全文获取类型
收费全文 | 34734篇 |
免费 | 3514篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 335篇 |
儿科学 | 1186篇 |
妇产科学 | 978篇 |
基础医学 | 5012篇 |
口腔科学 | 762篇 |
临床医学 | 4291篇 |
内科学 | 6031篇 |
皮肤病学 | 584篇 |
神经病学 | 3174篇 |
特种医学 | 923篇 |
外国民族医学 | 3篇 |
外科学 | 4059篇 |
综合类 | 523篇 |
一般理论 | 45篇 |
预防医学 | 4426篇 |
眼科学 | 490篇 |
药学 | 2669篇 |
中国医学 | 119篇 |
肿瘤学 | 2686篇 |
出版年
2023年 | 278篇 |
2022年 | 492篇 |
2021年 | 934篇 |
2020年 | 623篇 |
2019年 | 909篇 |
2018年 | 1043篇 |
2017年 | 679篇 |
2016年 | 739篇 |
2015年 | 874篇 |
2014年 | 1159篇 |
2013年 | 1500篇 |
2012年 | 2220篇 |
2011年 | 2204篇 |
2010年 | 1213篇 |
2009年 | 1028篇 |
2008年 | 1714篇 |
2007年 | 1685篇 |
2006年 | 1646篇 |
2005年 | 1556篇 |
2004年 | 1419篇 |
2003年 | 1245篇 |
2002年 | 1164篇 |
2001年 | 862篇 |
2000年 | 855篇 |
1999年 | 777篇 |
1998年 | 349篇 |
1997年 | 297篇 |
1996年 | 314篇 |
1995年 | 283篇 |
1994年 | 255篇 |
1993年 | 228篇 |
1992年 | 592篇 |
1991年 | 504篇 |
1990年 | 506篇 |
1989年 | 451篇 |
1988年 | 431篇 |
1987年 | 434篇 |
1986年 | 420篇 |
1985年 | 386篇 |
1984年 | 306篇 |
1983年 | 248篇 |
1982年 | 197篇 |
1981年 | 179篇 |
1980年 | 172篇 |
1979年 | 280篇 |
1978年 | 214篇 |
1977年 | 175篇 |
1974年 | 196篇 |
1973年 | 188篇 |
1972年 | 191篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
The zygomatico-temporal approach to the base of the skull is a relatively new but established surgical technique. The approach involves the removal of the zygomatic bone to provide access to the skull base, middle cranial fossa, parasellar region and interpeduncular cistern with minimal brain retraction. An excellent view of the bifurcation of the basilar artery and suprasellar region is provided. The outcome of 11 patients undergoing this procedure is reported with particular reference to the post-operative morbidity and the cosmetic result. 相似文献
63.
64.
Sixteen unipolar depressed patients were treated with cognitive therapy for 12 weeks. Pretreatment 24-hour urinary MHPG levels were unable to predict treatment response. There was a nonsignificant trend for cognitive therapy responders to show a decrease in MHPG during treatment when compared to nonresponders. 相似文献
65.
Adenosine as a vasodilator in primary pulmonary hypertension 总被引:7,自引:0,他引:7
J M Morgan D G McCormack M J Griffiths C J Morgan P J Barnes T W Evans 《Circulation》1991,84(3):1145-1149
BACKGROUND. The acute administration of vasodilator drugs to patients with primary pulmonary hypertension has been advocated to identify those with reversible pulmonary vasoconstriction. Unfortunately, the usefulness of the drugs currently available is limited by accompanying systemic hypotension. A vasodilator with effects confined to the pulmonary circulation would therefore be advantageous in such patients. METHODS AND RESULTS. The purine nucleoside adenosine was infused into the pulmonary artery in seven patients with primary pulmonary hypertension (baseline pulmonary vascular resistance [PVR], 442-1,295 dyne/cm/sec-5) to determine its effect on PVR. In all patients, there was a dose-dependent and significant reduction (mean maximal percent decrease from baseline, 38.9%; p less than 0.001) in PVR mediated through a decrease in pulmonary artery pressure and an increase in cardiac output. Systemic vascular resistance (SVR) also decreased, but the ratio of PVR to SVR decreased (maximal mean percent decrease from baseline) by 10.5% (p less than 0.025), indicating that adenosine has a preferential vasodilator effect on the pulmonary circulation when administered in this manner. CONCLUSIONS. Because of its pharmacokinetic and vasodilator properties, adenosine may have a specific role in the investigation of primary pulmonary hypertension. 相似文献
66.
Results of previous studies have shown that when rats consume higher concentrations of ethanol during initiation both the amount consumed and the pattern of consumption change with the return to a lower concentration. In this study, an across-sessions breakpoint procedure in the sipper-tube model was used to examine the effect that experience with drinking higher concentrations (a concentration manipulation) of both ethanol and sucrose had on appetitive and consummatory behaviors. A follow-up study was then conducted in the ethanol-consuming group with across-session breakpoint and intake examined before, during, and after a 3% sucrose/10% ethanol solution was presented in the sipper tube. As ethanol concentration increased, intake was not changed. Exposure to higher ethanol concentrations had no effect on the amount of 10% ethanol consumed when retested. The exposure tended to increase appetitive behavior (breakpoint), but this effect was not unique to ethanol, as rats self-administering 3% sucrose showed a similar increase. When the combined ethanol-sucrose solution was available, a significant increase in both intake and appetitive responding occurred; however, there was no change from prior intake or breakpoint when 10% ethanol was retested. That the addition of sucrose to the ethanol solution significantly increased appetitive and consummatory behaviors supports the suggestion that the composition of the alcoholic beverage can have a strong influence over the control of self-administration. Because most consumption of ethanol by human beings is in solutions that contain mixers that alter the taste of the solution, this taste factor needs to be considered in the regulation of ethanol drinking. 相似文献
67.
R. Kazi V. Prasad R. Venkitaraman C.M. Nutting P. Clarke P. Rhys‐Evans K.J. Harrington 《Clinical otolaryngology》2006,31(6):525-530
Objective: To determine the effects of a total laryngectomy on the swallow and subsequent quality of life in head and neck cancer patients. Design: Cross‐sectional single centre cohort study. Setting: Head and Neck Oncology Unit, Tertiary Referral Unit. Patients: Sixty‐two patients who underwent total laryngectomy at our centre participated in the study. Methods: Subjects were stratified by age, sex, tumour stage, other procedures such as myotomy and nerve re‐implantation. Pharyngectomy, glossectomy, flap reconstruction, neck dissection and previous radio‐ and chemotherapy were also assessed to see if they affected swallow and subsequent quality of life. Main outcome was measured using the MD Anderson Dysphagia Inventory questionnaire. Results: Responses were received from 46 males and 16 females (response rate of 80.5%) with a mean age of 64.7 years (SD 9.4). Median follow‐up in patients was 90 months (range 1–276). The mean MD Anderson Dysphagia Inventory total score in our series of patients was 77.7 (SD 16.6). MD Anderson Dysphagia Inventory global score was 79.4 (SD 22.6), Emotional score was 77.7 (SD 17.8), Functional score 81.3 (SD 15.9) and Physical score was 74.1(SD 18). Statistically significant differences were seen between the emotional scores of glossectomised and non‐glossectomised patients (Mann Whitney, P = 0.04). No significant correlation was seen between the subscale scores and the remaining treatment variables such as age, gender, site, tumour stage, myotomy, nerve implantation, radiotherapy, reconstruction and major complications. Conclusion: This questionnaire study is the largest of its type to assess the swallow of patients who have undergone laryngectomy at a single centre. The overall result confirmed that most patients had a subjectively good swallow. Only glossectomy and the method of PE segment closure were shown to significantly affect swallowing outcomes following surgery. We recommend further work especially prospective studies pre and post surgery using this or similarly validated instruments to fully assess swallow in the laryngectomy population. 相似文献
68.
69.
Haemodynamic assessment of the femoropopliteal segment: comparison of pressure and Doppler methods using ROC curve analysis 总被引:1,自引:0,他引:1
Combined aorto-iliac and femoropopliteal vascular disease remains a problem in vascular surgery. Arteriography does not provide information on the relative contributions of the two lesions to the presenting symptoms. Aorto-iliac haemodynamics may reveal occult aorto-iliac disease but does not show whether combined proximal and distal reconstruction will be required to provide symptomatic relief. Haemodynamic assessment of both segments may help in this respect. A haemodynamic assessment of the femoropopliteal segment of 72 limbs in 38 patients is reported. The segmental pressure drop between a common femoral arterial cannula and a below-knee occlusion cuff is compared with a non-invasive Doppler method combining both transit time and damping factor. Comparison is made using receiver operating characteristic (ROC) curve analysis. The measurement of segmental pressure drop is more accurate than the Doppler method in detection of femoropopliteal stenoses of greater than 50 per cent of the luminal diameter (P less than 0.05). 相似文献
70.
M L Evans M M Graham P A Mahler J S Rasey 《International journal of radiation oncology, biology, physics》1987,13(4):563-567
A quantitative measure of the vascular permeability surface area product (PS) for albumin has been made using a double isotope technique. PS was significantly elevated in irradiated rat lung, heart, skin, and muscle, between 19 and 26 days following 18 or 25 Gray thorax irradiation. Administration of dexamethasone from 2 days before irradiation through the day of measurement suppressed the expected increase in PS in lung, heart, and muscle, but not in skin. Shorter periods of steroid administration were not as effective in suppressing this response to radiation exposure. Increased vascular permeability following radiation may be an essential element in the development of radiation fibrosis. We hypothesize that the ability to suppress this response could result in a long term reduction in the incidence of fibrosis. 相似文献