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   3054篇
  免费   263篇
  国内免费   12篇
耳鼻咽喉   127篇
儿科学   218篇
妇产科学   93篇
基础医学   348篇
口腔科学   60篇
临床医学   324篇
内科学   680篇
皮肤病学   70篇
神经病学   186篇
特种医学   283篇
外科学   367篇
综合类   157篇
一般理论   5篇
预防医学   197篇
眼科学   30篇
药学   109篇
中国医学   11篇
肿瘤学   64篇
  2021年   34篇
  2020年   19篇
  2019年   40篇
  2018年   44篇
  2017年   36篇
  2016年   26篇
  2015年   35篇
  2014年   79篇
  2013年   108篇
  2012年   109篇
  2011年   135篇
  2010年   91篇
  2009年   104篇
  2008年   102篇
  2007年   122篇
  2006年   107篇
  2005年   88篇
  2004年   73篇
  2003年   55篇
  2002年   69篇
  2001年   74篇
  2000年   88篇
  1999年   48篇
  1998年   100篇
  1997年   68篇
  1996年   80篇
  1995年   71篇
  1994年   72篇
  1993年   64篇
  1992年   85篇
  1991年   77篇
  1990年   73篇
  1989年   99篇
  1988年   78篇
  1987年   65篇
  1986年   71篇
  1985年   71篇
  1984年   70篇
  1983年   34篇
  1982年   28篇
  1981年   32篇
  1980年   31篇
  1979年   47篇
  1978年   27篇
  1977年   28篇
  1976年   23篇
  1975年   30篇
  1973年   30篇
  1972年   22篇
  1971年   24篇
排序方式: 共有3329条查询结果,搜索用时 31 毫秒
1.
Epidermolysis bullosa simplex (EBS) is a skin fragility disorder resulting from mutations of structural proteins in the epidermis. We provide a brief report of long‐term survival and reproduction in a mother with EBS due to keratin 5 (KRT5) c.1429G > A (p.E477K) mutation, which causes a particularly severe form of the disease.  相似文献   
2.
Aims: Studies conducted in first‐episode psychosis (FEP) samples avoid many biases. However, very few studies are based on epidemiological cohorts treated in specialized FEP services. The aim of this file audit study was to examine premorbid and baseline characteristics of a large epidemiological sample of FEP. Methods: File audit study of all patients admitted to the Early Psychosis Prevention and Intervention Centre between 1998 and 2000 using a specialized questionnaire. Results: There were 661 patient files included in the study. Premorbid evaluation revealed high rates of substance use disorder (74.1%), history of psychiatric disorder (47.5%), past traumatic events (82.7%) suicide attempts (14.3%) and family history of psychiatric illness (55.6%). Baseline characteristics revealed high intensity of illness (mean CGI 5.5), high prevalence of lack of insight (62%) and high rate of comorbidity (70%). Conclusion: High rates of traumatic events or episodes of mental illness before treatment for FEP must be considered when designing treatment approaches because a too narrow focus on positive psychotic symptoms will inevitably lead to incomplete treatment. Additionally, early intervention programmes need sufficient range of resources to address the multiple challenges presented by FEP patients such as high severity of illness, comorbidities and functional impairment. Finally, observation of an important degree of functional impairment despite short duration of untreated psychosis suggests that while early detection of FEP is a necessary step in early intervention, it may not be sufficient to improve functional recovery in psychosis and that efforts aimed at identifying people during the prodromal phase of psychotic disorders should be pursued.  相似文献   
3.
AIM: Peritonectomy procedures with intraperitoneal chemohyperthermia are an effective but costly treatment for peritoneal carcinomatosis (PC). Consequently a proper selection of patients is necessary. We evaluated the benefit of MRI prior to surgery, in the detection of two of the main surgery contraindications: bulky mesenteric tumors and bladder implants. METHODS: Three experts retrospectively reviewed abdominal and pelvic MRI from 19 cases of surgically proved PC (ovary: 7; colorectal: 7; gastric: 2; pseudomyxoma peritonei: 2; appendix: 1). RESULTS: Mesenteric tumors were always identified as hypersignal masses on axial and coronal fat suppression gadolinium-enhanced T1 images (n=3). Three out of five bladder implants were detected. The two cases of bladder implants that were not detected on MRI were missed because the bladder was not filled. The best sequence for the detection of bladder involvement was axial T2-weighted images with bladder filling. CONCLUSIONS: Evaluating the preoperative resectability of PC is crucial for patient management. MRI seems to reliably detect bulky mesenteric tumors and bladder implants on condition the bladder is filled and appropriate sequences are used.  相似文献   
4.
目的 探讨创伤后迟发性脑肿胀的临床特点、发病机制与治疗。方法 回顾性分析1998年1月~2005年6月年收治的17例迟发性脑肿胀患者的临床特点和救治情况。结果 所有颅脑损伤患者采用保守治疗后均有好转,但于伤后5-10d出现恶化,CT复查有脑肿胀,经加强综合脱水等治疗后16例治愈,1例死亡。结论 迟发性脑肿胀好发于对冲性额、颞叶挫裂伤伴明显蛛网膜下腔出血、硬膜下薄层血肿及早期CT有脑肿胀者。其发病机制可能与创伤后的迟发性脑血管痉挛、微循环障碍、静脉回流障碍及甘露醇作用下降等因素有关。此类患者病情隐蔽性强,应加强观察、积极行CT复查,如能早期明确诊断,保守治疗多数效果良好。  相似文献   
5.
Numerous techniques for the surgical management of laryngotracheal stenosis in children have been described in the literature. These surgical modalities include endoscopic management and open laryngotracheal reconstruction using costal cartilage grafts for expansion of the stenotic subglottic region. Although tracheal resection with primary reanastomosis for the management of tracheal stenosis is reported frequently in the adult population, children rarely have stenotic lesions that are amenable to this particular technique. Laryngotracheal stenosis in children most commonly involves the subglottis. This makes tracheal resection with anastomosis technically difficult to perform, due to the close proximity of the vocal cords. We have found a subpopulation of children at our institution with high tracheal stenoses, with minimal lower subglottic involvement, who were amenable to tracheal resection with primary anastomosis. We review our experience with this technique. The indications for this surgical modality in children are discussed, as well as the surgical technique.  相似文献   
6.
OBJECTIVE. We performed a study to determine if the appearance of the pancreatic duct on ERCP before and after placement of pancreatic duct stents correlates with the therapeutic response in patients treated for impaired pancreatic drainage. MATERIALS AND METHODS. Findings in 29 consecutive patients with a variety of benign pancreatic diseases in whom pancreatic stents were placed and subsequently removed within a 3-year period were reviewed retrospectively. Early (1-5 days) and late (1-3 months) clinical outcomes after stent placement were assessed. These findings were correlated with a blinded interpretation of ERCP findings (Cambridge criteria were used) before and after stent placement. RESULTS. ERCP findings before stent placement were normal in 10 patients. At the end of stent therapy, ERCP showed changes associated with chronic pancreatitis in all 10; five had focal narrowing at the tip of the stent. Subsequent ERCP studies in five of these 10 patients showed that ductal changes induced by stents diminished after stent removal. Of the 19 patients with abnormal findings on ERCP at the time of stent placement, ERCP at the end of stent therapy showed some improvement in seven patients, no change in eight, and deterioration in four. Changes seen on ERCP had no statistically significant correlation with clinical outcome (p = .36). CONCLUSION. Our findings show that pancreatic duct stents can induce abnormalities on ERCP indicative of chronic pancreatitis. However, diminution of these abnormalities after stent removal in some patients suggests that these changes may be due to edema rather than to fibrosis. Ductal changes seen on ERCP are not a useful guide for determining the degree of response to pancreatic stents.  相似文献   
7.
8.
Prediction of hemorrhagic transformation (HT) in patients treated by intravenous recombinant tissue-type plasminogen activator (rt-PA) is a challenging issue in acute stroke management. HT may be correlated with severe hypoperfusion. Signal changes may be observed at susceptibility-weighted magnetic resonance imaging (MRI) within large perfusion defects. A signal drop within cerebral veins at T2*-weighted gradient-echo MRI may be expected in severe ischemia, and may indicate subsequent risk of HT. The authors prospectively searched for an abnormal visibility of transcerebral veins (AVV) within the ischemic area in patients with hemispheric ischemic stroke, before they were treated with intravenous rt-PA therapy. Any correlation between AVV and baseline clinical or MRI findings, or further HT, was noted. An AVV was present in 23 of 49 patients (obvious, n = 8; moderate, n = 15), and was supported by severe hemodynamic changes at baseline MRI. The AVV was correlated with the occurrence of parenchymal hematoma type 2 at computed tomography during the first week (r = 0.44, P = 0.002). Five of six type 2 parenchymal hematomas occurred in association with obvious AVV. At multiple regression analysis, two baseline MRI factors had an independent predictive value for HT risk during the first week: the AVV and the cerebral blood volume ratio (Nagelkerke R2 = 0.48).  相似文献   
9.
Retrorenal colon: implications for percutaneous diskectomy   总被引:1,自引:0,他引:1  
Helms  CA; Munk  PL; Witt  WS; Davis  GW; Morris  J; Onik  G 《Radiology》1989,171(3):864-865
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary.  相似文献   
10.
The results of conventional cerebrospinal fluid (CSF) investigations (CSF cell count, protein and glucose concentrations and Pandy's test for CSF globulin) obtained on admission and sequentially from weekly follow-up lumbar punctures for 4 weeks were evaluated in 99 children (median age 28 months) with stage II (50 children) and stage III (49 children) tuberculous meningitis. On admission, six children (6%) had a CSF cell count greater than 500 x 10(6)/l and nine (9%) a polymorphonuclear predominance. A CSF protein less than 0.8 g/l was found in 17 children (18%) of 97 in whom CSF protein was evaluated. Globulin was either absent or present as a trace only in 26 children (27%). CSF glucose was less than 2.2 mmol/l in 58 cases (60%) and less than 2.5 mmol/l in 67 (69%). In 63 children weekly CSF specimens obtained for the 1st 4 weeks of therapy showed an uninterrupted decline in cell count in 23 (37%), a fluctuating downward trend in 27 (43%) and a fluctuating upward trend in 13 (21%). Sequential CSF protein values in 57 children showed an uninterrupted rise in three (5%), a fluctuating upward course in 19 (33%), an uninterrupted downward trend in seven (12%), and a fluctuating downward course in 28 (49%). Of the 61 children in whom sequential CSF glucose concentrations were available, 11 (18%) experienced fluctuating concentrations, values falling to less than 2.2 mmol/l after being greater than 2.2 mmol/l on admission or after having risen to greater than 2.2 mmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)  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