全文获取类型
收费全文 | 2488957篇 |
免费 | 184922篇 |
国内免费 | 5679篇 |
专业分类
耳鼻咽喉 | 35327篇 |
儿科学 | 78934篇 |
妇产科学 | 71872篇 |
基础医学 | 349770篇 |
口腔科学 | 71434篇 |
临床医学 | 217510篇 |
内科学 | 490454篇 |
皮肤病学 | 57597篇 |
神经病学 | 202055篇 |
特种医学 | 97002篇 |
外国民族医学 | 879篇 |
外科学 | 378200篇 |
综合类 | 58095篇 |
现状与发展 | 9篇 |
一般理论 | 876篇 |
预防医学 | 185199篇 |
眼科学 | 58253篇 |
药学 | 181485篇 |
5篇 | |
中国医学 | 5591篇 |
肿瘤学 | 139011篇 |
出版年
2018年 | 25871篇 |
2017年 | 20039篇 |
2016年 | 22500篇 |
2015年 | 25448篇 |
2014年 | 35871篇 |
2013年 | 53643篇 |
2012年 | 71855篇 |
2011年 | 75937篇 |
2010年 | 44903篇 |
2009年 | 43201篇 |
2008年 | 71084篇 |
2007年 | 76043篇 |
2006年 | 76980篇 |
2005年 | 74705篇 |
2004年 | 71654篇 |
2003年 | 68760篇 |
2002年 | 67123篇 |
2001年 | 119384篇 |
2000年 | 122463篇 |
1999年 | 102809篇 |
1998年 | 28544篇 |
1997年 | 25890篇 |
1996年 | 25421篇 |
1995年 | 24107篇 |
1994年 | 22221篇 |
1993年 | 20736篇 |
1992年 | 78733篇 |
1991年 | 75667篇 |
1990年 | 73497篇 |
1989年 | 70940篇 |
1988年 | 65679篇 |
1987年 | 64303篇 |
1986年 | 61145篇 |
1985年 | 58019篇 |
1984年 | 43988篇 |
1983年 | 37233篇 |
1982年 | 22582篇 |
1981年 | 20349篇 |
1979年 | 40555篇 |
1978年 | 28802篇 |
1977年 | 24595篇 |
1976年 | 22565篇 |
1975年 | 24668篇 |
1974年 | 29306篇 |
1973年 | 28534篇 |
1972年 | 27064篇 |
1971年 | 24928篇 |
1970年 | 23775篇 |
1969年 | 22552篇 |
1968年 | 21269篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
According to the current nutritional recommendations issued by professional diabetes and nutrition associations, diabetic patients should keep to a diet consisting of 45–60% carbohydrates, 10–20% protein, and not more than 35% fat. However, not all of these nutritional recommendations are evidence based. For example, current studies show that the intake of insoluble roughage may be underrepresented. It is also possible that diabetic patients could benefit from keeping to the lower end of the recommended range for carbohydrates (45%) and the upper end of the range advised for protein (20%). 相似文献
32.
Chronic transplant dysfunction is a complex dynamic pathogenic process. Clinically, a decrease in glomerular filtration rate (GFR) becomes apparent leading to chronic renal insufficiency and dialysis or death from cardiovascular events. Chronic transplant dysfunction can develop into a chronic alIograft nephropathy (CAN) as a specific entity with dynamic progression. CAN includes a collection of immunologic and non-immunologic factors, rejection, ischemia time, donor and recipient characteristics and toxicity of calcineurin inhibitors. Despite improvements in immunosuppression, the long-range prognosis of renal allografts has not improved. Whether modern immunosuppressive concepts with reduction or avoidance of calcineurin inhibitors and a therapy based on antimetabolites, such as mycophenolate or mTOR-inhibitors could lead to a prolongation of transplant survival, remains to be seen. 相似文献
33.
G Steinitz M C Martín N Gazit-Yaari M L Quesada J de la Nuez R Casillas U Malik Z B Begin 《Applied radiation and isotopes》2006,64(4):520-524
Multi-day signals, generally with duration of 2-10 days, are a prominent temporal variation type of radon (Rn) in geogas in the unsaturated zone. Rare multi-day Rn signals have been found which are characterized by: (a) a declining limb lasting up to 10 days which conforms to the radioactive decay of Rn, (b) recurs at the same location and (c) is recorded in diverse situations-volcanic and seismogenic. It suggested that a Rn blob is injected at a lower level on a steady upward flow of geogas whereby the rise and final fall of the signal are attributed to the edges of the blob while the central Rn-decay segment records the passing of the decaying blob itself. Rn-decay signals are a small subset of multi-day Rn signals which are considered as highly irregular and unusable for the understanding of geophysical processes. In difference, it is concluded that multi-day Rn signals are probably proxies of subtle geodynamic processes at upper crustal levels and are therefore significant for studying such processes. 相似文献
34.
Riemer H J A Slart Ali Agool Dirk J van Veldhuisen Rudi A Dierckx Jeroen J Bax 《Journal of nuclear medicine》2006,47(8):1307-1311
SPECT with 99mTc-labeled agents is better able to detect viability after nitrate administration. Nitrates induce vasodilation and may increase blood flow to severely hypoperfused but viable myocardium, thereby enhancing tracer delivery and improving the detection of viability. Quantitative data on the changes in blood flow are lacking in SPECT but can be provided by PET. The aim of the present study was to use PET to evaluate whether nitrate administration increases blood flow to chronically dysfunctional but viable myocardium. METHODS: 13N-Ammonia PET was used to quantitatively assess blood flow, and 18F-FDG PET was used as the gold standard to detect viable myocardium. Twenty-five patients with chronic ischemic left ventricular dysfunction underwent 13N-ammonia PET at rest and after nitrate administration. RESULTS: A significant increase in nitrate-enhanced blood flow was observed in viable segments (from 0.55 +/- 0.15 to 0.68 +/- 0.24 mL/min/g, P < 0.05). No statistically significant change in blood flow was observed in nonviable segments (0.60 +/- 0.20 vs. 0.55 +/- 0.18 mL/min/g). A ratio of at least 1.1 for nitrate-enhanced flow to resting flow allowed optimal detection of viable myocardium, yielding a sensitivity of 82% with a specificity of 100%. CONCLUSION: 13N-Ammonia PET showed a significant increase in nitrate-enhanced blood flow in viable myocardium, whereas blood flow remained unchanged after nitrate administration in nonviable myocardium. Nitrate use during myocardial perfusion imaging will lead to improved assessment of myocardial viability. 相似文献
35.
36.
D B Irving J L Cook H B Menz 《Journal of Science and Medicine in Sport》2006,9(1-2):11-22; discussion 23-4
37.
Glauber T Silva Alejandro C Frery Mostafa Fatemi 《Computerized medical imaging and graphics》2006,30(5):321-327
We study the image formation of vibro-acoustography systems based on a concave sector array transducer taking into account depth-of-field effects. The system point-spread function (PSF) is defined in terms of the acoustic emission of a point-target in response to the dynamic radiation stress of ultrasound. The PSF on the focal plane and the axis of the transducer are presented. To extend the obtained PSF to the 3D-space, we assume it is a separable function in the axial direction and the focal plane of the transducer. In this model, an image is formed through the 3D convolution of the PSF with an object function. Experimental vibro-acoustography images of a breast phantom with lesion-like inclusions were compared with simulated images. Results show that the experimental images are in good agreement with the proposed model. 相似文献
38.
Dr. H. Ptok R. Steinert F. Meyer K.-P. Kröll C. Scheele F. Köckerling I. Gastinger H. Lippert 《Der Chirurg》2006,77(8):709-717
BACKGROUND: The laparoscopic resection of rectal cancer shows morbidity and oncological safety comparable to the open approach, but morbidity increases after conversion to open resection. No oncological long-term results are available for the latter patients. METHODS: From 01/01/2000-31/12/2002, patients with curatively resected rectal cancer enrolled in a observational study were evaluated for morbidity, mortality, tumor- and local recurrence rate, paying attention to patients with conversion from laparoscopic to open resection. RESULTS: 237 (3.3%) of 7,189 patients underwent laparoscopic resection (ITT). These patients showed significantly more T1/2 tumors (P<0.001) in earlier UICC stages (P<0.001) than open resected patients. 35 (14.8%) of 237 laparoscopic procedures were converted. Compared with patients receiving complete laparoscopic or open resection, these patients showed significantly higher frequencies of intraoperative (P<0.001) and general postoperative complications (P=0.003) as well as the highest overall morbidity (P=0.031). After a median follow-up of 30.1 months, the highest 5-year local recurrence rate was found in the converted group (16.0%). The laparoscopically resected patients showed a local recurrence rate of 3.3%, patients with open resection of 12.4% (P=0.082). The disease-free survival rate did not differ between the groups (P=0.585). CONCLUSION: Laparoscopic resection of rectal cancer provides oncological results similar to open resection. After conversion, the short and oncological long-term outcomes were worse. Considering a conversion rate of 15%, only a strict indication for the laparoscopic approach can be allowed, and laparoscopic resection should be performed at centers. 相似文献
39.
40.