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   386篇
  免费   31篇
  国内免费   11篇
耳鼻咽喉   1篇
儿科学   33篇
妇产科学   3篇
基础医学   28篇
口腔科学   6篇
临床医学   41篇
内科学   51篇
皮肤病学   8篇
神经病学   4篇
特种医学   132篇
外科学   44篇
综合类   6篇
预防医学   10篇
药学   19篇
  1篇
肿瘤学   41篇
  2024年   1篇
  2022年   2篇
  2021年   4篇
  2020年   2篇
  2019年   5篇
  2018年   15篇
  2017年   3篇
  2016年   4篇
  2015年   4篇
  2014年   3篇
  2013年   8篇
  2012年   7篇
  2011年   7篇
  2010年   3篇
  2009年   13篇
  2008年   9篇
  2007年   16篇
  2006年   11篇
  2005年   2篇
  2004年   5篇
  2003年   3篇
  2002年   2篇
  2001年   4篇
  2000年   4篇
  1999年   9篇
  1998年   18篇
  1997年   15篇
  1996年   26篇
  1995年   15篇
  1994年   21篇
  1993年   16篇
  1992年   5篇
  1991年   7篇
  1990年   8篇
  1989年   19篇
  1988年   17篇
  1987年   22篇
  1986年   12篇
  1985年   10篇
  1984年   9篇
  1983年   12篇
  1982年   10篇
  1981年   9篇
  1980年   8篇
  1979年   5篇
  1978年   1篇
  1977年   6篇
  1976年   9篇
  1975年   2篇
排序方式: 共有428条查询结果,搜索用时 31 毫秒
11.
12.
The amino acid intermediate homocysteine (Hcy) is formed during the metabolism of methionine to cysteine. Hyperhomocysteinemia (HHcy) is recognized as an independent risk factor for coronary atherosclerosis. The circulating levels of total Hcy (tHcy) can increase due to intake of foods rich in methionine or deficiencies of vitamins such as folate, pyridoxine and cyanocobalamin, which are required for the metabolism of Hcy. In addition, mutations in the genes coding for Hcy metabolizing enzymes can contribute to an increase in tHcy levels. Clinical and epidemiological studies have shown that an elevated level of tHcy measured in serum or plasma is a strong predictor of cardiovascular disease risk, which appears to be greatest in patients who have HHcy following a methionine load. Intimal hyperplasia (IH) (intima/media [I/M] ratio) is the universal response of a vessel to injury and may result in vasoconstriction when left unattended. The effect of dietary HHcy on balloon catheter-injured carotid artery and its modulation (if any) by the peroxisome proliferator-activated receptor agonist gamma rosiglitazone was evaluated in 12-week-old female Sprague-Dawley rats fed either a control diet or a diet containing 1% L-methionine. Once the rats were established on the diet, the group that was fed 1% L-methionine was further subdivided and either given an aqueous preparation of 3 mg/kg/day rosiglitazone or the vehicle via oral gavage for one week. This was followed by surgically injuring the left carotid artery using a Maverick Over-The-Wire catheter (2.0 mm × 20 mm, 3.2F; Boston Scientific, USA). The rats were continued on their respective diets and drug regimen for 21 days postsurgery. On day 22 of the procedure, the rats were sacrificed for collection of blood, the carotid arteries and liver for biochemical and histological evaluation. Compared with controls there was a significant increase in both tHcy levels and I/M ratio in the rats fed 1% L-methionine (5.4±0.28 μM versus 32.8±3.01 μM, P<0.002; and 0.175±0.05 versus 1.05±0.23, P<0.005, respectively). The effect of rosiglitazone in rats fed the control diet was not prominent. On the other hand, administration of rosiglitazone to the rats on the 1% L-methionine diet significantly reduced the levels of serum tHcy (16.6±2.1 μM versus 32.8±3.01 μM, P<0.001); however, the tHcy levels remained significantly elevated compared with animals on the control diet (P<0.002). The group receiving the L-methionine diet plus rosiglitazone had an inhibition in the development of IH compared with those receiving the L-methionine diet alone (I/M of 0.278±0.041 versus 1.05±0.23, P<0.01). Moreover, the development of IH in the group receiving the L-methionine diet plus rosiglitazone treatment was not significantly different from that observed in the group on the control diet without rosiglitazone (0.278±0.041 versus 0.175±0.05, respectively). These findings may have important implications in deciphering the molecular mechanisms involved in the augmentation of IH in HHcy and modulation of this process by rosiglitazone.  相似文献   
13.
[目的]调查产后抑郁症患者的现状及需求,探讨预防措施。[方法]定性与定量研究相结合,定性采用专题小组讨论和半结构性访谈,12人参加专题讨论、9人半结构性访谈;定量研究随机抽取本市各社区产后42d的产妇776例行问卷调查。[结果]产妇月子期间常发生头疼、恶心、焦虑、恐惧、失眠以及照顾新生儿困难;半结构性访谈中有1产妇处于产后抑郁症的临界,EPDS量表测定为12分;776例产妇月子里有身心健康问题者692例,求助者91.0%,其中需要社区护理人员帮助的71.7%,实际寻求帮助仅12.7%。[结论]预防产后抑郁症应实行社区医护人员培训与产后访视人员的准入制度,采取社区医护干预的三级预防,同时拓展社区产后保健服务的内涵。  相似文献   
14.
The purpose of this study was to determine the outcome of surgery for patients with recurrent gastric or gastroesophageal cancer. We queried records from 7,459 patients who presented with gastric or gastroesophageal cancer to our institution from 1973 through 2005 to identify those for whom resection of recurrent disease had been attempted. We assessed the associations between various clinicopathologic factors and resectability with logistic regression analysis and between clinicopathologic factors and overall survival (OS) with the Cox proportional hazards model. Sixty patients underwent attempted resection for recurrent cancer. In 31 cases (52%), recurrent disease proved unresectable at laparotomy. Factors associated with the ability to undergo re-resection included neoadjuvant treatment prior to initial resection [odds ratio (OR) 12.2, 95% confidence interval (CI) 1.9–75.6] and having an isolated local recurrence (OR 5.1, 95% CI 1.3–20.5). Of the 29 patients who underwent re-resection, 14 required adjacent organ resection, and 6 required interposition grafting. Three- and 5-year OS rates for all 60 patients were 21% and 12%, respectively; median follow-up time was 23 months. Median OS for patients undergoing resection was 25.8 months (95% CI 17.1–49.8) versus 6.0 months (95% CI 4.0–10.5) for unresectable patients (P < 0.001). Initial tumor location at the gastroesophageal junction was associated with diminished OS [hazard ratio (HR) 2.8, 95% CI 1.2–6.5] and ability to undergo resection of recurrence was associated with improved OS (HR 0.2, 95% CI 0.1–0.6). We conclude that surgical resection of select patients with recurrent gastric or gastroesophageal cancer can result in improved OS but often requires adjacent organ resection or interposition graft placement.  相似文献   
15.
目的:评估人工流产(指手术流产)对乳腺癌危险性的可能影响。方法:研究在上海267040例妇女的一项乳房自我检查随机试验的队列人群中进行,由队列研究和巢式病例对照研究两部分组成。结果:依据基线调查表采集的资料分析,人工流产不增加乳腺癌危险性。调整潜在的混淆因素后,OR=1.06(95%CI:0.91~1.25)。人工流产次数增加无危险性趋势增加。从更详细的652例乳腺癌病例和694例对照资料分析,得出相似的结果。人工流产发生在首次生育后不增加危险性;少数妇女在首次生育前人工流产以及妊娠13周后人工流产,虽然被观察到危险性有增加,但无显著性统计学意义。结论:在中国,人工流产不是乳腺癌发生的重要原因。  相似文献   
16.
17.
1. 5-Hydroxytryptamine (5-HT) exerts both contractile and relaxant effects in the marmoset isolated aorta, actions that are unaffected by the 5-HT2 antagonist ketanserin. The aim of the present study was to define the receptors mediating the contractile activity of 5-HT in the marmoset aorta.
2. Contractile responses were elicited in aortic rings that were either: (i) precontracted submaximally with the thromboxane A2 agonist U44069 in order to amplify the responses; or (ii) exposed to N ω-nitro- L -arginine (100 μmol/L) plus LY 53857 (0.1 μmol/L; a 5-HT2 receptor antagonist shown previously to inhibit relaxation). The effect of 5-HT on adenosine 3',5'-cyclic monophosphate (cAMP) formation was also investigated.
3. The effects of agonists and antagonists comprised: (i) agonist potencies in the order 5-carboxamidotryptamine > 5-HT > sumatriptan > 8-hydroxy-2-(di- n -propylamino)tetralin; (ii) inhibition of contractile action of 5-HT by the 5-HT1D antagonist GR 127935; (iii) a contractile response to methysergide; (iv) a lack of effect of tropisetron, an antagonist of 5-HT3 and 5-HT4 receptors; and (v) inhibition of forskolin-stimulated cAMP formation by 5-HT (in the presence of LY 53857), indicative of negative coupling to adenylate cyclase.
4. The above effects fulfil the criteria for a 5-HT1-like receptor. In view of the previous finding that this contractile response is insensitive to ketanserin, it is concluded that the contractile effects of 5-HT in the marmoset aorta are mediated exclusively by a 5-HT1-like receptor.  相似文献   
18.
19.
Zervos EE  Badgwell BD  Burak WE  Arnold MW  Martin EW 《Surgery》2001,130(4):636-43; discussion 643-4
BACKGROUND: The purpose of this study was to determine the role of fluorodeoxyglucose positron emission tomography (PET) in localizing disease in patients with colorectal cancer with radiologically occult symptomatology or increases in carcinoembryonic antigen (CEA) level. METHODS: Two hundred seventy-seven patients with colorectal cancer underwent PET scanning between November 1998 and September 2000 prompted by (1) increasing CEA level and nondiagnostic imaging or (2) symptoms with normal CEA level and nondiagnostic imaging. PET results were correlated with operative findings/histology, clinical follow-up data, and CEA level to determine PET's accuracy in determining the source of symptoms or CEA. RESULTS: Fifteen patients had increasing CEA levels, and 14 had abnormal PET. Two of these 14 were denied exploration because PET suggested widely metastatic disease. Nine patients underwent exploration with curative intent. In 1 patient, recurrence was not pathologically confirmed (false-positive rate, 8%). Two had disease beyond that predicted by PET, and 6 underwent complete resection and normalized their CEA levels. Four symptomatic patients with normal CEA levels and negative x-rays had abnormal PET; at exploration, 3 had no evidence of recurrence. CONCLUSIONS: PET imaging can often accurately localize the source of radiologically occult increases in CEA level and select that subset of patients eligible for therapeutic laparotomy. Symptomatic, PET-positive patients with normal CEA levels frequently undergo nontherapeutic laparotomy, and PET findings should be interpreted with caution in these patients.  相似文献   
20.
美国约有30%的糖尿病患者(约620万人)被漏诊。超过25%的新诊断糖尿病患者已经患有糖尿病视网膜病变或出现微量白蛋白尿,这意味着患者在2型糖尿病发病和确诊之间被“忽视”了7年。有时发现在糖尿病前期,即空腹血糖(FPG)略有偏高(IFG,空腹血糖受损)或口服葡萄糖耐量试验(OGTT)略有偏高,甚至已存在微血管和大血管并发症。  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