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   127048篇
  免费   7153篇
  国内免费   1103篇
耳鼻咽喉   1951篇
儿科学   1923篇
妇产科学   1873篇
基础医学   20238篇
口腔科学   3076篇
临床医学   11788篇
内科学   22706篇
皮肤病学   3967篇
神经病学   10304篇
特种医学   7302篇
外科学   16623篇
综合类   548篇
现状与发展   3篇
一般理论   27篇
预防医学   6691篇
眼科学   3190篇
药学   11401篇
中国医学   1455篇
肿瘤学   10238篇
  2023年   904篇
  2022年   2714篇
  2021年   4394篇
  2020年   2104篇
  2019年   2943篇
  2018年   3675篇
  2017年   2988篇
  2016年   3900篇
  2015年   5435篇
  2014年   6436篇
  2013年   7503篇
  2012年   11245篇
  2011年   10773篇
  2010年   6167篇
  2009年   5294篇
  2008年   7528篇
  2007年   7158篇
  2006年   6468篇
  2005年   5990篇
  2004年   5213篇
  2003年   4536篇
  2002年   3903篇
  2001年   3035篇
  2000年   2786篇
  1999年   2136篇
  1998年   913篇
  1997年   672篇
  1996年   515篇
  1995年   455篇
  1994年   392篇
  1993年   340篇
  1992年   750篇
  1991年   695篇
  1990年   638篇
  1989年   560篇
  1988年   467篇
  1987年   469篇
  1986年   333篇
  1985年   374篇
  1984年   264篇
  1983年   195篇
  1982年   134篇
  1981年   171篇
  1980年   132篇
  1979年   225篇
  1978年   165篇
  1977年   120篇
  1976年   133篇
  1975年   122篇
  1974年   139篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.

Objective

The advantage of arteriovenous fistulas (AVFs) in older patients requiring dialysis is controversial. We reviewed our vascular access experience in patients ≥70 years of age (older group) compared with younger patients.

Methods

We analyzed consecutive patients who underwent access surgery between 2013 and 2016. Primary success (PS) and primary patency (PP) data were analyzed between the older and younger groups before and after propensity score matching of the patients' characteristics and access composition. PS was defined as the achievement of access function that was amenable to two sessions of successful cannulation without early occlusion or maturation failure requiring revision. PP was defined as the time with uninterrupted patency without intervention.

Results

A total of 594 consecutive accesses were created among 563 patients, of whom 119 were allocated into each group after propensity score matching. In the whole cohort, 193 accesses (32.5%) were performed in older patients. AVFs were performed in 130 (67.4%) older patients and 293 (73.1%) younger patients. Regarding AVFs, the PS rate (83.6% in the older group vs 94.3% in the younger group; P = .001) and the overall PP at 6 and 12 months (73.1% and 57.1%, respectively, in the older group vs 86.7% and 77.7%, respectively, in the younger group; P = .009) were lower in the older group than in the younger group. However, no differences were found in the PS and PP rates for arteriovenous grafts between groups. Regarding the AVF location, the PS rate for forearm AVFs was significantly lower in the older group than in the younger group (76% vs 93%; P < .001); however, the PS rate of the upper arm was not different between the groups (94% vs 97%; P = .425). In the patients with PS, the PP rate of AVFs was similar between the two groups. In the older group with forearm AVFs, the median diameter of the radial artery was larger in the patients with PS than in the patients without PS (2.20 mm with PS vs 2.00 mm without PS; P = .008). The propensity score matching results demonstrated similar trends for the whole cohort, with lower PS (P = .042) and PP rates (P = .023) for AVF in the older group.

Conclusions

The outcomes after AVF were poorer in the older group than in the younger group, which was primarily due to unsatisfactory outcomes in patients with forearm AVFs. Thus, stricter criteria, especially regarding the radial artery diameter, should be applied for forearm AVFs in older patients, and additional research is necessary to delineate the risk factors for primary failure.  相似文献   
14.
BackgroundThe purpose of this study was to investigate and compare the clinical outcomes of dorsal suspension with those of neurectomy for the treatment of Morton’s neuroma.MethodsWe conducted a retrospective study of dorsal suspension and neurectomy group. The dorsal suspension was performed by dorsal transposition of neuroma over the dorsal transverse ligament after neurolysis. The visual analog scale (VAS), the Foot and Ankle Ability Measure (FAAM), postoperative satisfaction, and complications were evaluated.ResultsBoth groups reported significant pain relief, and there were no significant differences between the groups with respect to postoperative pain. The postoperative FAAM outcomes showed no significant between-group differences. Satisfaction analysis showed ‘excellent’ and ‘good’ results in the dorsal suspension and neurectomy groups (95% and 77.7%, respectively). Complications of numbness and paresthesia reported in the dorsal suspension group (5% and 5%, respectively) were significantly fewer than those of neurectomy group (61.1% and 33.3%, respectively) (both, p < .05).ConclusionsWith its favorable results, dorsal suspension can be another operative option for the treatment of Morton’s neuroma.Level of Evidence: Level III, retrospective comparative case series.  相似文献   
15.
16.
17.
18.
Fluid is usually restricted during thoracic surgery, and vasoactive agents are often administered to maintain blood pressure. One-lung ventilation (OLV) decreases arterial oxygenation; thus oxygen delivery to the brain can be decreased. In this study, we compared phenylephrine and dopamine with respect to maintaining cerebral oxygenation during OLV in major thoracic surgery.Sixty-three patients undergoing lobectomies were randomly assigned to the dopamine (D) or phenylephrine (P) group. The patients’ mean arterial pressure was maintained within 20% of baseline by a continuous infusion of dopamine or phenylephrine. Maintenance fluid was kept at 5 mL/kg/h. The depth of anesthesia was maintained with desflurane 1MAC and remifentanil infusion under bispectral index guidance. Regional cerebral oxygen saturation (rScO2) and hemodynamic variables were recorded using near-infrared spectroscopy and esophageal cardiac Doppler.The rScO2 was higher in the D group than the P group during OLV (OLV 60 min: 71 ± 6% vs 63 ± 12%; P = 0.03). The number of patients whose rScO2 dropped more than 20% from baseline was 0 and 6 in the D and P groups, respectively (P = 0.02). The D group showed higher cardiac output, but lower mean arterial pressure than the P group (4.7 ± 1.0 vs 3.9 ± 1.2 L/min; 76.7 ± 8.1 vs 84.5 ± 7.5 mm Hg; P = 0.02, P = 0.02). Among the variables, age, hemoglobin concentration, and cardiac output were associated with rScO2 by correlation analysis.Dopamine was superior to phenylephrine in maintaining cerebral oxygenation during OLV in thoracic surgery.  相似文献   
19.
The growth of online support groups has led to an expression effects paradigm within the health communication literature. Although religious support expression is characterized as a typical subdimension of emotional support, we argue that in the context of a life-threatening illness, the inclusion of a religious component creates a unique communication process. Using data from an online group for women with breast cancer, we test a theoretical expression effects model. Results demonstrate that for breast cancer patients, religious support expression has distinct effects from general emotional support messages, which highlights the need to further theorize expression effects along these lines.  相似文献   
20.
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