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   1505篇
  免费   65篇
  国内免费   9篇
耳鼻咽喉   7篇
儿科学   111篇
妇产科学   24篇
基础医学   132篇
口腔科学   32篇
临床医学   97篇
内科学   251篇
皮肤病学   17篇
神经病学   85篇
特种医学   106篇
外科学   352篇
综合类   10篇
一般理论   2篇
预防医学   69篇
眼科学   46篇
药学   146篇
中国医学   9篇
肿瘤学   83篇
  2024年   2篇
  2023年   9篇
  2022年   11篇
  2021年   66篇
  2020年   22篇
  2019年   48篇
  2018年   55篇
  2017年   29篇
  2016年   32篇
  2015年   56篇
  2014年   65篇
  2013年   89篇
  2012年   138篇
  2011年   140篇
  2010年   76篇
  2009年   75篇
  2008年   102篇
  2007年   111篇
  2006年   93篇
  2005年   85篇
  2004年   74篇
  2003年   46篇
  2002年   44篇
  2001年   9篇
  2000年   8篇
  1999年   9篇
  1998年   12篇
  1997年   3篇
  1996年   6篇
  1995年   9篇
  1994年   3篇
  1993年   4篇
  1992年   3篇
  1991年   8篇
  1990年   3篇
  1989年   2篇
  1987年   5篇
  1986年   2篇
  1985年   2篇
  1983年   4篇
  1982年   4篇
  1981年   1篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1973年   1篇
  1971年   2篇
  1970年   1篇
  1968年   3篇
  1954年   1篇
排序方式: 共有1579条查询结果,搜索用时 583 毫秒
21.
22.
23.
Estimation of spatial plant distribution of a large area is very tedious and time consuming assignment. In this regard, herbaria of the world are supposed to be the excellent repositories of the plant collections for reference purpose. But many repositories of the world do not have the associated information of the collections and thus it becomes a muddle for future studies. The aim of this study is to know the extent of this mess. Therefore, spatial distribution of Berberidaceae members in NW Himalaya was studied through available herbarium data in three herbaria at Department of Botany, University of Jammu, Janaki Ammal Herbarium, Indian Institute of Integrative Medicine and Herbarium, Department of Botany, Punjabi University. It is observed that the collected specimens in aforesaid herbaria are correctly identified; but simultaneously, proper collection sites and collection dates are not mentioned for some specimens. Therefore, it is difficult to recollect the species. This is also revealed that India harbours 04 genera (Berberis, Epimedium, Mahonia and Nandina) and 22 species of the Berberidaceae, out of which 02 (Berberis and Mahonia) are reported from the NW Himalaya.  相似文献   
24.
25.
Physician accuracy in diagnosing colorectal polyps   总被引:3,自引:4,他引:3  
Since the medical management of persons with adenomatous colorectal polyps differs from that of those with hyperplastic polyps, accuracy of diagnosis is essential. Although many physicians have grown confident that their skills of visual diagnosis are adequate, few data exist to support this confidence. In order to examine the accuracy of physicians' judgments regarding colorectal polyp histology, the visual diagnosis of physicians experienced in endoscopy was compared with the histologic report. Eighty-one polyps were discovered by flexible sigmoidoscopy among 718 participants in a colon cancer screening program. Eighty percent of all polyps were detected accurately. The diagnostic sensitivity of detecting adenomas was 69 percent, while specificity (accurate diagnosis of hyperplastic polyps) was 86 percent, and there were an additional eight false negative and eight false positive diagnoses. Further analyses revealed that there are individual patterns of diagnostic mistakes made by physicians and that mistakes frequently are related to polyp size. These findings are particularly important in light of the expanding numbers of relatively inexperienced primary care providers performing flexible sigmoidoscopy whose diagnoses may be strongly dependent on polyp size. This research was done through, and supported by, the Center for Occupational Health, Department of Family Medicine, Wayne State University, Detroit, Michigan.  相似文献   
26.
BACKGROUND Nonalcoholic fatty liver disease(NAFLD)and type-2 diabetes mellitus(T2DM)have an intricate bidirectional relationship.Individuals with T2DM,not only have a higher prevalence of non-alcoholic steatosis,but also carry a higher risk of progression to nonalcoholic steatohepatitis.Experts still differ in their recommendations of screening for NAFLD among patients with T2DM.AIM To study the prevalence of NAFLD and advanced fibrosis among our patient population with T2DM.METHODS During the study period(November 2018 to January 2020),59 adult patients with T2DM and 26 non-diabetic control group individuals were recruited prospectively.Patients with known significant liver disease and alcohol use were excluded.Demographic data and lab parameters were recorded.Liver elastography was performed in all patients.RESULTS In the study group comprised of patients with T2DM and normal alanine aminotransferase levels(mean 17.8±7 U/L),81%had hepatic steatosis as diagnosed by elastography.Advanced hepatic fibrosis(stage F3 or F4)was present in 12%of patients with T2DM as compared to none in the control group.Patients with T2DM also had higher number of individuals with grade 3 steatosis[45.8%vs 11.5%,(P<0.00001)and metabolic syndrome(84.7%vs 11.5%,P<0.00001)].CONCLUSION A significant number of patients with T2DM,despite having normal transaminase levels,have NAFLD,grade 3 steatosis and advanced hepatic fibrosis as measured by liver elastography.  相似文献   
27.
We sought to determine whether diabetes mellitus independently conferred poor prognosis in patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI). In 3,742 patients enrolled in the Primary Angioplasty in Myocardial Infarction (PAMI) studies with the intention of undergoing primary PCI, we compared in-hospital mortality, 6-month mortality, and 6-month major adverse cardiovascular events (MACEs), i.e., composite of death, reinfarction, or ischemic target vessel revascularization (TVR), between diabetics (n = 626, 17%) and nondiabetics (n = 3,116, 83%). We evaluated the independent impact of diabetes on outcomes after adjustment for baseline clinical and angiographic differences. Diabetics had worse baseline clinical characteristics, longer pain onset-to-hospital arrival time, and longer door-to-balloon time. They had more multivessel coronary disease and lower left ventricular ejection fractions, but better baseline Thrombolysis In Myocardial Infarction (TIMI) flow. Diabetics underwent primary PCI less often (88% vs 91%, p = 0.01). During the index hospitalization, diabetics were more likely to die (4.6% vs 2.6%, p = 0.005). During 6-month follow-up, diabetics had higher incidences of death (8.1% vs 4.2%, p <0.0001) and MACEs (18% vs 14%, p = 0.036). In multivariate analysis, diabetes was independently associated with 6-month mortality (hazard ratio 1.53, 95% confidence interval 1.03 to 2.26, p = 0.03), but not with in-hospital mortality or 6-month MACEs. We conclude that diabetics with AMI have less favorable baseline characteristics and are less likely to undergo primary PCI than nondiabetics. Despite excellent angiographic results, diabetics had significantly worse 6-month mortality.  相似文献   
28.
29.
30.
HIV‐1 infection and progression exhibits interindividual variation. The polymorphism in the chemokine receptors CCR5 and CXCR4, the principal coreceptors for HIV‐1 and their ligands like SDF‐1 have a profound effect in altering the HIV‐1 disease progression rate. A single nucleotide polymorphism designated SDF1‐3′UTR‐801G‐A has been associated with resistance to HIV‐1 infection or delayed progression to AIDS. In this study, the SDF1‐3′A polymorphism, CCR5?32 polymorphism and CCR5 promoter polymorphism at positions 58934 G/T, 59029 G/A, 59353 T/C, 59356 C/T, 59402 A/G and 59653 C/T were analysed in Indian population. The polymorphisms in HIV‐1 patients and healthy individuals were evaluated by conventional PCR, RFLP‐PCR and direct sequencing techniques. The CCR5?32 mutant allele was found to be almost absent in Indian population. The analysis of the CCR5‐59356C/T polymorphism revealed a trend towards an association of the C allele with an increased risk of HIV‐1 infection. The frequency of allele CCR5‐59356C was higher in HIV‐1 patients (100%) as compared to healthy control subjects (89%, = 0.003). The correlation of SDF1‐3′A and CCR5 promoter CCR5‐58934G/T, CCR5‐59029G/A, CCR5‐59353T/C, CCR5‐59402 A/G and CCR5‐59653C/T polymorphisms and protection to HIV‐1 infection and progression to AIDS was found to be nonsignificant. Nine haplotypes with more than 1% frequency were detected but were not significant in their protective role against HIV. Comparative analysis with global populations showed a noteworthy difference in CCR5 and SDF‐1 polymorphisms’ frequency distribution, indicating the ethnic variability of Indians. Although susceptibility to infections cannot be completely dependent on one or few genetic variants, it is important to remember that SDF‐1 and CCR5 variants have been correlated globally with HIV‐1 infection and disease progression. In the light of that, higher frequency of SDF‐1 variants in the Indian population is noteworthy.  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