全文获取类型
收费全文 | 41980篇 |
免费 | 2275篇 |
国内免费 | 842篇 |
专业分类
耳鼻咽喉 | 357篇 |
儿科学 | 945篇 |
妇产科学 | 333篇 |
基础医学 | 3275篇 |
口腔科学 | 404篇 |
临床医学 | 6038篇 |
内科学 | 8333篇 |
皮肤病学 | 186篇 |
神经病学 | 2486篇 |
特种医学 | 1134篇 |
外国民族医学 | 2篇 |
外科学 | 4982篇 |
综合类 | 5870篇 |
现状与发展 | 3篇 |
预防医学 | 2531篇 |
眼科学 | 2570篇 |
药学 | 4296篇 |
27篇 | |
中国医学 | 1186篇 |
肿瘤学 | 139篇 |
出版年
2024年 | 355篇 |
2023年 | 779篇 |
2022年 | 1248篇 |
2021年 | 1759篇 |
2020年 | 1607篇 |
2019年 | 1406篇 |
2018年 | 1403篇 |
2017年 | 1278篇 |
2016年 | 1274篇 |
2015年 | 1211篇 |
2014年 | 2589篇 |
2013年 | 2988篇 |
2012年 | 2090篇 |
2011年 | 2368篇 |
2010年 | 1752篇 |
2009年 | 1756篇 |
2008年 | 1870篇 |
2007年 | 1870篇 |
2006年 | 1675篇 |
2005年 | 1389篇 |
2004年 | 1215篇 |
2003年 | 978篇 |
2002年 | 876篇 |
2001年 | 842篇 |
2000年 | 669篇 |
1999年 | 620篇 |
1998年 | 549篇 |
1997年 | 576篇 |
1996年 | 477篇 |
1995年 | 524篇 |
1994年 | 465篇 |
1993年 | 405篇 |
1992年 | 421篇 |
1991年 | 372篇 |
1990年 | 346篇 |
1989年 | 305篇 |
1988年 | 316篇 |
1987年 | 286篇 |
1986年 | 262篇 |
1985年 | 291篇 |
1984年 | 297篇 |
1983年 | 176篇 |
1982年 | 241篇 |
1981年 | 193篇 |
1980年 | 170篇 |
1979年 | 149篇 |
1978年 | 130篇 |
1977年 | 76篇 |
1976年 | 64篇 |
1975年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
101.
(1) The spread of epidural analgesia following injection of 15ml of 2% mepivacaine was 17.3 ± 0.6, 14.3 ± 0.4, and 13.3 ± 0.7 spinal segments in cervical, thoracic, and lumbar epidural analgesia, respectively. The patients age showed significant correlation with the spread of epidural analgesia in cervical (r = 0.5776, p < 0.001), thoracic (r = 0.3758, p < 0.01), and lumbar area (r = 0.8195, p < 0.001). The spread of cervical epidural analgesia was more caudad than cephalad (p < 0.05), but in lumbar epidural analgesia it was more cephalad than caudad (p < 0.05). There was no difference between the cephalad and caudad spread in thoracic epidural analgesia.(2) The epidural pressure immediately after injection of 15ml of 2% mepivacaine into the lumbar epidural space at a constant pressure (80mmHg) correlated to the patients age (r = –0.5714, p < 0.001) and the spread of analgesia (r = –0.3904, p < 0.05). The lower epidural pressure associated with higher age, the wider spread of analgesia. There was no significant correlation between the residual pressure at 60 seconds and the age or the spread of analgesia.(Hirabayashi Y et al.: Spread of epidural analgesia following a constant pressure injection: an investigation of relationships between locus of injection, epidural pressure and spread of analgesia. J Anesth 1: 44–50, 1987) 相似文献
102.
Bone scan in the patellofemoral pain syndrome 总被引:3,自引:0,他引:3
Summary Eighty patients who complained of retropatellar pain underwent evaluation by bone scintigraphy, intraosseous pressure determination, radiography, arthroscopy and physical diagnostic tests. The bone scans showed that 48% of the painful knees had an increased uptake compared with 9% for the normal joints. A highly significant correlation was evident between an increased uptake and established chondromalacia. For the diagnosis of a high pressure patella, radiography was only 7% sensitive (6/88), compared with 44% (39/88) for bone scintigraphy and 78% for the clinical sustained flexion test. The positive predictive value of a bone scan for detecting a high pressure patella was 0.72 (39/54). The best predictor was a positive sustained flexion test with a predictive value of 0.85 (69/81).
Résumé Dix-huit malades se plaignant de douleurs rétro-patellaires ont été examinés par scintigraphie, mesure de la pression intra-osseuse, radiographie, arthroscopie et tests cliniques. La scintigraphie a montré que 48% des genoux douloureux présentaient une hyperfixation contre 9% des articulations normales. Il existait une corrélation évidente, hautement significative, entre l'hyperfixation et la chondropathie rotulienne. Pour le diagnostic d'hyperpression intrapatellaire, la radiographie n'était démonstrative que dans 7% des cas (6/88) alors que la scintigraphie l'était dans 44% (30/88) et le test clinique de «flexion prolongée» dans 78%. La valeur d'une scintigraphie positive en faveur du diagnostic d'hyperpression intra-patellaire est de 0.72 (39/54). L'élément le plus fiable est la positivité du test de flexion prolongée qui a une valeur prédictive de 0.85 (69/81).相似文献
103.
PEEP impedes thoracic duct drainage (LF). This can be counteracted by a thoracic duct fistula. Consequently, lung oedema (LOE) should develop during PEEP more slowly with LF at atmospheric pressure (LFAP) than with LF against jugular venous pressure (LFJVP). In 12 anaesthetized dogs LOE was produced by Ringer's solution i.v. (2.5 ml/min per kg) for 6 h during PEEP (10 mmHg) with either LFAP or LFJVP. Ringer's+PEEP greatly increased aortic, pulmonary artery and wedge pressures, JVP, and cardiac output. Colloid osmotic pressures in plasma and lymph were drastically reduced, pulmonary effective filtration pressure (EFP) rose by about 20 mmHg. LFJVP increased 7-fold, LFAP about 19-fold, the respective loss of plasma proteins was 1.83 and 1.06 g/kg during 6 h. Thermal-dye extravascular lung water showed an increment of 68 with LFJVP versus 43 l/h/g per mmHg with LFAP. Final lung water content was at any EFP (12.8–31.9 mmHg) lower with LFAP than with LFJVP amounting 512 with LFJVP versus 377 l/g/per mmHg with LFAP. LFAP decreased the development of LOE during PEEP by bypassing the PEEP-induced high JVP and thus facilitating the removal of interstitial fluid. It is hypothesized that a thoracic duct fistula might aid the treatment of patients with LOE due to ARDS and therefore requiring high levels of PEEP. 相似文献
104.
Jerry J. Buccafusco 《Brain research bulletin》1984,13(2):257-262
The formation of 3H-acetylcholine was measured in several brain regions of spontaneously hypertensive (SH) rats following intracerebroventricular injection of 3H-choline. Endogenous acetylcholine (ACh) also was measured and specific activity-time curves for brain ACh generated for control SH rats and for SH rats pretreated with methyldopa (100-200 mg/kg, IV). The relative turnover rates for ACh in several brain regions was estimated from the specific activity-time curves. The turnover rates of ACh in rostral hypothalamus, caudal hypothalamus, medulla oblongata and pons were reduced by 34-54%. Apparently synthesis was inhibited also since methyldopa produced relatively little effect on ACh levels. More rostral brain regions, thalamus-septum, midbrain and striatum, were not significantly affected by methyldopa. Methyldopa also reduced arterial pressure by 53/28 mmHg. The ability of methyldopa to inhibit the function of cholinergic neurons in selective brain regions may be responsible for its common "anticholinergic" side effects. Since centrally-acting anticholinergic drugs reduce arterial pressure in SH rats, it is possible that inhibition of brain ACh synthesis by methyldopa also may contribute to its antihypertensive action in experimental genetic hypertension. 相似文献
105.
目的:探讨高血压以昼夜血压模式指导药物治疗的疗效。方法:124例高血压患者被随机分为两组:观察组80例,采用以昼夜血压模式为依据,指导选用药物进行治疗,着重加强异常升高血压部份的降压治疗,同时加强血压监测;对照组仍按照常规方法治疗,6周为1疗程,治疗前和治疗后都检测血压和24小时动态血压。结果:观察组降压的总有效率和昼夜血压模式转为正常杓形态明显高于对照组,结论:高血压病患者以昼夜血压模式为依据指导用药降压治疗有较好的医疗效果。 相似文献
106.
Candida krusei发酵生产甘油过程中,菌体生长由玉米浆限制,菌体对玉米浆的得率为1.63g/g,培养其中玉米浆浓度相同时,增加渗透压或通过流加补料限制生长阶段的菌体生长,可使甘油生产阶段的比耗糖速率减慢,比耗糖速率保持在不很高的水平,可以因消耗的葡萄糖用于生长,维持,甘油和副产物形成所占比例的变化而提高甘油得率。 相似文献
107.
108.
109.
110.
Andrea Franz Daniel Herz Jens Raabe Ulrike Seeberger Christine Bollmann 《Foot and Ankle Surgery》2021,27(4):389-394
BackgroundFlatfoot is a frequent skeletal deformity in childhood that can be minimally invasively treated by arthroereisis. Question: Does the motion of juvenile flexible flatfoot normalize after arthroereisis?MethodPedographic measurements were obtained from 39 patients preoperatively, six months postoperatively and compared to a healthy group. The footprints were divided into 8 areas. The selected parameters were: contact area and force-time-integral.ResultsAfter surgery, a load shift from the medial to the lateral areas was detected under the midfoot and forefoot. The force-time-integral under the hallux normalized. However, under the lateral midfoot, the postoperative force-time-integral was significantly higher than in the control group.SignificanceThe study shows that arthroereisis is able to correct the medially displaced load distribution of juvenile flexible flatfoot. However, further investigations are required to find out if the higher punctual loading under the lateral midfoot may cause problems in the long term. 相似文献