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   8048篇
  免费   490篇
  国内免费   50篇
耳鼻咽喉   77篇
儿科学   186篇
妇产科学   308篇
基础医学   1035篇
口腔科学   137篇
临床医学   733篇
内科学   1861篇
皮肤病学   115篇
神经病学   734篇
特种医学   248篇
外科学   1179篇
综合类   60篇
一般理论   5篇
预防医学   431篇
眼科学   194篇
药学   601篇
中国医学   35篇
肿瘤学   649篇
  2023年   56篇
  2022年   181篇
  2021年   315篇
  2020年   134篇
  2019年   188篇
  2018年   241篇
  2017年   196篇
  2016年   199篇
  2015年   222篇
  2014年   274篇
  2013年   411篇
  2012年   588篇
  2011年   588篇
  2010年   343篇
  2009年   293篇
  2008年   455篇
  2007年   468篇
  2006年   454篇
  2005年   437篇
  2004年   409篇
  2003年   351篇
  2002年   295篇
  2001年   148篇
  2000年   124篇
  1999年   117篇
  1998年   73篇
  1997年   42篇
  1996年   48篇
  1995年   53篇
  1994年   51篇
  1993年   45篇
  1992年   80篇
  1991年   55篇
  1990年   52篇
  1989年   56篇
  1988年   47篇
  1987年   41篇
  1986年   20篇
  1985年   29篇
  1984年   36篇
  1983年   17篇
  1982年   13篇
  1981年   16篇
  1980年   14篇
  1979年   24篇
  1978年   16篇
  1975年   13篇
  1971年   19篇
  1969年   16篇
  1967年   14篇
排序方式: 共有8588条查询结果,搜索用时 15 毫秒
31.
Purpose To evaluate the clinical results of percutaneous transluminal rotational atherectomy in the treatment of peripheral vascular disease. Methods Rotational atherectomy was performed in 39 patients aged 39–87 years (mean 66.6 years). A total of 71 lesions (43 stenoses and 28 occlusions) were treated in 40 limbs. Additional balloon angioplasty was required in 54% of lesions. Fifteen patients (37.5%) presented in Fontaine stage II, 10 patients (25%) in Fontaine stage III and 15 patients (37.5%) in Fontaine stage IV. Rotational atherectomy at 750 rpm was carried out over a 0.014-inch guidewire with continuous aspiration into a vacuum, bottle. Follow-up angiography and color flow Doppler examinations were performed in 22 patients (23 limbs) after a mean period of 6 months (range 2–14 months) Results There was one primary technical failure. In 36 of 40 lesions there was a good angiographic result with residual stenoses in less than 30%. In 70 lesions treated by rotational atherectomy, however, 54% showed residual stenoses of 30%–50% and these cases required additional balloon angioplasty. The mean ankle-brachial index improved significantly (p<0.001), from 0.49 before the procedure to 1.01 after the procedure. A single distal embolus, related to primary recanalization, occurred and there were two large inguinal hematomas. Cumulative clinical patency after 6 months was 83.8% and cumulative angiographic patency after 6 months was 79.1%. Conclusion Percutaneous rotational atherectomy is a promising approach for the treatment of chronic peripheral vascular disease. Further prospective, randomized studies are necessary to compare percutaneous transluminal angioplasty with this new technical approach.  相似文献   
32.
In this paper the authors evaluate the long-term results of treatment for articular calcaneus fractures with Westhues method. This evaluation is performed with regard to triple measurement of B?hler's angle value and to subjective criteria. The clinical material from years 1985-2002 consists of 47 patients aged between 24 and 56 years (mean age 32 years) with articular calcaneus fractures--namely, 41 male patients (87.2%) and 6 female patients (12.8%). The follow-up examination was performed in 24 patients (51% of all patients), namely, in 23 male patients (48.8%) and in one female patient (2.2%). Minimum follow-up time was 12 months and maximum was 9 years. Acquired results suggest that Westhues method restores normal B?hler's angle value only in tongue-type calcaneous fractures.  相似文献   
33.
HU-211 is a synthetic, non-psychotropic cannabinoid which acts as a non-competitive NMDA antagonist and antioxidant. We studied the drug's therapeutic window as well as its long-term effect on cognitive and motor functions in a model of closed head injury (CHI) in the rat. A weight-drop device was used to induce CHI in ether anesthetized male rats. HU-211 (5 mg/kg) was administered i.v. to the experimental groups. For the therapeutic window study, drug was injected at 4 or 6 h after CHI. Edema (water content) and clinical status (neurological severity score, NSS) were evaluated at 24 h. Reduction of edema was slight, whereas improvement of NSS was significant when the drug was administered at 4 or 6 h (P = 0.0023and0.059, respectively). To determine the drug's long-term effect, it was administered 1 h after CHI and additional doses were later given. NSS was evaluated for a period of 30 d. A single dose of HU-211 given 1 h post-CHI improved the clinical outcome during the 30 d period (P < 0.01). Repetitive doses of HU-211 injected during the post traumatic period had similar effects. Cognitive functions were evaluated in the Morris water maze, with rats trained either before or after CHI. CHI resulted in a highly significant impairment of these abilities, whereas HU-211 treatment 1 h after CHI improved performance. Our results indicate that HU-211 is a potent cerebroprotective agent, with a therapeutic window of about 4 h. The beneficial response obtained even after a single dose was long lasting, and ameliorated impairment of both motor and cognitive functions following CHI.  相似文献   
34.
Summary We examined 81 men exposed for a long time to carbon disulphide (CS2) and tested the possible electrocardiographic (ECG) changes of ischemic heart disease (I.H.D.). The subjects were examined twice in two years. In order to make the ECG evaluation more objective, the Minnesota Code was applied. Two obligatory ECG examinations and only one submaximal effort test were carried out. For comparative evaluation, the control group was examined once. We proved that, in spite of the accepted opinion concerning the atheromatous action of CS2, this compound does not cause ECG symptoms of I.H.D. in a higher percentage of exposed persons. It also does not cause any significant increase in I.H.D. symptoms in dynamic ECG observations.  相似文献   
35.
This study was aimed at evaluating the efficacy of chemoembolization (CE) to improve survival in patients with hepatocellular carcinoma (HCC). Our results were compared with the natural history of HCC. Sixty-two consecutive patients with HCC in Okuda's stages I and II underwent CE. Forty-seven patients were treated with CE alone; 9 patients had CE prior to surgery, and 6 patients had it after surgery because of recurrent HCC. One hundred and nine CEs (mean: 1.8 CEs/patient) were performed with Lipiodol UF, epirubicin and gelatin sponge. Actuarial survival was calculated considering Okuda's stage, neoplasm size, and evidence of pseudocapsule. The mean cumulative survival of the 47 patients treated with CE alone was 13.2 months; survival (+/- SE) at 12, 24 and 36 months was 0.75 (+/- 0.07), 0.46 (+/- 0.10) and 0.28 (+/- 0.12). Survival was not affected by Okuda's stage, neoplasm size, evidence of pseudocapsule (p > 0.05). Nevertheless, the patients with early HCC had better prognosis. Eighteen patients (42.9%) died during follow-up, 12 of whom (66.7%) from hepatic failure. The mean survival of patients with recurrence of HCC after surgery was 41 months (range: 24.8-74.9 months) since initial diagnosis of HCC, and 14.8 months (range: 7.1-29.6 months) since diagnosis of recurrence. Two of these patients died from hepatic failure. All the patients who underwent also surgery after CE are still alive (mean survival: 14.7 months). Histologic findings of resected specimens revealed viable neoplastic cells in all cases. Twenty-one major complications (20.2%) occurred in 18 patients (29%); the outcome of complications was favorable in all but one patient who died from sepsis. CE is a reliable and safe treatment for unresectable HCC. Small HCCs should be preferably treated with surgery or, alternatively, with percutaneous alcohol injection.  相似文献   
36.
Abdominal complications of intestinal surgery are an important cause of postoperative morbidity and mortality. We define early complications as those occurring within the first 30 days after surgery. The radiological contribution towards prompt and accurate diagnosis of common complications is discussed and the radiologist's role in non-operative management is outlined.  相似文献   
37.
38.
39.
Advanced glycation end products (AGEs), the final products of nonenzymatic glycation and oxidation of proteins, are found in the plasma and accumulate in the tissues during aging and at an accelerated rate in diabetes. A novel integral membrane protein, termed receptor for AGE (RAGE), forms a central part of the cell surface binding site for AGEs. Using monospecific, polyclonal antibody raised to human recombinant and bovine RAGE, immunostaining of bovine tissues showed RAGE in the vasculature, endothelium, and smooth muscle cells and in mononuclear cells in the tissues. Consistent with these data, RAGE antigen and mRNA were identified in cultured bovine endothelium, vascular smooth muscle, and monocyte-derived macrophages. RAGE antigen was also visualized in bovine cardiac myocytes as well as in cultures of neonatal rat cardiac myocytes and in neural tissue where motor neurons, peripheral nerves, and a population of cortical neurons were positive. In situ hybridization confirmed the presence of RAGE mRNA in the tissues, and studies with rat PC12 pheochromocytes indicated that they provide a neuronal-related cell culture model for examining RAGE expression. Pathological studies of human atherosclerotic plaques showed infiltration of RAGE-expressing cells in the expanded intima. These results indicate that RAGE is present in multiple tissues and suggest the potential relevance of AGE-RAGE interactions for modulating properties of the vasculature as well as neural and cardiac function, prominent areas of involvement in diabetes and in the normal aging process.  相似文献   
40.
Five modern bicycle helmets were studied to elucidate some of the variations in ventilation performance, using both a heated manikin headform and human subjects (n=7). Wind speed and head angle were varied to test their influence on the measured steady-state heat exchange (cooling power) in the skull section of the headform. The cooling power transmitted by the helmets varied from about 60% to over 90% of that of the nude headform, illustrating the range of present manufacturer designs. Angling the head forward by 30° was found to provide better cooling power to the skull (up to 25%) for three of the helmets and almost equal cooling power in the remaining two cases. Comparisons of skull ventilation at these angles with human subjects strongly supported the headform results.  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