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   14865篇
  免费   825篇
  国内免费   69篇
耳鼻咽喉   128篇
儿科学   289篇
妇产科学   462篇
基础医学   1797篇
口腔科学   514篇
临床医学   1207篇
内科学   4241篇
皮肤病学   373篇
神经病学   1334篇
特种医学   305篇
外科学   2168篇
综合类   95篇
一般理论   2篇
预防医学   1074篇
眼科学   211篇
药学   788篇
中国医学   69篇
肿瘤学   702篇
  2023年   139篇
  2022年   304篇
  2021年   626篇
  2020年   327篇
  2019年   511篇
  2018年   674篇
  2017年   392篇
  2016年   406篇
  2015年   459篇
  2014年   695篇
  2013年   813篇
  2012年   1277篇
  2011年   1291篇
  2010年   655篇
  2009年   586篇
  2008年   998篇
  2007年   918篇
  2006年   890篇
  2005年   862篇
  2004年   758篇
  2003年   597篇
  2002年   599篇
  2001年   67篇
  2000年   66篇
  1999年   80篇
  1998年   92篇
  1997年   63篇
  1996年   70篇
  1995年   59篇
  1994年   46篇
  1993年   33篇
  1992年   38篇
  1991年   25篇
  1990年   23篇
  1989年   19篇
  1988年   18篇
  1987年   11篇
  1986年   24篇
  1985年   19篇
  1984年   22篇
  1983年   17篇
  1982年   23篇
  1981年   20篇
  1980年   22篇
  1979年   8篇
  1978年   12篇
  1974年   11篇
  1973年   19篇
  1972年   10篇
  1971年   7篇
排序方式: 共有10000条查询结果,搜索用时 365 毫秒
991.
A retrospective study was conducted on 186 patients with differentiated thyroid cancer without metastases who received an ablative dose of 100 mCi (3.7 GBq) iodine-131 after total thyroidectomy. Six months to one year after ablation, 155/186 patients (83%) had a negative scan. Diagnostic scanning with 5 mCi (185 MBq) performed 72 h or 3 months before ablation did not interfere with treatment success compared to patients not submitted to pre-therapy scanning. Pre-ablation cervical uptake values < 2% were associated with a higher ablation efficacy (94%), from 2 to 5% showed 80% success and values > 5%, 60% (p < 0.05). There were no significant differences between the responsive and no responsive groups in terms of age, sex, histological type or size of the primary tumor. 11% of the patients with low stimulated Tg (< 2 ng/ml) presented discrete thyroid bed uptake on follow-up diagnostic scan (< 0.5%) without definitive residual disease and 89% had negative uptake on scan. The patients with Tg > 2 ng/ml presented thyroid bed (10/12) or ectopic (2/12) uptake on follow-up diagnostic scan. An ablative dose of 100 mCi shows a high rate of efficacy, especially when cervical uptake is < 2%; no difference was noted between patients assessed by scan within 72 h or 3 months before treatment and those not scanned; follow-up diagnostic scan can be avoided in low risk patients with stimulated Tg < 2 ng/ml.  相似文献   
992.
993.
994.
Ductoscopy-assisted microdochectomy   总被引:2,自引:0,他引:2  
Until 10 years ago, examination of the ductal system of the breast required excision of all the major ducts, in a block of tissue. With mammary ductoscopy, direct visualization of the ducts in vivo has been possible. In the present series of 40 cases, ductoscopy was used to guide the infusion of methylene blue dye, through the endoscope, to find the index duct, which is then removed through a small incision just inside the areola.  相似文献   
995.
BACKGROUND: The relevance of tooth mobility on periodontal healing is still controversial. The purpose of the present study was to evaluate the effect of presurgical tooth mobility on periodontal regenerative outcomes. METHODS: The data in this study were derived from three randomized clinical trials which evaluated regenerative procedures. Sixty-four patients with one intraosseous periodontal defect each received one of the following treatments: guided tissue regeneration (GTR) using expanded polytetrafluoroethylene (ePTFE), GTR using a bioabsorbable membrane with or without demineralized freeze-dried bone allograft (DFDBA), or enamel matrix derivative with or without DFDBA. Probing depth (PD), clinical attachment level (CAL), recession (REC), and tooth mobility (TM) were recorded at baseline and 1 year after treatment by a calibrated examiner. The post-surgical follow-up and maintenance periods were designed to optimize plaque control. The teeth were grouped according to their baseline Miller index TM score. The grouping yielded 36 teeth with minimal mobility, score 0; 13 teeth with score 1; and 15 with score 2. The mean changes in PD, CAL and REC from baseline to 1 year were calculated for each group. One-way analysis of variance (ANOVA) was performed to assess differences between the tooth mobility groups considering changes in PD, CAL, and REC at 1 year. RESULTS: The mean PD reduction from baseline to 1 year for teeth with TM score 0 was 3.67 mm; for TM score 1, 2.81 mm; and for score 2, 3.73 mm. The corresponding values for the gain in CAL were 2.73, 1.96, and 2.36 mm, respectively. According to ANOVA, the probing depth reductions and clinical attachment level gains found in each group were not statistically different, P= 0.218 and P= 0.252, respectively. CONCLUSION: Within the limitations of this analysis, it can be concluded that interproximal, intraosseous defects of teeth with limited presurgical tooth mobility; i.e., teeth with Miller's Class 1 and 2 mobility, will respond favorably to regenerative therapy.  相似文献   
996.
Dens invaginatus is an anomaly that has numerous complex forms. Whenever endodontic therapy involving such a tooth becomes necessary, the clinician must be aware of the various treatments available for proper care. We present a case report of a maxillary lateral incisor having the anomaly in which both nonsurgical and surgical treatment was performed.  相似文献   
997.
The subject of this paper was to conduct an in vitro study of the coronal leakage after root canal filling and post space preparation. One hundred single-rooted human teeth had their crowns removed and the canals prepared and filled by the lateral condensation technique with gutta-percha points and the sealers CRCS and Endofill (a Grossman cement). After post space preparation, the remainder of the filling was protected or not with 1mm of a plug of the following materials: Coltosol, Super Bonder (cyanoacrylate-ester), CRCS and Endofill. After 24 hours in saline, the specimens were immersed in a 2% methylene blue solution in a vacuum environment for 24 hours. The teeth were then sectioned longitudinally, leakage was evaluated linearly and the obtained data were submitted to the Kruskal-Wallis test. The results with the two sealers studied were similar between themselves and worse (p<0.01) than the groups with a protector plug. The statistical analysis ordered the experimental groups from the best to the worst in the following way: a - Endofill-Super Bonder, CRCS-Super Bonder, CRCS-CRCS; b - Endofill-Endofill; c - Endofill-Coltosol, CRCS-Coltosol; d - Endofill, CRCS.  相似文献   
998.
Mother-to-Infant transmission of hepatitis C virus (HCV) in Brazil   总被引:2,自引:0,他引:2  
Sixty-one women with anti-HCV antibodies, detected by a third-generation enzyme immunoassay (EIA3), were prospectively recruited for investigation of vertical HCV transmission during child-birth, at the University Hospital of the Catholic University of Campinas, Brazil, between January 1994 and July 1998. Six of the women presented coinfection with the human immunodeficiency virus type 1 (HIV-1). All of the 72 children born in this period were followed at least until they were 18 months of age. Analyses of anti-HCV, HCV RNA, and alanine aminotransferase were performed in a minimum of two blood samples during follow-up. One (2.4 per cent; 95 per cent CI, 2.2-7) of the 42 children born to HCV viremic mothers was both anti-HCV and HCV RNA-positive, with altered ALT levels. Passively transferred maternal anti-HCV antibodies became undetectable within 9-12 months. None of the nine infants born to HIV-1 infected mothers were infected either by HIV or HCV. Thus, the mother-infant HCV transmission rate is low and seems to be associated with maternal HCV RNA positivity.  相似文献   
999.
BACKGROUND: The efficacy of the intranasal, live-attenuated, trivalent cold-adapted influenza virus vaccine (CAIV-T) against influenza A(H3N2) and B infections in healthy persons is established, but its effectiveness against natural influenza A(H1N1) infection is unknown. OBJECTIVE: To assess the effectiveness of CAIV-T in healthy children during the 2000-2001 influenza A(H1N1) and B epidemic. DESIGN: Community-based, nonrandomized, open-label trial from August 1998 through April 2001. SETTING: Intervention and comparison communities in central Texas. PARTICIPANTS: Healthy children, aged 1.5 to 18 years, from the intervention communities received a single dose of CAIV-T at least 1 time or more in 1998, 1999, and/or 2000. MAIN OUTCOME MEASURES: The incidence of medically attended acute respiratory illnesses during the 2000-2001 influenza epidemic was compared in 3794 health plan CAIV-T recipients with age-eligible, health plan nonrecipients in the intervention communities for direct effectiveness (n = 9325), and with those in the 2 comparison communities for total effectiveness (n = 16,264). RESULTS: The 2281 CAIV-T recipients in 2000 had significant direct protection against medically attended acute respiratory illness of 18% to 20% during the biphasic influenza A(H1N1) and B epidemic, and 17% to 26% during influenza A(H1N1) predominance. The 931 recipients of CAIV-T in 1999 containing influenza A/Beijing/262/95(H1N1) and B/Beijing/184/93-like viruses had persistent heterovariant protection against the 2000-2001 influenza A/New Caledonia/20/99(H1N1) and B/Sichuan/379/99 variants. The 616 recipients of a single CAIV-T dose in 1999 only, including those younger than 5 years with no prior natural exposure to influenza A(H1N1) viruses, showed persistent protection. CONCLUSION: Healthy children who received CAIV-T in 2000 or 1999 were protected against new variants of influenza A(H1N1) and B in the 2000-2001 influenza epidemic.  相似文献   
1000.
Spinal epidural abscess due to Streptococcus pneumoniae is extremely rare in adults. It typically occurs in the thoracic, lumbar or lumbosacral epidural spaces, and less frequently in the cervical epidural space. The principal causative microbial agent is Staphylococcus aureus, representing 70% of cases, while 1.6% of cases are caused by S. pneumoniae. We report the first case of an HIV-infected patient with a cervical spinal epidural abscess. The patient was a 43-year-old male with pneumococcal bacteremia and a metatarsal abscess. He reported cervical pain with muscle spasm during cephalic flexion and extension, fever and a painful tumefaction on the second metatarsal of the left foot. MRI confirmed that the retropharyngeal abscess extended to the cervical spinal epidural space. Antibiotic therapy with cefotaxime plus vancomycin was initiated and a transoral surgical approach was used to achieve retropharyngeal and local debridement of the metatarsal abscess. Blood and pus cultures were positive for S. pneumoniae. After 4 months of follow-up the patient remained asymptomatic, without clinical or MRI evidence of recurrence.  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