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   35111篇
  免费   3057篇
  国内免费   1269篇
耳鼻咽喉   338篇
儿科学   601篇
妇产科学   562篇
基础医学   5313篇
口腔科学   996篇
临床医学   3240篇
内科学   6390篇
皮肤病学   614篇
神经病学   2876篇
特种医学   1251篇
外国民族医学   3篇
外科学   4550篇
综合类   3112篇
现状与发展   1篇
一般理论   8篇
预防医学   2153篇
眼科学   718篇
药学   3366篇
  5篇
中国医学   585篇
肿瘤学   2755篇
  2023年   164篇
  2022年   377篇
  2021年   636篇
  2020年   412篇
  2019年   525篇
  2018年   791篇
  2017年   646篇
  2016年   633篇
  2015年   801篇
  2014年   1016篇
  2013年   1194篇
  2012年   1648篇
  2011年   1711篇
  2010年   1036篇
  2009年   861篇
  2008年   1444篇
  2007年   1521篇
  2006年   1399篇
  2005年   1235篇
  2004年   1071篇
  2003年   936篇
  2002年   803篇
  2001年   2380篇
  2000年   2298篇
  1999年   1927篇
  1998年   763篇
  1997年   527篇
  1996年   368篇
  1995年   313篇
  1994年   290篇
  1993年   252篇
  1992年   1051篇
  1991年   923篇
  1990年   811篇
  1989年   909篇
  1988年   819篇
  1987年   751篇
  1986年   700篇
  1985年   616篇
  1984年   385篇
  1983年   321篇
  1982年   182篇
  1981年   144篇
  1980年   118篇
  1979年   204篇
  1973年   93篇
  1972年   92篇
  1971年   94篇
  1970年   83篇
  1968年   83篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
There is little information concerning the effects of passive exercise training in healthy humans. This prompted an investigation to evaluate muscle activity and the associated changes in strength and lean body mass resulting from a passive exercise program. Twenty-eight healthy volunteers, aged 26 to 44 years, participated in this six-week study. Lean body mass changes were evaluated by tetrapolar bioelectric impedance measurements, strength changes by isokinetic strength evaluation, and muscle activity by surface EMG techniques. Reproducible muscle activity was recorded in all three muscles studied during two of three preselected exercises. This involuntary muscle activity was attributed to fusimotor and postural reflexes. No significant change (p greater than .05), however, occurred in muscle strength or lean body mass at the end of the six weeks. Lack of these physiologic changes in light of the documented muscle activity is attributed to insufficient training effect.  相似文献   
102.
曲马多胶囊对中重度癌痛的临床镇痛效果   总被引:33,自引:1,他引:32  
  相似文献   
103.
Y Q Feng 《中华外科杂志》1992,30(10):610-1, 636
70 hepatic resections were performed using 2450 MHz microwave scalpel. Primary diseased included hepatocellular carcinoma (46 cases), hemangioma (18), hepatobiliary tract stone (2), biliary cystadenoma (1), inflammatory pseudotumor of the live (1), metastatic liver cancer (2). Hemostasis was excellent despite liver cirrhosis in all cases. The average amount of blood loss and blood transfusion was 249 ml and 294 ml respectively. Blood transfusion was not necessary in 30 patients. All cases were free from postoperative bleeding from the liver stump and abdominal infection. No complications attributable to microwave coagulation were noted. We conclude that this new operative technique can be used safely and easily in the field of hepatic surgery.  相似文献   
104.
105.
Although glucocorticoids are widely used to stimulate fetal/neonatal lung function, they also interfere with cellular development in the central nervous system. Dexamethasone was administered to pregnant rats in late gestation at a dose (0.8 mg/kg) that lies just above the threshold for stimulation of lung surfactant synthesis, and the impact on ornithine decarboxylase (ODC) was evaluated in three brain regions. Dexamethasone treatment produced an initial inhibition of basal ODC activity followed by postnatal elevations, a pattern known to be associated with delays in cell replication and differentiation. Dexamethasone also interfered with the ability of the 1-day-old neonate to turn off ODC acutely in response to a 2-h period of maternal separation; as this response conserves energy in the absence of the dam, the effect of dexamethasone is maladaptive. Additionally, dexamethasone sensitized the neonatal brain to hypoxia: the acute increase of ODC associated with a 2-h exposure to 7% O2 was exacerbated in 8-day-old rats exposed to dexamethasone prenatally. These results suggest that administration of dexamethasone, in doses that promote respiratory competence, delays cell development in the central nervous system and renders the brain more vulnerable to adverse neonatal conditions, such as maternal separation or hypoxia.  相似文献   
106.
It is documented that alkaline phosphatase (AP) plays an important role in bone mineralization. Considering that TN-AP is expressed in periodontal ligament fibroblasts, renal epithelial cells, and vascular endothelial cells, and that TN-AP is both a calcium-/phosphate-binding protein and a phosphohydrolytic enzyme, we hypothesize that membrane-bound AP also plays an important role in the initiation of physiological and pathological mineralizations in tissues other than bone and cartilage. To test this hypothesis, nonosteoblast cell lines, including a fibroblast line, a renal epithelial line, and a capillary endothelial line, were stably transfected to express high levels of rat bone AP on their cell surfaces. These rat bone AP-expressing cells were then cultured on filter membranes in the presence or absence of β-glycerol phosphate. von Kossa staining for calcium phosphate and transmission electron microscopy with electron diffraction analysis for minerals were employed to investigate the effect of membrane AP on extracellular calcium phosphate mineralization. Our results indicated that AP expression on these nonosteoblast-like cell surfaces have induced extracellular hydroxyapatite (HAP) mineralization. Our findings support the concept that membrane-bound AP contributes to extracellular apatitic mineralization by mechanisms that do not necessarily involve its hydrolase activity. They also suggest that AP might be important for the initiation of pathological mineralization in nonosteogenic tissues. Received: 11 January 1996 / Accepted: 31 October 1996  相似文献   
107.
Soda pop vending machine tipping continues to be a dangerous behavior that can result in lethal or crippling injuries. This study analyzes 64 cases of injuries secondary to crushing by a soda machine. All were male victims except one. The average age was 19.8 years with a range of 5-39 years. Thirteen victims sustained multiple trauma. Fifteen victims were killed. Increased public awareness coupled with support by the government and private industry has contributed to a sharp reduction in incidence of accidents and improved public safety.  相似文献   
108.
109.
This review is intended to provide a balanced view of the role of surgical burn wound excision and closure within the larger context of the total care and rehabilitation of patients with burn injury. The historical background leading to present practice is outlined. The salient technical and logistical problems associated with the performance of wound excision are discussed, with emphasis on the necessity for expeditiously completing these procedures which are associated with major blood loss. A realistic analysis of the results of excisional therapy in patients with burns of varying severity is presented. Benefits attributable to the surgical phase of therapy become progressively more difficult to identify as the size of deep burns increases beyond 20% of total body surface area.
Resumen La presente revisión propone proveer una visión equilibrada del papel de la resección tangencial quirúrgica de la quemadura y su cierre en el contexto más amplio del cuidado total y la rehabilitación de pacientes con lesiones térmicas. Se hace un recuento de los antecedentes históricos y se discuten los más prominentes problemas técnicos y logísticos relacionados con la resección tangencial de la quemadura con énfasis en la necesidad de implementar en forma expedita estos procedimientos, los cuales se asocian con pérdidas mayores de sangre. Se presenta el análisis realista de los resultados de la resección tangencial en pacientes con quemaduras de gravedad variable. Los beneficios atribuibles a la fase quirúrgica de la terapia se hacen progresivamente más difíciles de identificar en cuanto la extensión y profundidad sobrepasan el 20% de la superficie corporal.

Résumé Cette article fait le point sur les avantages et inconvénients respectifs de l'excision et la suture dans le cadre du traitement et la rééducation des grands brûlés. L'historique de cette technique est résumée. Les principaux problèmes de technique et de logistique de l'excision des brûlures sont discutés, en soulignant la nécessité d'assurer un geste rapide enfin de réduire les pertes sanguines. Une analyse réaliste des résultats de la technique excisionnelle des brûlures de sévérité variable est présentée. Les bénéfices directement en rapport avec la chirurgie deviennent plus difficiles à apprécier lorsque la surface brûlée dépasse 20 % de la surface corporéelle.
  相似文献   
110.
D Q Luo 《中华肿瘤杂志》1992,13(6):446-448
CT and MRI manifestations of 52 peripheral lung cancers located close to the pleural surface or mediastinal structures were studied correlating with the surgical and pathologic findings. Rib destruction as shown by CT and T2 weighted MRI showing the encroachment of tumor upon the chest wall were crucial in demonstrating chest wall invasion. An obtuse chest wall intersecting angle and the length of the neighboring borders of the tumor and chest wall were of limited value. Local pleural thickening was observed near the tumor in 54% of cases, over half of them showed obtuse angle between the tumor and the chest wall but without tumor invasion. T2 weighted MRI was more reliable than CT by showing different signal intensities for pleural thickening, inflammation, localized pleural effusion or tumor invasion to chest wall soft tissue.  相似文献   
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