全文获取类型
收费全文 | 17461篇 |
免费 | 1459篇 |
国内免费 | 978篇 |
专业分类
耳鼻咽喉 | 328篇 |
儿科学 | 191篇 |
妇产科学 | 52篇 |
基础医学 | 583篇 |
口腔科学 | 330篇 |
临床医学 | 6880篇 |
内科学 | 1871篇 |
皮肤病学 | 32篇 |
神经病学 | 1257篇 |
特种医学 | 338篇 |
外国民族医学 | 3篇 |
外科学 | 2363篇 |
综合类 | 2362篇 |
现状与发展 | 1篇 |
预防医学 | 1457篇 |
眼科学 | 159篇 |
药学 | 691篇 |
73篇 | |
中国医学 | 717篇 |
肿瘤学 | 210篇 |
出版年
2024年 | 84篇 |
2023年 | 389篇 |
2022年 | 746篇 |
2021年 | 1109篇 |
2020年 | 1089篇 |
2019年 | 894篇 |
2018年 | 843篇 |
2017年 | 822篇 |
2016年 | 718篇 |
2015年 | 655篇 |
2014年 | 1306篇 |
2013年 | 1978篇 |
2012年 | 925篇 |
2011年 | 981篇 |
2010年 | 804篇 |
2009年 | 697篇 |
2008年 | 706篇 |
2007年 | 765篇 |
2006年 | 690篇 |
2005年 | 540篇 |
2004年 | 459篇 |
2003年 | 464篇 |
2002年 | 354篇 |
2001年 | 331篇 |
2000年 | 251篇 |
1999年 | 189篇 |
1998年 | 152篇 |
1997年 | 157篇 |
1996年 | 107篇 |
1995年 | 116篇 |
1994年 | 85篇 |
1993年 | 66篇 |
1992年 | 64篇 |
1991年 | 41篇 |
1990年 | 38篇 |
1989年 | 35篇 |
1988年 | 32篇 |
1987年 | 24篇 |
1986年 | 27篇 |
1985年 | 27篇 |
1984年 | 26篇 |
1983年 | 19篇 |
1982年 | 26篇 |
1981年 | 20篇 |
1980年 | 17篇 |
1979年 | 5篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
A series of cards each containing a two dimensional array of identical Snellen "E's" was used to determine best eccentric visual acuity in patients with macular disease having Snellen visual acuity of 20/70 or worse. Each "full field E" card simultaneously presents the same letter to foveal and parafoveal areas. This test can therefore determine quickly if potentially useful vision is present in any area of the central visual field. In our study of 37 eyes, 70% demonstrated potential visual acuity at least two times better than visual acuity measured by conventional methods, and 20% demonstrated at least a fourfold improvement. This suggests that most patients with macular disease do not spontaneously employ their best remaining area of retina for fixation. 相似文献
32.
Michael P. Cary Farica Zhuang Rachel Lea Draelos Wei Pan Sathya Amarasekara Brian J. Douthit Yunah Kang Cathleen S. Colón-Emeric 《Journal of the American Medical Directors Association》2021,22(2):291-296
ObjectivesTo evaluate a machine learning model designed to predict mortality for Medicare beneficiaries aged >65 years treated for hip fracture in Inpatient Rehabilitation Facilities (IRFs).DesignRetrospective design/cohort analysis of Centers for Medicare & Medicaid Services Inpatient Rehabilitation Facility–Patient Assessment Instrument data.Setting and ParticipantsA total of 17,140 persons admitted to Medicare-certified IRFs in 2015 following hospitalization for hip fracture.MeasuresPatient characteristics include sociodemographic (age, gender, race, and social support) and clinical factors (functional status at admission, chronic conditions) and IRF length of stay. Outcomes were 30-day and 1-year all-cause mortality. We trained and evaluated 2 classification models, logistic regression and a multilayer perceptron (MLP), to predict the probability of 30-day and 1-year mortality and evaluated the calibration, discrimination, and precision of the models.ResultsFor 30-day mortality, MLP performed well [acc = 0.74, area under the receiver operating characteristic curve (AUROC) = 0.76, avg prec = 0.10, slope = 1.14] as did logistic regression (acc = 0.78, AUROC = 0.76, avg prec = 0.09, slope = 1.20). For 1-year mortality, the performances were similar for both MLP (acc = 0.68, AUROC = 0.75, avg prec = 0.32, slope = 0.96) and logistic regression (acc = 0.68, AUROC = 0.75, avg prec = 0.32, slope = 0.95).Conclusion and ImplicationsA scoring system based on logistic regression may be more feasible to run in current electronic medical records. But MLP models may reduce cognitive burden and increase ability to calibrate to local data, yielding clinical specificity in mortality prediction so that palliative care resources may be allocated more effectively. 相似文献
33.
34.
Irma Ruslina Defi Chandrawati Gultom Maria Jessica Chorman Jennie Jennie 《Reumatologia》2021,59(2):98
IntroductionSystemic sclerosis/scleroderma (SSc) is a chronic autoimmune disease with connective tissue, multi-organ, and multisystem involvement. The disease has three main characteristics, namely vasculopathy, fibrosis, and autoimmunity. The effect of high-intensity interval training (HIIT) in aerobic exercise on other rheumatic diseases has been studied, for example in patients with rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA). The purpose of this work is to investigate the effectiveness of HIIT of aerobics exercise on improving the inspiratory muscle, quality of life and functional ability for systemic sclerosis subjects.Material and methodsThe study was conducted on patients with confirmed systemic sclerosis who met the inclusion criteria. The research was carried out for 12 months in the outpatient clinic and gait laboratory of the Department of Physical Medicine and Rehabilitation.ResultsAfter HIIT in aerobic exercise, we found significant changes in inspiratory muscle (SNIP values 45.67 [30.92] vs. 54.25 [22.71]), handgrip (13.14 [4.42] vs. 15.63 [4.08]), walking speed (184.70 [26.86] vs. 246.6 [12.30]), metabolic equivalent (3.53 [0.30] vs. 4.21 [1.25]) and Scleroderma-Specific Health Assessment Questionnaire Disability Index for all visual analog scale (VAS) domains except Disability Index. Exercise approaches are characterized by repeated cycles of exercise interrupted by rest. For a range of clinical conditions, HIIT in aerobic exercise is known to remedy blood vessel function.ConclusionsOur results suggest that HIIT in aerobic exercise has improved functional ability, respiratory muscle strength, and quality of life in SSc subjects. Training twice a week in a 12-week HIIT program is considered to be safe for this population. We have to consider internal and external factors that influenced the result. A larger sample and further exploration of the feasibility of combined exercise in SSc patients should be the focus for future research. 相似文献
35.
36.
目的研究蒸汽吸人性损伤犬伤后血浆肿瘤坏死因子水平的改变及其与吸入性损伤呼吸循环功能受损程度的关系.方法取犬15条,以蒸汽致重度吸入性损伤,分别于伤前、伤后1h、2h、3h、4h观察有呼气相气道阻力(RE)、心率(HR)、心输出量(CO)、动脉血氧分压(PaO2)、血浆TNF水平;伤后4h致死动物,取肺做病理检查.结果伤后1hTNF、RE升高,HR、CO、PaO2下降;TNF与RE正相关(r=O.965,P<O.01),与CO负相关(r=-0.824,P<O.05).结论严重蒸汽吸入性损伤激发TNF分泌,这是诱发肺损伤及循环系统甚至全身器官功能障碍的重要原因. 相似文献
37.
A standardized system to describe the pressure-flow characteristics of a given cannula has recently been proposed and has been termed the M-number system. Using 3 different sizes of aortic cannulas in 50 pediatric cardiac patients on hypothermic cardiopulmonary bypass, we analyzed the correlation between experimentally and clinically derived M-numbers and found it to be positive. Clinical M-numbers were typically 0.35 to 0.55 greater than experimental M-numbers and correlated inversely with a patient's temperature change; this was most probably due to increased blood viscosity arising from hypothermia. This inverse relationship was more marked in higher M-number cannulas. The clinical data obtained in this study suggest that the experimentally derived M-number correlates strongly with the clinical performance of the cannula and that the influence of temperature is significant. 相似文献
38.
The use of the iSTAT portable analyzer in patients undergoing cardiopulmonary bypass 总被引:1,自引:0,他引:1
Neil Roy Connelly MD Michael Magee MD Brian Kiessling MD 《Journal of clinical monitoring and computing》1996,12(4):311-315
Objective. To evaluate the utility of the iSTAT blood analyzer, a bedside device for hematocrit, sodium, potassium, and glucose measurement during cardiopulmonary bypass (CPB).Methods. Forty patients scheduled for elective CPB were evaluated prospectively. In addition to using the iSTAT analyzer, blood samples were analyzed at four time points: following induction of anesthetic, 10 min. after initiation of CPB, 60 min. after initiation of CPB, and following heparin neutralization by protamine. Blood glucose concentration was measured by the hospital laboratory using a Kodak Analyzer and by a glucose meter, electrolytes were evaluated by the Kodak Analyzer and BGE (a device which is commonly used for satellite laboratory determinations of electrolyte and blood gas results), and hematocrit samples were measured by the hospital laboratory using an NE 8,000 and a centrifuge. The means and standard deviations of the differences between the methods were calculated.Results. The hematocrit values determined by the iSTAT machine, when adjusted for the level of total protein (according to manufacturer's directions), differed from the laboratory values by 0.53 = 1.46 percentage points. An alternative to measuring total protein and making the adjustment is simply adding 1 % to the hematocrit in the pre-CPB period and 3% on-CPB or post-CPB, which we found to yield values that differed from the laboratory by 0.52 ± 1.42 percentage points. For all four tests (hematocrit, sodium, potassium, and glucose) the iSTAT had a similar relationship to the laboratory values as did the other commonly used means (centrifuge, BGE, and glucose meter) of clinical evaluation.Conclusion. In summary, we found that in patients undergoing CPB, the iSTAT values agreed sufficiently well with standard laboratory values and that the iSTAT instrument can be relied upon for bedside measurements.Presented in part at the Annual Meeting of the Society of Cardiovascular Anesthesiologists, Philadelphia, PA, May 1995, and at the 70th meeting of the IARS, Washington DC, March 1996. Supported in part by a grant by iSTAT Corporation. 相似文献
39.
Triiodothyronine (T3 ) and Cardiovascular Therapeutics: A Review 总被引:1,自引:0,他引:1
DAVID R. SALTER M.D. CORNELIUS M. DYKE M.D. ANDREW S. WECHSLER M.D. 《Journal of cardiac surgery》1992,7(4):363-374
Hypothyroidism is associated with an abnormal hemodynamic state characterized by decreased heart rate, stroke volume, output, and contractility, and increased systemic vascular resistance. Since cardiopulmonary bypass (CPB) and surgical stress can induce profound decreases in triiodothyronine (T3) levels, the hemodynamic consequences of "stress-induced" hypothyroidism and T3 repletion are of increasing clinical interest. Available data generally support the likelihood of a beneficial effect associated with T3 replacement in brain-dead organ donors and in cases of low cardiac output following CPB. Although hypotheses have been advanced to account for these salutary effects, the mechanism by which T3 may augment hemodynamic performance has not been precisely defined, particularly in the acute setting. Although additional research is needed to clarify these and other issues, preliminary findings with T3 replacement indicate that such investigation is warranted. 相似文献
40.
A. A. Geertsema M. P. de Vries H. K. Schutte J. Lubbers G. J. Verkerke 《European archives of oto-rhino-laryngology》1998,255(5):244-249
Tracheostoma valves are often required in the rehabilitation process of speech after total laryngectomy. Patients are thus
able to speak without using their hands to close the tracheostoma. The improved Groningen tracheostoma valve consists of a
“cough” valve with an integrated (“speech”) valve, which closes for phonation. The cough valve opens as the result of pressure
produced by the lungs during a cough. The speech valve closes by the airflow produced by the lungs, thus directing air from
the lungs into the esophagus at a deliberately chosen moment. An experimental setup with a computer-based acquisition program
was developed to measure the pressure at which the cough valve opened and the flow at which the speech valve closed. In addition,
the airflow resistance coefficient of the tracheostoma valve was defined and measured with an open speech valve. Both dry
air from a cylinder and humid expired air were used. Results showed a pressure range of 1–7 kPa to open the cough valve and
a flow range of 1.2–2.7 l/s to close the speech valve. These values were readily attained during speech, while the flow range
occurred above values reached in quiet breathing. The device appeared to function well in physiological ranges and was optimally
adjustable to an individual setting. No significant differences were measured between air from a cylinder and humid expired
air. Findings showed that methods used to obtain results could be employed as a reference method for comparing aerodynamic
characteristics of tracheostoma valves.
Received: 13 February 1997 / Accepted: 16 September 1997 相似文献