全文获取类型
收费全文 | 317940篇 |
免费 | 27795篇 |
国内免费 | 20505篇 |
专业分类
耳鼻咽喉 | 2736篇 |
儿科学 | 3744篇 |
妇产科学 | 5725篇 |
基础医学 | 37178篇 |
口腔科学 | 5561篇 |
临床医学 | 41956篇 |
内科学 | 50481篇 |
皮肤病学 | 3419篇 |
神经病学 | 17964篇 |
特种医学 | 11238篇 |
外国民族医学 | 143篇 |
外科学 | 33631篇 |
综合类 | 47552篇 |
现状与发展 | 64篇 |
一般理论 | 58篇 |
预防医学 | 20096篇 |
眼科学 | 9197篇 |
药学 | 32125篇 |
254篇 | |
中国医学 | 16057篇 |
肿瘤学 | 27061篇 |
出版年
2024年 | 950篇 |
2023年 | 4651篇 |
2022年 | 12016篇 |
2021年 | 15505篇 |
2020年 | 11448篇 |
2019年 | 10147篇 |
2018年 | 10796篇 |
2017年 | 9360篇 |
2016年 | 8941篇 |
2015年 | 13579篇 |
2014年 | 17030篇 |
2013年 | 15569篇 |
2012年 | 22959篇 |
2011年 | 25561篇 |
2010年 | 15635篇 |
2009年 | 12481篇 |
2008年 | 16697篇 |
2007年 | 16681篇 |
2006年 | 16429篇 |
2005年 | 16519篇 |
2004年 | 11031篇 |
2003年 | 10015篇 |
2002年 | 8617篇 |
2001年 | 7770篇 |
2000年 | 7998篇 |
1999年 | 8387篇 |
1998年 | 4960篇 |
1997年 | 4896篇 |
1996年 | 3776篇 |
1995年 | 3509篇 |
1994年 | 2992篇 |
1993年 | 1979篇 |
1992年 | 2837篇 |
1991年 | 2449篇 |
1990年 | 2086篇 |
1989年 | 1843篇 |
1988年 | 1591篇 |
1987年 | 1444篇 |
1986年 | 1154篇 |
1985年 | 914篇 |
1984年 | 565篇 |
1983年 | 428篇 |
1982年 | 262篇 |
1981年 | 236篇 |
1980年 | 214篇 |
1979年 | 263篇 |
1978年 | 141篇 |
1977年 | 112篇 |
1976年 | 97篇 |
1974年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Lei Wang Moyi Sun Yuegui Jiang Lianjia Yang Delin Lei Chao Lu Yinghua Zhao Pu Zhang Yaowu Yang Jianhu Li 《Journal of oral and maxillofacial surgery》2006,64(4):636-641
PURPOSE: Perineural invasion is a frequent occurrence in salivary adenoid cystic carcinoma (ACC) and may prevent complete surgical resection. Studies have indicated that nerve growth factor (NGF) and its high-affinity receptor tyrosine kinase A (TrkA) may play a role in perineural invasion in several malignancies in which perineural invasion is observed. The present study was conducted to investigate the expression of NGF and TrkA in salivary ACC and to examine the effects of NGF on adhesion, migration and invasion capacities of a salivary ACC cell line (SACC-83) in vitro. PATIENTS AND METHODS: Expression of NGF and TrkA was explored using immunohistochemistry in paraffin-embedded tissues of 32 cases of salivary ACC. The effects of NGF on in vitro adhesion, migration, and invasion capacities of the SACC-83 cell line were examined using an MTT assay and a modified Boyden chamber assay respectively. RESULTS: In ACC specimens, 31 (96.9%) and 32 (100%) tumors showed immunoreactivity for NGF and TrkA respectively. Significant correlations were found between NGF/TrkA expression levels and perineural invasion (P < .05). In cell adhesion assay, the percent adherences of SACC-83 cells co-cultured with 25 ng/ml NGF at 1.5 hours and 5, 25 ng/ml NGF at 6 hours were significantly higher than that co-cultured with 0 ng/ml NGF (P < .05). However, high concentration of NGF (500 ng/ml) resulted in a significant inhibition of invasion (P < .05). CONCLUSION: Overexpression of NGF and TrkA in human salivary ACC tissues may constitute a reason for perineural invasion in salivary ACC. 相似文献
42.
43.
C Holubarsch G Hasenfuss C Chen R Tarnowska T Bonzel H Just 《Zeitschrift für Kardiologie》1987,76(6):340-345
We analyzed performance and efficiency of the left ventricular myocardium on the basis of two new energetic parameters. The myocardial energy consumed during one cardiac cycle is related to performed work on the one hand (E1) and to the stress-time-integral on the other (E2). E1 was obtained by analysis of the pressure-volume integral divided by left ventricular muscle mass. E2 was obtained as follows: the stress-time integral was analyzed from pressure-volume data and wall thickness using an ellipsoidal calculation model. In order to transfer the stress-time integral into energy units, the value was multiplied by a constant factor which was obtained in experimental myothermal studies. In ten patients with coronary heart disease undergoing diagnostic heart catheterization, angiocardiography was performed before and after oral administration of nitroglycerin (1.6 mg). Total energy consumption (2E1 + E2) per gram myocardium per beat decreased from 6.1 +/- 1.3 mcal/g to 4.7 +/- 1.4 mcal/g (P less than 0.01), and myocardial efficiency (E1/[2E1 + E2]) increased from 27.0 +/- 3.1% to 28.4 +/- 4.3% (N.S.) on the average. This analysis explains quantitatively the beneficial effect of nitro-preparations on myocardial function and energetics. 相似文献
44.
Type IIIC tibial fractures are complex injuries involving extensive bone and soft-tissue devascularization that result in a high percentage of complications and ultimate amputation. An emergency free flap transfer not only may salvage the limb but also may improve the aesthetic and functional results of reconstruction by placing the injured structures in a well-vascularized bed. Two cases of type IIIC tibial fracture were treated in this manner, and we present our experience with a 30-month follow-up of one patient and a 6-month follow-up of another patient. 相似文献
45.
46.
神经肽Y(NPY)是广泛分布于中枢神经系统和外周神经各部位的神经肽类物质。本实验观察NPY在体外对几种免疫细胞活性的直接作用。结果表明,NPY对小鼠T淋巴细胞丝裂原反应性和NK细胞的杀伤活性均无明显影响(P>0.05),对巨噬细胞分泌溶菌酶有明显抑制作用(P<0.05);而对B淋巴细胞丝裂原反应性则有明显的促进作用(P<0.05)。上述结果提示,NPY对部分免疫细胞功能的影响因细胞种类而异。 相似文献
47.
S H Faro A R Turtz R A Koenigsberg F B Mohamed C Y Chen H Stein 《AJNR. American journal of neuroradiology》1997,18(8):1588
The MR imaging features of a paraganglioma of the cauda equina with associated spinal cord cysts are presented. MR imaging showed the tumor to be isointense with the spinal cord on all pulse sequences and to enhance homogeneously. The intramedullary cysts had increased signal intensity on proton density- and T2-weighted images, and involved the cervical and thoracic regions. 相似文献
48.
49.
斑点—酶联免疫吸附试验检测卡氏肺孢子虫 总被引:1,自引:0,他引:1
应用完整的卡氏肺孢子虫包囊作抗原,以4×10^7/ml包裹点样,作斑点-酶联免疫吸附试验检测肺印片卡氏肺孢子虫包囊阳性的BALB/c小鼠血清20份,同时检测包囊阴性的小鼠血清20份,结果除一份小鼠血清IgG阴性反应外,均为阳性反应,阳性率为95%;而正常对照血清全为阴性反应。另外,检测了3份纤支镜刷检物中包囊阳性的病人血清,均为阳性反应;50例健康孕妇血清的检查,抗体阳性率为12%。 相似文献
50.
The granulocyte colony-stimulating factor (G-CSF) has been shown to accelerate recovery from severe neutropenia and to decrease the incidence of documented infections after intensive chemotherapy in cancer patients. However, the routine prophylactic use of G-CSF is expensive. This study was conducted to determine the role of G-CSF as adjunct therapy for septicemia following neutropenia caused by chemotherapy in children with acute leukemia. Fifty consecutive episodes of septicemia were studied involving 34 episodes of Gram-negative, 7 episodes of Gram-positive, 5 episodes of polymicrobial bacterial septicemia, one episode of fungemia, and 3 episodes of disseminated fungal infection. In the first 25 episodes, G-CSF was not used (group A). For the next 16 episodes, G-CSF 200 μg per square meter per day subcutaneously was given immediately after the septicemia was documented until the absolute neutrophil count was maintained at more than 1,500 per cubic millimeter (group B). Thereafter, G-CSF at the same dose as that of group B was prophylactically used in all the children who received high-dose cytosine arablnc-side-containing regimens. Nine episodes of septicemia occurred (group C). The incidences of mortality per episode of septicemia in groups A, B, and C were 12.0% (3/25), 12.5% (2/16) and 0% (0/9), respectively. Statistically, there was no difference between the three groups overall and in pair-wise comparisons (all P > 0.5). The durations of G-CSF administration in group B ranged from 6 to 26 days with a median of 12 days and the durations of G-CSF administration in group C ranged from 10 to 23 days with a median of 19 days. With or without G-CSF, there may be no significant difference in the mortality of septicemia following neutropenia caused by chemotherapy in children with acute leukemia. 相似文献