全文获取类型
收费全文 | 91471篇 |
免费 | 4949篇 |
国内免费 | 218篇 |
专业分类
耳鼻咽喉 | 1083篇 |
儿科学 | 2087篇 |
妇产科学 | 2039篇 |
基础医学 | 12377篇 |
口腔科学 | 3456篇 |
临床医学 | 7186篇 |
内科学 | 22076篇 |
皮肤病学 | 2140篇 |
神经病学 | 8147篇 |
特种医学 | 2154篇 |
外国民族医学 | 1篇 |
外科学 | 12240篇 |
综合类 | 432篇 |
一般理论 | 39篇 |
预防医学 | 7851篇 |
眼科学 | 1839篇 |
药学 | 6075篇 |
中国医学 | 327篇 |
肿瘤学 | 5089篇 |
出版年
2023年 | 575篇 |
2022年 | 491篇 |
2021年 | 1645篇 |
2020年 | 976篇 |
2019年 | 1693篇 |
2018年 | 2835篇 |
2017年 | 1833篇 |
2016年 | 1932篇 |
2015年 | 2552篇 |
2014年 | 2757篇 |
2013年 | 3781篇 |
2012年 | 7734篇 |
2011年 | 8023篇 |
2010年 | 3692篇 |
2009年 | 2748篇 |
2008年 | 6648篇 |
2007年 | 6889篇 |
2006年 | 6753篇 |
2005年 | 6484篇 |
2004年 | 5839篇 |
2003年 | 5332篇 |
2002年 | 5017篇 |
2001年 | 1851篇 |
2000年 | 2359篇 |
1999年 | 1271篇 |
1998年 | 339篇 |
1997年 | 283篇 |
1996年 | 271篇 |
1995年 | 238篇 |
1994年 | 195篇 |
1993年 | 180篇 |
1992年 | 278篇 |
1991年 | 268篇 |
1990年 | 197篇 |
1989年 | 206篇 |
1988年 | 193篇 |
1987年 | 153篇 |
1986年 | 177篇 |
1985年 | 162篇 |
1984年 | 179篇 |
1983年 | 120篇 |
1982年 | 132篇 |
1981年 | 119篇 |
1980年 | 116篇 |
1979年 | 88篇 |
1978年 | 72篇 |
1977年 | 70篇 |
1976年 | 76篇 |
1974年 | 90篇 |
1973年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
161.
Ana Teresa Timóteo Andreia Mamede Maria de Lurdes Ferreira José Serra José Alberto Oliveira Rui Cruz Ferreira Jorge Quininha 《Revista portuguesa de cardiologia》2007,26(2):135-143
BACKGROUND: Nitrate therapy can induce ischemic preconditioning with a consequent increase in tolerance to ischemia. In the context of acute coronary syndromes (ACS), nitrates may result in a different presentation. with greater protection. OBJECTIVES: To investigate in a population of patients with ACS whether previous chronic use of nitrates results in a different presentation of ACS. METHODS: We studied 287 patients (65 +/- 13 years, 66% male) admitted to our department in the first six months of 2005 with ACS (with and without ST-segment elevation). Of these, 8% were under nitrate therapy at the time of admission. In this group, 27% presented ACS without ST-segment elevation, while in the group without nitrates this value was 58% (p = 0.005). By univariate analysis, the use of nitrates was a predictor of the preferential occurrence of non-ST-segment elevation ACS (OR 0.27, 95% CI 0.10-0.71). After correction for the potential influence of variables (age, gender, previous revascularization and smoking) by multivariate logistic regression, nitrate therapy remained a borderline predictor of clinical presentation as non-ST-segment elevation ACS (OR 0.37, 95% CI 0.13-1.04, p = 0.059). CONCLUSIONS: Previous use of nitrates was associated with a tendency to present as non-ST-segment elevation ACS. This finding may be explained by the hypothesis that nitrates induce pharmacological preconditioning, reducing the transmural extent of myocardial infarction. 相似文献
162.
Atilio Migues MD Gaston Slullitel MD Anibal Vescovo MD Felipe Droblas MD Marina Carrasco MD Hugo Perrin Turenne MD 《The Journal of foot and ankle surgery》2005,44(5):1043-357
The majority of foot and ankle operations are performed on an outpatient basis and often under some form of regional anesthesia. In this prospective, randomized study of 51 patients undergoing elective unilateral forefoot procedures, we compared 2 different anesthetic techniques: the peripheral foot blockade and the popliteal sciatic nerve block. Variables assessed included the quality of surgical anesthesia, postoperative analgesia, and the incidence of postoperative complications. The anesthesia was classified as effective if it was the sole anesthetic technique for the forefoot surgery. We found successful results in both groups: 92% in the foot block group and 96% in the popliteal block group. Analysis of time required to perform the anesthetic procedure showed a significant difference between the 2 groups, with foot block being considerably faster (14.3 minutes vs 19.2 minutes for popliteal block) (P = .0078). Foot block patients demonstrated 10.96 hours of analgesia, whereas popliteal block patients exhibited 14.32 hours (P = .132). With a mean follow-up of 5.7 months, we did not find anesthesia-related complications in any of the patients. Both techniques showed a high level of safety and efficacy, with no significant difference detected between them. Our patients showed a high rate of satisfaction with both procedures (96% for foot block patients and 96.1% for popliteal block patients) and reported a good discharge disposition. These data show that both procedures are safe and effective anesthetic techniques and well suited to forefoot ambulatory surgery. 相似文献
163.
Karina M S Freitas Marcos Roberto de Freitas José Fernando Castanha Henriques Arnaldo Pinzan Guilherme Janson 《American journal of orthodontics and dentofacial orthopedics》2004,125(4):480-487
Treatment stability is one of the most important objectives in orthodontics, but, despite decades of research, it is still agreed that the stability of aligned teeth is variable and largely unpredictable. This study aimed to evaluate the relapse of mandibular anterior crowding in patients treated without mandibular premolar extraction. The sample comprised 40 patients of both sexes with Class I or II malocclusions who received nonextraction treatment in the mandibular arch with edgewise mechanics. Lateral cephalograms and dental casts of each patient were obtained at pretreament, posttreatment, and 5 years postretention. Relapse of mandibular anterior crowding was assessed, and associations between this relapse and other clinical factors were also investigated. Mandibular anterior crowding was measured by the Little irregularity index, and the data were evaluated by the Mann-Whitney test. The mean relapse of mandibular anterior crowding was 1.95 mm (26.54%) over the long term. No clinical factor studied was predictive of crowding relapse in the long term. 相似文献
164.
Hervé Lamouliatte 《Acta endoscopica》2006,36(3):378-378
165.
Acute radiation reactions in oral and pharyngeal mucosa: tolerable levels in altered fractionation schedules. 总被引:3,自引:0,他引:3
Jack F Fowler Paul M Harari Felix Leborgne José H Leborgne 《Radiotherapy and oncology》2003,69(2):161-168
PURPOSE:To investigate whether a predictive estimate can be obtained for a 'tolerance level' of acute oral and pharyngeal mucosal reactions in patients receiving head and neck radiotherapy, using an objective set of dose and time data. MATERIALS AND METHODS:Several dozen radiotherapy schedules for treating head and neck cancer have been reviewed, together with published estimates of whether they were tolerated or (in a number of schedules) not. Those closest to the borderline were given detailed analysis. Total doses and biologically effective doses (BED or ERD) were calculated for a range of starting times of cellular repopulation and rates of daily proliferation. Starting times of proliferation from 5 to 10 days and daily cellular doubling rates of 1-3 days were considered. The standard published form of BED with its linear overall time factor was used: BED=nd(1 + d/(alpha/beta) - Ln2(T - T(k))/alpha T(p) (see text for parameters). RESULTS: A clear progression from acceptable to intolerable mucosal reactions was found, which correlated with total biologically effective dose (BED in our published modeling), for all the head and neck cancer radiotherapy schedules available for study, when ranked into categories of 'intolerable' or 'tolerable'. A review of published mechanisms for mucosal reactions suggested that practical schedules used for treatment caused stimulated compensatory proliferation to start at about 7 days. The starting time of compensatory proliferation had little predictive value in our listing, so we chose the starting time of 7 days. Very short and very long daily doubling rates also had little reliability, so we suggest choosing a doubling time of 2.5 days as a datum. With these parameters a 'tolerance zone of uncertainty' could be identified which predicted acute-reaction acceptability or not of a schedule within a range of about 2-10 Gy in total BED. If concurrent chemoradiotherapy is used, our provisional suggestion is that this zone should be reduced by up to roughly 3-5 Gy10 in BED, with a request for further evidence. CONCLUSIONS:It is suggested that total BED should be used, as specified above. Parameters of alpha=0.35 Gy-(1), alpha/beta=10 Gy, Tk=7 days and Tp=2.5 days are suggested. The 'acute/ tolerance zone' then turns out to be 59-61 Gy10 for radiation-only treatments. Further information about the decrement caused by concurrent head-and-neck cancer chemoradiotherapy, possibly 3-5 Gy10, is required. 相似文献
166.
José M Quintana Inmaculada Arostegui Antonio Escobar Iratxe Lafuente Juan C Arenaza Isidoro Garcia Urko Aguirre 《BMC musculoskeletal disorders》2007,8(1):84
Background
To develop a sensitive and specific screening tool for knee and hip osteoarthritis in the general population of elderly people. 相似文献167.
Improvement in quality of life after initiation of lamotrigine therapy in patients with epilepsy in a naturalistic treatment setting. 总被引:1,自引:0,他引:1
Hervé Allain Stéphane Schück Fatima Nachit-Ouinekh Perrine Plouin Anne-Marie Brunon Jacques Boulliat Florence Mercier Alain Slama Michel Baulac Abdelkader El Hasnaoui 《Seizure》2007,16(2):173-184
Quality of life is impaired in patients with epilepsy and can be improved by effective therapy. Randomised clinical trials have shown that lamotrigine treatment is associated with improved quality of life. However, little information is available on quality of life or treatment effects in patients with epilepsy in the general population. The objective of this study was to estimate the impact of lamotrigine on quality of life in a naturalistic treatment setting. The study included adult patients with epilepsy in whom lamotrigine therapy was initiated. Each subject completed the Quality of Life in Epilepsy Inventory (QOLIE)-31 quality of life questionnaire at inclusion and at a follow-up visit in the next 4 months. Demographic information and medical history were provided by the investigator. These were evaluated as potential determinants of change in quality of life using logistic regression. Three hundred and forty-one patients were evaluated, 192 starting lamotrigine in combination with another drug, 90 as a first-line monotherapy, 45 as a switch from another drug and 14 as a reduction to monotherapy from a previous combination. Baseline scores on the QOLIE-31 ranged from 53.8 in the combination group to 69.5 in the first-line group. 34.6% of patients were considered to be responders, with no significant differences between treatment regimen. Most improvement was seen for the energy-fatigue and medication effects subscales and, for the first-line group, seizure worry. Seizure type was the only determinant of improvement of quality of life identified. In conclusion, lamotrigine treatment is associated with improved quality of life, regardless of treatment regimen. 相似文献
168.
Gregor Warnecke Murat Avsar Thomas Steinkamp Renate Reinhard Jost Niedermeyer André R Simon Axel Haverich Martin Strüber 《European journal of cardio-thoracic surgery》2005,28(3):454-460
OBJECTIVE: Tacrolimus has been shown to provide superior immunosuppression in various solid organ transplant settings. The purpose of our study was to compare the survival of porcine lung allografts after induction with either cyclosporine A (CsA) or tacrolimus. METHODS: Single lung transplantation from MHC mismatched donors was performed in 10 minipigs. Immunosuppression included 1.5 mg/kg per day methylprednisolone and 1.0 mg/kg per day azathioprine. CsA (n=5) was adjusted to trough levels of 300-500 ng/ml, tacrolimus (n=5) was adjusted to 16-26 ng/ml. All immunosuppressive drugs were discontinued on postoperative day (POD) 28. Allograft survival was monitored by sequential chest radiographs, bronchoscopy and transbronchial biopsy histology. Peripheral blood leukocytes were scanned for donor chimerism and CD3, CD4, CD8 and CD25 expression. RESULTS: The animals survived a 4-week course of immunosuppression without radiological or histological signs of rejection on POD 28. Median allograft survival in CsA-treated animals was 55+/-15 days and all animals rejected their grafts within 42 days after withdrawal of immunosuppression. In tacrolimus-treated animals, median survival was 152+/-65 days with the longest survivor being electively sacrificed on POD 390 (P=0.0064). The degree of donor leukocyte chimerism and the frequency of CD4+CD25+ T-cells were higher in the tacrolimus group, however, these differences were not statistically significant. CONCLUSION: The results of our study show that primary immunosuppression with tacrolimus is superior to cyclosporine after pulmonary allotransplantation in a large animal model. 相似文献
169.
170.