全文获取类型
收费全文 | 21198篇 |
免费 | 1259篇 |
国内免费 | 202篇 |
专业分类
耳鼻咽喉 | 133篇 |
儿科学 | 1245篇 |
妇产科学 | 299篇 |
基础医学 | 2585篇 |
口腔科学 | 411篇 |
临床医学 | 1334篇 |
内科学 | 3629篇 |
皮肤病学 | 442篇 |
神经病学 | 1325篇 |
特种医学 | 934篇 |
外国民族医学 | 5篇 |
外科学 | 2850篇 |
综合类 | 822篇 |
一般理论 | 1篇 |
预防医学 | 1458篇 |
眼科学 | 1085篇 |
药学 | 2049篇 |
6篇 | |
中国医学 | 307篇 |
肿瘤学 | 1739篇 |
出版年
2022年 | 272篇 |
2021年 | 412篇 |
2020年 | 285篇 |
2019年 | 309篇 |
2018年 | 379篇 |
2017年 | 300篇 |
2016年 | 375篇 |
2015年 | 437篇 |
2014年 | 611篇 |
2013年 | 814篇 |
2012年 | 1131篇 |
2011年 | 1150篇 |
2010年 | 717篇 |
2009年 | 590篇 |
2008年 | 953篇 |
2007年 | 976篇 |
2006年 | 902篇 |
2005年 | 865篇 |
2004年 | 769篇 |
2003年 | 782篇 |
2002年 | 724篇 |
2001年 | 631篇 |
2000年 | 639篇 |
1999年 | 590篇 |
1998年 | 323篇 |
1997年 | 297篇 |
1996年 | 254篇 |
1995年 | 235篇 |
1994年 | 181篇 |
1993年 | 198篇 |
1992年 | 368篇 |
1991年 | 410篇 |
1990年 | 361篇 |
1989年 | 431篇 |
1988年 | 328篇 |
1987年 | 331篇 |
1986年 | 262篇 |
1985年 | 286篇 |
1984年 | 240篇 |
1983年 | 218篇 |
1982年 | 142篇 |
1981年 | 128篇 |
1980年 | 121篇 |
1979年 | 190篇 |
1978年 | 136篇 |
1975年 | 142篇 |
1974年 | 143篇 |
1973年 | 136篇 |
1972年 | 123篇 |
1971年 | 142篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Cardiac injuries--a clinical and autopsy profile 总被引:3,自引:0,他引:3
P Kulshrestha B Das K S Iyer K A Sampath M L Sharma I M Rao P Venugopal 《The Journal of trauma》1990,30(2):203-207
One hundred two patients sustaining cardiac injuries over a 4-year period were analysed to highlight the natural history of the cardiac injuries. There were 45 blunt, 36 stab, and 21 gunshot injuries. The injury involved the ventricle in 85, atrium in seven, pulmonary artery in five cases, and resulted in crush injury to the heart in the remaining five cases. Thirty-three patients (32.3%) died on the scene and 58 (56.9%) died during the transportation. Only 11 patients (10.8%) reached the hospital alive, and ten of these patients survived following thoracotomy and repair of the cardiac injury. The factors influencing the natural course of cardiac injury were analysed: 2.2% of patients with blunt cardiac trauma reached the hospital alive compared to 19.4% with stab and 14.3% with gunshot injuries; ventricular injuries had a greater prehospital mortality compared to atrial or pulmonary artery injuries; 11.3% of patients sustaining injury to right ventricle reached the hospital alive compared to 3% of those with left ventricular injuries. These data emphasize the need for rapid transport, immediate recognition, and aggressive surgical management, to make a favourable impact on the natural history of cardiac injuries. 相似文献
142.
AJ van Geest† PJM Berretty† PJJM Klinkhamer‡ HAM Neumann§ 《Journal of the European Academy of Dermatology and Venereology》2002,16(5):529-531
BACKGROUND: Acquired cerebriform intradermal naevus (CIN) is a rare form of pseudo cutis verticis gyrata. CASE REPORT: A case of acquired CIN of the scalp in a 46-year-old male patient is presented. The clinical and histopathological presentations of CIN are described and the therapeutic possibilities are discussed. CONCLUSIONS: In each individual case the physician must decide whether to do surgery or follow a wait-and-see policy. There is little risk of malignant change of CIN, and surgical excision of such lesions often involves evident mutilation. 相似文献
143.
144.
K S Rao J E Warnick J W Daly E X Albuquerque 《The Journal of pharmacology and experimental therapeutics》1987,243(2):775-783
The mechanism of the twitch potentiating action of pumiliotoxin-B (PTX-B), an indolizidine alkaloid from the skin of the frog Dendrobates pumilio, was studied on frog skeletal muscles. In the presence of PTX-B, a single stimulus to the muscle produced either a burst of repetitive action potentials superimposed on a depolarizing afterpotential or a single potential with a prolonged afterpotential at junctional as well as extrajunctional regions of the frog skeletal muscle fibers. The alkaloid did not cause repetitive activity in quiescent cells or spontaneous contractions. The duration of the burst of action potentials was related inversely and the amplitude and duration of postburst depolarizing after-potential was related directly to the concentration of PTX-B. The typical pattern of repetitive action potentials and postburst depolarization induced by PTX-B could be mimicked by depolarizing the muscle membrane with current pulses of long duration (150-470 ms). Lowering the external calcium or sodium concentration reduced the ability of PTX-B to initiate repetitive action potentials, whereas a low external chloride concentration had no effect. The frequency of MEPPs evoked by potassium, but not the spontaneous MEPP frequency, was increased by PTX-B, suggesting a selective effect on evoked transmitter release. PTX-B evoked repetitive EPPs in response to a single stimulus applied to the nerve, which was dependent upon the external calcium ion concentration. The amplitudes of EPPs in the train were facilitated, and their amplitude increased linearly at the lowest calcium concentration, but not at concentrations from 0.45 to 1.8 mM.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
145.
AE Boothroyd BVS Murthy A Darbyshire AJ Petros 《Acta paediatrica (Oslo, Norway : 1992)》1996,85(12):1422-1425
Objective: Right upper lobe collapse is a common radiographic finding in intubated children. We hypothesized that deep suctioning and uncontrolled negative pressures during endotracheal tube suctioning were significant contributory factors. Methods : The incidence of right upper lobe (RUL) collapse in intubated, ventilated children on a paediatric cardiac intensive care unit was determined over a 3-month period ( n = 102). Graduated suction catheters and suction vacuums of < 165 cm H2 O were then introduced. Another prospective audit was carried out 3 months later ( n = 60). Results : We found that 24% developed RUL collapse and 4 developed an apical pneumothorax. Following the introduction of graduated catheters and controlled vacuums pressures, a significant reduction in the incidence of RUL collapse, to 7%, was observed ( p < 0.05). Conclusions : We conclude that high negative pressure and deep-suctioning causes RUL collapse in children. Any lobar collapse not only prolongs the child's stay in intensive care, but can be associated with further morbidity which may have a serious implication. By improving suctioning technique this morbidity can be significantly reduced. 相似文献
146.
Brain enzyme levels in CSF after cardiac arrest and resuscitation in dogs: markers of damage and predictors of outcome 总被引:1,自引:0,他引:1
P Vaagenes P Safar W Diven J Moossy G Rao R Cantadore S Kelsey 《Journal of cerebral blood flow and metabolism》1988,8(2):262-275
Levels of brain creatine kinase (CK), aspartate aminotransferase (ASAT), and lactate dehydrogenase (LD) in CSF after cardiac arrest were studied in dog models. Ventricular fibrillation cardiac arrest lasting 10 min or asphyxiation cardiac arrest lasting 0-10 min was followed by cardiopulmonary resuscitation and 96-h intensive care. Outcome was scored as neurologic deficit (0% = normal, 100% = brain death) and overall performance category (1 = normal, 5 = death). Both measures correlated with EEG return time after asphyxiation cardiac arrest, but not after ventricular fibrillation cardiac arrest. Peak activity of enzymes in CSF at 48-72 h post arrest correlated with outcome, and CK was the best predictor. Brain histopathologic damage score at autopsy 96 h post arrest correlated with CK level in CSF (r = 0.79, n = 39) and neurologic deficit (r = 0.70, n = 50). Ischemic neuronal changes occurred after ventricular fibrillation cardiac arrest of 10 min, and neuronal changes plus microinfarcts occurred after asphyxiation cardiac arrest of 1.5-10 min. Brain enzymes were decreased at 6 h post arrest in regions with worst histologic damage (gray matter of neocortex, hippocampus, caudate nucleus, cerebellum). Brain CK decreased further, ASAT remained low, and LD increased at 72 h after arrest. The temporal changes in CK level paralleled the temporal ischemic neuronal changes in the brain, and time to peak activity was unaffected by the severity of the ischemic insult. Peak activity of individual enzymes in CSF was determined predominantly by the brain concentration, but was also influenced by rate of decomposition. This "chemical brain biopsy method" represents a useful adjunctive tool to predict permanent, severe brain damage during comatose states after cardiac arrest and resuscitation. 相似文献
147.
A new iridoid glucoside, 5-deoxypulchelloside I, along with the three known iridoid glucosides, phlomiol, lamiid, and lamiidoside, were isolated from the leaves of CITHAREXYLUM FRUTICOSUM. The structure of the new compound was established by spectroscopic methods. 相似文献
148.
The relationship between various dietary constituents and colon cancer has been demonstrated by previous research. We conducted a study to investigate the combined effects of several dietary constituents on intestinal tumor incidence in azoxymethane (AOM)-induced colon cancer in rats. A nutritionally adequate, "low-risk" (LR) diet was formulated through nonextreme dietary manipulations of dietary fat, fiber, protein, vitamins A and E, and selenium. Seventy-two female F344 weanling rats were given three weekly subcutaneous injections of either AOM or physiological saline solution, and were maintained on either the LR or a "high-risk" (HR) diet. Food consumption and body weights were monitored on a weekly basis throughout the study. Tumor incidence was determined 36 weeks following the first injection of AOM. The incidence of adenocarcinomas in the LR diet group was 4.2% compared with 29.2% in the HR diet group. There were no significant differences in the incidence of small intestinal tumors or in the incidence of benign polyps between the diet groups. The results of the study indicated a significant protective effect of the various chemopreventive dietary factors when combined in an LR diet for colon cancer. 相似文献
149.
Rao G Flaherty P 《Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital》1989,16(3):163-168
Of the total number of pacemakers implanted each year, 6% must eventually be replaced because of infection, lead failure, or other problems. Often however, removal of the pacing leads is precluded by scarring at the tip of the leads. Because abandoned leads can cause serious problems, we initiated the present study to test the feasibility of using a laser to remove such leads. After performing in vitro experiments to establish the laser settings required for severing leads, we implanted 6 leads, from 4 different manufacturers, in 3 dogs. Five weeks later, we passed a laser fiber through each lead to the tip and delivered a 10-watt impulse for 2 seconds, which resulted in the successful removal of all the leads. When the dogs were killed 3 days later, postmortem examination revealed no thromboembolism in the heart or lungs and no myocardial damage. Subsequent experiments in 3 human cadaver hearts-involving leads implanted for 5 years, 2 years, and 2 months-yielded the same satisfactory results as did the canine experiments. 相似文献
150.
Septo-optic dysplasia: MR imaging 总被引:5,自引:0,他引:5
Septo-optic dysplasia is the diagnosis when optic nerve hypoplasia is seen in conjunction with dysgenesis of the septum pellucidum. Nearly two-thirds of these patients have hypothalamic-pituitary dysfunction, and half have schizencephaly. The disorder is difficult to classify because of the diversity of clinical and pathologic manifestations. Magnetic resonance images of 11 patients with clinical and radiographic evidence of septo-optic dysplasia were reviewed retrospectively. The "syndrome" appears to include two subsets of patients whose abnormalities have different embryogenesis and neuropathologic findings. The existence of these two subsets helps to explain the diversity of the clinical and radiologic findings. 相似文献