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   230943篇
  免费   54293篇
  国内免费   10312篇
耳鼻咽喉   2745篇
儿科学   6519篇
妇产科学   2424篇
基础医学   30848篇
口腔科学   7565篇
临床医学   31222篇
内科学   43653篇
皮肤病学   9027篇
神经病学   19638篇
特种医学   8039篇
外国民族医学   74篇
外科学   29129篇
综合类   30389篇
现状与发展   33篇
一般理论   43篇
预防医学   16423篇
眼科学   4744篇
药学   23216篇
  153篇
中国医学   11533篇
肿瘤学   18131篇
  2024年   530篇
  2023年   2098篇
  2022年   5383篇
  2021年   8267篇
  2020年   10353篇
  2019年   14692篇
  2018年   14498篇
  2017年   15762篇
  2016年   16009篇
  2015年   18106篇
  2014年   19763篇
  2013年   20324篇
  2012年   16454篇
  2011年   17522篇
  2010年   18357篇
  2009年   13314篇
  2008年   11754篇
  2007年   10380篇
  2006年   9742篇
  2005年   8561篇
  2004年   6832篇
  2003年   6433篇
  2002年   5765篇
  2001年   4641篇
  2000年   4067篇
  1999年   3176篇
  1998年   1688篇
  1997年   1687篇
  1996年   1294篇
  1995年   1100篇
  1994年   955篇
  1993年   636篇
  1992年   825篇
  1991年   711篇
  1990年   610篇
  1989年   553篇
  1988年   436篇
  1987年   429篇
  1986年   327篇
  1985年   267篇
  1984年   200篇
  1983年   125篇
  1982年   93篇
  1981年   111篇
  1980年   73篇
  1979年   96篇
  1978年   68篇
  1977年   50篇
  1976年   52篇
  1974年   57篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
OBJECTIVE: The C2A domain of Synaptotagmin I is a molecular probe for the specific imaging of cell death. Here we test the hypothesis that the uptake of 99mTc-C2A in the acute phase of an infarction is associated with cardiac dysfunction in follow-ups. METHODS: The left coronary artery was occluded in Sprague-Dawley rats for 0, 10, 20, and 30 min. 99mTc-C2A was injected intravenously at 2 h of reperfusion. Anterior planar images were acquired with one million counts on a gamma camera 3 h after injection. 99mTc-C2A uptake was calculated as the total counts in the left ventricle region minus blood pool signal. The in-vivo signal detected was correlated with wall motion score index at 1 and 3 weeks follow-ups measured by echocardiography. RESULTS: 99mTc-C2A uptake was higher with increased ischemic time (2244+/-852, 4054+/-1223, and 6178+/-1451 for 10, 20, and 30 min ischemia, analysis of variance P<0.001). A significant correlation was found between 99mTc-C2A uptake and wall motion score index at 1 week (R=0.800, P=0.0006) and 3 weeks (R=0.810, P=0.0008). CONCLUSION: In this ischemia/reperfusion model, 99mTc-C2A uptake in the acute phase was associated with functional abnormality at 1 and 3 weeks. This demonstrates the potential diagnostic and prognostic value of 99mTc-C2A as a novel imaging agent.  相似文献   
62.
1 The internal anal sphincter (IAS) has a spontaneous tone and is the main contributor to the maintenance of faecal continence. The spontaneous resting tone exhibited by the sphincter can be modified by neurotransmitters from the autonomic and enteric nervous systems. 2 In this review, the influence of the sympathetic and parasympathetic nervous systems on IAS tone are discussed and the putative roles of nitric oxide, carbon monoxide, vasoactive intestinal peptide and adenosine triphosphate in non‐adrenergic non‐cholinergic transmission are considered. 3 Faecal incontinence is a common condition that places a heavy financial burden on the health service and severely affects patients’ quality of life. Resting anal pressure is reduced in patients with faecal incontinence and agents that increase sphincter tone tend to relieve symptoms. The results of clinical studies of the use of phenylephrine to treat faecal incontinence are reviewed. 4 It is concluded that the IAS is a potential target for drug development for the treatment of faecal incontinence.  相似文献   
63.
64.
The first universal hepatitis B vaccination program for newborns in the world was launched in Taiwan in July 1984. Most studies on the effectiveness of hepatitis B vaccination focused on the seroprevalence of HBs Ag among children under 14 years old. Only few studies focused on the seropositivity of anti-HBs among adolescents aged 15–18 years old. The present study aimed to evaluate the impact of the nationwide hepatitis B vaccination program on the immunity to HBV infection and the necessity of boost among adolescents. In this study including eight annual seroprevalence surveys from 2000 to 2007, 2342 college entrants (1589 15-year-olds in group I and 753 18-year-olds in group II) and 1851 university freshmen (18-year-olds in group III) participated. Subjects identified anti-HBs, HBs Ag and anti-HBc negative were given boost three doses of HBV vaccine. The HBs Ag seroprevalence was 11.6%, 3.5% and 1.0% for participants who were born before 1984, 1984–1986 and after 1986. The anti-HBs-seropositive rates were significantly higher in group II (83.1%) than in group I (53.0%) and group III (53.5%). All 572 participants who were seronegative for anti-HBs, HBs Ag and anti-HBc became anti-HBs-seropositive after catch-up vaccination. It is concluded that the anti-HBs-seropositive rate decreased to 50% in 15 years after vaccination, and boost vaccination was 100% effective. The necessity and age for boost among anti-HBs negative adolescents and the timing of the first immunization should be further evaluated.  相似文献   
65.
腮腺良性和恶性多形性腺瘤的超声研究   总被引:1,自引:0,他引:1  
目的研究腮腺良性和恶性多形性腺瘤的超声特点,为临床医师诊治提供有效依据。方法选取腮腺良性多形性腺瘤患者79例和恶性多形性腺瘤患者15例,对其肿块的大小、硬度、内部回声、彩色多普勒血流显像(CDFI)特点结合病理学诊断进行对照研究。结果恶性多形性腺瘤的声像图特点与良性多形性腺瘤相似,但其肿瘤相对较大,质地更硬,内部回声分布更紊乱。不同性质的肿瘤的大小和质地有显著性差异,(P<0.01)。结论多形性腺瘤的超声诊断主要依据二维图像之特点。当多形性腺瘤大于3.0 cm,硬度较硬,内部回声分布不均多提示恶性。  相似文献   
66.
随着高新技术的发展和人们对生物医学认识的不断提高和更新,近年来医学基础研究呈现出飞跃式发展。人们利用不断发展开发的新技术,对人类各种疾病的发生发展进行了深入的研究和探讨。以下就泌尿系肿瘤基础研究的热点及我国存在的问题做一简要介绍。  相似文献   
67.
Background The incidence rate of incisional hernias after open surgery has been reported to be higher than that of port site hernias after laparoscopic surgery. No studies have compared the costs for the health care system in treating those two types of hernia. Methods A systematic review was conducted to obtain the baseline data, and a decision analysis model was created to simulate the occurrence and recurrence of incisional and port site hernias. Results The overall risk of having incisional hernias was eight-times higher than that of having port site hernias (7.4% vs 0.9%). A cost savings of £93 per patient can be generated for the health care system in the UK. Similar results were obtained for Germany, Italy and France. Conclusions The additional treatment costs for incisional hernia should be taken into account when the costs of a surgery performed by open approach are compared with by laparoscopy.  相似文献   
68.
Purpose Parathyroid carcinoma (PC) is rare and accounts for less than 1% of all cases of primary hyperparathyroidism (PHPT). The definitive histopathologic diagnosis of PC requires unequivocal invasion or metastasis which may be absent at first presentation. As a result, many cases of PC can only be diagnosed retrospectively. Parafibromin is the protein encoded by HRPT2 which is mutated and not expressed in many parathyroid carcinomas. Given that PCs generally weigh more than parathyroid adenomas (PA)s, we hypothesized that amongst large PAs there may be a high incidence of occult PC which could be identified by negative staining for parafibromin. Methodology 57 parathyroid glands weighing greater than 2 grams excised from 1998–2006 were identified from the University of Sydney Endocrine Surgical Database. Two specimens with a histopathologic diagnosis of PC were excluded. Immunohistochemical staining for parafibromin was performed on the remaining 55 PAs. Results Of the 55 specimens stained for parafibromin only one definite negative stain was detected. This case was originally classified as an “atypical adenoma” because it showed nuclear and architectural atypia without unequivocal evidence of invasive growth. In view of the negative staining for parafibromin it therefore probably represents occult carcinoma. There has been no evidence of recurrence or metastasis after 6.5 years. Conclusions Complete loss of staining for parafibromin is very rare in giant parathyroid adenomas suggesting that occult carcinoma is equally rare. As a result routine immunohistochemical staining for parafibromin does not appear to be an effective screening test for carcinoma in large PA without histopathologic features of PC.  相似文献   
69.
Purpose To demonstrate that laparoscopic adjustable gastric banding may promote oesophageal dilatation or interfere with oesophageal motility. Methodology We report a case of a 67 year old female with a complex medical history who developed secondary achalasia from a slipped laparoscopic adjustable gastric band for weight loss. This led to recurring episodes of aspiration pneumonia requiring multiple admissions at North Shore Hospital, Auckland, New Zealand. Results A decision was made to remove the gastric band, five years after its initial insertion. At one month follow up, she was swallowing normally and oesophageal manometry had returned to normal. Conclusion Oesophageal dysmotility is sometimes seen in patients who have bands that are adjusted too tightly or in whom the band has slipped. This can lead to serious complications if unrecognized and incorrectly treated. Oesophageal symptoms in patients with adjustable bands must be considered secondary to the band until proven otherwise ie removal of the band or complete deflation.  相似文献   
70.
有限内固定结合外固定支架治疗胫骨远端骨折   总被引:5,自引:2,他引:3  
目的探讨有限内固定结合Hybrid外固定支架治疗胫骨远端骨折的疗效。方法从2003年1月~2005年7月,使用Hybird外固定支架治疗胫骨远端骨折21例,按AO分类:A1型4例;A2型5例;A3型4例;C1型2例;C2型3例;C3型3例,其中开放性骨折8例,手术采用有限切开,骨片钉固定,Hybrid外固定支架不跨踝关节固定。结果术后21例均获随访,平均随访时间12.3个月,骨折平均愈合时间7.6个月。功能评定采用Bone的踝关节活动度进行评价,优良率达76%。结论Hybrid外固定支架设计合理并能维持骨干的轴线,骨片钉能很好的固定骨折块,同时避免了软组织的并发症,可使踝关节早期活动,防止踝关节僵硬,因而是治疗胫骨远端骨折有效的方法之一。  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