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   11458篇
  免费   920篇
  国内免费   203篇
耳鼻咽喉   161篇
儿科学   324篇
妇产科学   168篇
基础医学   1558篇
口腔科学   393篇
临床医学   1020篇
内科学   2281篇
皮肤病学   311篇
神经病学   700篇
特种医学   582篇
外国民族医学   1篇
外科学   1495篇
综合类   361篇
现状与发展   1篇
预防医学   743篇
眼科学   293篇
药学   861篇
  1篇
中国医学   146篇
肿瘤学   1181篇
  2024年   10篇
  2023年   125篇
  2022年   268篇
  2021年   508篇
  2020年   312篇
  2019年   404篇
  2018年   422篇
  2017年   368篇
  2016年   461篇
  2015年   530篇
  2014年   591篇
  2013年   657篇
  2012年   936篇
  2011年   894篇
  2010年   528篇
  2009年   384篇
  2008年   634篇
  2007年   622篇
  2006年   559篇
  2005年   589篇
  2004年   491篇
  2003年   402篇
  2002年   345篇
  2001年   218篇
  2000年   206篇
  1999年   179篇
  1998年   76篇
  1997年   71篇
  1996年   50篇
  1995年   41篇
  1994年   49篇
  1993年   43篇
  1992年   71篇
  1991年   88篇
  1990年   48篇
  1989年   53篇
  1988年   48篇
  1987年   39篇
  1986年   32篇
  1985年   28篇
  1984年   13篇
  1982年   11篇
  1981年   12篇
  1979年   20篇
  1974年   11篇
  1973年   10篇
  1972年   13篇
  1970年   12篇
  1969年   11篇
  1966年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.

Chronic hepatitis B (CHB) has a wide range of outcomes depending on host immune responses mainly Toll-like receptors (TLRs) signaling and released cytokines. Toll-like receptor 2 (TLR2) single nucleotide polymorphisms (SNPs) and interleukin 6 (IL-6) may influence the course of CHB. We aimed to elucidate the relation between TLR-2 polymorphism, IL-6 profile, and CHB progression. We analyzed TLR-2 polymorphism (SNP; rs3804099) in 185 CHB patients and 60 controls using TaqMan allelic discrimination assay. Serum IL-6 levels were assessed by ELISA. IL-6 levels were considerably higher in active CHB and cirrhotic patients compared with inactive carriers and controls (P < 0.001). IL-6 showed positive correlation with ALT and advanced fibrosis in active CHB patients (r = 0.31, P = 0.02). A significant positive correlation was noticed between IL-6 and HBV DNA PCR in all CHB groups. TT genotype of rs3804099/TLR-2 was significantly more prevalent in inactive carriers compared to active hepatitis patients (P = 0.04, OR = 0.39 and 95% CI: 0.16–0.95). Both heterozygous CT and mutant TT genotypes were significantly more frequent among inactive carriers compared to cirrhotic patients (P = 0.01, OR = 0.33, 95% CI: 0.13–0.81 and P = 0.009, OR = 0.32, 95% CI: 0.13–0.77). TT genotype was significantly related to lower IL-6 levels in active hepatitis and cirrhotic groups (P = 0.005 and P = 0.001, respectively) showing that TLR mutations would be associated with milder hepatitis activity and lower possibility for disease progression. There may be a positive association between TLR2 rs3804099 polymorphism and hepatitis B activity. IL-6 is a good indicator of CHB disease progression.

  相似文献   
102.
The study's objectives were to determine the frequency of biological-risk accidents involving percutaneous exposure and to identify factors associated with underreporting. Two hundred fifty healthcare professionals from inpatient services at high risk for exposure at the Puerta del Mar University Hospital of Cádiz, Spain, participated in the study. A questionnaire was used to measure personal and work variables, the number of accidents suffered and reported in the last year, and the circumstances motivating the reporting or nonreporting. Two hundred thirty-two persons (92.8%) completed the questionnaire. The accident rate was 12 per 100,000 hours worked. Physicians were the most frequent accident victims (rate 22/100,000 hours). The general surgery and emergency services had higher rates than other services (rates 19.82 and 14.17, respectively). Sixty-six percent of the accidents were not reported to the register. The main predictors of the underreporting were length of professional service greater than 19 years, working in the surgery service, and the perception that the accidents did not involve health risk. The true accident rate was higher than that reflected in the Accident Register. Underreporting was high. The main variables associated with underreporting were length of professional service, work area or department, and perception of risk from the accident.  相似文献   
103.
A bleached sulfate integrated pulp and paper mill producing printing and writing paper from mixed tropical hardwood and bamboo was studied. The mill uses a “conventional bleaching sequence,” C-E-H1-H2, with an average molecular chlorine consumption of 50 kg per ton of air-dried pulp (ADP). The content of polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs) in the bleaching filtrate in terms of the nordic toxicity equivalent (N-TEQ) was 33.5, 1.15, 0.56, and 0.014 pg/L for the E, C, H1, and H2 bleaching stages, respectively. The corresponding PCDFs and PCDDs loads in ng/t ADP were in the same ranking, i.e., 670, 69, 11.2, and 0.28, respectively. The congener and isomeric pattern of PCDFs and PCDDs of the bleaching filtrate and the bleached pulp was found to be typical for the chlorine bleaching plant effluent. The obtained dioxin load formed in the mill is in agreement with Western studies for the given multiple chlorine of 0.21–0.23. The load is, however, lower than reported discharges from Scandinavian mills using 1980s bleaching technologies, but substantially higher than the discharges from mills with modern bleaching technologies. Modifications in the bleaching plant to reduce molecular chlorine use are necessary to reduce dioxin formation. Received: 15 July 1998/Accepted: 17 March 1999  相似文献   
104.
In dentistry, acrylates have been used for preparing denture bases for 50 years. Although polymethylmethacrylates (PMMA) are known to be an ideal base material, they possess some undesirable mechanical properties, especially their impact strength and tensile strength, which appear to be unsatisfactory for some applications. Additives and fibers have therefore been used to enhance and improve these properties over the last two decades. The present article describes the mechanical properties, impact and tensile strength of PMMA reinforced with chopped ultra-high molecular weight polyethylene fiber (6 mm long). It was found that, although the processing involved for high loading of fibers into the PMMA was difficult, the resulting improvement of impact strength was substantial.  相似文献   
105.
目的:探讨L-精氨酸对病毒性心肌炎病理变化的影响。方法:将接种柯萨基病毒B3的Balb/c雄性小鼠随机分为饲服L-精氨酸组和对照组,于接种病毒后第5d测小鼠血清NO(NO2/NO3)和CK-MB,心肌组织病理学改变和超微结构变化。结果:血清NO(NO2/NO3)和血清CK-MB,L-精氨酸组高于对照组;心肌组织病理学检查可见L-精氨酸组小鼠心肌细胞有程度不等的空泡变性和坏死,病理损伤较对照组严重;  相似文献   
106.
目的:评价植入新型人工腰椎间盘的腰椎节段的稳定性和压缩力学性能。方法:将人工腰椎间盘植入6具新鲜青壮年尸体标本的L4-5椎间隙,进行三维运动范围和压缩刚度测试,并与植入前和髓核切除后进行比较。结果:新型人工腰椎间盘植入后,腰椎节段的三维运动范围为前屈146°,后伸66°,左侧弯79°,右侧弯89°,左轴向旋转85°,右轴向旋转87°。其压缩刚度比髓核切除后高(P<005)。结论:新型人工腰椎间盘植入后既保证了腰椎节段的三维运动功能,又起到了稳定脊柱的功能。  相似文献   
107.
STUDY AIM: The aim of this study was to report the immediate results of a series of 65 hepatic resections for hepatolithiasis performed in Vietnam. PATIENTS AND METHOD: From 1986 to 1998, 44 men and 21 women (mean age: 40 years) underwent hepatic resection for hepatolithiasis. Fourty patients had previously undergone one or several operations for hepatolithiasis. The procedure was performed on emergency in 25 patients. Indications for hepatic resection were: angiocholitis and liver abscess in 22 cases, stones closely inserted in the biliary duct in 20 cases, hemobilia in 12 cases, stones located above a biliary stricture in 8 cases and stones associated with a postoperative biliary fistula in 3 cases. Liver resections (minor in 61 patients, including 55 left lobectomies, and major in 4 patients) were performed through transhepatic approach according to the Ton That Tung technique and followed by an external biliary drainage with a Kehr tube. RESULTS: There were 6 postoperative deaths (9%), 3 due to septic shock, 2 to cachexia, and 1 to liver failure. The 15 patients with complications recovered with conservative therapy. Bile infection was present in 93%, mostly with Escherichia coli and Enterobacter. Pigmented stones were usually found. CONCLUSION: Vietnam is a country with high incidence of hepatolithlasis. Hepatic resection is an adequate treatment for localized intrahepatic bile duct stones when the involved segment including biliary strictures and calculi can be completely removed. The procedure may be performed on emergency for liver abscess, or hemobilia.  相似文献   
108.
Magnetic resonance imaging of pulmonary parenchyma perfusion using pulsed arterial spin labeling (ASL) techniques is presented. ASL uses magnetically labeled water as an endogenous, freely diffusible tracer. Presented are comparative results of ASL methods called Flow sensitive Alternating Inversion Recovery (FAIR), and FAIR with an Extra Radiofrequency pulse (FAIRER). Six healthy human volunteers were imaged. Perfusion-weighted images at different time delays, TI, were calculated from the subtraction of the control and tag images, which were acquired within a single breathhold. Detailed pulmonary structures can be visualized with negligible cardiac or respiratory motion artifacts. Different patterns of signal enhancement between the pulmonary vessels and parenchyma are shown in the perfusion images acquired at different TIs.  相似文献   
109.
 Cyclosporine is a powerful immunosuppressant with a narrow therapeutic window and considerable inter- and intrapatient variability. The pre-dose trough concentration (Cmin) is commonly used for therapeutic drug monitoring. With the new microemulsion (Neoral), intrapatient variability was reduced. However, the usefulness of Neoral Cmin was questioned. Firstly, because of the improved and more-rapid absorption, accidental intake before blood sampling has a greater impact on Cmin than with classic cyclosporine. Secondly, Cmin may be low despite high drug exposure, due to rapid clearance in children. A full pharmacokinetic (PK) profile with determination of the area under the curve (AUC) is expensive and cumbersome, and therefore a search for an abbreviated AUC began. Here, we present a retrospective analysis of 84 PK profiles from 78 pediatric renal transplant recipients. By analysis of rejection episodes and toxicity, we estimated a target AUC above 5,000 ng×h/ml in the early post-transplant period and 3,900 ng×h/ml beyond 100 days. The abbreviated AUC using the 2- and 6-h concentrations (C2 and C6) and a simple estimate derived from the 3-h concentration (C3) were equally well correlated with the AUC. From our data, we recommend a target C3 at approximately 800 ng/ml early after transplantation and 450–550 ng/ml beyond 100 days. Received: 28 January 1998 / Revised: 10 June 1998 / Accepted: 15 June 1998  相似文献   
110.
BACKGROUND: The association of posterior inferior cerebellar artery (PICA) aneurysms with posterior fossa arteriovenous malformation (AVM) is uncommon. Over the past 3 years, five patients with this condition were treated at this institution. A review of the clinical history of these and other reported cases has illuminated common threads in the presentation, treatment, and outcome of these lesions. METHODS: The findings of 27 patients (5 from our institution and 22 from the medical literature) with PICA aneurysms associated with AVMs were reviewed. RESULTS: Eighty-four percent of individuals presented with sub-arachnoid hemorrhage (SAH); 89% of these episodes resulted from aneurysm rupture documented by either intraoperative inspection or autopsy. All aneurysms were located on a feeding artery to the AVM, and 81% originated from distal portions of PICA. The majority of patients presented with Hunt & Hess grade I SAH; all patients who presented with hemorrhage were treated surgically. Surgical strategy was directed both to secure the aneurysm and to resect the AVM during the course of a single procedure. Although four individuals either died on admission or in the perioperative period, overall outcome was excellent or good in 82% of patients. CONCLUSIONS: PICA aneurysms associated with AVMs most often involve the distal segments of the artery. Patients usually present with SAH secondary to aneurysmal rupture. Surgical clipping of the aneurysm and excision of the AVM is possible in a single procedure with minimal morbidity. Overall prognosis is favorable in 80% of the cases.  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