全文获取类型
收费全文 | 2153912篇 |
免费 | 165753篇 |
国内免费 | 4343篇 |
专业分类
耳鼻咽喉 | 29257篇 |
儿科学 | 65978篇 |
妇产科学 | 59168篇 |
基础医学 | 305991篇 |
口腔科学 | 61606篇 |
临床医学 | 191426篇 |
内科学 | 426771篇 |
皮肤病学 | 48607篇 |
神经病学 | 174130篇 |
特种医学 | 82885篇 |
外国民族医学 | 538篇 |
外科学 | 332919篇 |
综合类 | 46791篇 |
现状与发展 | 4篇 |
一般理论 | 683篇 |
预防医学 | 160230篇 |
眼科学 | 49247篇 |
药学 | 157717篇 |
4篇 | |
中国医学 | 4855篇 |
肿瘤学 | 125201篇 |
出版年
2019年 | 16034篇 |
2018年 | 23121篇 |
2017年 | 17800篇 |
2016年 | 19962篇 |
2015年 | 22506篇 |
2014年 | 31366篇 |
2013年 | 46719篇 |
2012年 | 63395篇 |
2011年 | 66863篇 |
2010年 | 39431篇 |
2009年 | 37868篇 |
2008年 | 63180篇 |
2007年 | 66621篇 |
2006年 | 67699篇 |
2005年 | 65535篇 |
2004年 | 62820篇 |
2003年 | 60188篇 |
2002年 | 58486篇 |
2001年 | 114407篇 |
2000年 | 117369篇 |
1999年 | 97469篇 |
1998年 | 25543篇 |
1997年 | 22822篇 |
1996年 | 22980篇 |
1995年 | 21708篇 |
1994年 | 19811篇 |
1993年 | 18501篇 |
1992年 | 74016篇 |
1991年 | 70831篇 |
1990年 | 68142篇 |
1989年 | 65660篇 |
1988年 | 60144篇 |
1987年 | 58693篇 |
1986年 | 54656篇 |
1985年 | 52379篇 |
1984年 | 38744篇 |
1983年 | 32655篇 |
1982年 | 18644篇 |
1981年 | 16419篇 |
1979年 | 34145篇 |
1978年 | 23530篇 |
1977年 | 19839篇 |
1976年 | 18043篇 |
1975年 | 19025篇 |
1974年 | 23088篇 |
1973年 | 22085篇 |
1972年 | 20786篇 |
1971年 | 19225篇 |
1970年 | 18330篇 |
1969年 | 17091篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
75.
76.
77.
78.
Krishna Pillai Javid Akhter Terence C. Chua Mena Shehata Nayef Alzahrani Issan Al-Alem David L. Morris 《Medicine》2015,94(9)
Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices.With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored.With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres.Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected.Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5.MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink. 相似文献
79.
B.B. Damian T.C.S. Bonetti D.D.G. Horovitz 《Brazilian journal of medical and biological research》2015,48(1):25-33
Preimplantation genetic diagnosis (PGD) was originally developed to diagnose
embryo-related genetic abnormalities for couples who present a high risk of a
specific inherited disorder. Because this technology involves embryo selection, the
medical, bioethical, and legal implications of the technique have been debated,
particularly when it is used to select features that are not related to serious
diseases. Although several initiatives have attempted to achieve regulatory
harmonization, the diversity of healthcare services available and the presence of
cultural differences have hampered attempts to achieve this goal. Thus, in different
countries, the provision of PGD and regulatory frameworks reflect the perceptions of
scientific groups, legislators, and society regarding this technology. In Brazil,
several texts have been analyzed by the National Congress to regulate the use of
assisted reproduction technologies. Legislative debates, however, are not conclusive,
and limited information has been published on how PGD is specifically regulated. The
country requires the development of new regulatory standards to ensure adequate
access to this technology and to guarantee its safe practice. This study examined
official documents published on PGD regulation in Brazil and demonstrated how little
direct oversight of PGD currently exists. It provides relevant information to
encourage reflection on a particular regulation model in a Brazilian context, and
should serve as part of the basis to enable further reform of the clinical practice
of PGD in the country. 相似文献
80.
Past research suggests that as many as 50% of onward human immunodeficiency virus (HIV) transmissions occur during acute and recent HIV infection. It is clearly important to develop interventions which focus on this highly infectious stage of HIV infection to prevent further transmission in the risk networks of acutely and recently infected individuals. Project Protect tries to find recently and acutely infected individuals and prevents HIV transmission in their risk networks. Participants are recruited by community health outreach workers at community-based HIV testing sites and drug users' community venues, by coupon referrals and through referrals from AIDS clinics. When a network with acute/recent infection is identified, network members are interviewed about their risky behaviors, network information is collected, and blood is drawn for HIV testing. Participants are also educated and given prevention materials (condoms, syringes, educational materials); HIV-infected participants are referred to AIDS clinics and are assisted with access to care. Community alerts about elevated risk of HIV transmission are distributed within the risk networks of recently infected. Overall, 342 people were recruited to the project and screened for acute/recent HIV infection. Only six index cases of recent infection (2.3% of all people screened) were found through primary screening at voluntary counseling and testing (VCT) sites, but six cases of recent infection were found through contact tracing of these recently infected participants (7% of network members who came to the interview). Combining screening at VCT sites and contact tracing the number of recently infected people we located as compared to VCT screening alone. No adverse events were encountered. These first results provide evidence for the theory behind the intervention, i.e., in the risk networks of recently infected people there are other people with recent HIV infection and they can be successfully located without increasing stigma for project participants. 相似文献