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   383034篇
  免费   24504篇
  国内免费   2818篇
耳鼻咽喉   5200篇
儿科学   8301篇
妇产科学   10125篇
基础医学   53662篇
口腔科学   11911篇
临床医学   30338篇
内科学   79191篇
皮肤病学   8592篇
神经病学   27637篇
特种医学   14120篇
外国民族医学   82篇
外科学   61441篇
综合类   9973篇
现状与发展   1篇
一般理论   64篇
预防医学   17550篇
眼科学   9510篇
药学   31177篇
  7篇
中国医学   2214篇
肿瘤学   29260篇
  2021年   2767篇
  2019年   2801篇
  2018年   4606篇
  2017年   3490篇
  2016年   3600篇
  2015年   4131篇
  2014年   5831篇
  2013年   7511篇
  2012年   10208篇
  2011年   10394篇
  2010年   6300篇
  2009年   5936篇
  2008年   9618篇
  2007年   10472篇
  2006年   10400篇
  2005年   9449篇
  2004年   8992篇
  2003年   8696篇
  2002年   8389篇
  2001年   28303篇
  2000年   28849篇
  1999年   23725篇
  1998年   5222篇
  1997年   4287篇
  1996年   3893篇
  1995年   3521篇
  1994年   3149篇
  1993年   2859篇
  1992年   16099篇
  1991年   14859篇
  1990年   14205篇
  1989年   14006篇
  1988年   12621篇
  1987年   12087篇
  1986年   11134篇
  1985年   10349篇
  1984年   6939篇
  1983年   5635篇
  1982年   2729篇
  1979年   5507篇
  1978年   3359篇
  1977年   2992篇
  1975年   2655篇
  1974年   3091篇
  1973年   2884篇
  1972年   2846篇
  1971年   2788篇
  1970年   2523篇
  1969年   2551篇
  1968年   2266篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Introduction: Effective resuscitation with human albumin solutions is achieved with less fluid than with crystalloid solutions. However, the role of albumin in today’s critical care unit is also linked to its multiple pharmacological effects.

Areas covered: The potential clinical benefits of albumin in select populations of critically ill patients like sepsis seem related to immunomodulatory and anti-inflammatory effects, antibiotic transportation and endothelial stabilization. Albumin transports many drugs used in critically ill patients. Such binding to albumin is frequently lessened in critically ill patients with hypoalbuminemia. These changes could result in sub-optimal treatment. Albumin has immunomodulatory capacity by binding several bacterial products. Albumin also influences vascular integrity, contributing to the maintenance of the normal capillary permeability. Moreover, the albumin molecule encompasses several antioxidant properties, thereby significantly reducing re-oxygenation injury, which is especially important in sepsis. In fact, most studies of albumin administration are a combination of a degree of resuscitation with a degree of maintenance or supplementation of albumin.

Expert commentary: The potential clinical benefits of the use of albumin in selected critically ill patients such as sepsis seem related to its immunomodulatory and anti-inflammatory effects, antioxidant properties, antibiotic transportation and endothelial stabilization. Additional studies are warranted to further elucidate the underlying physiologic and molecular rationale.  相似文献   

52.
53.
A green extraction method, based on the use of 1,8-cineole (eucalyptol) as biosolvent, has been developed to prepare crude extracts from the brown alga Zonaria tournefortii characterized by chemical composition, particularly dominated by phenolic compounds derived from phloroglucinol. The main advantage of the developed technique are the recovery of eucalyptol, based on multistep liquid-liquid extraction with distilled water, followed by centrifugation and elimination of the aqueous phase, and the complete recycling of biosolvent by steam distillation. A comparative study between the proposed green extract and the conventional extract, prepared by solvent maceration using the mixture CH2Cl2/MeOH (1/1:v/v), was performed in terms of qualitative and quantitative determination of several parameters as:(i) the total phenolic content determined by the Folin-Ciocalteu assay, (ii) the presence of phenols determined by high performance liquid chromatography (HPLC), and (iii) the antioxidant activity assessed by the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay. In short, eucalyptol provides a safe and selective extraction of phenolic compounds from Zonaria tournefortii with no environmental side effects and a good recovery of the solvent.  相似文献   
54.

Background

Venous thromboembolism (VTE) is common in cancer patients and its treatment is associated with a high risk of recurrent VTE (rVTE) and bleeding.

Objectives

To analyze data from the Comparison of Acute Treatments in Cancer Hemostasis (CATCH) trial to describe the impact of rVTE and bleeding events on health-related quality of life.

Methods

The three-level EuroQol five-dimensional questionnaire (EQ-5D) data were collected monthly for up to 7 months in patients starting anticoagulation for newly diagnosed VTE. Analyses were designed to describe the impact of rVTE and bleeding on EQ-5D scores while controlling for effects of covariates such as background and clinical variables and longitudinal changes. A repeated-measures model with specification of the variance-covariance matrix to characterize the intrapatient correlation was used to estimate the utility values. The impact of an rVTE or a bleeding event was assumed to be reflected in the utility value when it occurred within 2 weeks from a planned data collection point.

Results

Data were available from 883 patients. A total of 76 rVTE and 159 bleeding events occurred during follow-up. rVTE had a significant impact on EQ-5D scores, with a decrement of ?0.075 on the basis of our reference case (male, no metastasis, Eastern Cooperative Oncology Group score = 1, Western European), but different patients might have different decrements. Bleeding events had a smaller (nonstatistically significant) impact on EQ-5D scores.

Conclusions

This data set study has quantified the decline in EQ-5D scores associated with experiencing rVTE or bleeding events in cancer patients. These results indicate the net gain in quality of life and impact on cost-effectiveness of secondary VTE prevention.  相似文献   
55.
56.

Objectives

We aimed to evaluate the relationship between baseline renal function and changes in telomere length in Han Chinese.

Methods

The telomere restriction fragment (TRF) length of leukocytes in the peripheral blood was measured in healthy volunteers recruited in 2014. The estimated glomerular filtration rate (eGFR) was calculated based on serum creatinine (Scr) and serum cystatin C (CysC)-eGFRcys and eGFRScr-cys through the Cockcroft-Gault formula (eGFRC-G) or the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI / eGFRCKD-EPI) equation. The correlation between telomere length changes over time and renal function was analyzed.

Results

Leukocyte TRF lengths were negatively correlated to age (r = -0.393, p < 0.001) and serum CysC (r = -0.180, p < 0.01), while positively associated with eGFRCKD-EPI, eGFRC-G, eGFRcys, and eGFRScr-cys (r = 0.182, 0.122, 0.290, and 0.254 respectively, p < 0.01). The 3-year change of telomere length was 46 bp/years. When adjusted for age, the associations between telomere length changes and baseline, subsequent TRF lengths, and serum CysC were no longer present. No association was observed between TRF length changes and renal function.

Conclusion

The rate of telomere length changes was affected by age and baseline telomere length. The telomere length changes might be important markers for aging.
  相似文献   
57.
58.
59.
The relationship between volatile fatty acids (VFAs) in pus and infecting bacterial species was examined in order to establish a rapid identification system for anaerobic microorganisms in purulent inflammation in the oro-maxillary region. VFAs were detected by the direct injection of pus into gas-liquid chromatography (GLC). Bacterial examination was carried out by anaerobic culture using blood agar plates. The bacterial identification was carried out mainly according to the VPI manual. Analysis of the direct VFA patterns of each sample resulted in 5 groups. The following bacterial species were the main isolates in each group: Streptococcus intermedius in Group A, Peptostreptococcus micros in Group B, Fusobacterium nucleatum in Group C, Bacteroides gingivalis in Group D, and Peptostreptococcus anaerobius in Group E. The profile of VFAs produced in the PYG culture medium of the above isolated bacteria was compared with the direct VFA patterns. Agreement ratios between direct and PYG VFA patterns were as follows: Group A, 47.1%; Groups B and C, 45.0%; Group D, 87.5%; and Group E, 62.9%. The acetic acid concentration was more than 14 x 10(-4) meq/ml in Group B, the butyric acid concentration was more than 7 x 10(-4) meq/ml in Group C, and the iso-caproic acid concentration was more than 14 x 10(-4) meq/ml in Group E. In these cases, it was found that the agreement ratios between the direct and PYG FVA pattern were high. In Group D, irrespective of the concentration of iso-valeric acid detected, the agreement ratio was very high. The antibiotic susceptibility of the isolates was studied. Efficiency rates of ABPC, PIPC, CCL, CEZ, CMZ, SBT/CPZ, JM, CLDM, MINO and GM were relatively low and resistant rates were high for the gram-negative rods.  相似文献   
60.
Angiolipoma of the tongue: report of a case   总被引:1,自引:0,他引:1  
Angiolipoma is a rare variety of lipoma in the maxillofacial region. Only eight cases have been documented so far. A case in which an angiolipoma occurred within the tongue of a 49-year-old man is described here. The difference from earlier cases occurring in the tongue is noted. Close follow-up has, as yet, revealed no 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