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   2704篇
  免费   236篇
  国内免费   14篇
耳鼻咽喉   13篇
儿科学   195篇
妇产科学   59篇
基础医学   282篇
口腔科学   59篇
临床医学   248篇
内科学   698篇
皮肤病学   21篇
神经病学   234篇
特种医学   144篇
外科学   438篇
综合类   79篇
预防医学   200篇
眼科学   48篇
药学   144篇
中国医学   3篇
肿瘤学   89篇
  2021年   34篇
  2019年   34篇
  2018年   31篇
  2017年   27篇
  2016年   31篇
  2015年   37篇
  2014年   47篇
  2013年   74篇
  2012年   75篇
  2011年   87篇
  2010年   45篇
  2009年   71篇
  2008年   106篇
  2007年   119篇
  2006年   94篇
  2005年   94篇
  2004年   102篇
  2003年   87篇
  2002年   87篇
  2001年   81篇
  2000年   87篇
  1999年   87篇
  1998年   49篇
  1996年   31篇
  1995年   30篇
  1994年   28篇
  1993年   28篇
  1992年   70篇
  1991年   97篇
  1990年   74篇
  1989年   76篇
  1988年   61篇
  1987年   67篇
  1986年   72篇
  1985年   70篇
  1984年   45篇
  1983年   43篇
  1982年   29篇
  1981年   32篇
  1980年   33篇
  1979年   41篇
  1978年   32篇
  1977年   25篇
  1976年   25篇
  1975年   30篇
  1974年   29篇
  1973年   41篇
  1972年   33篇
  1970年   29篇
  1969年   27篇
排序方式: 共有2954条查询结果,搜索用时 15 毫秒
81.
As a result of experimental data and favorable clinical impressions, the pneumatic antishock garment (PASG) has gained widespread acceptance as a reasonable standard of care in emergency medical services (EMS) systems. It is currently legislated as required equipment for medical rescue vehicles in two-thirds of the United States. But despite a decade of widespread use, prospective, randomized, controlled trials that demonstrate the efficacy of the PASG have not been published. Furthermore, certain complications have been reported and concerns have been raised about the use of the PASG under certain circumstances, such as penetrating thoracic injury. In the fall of 1983, the City of Houston EMS system embarked on a long-term prospective evaluation of PASG use in hypotensive victims of injury in the urban prehospital setting. All victims of injury whose systolic blood pressure was 90 mm Hg or less when they initially presented to paramedics in the field were entered into the study. All patients received the identical treatment protocol, with the sole exception of PASG application and inflation to full pressure prior to intravenous catheterization on an alternate day basis. Prospectively collected demographic data have demonstrated that the two resulting groups of PASG and no-PASG patients are well matched in terms of age, sex, injury type, anatomic location of the injury, initial field trauma score, injury severity score and probabilities of survival, as well as the amounts of IV fluids infused in the prehospital setting and the response, scene, and transport times.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
82.
Criteria for the classification of juvenile rheumatoid arthritis were analyzed in a detailed database of 250 children in order to assess the accuracy of diagnosis and validity of onset types and course subtypes. A number of conclusions have been derived from this study: All definitions of the 1973 criteria for classification of juvenile rheumatoid arthritis should be retained. The addition of onset types to the 1976 revision of the criteria has been validated. The course of the disease after the onset period of 6 months is as important to the outcome of a group of children as is the onset type. The current classification should be broadened to include the course subtypes.  相似文献   
83.
We evaluated the effect of chronic bovine growth hormone treatment on the hepatic somatotropic receptor. Growing lambs were treated with bGH at 0, 0.05, 0.15, 0.25 or 0.55 mg.kg-1.day-1 daily (N = 5/group) for 56 days. The binding of ovine GH to hepatic membranes washed with 4 mol/l MgCl2 and prepared in the presence of aprotinin was examined. The specific binding of oGH was increased (p less than 0.01) from 7.1 +/- 1.2% in saline-treated controls to 17.4 +/- 1.5% in the 0.55 mg.kg-1.day-1 group. Scatchard analysis showed curvilinear plots that best fitted a two-site model in 22/25 livers. The two sites had estimated dissociation constants (Kd) of 3 to 13 nmol/l for the low-affinity site and a Kd ranging from 0.17 to 0.31 nmol/l for the high-affinity site. Treatment with bGH had no consistent effect on the affinity of either binding site. However, bGH therapy was associated with a dose-dependent increase (p less than 0.01) in the number of high-affinity somatotropic receptors. There was no effect of bGH therapy on the concentration of low-affinity binding sites. The concentration of high-affinity receptors correlated with weight gain (r = 0.54, p less than 0.01), fat content (r = -0.54, p less than 0.01), protein content (r = 0.40, p less than 0.05), and plasma IGF-I (r = 0.57, p less than 0.005). The concentrations of low-affinity binding sites showed no such correlations.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
84.
Objectives: To evaluate all complications that occurred during or after cardiac catheterizations for Amplatzer PFO device closure of patent foramen ovale (PFO), determine the cause of the complications and recommend techniques to minimize complications in the future. Background: Rare complications were reported to the manufacturer of the Amplatzer PFO occluder since the introduction of the device. Methods: A panel of independent physicians reviewed all complications reported to the manufacturer to determine whether the complication was related to the device or related to the cardiac catheterization procedure. Demographic data, echocardiograms, operative reports, and time to occurrence of complications were reviewed. Results: A total of 11 events were reported. Only two patients had device related complications (erosion), an incidence of 0.018%. Two patients were found to have additional atrial septal defect after PFO closure. Two patients were thought to have an inflammatory reaction without any serious sequelae. Five complications were related to the cardiac catheterization procedure (atrial appendage perforation). Conclusions: Device related complications after Amplatzer PFO occluder placement are extremely rare. Cardiac catheterization related complications appear to be the most common cause of the hemodynamic compromise. Careful manipulation of catheters and wires, recognition of the location of the catheter by fluoroscopy and echocardiography will decrease the risk of such complications. © 2008 Wiley‐Liss, Inc.  相似文献   
85.
Bass J  White DA 《Chest》2005,127(6):2101-2105
BACKGROUND: Pleural effusions occur in patients with hematologic malignancies, particularly during periods of hospitalization. Thoracentesis is often performed to diagnose infection and to exclude the presence of complicated parapneumonic effusions. The efficacy and safety of thoracentesis in this setting has not been well-studied. DESIGN: Retrospective chart review of hospitalized patients with hematologic malignancies undergoing thoracentesis. The aim of this study was to assess the role of thoracentesis in establishing a diagnosis of infection in this population and to determine the risk of complications. RESULTS: A total of 100 thoracentesis findings were analyzed in patients with lymphoma (52 patients) and leukemia (27 patients), and in patients who had undergone bone marrow or stem cell transplantation (21 patients). The indication for performing thoracentesis was to exclude infection in 69% of cases. Fever was present in 59% of the patients, and a concomitant lung parenchymal abnormality was present in 69% of cases. Effusions were moderate to large in size (87% of cases), and were both bilateral (62%) and unilateral (38%). Exudates were documented in 83%of the cases. A specific diagnosis was found in 21 patients and was more frequently established in those with lymphoma (31%) compared to the other groups of patients. Diagnoses found included malignancy in 14 cases, chylous effusions in 6 cases, and infection in 1 case. The one patient in whom empyema was found required drainage. The criteria for a parapneumonic effusion were not found in any other patients. The complication rate of 9% (pneumothorax, seven patients; hemothorax, two patients) was comparable to that in other populations of patients. CONCLUSIONS: Despite a high propensity for developing pulmonary infections, hospitalized patients with hematologic malignancies rarely developed complex parapneumonic effusions. The etiology of many of the effusions that occurred in this setting was unclear.  相似文献   
86.
425 patients with pulmonary emboli at post mortem were studied retrospectively with the main focus on the clinical diagnosis. The diagnosis of pulmonary embolus was made or suspected while the patient was still alive in 59 patients (14%) and was first written in the post mortem request form in 130 patients (30%). In 236 patients (56%) the diagnosis was made only at post mortem. Even in fatal emboli the diagnosis was missed in 43% of cases. A multiplicity of non specific symptoms and signs was observed with a minority of patients showing signs and symptoms considered as typical. Of 231 thrombophlebitis processes found in locations which could give rise to clinical symptoms in the lower extremities the diagnosis was noted only in 25 cases. Chest x-ray and ECG were negative in two thirds of the cases. The high rate of misdiagnosis derived from two reasons: (a) subjective factors: lack of awareness; (b) objective difficulties: lack of specificity of clinical symptoms and signs as well as of results of the routine tests (chest x-ray and ECG). Since sophisticated confirmative tests for pulmonary emboli will be performed only on the basis of clinical suspicion, clinical awareness based on the observations detailed in this survey is still the cornerstone of diagnosis.  相似文献   
87.
Parameterization of the ST-segment is used as a tool for risk stratification for patients to suffer from ventricular tachycardia. This parameterization is performed in terms of Principal Component Analysis (PCA) applied on multichannel magnetocardiographic (MCG) recordings. 55-channel MCG was recorded from 14 normal persons, 10 patients with CHD, 14 patients with MI, and six patients with VT. We found a significantly (p?<?0.05) lower PCA-score in patients with MI compared to normals. The lowest PCA-score was found in VT patients. Significant differences can be found between VT patients and normals and also between VT patients and CHD patients.  相似文献   
88.
89.
Two B-cell lines, 2F7 and 10C9, were established by single cell cloning from biopsies obtained from two acquired immune deficiency syndrome patients with Burkitt's lymphoma. Representation of the original tumors was verified by demonstration of (1) identical biallelic rearrangement of Ig genes for 2F7 and (2) shared idiotype for 10C9. Both cell lines displayed cell-surface Ig and secreted Ig (IgM lambda for 2F7, IgM kappa for 10C9). IgMs from both cell lines immunoprecipitated actin; in addition, 2F7 IgM lambda immunoprecipitated recombinant human immunodeficiency virus type 1 (HIV-1) gp 160. 2F7 IgM lambda did not react with other autoantigens (double-stranded and single-stranded DNA, actin, bovine serum albumin, IgG), whereas 10C9 IgM kappa reacted with human IgG. The 2F7 IgM heavy-chain variable region (VH) showed a 95% nucleotide homology with a previously sequenced VHIII germline gene, hv3019b9, whereas the 10C9 IgM VH showed a 95% homology with a previously sequenced VHIV germline gene, VH4.21. Use of minimally modified VH genes and demonstration of reactivity with chronically present antigens (ie, actin, HIV-1 gp 160, or human IgG) suggests that B cells in HIV-1-infected individuals proliferating in response to chronic antigenic stimulation may be at increased risk for lymphomagenesis.  相似文献   
90.
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