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   19512篇
  免费   5654篇
  国内免费   37篇
耳鼻咽喉   529篇
儿科学   678篇
妇产科学   788篇
基础医学   444篇
口腔科学   1123篇
临床医学   3967篇
内科学   6647篇
皮肤病学   367篇
神经病学   956篇
特种医学   337篇
外科学   1982篇
综合类   62篇
现状与发展   2篇
一般理论   6篇
预防医学   3886篇
眼科学   336篇
药学   355篇
中国医学   3篇
肿瘤学   2735篇
  2024年   162篇
  2023年   1063篇
  2022年   383篇
  2021年   700篇
  2020年   1233篇
  2019年   452篇
  2018年   1170篇
  2017年   1230篇
  2016年   1464篇
  2015年   1426篇
  2014年   2000篇
  2013年   2239篇
  2012年   794篇
  2011年   768篇
  2010年   1226篇
  2009年   1607篇
  2008年   773篇
  2007年   573篇
  2006年   853篇
  2005年   494篇
  2004年   410篇
  2003年   336篇
  2002年   298篇
  2001年   308篇
  2000年   266篇
  1999年   275篇
  1998年   350篇
  1997年   278篇
  1996年   261篇
  1995年   218篇
  1994年   170篇
  1993年   141篇
  1992年   147篇
  1991年   133篇
  1990年   129篇
  1989年   99篇
  1988年   93篇
  1987年   79篇
  1986年   89篇
  1985年   65篇
  1984年   61篇
  1983年   62篇
  1982年   33篇
  1981年   24篇
  1980年   27篇
  1979年   25篇
  1977年   27篇
  1975年   28篇
  1974年   27篇
  1972年   22篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
53.
54.
Dietary fiber has important health benefits in childhood, especially in promoting normal laxation. Currently, children consume amounts of dietary fiber that appear to be inadequate for optimal health promotion and disease prevention. It is prudent to recommend that children older than 2 years of age increase dietary fiber intake to an amount equal to or greater than their age + 5 g/day. According to the “age + 5” rule dietary fiber intake would increase from 8 g/day at age 3 years to 25 g/day by age 20 years. After age 20, dietary fiber levels of 25 to 35 g/day are recommended. Dietary fiber intake should be increased gradually in childhood by increasing consumption of a variety of fruits, vegetables, legumes, cereals, and other whole-grain products. Although very high fiber intake in childhood could have adverse effects, the potential health benefits of a moderate increase in dietary fiber substantially outweigh the possible risks, especially in highly industrialized countries such as the United States. A safe range of dietary fiber intake for children may be between age + 5 and age + 10 g/day. This range is considered safe even for children and adolescents with marginal intakes of some vitamins and minerals; should provide enough dietary fiber for normal laxation; and may provide enough added dietary fiber to help prevent chronic diseases.J Am Diet Assoc. 1995; 1140-1146, 1149.  相似文献   
55.
56.
Occupational exposure to HIV is becoming a daily hazard in many emergency departments. Emergency physicians who are protected by disability insurance policies are likely to believe that if they are unable to continue working because of HIV-positive status, their disability policies will provide them with a source of income. Unfortunately, analysis of case law regarding claims under disability policies shows that the law is unlikely to consider an asymptomatic, HIV-positive physician disabled for purposes of payments under disability policies. Therefore, it is necessary for emergency physicians to make sure this issue is resolved before buying and relying on a disability policy so that an anticipated safety net will be operative over the full range of hazards that emergency physicians face.[Lavely R: The HIV-positive physician and disability insurance. Ann Emerg Med June 1994;23:1355-1362.]  相似文献   
57.
Whereas abnormalities of the morphological tricuspid valve are common in the setting of discordant atrioventricular connections, there are only a few postmortem reports of abnormalities of the mitral valve in this condition. This report describes two patients with discordant atrioventricular connections, in whom important abnormalities of the mitral valve were found during life by cross sectional echocardiography.  相似文献   
58.
59.
This study was undertaken to explore whether intervention withheparin and aspirin (H/A) in selected patients undergoing in-vitrofertilization (TVF) and embryo transfer could improve fecundityrates. Specifically, it explored the possibility that womendiagnosed with organic pelvic disease who demonstrated antiphospholipidantibodies (APA) could benefit from H/A administration in asimilar manner to that used in patients with recurrent pregnancyloss. We used an enzyme–linked immunosorbent assay forsix different phospholipids to identify patients who expressedAPA before they underwent IVF/embryo transfer. This study wasconfined to the first IVF/embryo transfer cycle that followedassessment of APA status and accordingly, the number of IVF/embryotransfer cycles corresponds with the number of patients treated.APA seropositive patients were treated with aspirin, 81 mg orallyq.d., and heparin 5000 IU s.c. b.i.d., beginning on day 1 ofcontrolled ovarian stimulation. The endpoint for success wasa live birth or an ultrasound confirming fetal cardiac activity(a viable pregnancy). The prevalence of APA in patients diagnosedwith organic pelvic disease (53%) was much higher than in thosewithout female pathology (14%). The administration of H/A toAPA seropositive patients significantly (P < 0.05) improvedthe viable pregnancy rate (49%) compared to the untreated APAseropositive group (16%). The viable pregnancy rate for APAseropositive women treated with H/A was also significantly (P< 0.001) higher than for untreated APA seronegative patients(27%). We conclude that all women undergoing IVF/embryo transfershould be tested for APA prior to initiating ovarian stimulation,and those with APA seropositivity should be treated with H/A.  相似文献   
60.
Many corporations move their manufacturing facilities or technologies from developed to developing countries. Stringent regulations have made it costly for industries to operate in developed, industrialized countries. In addition, labor costs are high in these countries, and there is increasing awareness among the general public of the health risks associated with industry. The relocation of hazardous industries to developing countries is driven by economic considerations: high unemployment, a cheaper labor force, lack of regulation, and poor enforcement of any existing regulations make certain countries attractive to business. The transfer of certain industries from Japan to Korea has also brought both documented occupational diseases and a new occupational disease caused by chemicals without established toxicities. Typical examples of documented occupational diseases are carbon disulfide poisoning in the rayon manufacturing industry, bladder cancer in the benzidine industry, and mesothelioma in the asbestos industry. A new occupational disease due to a chemical without established toxicities is 2‐bromopropane poisoning. These examples suggest that counter‐measures are needed to prevent the transfer of occupational health problems from a developed to a developing country. Corporate social responsibility should be emphasized, close inter‐governmental collaboration is necessary and cooperation among non‐governmental organizations is helpful. Am. J. Ind. Med. 52:625–632, 2009. © 2009 Wiley‐Liss, Inc.  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