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   252679篇
  免费   13252篇
  国内免费   6788篇
耳鼻咽喉   2853篇
儿科学   9346篇
妇产科学   3636篇
基础医学   18196篇
口腔科学   4569篇
临床医学   29499篇
内科学   47031篇
皮肤病学   3316篇
神经病学   12189篇
特种医学   12859篇
外国民族医学   24篇
外科学   37160篇
综合类   23128篇
现状与发展   35篇
一般理论   3篇
预防医学   21391篇
眼科学   4833篇
药学   25335篇
  107篇
中国医学   5020篇
肿瘤学   12189篇
  2023年   2194篇
  2022年   7311篇
  2021年   11100篇
  2020年   6058篇
  2019年   12654篇
  2018年   7822篇
  2017年   6172篇
  2016年   7430篇
  2015年   10387篇
  2014年   19194篇
  2013年   16864篇
  2012年   20042篇
  2011年   16879篇
  2010年   15417篇
  2009年   14903篇
  2008年   13335篇
  2007年   13349篇
  2006年   11201篇
  2005年   7458篇
  2004年   3812篇
  2003年   3320篇
  2002年   2654篇
  2001年   2154篇
  2000年   1919篇
  1999年   1254篇
  1998年   1668篇
  1997年   1543篇
  1996年   1258篇
  1995年   1299篇
  1994年   1244篇
  1993年   921篇
  1992年   1145篇
  1991年   1015篇
  1990年   1059篇
  1989年   1039篇
  1988年   954篇
  1987年   842篇
  1985年   2293篇
  1984年   2776篇
  1983年   2067篇
  1982年   2199篇
  1981年   2154篇
  1980年   1881篇
  1979年   1829篇
  1978年   1549篇
  1977年   1292篇
  1976年   1367篇
  1975年   1019篇
  1974年   1000篇
  1973年   1010篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
7β-(6-取代-2-喹诺酮-3-乙酰氨基)头孢菌素的合成   总被引:1,自引:0,他引:1  
以6-取代-2-喹诺酮-3-乙酸为侧链,用CDI法和潘化酯法与7-ADCA,7-ACA,7-ACT,和7-ACD缩合,合成了16个新的7β-(6-取代-2-喹诺酮-3-乙酰氨基)头孢菌素类化合物,通过溶媒转提,葡聚糖凝胶(Sephadex LH-20)柱层析及离心薄层层析分离精制,得到纯品。初步体外抑菌试验表明:新化合物对革兰氏阳性及某些阴性菌具有高度敏感性。大多数化合物对所试试验菌的抗菌活性与头孢唑啉和青霉素G钠相当,有些比它们还强。  相似文献   
982.
Intercostal catheterization   总被引:1,自引:0,他引:1  
Twenty-one patients scheduled to undergo thoracotomy or median sternotomy had intercostal catheters inserted pre-operatively. During thoracotomy, under direct vision, the spread of 20 ml of a solution containing bupivacaine and methylene blue was followed. In most cases the spread involved one or two intercostal spaces. However, in all but one patient, dye spread medially to the paravertebral space where it then spread in both caudad and cephalad directions to reach between two and five vertebrae. In three cases, dye was seen crossing the anterior surface of the vertebrae to reach the contralateral aspect. It is concluded that a major component of dermatomal block during intercostal catheterisations may be secondary to paravertebral spread.  相似文献   
983.
A clinical discussion is presented of sources of sexual stress for women and how they might interfere with healthy sexual functioning. Several therapeutic techniques to reduce sexual stress are described and clinical case examples are given to clarify their use in clinical practice.  相似文献   
984.
目的了解那曲地区藏族学生龋病患病情况,为当地制定口腔预防保健措施提供基线资料。方法采用单纯随机抽样方法,按照WHO 1997年的《口腔健康调查基本方法》,对12~17岁的471名藏族学生进行恒牙龋病检查。结果藏族学生恒牙总患龋率为56.7%,男生患龋率为53.9%,女生患龋率为59.1%,差异无统计学意义(χ2=1.258,P=0.262);龋均为(4.09±2.11),男生龋均为(4.04±2.10),女生龋均为(4.13±2.11),差异无统计学意义(t=-0.646,P=0.518)。结论那曲地区藏族学生恒牙龋病患病率较高、程度较重,预防治疗措施急需加强。  相似文献   
985.
Zusammenfassung Für die Todeszeitbestimmung kann der Speisebreiverteilung im Magendarmtrakt zentrale Bedeutung zukommen. Dabei würde die Zeitschätzung durch eine postmortale Magenentleerung zusätzlich erschwert. Auch anhand radiologischer Kontrolle unmittelbar postmortal in den Magen applizierten Röntgenkontrastbreies fand sich kein Anhalt für eine postmortale peristaltische Entleerung des Mageninhaltes im Tierexperiment.Herrn Prof. Dr. S. Berg in Verehrung zum 65. Geburtstag gewidmet  相似文献   
986.
Two unusual cases of delayed synthetic graft complications resulting from manufacturing defects of knitted Dacron are presented. Computed tomography appears to be a suitable noninvasive alternative examination to angiography in this condition.  相似文献   
987.
A group of 153 children (51 with a history of bronchiolitis and 102 matched controls) were evaluated in a historical cohort study at a mean age of 8 years and again at 13 years to test the primary hypothesis that mild bronchiolitis, far more common than severe (hospitalized) bronchiolitis, predicts wheezing. A secondary hypothesis was that passive smoking also predicts wheezing. Many potentially confounding variables such as family history of asthma were controlled in analyses. Analysis at 13 years produced results that were not anticipated from previous analysis of interviews at age 8. Although mild bronchiolitis was a powerful predictor of wheezing at age 8 years, it was no longer a strong predictor of wheezing at age 13 in either bivariate or multivariate analysis. Although epidemiologic studies, by their nature, cannot prove causality, findings are consistent with the hypothesis that sequelae often follow mild bronchiolitis but diminish during childhood. Maternal smoking was a powerful predictor of wheezing at age 13 in bivariate analysis (Kendall's Tau B = 0.19, P less than 0.01) and in multivariate analysis (odds ratio = 2.67, P less than 0.01). In children at highest risk for wheezing, males with a family history of asthma, multivariate analysis suggested that maternal smoking is associated with an increase in wheezing from 36% to 60%. We conclude that passive smoking, previously identified as a risk factor in this population for both bronchiolitis in infancy and wheezing at age 8, is a risk factor for wheezing-associated morbidity throughout the childhood years.  相似文献   
988.
腹腔镜与开腹幽门环肌切开术的前瞻性比较研究   总被引:2,自引:0,他引:2  
目的研究比较腹腔镜幽门环肌切开术(LP)和开腹幽门环肌切开术(OP)治疗先天性幽门肥厚性狭窄的疗效及免疫功能的变化。方法自2003年4月-2006年7月将72例先天性幽门肥厚性狭窄患儿随机分成二组(LP组及OP组各36例),比较二组麻醉时间、手术时间、术后进食时间及术后并发症,监测二组术前、术后第一天、术后第三天的外周血T淋巴细胞亚群、C反应蛋白(CRP)及白细胞介素-6(IL-6)和肿瘤坏死因子(TNF)的变化并行对比研究。结果二组麻醉时间、手术时间、术后进食时间差异无统计学意义,OP组术后并发症要略多于LP组,比较二组术前、术后第一天、术后第三天的外周血T淋巴细胞亚群、CRP及IL-6和TNF的变化差异无统计学意义。结论腹腔镜幽门环肌切开术(LP)和开腹幽门环肌切开术(OP)治疗先天性幽门肥厚性狭窄的临床效果相近,二组患儿免疫功能的变化无显著性差异。腹腔镜幽门环肌切开术是一种稳定、可靠的手术,对于治疗先天性肥厚性幽门狭窄的效果满意。  相似文献   
989.
Communication skills training for medical students: an integrated approach   总被引:1,自引:0,他引:1  
Skills of communication are not easily taught to medical students. Three main clinical departments (general practice, medicine and mental health) of the Medical Faculty of the Queen's University, Belfast, introduced an integrated course in January 1988 to teach the basic principles. The course is held at the beginning of clinical training and is an integral part of the introductory clinical course. It was introduced in response to the Report of a Working Party of the Education Committee of the General Medical Council (1987) which advocated the need for improved training in history-taking and communication. It is a 12-week course and every Monday and Friday afternoon from 1400 to 1700 hours 12 students are seconded from ward work, four to the Department of Medicine, four to the Department of General Practice and four to the Department of Mental Health. Hand-outs about information to be obtained and interview style are standardized and the principles to be followed are clearly defined in an aide-mémoire. Staff from the Departments of General Practice and Mental Health experienced in teaching communication by videotape feedback and analysis of consultations prepared 12 tutors for their role and responsibilities. Procedures to be followed were carefully explained to all students beforehand. General practice and psychiatry traditionally have established teaching programmes in communication but the inclusion of the Department of Medicine has made a significant impact. Students have come to realize that the taking of a good history demands as much skill as the physical examination of the patient and is an important aspect of any clinical assessment.  相似文献   
990.
This article investigates the relationship between perceptions of equity, occupational stress and employee commitment in a health care setting. Significant relationships were found among these variables and implications for the health care field are discussed.  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