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   15628篇
  免费   909篇
  国内免费   201篇
耳鼻咽喉   285篇
儿科学   409篇
妇产科学   362篇
基础医学   2231篇
口腔科学   445篇
临床医学   1386篇
内科学   3228篇
皮肤病学   325篇
神经病学   1128篇
特种医学   1029篇
外科学   1947篇
综合类   200篇
一般理论   1篇
预防医学   838篇
眼科学   449篇
药学   1257篇
  2篇
中国医学   169篇
肿瘤学   1047篇
  2023年   102篇
  2022年   252篇
  2021年   476篇
  2020年   216篇
  2019年   344篇
  2018年   462篇
  2017年   323篇
  2016年   413篇
  2015年   612篇
  2014年   687篇
  2013年   911篇
  2012年   1311篇
  2011年   1237篇
  2010年   757篇
  2009年   643篇
  2008年   847篇
  2007年   814篇
  2006年   763篇
  2005年   670篇
  2004年   576篇
  2003年   474篇
  2002年   434篇
  2001年   404篇
  2000年   348篇
  1999年   263篇
  1998年   213篇
  1997年   204篇
  1996年   168篇
  1995年   154篇
  1994年   155篇
  1993年   136篇
  1992年   142篇
  1991年   123篇
  1990年   120篇
  1989年   141篇
  1988年   117篇
  1987年   103篇
  1986年   100篇
  1985年   94篇
  1984年   55篇
  1983年   43篇
  1982年   44篇
  1981年   39篇
  1980年   38篇
  1979年   17篇
  1978年   24篇
  1977年   31篇
  1976年   36篇
  1975年   28篇
  1974年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
Patellofemoral joint: kinematic MR imaging to assess tracking abnormalities   总被引:4,自引:0,他引:4  
Shellock  FG; Mink  JH; Fox  JM 《Radiology》1988,168(2):551-553
The patellofemoral joint was imaged with magnetic resonance (MR) in the axial plane while the knee was positioned from 0 degrees to 32 degrees of flexion (nine positions). These multiple sequential images obtained within the early phases of flexion of the knee were viewed in a "cine-loop" format, producing a kinematic study that clearly demonstrated the relationship of the patella to the trochlear groove. Four healthy subjects and one patient with known bilateral subluxing patellae were studied. The preliminary results suggest that kinematic MR imaging of the patellofemoral joint is potentially useful for the evaluation of patellar tracking abnormalities.  相似文献   
64.
From November 1999 to December 2001, three outbreaks of adenovirus (Ad) respiratory infection occurred in southern Taiwan. To determine the circulating serotypes and molecular epidemiology, a total of 524 virus strains were randomly selected from 1,064 strains isolated from 1981 to 2001, and were studied using restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR)-RFLP. The major subgenus found was subgenus B (45%), followed by subgenus E (29%) and subgenus C (25%). Ad3 and Ad7 were the major types found during the 1st outbreak, which occurred from November 1999 to March 2000, while Ad4 was found mainly during the 2nd and 3rd outbreaks in October 2000 and September 2001, respectively. Both Ad7 and Ad4 were reemerged serotypes, whereas Ad3 was consistently isolated during the survey, although it declined drastically from 36 to 2% in 2001. Genotype analysis in this study showed that the only strain of Ad7 found in 1983 was Ad7a, but all randomly selected strains of Ad7 isolated during 1999-2000 were Ad7b. The clinical features of 217 patients were analyzed during the 1999-2000 outbreaks. About 79% of the total cases were less than 7 years old. The ratio of male to female was 2:1. Severe infections, such as pneumonia and acute bronchitis, accounted for nearly half of the cases (43%). These results show the reemergence and changing of serotypes, the clinical association of respiratory adenovirus infections, and the molecular epidemiology of Ad7 genotypes in Taiwan during the past two decades.  相似文献   
65.
Nitric oxide (NO) inhalation therapy has been employed in the management of acute respiratory distress syndrome (ARDS), in order to improve oxygenation. Several factors have been implicated as being responsible for the action of inhaled NO. Alveolar recruitment methods, such as prone positioning and a sufficient positive end expiratory pressure (PEEP), have been identified as having a positive impact on the NO response. A Recruitment maneuver (RM) was introduced for the treatment of ARDS, along with a lung protective strategy. Here, we hypothesized that a RM may further augment the oxygenation of patients treated with NO inhalation. Therefore, the effects of the inhalation of NO, either in combination with a RM, or separately, were evaluated on patients with ARDS for their enhancing action. 23 patients with ARDS were enrolled, and divided into three groups. The patients in group 1 (n=11) were treated with 5 ppm NO via inhalation, followed by a RM, applying a sustained inflation pressure of 30 - 35 cmH2O for 30 seconds. Group 2 (n=6) received a RM alone, while group 3 (n=3) was treated with NO inhalation alone. The oxygenation and hemodynamic parameters were obtained prior to, and 2, 12, and 24 h after, the respective treatment procedures. For group 1, the PaO2/FiO2 increased from its initial value of 171.8 +/- 67.8 to 203.2 +/- 90.0 2 h after NO inhalation. Further improvement was noted with the continual application of the RM reaching, 215.5 +/- 74.6 (p=0.05) and 254.2 +/- 109.5 (p < 0.05), after 12 and 24 h, respectively. Initially 7 of the subjects did not respond to NO inhalation, but 3 of these non-responders changed into responders 12 h after the RM. The changes in the PaO2/FiO2 from baseline at each time period were greater in group 1 than in the other groups, but with no statistical significance. The hemodynamics of the patients was not significantly altered during the entire study period. We conclude that the combined application of NO inhalation and a RM could be beneficial and safe for patients with ARDS, showing an enhancing effect in improvement of oxygenation.  相似文献   
66.
We report an instance of critical ovarian hyperstimulation syndrome in a highly responsive in-vitro fertilization patient despite the preventive measure of a 4 day 'coast' interval during which no gonadotrophins were administered while gonadotrophin-releasing hormone agonist therapy continued until serum oestradiol concentrations fell below 3000 pg/ml.   相似文献   
67.
BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a major health problem with an estimated prevalence of 10-15% among smokers. The incidence of moderate COPD, as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD), is largely unknown. AIM: To determine the cumulative incidence of moderate COPD (forced expiratory volume in 1 second/forced vital capacity ratio [FEV1/FVC] <0.7 and FEV1 <80% predicted) and its association with patient characteristics in a cohort of male smokers. DESIGN: Prospective cohort study. SETTING: The city of IJsselstein, a small town in the Netherlands. METHOD: Smokers aged 40-65 years who were registered with local GPs, participated in a study to identify undetected COPD. Baseline measurements were taken in 1998 of 399 smokers with normal spirometry (n = 292) or mild COPD (FEV1/FVC <0.7 and FEV1 >or=80% predicted, n = 107) and follow-up measurements were conducted in 2003. RESULTS: After a mean follow-up of 5.2 years, 33 participants developed moderate COPD (GOLD II). This showed an estimated cumulative incidence of 8.3% (95% CI = 5.8 to 11.4) and a mean annual incidence of 1.6%. No participant developed severe airflow obstruction. The risk of developing moderate COPD in smokers with baseline mild COPD (GOLD I) was five times higher than in those with baseline normal spirometry (one in five versus one in 25). CONCLUSIONS: In a cohort of middle-aged male smokers, the estimated cumulative incidence of moderate COPD (GOLD II) over 5 years was relatively high (8.3%). Age, childhood smoking, cough, and one or more GP contacts for lower respiratory tract problems were independently associated with incident moderate COPD.  相似文献   
68.
69.
OBJECTIVE: Oxidative stress such as free radical-mediated neuronal dysfunction may be involved in the pathophysiology of schizophrenia. The human glutathione peroxidase (GPX1) is a selenium-dependent enzyme, which plays an important role in the detoxification of free radicals. We therefore hypothesized that the GPX1 gene, which is located on chromosome 3p21.3, may be involved in the pathophysiology of schizophrenia. The aim of this study is to examine whether a potentially functional polymorphism, a proline (Pro) to leucine (Leu) substitution at codon 197 (Pro197Leu) of the human GPX1 gene, is associated with susceptibility to schizophrenia. METHODS: We genotyped the Pro197Leu polymorphism in a total of 113 nuclear families that had a proband with schizophrenia. Genetic association was tested using the transmission disequilibrium test (TDT), the sib transmission disequilibrium test (STDT), and the family-based association test (FBAT). RESULTS: The minor allele (Leu) frequency was calculated to be 0.282. We could not find significant transmission disequilibrium of the alleles for the Pro197Leu polymorphism in the GPX1 gene in association with the presence of schizophrenia in our family sample (TDT, chi2=0.03, degrees of freedom=1, P=0.86; combined TDT-STDT, Z'=-0.052, P=0.47; FBAT, Z=0.000, P=1.000). CONCLUSION: The results of this study suggest that the GPX1 polymorphism is unlikely to be associated with susceptibility to schizophrenia.  相似文献   
70.
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