全文获取类型
收费全文 | 3006302篇 |
免费 | 241343篇 |
国内免费 | 6126篇 |
专业分类
耳鼻咽喉 | 42956篇 |
儿科学 | 95752篇 |
妇产科学 | 81735篇 |
基础医学 | 426724篇 |
口腔科学 | 86952篇 |
临床医学 | 275260篇 |
内科学 | 583132篇 |
皮肤病学 | 63683篇 |
神经病学 | 249785篇 |
特种医学 | 119223篇 |
外国民族医学 | 1131篇 |
外科学 | 453174篇 |
综合类 | 72401篇 |
现状与发展 | 1篇 |
一般理论 | 1285篇 |
预防医学 | 243886篇 |
眼科学 | 71063篇 |
药学 | 222993篇 |
7篇 | |
中国医学 | 5724篇 |
肿瘤学 | 156904篇 |
出版年
2018年 | 31094篇 |
2016年 | 26716篇 |
2015年 | 30047篇 |
2014年 | 42955篇 |
2013年 | 65749篇 |
2012年 | 87974篇 |
2011年 | 92967篇 |
2010年 | 55127篇 |
2009年 | 52506篇 |
2008年 | 87940篇 |
2007年 | 93592篇 |
2006年 | 94601篇 |
2005年 | 91891篇 |
2004年 | 88899篇 |
2003年 | 85688篇 |
2002年 | 84003篇 |
2001年 | 137801篇 |
2000年 | 142605篇 |
1999年 | 120337篇 |
1998年 | 35021篇 |
1997年 | 31764篇 |
1996年 | 31394篇 |
1995年 | 30431篇 |
1994年 | 28573篇 |
1993年 | 26537篇 |
1992年 | 97279篇 |
1991年 | 94303篇 |
1990年 | 91383篇 |
1989年 | 88104篇 |
1988年 | 81403篇 |
1987年 | 80564篇 |
1986年 | 76136篇 |
1985年 | 72971篇 |
1984年 | 55319篇 |
1983年 | 47197篇 |
1982年 | 28793篇 |
1981年 | 25666篇 |
1980年 | 24045篇 |
1979年 | 51998篇 |
1978年 | 36741篇 |
1977年 | 31069篇 |
1976年 | 29293篇 |
1975年 | 30770篇 |
1974年 | 37907篇 |
1973年 | 36071篇 |
1972年 | 33667篇 |
1971年 | 31256篇 |
1970年 | 29212篇 |
1969年 | 27226篇 |
1968年 | 24878篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
96.
97.
Anuj Shrestha Zeeshan Jawa Kathryn L. Koch Amy B. Rankin Qun Xiang Anand Padmanabhan Matthew S. Karafin Joshua J. Field 《Journal of clinical apheresis》2015,30(6):353-358
Red cell exchange (RCE) is a common procedure in adults with sickle cell disease (SCD). Implantable dual lumen Vortex (DLV) ports can be used for RCE in patients with poor peripheral venous access. We performed a retrospective cohort study of RCE procedures performed in adults with SCD. The main objective of the study was to compare the inlet speed, duration of procedures and rate of complications performed through DLV ports to those performed through temporary central venous and peripheral catheters. Twenty‐nine adults with SCD underwent a total of 318 RCE procedures. Twenty adults had DLV ports placed and 218 procedures were performed using DLV ports. Mean length of follow‐up after DLV port placement was 397 ± 263 days. Six DLV ports were removed due to infection and 1 for malfunction after a mean of 171 ± 120 days. Compared to temporary central venous and peripheral catheters, DLV port procedures had a greater rate of procedural complications, a longer duration, and a lower inlet speed (all P < 0.01). When accounting for the maximum allowable inlet speed to avoid citrate toxicity, 40% of DLV port procedures were greater than 10% below maximum speed, compared to 7 and 14% of procedures performed through temporary central venous and peripheral catheters (P < 0.0001). In conclusion, DLV ports can be used for RCE in adults with SCD, albeit with more procedural complications and longer duration. The smaller internal diameter and longer catheter of DLV ports compared to temporary central venous catheters likely accounts for the differences noted. J. Clin. Apheresis 30:353–358, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
98.
99.
Emma J. Kilford Iroise Dumontheil Nicholas W. Wood Sarah-Jayne Blakemore 《Social cognitive and affective neuroscience》2015,10(6):777-782
The catechol-O-methyltransferase (COMT) enzyme is a major determinant of prefrontal dopamine levels. The Val158Met polymorphism affects COMT enzymatic activity and has been associated with variation in executive function and affective processing. This study investigated the effect of COMT genotype on the flexible modulation of the balance between processing self-generated and processing stimulus-oriented information, in the presence or absence of affective distractors. Analyses included 124 healthy adult participants, who were also assessed on standard working memory (WM) tasks. Relative to Val carriers, Met homozygotes made fewer errors when selecting and manipulating self-generated thoughts. This effect was partly accounted for by an association between COMT genotype and visuospatial WM performance. We also observed a complex interaction between the influence of affective distractors, COMT genotype and sex on task accuracy: male, but not female, participants showed a sensitivity to the affective distractors that was dependent on COMT genotype. This was not accounted for by WM performance. This study provides novel evidence of the role of dopaminergic genetic variation on the ability to select and manipulate self-generated thoughts. The results also suggest sexually dimorphic effects of COMT genotype on the influence of affective distractors on executive function. 相似文献
100.
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