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   68272篇
  免费   7621篇
  国内免费   166篇
耳鼻咽喉   518篇
儿科学   2192篇
妇产科学   1547篇
基础医学   9578篇
口腔科学   1585篇
临床医学   9028篇
内科学   13907篇
皮肤病学   1267篇
神经病学   6085篇
特种医学   2360篇
外国民族医学   5篇
外科学   8252篇
综合类   1355篇
一般理论   31篇
预防医学   7610篇
眼科学   1136篇
药学   5297篇
中国医学   96篇
肿瘤学   4210篇
  2022年   544篇
  2021年   1337篇
  2020年   959篇
  2019年   1554篇
  2018年   1731篇
  2017年   1298篇
  2016年   1428篇
  2015年   1576篇
  2014年   1996篇
  2013年   2797篇
  2012年   3809篇
  2011年   3733篇
  2010年   2232篇
  2009年   2077篇
  2008年   3384篇
  2007年   3466篇
  2006年   3327篇
  2005年   3154篇
  2004年   2936篇
  2003年   2729篇
  2002年   2607篇
  2001年   1750篇
  2000年   1662篇
  1999年   1673篇
  1998年   819篇
  1997年   645篇
  1996年   611篇
  1995年   623篇
  1994年   548篇
  1993年   573篇
  1992年   1289篇
  1991年   1214篇
  1990年   1158篇
  1989年   1113篇
  1988年   1033篇
  1987年   1012篇
  1986年   1040篇
  1985年   951篇
  1984年   831篇
  1983年   694篇
  1982年   493篇
  1981年   417篇
  1980年   380篇
  1979年   614篇
  1978年   519篇
  1977年   411篇
  1976年   430篇
  1974年   470篇
  1973年   424篇
  1972年   410篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
It is well recognized that the world population is ageing rapidly. Therefore, it is important to understand ageing processes at the cellular and molecular levels to predict the onset of age‐related diseases and prevent them. Recent research has focused on the identification of ageing biomarkers, including those associated with the properties of the Golgi apparatus. In this context, Golgi‐mediated glycosylation of proteins has been well characterized. Additionally, other studies show that the secretion of many compounds, including pro‐inflammatory cytokines and extracellular matrix–degrading enzymes, is modified during ageing, resulting in physical and functional skin degradation. Since the Golgi apparatus is a central organelle of the secretory pathway, we investigated its structural organization in senescent primary human dermal fibroblasts using confocal and electron microscopy. In addition, we monitored the expression of Golgi‐related genes in the same cells. Our data showed a marked alteration in the Golgi morphology during replicative senescence. In contrast to its small and compact structure in non‐senescent cells, the Golgi apparatus exhibited a large and expanded morphology in senescent fibroblasts. Our data also demonstrated that the expression of many genes related to Golgi structural integrity and function was significantly modified in senescent cells, suggesting a relationship between Golgi apparatus function and ageing.  相似文献   
3.
ABSTRACT

Close observation of the interactions between a traumatised mother and her infant son provides information on the modes of transmission of psychic trauma in the mother–infant dyad. Following the presentation of a current literature review on the theme, the subject of “radioactive residue” and counter-transference in the transmission of psychic trauma from mother to infant will be illustrated through a clinical case study that focuses on a Haitian mother and her two-year-old infant son who has been referred to a “transitional care nursery” in urban Paris. The encounter with this mother–infant dyad is analysed through observing the quality of the interactions that take place between the mother and infant in order to determine how a particularly traumatic narrative impacts the mother–infant relationship, in addition to relations with the clinician. Mother and infant respond to one another through the emission and reception of “radioactive residues” as hypothesized by Gampel. This clinical case study shows that there is a need to consider transcultural factors and collective experience and history when analysing traumatic events. Additionally, the case study shows that counter-transference can be an effective clinical tool for gaining access to an infant's experience as the recipient of a traumatic narrative.  相似文献   
4.
5.
6.
7.
8.
9.

Purpose

This study aimed to investigate 3 planning target volume (PTV) margin expansions and determine the most appropriate volume to be used in bladder preservation therapy when using daily cone beam computed tomography (CBCT). We aimed to establish whether a smaller PTV expansion is feasible without risking geographical miss.

Methods and materials

The study included patients with bladder cancer who were treated with a hypofractionated course of radiation therapy delivered with intensity modulated radiation therapy. The clinical target volume (CTV) was the whole empty bladder, and the PTV consisted of a 1.5-cm margin around the bladder (PTV1.5 cm). Patients underwent daily CBCT imaging before treatment to assess the bladder volume and ensure accurate positioning. We investigated 2 additional smaller PTV margin expansions to determine the most appropriate volume to be used with CBCT as a daily image guided radiation therapy modality. These margins were created retrospectively on every CBCT. The first additional volume was a uniform PTV margin of the surrounding 1 cm (PTV1 cm). When considering that the majority of the internal bladder movement was due to the variation in filling that occurs in the superior and anterior directions, a second volume of an anisotropic PTV margin with a 1.5-cm superior/anterior and 1 cm in other directions (PTV1/1.5 cm) was created. We recorded the frequency and measured the volume of bladder falling out of each PTV based on the daily CBCT.

Results

For the purpose of this study, we considered an arbitrary 5 cm3 of CTV falling out of the designated PTV as a clinically significant volumetric miss. The frequency of such a miss when applying the uniform PTV1 cm was 1%. However, when applying the uniform PTV1.5 cm and anisotropic PTV1/1.5 cm margins, the frequency was 0.5% and 0.5%, respectively.

Conclusions

The anisotropic PTV expansion of 1.5 cm superiorly and anteriorly and 1 cm in all other directions around the bladder (CTV) provides a safe PTV approach when daily CBCT imaging is used to localize an empty bladder.  相似文献   
10.
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