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   1799285篇
  免费   123425篇
  国内免费   4755篇
耳鼻咽喉   23195篇
儿科学   58553篇
妇产科学   47667篇
基础医学   275705篇
口腔科学   48056篇
临床医学   171980篇
内科学   339511篇
皮肤病学   37093篇
神经病学   143610篇
特种医学   66300篇
外国民族医学   418篇
外科学   253301篇
综合类   35470篇
现状与发展   3篇
一般理论   579篇
预防医学   148136篇
眼科学   39897篇
药学   133970篇
  7篇
中国医学   4131篇
肿瘤学   99883篇
  2021年   14372篇
  2019年   15062篇
  2018年   21568篇
  2017年   16241篇
  2016年   18138篇
  2015年   20192篇
  2014年   27448篇
  2013年   42378篇
  2012年   58881篇
  2011年   63277篇
  2010年   36547篇
  2009年   32896篇
  2008年   57971篇
  2007年   61938篇
  2006年   61360篇
  2005年   59091篇
  2004年   56810篇
  2003年   54287篇
  2002年   52587篇
  2001年   79040篇
  2000年   81554篇
  1999年   67606篇
  1998年   19190篇
  1997年   17064篇
  1996年   16792篇
  1995年   15929篇
  1994年   14780篇
  1992年   52739篇
  1991年   52897篇
  1990年   51726篇
  1989年   49547篇
  1988年   45722篇
  1987年   44870篇
  1986年   42522篇
  1985年   40698篇
  1984年   30632篇
  1983年   26089篇
  1982年   15246篇
  1979年   28124篇
  1978年   20039篇
  1977年   16347篇
  1976年   16418篇
  1975年   17613篇
  1974年   21027篇
  1973年   20404篇
  1972年   18833篇
  1971年   17771篇
  1970年   16464篇
  1969年   15059篇
  1968年   14367篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
Abstract

Objectives: This study examined word use as an indicator of interpersonal positive reframing in daily conversations of couples coping with breast cancer and as a predictor of stress.

Design: The Electronically Activated Recorder (EAR) and Linguistic Inquiry and Word Count (LIWC) were used to examine naturally occurring word use conceptually linked to positive reframing (positive emotion, negative emotion, and cognitive processing words).

Sample: Fifty-two couples coping with breast cancer.

Methods: Couples wore the EAR, a device participants wear, that audio-recorded over one weekend (>16,000 sound files), and completed self-reports of positive reframing (COPE) and stress (Perceived Stress Scale). LIWC, a software program, measured word use.

Findings: Both partners’ word use (i.e., positive emotion and cognitive processing words) was associated with their own reported positive reframing, and spouses’ word use was also indicative of patients’ positive reframing. Results also revealed that, in general, words indicating positive reframing predicted lower levels of stress.

Conclusions: Findings supported the hypothesis that partners—and particularly spouses of breast cancer patients—may assist each other’s coping by positively reframing the cancer experience and other negative experiences in conversation.  相似文献   
9.

Background

Rosacea is a chronic inflammatory skin condition whose etiology has been linked to mast cells and the antimicrobial peptide cathelicidin LL-37. Individuals with refractory disease have demonstrated clinical benefit with periodic injections of onabotulinum toxin, but the mechanism of action is unknown.

Objectives

To investigate the molecular mechanism by which botulinum toxin improves rosacea lesions.

Methods

Primary human and murine mast cells were pretreated with onabotulinum toxin A or B or control. Mast cell degranulation was evaluated by β-hexosaminidase activity. Expression of botulinum toxin receptor Sv2 was measured by qPCR. The presence of SNAP-25 and VAMP2 was established by immunofluorescence. In vivo rosacea model was established by intradermally injecting LL-37 with or without onabotulinum toxin A pretreatment. Mast cell degranulation was assessed in vivo by histologic counts. Rosacea biomarkers were analyzed by qPCR of mouse skin sections.

Results

Onabotulinum toxin A and B inhibited compound 48/80-induced degranulation of both human and murine mast cells. Expression of Sv2 was established in mouse mast cells. Onabotulinum toxin A and B increased cleaved SNAP-25 and decreased VAMP2 staining in mast cells respectively. In mice, injection of onabotulinum toxin A significantly reduced LL-37-induced skin erythema, mast cell degranulation, and mRNA expression of rosacea biomarkers.

Conclusions

These findings suggest that onabotulinum toxin reduces rosacea-associated skin inflammation by directly inhibiting mast cell degranulation. Periodic applications of onabotulinum toxin may be an effective therapy for refractory rosacea and deserves further study.  相似文献   
10.
Purpose: To study, with computational models, the utility of power modulation to reduce tissue temperature heterogeneity for variable nanoparticle distributions in magnetic nanoparticle hyperthermia.

Methods: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes’ bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods.

Results: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating.

Conclusions: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment.  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