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   5163篇
  免费   223篇
  国内免费   121篇
耳鼻咽喉   37篇
儿科学   162篇
妇产科学   76篇
基础医学   541篇
口腔科学   61篇
临床医学   424篇
内科学   1437篇
皮肤病学   109篇
神经病学   405篇
特种医学   487篇
外国民族医学   1篇
外科学   575篇
综合类   45篇
预防医学   378篇
眼科学   66篇
药学   331篇
中国医学   3篇
肿瘤学   369篇
  2023年   19篇
  2022年   7篇
  2021年   31篇
  2020年   20篇
  2019年   31篇
  2018年   54篇
  2017年   23篇
  2016年   41篇
  2015年   51篇
  2014年   39篇
  2013年   76篇
  2012年   372篇
  2011年   396篇
  2010年   137篇
  2009年   119篇
  2008年   345篇
  2007年   409篇
  2006年   366篇
  2005年   392篇
  2004年   335篇
  2003年   302篇
  2002年   294篇
  2001年   207篇
  2000年   288篇
  1999年   151篇
  1998年   109篇
  1997年   98篇
  1996年   108篇
  1995年   71篇
  1994年   64篇
  1993年   67篇
  1992年   14篇
  1991年   31篇
  1990年   26篇
  1989年   49篇
  1988年   40篇
  1987年   57篇
  1986年   29篇
  1985年   45篇
  1984年   19篇
  1983年   16篇
  1982年   25篇
  1981年   20篇
  1980年   30篇
  1979年   9篇
  1978年   11篇
  1977年   16篇
  1976年   26篇
  1975年   15篇
  1970年   3篇
排序方式: 共有5507条查询结果,搜索用时 14 毫秒
21.
22.
Brown's syndrome is generally an isolated clinical condition. The authors observed a girl with a right Brown's syndrome and a rare condition due to an interstitial deletion of chromosome 17, known as Smith-Magenis syndrome. A wide spectrum of congenital disorders have been reported in Smith-Magenis syndrome, but never Brown's syndrome.  相似文献   
23.
OBJECTIVE: In addition to sex steroids, prolactin (PRL) may also stimulate prostate cancer growth. Abnormally high blood levels of PRL have been noted in metastatic prostate cancer patients. However, most studies have been limited to the evaluation of basal levels of PRL rather than to investigate its secretion in response to classical endocrine dynamic tests. This study was carried out to analyze PRL secretion in metastatic prostate cancer patients both at basal conditions and in response to L-Dopa and metoclopramide, which represents the most classical inhibitory and stimulatory tests for PRL secretion, respectively. METHODS: The study included 12 patients with metastatic prostate cancer. On separate occasions, PRL secretion was evaluated in response to L-Dopa (500 mg orally) and to metoclopramide (10 mg i.v. as a bolus). Serum levels of PRL were measured by RIA. RESULTS: Mean PRL concentrations significantly increased after metoclopramide administration, even though no PRL response occurred in 6 of 12 patients. L-Dopa was unable to reduce PRL levels, which, in contrast, paradoxically significantly increased in response to L-Dopa, with mean values comparable to those achieved after metoclopramide injection. CONCLUSION: By showing a paradoxical stimulatory effect of L-Dopa on PRL secretion and a lack of response to metoclopramide in some patients, this study would suggest the existence of evident alterations in the neuroendocrine regulation of PRL release in advanced prostate cancer.  相似文献   
24.
BACKGROUND: Conjugated linoleic acid (CLA) is a mixture of isomers of linoleic acid with conjugated double bonds that constitutes the most abundant fatty acid with conjugated dienes (CDs) in humans. CLA, erroneously considered in the past as a product of lipoperoxidation, has a dietary origin and has shown to possess anticarcinogenic and anti-atherogenic activity, mainly in animal studies. CLA can be metabolized to conjugated linolenic acid (CD18:3) and to conjugated eicosatrienoic acid (CD20:3) and these metabolites may be implicated in CLA activity. Because of the presence of dyslipidemia and the high incidence of cardiovascular and neoplastic diseases in uremic patients, we evaluated CLA and its metabolites in these patients in order to evaluate their metabolism and site distribution. METHODS: We measured CLA, CD18:3, CD20:3, CD fatty acid hydroperoxides (lipoperoxidation products), and linoleic acid in the plasma, adipose tissue, and red blood cell (RBC) membranes by using high-pressure liquid chromatography in the following groups: (1) 23 chronic renal failure (CRF) patients with creatine clearance (CCr)> 10 mL/min (26.2 +/- 16.7); (2) 21 end-stage CRF patients in conservative treatment with CCr <10 mL/min (6.8 +/- 1.8); (3) 30 hemodialysis (HD) patients; and (4) 30 healthy controls. RESULTS: The incorporation of CLA, CD18:3, and CD20:3 in RBC membranes was significantly reduced in group 1 and was even more reduced in groups 2 and 3. CLA significantly increased both in the plasma and adipose tissue of end-stage CRF patients only. CD18:3 and CD20:3 did not change in the plasma and adipose tissue of any group. No significant changes in linoleic acid and CD fatty acid hydroperoxides were found. CONCLUSIONS: The alterations of CD in CRF patients are not due to lipoperoxidation. The increased levels of CLA in plasma and adipose tissue of end-stage CRF patients may be due either to a reduced metabolization of CLA to CD18:3 and CD20:3, or to an altered site distribution with reduced incorporation in cellular membranes and accumulation in the plasma and adipose tissue. The clinical significance of these changes remains to be investigated.  相似文献   
25.
26.
BACKGROUND: Nowadays the only indications to truncal vagotomy is recurrent ulceration after previous gastric surgery. Truncal vagotomy allows us to obtain a reduction in acid production and to promote ulcer healing, but this technique causes pylorospasm in about 20% of cases and this requires further synchronous or metachronous pyloric drainage procedure. For this reason, videothoracoscopic truncal vagotomy is reserved to patients with gastroresection. METHODS: The authors describe 15 patients treated with videothoracoscopic truncal vagotomy. In 12 patients, a gastrojejunostomy was done according to Roux technique in 2 patients, a reconstruction according Billroth II technique and in 1 patient, a gastroduodenostomy according to Billroth I technique. RESULTS: Videothoracoscopic bilateral truncal vagotomy was done in all patients; operation time was 45 minutes. During the postoperative period there were no complications. No patients underwent medical therapy for peptic ulcer. Only in 12 patients was it possible to execute an endoscopic follow-up in a period of 3 to 4 years. In all patients the ulcer was completely healed. CONCLUSIONS: Complete vagotomy in patients who present with recurrent gastrointestinal bleeding after previous gastroresection, is associated with significant risks. Videothoracoscopic bilateral truncal vagotomy as a simple and efficient procedure seems to be an alternative treatment for the management of recurrent ulceration after previous gastric surgery for peptic disease.  相似文献   
27.
HYPOTHESIS: Unilateral truncal thoracoscopic splanchnicectomy (TS) provides safe and effective treatment for pain relief in patients with unresectable pancreatic cancer. DESIGN: Before-and-after trial of 24 patients undergoing 25 TS procedures. SETTING: Surgical unit at a university teaching hospital. PATIENTS: A consecutive sample of 24 patients with severe pain due to unresectable (primary or recurrent) pancreatic cancer refractory to drug therapy and with a life expectancy of less than 6 months. INTERVENTION: The key point of the reported operation is intrathoracic carbon dioxide insufflation, which allows a more distal division of the greater splanchnic nerve and a 2-port technique. MAIN OUTCOME MEASURES: Pain and the effect of this symptom on quality of life were assessed before and after TS using a 10-point visual analog pain scale (VAS) and the Nottingham Health Profile questionnaire, respectively. RESULTS: Four TS procedures were technical failures because of pleural adhesions. One patient required a contralateral procedure 12 weeks after TS. Mean (+/- SD) preoperative VAS basal score was 7.4 +/- 1.7. Twenty-four hours after TS, it was reduced to 0.6 +/- 1.0. Significant reduction of VAS scores persisted over the first 3 months after TS (P<.001). Recurrence of pain of low intensity (mean VAS basal score, 4.2) was observed in 8 patients. Significant improvement (P<.001) in each area covered by the Nottingham Health Profile questionnaire was reported at 1 month after TS. CONCLUSION: Thoracoscopic splanchnicectomy offered substantial short-term relief of pain in patients with unresectable pancreatic cancer, and significantly ameliorated the quality of their residual life.  相似文献   
28.
Thyroid microcarcinoma is nowaday defined as a tumor of one centimeter or less in the maximum diameter. It occurs in less than five per cent of all thyroid carcinomas. In personal experience four thyroid microcarcinomas have been found in specimens from 121 thyroidectomies and have been retrospectively reviewed clinical data and the long term follow-up of the patients. Total thyroidectomies nor prophylactic lymphadenectomies were never performed. All patients at present are well. Our purpose was to focus on the current surgical treatment of microcarcinoma. Many hypotheses are done to explain pathogenesis and fairly good prognosis of thyroid microcarcinomas, without univocal conclusions. Almost all authors agree that microcarcinoma of the thyroid gland is a low-aggressive tumor, with good biological behaviour, but the therapeutic strategies are not codified yet. Particularly, doubt still exists about the choice between total thyroidectomy and more conservative procedure, and lymphadenectomy, especially when tumor is found in specimens after surgery for benign disease. In conclusion, in our opinion conservative management is the best choice, provided that the patient is included in a correct long-term follow-up.  相似文献   
29.
30.
Silver-Russell syndrome (SRS) is clinically variable although most cases have several common signs. Different chromosomes and chromosomal regions have been associated with SRS. Maternal uniparental disomy (UPD) of chromosome 7 is responsible for 5-10% of cases, probably because of an imbalance between maternal and paternal imprinted genes and more recently maternal duplication or epimutations in the 11p15 imprinted region have been described. To date, only two patients with maternal UPD7 and a mosaic condition for a supernumerary ring 7 marker have been reported, and we here report a further case. Standard QFQ banding of lymphocytes as well as fluorescence in-situ hybridization analyses were performed to identify and characterize the supernumerary marker. UPD testing was performed on both the patient's and parents' DNA using chromosome 7 microsatellite markers. The patient demonstrated a ring in about 4% of the analysed cells. On the basis of cytogenetic and molecular results, break points were tentatively identified as 7p11.2 and 7q21. Maternal hetero-/iso-UPD and a paternal origin for the supernumerary ring were demonstrated. Clinical data comparison between our patient who has a SRS phenotype and cases with hetero-/iso-UPD7 mat and mosaicism for a paternally derived chromosome 7 ring and previously reported ring 7 cases suggest that the SRS phenotype is probably because of the UPD rather than to the partial trisomy.  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