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   4841篇
  免费   232篇
  国内免费   43篇
耳鼻咽喉   11篇
儿科学   106篇
妇产科学   58篇
基础医学   642篇
口腔科学   99篇
临床医学   268篇
内科学   1336篇
皮肤病学   398篇
神经病学   243篇
特种医学   155篇
外科学   967篇
综合类   16篇
预防医学   110篇
眼科学   69篇
药学   204篇
中国医学   11篇
肿瘤学   423篇
  2023年   27篇
  2022年   76篇
  2021年   134篇
  2020年   74篇
  2019年   91篇
  2018年   140篇
  2017年   100篇
  2016年   100篇
  2015年   129篇
  2014年   169篇
  2013年   188篇
  2012年   324篇
  2011年   327篇
  2010年   183篇
  2009年   159篇
  2008年   274篇
  2007年   287篇
  2006年   294篇
  2005年   283篇
  2004年   278篇
  2003年   307篇
  2002年   288篇
  2001年   57篇
  2000年   60篇
  1999年   61篇
  1998年   71篇
  1997年   58篇
  1996年   50篇
  1995年   42篇
  1994年   44篇
  1993年   37篇
  1992年   42篇
  1991年   46篇
  1990年   25篇
  1989年   30篇
  1988年   33篇
  1987年   21篇
  1986年   19篇
  1985年   24篇
  1984年   16篇
  1983年   15篇
  1982年   12篇
  1981年   9篇
  1980年   9篇
  1979年   14篇
  1978年   9篇
  1975年   8篇
  1974年   12篇
  1972年   8篇
  1971年   9篇
排序方式: 共有5116条查询结果,搜索用时 31 毫秒
41.
Sixty-four patients with persistent asthma receiving 200 to 800 μ g of fluticasone propionate daily were enrolled in this switchover study. The patients applied a tulobuterol patch 2 mg every 24 hours for 4 weeks followed by inhalation of salmeterol 100 μ g bid for 4 weeks. The mean values for morning and evening peak expiratory flow improved significantly compared with baseline during the 4 weeks of tulobuterol patch treatment. Further improvement was seen on switching to salmeterol treatment, which was significant even in the first week, and continued until the final week of the study. Use of salmeterol alone resulted in a significant increase in the percentage of forced expiratory volume in 1 second %FEV1 from baseline, with 51% of patients feeling that the treatment was effective (vs. 37% on tulobuterol). These data suggest that salmeterol can achieve better control in asthmatic patients after switching from using tulobuterol patches.  相似文献   
42.
Cryopyrin-associated periodic syndrome (CAPS) is a spectrum of systemic autoinflammatory disorders in which the majority of patients have mutations in the cold-induced autoinflammatory syndrome (CIAS)1 gene. Despite having indistinguishable clinical features, some patients lack CIAS1 mutations by conventional nucleotide sequencing. We recently reported a CAPS patient with mosaicism of mutant CIAS1, and raised the possibility that CIAS1 mutations were overlooked in "mutation-negative" patients, due to a low frequency of mosaicism. To determine whether there were latent mutant cells in "mutation-negative" patients, we sought to identify mutation-associated biologic phenotypes of patients' monocytes. We found that lipopolysaccharide selectively induced necrosis-like cell death in monocytes bearing CIAS1 mutations. Monocyte death correlated with CIAS1 up-regulation, was dependent on cathepsin B, and was independent of caspase-1. Cell death was intrinsic to CIAS1-mutated monocytes, was not mediated by the inflammatory milieu, and was independent of disease severity or anti-IL-1 therapy. By collecting dying monocytes after lipopolysaccharide treatment, we succeeded in enriching CIAS1-mutant monocytes and identifying low-level CIAS1-mosaicism in 3 of 4 "mutation-negative" CAPS patients. Our findings reveal a novel effect of CIAS1 mutations in promoting necrosis-like cell death, and demonstrate that CIAS1 mosaicism plays an important role in mutation-negative CAPS patients.  相似文献   
43.
44.
45.
Fast MR imaging in obstetrics.   总被引:8,自引:0,他引:8  
Ultrasonography (US) is the initial imaging modality of choice for evaluation of patients in obstetrics. However, the results of US are not always sufficient. Magnetic resonance (MR) imaging, which uses no ionizing radiation, may be an ideal method for further evaluation. Although MR imaging is not recommended during the first trimester and use of contrast material is not recommended in pregnant patients, fast MR imaging is useful in various obstetric settings and can provide more specific information with excellent tissue contrast and multiplanar views. In pregnant patients with acute conditions, various diseases (eg, red degeneration of a uterine leiomyoma) may be diagnosed. MR imaging allows characterization of pelvic masses discovered during pregnancy and diagnosis of postpartum complications (eg, abscess, hematoma, ovarian vein thrombosis). In pregnant patients with hydronephrosis, MR urography can demonstrate the site of obstruction and the cause (eg, a ureteral stone). MR pelvimetry may be beneficial in cases of breech presentation. Contrast material-enhanced dynamic MR imaging allows one to evaluate the vascularity of a placental polyp, detect the viable component of a gestational trophoblastic tumor, and diagnose a uterine arteriovenous malformation. MR imaging enables diagnosis of rare forms of ectopic pregnancy and early diagnosis of ectopic pregnancy.  相似文献   
46.
BACKGROUND: Hemodialysis patients have advanced arterial wall stiffening as shown by increased aortic pulse wave velocity (PWV), an independent predictor of cardiovascular mortality. We compared aortic PWV of uremic patients before starting hemodialysis treatment with that of patients on maintenance hemodialysis. METHODS: The subjects were 71 patients with end-stage renal disease (ESRD) before starting hemodialysis (predialysis group), 144 patients on maintenance hemodialysis, and 140 healthy control subjects. These three groups were all nondiabetic and comparable in age and gender. RESULTS: The hemodialysis group had greater aortic PWV than the healthy subjects, and the predialysis patients showed a still higher value than the hemodialysis group. Multiple regression analysis in the total subjects revealed that the presence of renal failure was significantly associated with increased aortic PWV independent of age, gender, blood pressure, body mass index, smoking, high-density lipoprotein (HDL) and nonhigh-density lipoprotein (non-HDL) cholesterol levels. In contrast, hemodialysis was associated with decreased aortic PWV independent of renal failure and the other factors. Further analyses in the combined uremic patients again indicated the favorable impact of hemodialysis on aortic PWV independent of the classical risk factors, use of antihypertensive medications, including angiotensin-converting enzyme inhibitors and calcium channel blockers, hematocrit, serum calcium, phosphorus, parathyroid hormone levels, and the use of calcium carbonate. Insulin resistance using homeostasis model assessment (HOMA-IR) was associated with increased aortic PWV. CONCLUSION: Aortic stiffening was present in uremic patients before starting hemodialysis treatment and no adverse effect of hemodialysis was observed, suggesting the important roles of renal failure and/or metabolic alterations secondary to renal failure in arterial stiffness in patients with uremia.  相似文献   
47.
A 41-year-old man presented with progressive worsening of postural headache. Computed tomography (CT) showed bilateral subdural hematomas without prior history of trauma. The diagnosis was spontaneous intracranial hypotension (SIH). Conservative treatment with oral steroids failed to prevent gradual deterioration of the patient's consciousness. CT myelography revealed massive cerebrospinal fluid (CSF) leakage between the C-1 and C-2 levels. The leak was repaired surgically via a laminectomy. A cyst, thought to be a meningeal cyst, was discovered adjacent to the right C-2 nerve root, and CSF was seen seeping out from around the cyst after a Valsalva maneuver. The presumed dural defect of the cyst was sealed by packing with muscle fragments and fibrin glue. The symptoms disappeared soon after surgery. He was discharged 1 month after surgery without deficits. Most SIH cases are benign and can be managed conservatively, or by the epidural blood patch method. Surgery is more invasive than the epidural blood patch method, but should be performed in patients with a high cervical lesion and massive CSF leakage.  相似文献   
48.
Many approaches for resection of the superior mediastinal tumors have been reported. We introduce an approach, which we call the cervical anterior approach. This approach is only cervical and does not require a sternotomy. Merits of this approach include the ability to remove the tumor without opening the mediastinal or parietal pleura, as well as obviating draining the thoracic cavity. The tumor is also directly visible, and the surgeon can avoid injury to the great vessels. This approach is recommended when the tumor is located superior to the third thoracic vertebra level, when it borders the great vessels, and when it does not border the trunk of the brachial plexus or nerve root. This approach is easy and safe for surgical procedures.  相似文献   
49.
50.
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