全文获取类型
收费全文 | 25421篇 |
免费 | 1642篇 |
国内免费 | 422篇 |
专业分类
耳鼻咽喉 | 423篇 |
儿科学 | 276篇 |
妇产科学 | 327篇 |
基础医学 | 4240篇 |
口腔科学 | 418篇 |
临床医学 | 2249篇 |
内科学 | 5108篇 |
皮肤病学 | 856篇 |
神经病学 | 1806篇 |
特种医学 | 1981篇 |
外科学 | 3024篇 |
综合类 | 89篇 |
现状与发展 | 1篇 |
一般理论 | 6篇 |
预防医学 | 856篇 |
眼科学 | 649篇 |
药学 | 2797篇 |
中国医学 | 414篇 |
肿瘤学 | 1965篇 |
出版年
2024年 | 13篇 |
2023年 | 208篇 |
2022年 | 777篇 |
2021年 | 1103篇 |
2020年 | 532篇 |
2019年 | 758篇 |
2018年 | 928篇 |
2017年 | 736篇 |
2016年 | 1165篇 |
2015年 | 1471篇 |
2014年 | 1674篇 |
2013年 | 1902篇 |
2012年 | 2558篇 |
2011年 | 2513篇 |
2010年 | 1516篇 |
2009年 | 1184篇 |
2008年 | 1514篇 |
2007年 | 1429篇 |
2006年 | 1159篇 |
2005年 | 1092篇 |
2004年 | 897篇 |
2003年 | 693篇 |
2002年 | 545篇 |
2001年 | 268篇 |
2000年 | 231篇 |
1999年 | 150篇 |
1998年 | 87篇 |
1997年 | 53篇 |
1996年 | 40篇 |
1995年 | 34篇 |
1994年 | 26篇 |
1993年 | 23篇 |
1992年 | 37篇 |
1991年 | 25篇 |
1990年 | 25篇 |
1989年 | 27篇 |
1988年 | 12篇 |
1987年 | 18篇 |
1986年 | 14篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
31.
32.
Pil Whan Yoon Jong Yeal Kang Chul-Ho Kim Soong Joon Lee Jeong Joon Yoo Hee Joong Kim Sung Keun Kang Ju Hyeon Min Kang Sup Yoon 《Clinics in Orthopedic Surgery》2021,13(1):37
BackgroudOutcomes of traditional treatment for osteonecrosis of the femoral head (ONFH) are not always satisfactory. Hence, cell-supplementation therapy has been attempted to facilitate necrotic-tissue regeneration. Adipose-derived mesenchymal stem cell (ADMSC) transplantation is potentially advantageous over bone marrow-derived MSC implantation, but its outcomes for ONFH remain unclear. The aim of this study was to determine 2-year radiological and clinical outcomes of culture-expanded autologous ADMSC implantation for ONFH.MethodsEighteen hips with necrotic lesions involving ≥ 30% of the femoral head were included. ADMSCs were harvested by liposuction and culture expanded for 3 passages over 3 weeks. With a 6-mm single drilling, ADMSCs were implanted into the necrotic zone. All patients underwent magnetic resonance imaging (MRI), single-photon emission computed tomography/computed tomography (SPECT/CT) at screening and 6 months, 12 months, and 24 months postoperatively. The primary outcome was the change in the size of necrotic area on MRI. Secondary outcomes were changes in clinical scores and radioisotope uptake on SPECT/CT. Conversion total hip arthroplasty (THA) was defined as the endpoint.ResultsPreoperatively, the necrotic lesion extent was 63.0% (38.4%–96.7%) of the femoral head. The mean Harris hip score was 89.2, the University of California at Los Angeles (UCLA) score was 5.6, and Western Ontario and McMaster Universities Arthritis index (WOMAC) was 79.4. Three patients underwent THA and 1 patient died in an accident. Finally, 11 patients (14 hips) were available for ≥ 2-year follow-up. At the last follow-up, no surgery-related complications occurred, and 14 of 17 hips (82%) were able to perform daily activities without THA requirement. There was no significant decrease in lesion size between any 2 intervals on MRI. However, widening of high signal intensity bands on T2-weighted images inside the necrotic lesion was observed in 9 of 14 hips (64%); 11 of 14 hips (79%) showed increased vascularity on SPECT/CT at 2 years postoperatively. No significant differences were observed between preoperative and 24-month mean Harris hip score (89.2 vs. 88.6), WOMAC (79.4 vs. 75.7), and UCLA score (5.6 vs. 6.2).ConclusionsOur outcomes suggest that culture-expanded ADMSC implantation is a viable option for ONFH treatment without adverse events. 相似文献
33.
Ahn YK Park JC Park WS Kim NH Kim JW Kim SH Cho JH Jeong MH Cho JG Kang JC 《Journal of Korean medical science》1999,14(5):571-574
Epicardial fat may anteriorly produce an echo-free space that can be mistaken for pericardial fluid. We recently experienced a 67-year-old woman with prominent epicardial fat which was presented as an echogenic tumor-like mass. She underwent open pericardiostomy to relieve large amount of pericardial effusion. Operative findings revealed only prominent epicardial fat. Biopsy of the pericardial and fat tissues revealed an inflammation and normal fat cells without any malignant cell infiltration. 相似文献
34.
RATIONALE AND OBJECTIVES: To evaluate the short-term effects of a new nitinol stent on canine arteries. METHODS: Eighteen nitinol mesh stents were placed in abdominal aortas, common iliac arteries, and renal arteries of six dogs. Angiography was performed to evaluate the patency rates and structural changes of arteries at 1 day, 3 weeks, 4 weeks, and 10 weeks after stent insertion. Gross and light microscopic examinations were performed after angiography. RESULTS: On angiography, the patency rate was 100%, and no thrombosis was observed. All side branches from stented segments were patent. The mean neointimal thickness over and between stent wires was 94 and 167 microns. No difference was found between the aorta and the small vessels. Histologically, the neointima was covered with endothelium and was composed of subintimal fibrosis with mild inflammation. CONCLUSIONS: The new type of nitinol mesh stent showed a high patency rate, with no thrombosis and relatively thin neointimal proliferation. 相似文献
35.
36.
When liriodendrin or syringin was incubated for 24 h with human intestinal bacteria, two metabolites, (+)-syringaresinol-beta-D-glucopyranoside and (+)-syringaresinol, from liriodendrin and one metabolite, synapyl alcohol, from syringin were produced. The metabolic time course of liriodendrin was as follows: at early time, liriodendrin was converted to (+)-syringaresinol-beta-D-glucopyranoside, and then (+)-syringaresinol. The in vitro cytotoxicities of these metabolites, (+)-syringaresinol and synapyl alcohol, were superior to those of liriodendrin and syringin. 相似文献
37.
Sequential production and activation of matrix-metalloproteinase-9 (MMP-9) with breast cancer progression 总被引:10,自引:0,他引:10
Sun Young Rha Joo Hang Kim Jae Kyung Roh Kyong Sik Lee Jin Sik Min Byung Soo Kim Hyun Cheol Chung 《Breast cancer research and treatment》1997,43(2):175-181
The degradation of the basement membrane by matrix-metalloproteinase(MMP) and serine protease is a critical pointin tumor invasion and metastasis. We measured theactivity of MMP-9 from 28 normal, 12 benignand 126 breast cancer tissues using gelatin zymographywith an image analysis system. ProMMP-9 was expressedin 17.5% of the cancer patients compared to2.5% in 40 non-cancerous tissues (p=0.014).The mature form of MMP-9 (82 kD) wasexpressed only in T2–T4 stages. During the earlyphase of breast cancer (DCIS and T1 stage)progression, only production of proMMP-9 increased. However, asthe cancer grew or invaded skin (T2–T4), orwith lymphovascular permeation, both production and activation ofMMP-9 increased. In conclusion, proMMP-9 production was themain cause of increased MMP-9 activity during theearly phase, while both production and activation increasedin the late phase of breast cancer. 相似文献
38.
Moon WK Chang KH Weinmann HJ Koh YH Im JG Yeon KM Han MC 《AJR. American journal of roentgenology》2000,174(5):1385-1390
OBJECTIVE: The objective of this study was to compare enhancement patterns of a blood-pool contrast agent, Gadomer-17, with those of gadopentetate dimeglumine in bacterial abscesses and VX2 carcinoma in rabbits. MATERIALS AND METHODS: Fourteen rabbits with experimentally induced bacterial abscesses and VX2 carcinoma in both thighs underwent dynamic contrast-enhanced MR imaging with Gadomer-17 and gadopentetate dimeglumine at a 24-hr interval. The enhancement ratios (postcontrast to precontrast signal intensities) of lesions in the same animal were assessed and correlated with microvessel density. RESULTS: For Gadomer-17, the enhancement ratio of the abscesses (1.66 +/- 0.39) peaked 15 min after the injection, while that of the carcinoma (2.05 +/- 0.16) peaked at 10 min. The enhancement ratios of the carcinoma were consistently higher than those of the abscesses up to 30 min. For gadopentetate dimeglumine, peak enhancement ratio of the abscesses (2.30 +/- 0.75) was seen 5 min after the injection, while that of the carcinoma (2.32 +/- 0.51) was seen at 3 min. The enhancement ratios of the carcinomas were significantly higher at 1 min, but significantly lower at 20-30 min, compared with those of the abscesses, as a result of rapid decrease of enhancement ratios in the carcinomas. The microvessel density was 9.8 +/- 5.2 vessels per field of view for the abscesses and 36.3 +/- 9.5 vessels per field of view for the carcinoma (p < 0.001). CONCLUSION: Delayed peak enhancement and slow decay were found in both bacterial abscess and VX2 carcinoma with Gadomer-17, whereas early peak enhancement and rapid decay were found especially in VX2 carcinoma with gadopentetate dimeglumine. Enhancement ratios on MR imaging with a blood-pool contrast agent correlated well with the microvessel density in bacterial abscess and VX2 carcinoma. 相似文献
39.
Boo-Kyung Han Jung-Gi Im Hak Soo Kim Jin Mo Koo Hong Dae Kim Kyung Mo Yeon 《Korean journal of radiology》2000,1(3):127-134
Objective
To determine the extent to which thin-section and volumetric three-dimensional CT can depict airway reactivity to bronchostimulator, and to assess the effect of different airway sizes on the degree of reactivity.Materials and Methods
In eight dogs, thin-section CT scans were obtained before and after the administration of methacholine and ventolin. Cross-sectional areas of bronchi at multiple levels, as shown by axial CT, proximal airway volume as revealed by three-dimensional imaging, and peak airway pressure were measured. The significance of airway change induced by methacholine and ventolin, expressed by percentage changes in cross-sectional area, proximal airway volume, and peak airway pressure was statistically evaluated, as was correlation between the degree of airway reactivity and the area of airways.Results
Cross-sectional areas of the bronchi decreased significantly after the administration of methacholine, and scans obtained after a delay of 5 minutes showed that normalization was insufficient. Ventolin induced a significant increase in cross-sectional areas and an increase in proximal airway volume, while the effect of methacholine on the latter was the opposite. Peak airway pressure increased after the administration of methacholine, and after a 5-minute delay its level was near that of the control state. Ventolin, however, induced no significant decrease. The degree of airway reactivity did not correlate with airway size.Conclusion
Thin-section and volumetric spiral CT with three-dimensional reconstruction can demonstrate airway reactivity to bronchostimulator. The degree of reactivity did not correlate with airway size. 相似文献40.
Karina Richani Roberto Romero Yeon Mee Kim Enola Cushenberry Eleazar Soto Yu Mi Han Jimmy Espinoza Chong Jai Kim 《The journal of maternal-fetal & neonatal medicine》2006,19(8):509-515
OBJECTIVE: Tissue microarray (TMA) technology allows simultaneous examination of the expression of many molecular markers (protein, mRNA, DNA, etc.) with high-throughput. The application of this technology, to date, has been largely confined to the study of cancer. Placental pathology poses unique challenges because of the size of the organ, its complex anatomy, as well as its histological heterogeneity. The objective of this study was to assess the feasibility and efficiency of TMAs for immunohistochemistry and in situ hybridization of placental tissues. STUDY DESIGN: TMAs were constructed using an automated tissue arrayer. Standard 0.6-mm or 1-mm microarray needles were used. Villous parenchyma, basal plate, and chorioamniotic membranes were targeted in each block. Five mum-thick TMA sections underwent immunohistochemical analysis of both cytoplasmic and nuclear antigens using a panel of antibodies against a variety of cytoplasmic [cytokeratin-7, vascular endothelial growth factor (VEGF), and protein Z], membranous (endoglin), and nuclear (c-fos and c-jun) antigens. mRNA in situ hybridization for surfactant protein A (SP-A) and chromogenic in situ hybridization for the Y chromosome (DYZ1) were also performed. RESULTS: Validation of TMA immunoreactivity demonstrated comparable results with corresponding whole sections. When a two-tiered scoring system (positive/negative) was employed, there was agreement between two and three cores and whole tissue sections (kappa>0.7). When a three-tiered scoring system (negative, weak-positive, or strong-positive) was used, the data from three cores showed the highest agreement with whole tissue sections (kappa >0.7). In situ hybridization experiments for mRNA and DNA were also successful in that the signals were readily detectable. Successful transfer from the donor block to the recipient block differed according to the anatomical compartment. The transfer efficiency of villous parenchyma, basal plate, and chorioamniotic membranes were 96.9% (875/903), 76.7% (115/150), and 75.4% (224/297), respectively. CONCLUSION: TMA is a practical and effective tool for high-throughput molecular analysis of the human placenta. Duplicate and triplicate cores offer agreement with whole tissue sections for two-category distinction immunostaining. TMA also affords relevant results from in situ hybridization experiments for mRNA and DNA. The major advantages are the conservation of tissues and reagents, simultaneous comparison of molecular markers in different anatomical compartments of the placenta, and reduction of experimental error. 相似文献