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   196117篇
  免费   2244篇
  国内免费   42篇
耳鼻咽喉   1269篇
儿科学   7294篇
妇产科学   3716篇
基础医学   19111篇
口腔科学   1829篇
临床医学   15829篇
内科学   34177篇
皮肤病学   854篇
神经病学   18552篇
特种医学   9266篇
外科学   30609篇
综合类   2565篇
一般理论   32篇
预防医学   21222篇
眼科学   3043篇
药学   10656篇
中国医学   646篇
肿瘤学   17733篇
  2023年   152篇
  2022年   229篇
  2021年   419篇
  2020年   291篇
  2019年   452篇
  2018年   22361篇
  2017年   17701篇
  2016年   19892篇
  2015年   1420篇
  2014年   1510篇
  2013年   1837篇
  2012年   8500篇
  2011年   22640篇
  2010年   19618篇
  2009年   12277篇
  2008年   20903篇
  2007年   23217篇
  2006年   2009篇
  2005年   3625篇
  2004年   4828篇
  2003年   5652篇
  2002年   3805篇
  2001年   475篇
  2000年   540篇
  1999年   331篇
  1998年   451篇
  1997年   419篇
  1996年   243篇
  1995年   272篇
  1994年   248篇
  1993年   173篇
  1992年   137篇
  1991年   163篇
  1990年   181篇
  1989年   137篇
  1988年   107篇
  1987年   92篇
  1986年   58篇
  1985年   90篇
  1984年   74篇
  1983年   69篇
  1982年   84篇
  1981年   56篇
  1980年   73篇
  1974年   29篇
  1969年   28篇
  1938年   61篇
  1934年   32篇
  1932年   56篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.

Background  

Total hip arthroplasty is a successful surgery, that fails at a rate of approximately 10% at ten years from surgery. Causes for failure are mainly aseptic loosening of one or both components partially due to wear of articular surfaces and partially to design. The present analysis aimed to identify risk factors and quantify their effects on aseptic failure.  相似文献   
82.

Background  

Skin and soft tissue infections are increasingly prevalent clinical problems, and it is important for health care practitioners to be well trained in how to treat skin abscesses. A realistic model of abscess incision and drainage will allow trainees to learn and practice this basic physician procedure.  相似文献   
83.
The objective of this study is to compare the effects of three different anesthetic combinations on the electroretinogram in the same animals under similar laboratory conditions. Thiopental–isoflurane (TI), medetomidine–ketamine (MK), and xylazine–ketamine (XK) were used on each of 12 healthy miniature schnauzer dogs (MS) with a period of at least 3 weeks in between subsequent anesthesia protocols, using the Dog Standard Protocol. The scotopic ERGs consisted of scotopic low stimulus strength (S) responses designated S1, S2, S3, S4, and S5, at 1, 5, 10, 15, and 20 min after dark adaptation, respectively, and scotopic standard stimulus strength (S-ST) responses. The photopic ERGs consisted of a photopic single flash (P) response and 31 Hz flicker (P-FL) responses. For S-ST (2.5 cd s/m2), the amplitude of the a-wave using TI was significantly lower than that using MK (adjusted P = 0.05) and XK (adjusted P = 0.03), and the implicit time of the a-wave was significantly shorter than that using MK (adjusted P = 0.04). For P (2.5 cd s/m2), the amplitude of the b-wave using XK was significantly higher than that using MK (adjusted P = 0.01). The implicit times of the b-wave using TI was significantly longer and shorter than that of MK for S1, S2 and P-FL and for S4 and S-ST, respectively, and than that of XK for S2 and P-FL and for S5 and S-ST, respectively. The results of the present study showed that TI affected both the amplitude and the implicit time of the a-wave for S-ST and the implicit time of the b-wave relatively more so than was the case when using XK or MK. Therefore, it appears that either XK or MK could be advantageous to use rather than TI for clinical studies.  相似文献   
84.
Conclusion  We would like to stress that we do not necessarily consider AC for SPECT MPI to be unfeasible or unworthy of scientific pursuit; indeed, a great deal of creative scientific effort has been poured into this area of investigation over the past 3 decades, and much of it has contributed to a better understanding of the physics, as well as the clinical aspects, of our field. However, the great variety of available AC hardware and software “flavors,” the historical pattern of commercial release of insufficiently validated AC implementations, and the increasingly clouded health care reimbursement horizon may have created an environment where the envisioned users of the technology have been desensitized and discouraged from expecting it to ever come to fruition in a standardized, validated, and costeffective form. It has been reported as recently as 2005 that the “entire base of SPECT cameras has only 5% of systems with attenuation correction.”8 Perhaps the reports of AC’s demise are exaggerated, but it certainly seems as if the people have spoken and, after readying themselves for the wolf one too many times, have come to the conclusion that “the future (of AC) ain’t what it used to be” . . .at least not yet.  相似文献   
85.
BACKGROUND: In Marfan's syndrome, there is a paucity of data regarding intervention criteria for surgery of the dissected thoraco-abdominal aorta. METHODS: A retrospective analysis of 22 Marfan's patients with distal aortic dissection managed between September 1999 and April 2006 was performed. Serial diameters and linear expansion rates were calculated from imaging studies and the outcome of intervention was analysed. RESULTS: There were 14/22 male patients (median age 38 years), and 18 had prior aortic surgery. Surgery was recommended in 20 patients and undertaken in 19 (1 died prior to operation). Of the operated patients, 2 presented with rupture, 2 with airway obstruction, 1 with intermittent paraplegia and 14 underwent planned surgery for increased expansion rate or pain. All patients had residual type A or chronic type B dissection. The median aortic dimension at surgery was 6.7 cm (interquartile range (IQR) 5.5-8.2). The preoperative mean expansion rate increased from 0.5 cm/year to 1.7 cm/year (p<0.001), prior to operation. Fifteen patients underwent Crawford Extent II, two underwent Extent I and two underwent Extent III repair. Profound hypothermia and CSF drainage was used in 16 and 18 patients, respectively. There was no early mortality, paraplegia or renal failure. At a median postoperative follow-up of 56 months (range 6-86), the survival of the operated cohort was 90%. CONCLUSIONS: Thoraco-abdominal aortic aneurysm repair in Marfan's syndrome can be performed with good outcomes. Intervention should be based on size or accelerated expansion. Any role of endovascular management needs careful consideration.  相似文献   
86.
Survival after resection of colorectal liver metastases has traditionally been associated with clinicopathologic factors. We sought to investigate whether echogenicity of colorectal liver metastasis as assessed by intraoperative ultrasound (IOUS) was a prognostic factor after hepatic resection. Prospective data on tumor IOUS appearance were collected in 84 patients who underwent hepatic resection for colorectal liver metastasis. Images were digitally recorded, blindly reviewed, and scored for echogenicity (hypo-, iso-, or hyperechoic). The median tumor number was 1 and the median tumor size was 5.0 cm. At the time of surgery, the IOUS appearance of the colorectal liver metastases were hypoechoic in 35 (41.7%) patients, isoechoic in 37 (44.0%) patients, and hyperechoic in 12 (14.3%) patients. Traditional clinicopathologic prognostic factors were similarly distributed among the three echogenicity groups (all p > 0.05). Patients with a hypoechoic lesion had a significantly shorter median survival (30.2 months) compared with patients who had either an isoechoic (53.2 months) or hyperechoic (42.3 months) lesion (p = 0.005). The 5-year survival after hepatic resection of colorectal liver metastasis was also associated with the echogenic appearance of the lesion (hypoechoic 14.4 vs isoechoic 37.4 vs hyperechoic 46.2%) (p < 0.05). Intraoperative ultrasound echogenicity should be considered a prognostic factor after hepatic resection of metastatic colorectal cancer. This study was presented at the 47th annual meeting of The Society for Surgery of the Alimentary Tract, Los Angeles, CA, USA, 22 May 2006.  相似文献   
87.
Gastroesophageal reflux disease (GERD) is a common disease and can be successfully treated by laparoscopic fundoplication. This article describes the technique of laparoscopic surgery for GERD with a focus on operative pitfalls.  相似文献   
88.
Management of upper gastrointestinal bleeding because of erosion of vessels by esophageal cancer may be challenging. We present herein the angiographic images of a 49-year-old patient who was admitted with massive bleeding from a tumor-eroded inferior thyroid artery. Attempts to control the bleeding by means of flexible endoscopy and insertion of a Sengstaken–Blakemore tube had failed. The diagnosis was impressively demonstrated by multislice computed tomography with intravenous contrast in the arterial phase and multiplanar reconstructions (computed tomography angiography) and by digital subtraction angiography. The bleeding was successfully treated with superselective catheterization and coiling of the eroded vessel.  相似文献   
89.
90.
Abstract Background: Primary shoulder hemiarthroplasty is an established treatment modality for complex fractures of the proximal humerus. Long-term functional outcome is often disappointing. However, little is known about social implications particularly in the elderly. Methods: A single-institution case series of consecutive geriatric patients (age > 70 years) treated with shoulder hemiarthroplasty for complex fractures of the proximal humerus between 1994 and 1997 was analysed. Postoperative morbidity, long-term function, radiological outcome and social implications were evaluated. Results: Seventy-seven patients fulfilled the study criteria. Median age at the time of operation was 80 years (range 70–93 years). Systemic and local postoperative complications were observed in 8% including 2 patients (3%) with revision surgery. Postoperative mortality was 1%. Forty-eight patients (62%) were available for follow-up (median 49 months, range 25–80 months), 22 (29%) died from causes unrelated to hemiarthroplasty before follow-up and 7 patients (9%) did not attend follow-up examination. Median Constant-Murley score was 41 points (range 17–77 points). Long-term results concerning pain were satisfying. The Oxford shoulder score ranged from 14 to 40 (median 30). Forty-one patients (85%) still lived in their original environment and managed their daily life independently despite poor shoulder function. Four patients (8%) lived in a retirement home and 3 (6%) in a nursery home. Eighty percent of our patients were still able to use public transportation, do the daily shopping and wash their whole body by themselves. Conclusion: Most patients managed their daily life independently despite poor shoulder function.  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