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   2507篇
  免费   144篇
  国内免费   11篇
耳鼻咽喉   12篇
儿科学   35篇
妇产科学   27篇
基础医学   308篇
口腔科学   97篇
临床医学   166篇
内科学   617篇
皮肤病学   73篇
神经病学   336篇
特种医学   95篇
外科学   291篇
综合类   8篇
预防医学   85篇
眼科学   22篇
药学   167篇
中国医学   5篇
肿瘤学   318篇
  2023年   23篇
  2022年   45篇
  2021年   63篇
  2020年   32篇
  2019年   46篇
  2018年   69篇
  2017年   45篇
  2016年   64篇
  2015年   89篇
  2014年   116篇
  2013年   124篇
  2012年   165篇
  2011年   176篇
  2010年   104篇
  2009年   100篇
  2008年   150篇
  2007年   165篇
  2006年   164篇
  2005年   170篇
  2004年   168篇
  2003年   142篇
  2002年   133篇
  2001年   28篇
  2000年   17篇
  1999年   28篇
  1998年   25篇
  1997年   25篇
  1996年   19篇
  1995年   22篇
  1994年   12篇
  1993年   15篇
  1992年   8篇
  1991年   11篇
  1990年   10篇
  1989年   9篇
  1988年   4篇
  1987年   7篇
  1986年   7篇
  1985年   4篇
  1984年   12篇
  1983年   5篇
  1982年   9篇
  1981年   7篇
  1980年   3篇
  1979年   2篇
  1976年   2篇
  1975年   3篇
  1974年   3篇
  1972年   2篇
  1937年   1篇
排序方式: 共有2662条查询结果,搜索用时 15 毫秒
81.
In the United States, Spanish-speaking patients with diabetes often receive inadequate dietary counseling. Providing language and culture-concordant dietary counseling on an ongoing basis is critical to diabetes self-care. To determine if automated telephone nutrition support (ATNS) counseling could help patients improve glycemic control by duplicating a successful pilot in Mexico in a Spanish-speaking population in Oakland, California. A prospective randomized open-label trial with blinded endpoint assessment (PROBE) was performed. The participants were seventy-five adult patients with diabetes receiving care at a federally qualified health center in Oakland, California. ATNS, a computerized system that dialed patients on their phones, prompted them in Spanish to enter (via keypad) portions consumed in the prior 24 hours of various cultural-specific dietary items, and then provided dietary feedback based on proportion of high versus low glycemic index foods consumed. The control group received the same ATNS phone calls 14 weeks after enrollment. The primary outcome was hemoglobin A1c % (A1c) 12 weeks following enrollment. Participants had no significant improvement in A1c (–0.3% in the control arm, –0.1% in the intervention arm, P = .41 for any difference) or any secondary parameters. In our study, an ATNS system did not improve diabetes control in a Spanish-speaking population in Oakland.  相似文献   
82.
83.
Retrospective population-based studies showed that in cancer patients venous thromboembolism (VTE) is associated with reduced survival. Master Oncology is a multicenter study in patients with solid advanced cancer aimed at assessing (1) risk factors for VTE using a case–control design, and (2) survival in cases (patients with VTE) and controls (patients without VTE). Survival data were prospectively collected for at least 10 months. Overall, 237 cases and 339 controls were included in the analysis. The following factors were found to be associated with an increased risk of VTE: body mass index (BMI; OR 2.02; 95 % CI 1.31–3.12 for ≥26 vs. <23 kg/m2), ECOG score (OR 2.14; 95 % CI 1.47–3.11 for grade 1, and 3.32; 95 % CI 1.64–6.00 for grade 2–3, compared to grade 0) and recent diagnosis of cancer (OR 1.90; 95 % CI 1.33–2.71 for <12 vs. ≥12 months). After an average prospective observation of 8.3 months, 136 cases (57.4 %) and 127 controls (37.5 %) died with a median survival of 8.7 (95 % CI 7.5–10.9) and 14.3 months (95 % CI 12.2–18.7), respectively, (Wilcoxon = 27.72, p < 0.001; multivariate hazard ratio 1.55; 95 % CI 1.21–2.00). Median survival time was reduced for both patients with symptomatic (Wilcoxon = 35.22, p < 0.001) and asymptomatic VTE (Wilcoxon = 4.63, p = 0.031). Patients with advanced solid cancer, high BMI, high ECOG score, and recent diagnosis of cancer are associated with an increased risk for VTE. Patients with both symptomatic and asymptomatic VTE have a reduced survival compared to those without VTE.  相似文献   
84.
Cardiotrophin-1 (CT-1) is a member of the interleukin (IL-6) family of cytokines. Plasma CT-1 levels correlate with the left ventricle mass index in patients with dilatated cardiomyopathy and congestive heart failure (CHF). The aim of this paper was to evaluate CT-1 plasma levels, before and after cardiac resynchronization therapy CRT, and to characterizeits prognostic role in patients with CHF. Fifty-two consecutive patients (M/F = 39/13; 56 ± 11 years old) underwent clinical and echocardiographic evaluation, and blood sample collection at baseline. The same evaluation was repeated 6.4 ± 0.79 months after CRT. Patients with a decreased LV end-systolic volume by at least 15% (reverse remodeling) were considered echo responders to CRT. Twenty-nine patients (56%) were responders to CRT. After CRT, only 15 patients (29%) showed increased CT-1 after CRT. They were all non responders to CRT. A multivariate, logistic modelshowed CT-1 as an independent predictor of CRT echo response (p = 0.005; OR 0.97). During follow-up (18 ± 7 months), 21 cardiac events in 18 patients occurred. A Cox multivariable model showed plasma BNP pre-CRT (p = 0.02; CI 1.2–5.6; OR 3.1) and CT1 post-CRT (p = 0.01; CI 1.4–4.3; OR 2.7) as independent predictors of cardiac events. Analysis of CT-1 plasma levels deserves future consideration for larger, longitudinal studies in patients with CHF.  相似文献   
85.
86.
Since the pioneering works of Carr-Purcell and Meiboom-Gill [Carr HY, Purcell EM (1954) Phys Rev 94:630; Meiboom S, Gill D (1985) Rev Sci Instrum 29:688], trains of π-pulses have featured amongst the main tools of quantum control. Echo trains find widespread use in nuclear magnetic resonance spectroscopy (NMR) and imaging (MRI), thanks to their ability to free the evolution of a spin-1/2 from several sources of decoherence. Spin echoes have also been researched in dynamic decoupling scenarios, for prolonging the lifetimes of quantum states or coherences. Inspired by this search we introduce a family of spin-echo sequences, which can still detect site-specific interactions like the chemical shift. This is achieved thanks to the presence of weak environmental fluctuations of common occurrence in high-field NMR--such as homonuclear spin-spin couplings or chemical/biochemical exchanges. Both intuitive and rigorous derivations of the resulting "selective dynamical recoupling" sequences are provided. Applications of these novel experiments are given for a variety of NMR scenarios including determinations of shift effects under inhomogeneities overwhelming individual chemical identities, and model-free characterizations of chemically exchanging partners.  相似文献   
87.
88.
89.

Objectives

Implant rehabilitation in oral lichen planus (OLP) is a major challenge for clinicians and patients. There is limited scientific evidence, primarily case reports and small case series. We conducted a literature review of data on the effectiveness and safety of implant rehabilitation in OLP patients.

Material and methods

We searched MEDLINE, Embase and Cochrane databases for articles on implant placement in OLP patients (searches from 1980 to 2011).

Results

Eight studies (41 OLP patients rehabilitated with 135 implants) met the inclusion criteria. Survival rate of implants was 94.8% over a mean follow-up of 56.5?months.

Conclusions

There is very limited evidence on the safety and benefits of implant placement in OLP patients. Implant loss appears not to be directly related to OLP, but linked to factors such as parafunctions, poor bone quality and marginal mandibular resection. The benefits and harms of using implants in people with OLP require thorough evaluation in properly designed randomised, controlled studies.

Clinical relevance

OLP is not an absolute contraindication for implant insertion and there is no increased risk of failure. Implants should be positioned only if mucosal signs and symptoms are in the remission phase. A careful oral hygiene and frequent follow-up are the main recommendations in OLP patients rehabilitated with implants.  相似文献   
90.
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