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   2336篇
  免费   92篇
  国内免费   12篇
耳鼻咽喉   95篇
儿科学   128篇
妇产科学   57篇
基础医学   218篇
口腔科学   63篇
临床医学   224篇
内科学   394篇
皮肤病学   31篇
神经病学   233篇
特种医学   80篇
外科学   589篇
综合类   28篇
预防医学   58篇
眼科学   64篇
药学   146篇
中国医学   3篇
肿瘤学   29篇
  2023年   9篇
  2022年   20篇
  2021年   32篇
  2020年   21篇
  2019年   37篇
  2018年   54篇
  2017年   39篇
  2016年   58篇
  2015年   62篇
  2014年   66篇
  2013年   113篇
  2012年   133篇
  2011年   155篇
  2010年   98篇
  2009年   80篇
  2008年   165篇
  2007年   168篇
  2006年   160篇
  2005年   162篇
  2004年   170篇
  2003年   134篇
  2002年   129篇
  2001年   62篇
  2000年   43篇
  1999年   39篇
  1998年   21篇
  1997年   11篇
  1996年   16篇
  1995年   14篇
  1994年   10篇
  1993年   3篇
  1992年   14篇
  1991年   11篇
  1990年   19篇
  1989年   11篇
  1988年   9篇
  1987年   10篇
  1986年   11篇
  1985年   10篇
  1984年   8篇
  1983年   6篇
  1982年   4篇
  1981年   5篇
  1980年   5篇
  1979年   12篇
  1977年   3篇
  1976年   5篇
  1975年   4篇
  1972年   2篇
  1968年   2篇
排序方式: 共有2440条查询结果,搜索用时 15 毫秒
11.
GM1 gangliosidosis is an autosomal recessive glycosphingolipid storage disease caused by defects in the enzyme beta-galactosidase. Three clinical forms (infantile-, juvenile-, and adult-onset) of the disease are recognized. Patients with infantile GM1 gangliosidosis present at birth or shortly thereafter with somatic and bony changes, followed by severe neurological deterioration ultimately leading to death within the first 2 years of life. We present the brain CT, MRI and MR spectroscopy (MRS) findings in a 17-month-old Turkish girl with infantile GM1 gangliosidosis. Neuroimaging findings in patients with infantile GM1 gangliosidosis have been reported only in a few cases. In this study, MRS of the thalamus was performed to study the metabolic changes in GM1 gangliosidosis. We showed a a decreased NAA/Cr ration and an increased Cho/Cr ratio. To our knowledge, this is the first report of magnetic resonance spectroscopy findings in type-1 GM1 gangliosidosis.  相似文献   
12.
Context: A patient followed in the outpatient spinal cord injury support clinic at a VA Medical Center with a prior remote history of a gunshot wound to the back and multiple prior myelograms presented with a recurrent waxing and waning weakness of the left lower extremity and intermittent incontinence of bowel and bladder.Findings: During the evaluation, the patient experienced an immediate albeit temporary improvement in symptoms after a diagnostic lumbar puncture performed for CT myelogram. The symptoms of myelopathy reoccurred several weeks, but then the patient had a similar experience with rapid improvement in symptoms after an accidental fall down a flight of steps. Subsequently, the foot weakness and incontinence returned one week later. The patient ultimately developed permanent improvement in signs and symptoms after surgical intervention which included intradural lysis of adhesions, incision of the arachnoid membrane and resection of a cystic lesion.Clinical relevance: Patients who experience unexpected, albeit transient improvement in myelopathic symptoms who are known or suspected to have arachnoiditis should be evaluated for surgically remediable lesions. Remediation of these lesions can potentially improve long term outcome.  相似文献   
13.
14.
PURPOSE OF REVIEW: To discuss the relationship between endometriosis and infertility, the impact of endometriosis on assisted reproductive techniques and also the benefits of prolonged use of gonadotropin-releasing hormone analogue before IVF in women with endometriosis. RECENT FINDINGS: The available evidence suggests that endometriosis is strongly associated with infertility. Many studies indicate lower pregnancy and implantation rates even in assisted reproductive cycles in women with endometriosis. It is well known that medical suppression of endometriosis does not appear to be warranted for endometriosis-associated infertility. Prolonged pretreatment with gonadotropin-releasing hormone analogue before IVF has been reported to improve clinical pregnancy rates in infertile women with endometriosis. SUMMARY: Based on the recently published data, infertile women with endometriosis may benefit from long-term pretreatment of gonadotropin-releasing hormone analogue prior to IVF.  相似文献   
15.
The interrelationship between glucagon action on splanchnic glucose output and cyclic AMP production was studied in healthy volunteers after hepatic venous catheterization. Glucagon was infused according to four different protocols to achieve arterial levels ranging from 300 to 9000 ng/I. Infusion of glucagon which resulted in arterial levels of the hormone of 4000-9000 ng/1 was associated with a marked increase in net splanchnic cyclic AMP production and in the arterial levels of the cyclic nucleotide. The rise in cyclic AMP efflux from the splanchnic area was transient but an augmented splanchnic production was still evident after 30 min of glucagon infusion. Splanchnic glucose output rose 3-5 fold. Infusion of glucagon at lower rates, resulting in arterial levels of 300-900 ng/I, did not measureably stimulate the efflux of cyclic AMP from the splanchnic area. In spite of this, splanchnic glucose output rose 2-3 fold and the blood glucose level increased 20-50% during glucagon infusion at these lower rates.

It is concluded that (1) factors other than cyclic AMP are rate limiting in the stimulation of hepatic glucose production, and (2) although cyclic AMP is an established 'second messenger' of glucagon action, other factors may also be of importance in mediating the physiological response of this hormone.  相似文献   
16.
17.
This randomized, active-controlled study evaluated the extent and duration of analgesia after administration of liposome bupivacaine (LB), a novel formulation of bupivacaine, compared with bupivacaine HCl given via local infiltration in excisional hemorrhoidectomy. One hundred patients were randomly assigned to receive a single dose of bupivacaine HCl 75 mg (0.25% with 1:200,000 epinephrine) or LB 66, 199, or 266 mg upon completion of hemorrhoidectomy. Postoperative pain intensity was assessed using a numeric rating scale at rest to calculate a cumulative pain score (area under the curve). Cumulative pain scores were significantly lower with LB at each study dose (P < 0.05) compared with bupivacaine HCl 72 hours after surgery. Post hoc analysis showed that mean total postoperative opioid consumption was statistically significantly lower for the LB 266-mg group compared with the bupivacaine HCl group during the 12- to 72-hour postoperative period (P = 0.019). Median time to first opioid use was 19 hours for LB 266 mg versus 8 hours for bupivacaine HCl (P = 0.005). Incidence of opioid-related adverse events was 4 per cent for LB 266 mg compared with 35 per cent for bupivacaine HCl (P = 0.007). Local infiltration with LB resulted in significantly reduced postsurgical pain compared with bupivacaine HCl in patients after hemorrhoidectomy surgery.  相似文献   
18.
Risk factors for stroke following coronary artery bypass operations   总被引:1,自引:0,他引:1  
BACKGROUND: Although the overall complication rates have been decreased significantly in recent years, stroke rates still remain high in patients undergoing coronary bypass operations. This study is designed to evaluate the risk factors for stroke in patients who had undergone coronary artery bypass surgery in an 8-year period in our clinic. METHODS: Between 1995 and 2003, 8547 coronary artery operations under cardiopulmonary bypass were performed. Retrospective analysis of the patient files revealed that 75 (0.9%) patients had stroke in the early postoperative period. RESULTS: Mean age of these patients was 62.3 +/- 9.5 years, and 54 (72%) were males. Stroke rate was 1.2% between 1995 and 1998 and this was significantly higher from the stroke rate (0.7%) of the period 1998 to 2003 (p = 0.03). Major technical differences between these two periods were the routine application of preoperative carotid arteries Doppler evaluation and intraoperative epiaortic echocardiography after 1998. Higher age (p = 0.000), female sex (p = 0.005), smoking (p = 0.03), presence of diabetes mellitus (p = 0.01), hypertension (p = 0.008), and left main coronary artery disease (p = 0.001), carotid surgery (p = 0.000), and peripheral vascular disease (p = 0.049) were identified as important risk factors in univariate analysis for stroke development. Higher age (p = 0.000; OR = 21.38), left main coronary artery disease (p = 0.007; OR = 7.26), peripheral vascular disease (p = 0.050; OR = 3.08), and operation date before 1998 (p = 0.012; OR = 6.33) were identified as important risk factors in logistic regression analysis. According to intraoperative epiaortic ultrasonography, operative strategy was changed in 9% of patients. Thirty-seven (49.3%) of the stroke patients died. Female sex (p = 0.023; OR = 5.18) and preoperative hypertension (p = 0.045; OR = 4.03) were observed as significant risk factors for mortality after stroke. CONCLUSION: Development of stroke is one of the major reasons of mortality after coronary artery bypass operations. It is essential to take all the measures to prevent this complication, especially in patients with known risk factors. Evaluation of carotid arteries prior to operation and application of routine intraoperative epiaortic echocardiography may in part eliminate stroke.  相似文献   
19.
PURPOSE: The purpose of this study was to determine whether the continuous horizontal mattress suture technique can replace the continuous simple suture technique and to compare the results with other microvascular suture procedures. METHODS: Sixty-four femoral arteries of 32 Sprague-Dawley rats were used in this study. The animals were divided equally into 4 groups with 16 anastomoses in each group. The arteries (0.8-1.0 mm diameter) were anastomosed by using the continuous horizontal mattress suture technique in group I, interrupted horizontal mattress suture technique in group II, simple interrupted suture technique in group III, and simple continuous suture technique in group IV. At the end of the anastomosis time, leakage, and patency were assessed and graded in all groups. On the 14th day after surgery the rats were killed and 5 patent specimens from each group were examined under light microscopy for histology. One specimen from each group was prepared for scanning of the endothelial surface under electron scanning microscopy. RESULTS: Group I anastomoses were performed the most quickly. Groups I and III anastomoses had 100% patency rates. Under light microscopy the edge eversion was apparent consistently and under electron microscopy all endothelial surfaces were intact and no suture material was seen in groups I and II. In group III some suture material was covered by endothelial cells and lumen surfaces were torn; endothelization also was rough compared with groups I and II. In group IV suture material was seen in the lumen because of a loose suture knot. The endothelium also was not regular. CONCLUSIONS: The horizontal mattress suturing technique is the only technique in which the suture material never contacts the lumen. Continuous horizontal mattress suture technique is superior to the other microvascular procedures and is the safest and fastest procedure for microvascular anastomosis in rats.  相似文献   
20.
To investigate the effect of cyclosporine A (Cyc A) on the development of fibroadenomas, 30 renal transplant patients and 20 chronic renal failure patients on dialysis were breast examined with ultrasonography and/or mammography. Of the renal transplant patients, 17 were receiving Cyc A-based combination therapy for immunosuppression. All patients were female with the age range of 29.7+/-9.2 years in the transplant group and 33.95+/-9.91 in the dialysis group. Eight of the 17 patients receiving Cyc A had fibroadenomas, 5 of them having bilateral lesions. None of the other patients, those on dialysis and on non-Cyc A combination therapy had fibroadenomas. A significant difference for fibroadenoma incidence in patients receiving Cyc A combination immunosuppression was found.  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