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   4870篇
  免费   355篇
  国内免费   23篇
耳鼻咽喉   58篇
儿科学   180篇
妇产科学   78篇
基础医学   705篇
口腔科学   230篇
临床医学   498篇
内科学   1016篇
皮肤病学   147篇
神经病学   489篇
特种医学   171篇
外科学   504篇
综合类   36篇
一般理论   1篇
预防医学   346篇
眼科学   42篇
药学   391篇
中国医学   1篇
肿瘤学   355篇
  2023年   24篇
  2021年   65篇
  2020年   55篇
  2019年   59篇
  2018年   79篇
  2017年   61篇
  2016年   84篇
  2015年   67篇
  2014年   101篇
  2013年   165篇
  2012年   212篇
  2011年   203篇
  2010年   123篇
  2009年   140篇
  2008年   223篇
  2007年   204篇
  2006年   238篇
  2005年   218篇
  2004年   213篇
  2003年   192篇
  2002年   180篇
  2001年   167篇
  2000年   142篇
  1999年   137篇
  1998年   82篇
  1997年   76篇
  1996年   76篇
  1995年   61篇
  1994年   57篇
  1993年   65篇
  1992年   137篇
  1991年   119篇
  1990年   102篇
  1989年   123篇
  1988年   82篇
  1987年   100篇
  1986年   92篇
  1985年   103篇
  1984年   71篇
  1983年   59篇
  1982年   44篇
  1981年   35篇
  1980年   30篇
  1979年   33篇
  1978年   39篇
  1977年   32篇
  1976年   23篇
  1975年   27篇
  1974年   33篇
  1972年   27篇
排序方式: 共有5248条查询结果,搜索用时 15 毫秒
91.
AIM: To evaluate cut-off values and performance of acoustic radiation force impulse imaging (ARFI) using transient elastography [FibroScan© (FS)] as a reference.METHODS: Six hundred and six patients were enrolled in this study. All patients underwent liver stiffness measurement with FS (FS-LS) and ARFI (with shear wave velocity quantification; ARFI-SWV) and the performance of ARFI in comparison to FS was determined. Sixty-eight patients underwent liver biopsy.RESULTS: Significantly higher success rates for the determination of liver stiffness were found using ARFI as compared to FS [604/606 (99.7%) vs 482/606 (79.5%), P < 0.001]. ARFI-SWV correlated significantly with FS-LS (r = 0.920, P < 0.001). ARFI-SWV increased significantly with the stage of fibrosis (1.09 ± 0.13 m/s for patients with no significant fibrosis (FS-LS < 7.6 kPa); 1.46 ± 0.27 m/s for patients with significant liver fibrosis (7.6 < FS-LS ≤ 13.0 kPa); and 2.55 ± 0.77 m/s for patients with liver cirrhosis (FS-LS > 13.0 kPa)). ARFI-SWV cut-off values were identified for no significant fibrosis (1.29 m/s; sensitivity 91.4% and specificity 92.6%) and for liver cirrhosis (1.60 m/s; sensitivity 92.3% and specificity 96.5%). The optimal cut-off value for predicting liver fibrosis (F ≥ 2) was 1.32 m/s (sensitivity 87.0% and specificity 80.0%) and for liver cirrhosis (F4) 1.62 m/s (sensitivity 100% and specificity 85.7%), for patients who underwent liver biopsy. An excellent inter-and intraobserver reproducibility was observed for ARFI-SWV determinations.CONCLUSION: An ARFI-SWV cut-off value of 1.29 m/s seems to be optimal for patients with no significant liver fibrosis and 1.60 m/s for patients with liver cirrhosis.  相似文献   
92.
93.
94.

Background

Preprocedure clinical and pathologic factors have failed to consistently differentiate complete response (CR) from progressive disease (PD) in patients after isolated limb infusion (ILI) with melphalan for unresectable in-transit extremity melanoma.

Methods

Multiplex immunobead assay technology (Milliplex MAP Human Cytokine/Chemokine Magnetic Bead Panel, Millipore Corp., Billerica, MA; and Magpix analytical test instrument, Luminex Corp., Austin, TX) was performed on pre-ILI plasma to determine concentrations of selected cytokines (MIP-1α, IL-1Rα, IP-10, IL-1β, IL-1α, MCP-1, IL-6, IL-17, EGF, IL-12p40, VEGF, GM-CSF, and MIP-1β) on a subset of patients (n = 180) who experienced CR (n = 23) or PD (n = 24) after ILI. Plasma from normal donors (n = 12) was also evaluated.

Results

Of 180 ILIs performed, 28 % (95 % confidence interval 22–35, n = 50) experienced a CR, 14 % (n = 25) experienced a partial response, 11 % (n = 21) had stable disease, 34 % (n = 61) had PD, and 13 % (n = 23) were not evaluable for response. Tumor characteristics and pharmacokinetics appeared similar between CR (n = 23) and PD (n = 24) patients who underwent cytokine analysis. Although there were no differences in cytokine levels between CR and PD patients, there were differences between the melanoma patients and controls. MIP-1α, IL-1Rα, IL-1β, IL-1α, IL-17, EGF, IL-12p40, VEGF, GM-CSF, and MIP-1β were significantly higher in normal controls compared to melanoma patients, while IP-10 was lower (p < 0.001) in controls compared to melanoma patients.

Conclusions

Patients with unresectable in-transit melanoma appear to have markedly decreased levels of immune activating cytokines compared to normal healthy controls. This further supports a potential role for immune-targeted therapies and immune monitoring in patients with regionally advanced melanoma.  相似文献   
95.
The aim of this study was to investigate the effectiveness of tablets containing two probiotic Lactobacillus reuteri strains in inhibiting regrowth of salivary mutans streptococci (MS) after full-mouth disinfection (FMD) with chlorhexidine. The null hypothesis was that the levels of MS would not differ in comparison with a placebo protocol. The study population was comprised of 62 young adults (mean age 23 years) with moderate or high counts of salivary MS who volunteered after informed consent. The study was a double-blinded randomized controlled trial with two parallel groups. After a 3-day chlorhexidine regimen, the subjects were randomly assigned to a test group (n = 32) with probiotic lozenges (2/day) or a placebo group (n = 30). The intervention period was 6 weeks, and stimulated whole saliva was collected at baseline and after 1, 6, and 12 weeks. The samples were processed for MS by a chair-side test and DNA-DNA hybridization as an estimate of 19 bacterial strains associated with oral health and disease. There was no significant difference between the groups at inclusion, and FMD reduced the salivary MS levels significantly in both groups. The MS suppression lasted less than 6 weeks and there were no statistical differences in salivary MS regrowth between the test and control groups at any of the follow-ups. Likewise, there were no major differences in the regrowth patterns of the checkerboard panel between the two groups. We conclude that daily oral administration of L. reuteri did not seem to affect or delay the regrowth of salivary MS after FMD with chlorhexidine.  相似文献   
96.
Dahlén G, Charalampakis G, Abrahamsson I, Bengtsson L, Falsen E. Predominant bacterial species in subgingival plaque in dogs. J Periodont Res 2012; 47: 354–364. © 2011 John Wiley & Sons A/S Background and Objective: The dog has been used extensively for experimental and microbiological studies on periodontitis and peri‐implantitis without detailed knowledge about the predominant flora of the subgingival plaque. This study was designed to evaluate the predominant cultivable bacterial species in dogs and compare them phenotypically and genotypically with corresponding human species. Material and Methods: Four subgingival samples were taken from two upper premolars in each of six Labrador retrievers. The samples from each dog were processed for anaerobic culture. From the samples of each dog, the five or six predominating bacteria based on colony morphology were selected and pure cultured. Each of the strains was characterized by Gram stain, anaerobic/aerobic growth and API‐ZYM test. Eighteen strains showing clear‐cut phenotypic differences were further classified based on DNA sequencing technology. Cross‐reactions of DNA probes from human and dog strains were also tested against a panel of both human and dog bacterial species. Results: Thirty‐one strains in the dogs were isolated and characterized. They represented 21 different species, of which six belonged to the genus Porphyromonas. No species was found consistently in the predominant flora of all six dogs. Porphyromonas crevioricanis and Fusobacterium canifelinum were the two most prevalent species in predominant flora in dogs. DNA probes from human and dog species cross‐reacted to some extent with related strains from humans and dogs; however, distinct exceptions were found. Conclusion: The predominant cultural subgingival flora in dogs shows great similarities with the subgingival bacteria from humans at the genus level, but distinct differences at the species level; however, a genetic relatedness could be disclosed for most strains investigated.  相似文献   
97.
The use of psychotropic drugs in the university hospitals in Tartu, Estonia; Huddinge, Sweden; and Badajoz, Spain, were studied, using the defined daily doses per 100 bed-days (DDD/100 bed-days) method. The total amount of drugs used in the surgical and medical departments was 50 DDD/100 bed-days in Huddinge, versus 33 and 14 DDD/100 bed-days in Tartu and Badajoz, respectively. Barbiturates accounted for 35% of all psychotropics in Tartu but were practically not used in Huddinge. In contrast, antidepressants were practically not used in Tartu. The use of psychotropic drugs in the intensive care units was highest in Huddinge (320 DDD/100 bed-days), compared with Tartu and Badajoz (177 and 96 DDD/100 bed-days, respectively). The frequency of psychotropic drug use were strikingly different in the three hospitals studied.  相似文献   
98.
Journal of Neurology - The aim of this work was to determine whether wearable inertial measurement units (IMUs) could detect gait improvements across different disability groups of people with...  相似文献   
99.
Osteogenesis imperfecta (OI) is a hereditary connective tissue disease that causes frequent fractures. Little is known about causes of death and length of survival in OI. The objective of this work was to calculate the risk and cause of death, and the median survival time in patients with OI. This study was a Danish nationwide, population‐based and register‐based cohort study. We used National Patient Register data from 1977 until 2013 with complete long‐term follow‐up. Participants comprised all patients registered with the diagnosis of OI from 1977 until 2013, and a reference population matched five to one to the OI cohort. We calculated hazard ratios for all‐cause mortality and subhazard ratios for cause‐specific mortality in a comparison of the OI cohort and the reference population. We also calculated all‐cause mortality hazard ratios for males, females, and age groups (0 to 17.99 years, 18.00 to 34.99 years, 35.00 to 54.99 years, 55.00 to 74.99 years, and >75 years). We identified 687 cases of OI (379 women) and included 3435 reference persons (1895 women). A total of 112 patients with OI and 257 persons in the reference population died during the observation period. The all‐cause mortality hazard ratio between the OI cohort and the reference population was 2.90. The median survival time for males with OI was 72.4 years, compared to 81.9 in the reference population. The median survival time for females with OI was 77.4 years, compared to 84.5 years in the reference population. Patients with OI had a higher risk of death from respiratory diseases, gastrointestinal diseases, and trauma. We were limited by the lack of clinical information about phenotype and genotype of the included patients. Patients with OI had a higher mortality rate throughout their life compared to the general population. © 2016 American Society for Bone and Mineral Research.  相似文献   
100.
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