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   10400篇
  免费   509篇
  国内免费   67篇
耳鼻咽喉   152篇
儿科学   152篇
妇产科学   109篇
基础医学   1455篇
口腔科学   293篇
临床医学   643篇
内科学   2910篇
皮肤病学   93篇
神经病学   739篇
特种医学   363篇
外科学   1465篇
综合类   38篇
预防医学   310篇
眼科学   361篇
药学   859篇
中国医学   12篇
肿瘤学   1022篇
  2023年   53篇
  2022年   97篇
  2021年   168篇
  2020年   103篇
  2019年   132篇
  2018年   172篇
  2017年   121篇
  2016年   204篇
  2015年   196篇
  2014年   226篇
  2013年   295篇
  2012年   475篇
  2011年   534篇
  2010年   324篇
  2009年   255篇
  2008年   505篇
  2007年   539篇
  2006年   517篇
  2005年   545篇
  2004年   558篇
  2003年   562篇
  2002年   548篇
  2001年   337篇
  2000年   326篇
  1999年   285篇
  1998年   166篇
  1997年   113篇
  1996年   103篇
  1995年   77篇
  1994年   86篇
  1993年   73篇
  1992年   226篇
  1991年   180篇
  1990年   178篇
  1989年   177篇
  1988年   174篇
  1987年   161篇
  1986年   138篇
  1985年   116篇
  1984年   101篇
  1983年   72篇
  1982年   50篇
  1981年   42篇
  1979年   76篇
  1978年   57篇
  1976年   46篇
  1972年   45篇
  1971年   42篇
  1970年   42篇
  1968年   45篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Morning blood pressure is reported to be more closely related to hypertensive organ damages such as left ventricular mass index, microalbuminuria and silent cerebral infarcts, than blood pressure at other times of the day. Morning blood pressure may play an important role in the pathogenesis of hypertensive target organ damage. Increased sympathetic nerve activity is reported to be one of the mechanisms of morning hypertension; however, there are no available data that show whether strict home blood pressure control, especially in the morning period, can reduce target organ damage. The Japan Morning Surge-1 (JMS-1) study includes hypertensive outpatients with elevated morning systolic blood pressure (>or=135 mmHg) as assessed by self-measured blood pressure monitoring at home. All enrolled patients are under stable antihypertensive medication status. Exclusion criteria are arrhythmia, chronic inflammatory disease, and taking alpha-blockers or beta-blockers. The target number of patients to be enrolled in the JMS-1 study is 600, and the aim is to evaluate differences in the markers of hypertensive target organ damage, such as brain natriuretic peptide and the urinary albumin excretion/creatinine ratio. All of the patients are randomized to an experimental group or a control group, with randomization to be carried out by telephone interviews with the patients' physicians. In the experimental group, patients begin taking additional antihypertensive medication just before going to bed. This consists of doxazosin 1 mg/day, which then is increased to 2 mg/day and 4 mg/day, with a beta-blocker added after a 1-month interval until the morning systolic blood pressure is controlled to less than 135 mmHg. Patients in the control group continue the treatment they are receiving at the enrollment for 6 months. Blood pressure levels, adverse effects, and hypertensive target organ damage before and after the study are evaluated. In the JMS-1 study, we will evaluate whether strict morning blood pressure control by sympathetic nervous system blockade using an alpha-blocker, doxazosin, and with the addition of a beta-blocker if needed, can reduce hypertensive target organ damage.  相似文献   
22.
23.
BACKGROUND: Myocardial perfusion single photon emission computed tomography (SPECT) occasionally fails to detect coronary stenosis in patients with coronary artery disease (CAD). We evaluated coronary flow reserve (CFR) using oxygen 15-labeled water in areas with and without ischemia on technetium 99m tetrofosmin stress perfusion SPECT in patients with angiographically documented CAD. METHODS AND RESULTS: Twenty-seven patients with CAD and eleven age-matched normal subjects were studied. Baseline myocardial blood flow (MBF) and MBF during hyperemia induced by intravenous adenosine triphosphate infusion (0.16 mg. kg(-1). min(-1)) were determined with the use of O-15-labeled water positron emission tomography, and the CFR was calculated. Tc-99m tetrofosmin stress/rest SPECT was performed for comparison. On the basis of the results of coronary angiography and SPECT, coronary segments were divided into 3 types: segments with coronary stenosis and a perfusion abnormality on stress SPECT imaging (group A, n = 16), segments with coronary stenosis without a perfusion abnormality (group B, n = 42), and remote segments with no coronary stenosis or perfusion abnormality (group C, n = 18). Baseline MBF values were similar among the 3 groups. CFR in group A was lower (1.82 +/- 0.54) than in group B (2.22 +/- 0.87, P <.05), in group C (2.92 +/- 1.21, P <.01), and in normal segments (3.86 +/- 1.24, P <.001). CFR in group B was lower than in group C (P <.02) and in normal segments (P <.001). CFR in group C was lower than in normal segments (P <.02). CONCLUSIONS: Areas with a perfusion abnormality on stress SPECT had reduced CFR. In the areas without a perfusion abnormality and with coronary stenosis, lowering of CFR was intermediate between the areas with a perfusion abnormality and remote segments. Moreover, CFR was slightly, but significantly, lower in remote segments in patients with CAD compared with normal segments.  相似文献   
24.
While serum magnesium (Mg) level is increased in patients with end-stage renal disease (ESRD), it is decreased in renal transplant recipients (TR) receiving ciclosporin. This study was performed to examine the cation metabolism of red blood cells (RBC) in these patients. Intracellular free Mg was measured with 31P-nuclear magnetic resonance spectrometry, and ouabain-sensitive sodium (Na) efflux rate (Eos) was measured from the increase in RBC-Na concentration when RBC were incubated in the presence of ouabain. The ouabain-sensitive Na efflux rate constant (ERCos) was obtained by dividing Eos by RBC-Na concentration. RBC free Mg and ERCos were significantly higher in the TR group than in the ESRD group. There was a significant correlation between RBC free Mg and ERCos (r = 0.474, p less than 0.01). These results support the views that the regulation mechanism for intracellular free Mg is different from that for extracellular Mg in patients with renal disease, and intracellular free Mg modulates Na pump activity of RBC.  相似文献   
25.
The effect of reflux of the duodenal contents on the development of gastric stump carcinoma without carcinogen in rats was studied. At the first experiment, seventy male Wistar rats were subjected to gastrojejunostomy for the diversion of duodenal contents into the resected stomach through the afferent and the efferent loops. The incidence of adenocarcinoma in the afferent anastomosis were 0/8 (0%) at the 10th week, 3/16 (18.8%) at the 20th week and 7/20 (35%) at the 40th week, so the incidence was apt to rise in parallel to the time. In the second experiment, ninety rats were divided into 4 groups: Group I received the same operation as the first experiment, group II received the operation with Braun's anastomosis, group III received the operation for reflux of bile alone to the remnant stomach, and group IV received the operation for reflux of pancreatic juice alone. Animals surviving after surgery were sacrificed at the 40th week. The incidence were 33.3% in group I, 0% in group II, 0% in group III, and 8.3% in group IV, respectively. These findings suggest that reflux of duodenal contents (both bile and pancreatic juice) is an important factor in the gastric stump carcinogenesis.  相似文献   
26.
27.
The effects of alminoprofen, a nonsteroidal anti-inflammatory agent, on the experimental animal models of allergic reactions were examined and compared with those of ibuprofen. Alminoprofen at 30 mg/kg given intraduodenally significantly suppressed passive anaphylactic bronchoconstrictions, while ibuprofen did not at the same doses. In vitro studies revealed that alminoprofen, in contrast to ibuprofen, exerted an inhibitory effect on arachidonate 5-lipoxygenase activity which initiates the bio-synthesis of leukotrienes. Alminoprofen inhibited arachidonic acid-induced ear edema in mice and homologous passive cutaneous anaphylaxis in rats at high doses, while ibuprofen did not at the high doses. From its characteristic feature of inhibitory effects on 5-lipoxygenase activity and the experimental model of type I allergic reaction, it is suggested that alminoprofen is a new type of nonsteroidal anti-inflammatory agent.  相似文献   
28.
Antibodies to 3-methoxy-4-aminoazobenzene (3-MeO-AAB) and 2-methoxy-4-aminoazobenzene (2-MeO-AAB) DNA adducts were raised in rabbits against in vitro-adducted DNA samples. The enzyme-linked immunosorbent assay (ELISA) was used to determine the sensitivity and specificity of these antibodies. They proved highly specific for the modified DNA used as the immunogen, but cross-reacted with each other. Moreover, they showed cross reactivity with DNA modified by 4-( o -tolylazo)- o -toluidine, but not by other carcinogens, such as 4-aminobiphenyl or 4-nitroquinoline 1-oxide. The 50% inhibition level of antibody binding in the competitive ELISA was at 10–20 fmol of modified base per assay (equivalent to 1–2 adducts per 106 bases). Immunohistochemical staining indicated that these antibodies bind specifically to nuclear components of the liver in rats given either 3-MeO-AAB or 2-MeO-AAB at the dose of 50 mg/kg body weight.  相似文献   
29.
A 50-year-old woman with anorexia nervosa was admitted for evaluation of neutropenia (WBC 1,600/microliters). Her bone marrow was gelatinous, and myeloid cells had decreased. Homogeneous substance deposited in the marrow, stained by alcian blue (pH 2.5), indicative of acid mucopolysaccharides. CFU-G and CFU-GM were decreased in number and myeloid pool in the bone marrow also decreased. Anti-neutrophilic antibody was negative. Neutropenia may be related to myeloid hypoplasia, due to increase of acid mucopolysaccharides replacing adipose cells in the bone marrow under long-term mal-nutritional state. Neutrophils markedly increased by administration of rhG-CSF 5.0 micrograms/kg/day for 14 days without the first peak. Serum G-CSF level did not increase (less than 60 pg/ml). It is effective to administer G-CSF to anorexia nervosa with neutropenia.  相似文献   
30.
Palmar advancement flap with V-Y closure for thumb tip injuries   总被引:1,自引:0,他引:1  
The palmar advancement flap with V-Y closure was used in two patients with thumb tip injuries. This technique allows more distal advancement of the flap than does a conventional palmar advancement flap and does not require skin graft coverage.  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