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   238970篇
  免费   73184篇
  国内免费   6501篇
耳鼻咽喉   4072篇
儿科学   7148篇
妇产科学   3390篇
基础医学   26537篇
口腔科学   11016篇
临床医学   44948篇
内科学   55214篇
皮肤病学   10994篇
神经病学   27238篇
特种医学   8533篇
外国民族医学   52篇
外科学   38422篇
综合类   14559篇
现状与发展   60篇
一般理论   40篇
预防医学   21318篇
眼科学   5245篇
药学   14282篇
  68篇
中国医学   5292篇
肿瘤学   20227篇
  2024年   718篇
  2023年   6215篇
  2022年   3251篇
  2021年   8038篇
  2020年   13420篇
  2019年   15153篇
  2018年   17687篇
  2017年   19271篇
  2016年   20064篇
  2015年   21324篇
  2014年   24498篇
  2013年   26561篇
  2012年   13499篇
  2011年   13490篇
  2010年   18670篇
  2009年   16826篇
  2008年   9313篇
  2007年   7427篇
  2006年   8613篇
  2005年   6665篇
  2004年   4929篇
  2003年   4610篇
  2002年   4146篇
  2001年   4295篇
  2000年   3366篇
  1999年   3495篇
  1998年   3064篇
  1997年   2974篇
  1996年   2790篇
  1995年   2428篇
  1994年   1726篇
  1993年   1302篇
  1992年   1255篇
  1991年   1059篇
  1990年   875篇
  1989年   807篇
  1988年   770篇
  1987年   593篇
  1986年   544篇
  1985年   454篇
  1984年   361篇
  1983年   352篇
  1982年   295篇
  1981年   246篇
  1980年   157篇
  1979年   104篇
  1978年   141篇
  1977年   126篇
  1976年   96篇
  1974年   82篇
排序方式: 共有10000条查询结果,搜索用时 3 毫秒
991.
测定了在温度310.65K、323.15K和压力3.13~7.54MPa条件下的气液平衡数据,实验结果与文献值具有较好的一致性。用TRK状态方程对实验所得数据进行关联,取得了较满意的结果。  相似文献   
992.
Objective The effects of a computer-assisted instruction (CAI) tutorial program on learning clinical reasoning skills were compared in undergraduate dietetics students.Design A drill-and-practice program to control for time on task, a tutorial program, and a simulation program, as the test vehicle, were developed. The tutorial and simulation programs presented data on a patient with cardiovascular disease.Setting Subjects were tested in 30 undergraduate dietetics programs.Subjects Participants were 413 undergraduate diet therapy students enrolled in a coordinated program in dietetics (CPD) or a didactic program in dietetics (DPD).Intervention After completion of lectures on cardiovascular disease, subjects were given the drill-and-practice program plus a simulation test (group 1), the tutorial plus a simulation test (group 2), or the simulation test only (group 3).Main outcome measures Scores on the simulation test were compared. Variables included type of CAI, dietetics program, year in school, computer experience, and experience using a medical chart. Mastery of objectives related to lower- and higher-level clinical reasoning skills introduced in the tutorial program was compared.Statistical analysis One-way analysis of variance and Student-Newman Keuls tests were conducted to determine any differences among the three groups. Reliability was determined using the Kuder-Richardson Formula 20.Results The reliability coefficient of the simulation test was 0.93. Group 2 scored higher on the simulation test than group 1 or group 3. As a group, the CPD students scored higher than the DPD students. When CPD and DPD students were divided into the three experimental groups, there was no significant difference between the CPD and DPD student simulation scores. Group 2 mastered all objectives for lower-level reasoning skills and the higher-level decision-making objective better than groups 1 and 3.Applications/conclusions A computer tutorial program enhanced clinical reasoning skills in undergraduate dietetics students. This type of program could be used to supplement many topics taught in diet therapy and provide DPD students with experiential learning before their clinical intern practicums. J Am Diet Assoc. 1995; 95:868–873.  相似文献   
993.
994.
本文在25例(50侧)胎尸标本上对旋股外侧动脉分布、分支类型、管径及其临床应用解剖进行了详细的观察和讨论分析。以期对临床应用有所帮助。  相似文献   
995.
The purpose of this study was to investigate the effects of a physical training course in a group of patients (n=74) suffering from chronic tension neck. All participants in the course were employed by a bank corporation in Helsinki, Finland. A comparable control group (n=77) consisted of office workers with tension neck from the same bank corporation who did not attend any training course. The outcome was analysed 6 months after the course. Pain and disability in the neck and shoulder region did not vary significantly between the group which participated in the training course and the control group. The experimental group had increased the amount of physical workout compared to the control group (83.7% vs 69.0%, P = 0.0448). Also, regarding the frequency of relaxation and stretching exercises the two groups differed significantly: the experimental group had continued to perform exercises more often (P= 0.0434). The frequency of sick leave days did not significantly differ between the groups, but the office workers in the experimental group had more periods of extended sick leave (> 10 days) and the controls had more frequent short sick leaves. The experimental group did increase their physical workout significantly compared with the controls, but no differences were detected regarding pain and disability. In order to gain more benefit more attention should be paid to the educational part of the training courses in order to enhance the patients'self-care abilities. Also, strategies to alleviate psychosocial problems and organized relaxation exercises could decrease muscle tension in the neck in office workers.  相似文献   
996.
The purpose of the present study was to determine whether a hypotonic additive containing a low concentration of glycerol as a membrane permeable solute would improve the liquid storage of red blood cells (RBCs). Packed RBCs were stored either with 200 ml of an experimental additive solution, EAS 25, containing (m M ): glycerol 150, adenine 2, glucose 110, mannitol 55, and NaCl 50, or with 100 ml/unit of a conventional additive solution Adsol®. The results show that the adenosine triphosphate values, hemolysis, potassium leakage, and the morphology scores of RBCs were significantly better with EAS 25 than with Adsol up to 84 days of storage. The ATP values were significantly different only after the first 42 days of storage. The mean corpuscular volumes (MCVs) of the RBCs were significantly higher throughout in the experimental additive accompanied by decreased microvesiculation as compared to Adsol. The total microvesicle membrane protein shed by 100 ml of RBCs was 47.92±12.31 mg in Adsol and 18.96±5.49 mg in EAS 25 (p<0.001). The larger MCVs of the RBCs in EAS 25 may have a favorable effect on maintaining membrane integrity by decreasing the loss of membrane by microvesiculation.  相似文献   
997.
本文研究了丙丁菌发酵法生产丙酮和丁醇的简史、原理、过程,以及载体和培养基的选择方法。  相似文献   
998.
山西省卫Ⅳ项目地区农民因病致贫研究   总被引:4,自引:0,他引:4  
目的 研究项目地区农民因病致贫严重程度及预防措施。方法 利用扩展线性支出系统界定贫困标准,观察因病致贫率并研究因病致贫人群特点。结果 农民因病致贫率3.44%,因病致贫人群收入低,健康状况差,馒性病患病率高。2周就诊和年住院率高,年家庭医疗费用支出远高于对照人群。结论 通过住院医疗保险和慢性病防治措施缓解农民因病致贫。  相似文献   
999.
尿样中加入Triton X-100后,在尿蛋白和其它物质存在下可用可见分光光度法直接而快速地测定尿锌.该法比目前其它方法更简便,尤其适合于临床快速分析.经40例正常人尿锌含量分析,结果((?)±s)为0.789±0.256μg/ml,与文献值基本一致.  相似文献   
1000.
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