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   30511篇
  免费   1744篇
  国内免费   268篇
耳鼻咽喉   268篇
儿科学   618篇
妇产科学   631篇
基础医学   3143篇
口腔科学   708篇
临床医学   2274篇
内科学   8682篇
皮肤病学   408篇
神经病学   2718篇
特种医学   1127篇
外科学   5493篇
综合类   71篇
一般理论   7篇
预防医学   1231篇
眼科学   569篇
药学   1791篇
中国医学   69篇
肿瘤学   2715篇
  2024年   24篇
  2023年   281篇
  2022年   515篇
  2021年   1067篇
  2020年   616篇
  2019年   873篇
  2018年   1059篇
  2017年   771篇
  2016年   929篇
  2015年   946篇
  2014年   1281篇
  2013年   1593篇
  2012年   2419篇
  2011年   2311篇
  2010年   1318篇
  2009年   1273篇
  2008年   2025篇
  2007年   1973篇
  2006年   1859篇
  2005年   1809篇
  2004年   1705篇
  2003年   1478篇
  2002年   1329篇
  2001年   235篇
  2000年   233篇
  1999年   254篇
  1998年   241篇
  1997年   202篇
  1996年   183篇
  1995年   179篇
  1994年   154篇
  1993年   136篇
  1992年   137篇
  1991年   106篇
  1990年   105篇
  1989年   87篇
  1988年   94篇
  1987年   73篇
  1986年   73篇
  1985年   58篇
  1984年   56篇
  1983年   46篇
  1982年   58篇
  1981年   37篇
  1980年   32篇
  1979年   45篇
  1978年   24篇
  1976年   15篇
  1974年   22篇
  1969年   16篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
91.
The incidence of invasive fungal infection is increasing especially in the field of transplantation, affecting as many as 50% of bone marrow transplant (BMT) patients with neutropenia and 5-20% of solid-organ transplant (SOT) recipients. Fusarium species are soil saprophytes and plant pathogens. They may cause superficial mycoses or important opportunistic infections in patients with bone marrow suppression and neutropenia, they have been rarely described in solid organ recipients, and up to now there have been no reports of such infection in isolated liver transplanted patients. We describe a case of disseminated Fusarium solani infection with hepatic localization in a liver transplanted patient that resolved with the administration of amphotericin B. Our observation confirms that Fusarium spp. are emerging pathogens that may most frequently affect not only BMT patients and patients with hematological malignancies, but also SOT patients. They may cause both localized and disseminated infection. In conclusion, Fusarium spp. etiology should be considered in the context of infectious diseases following liver transplantation.  相似文献   
92.
The present study reviews the literature concerning the surgical treatment of Aspergillus mycetoma (AM) in the last 20 years to identify a gold standard surgical technique. Aspergillus mycetoma of the maxillary sinus, or mycetoma (fungus ball), is a noninvasive or extramucosal mycotic infection. Surgical removal of the sinus fungal masses to ensure drainage and aeration is performed using the traditional Caldwell-Luc (CL) procedure or endoscopic sinus surgery (ESS). Results of this review suggest that the gold standard surgical technique for AM is ESS with middle meatal antrostomy. General or local antifungal drugs are not indicated. Combined approach with an intraoral surgical access from the anterolateral wall of the maxillary sinus has to be reserved for selected cases in which ESS doesn't permit complete extraction of all fungal concretions or foreign bodies. The CL procedure should be avoided, because it has detrimental consequences for sinus physiology.  相似文献   
93.
BACKGROUND: Nonsteroidal anti-inflammatory drugs and opioids are routinely used after cardiac surgery in order to mitigate postoperative pain; however, these drugs are burdened by side effects. Tramadol and paracetamol are believed to be lacking in such side effects. The aim of this study was to examine the efficacy of intravenous paracetamol as an adjunctive analgesic to a tramadol-based background analgesia after cardiac surgery. METHODS: A total of 113 patients participated in this single center, placebo-controlled, double-blind, randomized trial. Fifty-six patients were randomized to receive paracetamol and 57 to placebo. Intravenous study drug (1 g) was administered 15 min before the end of surgery and every 6h for 72 h. Standard analgesia (tramadol) and anti-emetic prophylactic regimen (ondansetron) were available to both patient groups. Postoperative pain was evaluated by visual analog scale, and it was measured at rest and during a deep breath. A rescue dose of 2-5 mg of intravenous morphine was administered whenever the VAS score was greater than 3. RESULTS: Baseline characteristics were equivalent between the two groups. At 12, 18, 24 h after the end of operation, patients who received paracetamol had significantly less pain at rest (p=0.0041, 0.0039, 0.0044, respectively); after this time the two groups did not differ. During a deep breath the difference was significant only at 12 h (p=0.0040). Paracetamol group required less cumulative morphine than placebo group (48 mg vs 97 mg) even if the difference did not reach statistical significance (p=0.274). CONCLUSIONS: In patients undergoing cardiac surgery, intravenous paracetamol in combination with tramadol provides effective pain control.  相似文献   
94.
Altered dimerization of metabotropic glutamate receptor 3 in schizophrenia.   总被引:1,自引:0,他引:1  
BACKGROUND: Metabotropic glutamate receptors (mGlus) may be involved in the pathophysiology of schizophrenia. Group II mGlus (mGlu2 and mGlu3) have attracted considerable interest since the development of potent specific agonists that exhibit atypical antipsychotic-like activity and reports of a genetic association between the mGlu3 gene and schizophrenia. METHODS: In this postmortem study, mGlu3 protein levels in Brodmann area 10 of prefrontal cortex from schizophrenic (n = 20) and control (n = 35) subjects were analyzed by western immunoblotting using a novel specific mGlu3 antibody and an antibody for the vesicular glutamate transporter 1 (VGluT1). RESULTS: We report a significant decrease in the dimeric/oligomeric forms of mGlu3 in schizophrenic patients compared with control subjects, whereas total mGlu3 and VGluT1 levels were not altered significantly. CONCLUSIONS: This is the first experimental evidence that mGlu3 receptor levels are altered in schizophrenia and supports the hypothesis that neurotransmission involving this particular excitatory amino acid receptor is impaired in schizophrenia.  相似文献   
95.
Authors' reply     
  相似文献   
96.
Background: Measuring the work of breathing of patients undergoing spontaneous assisted ventilation can be useful to monitor and titrate ventilatory support. The aim of this study was to obtain measurements of the pressure generated by the respiratory muscles (PMUSC) and the derived pressure-time product (PTP; a good indicator of the metabolic work of breathing), performing the rapid interrupter technique with a commercial ventilator.

Methods: A Draeger Evita 4 ventilator (Draeger Medical, Lubeck, Germany) was controlled by a personal computer to rapidly interrupt the airway flow at different times and volumes of the respiratory cycle during pressure-support ventilation. From the airway pressure tracing after the occlusion, the authors estimated the alveolar pressure and PMUSC; the integration of PMUSC values over the inspiratory time yields the measurement of PTP. Esophageal pressure measurements were used as a reference. After a bench study of the valves' performance, the authors performed 11 measurement sequences in eight patients.

Results: The closure times for the inspiratory and expiratory valves were 74 +/- 10 and 61 +/- 13 ms, respectively. The interrupter technique provided a reliable estimate of PMUSC (PMUSC, occl = 1.00 [middle dot] PMUSC, pes + 0.19; r = 0.88; 95% confidence interval for agreement, +5.49/-5.32 cm H2O). PTPoccl tightly correlated with PTPpes (PTPoccl = 0.95 [middle dot] PTPpes + 0.13; r = 0.96; 95% confidence interval, 1.94/-1.61 cm H2O [middle dot] s).  相似文献   

97.
Support vector machines (SVMs) are a powerful technique developed in the last decade to effectively tackle classification and regression problems. In this paper we describe how support vector machines and artificial neural networks can be integrated in order to classify objects correctly. This technique has been successfully applied to the problem of determining the quality of tiles. Using an optical reader system, some features are automatically extracted, then a subset of the features is determined and the tiles are classified based on this subset.  相似文献   
98.
Abstract The aim of this study was to evaluate the short- to medium-term results (up to 2 years) of conservative and surgical treatments of patients with symptomatic lumbar stenosis. To our knowledge, no previous study has provided strict indications for conservative or surgical treatment. We retrospectively studied 184 patients, who were divided into 3 groups according to JOA (Japanese Orthopaedic Association) score. A cutoff JOA score was arbitrarily fixed at 7. Patients with a score ≤7 (n=12; group A) underwent surgery, while patients with a score >7 (n=172) were conservatively treated. Group A included patients surgically treated within two months from diagnosis. Group B consisted of 144 patients who received conservative treatment, while group C (28 patients) represented patients who underwent surgery after a period of failed conservative treatment. The outcomes of surgical and conservative treatments were evaluated after 12 and 24 months, and were rated as satisfactory, not totally satisfactory, not satisfactory or totally unsatisfactory. Conservative treatment consisted of physical, orthotic and drug therapy, whereas surgical treatment included spinal decompression and instrumentation (if indicated), either rigidly or dynamically performed. Surgery was indicated in 22% of all patients and we obtained excellent results in 85% of them. Operative treatment provides excellent results for patients with severe clinical presentation (JOA score ≤7), while individuals with mild to moderate spinal stenosis (JOA score >7) should receive conservative treatment.  相似文献   
99.
Tibial plateau fractures are complex injuries which, if not adequately treated, can lead to invalidating sequelae. They constitute on average about 1% of all fractures, and up to 8% in patients over 65 years, and can be caused by both high- and low-energy trauma. Unlike in younger subjects, treatment of tibial plateau fractures in the elderly is not univocal and depends on the patient’s functional needs, bone quality and systemic comorbidities. In this retrospective study, 49 patients with a mean age of 72 years, who underwent surgical treatment of a tibial plateau fracture, were assessed by the Rasmussen’s clinical and radiological grading systems. Clinical and radiographic outcomes were satisfactory in 75.5 and 59.1% of cases, respectively. Data were also analyzed, in terms of fracture type, age and gender, to detect any statistically significant correlation between these parameters and clinical and radiographic outcomes.  相似文献   
100.
Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is mainly observed in patients with multiple myeloma and bone metastasis from solid tumors receiving iv bisphosphonate therapy. The reported incidence of BRONJ is significantly higher with the iv preparations zoledronic acid and pamidronate while the risk appears to be minimal for patients receiving oral bisphosphonates. Currently available published incidence data for BRONJ are based on retrospective studies and estimates of cumulative incidence range from 0.8 to 12%. The mandible is more commonly affected than the maxilla (2:1 ratio), and 60–70% of cases are preceded by a dental surgical procedure. The signs and symptoms that may occur before the appearance of clinical evident osteonecrosis include changes in the health of periodontal tissues, non-healing mucosal ulcers, loose teeth and unexplained soft-tissue infection. Although the definitive role of bisphosphonates remains to be elucidated, the inhibition of physiologic bone remodeling and angiogenesis by these potent drugs impairs the regenerative capacity of the bone causing the development of BRONJ. Tooth extraction as a precipitating event is a common observation. The significant benefits that bisphosphonates offer to patients clearly surpass the risk of potential side effects; however, any patient for whom prolonged bisphosphonate therapy is indicated, should be provided with preventive dental care in order to minimize the risk of developing this severe condition. This article provides an update review of current knowledge about clinical, pathological and management aspects of BRONJ.  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