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   8665篇
  免费   629篇
  国内免费   23篇
耳鼻咽喉   42篇
儿科学   252篇
妇产科学   248篇
基础医学   1317篇
口腔科学   181篇
临床医学   1017篇
内科学   1668篇
皮肤病学   240篇
神经病学   1156篇
特种医学   218篇
外科学   699篇
综合类   67篇
一般理论   9篇
预防医学   794篇
眼科学   300篇
药学   530篇
中国医学   20篇
肿瘤学   559篇
  2023年   78篇
  2022年   118篇
  2021年   206篇
  2020年   185篇
  2019年   215篇
  2018年   272篇
  2017年   212篇
  2016年   223篇
  2015年   271篇
  2014年   300篇
  2013年   456篇
  2012年   733篇
  2011年   718篇
  2010年   374篇
  2009年   339篇
  2008年   642篇
  2007年   590篇
  2006年   548篇
  2005年   519篇
  2004年   481篇
  2003年   447篇
  2002年   434篇
  2001年   64篇
  2000年   38篇
  1999年   62篇
  1998年   83篇
  1997年   72篇
  1996年   66篇
  1995年   45篇
  1994年   51篇
  1993年   41篇
  1992年   28篇
  1991年   23篇
  1990年   17篇
  1989年   15篇
  1988年   15篇
  1987年   19篇
  1986年   19篇
  1985年   17篇
  1984年   21篇
  1983年   16篇
  1982年   23篇
  1980年   16篇
  1978年   22篇
  1977年   14篇
  1976年   12篇
  1975年   12篇
  1971年   12篇
  1970年   10篇
  1968年   10篇
排序方式: 共有9317条查询结果,搜索用时 15 毫秒
991.
Background: The aim of the present study is to evaluate the periodontal clinical and microbiologic responses and possible adverse effects of clarithromycin (CLM) combined with periodontal mechanical therapy in the treatment of patients with generalized aggressive periodontitis. Methods: Forty patients were selected and randomly assigned into one of two groups: 1) CLM (n = 20): one‐stage full‐mouth ultrasonic debridement (FMUD) associated with CLM (500 mg, every 12 hours for 3 days); and 2) placebo (n = 20): FMUD associated with placebo pills. Clinical and microbiologic parameters were evaluated at baseline and 3 and 6 months postoperatively. Results: Both treatments presented statistically significant clinical and microbiologic improvements. However, the CLM group presented lower means of probing depth for pockets ≥7 mm at 6 months (4.0 ± 1.7 mm) compared with the placebo group (4.7 ± 1.3 mm) (P = 0.04). In addition, the CLM group also presented greater reduction of Porphyromonas gingivalis (Pg) DNA counts at 6 months (P = 0.0001). Conclusion: Results from this study suggest both treatments are effective; however, adjunct use of CLM to FMUD leads to better reduction of deep pockets and Pg at 6 months compared with FMUD alone.  相似文献   
992.

Statement of problem

Oral metal exposure has been associated with systemic and local adverse reactions, probably due to elemental release from the alloys. Although supraphysiological concentrations of salts from dentally applied metals can activate innate cells through TLR4 (Ni, Co, Pd) and TLR3 (Au), whether direct exposure to solid alloys can also trigger innate immune reactivity is still unknown.

Purpose

The purpose of this in vitro study was to determine whether dental cast alloy specimens can activate innate cells and influence their responsiveness to bacterial endotoxin.

Material and methods

Human monocyte-derived dendritic cells (MoDC) and THP-1 cells were cultured on top of different alloy specimens (Ni-Cr, Co-Cr, Pd-Cu, Pd-Ag, Ti-6Al-4V, amalgam, gold, and stainless steel) or in alloy-exposed culture medium with or without endotoxin (lipopolysaccharide [LPS]; Escherichia coli 055:B5). Interleukin-8 (IL-8) production was used as the parameter for innate stimulation and evaluated by enzyme-linked immunosorbent assay after 24 hours of culture. The statistical significance of the effects of various casting alloys on the secretion of IL-8 was analyzed by using the nonparametric Wilcoxon rank sum test (α=.05).

Results

Dental cast alloys induced IL-8 production in MoDC and THP-1 cells, with Au and Pd-Cu providing the strongest stimulation. The alloy-exposed culture media tested contained sufficient stimulatory metal ions to induce detectable IL-8 production in THP-1 cells, except for the Ni-Cr and stainless steel exposed media. Au and Pd-Cu alloys were also most effective in potentiating LPS responsiveness as measured by IL-8 production.

Conclusions

Using an in vitro culture system to expose MoDC and THP-1 cells to different alloy specimens this study showed that contact with the solid alloys, in particular when they contain Pd or Au, can trigger innate immune responses and augment responsiveness to bacterial endotoxin.  相似文献   
993.

Objectives

To review the past 10 years of research in the diagnostic accuracy of magnetic resonance imaging (MRI) and clinical signs of temporomandibular joint (TMJ) disorders with pain, sound, and function limitation in the existing literature.

Methods

A review of the literature was performed to search for all articles published between 2006 and 2016, and those that met the selection criteria were examined.

Results

The MRI results ranged from 25.3 to 69% for findings in TMJ with sound, 17–74.5% for findings in TMJ with function limitation, and 13.3–77% for findings in TMJ with pain. The reasons for the TMJ symptoms were variable and MRI findings for temporomandibular disorders were seen in asymptomatic patients as well as symptomatic patients. No singular outcome measure can be suggested as a predictor for TMJ symptoms on MRI images.

Conclusions

To increase study comparability with MRI, a standardized terminology and evidence-based guidelines are required for correlations of clinical symptoms and MRI findings.
  相似文献   
994.
995.
996.
Long‐term proliferating, DHJH‐rearranged mouse precursor B‐cell lines have previously been established in serum‐ and IL‐7‐containing media from fetal liver, but not from bone marrow. Serum and stromal cells expose these pre‐B cells to undefined factors, hampering accurate analyses of ligand‐dependent signaling, which controls pre‐B cell proliferation, survival, residence and migration. Here, we describe a novel serum‐free, stromal cell‐free culture system, which allows us to establish and maintain pre‐B cells not only from fetal liver, but also from bone marrow with practically identical efficiencies in proliferation, cloning and differentiation. Surprisingly, recombinant kit‐ligand, also called stem cell factor, produced as a kit‐ligand‐Fc fusion protein, suffices to replace stromal cells and serum, provided that it is presented to cultured pre‐B cells in an optimal density in plate‐bound, insolubilized, potentially crosslinking form. Additional recombinant CXCL12 and fibronectin have a minor influence on the establishment and maintenance of pre‐B cell lines and clones from fetal liver, but are necessary to establish such cell lines from bone marrow.  相似文献   
997.
998.
999.
The aims of this study were to test the reproducibility of the 6-minute stepper test (6MST), and evaluate its accuracy in detecting improved functional capacity after pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD). Thirty-five COPD outpatients performed two 6MSTs in the same session, before (6MST1 and 6MST2) and after (6MST3 and 6MST4) PR. The performance, perceived exertion, heart rate and arterial oxygen saturation were measured during each 6MST. The performance was higher during the second 6MST of the same session (before PR: 514 strokes during the 6MST2 > 471 strokes during the 6MST1, and after PR: 559 strokes during the 6MST4 > 508 strokes during the 6MST3; p = 0.04). After PR, 6MST performance was higher than before PR (6MST3 > 6MST1 and 6MST4 > 6MST2; P < 0.01). The bias (the difference in the number of strokes) between the two 6MSTs from the same session (before PR: 6MST2-6MST1 = 42 strokes vs after PR: 6MST4-6MST3 = 52 strokes) was not different (P = 0.34). However, both bias were greater than 0 (P < 0.001). The mean performances for the two 6MSTs of the same session (before PR: 6MST1 and 6MST2 and after PR: 6MST3 and 6MST4) were correlated with the bias between these performances (< 0.01; r = 0.32). The perceived exertions were lower after PR (P < 0.02). The systematic improvement of performance (8–10%) during the second 6MST of the each session may be explained from the warming of hydraulic jacks of the stepper and/or learning effect. On the other hand, the 6MST seems sufficiently sensitive to detect functional capacity improvements after PR in patients with COPD.  相似文献   
1000.
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