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   3212篇
  免费   115篇
  国内免费   24篇
耳鼻咽喉   28篇
儿科学   46篇
妇产科学   27篇
基础医学   363篇
口腔科学   94篇
临床医学   217篇
内科学   953篇
皮肤病学   28篇
神经病学   155篇
特种医学   112篇
外科学   618篇
综合类   5篇
预防医学   43篇
眼科学   25篇
药学   253篇
中国医学   14篇
肿瘤学   370篇
  2023年   24篇
  2022年   23篇
  2021年   54篇
  2020年   19篇
  2019年   37篇
  2018年   34篇
  2017年   31篇
  2016年   44篇
  2015年   31篇
  2014年   55篇
  2013年   71篇
  2012年   106篇
  2011年   118篇
  2010年   43篇
  2009年   59篇
  2008年   109篇
  2007年   109篇
  2006年   159篇
  2005年   168篇
  2004年   195篇
  2003年   169篇
  2002年   169篇
  2001年   168篇
  2000年   168篇
  1999年   163篇
  1998年   54篇
  1997年   49篇
  1996年   35篇
  1995年   43篇
  1994年   31篇
  1993年   31篇
  1992年   91篇
  1991年   74篇
  1990年   69篇
  1989年   66篇
  1988年   67篇
  1987年   81篇
  1986年   59篇
  1985年   63篇
  1984年   24篇
  1983年   34篇
  1982年   11篇
  1980年   8篇
  1979年   18篇
  1978年   15篇
  1977年   23篇
  1976年   9篇
  1975年   8篇
  1974年   12篇
  1973年   10篇
排序方式: 共有3351条查询结果,搜索用时 78 毫秒
81.
OBJECTIVE: To investigate the link between a reduction in blood pressure (BP) and daily exercise. DESIGN: Cross-sectional and longitudinal clinical intervention study with exercise education. SUBJECTS: 43 overweight Japanese men aged 32-59 years (BMI, 29.0+/-2.3 kg/m2) at baseline. Among the participants, a randomly selected 23 overweight men (BMI, 28.5+/-1.7) were further enrolled into the 10 months exercise program. MEASUREMENTS: BP was measured every week and steps per day were also recorded every day throughout the observation period. Fat distribution was evaluated by visceral fat (V) and subcutaneous fat (S) areas measured with computed tomography (CT) scanning at umbilical level, at before, 5 months and after intervention. Anthropometric parameters were also measured at same point. Aerobic exercise level, muscle strength, flexibility and calorie intake and insulin resistance (HOMA index) were investigated at before and after the study. RESULTS: In a cross sectional analysis, systolic BP (SBP) and diastolic BP (DBP) were significantly correlated with body composition. In a second longitudinal analysis, SBP was significantly reduced at 2 months and DBP was also reduced at 3 months, and almost maintained until the end of the observation period. Increasing daily walking was observed in 3 months and maintained until 10 months. Body composition, aerobic exercise level, muscle strength, flexibility and insulin resistance were significantly improved. There was positive correlation between DeltaDBP and Deltavisceral fat area (1-5, 5-10, 1-10 months). By stepwise multiple regression analysis, only Deltavisceral fat area was independently related to DeltaDBP at a significant level (1-10 months: DeltaDBP=-0.608+0.105Deltavisceral fat area, r2=0.227, P=0.0334). CONCLUSION: The present study indicated daily exercise lowers BP and visceral fat area is the critical factor for BP change.  相似文献   
82.
83.
BACKGROUND: Cyclosporine (CsA), Mycophenolate mofetil (MMF) and prednisolone (PSL) are widely used for the prevention of acute rejection after heart transplantation. Recently, the serum concentration - time curves (AUC) of CsA and MMF have been demonstrated to be precise predictors of acute rejection. METHODS AND RESULTS: Fourteen heart transplant patients were treated concomitantly with CsA, MMF, and PSL between May 1999 and November 2005 at the National Cardiovascular Center and of them 3 had acute rejection episodes [International Society for Heart & Lung Transplantation grade 3a]. Two patients (man in his 30 s; woman in her 40 s) had acute rejection with a mycophenolic acid (MPA) AUC(0-12 h) <30 microg x h x ml(-1) and low CsA AUC (AUC(0-4 h); 2,408 ng x h x ml-1, 1,735 ng x h x ml-1). However, 1 patient (man in his 30 s) with a high CsA AUC(0-4 h) (4,019 ng x h x ml-1) did not develop cardiac allograft rejection even if the MMF was temporarily stopped. These 3 patients were investigated to evaluate the relationship between acute rejection and pharmacokinetic parameters, including the CsA C0, C2, AUC(0-4 h) and MPA AUC(0-12 h). CONCLUSIONS: The findings suggest that a high CsA AUC(0-4 h) may prevent rejection of a cardiac allograft, even if MMF is stopped or drastically reduced.  相似文献   
84.
The patient, a 20-year-old male, was found to have a slightly prolonged prothrombin time (PT). No episodes of bleeding were noted. The measurement of coagulation factors revealed that the level of factor X (FX) activity was solely deficient, 51% (normal range: 70–130% ), and that of FX antigen was 100%. Analysis of the entire FX gene revealed the novel missense mutation of GTG to ATG, resulting in the substitution of the 196th amino acid valine → methionine. The mother and younger brother had a normal PT time and expressed no episode of bleeding. The mother exhibited a normal level of FX activity and antigen; however the younger brother showed a slight decrease in both the parameters. This mutation was not observed in the mother and younger brother. Polymorphism is not observed at this point in healthy persons. The present novel FX mutation was named FX Hofu.  相似文献   
85.
Serum lysozyme is used as a marker of sarcoidosis disease activity. In this study we examined the association between lysozyme levels and the clinical features of sarcoidosis and thus the clinical usability of this parameter in a large population. One hundred ten sarcoidosis patients from central Japan were examined for clinical features and serum lysozyme level at the first visit to our hospital and on a regular basis thereafter. The sensitivity of lysozyme for predicting sarcoidosis was 79.1%, whereas that of serum angiotensin-converting enzyme (ACE) was 59.0%. Even in the cases without an elevated serum ACE level, a value of 72.1% was obtained. The serum lysozyme level demonstrated a significant tendency to increase with the number of organs involved (p < 0.01). There were significant differences among the four radiographic stages (p < 0.05). The maximum serum lysozyme levels of patients without a disappearance of abnormal shadows on chest radiography within 5 years were significantly greater than those of individuals with a disappearance (p < 0.05). A positive correlation between serum lysozyme and serum ACE levels was observed. Because serum lysozyme is much less specific for sarcoidosis than serum ACE, its diagnostic value may be limited. However, the sensitivity was high even when serum ACE levels were within normal limits and correlated well with clinical features in sarcoidosis. Therefore, this parameter seems suitable for disease monitoring in proven cases. Accepted for publication: 19 November 1998  相似文献   
86.
We report a case of pulmonary thromboembolism, in which obstruction of the right subclavian vein, also called Paget-von Schroetter syndrome, was detected. The patient was a 39-year-old man (a scaffold constructor). He lost consciousness at work, and was admitted as an emergency case to our hospital. He had noticed gradually worsening dyspnea for 1 month. Chest radiography showed Westmark's sign in the lungs and enlarged hilar vascular markings on both sides. Pulmonary perfusion scintigraphy confirmed multiple flow defects. Upper and lower limb venography disclosed interruption of the right subclavian vein, leading to a diagnosis of pulmonary thromboembolism secondary to upper limb vein thrombosis. In patients who have pulmonary thromboembolism without an apparent underlying disease, the lifestyle and work habits should be considered and the possibility of subclavian vein thrombosis should be kept in mind.  相似文献   
87.
Previous studies have found markedly elevated serum concentrations of proinflammatory cytokines in patients with Graves’ disease (GD). We investigated the role of macrophage colony-stimulating factor (M-CSF) in GD. We assayed concentrations of M-CSF in sera from 32 patients with GD (25 untreated; 7 receiving thiamazole therapy). We also studied 32 age-matched healthy subjects as controls. Relationships between serum M-CSF and both thyroid state and serum lipids were examined. Moreover, to examine the effect of thyroid hormone alone on serum M-CSF, T3 was administered orally to normal subjects. Serum concentrations of M-CSF in GD patients who were hyperthyroid were significantly increased compared with GD patients who were euthyroid (P < 0.05) and control subjects (P < 0.0001). Serum M-CSF concentrations correlated closely with T3 levels in patients (= 0.51, < 0.005). Serial measurement of five individual patients revealed that serum concentrations of M-CSF were significantly decreased (P < 0.05), reaching normal control values upon attainment of euthyroidism. Furthermore, oral T3 administered to 15 volunteers for 7 days produced significant increases in serum levels of M-CSF (< 0.05). The close correlation between serum M-CSF and serum thyroid hormone levels suggests that high circulating levels of thyroid hormones may directly or indirectly potentiate the production of M-CSF in patients with GD.  相似文献   
88.
89.
A new human myeloma cell line NOP-2, producing immunoglobulin (Ig)-lambda-light chain was established from a patient with Bence Jones-type multiple myeloma. Morphologically, the cell line had plasmacytoid characteristics by light- and electron-microscopic examination. Phenotypic studies of NOP-2 cells revealed no surface Ig, but they were positive for cytoplasmic Ig-lambda, OKT10 (CD 38), and PCA-1. Epstein-Barr nuclear antigen was not detected. Chromosomal abnormalities of t(11;14) and t(8;22) were found in both NOP-2 cells and the original myeloma cells obtained from the patient. NOP-2 cells produced and secreted Ig-lambda light chain, but lacked immunoglobulins of any heavy chains. Rearrangements of both immunoglobulin heavy- and light-chain genes were observed in NOP-2 cells, though the cells expressed detectable mRNA only for Ig-lambda light chain. This cell line may serve as a useful model for understanding the hierarchy of human immunoglobulins and the pathophysiology of Bence Jones-type multiple myeloma.  相似文献   
90.
We studied the effect of fibrinogen degradation products D, E, and D-dimer on a human promonocytic leukemia cell line, NOMO-1. After exposure to a 10(-5)-mol/L fragment D or D-dimer, the cells displayed macrophage-like characteristics, such as adherence to plastic surfaces, and showed approximately a twofold increase in response to the nitroblue tetrazolium reduction test. The secretion of interleukin-1 alpha (IL-1 alpha) into the medium was markedly stimulated by a 10(-5)-mol/L fragment D, E, and D-dimer, whereas a significant increase in IL-1 beta secretion was observed only in D-dimer-stimulated cells. In addition, D-dimer induced a rapid increase in urokinase-type plasminogen activator on day 1 (0.52 +/- 0.02 ng/mL v 0.07 +/- 0.01 ng/mL in the control culture) and a slow increase in plasminogen activator inhibitor-2 on day 5 (3.9 +/- 1.6 ng/mL v 1.2 +/- 0.2 ng/mL in the control culture). An increase in tissue factor (TF) was also demonstrated on the cell surface of NOMO-1 cells exposed to fragment D or D-dimer by indirect immunofluorescence using an anti-TF monoclonal antibody. Scatchard plot analysis showed that fragment D and D-dimer bound to the NOMO-1 cells with a kd of 3.3 nmol/L and 2.7 nmol/L, respectively. These results suggest that fragment D-dimer specifically stimulates cells of monocyte-macrophage lineage to secrete key substances that regulate blood coagulation, fibrinolysis, and inflammation.  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