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   29879篇
  免费   2857篇
  国内免费   48篇
耳鼻咽喉   310篇
儿科学   1135篇
妇产科学   618篇
基础医学   3843篇
口腔科学   538篇
临床医学   3688篇
内科学   5111篇
皮肤病学   507篇
神经病学   2915篇
特种医学   884篇
外国民族医学   1篇
外科学   4233篇
综合类   728篇
一般理论   24篇
预防医学   3600篇
眼科学   455篇
药学   2307篇
  1篇
中国医学   45篇
肿瘤学   1841篇
  2023年   215篇
  2022年   291篇
  2021年   816篇
  2020年   448篇
  2019年   770篇
  2018年   919篇
  2017年   646篇
  2016年   625篇
  2015年   701篇
  2014年   987篇
  2013年   1408篇
  2012年   1974篇
  2011年   2057篇
  2010年   1106篇
  2009年   978篇
  2008年   1599篇
  2007年   1605篇
  2006年   1555篇
  2005年   1523篇
  2004年   1381篇
  2003年   1302篇
  2002年   1240篇
  2001年   719篇
  2000年   624篇
  1999年   541篇
  1998年   259篇
  1997年   210篇
  1996年   252篇
  1995年   201篇
  1994年   193篇
  1993年   172篇
  1992年   393篇
  1991年   393篇
  1990年   429篇
  1989年   381篇
  1988年   303篇
  1987年   330篇
  1986年   273篇
  1985年   293篇
  1984年   236篇
  1983年   187篇
  1982年   149篇
  1981年   134篇
  1980年   129篇
  1979年   207篇
  1978年   162篇
  1977年   133篇
  1976年   112篇
  1974年   138篇
  1973年   115篇
排序方式: 共有10000条查询结果,搜索用时 744 毫秒
11.
12.

Background

Partial nephrectomy (PN) is generally favored for cT1 tumors over radical nephrectomy (RN) when technically feasible. However, it can be unclear whether the additional risks of PN are worth the magnitude of renal function benefit.

Objective

To develop preoperative tools to predict long-term estimated glomerular filtration rate (eGFR) beyond 30 d following PN and RN, separately.

Design, setting, and participants

In this retrospective cohort study, patients who underwent RN or PN for a single nonmetastatic renal tumor between 1997 and 2014 at our institution were identified. Exclusion criteria were venous tumor thrombus and preoperative eGFR <15 ml/min/1.73 m2.

Intervention

RN and PN.

Outcome measurements and statistical analysis

Hierarchical generalized linear mixed-effect models with backward selection of candidate preoperative features were used to predict long-term eGFR following RN and PN, separately. Predictive ability was summarized using marginal RGLMM2, which ranges from 0 to 1, with higher values indicating increased predictive ability.

Results and limitations

The analysis included 1152 patients (13 206 eGFR observations) who underwent RN and 1920 patients (18 652 eGFR observations) who underwent PN, with mean preoperative eGFRs of 66 ml/min/1.73 m2 (standard deviation [SD] = 18) and 72 ml/min/1.73 m2 (SD = 20), respectively. The model to predict eGFR after RN included age, diabetes, preoperative eGFR, preoperative proteinuria, tumor size, time from surgery, and an interaction between time from surgery and age (marginal RGLMM2=0.41). The model to predict eGFR after PN included age, presence of a solitary kidney, diabetes, hypertension, preoperative eGFR, preoperative proteinuria, surgical approach, time from surgery, and interaction terms between time from surgery and age, diabetes, preoperative eGFR, and preoperative proteinuria (marginal RGLMM2). Limitations include the lack of data on renal tumor complexity and the single-center design; generalizability needs to be confirmed in external cohorts.

Conclusions

We developed preoperative tools to predict renal function outcomes following RN and PN. Pending validation, these tools should be helpful for patient counseling and clinical decision-making.

Patient summary

We developed models to predict kidney function outcomes after partial and radical nephrectomy based on preoperative features. This should help clinicians during patient counseling and decision-making in the management of kidney tumors.  相似文献   
13.
14.
15.
Motion is a major confound in diffusion‐weighted imaging (DWI) in the body, and it is a common cause of image artefacts. The effects are particularly severe in cardiac applications, due to the nonrigid cyclical deformation of the myocardium. Spin echo‐based DWI commonly employs gradient moment‐nulling techniques to desensitise the acquisition to velocity and acceleration, ie, nulling gradient moments up to the 2nd order (M2‐nulled). However, current M2‐nulled DWI scans are limited to encode diffusion along a single direction at a time. We propose a method for designing b‐tensors of arbitrary shapes, including planar, spherical, prolate and oblate tensors, while nulling gradient moments up to the 2nd order and beyond. The design strategy comprises initialising the diffusion encoding gradients in two encoding blocks about the refocusing pulse, followed by appropriate scaling and rotation, which further enables nulling undesired effects of concomitant gradients. Proof‐of‐concept assessment of in vivo mean diffusivity (MD) was performed using linear and spherical tensor encoding (LTE and STE, respectively) in the hearts of five healthy volunteers. The results of the M2‐nulled STE showed that (a) the sequence was robust to cardiac motion, and (b) MD was higher than that acquired using standard M2‐nulled LTE, where diffusion‐weighting was applied in three orthogonal directions, which may be attributed to the presence of restricted diffusion and microscopic diffusion anisotropy. Provided adequate signal‐to‐noise ratio, STE could significantly shorten estimation of MD compared with the conventional LTE approach. Importantly, our theoretical analysis and the proposed gradient waveform design may be useful in microstructure imaging beyond diffusion tensor imaging where the effects of motion must be suppressed.  相似文献   
16.
17.
Background: While over half of stroke survivors recover the ability to walk without assistance, deficits persist in the performance of walking adaptations necessary for safe home and community mobility. One such adaptation is the ability to walk or step backward. Post-stroke rehabilitation rarely includes backward walking (BW) assessment and BW deficits have not been quantified in post-stroke community ambulators.

Objective: To quantify spatiotemporal and kinematic BW characteristics in post-stroke community ambulators and compare their performance to controls.

Methods: Individuals post-stroke (n = 15, 60.1 ± 12.9 years, forward speed: 1.13 ± 0.23 m/s) and healthy adults (n = 12, 61.2 ± 16.2 years, forward speed: 1.40 ± 0.13 m/s) performed forward walking (FW) and BW during a single session. Step characteristics and peak lower extremity joint angles were extracted using 3D motion analysis and analyzed with mixed-method ANOVAs (group, walking condition).

Results: The stroke group demonstrated greater reductions in speed, step length and cadence and a greater increase in double-support time during BW compared to FW (p < .01). Compared to FW, the post-stroke group demonstrated greater reductions in hip extension and knee flexion during BW (p < .05). The control group demonstrated decreased plantarflexion and increased dorsiflexion during BW, but these increases were attenuated in the post-stroke group (p < .05).

Conclusions: Assessment of BW can unmask post-stroke walking impairments not detected during typical FW. BW impairments may contribute to the mobility difficulties reported by adults post-stroke. Therefore, BW should be assessed when determining readiness for home and community ambulation.  相似文献   

18.
Diabetes news     
Martin J. Kurian, Peter J. Rentzepis, Ann M. Carracher, and Kelly L. Close are of Close Concerns ( http://www.closeconcerns.com ), a healthcare information company focused exclusively on diabetes and obesity care. Close Concerns publishes Closer Look, a periodical that brings together news and insights in these areas. Each month, the Journal of Diabetes includes this News feature, in which Kurian, Rentzepis, Carracher, and Close review the latest developments relevant to researchers and clinicians.  相似文献   
19.
Purpose: To test the effectiveness of a school-based, nurse-facilitated support group in increasing perceptions of scholastic competence, social acceptance, behavioral conduct, perceived athletic competence, perceived physical appearance, and perceived global self-worth in preadolescents diagnosed with attention deficit disorder (ADD) or attention deficit hyperactivity disorder (ADHD).
Design: A quasi-experimental design with 65 preadolescents diagnosed with ADD or ADHD in an upper-middle class community in the United States.
Methods: Participants randomly assigned to either the control or experimental group completed Harter's Self-Perception Profile for Children instrument at the beginning of the study and 4 weeks later. Students in the experimental condition participated in a school-nurse facilitated support group which met twice weekly for 4 weeks.
Findings: Participants in the support group had increased scores on each of the six subscales, with significant increases on four of the subscales, including perceived social acceptance, perceived athletic competence, perceived physical appearance, and perceived global self-worth.
Conclusion: Participation in a school-based, nurse-led support group was positively associated with perception of self-worth in preadolescents diagnosed with ADD or ADHD.  相似文献   
20.
Pancreatic panniculitis is an uncommon condition that can occur in association with pancreatic disease. We present a case of pancreatic panniculitis in a female pancreas-kidney transplant recipient 5 months post-transplant. The patient was on standard immunosuppressive medications and had acute rejection of her renal allograft. The diagnosis of allograft pancreatitis and rejection presenting with pancreatic panniculitis was supported clinically, histopathologically and by laboratory and imaging data. This is the fourth case of pancreatic panniculitis occurring in a transplant recipient and the first in a simultaneous pancreas-kidney transplant recipient. It is also the first case associated with allograft rejection. Clinicians should be aware that pancreatic panniculitis may be a manifestation of underlying allograft pancreatic disease.  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