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   4577篇
  免费   178篇
  国内免费   17篇
耳鼻咽喉   113篇
儿科学   115篇
妇产科学   211篇
基础医学   524篇
口腔科学   15篇
临床医学   310篇
内科学   1306篇
皮肤病学   100篇
神经病学   282篇
特种医学   82篇
外科学   585篇
综合类   40篇
一般理论   1篇
预防医学   263篇
眼科学   69篇
药学   371篇
中国医学   4篇
肿瘤学   381篇
  2023年   23篇
  2022年   115篇
  2021年   204篇
  2020年   60篇
  2019年   92篇
  2018年   115篇
  2017年   86篇
  2016年   104篇
  2015年   122篇
  2014年   161篇
  2013年   211篇
  2012年   359篇
  2011年   409篇
  2010年   186篇
  2009年   108篇
  2008年   291篇
  2007年   359篇
  2006年   323篇
  2005年   310篇
  2004年   325篇
  2003年   328篇
  2002年   236篇
  2001年   27篇
  2000年   14篇
  1999年   21篇
  1998年   21篇
  1997年   26篇
  1996年   11篇
  1995年   15篇
  1994年   7篇
  1993年   19篇
  1992年   7篇
  1991年   2篇
  1990年   7篇
  1989年   6篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   9篇
  1983年   3篇
  1982年   3篇
  1981年   6篇
  1980年   4篇
  1979年   3篇
  1977年   3篇
  1976年   3篇
  1974年   3篇
  1970年   2篇
  1969年   3篇
排序方式: 共有4772条查询结果,搜索用时 31 毫秒
61.
62.
63.
Background and Aim: A systematically developed and evaluated instrument is needed to support investigations of physiotherapists’ clinical reasoning integrated with the process of clients’ behavior change. This study’s aim was to develop an instrument to assess physiotherapy students’ and physiotherapists’ clinical reasoning focused on clients’ activity-related behavior and behavior change, and initiate its evaluation, including feasibility and content validity. Methods: The study was conducted in three phases: 1) determination of instrument structure and item generation, based on a model, guidelines for assessing clinical reasoning, and existing measures; 2) cognitive interviews with five physiotherapy students to evaluate item understanding and feasibility; and 3) a Delphi process with 18 experts to evaluate content relevance. Results: Phase 1 resulted in an instrument with four domains: Physiotherapist; Input from client; Functional behavioral analysis; and Strategies for behavior change. The instrument consists of case scenarios followed by items in which key features are identified, prioritized, or interpreted. Phase 2 resulted in revisions of problems and approval of feasibility. Phase 3 demonstrated high level of consensus regarding the instrument’s content relevance. Conclusions: This feasible and content-validated instrument shows potential for use in investigations of physiotherapy students’ and physiotherapists’ clinical reasoning, however continued development and testing are needed.  相似文献   
64.
Background: Glaucoma is characterized by optic neuropathy of the retinal ganglion cell. It may be possible that β-amyloid (Aβ) and apolipoprotein E (APOE), the main proteins of the pathogenesis of AD, play a role in glaucoma development. The aim of this study was to evaluate a relationship between the APP and APOE gene polymorphisms and the risk of primary open-angle glaucoma (POAG) occurrence.

Materials and methods: The study consisted of 183 patients with POAG and 209 healthy subjects. Genomic DNA was extracted from peripheral blood. Analysis of the gene polymorphisms was performed using PCR-RFLP.

Results: We found a statistically significant increase of the -491?T allele frequency (p?=?0.02; OR?=?1.48; 95% CI?=?1.06–2.08) of APOE in POAG compared to healthy controls. There were no differences in the genotype and allele distributions and odds ratios of the APP polymorphism between patients and controls group. We also found an association between APOE polymorphic variant and retinal nerve fiber layer (RNFL). There was a statistically significant difference in the APOE gene A/T genotype frequency in the early POAG stage and middle-advanced POAG stage in comparison to the advanced POAG stage (p?=?0.04; OR?=?3.38; 95% CI?=?1.04–10.97).

Conclusions: The -491?T allele of APOE polymorphism may be associated with a risk of POAG occurrence in the Polish population.  相似文献   
65.
The electrochemical and corrosion (uniform and localized) behavior of a binary Ni52Ti48 shape memory alloy (SMA) and two ternary Ni52Ti48−xCox (x = 1.5 and 4.0 wt%) SMAs were studied. Measurements were conducted in 0.9% NaCl solution at 37 °C employing various electrochemical methods. These include: linear polarization resistance (LPR), linear sweep voltammetry (LSV), chronoamperometry and dynamic electrochemical impedance spectroscopy (DEIS). Such measurements were complemented with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. Results revealed that the addition of alloyed Co to NiTi significantly reduced the uniform corrosion rate of the studied SMA and greatly enhanced its pitting corrosion resistance. XPS measurements evidenced high stability of the passive layer and limited adsorption of chloride ions. Additionally, it was found that the passive layer remained primarily composed of titanium oxides. Microstructure changes accompanying the addition of Co were also used to account for its role in improving the corrosion resistance of these materials.

The electrochemical and corrosion (uniform and localized) behavior of a binary Ni52Ti48 shape memory alloy (SMA) and two ternary Ni52Ti48−xCox (x = 1.5 and 4.0 wt%) SMAs were studied.  相似文献   
66.
67.
68.
Objective: Asthma Call-back Survey methodology has been changed recently, as a new sampling design, weights calculation (2011–2012), and revised work-related asthma (WRA) section (2012) were implemented. To assess the effect of these changes on the WRA and possible WRA estimates among ever-employed adults with current asthma, we analyzed 2007–2012 data for 37?505 ever-employed adults (≥18 years) collected from 19 US states (representing an estimated 10 million adults each year). Methods: Using data from landline telephone (LLP) households, we calculated estimates applying poststratification weights (2007–2010) and “raking” weights (2011–2012). Also, using data from LLP/cellular telephone (CP) households combined, we calculated estimates applying “raking” weights (2012). Results: Based on LLP household data, the WRA estimates ranged from 7.8% to 9.7% during 2007–2010, was 9.1% in 2011 and 15.4% in 2012. Possible WRA estimates ranged from 35.1% to 38.1% during 2007–2010, was 38.1% in 2011 and 39.8% in 2012. Using the 2012 LLP/CP household data, the WRA and possible WRA estimates were 15.4% and 38.9%, respectively. Conclusions: Implementation of “raking” weights did not substantially change the WRA or possible WRA estimates among ever-employed adults with current asthma. The WRA and possible WRA estimates based on LLP and LLP/CP samples in 2012 were comparable, as CP users are younger and less likely to have WRA. The substantial upward shift in the 2012 WRA estimates likely was associated with the revision to the WRA section.  相似文献   
69.
The objective of the paper was compare the effects and tolerability of combined therapy of multiple intravenous infusions of anti-tumour necrosis factor-alfa (TNF-alfa) monoclonal antibody (Remicade) with methotrexate versus treatment with sodium aurothiomalate and intramuscular depot methylprednisolone in rheumatoid arthritis (RA). We investigate also the interval necessary to obtain the improvement in both treatment groups. 36 patients commencing intramuscular sodium aurothiomalate therapy with intramuscular depot methylprednisolone acetate at weeks 0, 4, 8 and 12 in addition to chrysotherapy were compared in retrospective analysis with 32 patients starting with multiple intravenous infusions of infliximab, anti-TNF-alfa monoclonal antibody (Remicade) and methotrexate at a stable dose. Patients were assessed by composite clinical score (DAS 28) and C-reactive protein during 22 weeks of therapy. At week 2 and 6 a significantly greater percentage of infliximab-treated than gold-treated RA patients achieved improvement in each clinical measurement of disease activity. At 22 week of treatment moderate and good response according to EULAR criteria was achieved in 91% of infliximab-treated patients and 58% gold treated patients (p < 0.001). Adverse events were more frequently observed in infliximab-treated patients, but only gold-treated patients discontinued treatment because adverse events (2 patients due to proteinuria, 2 patients due to mucocutaneous changes and one patient due to leucopenia). The higher percentage of adverse events in infliximab-treated patients was caused mainly by the occurrence of infusion reactions (23 reactions out of 160 infusions); most of them were mild (somnolentia and headache) and transient. Viral infections (including herpes simplex and zoster) were more common in patients treated with infliximab and methotrexate. Combination therapy of infliximab and methotrexate is more effective in reducing clinical and biochemical disease activity than gold with methylprednisolone treatment in RA patients during 22 weeks of treatment, especially in the first 6 weeks.  相似文献   
70.
Gil RJ  Gziut AI  Prati F  Witkowski A  Kubica J 《Kardiologia polska》2005,63(3):223-31; discussion 232-3
INTRODUCTION: The left main coronary stem (LMS) provides blood supply to the left ventricle, and its stenosis is associated with serious clinical consequences. The accurate assessment of LMS stenosis determines appropriate treatment and long term prognosis. So far no criteria have been established to correctly estimate the magnitude of problematic lesions as indicated by quantitative angiography (QCA). AIM: An attempt to establish intracoronary ultrasound (ICUS) threshold values of significant LMS stenosis. METHODS: The studied group consisted of 197 patients (mean age 69.72+/-8.51) who underwent percutaneous coronary intervention (PCI) of the left coronary artery. Group 1 (G1) consisted of 99 patients who had LMS diameter reduction (%DS) of less than 30%. Group 2 (G2) consisted of 77 patients with %DS between 30% and 50%, and the remaining 21 patients with %DS higher than 50% were classified as Group 3 (G3). The quantitative angiography (QCA) analysis included lumen diameter (Ldmin) which was LMS lumen diameter at the most stenotic segment as well as LMS diameter reduction (%DS). The parameters that were analysed during ICUS study included maximum plaque burden (%) (Pbmax), minimal lumen area (LAmin) and lumen stenosis (%LS) calculated according to the formula: (LAmin/LAref) x 100%. Additionally, correlations between the corresponding parameters measured using QCA and ICUS were investigated. RESULTS: Both diagnostic techniques showed the most advanced degree of atherosclerosis in G3. All the G3 patients and 5 G2 patients had MLD values less than or equal to 2 mm. In G1 LAmin values exceeded 9 mm(2) in all patients, whereas among G2 patients 12 (15.5%) had LAmin lower than 6 mm(2), 29 pts. (37.66%) within the range of 6-9 mm(2) and in the remaining 36 pts. (46.75%) it exceeded 9 mm(2). In G3 LAmin values in 17 pts. (80.95%) did not exceed 6 mm(2) and in the remaining 4 pts. (19.05%) were slightly higher. Lumen reduction higher than 50% was noted in all G3 patients and 3 G2 patients (in all these 3 G2 patients LAmin values were lower than 6 mm(2)). All G3 pts. and 3 G2 pts. with LAmin value <6 mm(2) and %LS >50% had angina and a positive stress ECG test. All of these patients (n=24) underwent LMS stent implantation. CONCLUSIONS: 1. Minimal lumen diameter of LMS < or = 2 mm in quantitative angiography indicates a very high probability of significant stenosis of this vessel. 2. Ultrasound data analysis shows that besides LMS lumen area (<9 mm(2)) stenosis significance is determined by lumen reduction of more than 50%.  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