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   4656篇
  免费   411篇
  国内免费   29篇
耳鼻咽喉   13篇
儿科学   199篇
妇产科学   59篇
基础医学   536篇
口腔科学   75篇
临床医学   521篇
内科学   910篇
皮肤病学   55篇
神经病学   334篇
特种医学   242篇
外科学   611篇
综合类   161篇
一般理论   3篇
预防医学   466篇
眼科学   133篇
药学   313篇
中国医学   11篇
肿瘤学   454篇
  2023年   25篇
  2022年   52篇
  2021年   107篇
  2020年   57篇
  2019年   115篇
  2018年   92篇
  2017年   67篇
  2016年   96篇
  2015年   103篇
  2014年   138篇
  2013年   217篇
  2012年   261篇
  2011年   249篇
  2010年   160篇
  2009年   133篇
  2008年   219篇
  2007年   230篇
  2006年   247篇
  2005年   230篇
  2004年   226篇
  2003年   222篇
  2002年   170篇
  2001年   185篇
  2000年   144篇
  1999年   117篇
  1998年   62篇
  1997年   42篇
  1996年   55篇
  1995年   47篇
  1994年   36篇
  1993年   42篇
  1992年   64篇
  1991年   69篇
  1990年   49篇
  1989年   58篇
  1988年   45篇
  1987年   61篇
  1986年   34篇
  1985年   45篇
  1984年   30篇
  1983年   32篇
  1982年   24篇
  1980年   24篇
  1978年   27篇
  1977年   34篇
  1976年   24篇
  1975年   29篇
  1974年   28篇
  1972年   32篇
  1970年   24篇
排序方式: 共有5096条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
OBJECTIVE: To assess the therapeutic value of Gastrografin in the management of adhesive small bowel obstruction after unsuccessful conservative treatment. SUMMARY BACKGROUND DATA: Gastrografin is a hyperosmolar water-soluble contrast medium. Besides its predictive value for the need for surgery, there is probably a therapeutic role of this contrast medium in adhesive small bowel obstruction. METHODS: Patients with clinical evidence of adhesive small bowel obstruction were given trial conservative treatment unless there was suspicion of strangulation. Those who responded in the initial 48 hours had conservative treatment continued. Patients showing no clinical and radiologic improvement in the initial 48 hours were randomized to undergo either Gastrografin meal and follow-through study or surgery. Contrast that appeared in the large bowel within 24 hours was regarded as a partial obstruction, and conservative treatment was continued. Patients in whom contrast failed to reach the large bowel within 24 hours were considered to have complete obstruction, and laparotomy was performed. For patients who had conservative treatment for more than 48 hours with or without Gastrografin, surgery was performed when there was no continuing improvement. RESULTS: One hundred twenty-four patients with a total of 139 episodes of adhesive obstruction were included. Three patients underwent surgery soon after admission for suspected bowel strangulation. Strangulating obstruction was confirmed in two patients. One hundred one obstructive episodes showed improvement in the initial 48 hours and conservative treatment was continued. Only one patient required surgical treatment subsequently after conservative treatment for 6 days. Thirty-five patients showed no improvement within 48 hours. Nineteen patients were randomized to undergo Gastrografin meal and follow-through study and 16 patients to surgery. Gastrografin study revealed partial obstruction in 14 patients. Obstruction resolved subsequently in all of them after a mean of 41 hours. The other five patients underwent laparotomy because the contrast study showed complete obstruction. The use of Gastrografin significantly reduced the need for surgery by 74%. There was no complication that could be attributed to the use of Gastrografin. No strangulation of bowel occurred in either group. CONCLUSIONS: The use of Gastrografin in adhesive small bowel obstruction is safe and reduces the need for surgery when conservative treatment fails.  相似文献   
45.
Law WL  Chu KW 《World journal of surgery》2002,26(10):1272-1276
This study reviewed the local recurrence rate in patients who had undergone total mesorectal excision and double-stapling low anterior resection for mid and distal rectal cancers. It also aimed to identify risk factors for local recurrence through univariate and multivariate analyses. Consecutive patients with rectal cancers within 12 cm of the anal verge treated with total mesorectal excision and double-stapling low anterior resection from August 1993 to December 2000 were studied. The demographic data, operative details, tumor characteristics, and follow-up data were collected prospectively. Factors that might affect the local recurrence rate were analyzed with univariate and multivariate analyses. A total of 270 patients were included in the study (156 men, 114 women). The mean +/- SD age was 64.83 +/- 11.27 years. The mean +/- SD level of the tumor was 7.17 +/- 1.90 cm. All anastomoses were performed within 5 cm of the anal verge. During the mean follow-up of 35.5 months, 12 patients developed local recurrence. The 5-year actuarial local recurrence rate was 7.3%. The presence of lymphovascular invasion and the resection margin of < or = 1 cm were found to be risk factors for local recurrence in the univariate analysis. In the multivariate analysis, the presence of lymphovascular invasion was the only independent factor for local recurrence. In the group of patients with lymphovascular invasion, proximal tumors (6-12 cm from the anal verge) were shown to have a significantly lower local recurrence than those within 6.1 cm from the anal verge (4.2% vs. 37.8%; p <0.001). Low anterior resection performed with double stapling and total mesorectal excision achieved a local recurrence rate of 7.3%. The presence of lymphovascular invasion was the only independent risk factor for local recurrence. A high local recurrence rate was associated with distal cancers (? 6 cm from the anal verge) with lymphovascular invasion. Adjuvant therapy for local control should be considered for this subgroup of patients.  相似文献   
46.
Aim The aim of this study was to evaluate the outcomes of self‐expanding metallic stent (SEMS) placement in acute left‐sided large‐bowel obstruction. Method From 1997 to 2008, 130 patients [mean 67 (SD 14.7)] underwent SEMS insertion for acute left‐sided large‐bowel obstruction. One‐hundred and one procedures were palliative, and 29 patients underwent stent insertion as a bridge for surgery. The success rate and the outcome were analysed. Results The chief causes of obstruction were primary (67%) and recurrent (16%) colorectal carcinoma. The success rate was 88% after insertion of the first stent. In nine patients, insertion of a second stent was required. Complications occurred in 20% of the insertions, with migration (10.8%) being the most common. Perforation occurred in two patients and one developed a colovesical fistula. In patients with palliative stenting, 14 (13.9%) required subsequent surgery, with a stoma placed in all except three. Among the 29 patients who underwent SEMS insertion as a bridge to surgery, subsequent surgical resection was performed in 26 patients at a mean interval of 12 days (SD 18.0). Primary anastomosis was performed in 24 patients. The mean survival for those who underwent SEMS insertion as a bridge to surgery was 40 (95% confidence interval: 24–55) months. Conclusion SEMS placement is safe and effective in relieving acute left‐sided colonic obstruction. It allows subsequent definitive surgery on an elective setting and also serves as good palliation for advanced or disseminated disease.  相似文献   
47.
PURPOSE: Arterial occlusions of the small vessels of the forearm and hand may have the same consequences as arterial occlusions in the distal lower extremity. There is limited reported experience with the regional thrombolytic therapy in this setting. The authors reviewed their experience with thrombolytic therapy in acute and subacute arterial occlusions of the distal upper extremity to further clarify its role. MATERIALS AND METHODS: Twelve patients with acute or subacute arterial occlusions of the forearm and hand who had ischemic digits and were treated with regional urokinase infusion were identified retrospectively. Their medical and radiology records were reviewed. RESULTS: All 12 patients demonstrated angiographic improvement and 11 patients demonstrated clinical improvement after treatment. Tissue necrosis in four patients led to partial amputation of one digit in two patients and three digits in two patients. Three of these patients had category III ischemia at presentation. The level of resulting amputation was altered in all but one patient. Vasospasm was noted frequently but responded to vasodilators. No significant complications occurred. CONCLUSIONS: When therapeutic alternatives are limited to anticoagulation and expectant amputation, regional urokinase infusion can optimize distal runoff, obviate or improve the options for distal surgical bypass, and limit tissue loss.  相似文献   
48.
Recent studies have indicated that numerical chromosomal abnormalities including changes in p53 and cyclin D1 may be involved in Hurthle cell tumorigenesis. We analyzed a series of Hurthle cell neoplasms of the thyroid to evaluate the diagnostic and prognostic utility of numerical anomalies by DNA fluorescent probes for cyclin D1 and p53 gene loci and chromosomes 5, 7, 11, 12, 17, and 22. Interphase fluorescence in situ hybridization (FISH) analysis was performed on paraffin-embedded tissue sections from 10 Hurthle cell adenomas, 19 Hurthle cell carcinomas, and 7 normal thyroid tissues used as controls. Directly labeled fluorescent DNA probes for the centromere region of chromosomes 7, 11, 12, and 17 and locus-specific probes for chromosomes 5 and 22, cyclin D1, and p53 were utilized for dual-probe hybridizations. Sixty percent (6 of 10) Hurthle cell adenomas and 63% (12 of 19) Hurthle cell carcinomas showed chromosome gains. Twenty percent (2 of 10) Hurthle cell adenomas and 26% (5 of 19) Hurthle cell carcinomas showed chromosome losses. Normal thyroid tissues used as controls showed no chromosomal abnormalities. Among Hurthle cell tumors with chromosomal abnormalities, adenomas averaged 2.7 gains and 0.3 losses per case, and carcinomas averaged 3.3 gains and 0.6 losses per case. The two adenomas with chromosome losses each showed loss of one chromosome, whereas the five carcinomas with losses averaged 1.8 losses per case. Chromosome 22 was the most common loss identified, occurring in three of the 11 patients who died of disease. These results indicate that chromosomal imbalances as gains are common in both benign and malignant Hurthle cell neoplasms, but Hurthle cell carcinomas tend to have more chromosome losses than adenomas. Among Hurthle cell carcinomas in this study, chromosome losses were identified only from patients who died of disease. The loss of chromosome 22 may have prognostic value in Hurthle cell carcinoma of the thyroid.  相似文献   
49.
Summary  Haemorrhage from rupture of petrous ICA aneurysm can be life threatening and emergency treatment is required. We report 2 cases of radiation-induced petrous internal carotid artery (ICA) aneurysm presenting with acute haemorrhage (epistaxis and otorrhagia) after radiotherapy (RT) for nasopharyngeal carcinoma (NPC). Both patients had a history of RT treatment for NPC. The first patient, a 54-year-old man, presented with sudden severe epistaxis and haemorrhagic shock. The second patient, a 35-year-old man, presented with episodes of severe otorrhagia. The first patient was immediately resuscitated. Obliteration of the aneurysm was performed by endovascular occlusion of the ICA with Guglielmi detachable coils and fibered platinum coils. For the second patient, the aneurysm was treated by deploying a self-expandable stent across the aneurysm neck. In an emergency situation, ruptured petrous ICA aneurysm can be treated with endovascular occlusion of the ICA with microcoils if there is a good collateral blood flow. Alternatively, the aneurysm can be treated by deployment of a stent, which can induce stasis and eventual thrombosis of the aneurysm.  相似文献   
50.
Malignant melanoma in a burn scar   总被引:1,自引:0,他引:1  
Cancers of various sorts are occasionally encountered in burn scars. These lesions are usually squamous cell carcinomas, and the burn scars are usually old. Very rarely, malignant melanoma is encountered. An 87-year-old nursing home patient who had been burned by a lightening strike at age 16 was evaluated. She had sustained a wound covering 2% or 3% of her body surface involving her neck and the upper portion of her anterior trunk that had required several grafts. A lesion was noted over the suprasternal notch approximately 3 months before admission. The biopsy was reported as malignant melanoma. She was subsequently treated by wide reexcision with an associated Z-plasty for neck release. Because of the patient's age and the presence of four areas of regional lymph nodes nearby into which metastasis might spread, no lymph node dissections were carried out. The specimen from the reexcision was reported as squamous cell carcinoma in situ, melanoma in situ, and multinucleated giant cell reaction, acute and chronic infiltrates. The wound margins were clear.  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