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   387590篇
  免费   21453篇
  国内免费   15310篇
耳鼻咽喉   3004篇
儿科学   8705篇
妇产科学   5922篇
基础医学   42243篇
口腔科学   5201篇
临床医学   42641篇
内科学   62111篇
皮肤病学   2854篇
神经病学   28242篇
特种医学   16996篇
外国民族医学   138篇
外科学   49659篇
综合类   37219篇
现状与发展   55篇
一般理论   19篇
预防医学   30607篇
眼科学   9376篇
药学   31697篇
  192篇
中国医学   12842篇
肿瘤学   34630篇
  2024年   570篇
  2023年   3155篇
  2022年   7872篇
  2021年   11448篇
  2020年   8517篇
  2019年   7535篇
  2018年   29167篇
  2017年   23883篇
  2016年   25548篇
  2015年   11081篇
  2014年   13286篇
  2013年   11391篇
  2012年   22704篇
  2011年   38341篇
  2010年   28827篇
  2009年   19413篇
  2008年   30218篇
  2007年   32397篇
  2006年   11661篇
  2005年   13388篇
  2004年   10215篇
  2003年   10805篇
  2002年   7875篇
  2001年   5179篇
  2000年   5736篇
  1999年   5826篇
  1998年   3696篇
  1997年   3675篇
  1996年   2893篇
  1995年   2701篇
  1994年   2234篇
  1993年   1431篇
  1992年   1925篇
  1991年   1676篇
  1990年   1409篇
  1989年   1164篇
  1988年   1064篇
  1987年   894篇
  1986年   736篇
  1985年   553篇
  1984年   353篇
  1983年   261篇
  1982年   173篇
  1981年   145篇
  1980年   150篇
  1979年   144篇
  1975年   62篇
  1974年   75篇
  1938年   64篇
  1932年   57篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
在饲料中加入氨基比林和NaNO_2各2g/kg饲与Wistar大鼠38周后诱发出肝、肺及肾脏肿瘤,其中以肝肿瘤的发生率为100%(17/17),大鼠平均寿命195天。而同时给予沙棘汁饮用的大鼠其肿瘤发生较晚,发癌率较低(88%,15/17),平均寿命270天,显著长于对照组和单纯抗坏血酸组(P<0.01),且肝脏癌变范围较小,病变较轻。结果表明,沙棘汁能有效地阻断N-亚硝基化合物在大鼠体内合成及诱癌,其防癌效果优于等量的抗坏血酸。  相似文献   
992.

Background  

Recently, hyperbaric oxygen therapy (HBOT) has increased in popularity as a treatment for autism. Numerous studies document oxidative stress and inflammation in individuals with autism; both of these conditions have demonstrated improvement with HBOT, along with enhancement of neurological function and cognitive performance. In this study, children with autism were treated with HBOT at atmospheric pressures and oxygen concentrations in current use for this condition. Changes in markers of oxidative stress and inflammation were measured. The children were evaluated to determine clinical effects and safety.  相似文献   
993.

Background  

Cardiovascular disease remains the leading killer of women in most developed areas of the world. Rates of physical inactivity and poor nutrition, which are two of the most important modifiable risk factors for cardiovascular disease in women, are substantial. This study sought to examine the effectiveness of a community-based lifestyle-modification program on increasing women's physical activity in a randomized trial guided by community-based participatory research (CBPR) methods.  相似文献   
994.
This paper provides new evidence on the degree of income-related inequality in self-assessed health in Belgium. First of all, we combine the time dimension, which has been shown to be very important in the analysis of inequality, and the use of the recently developed interval regression approach to transform a categorical health variable in a continuous one. Second, we measure how the long-run inequality differs from the short-run inequality. Finally, we decompose this health-related income mobility index as well as the long-run concentration index (CI) itself into its contributors. Using data from the panel survey of Belgian households (1994–2002), we find that health is pro-rich distributed and that its inequality is underestimated by 9.45% when neglecting the dynamics of individuals over time. Income, education, job status and age are the most important contributors in the CI and the difference between the short-run and long-run inequality.   相似文献   
995.
We compared the Acrysoft monofocal intraocular lens (IOL) in the mini monovision formula (n = 20) with the Array multifocal intraocular lens (n = 20) for glasses independence after cataract surgery. The Acrysoft monofocal IOL group showed similar and even slightly better results than the Array multifocal IOL group. The monofocal Acrysoft IOL using the mini monovision (blended vision) formula is a good alternative for providing post-cataract surgery glasses independence. Drs. Chen, Clinical Assistant Professor of Ophthalmology and Neal H. Atebara are at University of Hawaii School of Medicine, Honolulu, Hawaii, USA. Dr. Te Tsaw Chen, Past Professor & Director, was at Department of Ophthalmology, Taipei Medical University, Taipei, ROC. The authors have stated that they do not have a significant financial interest or other relationship with any product manufacturer or provider of services discussed in this article. The authors also do not discuss the use of off-label products, which includes unlabeled, unapproved, or investigative products or devices. The authors compared the Acrysoft monofocal intraocular lens in the mini monovision formula to the Array multifocal intraocular lens for glasses independence after cataract surgery.  相似文献   
996.
Ten bulls (age 7 months, weight 302 ± 15 kg) were used in this study. After sterile preparation of skin, a full thickness wound (20 × 20 mm) was created in each bull. The bulls were randomly assigned into two groups: group 1 received 6 ml Theranekron subcutaneously and group 2 penicillin banzatine 10,000 IU/kg IM. These doses were repeated 6 days after initial wounding. At days 0, 3, 6, 10 and 14, digital photographs were taken from the wounds to calculate wound contraction and epithelialization using geometry. Chi-square test was performed for statistical analysis using SPSS 9 for Windows. There was no significant differences in wound contraction between trial groups (P > 0.05) but a statistical difference was seen in epithelialization between groups (P < 0.05). Epithelialization is one of the most important factors in wound healing. According to the results of the present study, Theranekron can significantly stimulate epithelialization in full thickness wounds in cows during the first 14 days of healing.  相似文献   
997.
Objective: 5-Aminoisoquinolinone, a water-soluble, potent inhibitor of the activity of poly (adenosine 5'-diphosphate ribose) polymerase, plays an important role in the tissue injury associated with ischaemia-reperfusion injury and inflammation by inhibiting the activity of poly (adenosine 5'-diphosphate ribose) polymerase and the expression of cell adhesion molecules such as ICAM-1, P-selectin et al. But how about it in the tumor is not clear. The aim of the present study was to study the effects of 5-Aminoisoquinolinon on the adhesion of colon carcinoma line HT-29 cells to human umbilical vein endothelial cells; and the effects of 5-Aminoisoquinolinon on the expression of ICAM-1, P-selectin and the activity of poly (adenosine 5'-diphosphate ribose) polymerase in colon carcinoma HT-29 cells. Methods: The adhesion of HT-29 cells to human umbilical vein endothelial cells was detected by adhesive experiment. Immunocytochemically Streptavidin-Peroxidase method was used to investigate the expression of ICAM-1, P-selectin and Poly (adenosine 5'-diphosphate ribose)( the product of poly (adenosine 5'-diphosphate ribose) polymerase activation). Results: the results of the adhesion assay of HT-29 cells to HUVEC showed that the OD570 value in each 5-AIQ-treated group was significant lower than that in the control group (5-AIQ-untreated) in a dose-dependent manner. The expression of ICAM-1, P-selectin and Poly (adenosine 5'-diphosphate ribose) was significant lower in 5-Aminoisoquinolinone-treated HT-29 cell group than that in 5-Aminoisoquinolinoneuntreated groups. Conclusion: The data suggest that 5-Aminoisoquinolinone can inhibit the adhesion of HT-29 cells to human umbilical vein endothelial cells. 5-Aminoisoquinolinone also can inhibit poly (adenosine 5'-diphosphate ribose) polymerase activation and the expressions of ICAM-1 and P-selectin in HT-29 cells. 5-Aminoisoquinolinone probably contributes to the prevention of tumor cell metastasis. Further study is needed.  相似文献   
998.
刘莉  李霁 《中医药信息》2005,22(5):11-13
从糖尿病合并冠心病的流行病学、病理基础、发病机理及临床、治疗五个方面论述了糖尿病合并冠心病的现代基础研究,并对其中西医结合治疗提出了方法.  相似文献   
999.
1000.
本实验观察了0. 25、0. 5、1. 0、2. 0、3. 0和4. 0Gy全身照射后3至6 h羊红细胞(SRBC)免疫对小鼠脾脏抗体形成细胞(PFC)的影响。结果发现,各剂量照射后,免疫与照射的时间间隔较长者,辐射对PFC反应的抑制显著加深。照射后3及6h免疫,脾脏PFC反应均随照射剂量的增加而降低。照射后3h免疫时,PFC反应的D_(37)值为4. 13Gy;照射后6h免疫时,PFC反应的D_(37)值为1. 74Gy。  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