全文获取类型
收费全文 | 1462548篇 |
免费 | 122828篇 |
国内免费 | 9854篇 |
专业分类
耳鼻咽喉 | 18235篇 |
儿科学 | 45781篇 |
妇产科学 | 40231篇 |
基础医学 | 201803篇 |
口腔科学 | 39790篇 |
临床医学 | 132779篇 |
内科学 | 299656篇 |
皮肤病学 | 34057篇 |
神经病学 | 118410篇 |
特种医学 | 59708篇 |
外国民族医学 | 297篇 |
外科学 | 226462篇 |
综合类 | 41193篇 |
现状与发展 | 7篇 |
一般理论 | 449篇 |
预防医学 | 115708篇 |
眼科学 | 31615篇 |
药学 | 105505篇 |
31篇 | |
中国医学 | 4775篇 |
肿瘤学 | 78738篇 |
出版年
2018年 | 15711篇 |
2017年 | 12668篇 |
2016年 | 14678篇 |
2015年 | 16922篇 |
2014年 | 23207篇 |
2013年 | 33146篇 |
2012年 | 41191篇 |
2011年 | 44366篇 |
2010年 | 27649篇 |
2009年 | 26677篇 |
2008年 | 40509篇 |
2007年 | 43121篇 |
2006年 | 44276篇 |
2005年 | 42718篇 |
2004年 | 40076篇 |
2003年 | 38851篇 |
2002年 | 36667篇 |
2001年 | 71632篇 |
2000年 | 73615篇 |
1999年 | 61591篇 |
1998年 | 18716篇 |
1997年 | 16601篇 |
1996年 | 17099篇 |
1995年 | 17229篇 |
1994年 | 16005篇 |
1993年 | 14946篇 |
1992年 | 50269篇 |
1991年 | 48951篇 |
1990年 | 46893篇 |
1989年 | 44755篇 |
1988年 | 41617篇 |
1987年 | 40827篇 |
1986年 | 38429篇 |
1985年 | 37138篇 |
1984年 | 28065篇 |
1983年 | 23611篇 |
1982年 | 14670篇 |
1981年 | 13141篇 |
1980年 | 12365篇 |
1979年 | 25169篇 |
1978年 | 18049篇 |
1977年 | 15208篇 |
1976年 | 13980篇 |
1975年 | 14776篇 |
1974年 | 17294篇 |
1973年 | 16644篇 |
1972年 | 15402篇 |
1971年 | 14173篇 |
1970年 | 12899篇 |
1969年 | 12119篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Aetiology and outcome of severe community-acquired pneumonia in children admitted to a paediatric intensive care unit. 总被引:1,自引:0,他引:1
OBJECTIVE: To determine the aetiological agents and outcome of severe community-acquired pneumonia (SCAP) in children admitted to the paediatric intensive care unit (PICU) at Kalafong Hospital, Pretoria. PATIENTS AND METHODS: An audit was done after a protocol was implemented to identify the aetiological agents in children with life-threatening SCAP admitted to the PICU from the emergency room. The following investigations were done as per protocol: blood culture, culture of the tracheal aspirate, immunofluorescence and culture of the nasopharyngeal aspirate, microscopy and culture of the gastric juice for Mycobacterium tuberculosis, and determination of HIV status. The following data, documented prospectively, were obtained from patient records: date of admission, age, gender, weight, duration of ventilation, duration of stay in the PICU, survival or death, and severity of illness as determined by means of the score for acute neonatal physiology (SNAP) or paediatric risk of mortality (PRISM) score depending on the child's age. RESULTS: Twenty-three children were admitted over a 1-year period (1 November 1994-30 October 1995). Their median age was 10 weeks (range 2 weeks-5 years) and the sex distribution was equal. Two children were HIV-infected. Twenty children received mechanical ventilation for a median period of 6.5 days (range 2-16 days). Aetiological agents were identified in 15/23 children (65%). Respiratory syncytial virus (RSV) was the most common pathogen, identified in 7/23 children, Klebsiella pneumoniae was the most common bacterial pathogen, identified in 5 children (2 blood cultures and 3 tracheal aspirates). Tuberculosis was not diagnosed. The mean PRISM score was similar in survivors and children who died. The case fatality rate was 30%. The 7 children who died had a median arterial oxygen tension/fraction of inspired oxygen (PaO2/FiO2) ratio of 94 (range 32-111) and the 16 survivors had a median ratio of 146 (range 51-252) (P = 0.01) on admission. Both HIV-infected children died and postmortem examination showed a pneumonia due to Pneumocystis carinii and cytomegalovirus. CONCLUSIONS: SCAP occurs in very young children. One or more pathogens were isolated in 65% of cases. Viral pathogens predominated, with RSV being the most common. The yield of positive blood cultures was low at 17%. Streptococcus pneumoniae and Haemophilus influenzae were not found. The case fatality rate was 30% and death was more likely with a low PaO2/FiO2 ratio on admission. 相似文献
972.
OBJECTIVE: To study the antibacterial activity of Chinese medicine kou-Kang mouthwash and its acute toxicity, and provide the basis of experiment and therapy for infectious diseases of the oral cavity. METHODS: Minimal inhibitory concentrations (MIC) of kou-Kang mouthwash were determined by the agar dilution method, and the acute toxicity was done. RESULTS: The range of MIC kou-Kang mouthwash against 27 Gram negative bacterial were 0.03-1.0 g.ml-1. MIC50 was 0.125 g.ml-1 and MIC90 was 0.125-0.5 g.ml-1. The range of MIC kou-Kang mouthwash against 21 Gram positive bacterial was 0.008-0.5 g.ml-1. The range of MIC50 and MIC90 were 0.015-0.125 g.ml-1 and 0.015-0.5 g.ml-1, respectively. The value of MIC was 0.015 g.ml-1 against candidia albicans. The acute toxic test indicated that the maximum tolerance dose was 417.6 g.kg-1 and 210 times as much as the clinical dose a day. No death of animals or toxicity and side-effect occurred in the test. CONCLUSION: Kou-Kang mouthwash shows a potent antibacterial activity against various pathogens of the oral cavity. Its antibiotic activity against Gram positive bacteria was 2-8 times stronger than that against Gram negative bacteria. It has low toxicity and can be used in clinical application. 相似文献
973.
Meng-Luen Lee Lon-Yen Tsao Wun-Tsong Chaou Albert D Yang Kun-Tu Yeh Jou-Kou Wang Mei-Hwan Wu Hung-Chi Lue Ing-Sh Chiu Chung-I Chang 《Pediatric pulmonology》2002,33(1):1-11
We propose a haphazard branching theory to support the concept of bronchopulmonary malinosculations, and we apply this theory to classify congenital bronchopulmonary vascular malformation (BPVM) based on the anatomical results we have found. Between January 1990 and December 1997, a total of 22 pediatric patients (10 male and 12 female), aged 2 days to 14 years (median, 19.6 months), with congenital BPVM were enrolled in this retrospective study. Study modalities include the clinical features and plain chest films (n = 22) plus at least two of the following: echocardiography (n = 13), barium esophagraphy (n = 2), bronchoscopy (n = 4), contrast bronchography (n = 8), high-resolution direct coronal CT (n = 1) and electron beam or ultrafast CT (n = 1) of the chest, MRI (n = 10), MRA (n = 1), contrast cineangiocardiography (n = 9), surgery (n = 11), or autopsy (n = 2). The salient clinical features were recurrent lung infections in 14 patients, acute respiratory distress in 13, associated cardiovascular malformations in 8, dextroversion in 7, congestive heart failure in 7, dextrocardia in 4, and complex congenital heart diseases in 4. There were abnormal openings (malinosculations) of the pulmonary airway in 20 patients: to an artery in 12, to a vein in 8, and to the lung parenchyma in 9. These 22 patients with congenital BPVM can be classified into bronchial malinosculation (10 cases), arterial malinosculation (2 cases), and bronchoarterial malinosculation (10 cases). Congenital BPVM can be classified in terms of bronchopulmonary malinosculation based upon a haphazard branching theory, in which abnormal communications between two independent systems (primitive foregut system and aortic-pulmonary arch system) occurred coincidentally rather than causally. 相似文献
974.
De-coupling of cognitive performance and cerebral functional response during working memory in schizophrenia. 总被引:4,自引:0,他引:4
Working memory dysfunction is considered to be fundamental to the cognitive and clinical features evident in schizophrenia. Functional neuroimaging studies have begun to elucidate the neurobiological basis of such deficits, however, interpretation of these studies may be confounded by performance impairment, when the cognitive load exceeds the limited response capacity of patients with schizophrenia. In this study, patients were pre-selected on the basis of intact performance on a relatively low-load verbal working memory task, in order to mitigate against performance confounds. Subjects included 20 right-handed male subjects with chronic schizophrenia, and 20 right-handed, age-matched, male healthy controls, without personal or familial psychiatric history. All subjects underwent fMRI scanning whilst performing a verbal n-back task. There were no significant between-group differences in target identification; the patient group showed a significantly increased mean response latency. Both groups demonstrated robust fronto-parietal activation. In the control subjects, the power of functional response was positively correlated with reaction time in bilateral posterior parietal cortex, however, this coupling of behavioural performance and cerebral response was not evident in the patients. This deficit, apparent within the performance capacity of the patients, may represent a fundamental abnormality in schizophrenia, and may compromise performance at higher cognitive loads. 相似文献
975.
No impact of repeated endoscopic screens on gastric cancer mortality in a prospectively followed Chinese population at high risk. 总被引:6,自引:0,他引:6
B Riecken R Pfeiffer J L Ma M L Jin J Y Li W D Liu L Zhang Y S Chang M H Gail W C You 《Preventive medicine》2002,34(1):22-28
BACKGROUND: Gastric cancer (GC) is the leading cause of cancer deaths in China. Our study prospectively evaluated the impact of repeated endoscopic screens on GC mortality in a high-risk population in China. METHODS: Between 1989 and 1999, a population-based gastroscopic screening was conducted in 4,394 residents of Linqu County, China, a region with the highest rates of GC worldwide. Residents ages 35 to 64 years received initial gastroscopies with biopsies in 1989. Repeated endoscopies were performed in 1994 and 1999. Cancer occurrences and deaths were actively monitored throughout the entire period until July 2000. Mortality from GC was compared with expected values based on mortality rates obtained for Linqu in the 1990-1992 Chinese Cancer Mortality Survey. RESULTS: Between March 1989 and July 2000, 39,303 person-years were accumulated; 85 new GCs occurred, 29 (34.5%) were in early stage. Fifty-eight cases (68%) were identified at one of the screens. The number of observed deaths from GC (37) was close to the expected (36.8). The standardized mortality ratio was 1.01 (95% CI 0.72-1.37) for the entire cohort, 1.13 (95% CI 0.77-1.57) for males, and 0.65 (95% CI 0.26-1.32) for females. CONCLUSIONS: Despite high population coverage with repeated screens, no reduction in GC mortality was observed in this high-risk population in China. 相似文献
976.
977.
E Maquarre C Artus Z Gadhoum C Jasmin F Smadja-Joffe J Robert-Lézénès 《Leukemia》2005,19(12):2296-2303
We have recently reported that ligation of the CD44 cell surface antigen with A3D8 monoclonal antibody (mAb) triggers incomplete differentiation and apoptosis of the acute promyelocytic leukemia (APL)-derived NB4 cells. The present study characterizes the mechanisms underlying the apoptotic effect of A3D8 in NB4 cells. We show that A3D8 induces activation of both initiator caspase-8 and -9 and effector caspase-3 and -7 but only inhibition of caspase-3/7 and caspase-8 reduces A3D8-induced apoptosis. Moreover, A3D8 induces mitochondrial alterations (decrease in mitochondrial membrane potential DeltaPsi m and cytochrome c release), which are reduced by caspase-8 inhibitor, suggesting that caspase-8 is primarily involved in A3D8-induced apoptosis of NB4 cells. However, the apoptotic process is independent of TNF-family death receptor signalling. Interestingly, the general serine protease inhibitor 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF) decreases A3D8-induced apoptosis and when combined with general caspase inhibitor displays an additive effect resulting in complete prevention of apoptosis. These results suggest that both caspase-dependent and serine protease-dependent pathways contribute to A3D8-induced apoptosis. Finally, A3D8 induces apoptosis in all-trans-retinoic acid-resistant NB4-derived cells and in APL primary blasts, characterizing the A3D8 anti-CD44 mAb as a novel class of apoptosis-inducing agent in APL. 相似文献
978.
Stevens-Johnson syndrome during anti-tuberculosis chemotherapy in HIV-seropositive patients: report on six cases 总被引:1,自引:0,他引:1
Hypersensitivity reactions may occur during antituberculous chemotherapy. Severe reactions are rare, and in the three years 1983-86 during which we have both worked in Africa managing large numbers of patients with tuberculosis we only saw one or two cases with severe and generalised cutaneous hypersensitivity. In the last 12 months, however, there have been a number of cases with severe Stevens-Johnson syndrome which developed during antituberculous chemotherapy and has invariably been associated with seropositivity to HIV (human immunodeficiency virus). 相似文献
979.
Hemorrhage associated with mandibular osteotomies, especially to the extent that it becomes life threatening, is a rare occurrence and its risk is less than that following maxillary orthognathic surgery. Twenty-one cases of significant bleeding following mandibular sagittal split ramus osteotomies, vertical and oblique ramus osteotomies, and genioplasties are presented. Life-threatening hemorrhage associated with mandibular osteotomies is primarily an intraoperative problem and the incidence of major postoperative and recurrent hemorrhage is not as great as following maxillary osteotomies. Suggestions for the avoidance and treatment of these bleeding complications are discussed. 相似文献
980.