全文获取类型
收费全文 | 6472篇 |
免费 | 392篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 113篇 |
儿科学 | 193篇 |
妇产科学 | 141篇 |
基础医学 | 891篇 |
口腔科学 | 118篇 |
临床医学 | 624篇 |
内科学 | 1360篇 |
皮肤病学 | 90篇 |
神经病学 | 467篇 |
特种医学 | 369篇 |
外科学 | 1212篇 |
综合类 | 29篇 |
一般理论 | 1篇 |
预防医学 | 374篇 |
眼科学 | 192篇 |
药学 | 369篇 |
中国医学 | 15篇 |
肿瘤学 | 335篇 |
出版年
2023年 | 53篇 |
2022年 | 143篇 |
2021年 | 242篇 |
2020年 | 119篇 |
2019年 | 175篇 |
2018年 | 188篇 |
2017年 | 136篇 |
2016年 | 170篇 |
2015年 | 186篇 |
2014年 | 232篇 |
2013年 | 298篇 |
2012年 | 413篇 |
2011年 | 396篇 |
2010年 | 249篇 |
2009年 | 215篇 |
2008年 | 292篇 |
2007年 | 295篇 |
2006年 | 296篇 |
2005年 | 290篇 |
2004年 | 253篇 |
2003年 | 238篇 |
2002年 | 218篇 |
2001年 | 142篇 |
2000年 | 125篇 |
1999年 | 112篇 |
1998年 | 65篇 |
1997年 | 48篇 |
1996年 | 26篇 |
1995年 | 33篇 |
1994年 | 30篇 |
1992年 | 80篇 |
1991年 | 65篇 |
1990年 | 84篇 |
1989年 | 64篇 |
1988年 | 57篇 |
1987年 | 53篇 |
1986年 | 45篇 |
1985年 | 70篇 |
1984年 | 38篇 |
1983年 | 39篇 |
1982年 | 47篇 |
1979年 | 44篇 |
1978年 | 25篇 |
1977年 | 26篇 |
1975年 | 33篇 |
1974年 | 33篇 |
1973年 | 35篇 |
1972年 | 32篇 |
1971年 | 27篇 |
1968年 | 25篇 |
排序方式: 共有6893条查询结果,搜索用时 0 毫秒
91.
Karla Sofía Snchez-Zambrano Marina Hernndez-Resndiz Cristian Gmez-Rodríguez Linda Viviana García-Quionez Josu Amilcar Aguilar-Martínez Edn Amaral Rodríguez-Castellanos Luis Felipe Verdeja Daniel Fernndez-Gonzlez Guadalupe Alan Castillo-Rodríguez 《Materials》2022,15(9)
In this work, we studied the phases in a Mg-Ti-O system using a 1:1 formulation of MgO:TiO2, mixing synthetic brucite of Mexican origin with TiO2 microparticles of high purity, with a heat treatment at 1100 °C for 1 h. Due to its valence electrons, TiO2 can contribute to the sintering process to improve density in MgO products. The raw materials and formulation by XPS and X-RD techniques were characterized. The results demonstrate the presence of different oxidation states in titania and the formation of different oxides in the Mg-Ti-O system when mixed and calcined at 1100 °C; additionally, we estimated the formation of vacancies in the crystal lattice during the transformation from hexagonal brucite to magnesia with a cubic structure centered on the faces. Its thermal behavior is indicated by the MgO-TiO2 phase diagram. 相似文献
92.
93.
Anja Lazi Miodrag Koci Neboja Trajkovi Cristian Popa Leonardo Alexandre Peyr-Tartaruga Johnny Padulo 《Nutrients》2022,14(9)
Caffeine supplementation has become increasingly popular among athletes. The benefits of caffeine include delaying the negative effects of fatigue, maintaining a high level of physical and mental performance, and improving certain abilities necessary for sport success. Given the complex nature of basketball, caffeine could be a legal, ergogenic stimulant substance, which will positively affect overall basketball performance. The purpose of this systematic review was to summarize evidence for the effect of acute caffeine ingestion on variables related to the basketball performance. Web of Science, PubMed, Scopus and ProQuest, MEDLINE, and ERIC databases were searched up to February 2021. Studies that measured the acute effect of caffeine on basketball performance were included and analyzed. Eight studies published between 2000 and 2021 were included in the analysis. Pre-exercise caffeine intake increased vertical jump height, running time at 10 and 20 m without the ball, overall basketball performance (number of body impacts, number of free throws, rebounds, and assists) during simulated games, and reduced the time required to perform a basketball-specific agility test. Equivocal results between caffeine and placebo groups were found for aerobic capacity, free throw and three-point accuracy, and dribbling speed. Pre-exercise caffeine ingestion did not affect RPE, but insomnia and urinary excretion were increased. The pre-exercise ingestion of 3 and 6 mg/kg caffeine was found to be effective in increasing several physical performance variables in basketball players during sport-specific testing and simulated matches. However, considering the intermittent nature and complexity of basketball, and individual differences between players, future studies are needed. 相似文献
94.
95.
96.
Cristian Tomasetti Bert Vogelstein Giovanni Parmigiani 《Proceedings of the National Academy of Sciences of the United States of America》2013,110(6):1999-2004
Although it has been hypothesized that some of the somatic mutations found in tumors may occur before tumor initiation, there is little experimental or conceptual data on this topic. To gain insights into this fundamental issue, we formulated a mathematical model for the evolution of somatic mutations in which all relevant phases of a tissue’s history are considered. The model makes the prediction, validated by our empirical findings, that the number of somatic mutations in tumors of self-renewing tissues is positively correlated with the age of the patient at diagnosis. Importantly, our analysis indicates that half or more of the somatic mutations in certain tumors of self-renewing tissues occur before the onset of neoplasia. The model also provides a unique way to estimate the in vivo tissue-specific somatic mutation rates in normal tissues directly from the sequencing data of tumors. Our results have substantial implications for the interpretation of the large number of genome-wide cancer studies now being undertaken. 相似文献
97.
Kristopher Gerardi Lorenz Goette Stephan Meier 《Proceedings of the National Academy of Sciences of the United States of America》2013,110(28):11267-11271
Unprecedented levels of US subprime mortgage defaults precipitated a severe global financial crisis in late 2008, plunging much of the industrialized world into a deep recession. However, the fundamental reasons for why US mortgages defaulted at such spectacular rates remain largely unknown. This paper presents empirical evidence showing that the ability to perform basic mathematical calculations is negatively associated with the propensity to default on one’s mortgage. We measure several aspects of financial literacy and cognitive ability in a survey of subprime mortgage borrowers who took out loans in 2006 and 2007, and match them to objective, detailed administrative data on mortgage characteristics and payment histories. The relationship between numerical ability and mortgage default is robust to controlling for a broad set of sociodemographic variables, and is not driven by other aspects of cognitive ability. We find no support for the hypothesis that numerical ability impacts mortgage outcomes through the choice of the mortgage contract. Rather, our results suggest that individuals with limited numerical ability default on their mortgage due to behavior unrelated to the initial choice of their mortgage. 相似文献
98.
99.
ABSTRACT This paper presents a control strategy that compensates for the nonlinearity in the inexpensive sensors and hardware of a cost effective prosthetic hand. The control strategy uses neural network-based force control and sensory feedback to detect disturbance induced by slippage. The neural network approach is chosen over other nonlinear models because it is easy to implement and it offered the additional advantage of having its parameters easily adjusted over the life span of the device. The proposed strategy was evaluated on a functional multi-digit underactuated prosthetic hand. The initial and incremental forces exerted from each finger were adjusted to balance the amount of disturbance and the deformation of the objects. Experiments were conducted to test the performance of the protocol in situations encountered in activities of daily living. The displacement of each object under three grasping configurations was measured as a performance criterion while the object's mass was changed. The results showed that with the adjusted parameters for each grasping configuration, the control strategy was able to detect the dynamic changes in mass of the object and was also able to successfully adjust the grasping force before the object drops from the hand. 相似文献
100.
Stefano Terzoni Emanuele Montanari Cristina Mora Cristian Ricci Anne Lucie Destrebecq 《International Journal of Urological Nursing》2013,7(3):121-125
Nurses use several conservative methods for treating urinary incontinence after radical prostatectomy. Functional electrical stimulation (FES) has a recognized role, while extracorporeal magnetic innervation (ExMI) is still under evaluation in the international guidelines. Few data are available in literature, regarding comparisons between these two treatments. The aim of the study is to compare electrical stimulation and magnetic innervation for treating urinary incontinence after radical prostatectomy. Twenty‐two patients treated with ExMI and 18 treated with FES were enrolled in a retrospective study. ExMI was available for 6 weeks; the number of times ExMI was required by the patients to reduce their leakages to 10 g/d or less was compared. The groups had comparable age and body mass index. Initial leakages showed clinically relevant differences (median = 80 g/d in the ExMI patients and 150 g/d in the FES group). After 6 weeks, 71·9% of ExMI patients and 29·2% of FES patients had completed rehabilitation. The difference was statistically significant even after adjusting the analyses for initial leakages (p = 0·008). Six patients treated with ExMI had already undergone FES, with no clinically relevant results after five sessions (leakages reduction <50 g/d). The difference remained even after removing the data of these patients from the analysis (p = 0·004). Both FES and ExMI produce muscle strengthening, which is just one step of rehabilitation. Our findings suggest the possibility of using ExMI instead of FES to reduce the times required to improve muscular performance. Pelvic muscle exercises remain essential to develop the ability to automatically perform the contractions needed to avoid leakages. 相似文献