全文获取类型
收费全文 | 77771篇 |
免费 | 5155篇 |
国内免费 | 336篇 |
专业分类
耳鼻咽喉 | 690篇 |
儿科学 | 2253篇 |
妇产科学 | 1966篇 |
基础医学 | 11166篇 |
口腔科学 | 2446篇 |
临床医学 | 7667篇 |
内科学 | 16623篇 |
皮肤病学 | 1832篇 |
神经病学 | 8220篇 |
特种医学 | 1640篇 |
外科学 | 6654篇 |
综合类 | 501篇 |
一般理论 | 79篇 |
预防医学 | 9183篇 |
眼科学 | 1125篇 |
药学 | 5449篇 |
中国医学 | 270篇 |
肿瘤学 | 5498篇 |
出版年
2024年 | 100篇 |
2023年 | 1004篇 |
2022年 | 1912篇 |
2021年 | 3580篇 |
2020年 | 2121篇 |
2019年 | 2956篇 |
2018年 | 3497篇 |
2017年 | 2312篇 |
2016年 | 2444篇 |
2015年 | 2811篇 |
2014年 | 3541篇 |
2013年 | 4488篇 |
2012年 | 7045篇 |
2011年 | 7170篇 |
2010年 | 3591篇 |
2009年 | 3108篇 |
2008年 | 5012篇 |
2007年 | 4931篇 |
2006年 | 4525篇 |
2005年 | 4104篇 |
2004年 | 3620篇 |
2003年 | 3152篇 |
2002年 | 2713篇 |
2001年 | 298篇 |
2000年 | 203篇 |
1999年 | 298篇 |
1998年 | 478篇 |
1997年 | 387篇 |
1996年 | 291篇 |
1995年 | 237篇 |
1994年 | 189篇 |
1993年 | 165篇 |
1992年 | 112篇 |
1991年 | 92篇 |
1990年 | 78篇 |
1989年 | 76篇 |
1988年 | 65篇 |
1987年 | 51篇 |
1986年 | 51篇 |
1985年 | 45篇 |
1984年 | 58篇 |
1983年 | 56篇 |
1982年 | 48篇 |
1981年 | 50篇 |
1980年 | 41篇 |
1979年 | 21篇 |
1978年 | 19篇 |
1977年 | 22篇 |
1976年 | 14篇 |
1975年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Zagra Antonino Scaramuzzo Laura Galbusera Fabio Minoia Leone Archetti Marino Giudici Fabrizio 《European spine journal》2015,24(7):924-930
Introduction
Aim of the study was to evaluate the biomechanical stability and the clinical efficacy of a lumbar interbody fusion obtained by single oblique cage implanted by a posterior approach.Method
Through the realization of three finite element models (FEMs), the biomechanics of POLIF was compared to PLIF and TLIF. Ninety-four patients underwent interbody fusion by POLIF with instrumented posterolateral fusion. Clinical and radiographic outcomes were evaluated at regular intervals for at least 6 months.Results
The FEMs showed no statistically significant differences in stability in compression and flexion–extension. Mean preoperative VAS score was 7.1, decreased to 2.1 at follow-up. Mean preoperative SF-12 value was 34.5 %, increased to 75.4 % at follow-up. All patients showed a good fusion rate and no hardware failure.Discussion
POLIF associated to instrumented posterolateral fusion is a viable and safe surgical technique, which ensures a biomechanical stability similar to other surgical techniques.992.
993.
994.
995.
996.
997.
Brandão Rondon MU Alves MJ Braga AM Teixeira OT Barretto AC Krieger EM Negrão CE 《Journal of the American College of Cardiology》2002,39(4):676-682
OBJECTIVES: We sought to study: 1) the impact of hemodynamic and left ventricular function on short-term postexercise blood pressure reduction in elderly hypertensive patients; and 2) the 22-h postexercise effects on ambulatory blood pressure in elderly hypertensive patients. BACKGROUND: Although early exercise provokes postexercise blood pressure reduction, the mechanisms underlying this response are not completely understood. Besides, it is unclear whether the reduction in blood pressure after exercise lasts long enough to have clinical relevance in elderly hypertensive patients. METHODS: We studied 24 elderly hypertensive patients (age 68.9 +/- 1.5 years) and 18 age-matched normotensive control subjects (age 68.1 +/- 1.2 years). Cardiac output (carbon dioxide rebreathing) and blood pressure (auscultatory) were measured at rest and after a 45-min period of low-intensity bicycle exercise (50% maximal oxygen uptake) and at 15, 30, 60 and 90 min after exercise. Left ventricular function (by Doppler echocardiography) was also evaluated. Ambulatory blood pressure monitoring was evaluated after 45 min of exercise or 45 min of rest, in a randomized order. RESULTS: In the hypertensive patients, exercise provoked a significant reduction in blood pressure, cardiac output, stroke volume and left ventricular end-diastolic volume. It also provoked a significant reduction in systolic, mean and diastolic blood pressure during a 22-h period, at daytime and nighttime. CONCLUSIONS: The short-term reduction in blood pressure after exercise in elderly hypertensive patients is associated with a decrease in stroke volume and left ventricular end-diastolic volume. The 22-h postexercise reduction in blood pressure demonstrates the clinical relevance of low-intensity exercise in elderly hypertensive patients. 相似文献
998.
Ana Maria Ferreira Alvaro Diaz Cecilia Fernandez & Robert B. Sim 《Parasite immunology》2001,23(12):655-658
The larval stage of the parasite Echinococcus granulosus causes hydatid disease. The hydatid cyst is potentially capable of activating host complement, since it is a large, persistent, carbohydrate-rich structure, coated with host immunoglobulins, and localized in the host's internal organs. Nonetheless, in vitro studies have suggested that the cyst surface, the hydatid cyst wall (HCW), is a poor complement activator. In this study, we assessed the occurrence of in vivo complement activation on the hydatid cyst by measuring the levels of two complement activation products, C3d and complexes bearing a C9 activation neoepitope (TCC/MAC), in extracts from HCW of human origin. Low amounts of C3d and TCC/MAC were found in HCW in comparison with their levels in normal human plasma and activated human sera, suggesting that in vivo complement activation on HCW is efficiently down-regulated. This regulation may contribute to limit host inflammation which has been observed to correlate with parasite degeneration and death. 相似文献
999.
Hodgkin and Reed-Sternberg cells harbor alterations in the major tumor suppressor pathways and cell-cycle checkpoints: analyses using tissue microarrays 总被引:10,自引:6,他引:10
García JF Camacho FI Morente M Fraga M Montalbán C Alvaro T Bellas C Castaño A Díez A Flores T Martin C Martinez MA Mazorra F Menárguez J Mestre MJ Mollejo M Sáez AI Sánchez L Piris MA;Spanish Hodgkin Lymphoma Study Group 《Blood》2003,101(2):681-689
Tumoral cells in Hodgkin lymphoma (HL) display an increased growth fraction and diminished apoptosis, implying a profound disturbance of the cell cycle and apoptosis regulation. However, limitations of molecular techniques have prevented the analysis of the tumor suppressor pathways and cell-cycle checkpoints. Tissue microarray (TMA) is a powerful tool for analyzing a large number of molecular variables in a large series of tumors, although the feasibility of this technique has not yet been demonstrated in heterogeneous tumors. The expression of 29 genes regulating the cell cycle and apoptosis were analyzed by immunohistochemistry and in situ hybridization in 288 HL biopsies using TMA. The sensitivity of the technique was validated by comparing the results with those obtained in standard tissue sections. The results revealed multiple alterations in different pathways and checkpoints, including G1/S and G2/M transition and apoptosis. Striking findings were the overexpression of cyclin E, CDK2, CDK6, STAT3, Hdm2, Bcl2, Bcl-X(L), survivin, and NF-kappaB proteins. A multiparametric analysis identified proteins associated with increased growth fraction (Hdm2, p53, p21, Rb, cyclins A, B1, D3, and E, CDK2, CDK6, SKP2, Bcl-X(L), survivin, STAT1, and STAT3), and proteins associated with apoptosis (NF-kappaB, STAT1, and RB). The analysis also demonstrated that Epstein-Barr virus (EBV)-positive cases displayed a characteristic profile, confirming the pathogenic role of EBV in HL. Survival probability depends on multiple biologic factors, including overexpression of Bcl2, p53, Bax, Bcl-X(L), MIB1, and apoptotic index. In conclusion, Hodgkin and Reed-Sternberg cells harbor concurrent and overlapping alterations in the major tumor suppressor pathways and cell-cycle checkpoints. This appears to determine the viability of the tumoral cells and the clinical outcome. 相似文献
1000.
Monika Dobrzyska-Mizera Monika Knitter Salvatore Mallardo Maria Cristina Del Barone Gabriella Santagata Maria Laura Di Lorenzo 《Materials》2021,14(10)
Bio-based composites made of poly(L-lactic acid) (PLLA) and β-cyclodextrin/d-limonene inclusion complex (CD-Lim) were prepared by melt extrusion. Encapsulation of volatile d-limonene molecules within β-cyclodextrin cages was proven to be a successful strategy to prevent evaporation during high-temperature processing. However, small amounts of limonene were released upon processing, resulting in the plasticization of the polymeric matrix. Morphological analysis revealed good dispersion of the filler, which acted as a nucleating agent, favoring the growth of PLLA crystals. The composites′ lowered glass transition temperature upon the addition of CD-Lim was also proved by thermomechanical analysis (DMA). Moreover, DMA revealed constant stiffness of modified materials at room temperature, which is crucial in PLLA-based formulations. 相似文献