
27.
Hypomanic episodes in two cases involving depressed patients (bipolar II) were observed after admission to an open psychiatric ward. The patients had not exhibited any prior (hypo)manic episodes during outpatient treatment. Thus, manic switching was thought to have been caused by the psychological effects brought on by the change in environment due to hospital admission. Hospital admission was believed to have been an unloading from their stressful lives, given that the affective state of both patients prior to admission was characterized by depression resulting from work-related stress. The close relationship between the patients and the predominantly female nursing staff may have triggered a psychological regression in both patients. These factors appear to have led to the hypomanic switching.  相似文献   
28.
替米沙坦片的含量测定   总被引:9,自引:0,他引:9  
目的 测定替米沙坦片中替米沙坦的含量。方法 采用紫外分光光度法 ,在 2 96nm波长处测定 ,空白辅料无干扰。结果 替米沙坦浓度在 4× 10 -3 ~ 16× 10 -3 mg·ml-1范围内与吸光度有良好的线性关系 (r =0 .9999)。平均回收率为 99.75 %。重复性试验的 RSD =0 .37%。结论 所建立的方法简便、灵敏、专属、准确 ,可供替米沙坦片的含量测定。  相似文献   
29.
夏玉凤  王强  濮祖茂 《中药材》2003,26(5):323-326
分别采用扫描电镜和紫外光谱法对地肤子、藜、小藜和扫帚菜四种药材进行了比较鉴别。结果表明:扫描电镜下四种药材的胞果、毛茸、气孔和种子形态特征有较为明显的区别;紫外光谱扫描结果表明地肤子和扫帚菜无明显区别,但与藜和小藜之间有显著区别。  相似文献   
30.
高晓黎  陈新梅 《中国药师》2003,6(5):277-278,285
目的 :建立用紫外分光光度法测定尼美舒利栓中尼美舒利的含量。方法 :用不同的有机溶剂萃取尼美舒利栓中的基质 ,用紫外分光光度法测定尼美舒利的含量。结果 :用正己烷作为萃取剂。用紫外分光光度法测定尼美舒利栓的含量 ,标准曲线线性好尼美舒利线性范围为 3~ 15 μg·ml-1(r =0 .9999)、回收率较好 (98.3% )。结论 :用紫外分光光度法测定尼美舒利栓剂的含量 ,方法简便、快速、结果准确 ,可作为尼美舒利含量测定的方法。  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