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   7314篇
  免费   426篇
  国内免费   63篇
耳鼻咽喉   68篇
儿科学   230篇
妇产科学   76篇
基础医学   862篇
口腔科学   127篇
临床医学   588篇
内科学   1740篇
皮肤病学   140篇
神经病学   524篇
特种医学   355篇
外科学   1298篇
综合类   168篇
一般理论   1篇
预防医学   283篇
眼科学   208篇
药学   322篇
中国医学   22篇
肿瘤学   791篇
  2024年   16篇
  2023年   82篇
  2022年   173篇
  2021年   314篇
  2020年   169篇
  2019年   214篇
  2018年   280篇
  2017年   186篇
  2016年   190篇
  2015年   203篇
  2014年   254篇
  2013年   350篇
  2012年   506篇
  2011年   526篇
  2010年   275篇
  2009年   239篇
  2008年   417篇
  2007年   421篇
  2006年   379篇
  2005年   419篇
  2004年   399篇
  2003年   325篇
  2002年   284篇
  2001年   151篇
  2000年   101篇
  1999年   107篇
  1998年   77篇
  1997年   67篇
  1996年   55篇
  1995年   44篇
  1994年   39篇
  1993年   26篇
  1992年   76篇
  1991年   62篇
  1990年   51篇
  1989年   54篇
  1988年   39篇
  1987年   29篇
  1986年   31篇
  1985年   21篇
  1984年   22篇
  1983年   16篇
  1982年   14篇
  1981年   14篇
  1980年   15篇
  1979年   16篇
  1978年   10篇
  1977年   9篇
  1975年   7篇
  1973年   7篇
排序方式: 共有7803条查询结果,搜索用时 15 毫秒
31.
A 69-year-old man was admitted to hospital because of sustainedventricular tachycardia with right bundle branch block morphology.After abolition of ventricular tachycardia, an electrocardiogramshowed atrial fibrillation, complete right bundle  相似文献   
32.
The utility of MRI using magnetization transfer (MT) enhanced pulse sequences to diagnose hepatic cirrhosis in a rat model was investigated. Hepatic T1 was measured with and without MT off-resonance RF pulses in 17 treated and six control rats. The livers were evaluated histologically, and the hydroxyproline content quantitatively measured. We did not find a statistically significant linear correlation between the MR relaxation times and the degree of tissue injury. However, the MR measurements performed with MT were superior to those without differentiating the treated and control groups. Specifically, the T1 times were 695 ±76 ms for the treated group, versus 748 ± 61 ms in the controls; P= 0.095. The T1sat times were also lower in the treated group, with statistical significance: 367 ± 51 ms versus 421 ± 38 ms, P = 0.016. Finally, the change in the relaxation rates (the inverse of the relaxation times) with and without saturation were 1.31 ± 0.22 s?1 (treated group) versus 1.05 ± 0.12 s?1 (controls), which differed significantly, P= 0.001.  相似文献   
33.
Several hormones, neurotransmitters, and neuropeptides were screened for the ability to stimulate inositol phosphate formation in cultured human retinal epithelial (RPE) cells. Carbachol, vasopressin and thrombin were found to be effective. Treatment of RPE cells with all three agents produced increases in inositol monophosphate, inositol bisphosphate and inositol trisphosphate in the presence of 10 mM LiCl. Carbachol stimulated a 4-fold increase in the total of inositol phosphates at 1 mM. Studies with cholinergic antagonists showed a rank order of 4 DAMP greater than QNX greater than pirenzepine greater than methoctramine, suggesting the presence of M3 muscarinic receptors. Vasopressin gave a 2.5-fold stimulation at 10 microM. Agonists of vasopressin were also tested and gave differential responses. Studies using a V1 agonist (PIOVP) and a V2 agonist (DAVP) showed DAVP matching the level of stimulation elicited by vasopressin whereas treatment with PIOVP only reached 50% of the vasopressin response. These data suggested the presence of V2 receptors in the RPE cells. Several proteases were tested for their ability to stimulate RPE inositol phosphates. Thrombin caused a 7-fold increase in inositol phosphate formation at 1 U/ml, whereas trypsin and plasmin elicited smaller responses (approximately 2-fold). The thrombin effect was blocked by the thrombin-specific inhibitor, hirudin, but not by other protease inhibitors. Several mediators of inflammation such as bradykinin, histamine and serotonin were also tested, and they were ineffective in stimulating inositol phosphate turnover in the RPE cells.  相似文献   
34.
Clinical diagnosis of chronic cholecystitis is made based on diffuse hyperechoic thickening of the gallbladder wall as shown by ultrasonographic examination. We herein report three cases of chronic cholecystitis showing localized hypoechoic thickening of the gallbladder wall that mimicked gallbladder cancer by ultrasonography. Histologically, hypertrophy of the muscularis propria was a common characteristic finding in these three patients. A smooth surface of the inner hypoechoic layer of the thickened wall was considered to be a reliable finding in the differential diagnosis between this type of chronic cholecystitis and gallbladder cancer.  相似文献   
35.
We describe an arthroscopic approach of tarsometatarsal arthrodesis for post-traumatic arthritis. Five tarsometatarsal portals (medial, P1–2, P2–3, P3–4, P4–5) are identified at the junctional points between the metatarsals by means of image intensifier. The first metatarsocuneiform joint is approached through the medial and P1–2 portal. Articular cartilage is denuded and micro-fracture of subchondral bone is performed with an arthroscopic awl. The second metatarsocuneiform joint is approached through the P1–2 and P2–3 portals and the third metatarsocuneiform joint is approached through the P2–3 and P3–4 portals. The articular surfaces are prepared for arthrodesis. The articulations are kept in desired position and transfixed with 4.0 mm cannulated screws. The fourth and fifth metatarsocuboid articulations are rarely included in the procedure. Arthroscopic arthrodesis or tendon arthroplasty of the lateral column can be performed through the P3–4 and P4–5 portals.  相似文献   
36.
We report a patient who developed overlapping symptoms of ophthalmoplegia and oropharyngeal palsy after Campylobacter jejuni infection. A 15-year-old man had diarrhea and fever, and developed dysarthria, diplopia and ptosis two weeks later. He did not show ataxia, weakness or abnormal tendon reflexes in the extremities during the clinical course. In the acute phase of the disease, we found significant elevation of anti-GQlb and anti-GTla IgG antibodies in the serum, and high-dose intravenous immunoglobulin therapy remarkably ameliorated the symptoms. Our patient was atypical of Fisher syndrome or pharyngeal-cervical-brachial (PCB) weakness, and this is the first case of multiple cranial neuropathy associated with C. jejuni infection.  相似文献   
37.
Adult septic cavernous sinus thrombosis (CST) due to Streptococcus constellatus infection has not been reported. We report a case of CST due to S. constellatus in a 39-year-old man who had typical presentations of septic CST including headache, fever, and ophthalmoplegia, with an evolving course for 10 days before he was sent to our emergency room. Cranial magnetic resonance imaging (MRI) study revealed CST, which was confirmed by cerebral angiography study. Multiple positive blood cultures grew viridans streptococci and further species identification with conventional methods, API-20 STREPT system analysis, and polymerase chain reaction sequencing of bacterial 16S rRNA revealed S. constellatus. The presence of sphenoid sinusitis in this patient was also demonstrated by cranial MRI study, and the presence of meningitis by meningeal irritation signs and inflammatory cerebrospinal fluid (CSF) findings. Chronic alcohol consumption for more than 10 years was the only predisposing condition to this infection. He had a full recovery after 6 weeks of intravenous penicillin G therapy (24 x 10(6) U/day). Almost complete regression of cavernous sinus lesion and resolution of sphenoid sinusitis were shown on follow-up cranial MRI study about 6 months later.  相似文献   
38.
BACKGROUND: Peritonitis is a serious complication of peritoneal dialysis (PD). We studied the efficacy of imipenem/cilastatin monotherapy in the treatment of PD-related peritonitis. METHODS: We performed an open-label, randomized control study comparing imipenem/cilastatin monotherapy (treatment group) versus cefazolin plus ceftazidime (control group) in the treatment of PD peritonitis. The result was further compared to a historic group treated with cefazolin plus netilmycin. Outcome measures were primary response rate at day 10 and complete cure rate. RESULTS: We enrolled 51 patients in the treatment group, 51 in the control group, and identified 96 in the historic group. The primary response rate to the assigned antibiotics was 49.0%, 51.0%, and 49.0% for the treatment, control, and historic groups, respectively (p = 0.97). The primary response rate allowing for change in antibiotic was 82.4%, 90.2%, and 82.3%, respectively, for the three groups (p = 0.41). The complete cure rate was 72.5%, 80.4%, and 82.3%, respectively (p = 0.60). Tenckhoff catheter removal was needed in 6 cases in the treatment group, 6 cases in the control group, and 13 cases in the historic group (p = 0.90). CONCLUSIONS: We concluded that monotherapy of imipenem/cilastatin has similar efficacy compared to the two standard regimens of cefazolin plus ceftazidime or netilmycin in the treatment of PD peritonitis.  相似文献   
39.
40.
Background. [123I]Metaiodobenzylguanidine (MIBG) imaging has been used to assess cardiac sympathetic nerve abnormalities. We evaluated the clinical significance of myocardial MIBG imaging as a measure of cardiac sympathetic nervous system function by comparing it to heart rate variability and plasma norepinephrine level.Methods and Results. In 211 subjects, we analyzed heart rate variability with 24-hour electrocardiography, performed scintigraphy with MIBG, and measured plasma norepinephrine levels. Time and frequency domain measures of heart rate variability were calculated with the Marquette heart rate variability program (Marquette Electronics, Milwaukee, Wis.). Early and late myocardial MIBG uptakes were measured at 15 and 150 minutes after injection, respectively. MIBG clearance rate from the heart and heart-to-lung and heart-to-mediastinum ratios of MIBG activities were calculated. On the whole, heart rate variability, including low-frequency power, correlated positively, but modestly so, with late MIBG uptake and negatively with MIBG clearance rate. The plasma norepinephrine level correlated negatively with late MIBG uptake and with heart rate variability, including low-frequency power, and positively with MIBG clearance rate. Similar correlations were also observed in patient subgroups with coronary artery disease, diabetes mellitus, and renal failure, but these correlations were weak (R2 < 0.5).Conclusions. Increased cardiac sympathetic nervous system activity may be associated with increased myocardial MIBG clearance and decreased heart rate variability, including low-frequency power. Because these associations were not strong, however, the combination of heart rate variability with MIBG may allow an interactive assessment of the cardiac autonomic nervous system.  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