全文获取类型
收费全文 | 2412篇 |
免费 | 94篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 41篇 |
儿科学 | 114篇 |
妇产科学 | 139篇 |
基础医学 | 315篇 |
口腔科学 | 41篇 |
临床医学 | 140篇 |
内科学 | 463篇 |
皮肤病学 | 62篇 |
神经病学 | 204篇 |
特种医学 | 51篇 |
外科学 | 142篇 |
综合类 | 14篇 |
一般理论 | 1篇 |
预防医学 | 245篇 |
眼科学 | 127篇 |
药学 | 271篇 |
中国医学 | 2篇 |
肿瘤学 | 150篇 |
出版年
2024年 | 2篇 |
2023年 | 18篇 |
2022年 | 88篇 |
2021年 | 119篇 |
2020年 | 41篇 |
2019年 | 58篇 |
2018年 | 71篇 |
2017年 | 54篇 |
2016年 | 63篇 |
2015年 | 83篇 |
2014年 | 102篇 |
2013年 | 126篇 |
2012年 | 211篇 |
2011年 | 210篇 |
2010年 | 110篇 |
2009年 | 93篇 |
2008年 | 144篇 |
2007年 | 123篇 |
2006年 | 155篇 |
2005年 | 153篇 |
2004年 | 150篇 |
2003年 | 125篇 |
2002年 | 117篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 14篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1985年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 6篇 |
1965年 | 6篇 |
1964年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有2522条查询结果,搜索用时 15 毫秒
111.
Kevin Lüthy Birgit Ahrens Shilpa Rawal Zhiyuan Lu Dorota Tarnogorska Ian A. Meinertzhagen 《Journal of neurogenetics》2014,28(3-4):291-301
Each neuropil module, or cartridge, in the fly's lamina has a fixed complement of cells. Of five types of monopolar cell interneurons, only L4 has collaterals that invade neighboring cartridges. In the proximal lamina, these collaterals form reciprocal synapses with both the L2 of their own cartridge and the L4 collateral branches from two other neighboring cartridges. During synaptogenesis, L4 collaterals strongly express the cell adhesion protein Kirre, a member of the irre cell recognition module (IRM) group of proteins (, J Neurogenet, 23, 48–67). The authors show by mutant analysis and gene knockdown techniques that L4 neurons develop their lamina collaterals in the absence of this cell adhesion protein. Using electron microscopy (EM), the authors demonstrate, however, that without Kirre protein these L4 collaterals selectively form fewer synapses. The collaterals of L4 neurons of various genotypes reconstructed from serial-section EM revealed that the number of postsynaptic sites was dramatically reduced in the absence of Kirre, almost eliminating any synaptic input to L4 neurons. A significant reduction of presynaptic sites was also detected in kirre0 mutants and gene knockdown flies using RNA interference. L4 neuron reciprocal synapses are thus almost eliminated. A presynaptic marker, Brp-shortGFP confirmed these data using confocal microscopy. This study reveals that removing Kirre protein specifically disrupts the functional L4 synaptic network in the Drosophila lamina. 相似文献
112.
Dorota Diakowska Krystyna Markocka-M?czka Miros?aw Nienartowicz Andrzej Lewandowski Krzysztof Grabowski 《Archives of Medical Science》2014,10(5):956-961
Introduction
Prostaglandin-2 (PGE-2), one of the products of cyclooxygenase-2 (COX-2) induced catalysis, may play a critical role in the carcinogenesis of esophageal squamous cell carcinoma (ESCC). We investigated the efficacy of using serum PGE-2 concentration as a biomarker for this cancer type.Material and methods
Prostaglandin-2 levels were analyzed in the serum of 65 ESCC patients and in 47 healthy individuals. The concentrations of cyclooxygenase-2 (COX-2) were measured in tumor tissues and normal tissues obtained from 31 surgically treated ESCC patients.Results
Serum PGE-2 concentration was significantly higher in ESCC patients than in control patients (p = 0.004), especially in the early stages (I + II) of cancer (p < 0.0001). We observed significant inverse relationships between serum PGE-2 levels and: tumor stage, primary tumor progression, lymph and distant metastasis. The COX-2 concentration was significantly elevated in tumors as compared to normal tissues (p = 0.008). A significant correlation between serum PGE-2 and tumor COX-2 was observed (rho = 0.46, p = 0.009). However, ROC analysis showed that serum PGE-2 may be a weak prognostic factor for ESCC.Conclusions
Our results suggest that an elevated concentration of serum PGE-2 in the early stages of cancer may possibly be associated with tumor initiation and cancer development in ESCC. The exact role of these findings in early detection of this highly lethal cancer requires further research. 相似文献113.
Teresa oek Muge Qile Pawe Ka
mierczak Meye Bloothooft Marcel A. G. van der Heyden Dorota Maciejewska 《RSC advances》2019,9(66):38355
This work presents drug-likeness and the cardiotoxicity profiles of six potent pentamidine analogs 1–6 and three new compounds 7–9 as chemotherapeutics for therapy of Pneumocystis jiroveci pneumonia. A combination of experimental and computational approaches was used in the cardiotoxicity examination. The hERG trafficking and functionality of the hERG currents were tested by western blot analyses, immunofluorescent staining procedures, and patch-clamp electrophysiological assays. Cardiotoxicity combined with blocking the hERG K+ channel was predicted, and then simulated by docking to the CSM-TM model 732 protein. Location of pentamidines in the proximity of Leu622, Thr623, Ser649, Tyr652, Ala653, and Phe656, and the high energies of interactions were in accordance with probable blocking of the hERG channel. However, in the biochemical experiments, no significant changes in IhERG densities and a minor effect on hERG maturation were observed. Predicted metabolic transformation of pentamidines with S atoms in the aliphatic linker leads to oxidation of one S atom, but those with the phenyl sulfanilide moiety can be oxidized to chinones. The tested pentamidines characterized by the presence of sulfur atoms or sulfanilide groups, have favorable drug-likeness parameters and are promising lead structures in the development of new potent chemotherapeutics against PJP.The pentamidines with S atoms or sulfanilide groups in the linker have favorable drug-likeness parameters and low toxicity. 相似文献
114.
Young adulthood is the period from the late teens through the twenties and is associated with life transitions that could contribute to the development of obesity. Targeting this group will be critical to reversing the obesity epidemic. The aim of the study was to investigate the eating behaviors and lifestyle of healthcare students in Poland. We enrolled 227 students in the study. Convenience sampling was employed. Diet (Food Frequency Questionnaire), physical activity (International Physical Activity Questionnaire), depressive symptoms (Beck Depression Inventory), impulsivity (Barratt Impulsivity Scale), and eating behaviors (Three-Factor Eating Questionnaire) were assessed. One in three students exhibited depressive symptoms, one in four showed low levels of physical activity. More than 40% of the students did not consume vegetables at least once a day, and more than half did not consume fruit. Only approximately 50% of the students ate fish several times a month. There was an association between high scores of specific eating behaviors and body weight, adherence to the Mediterranean diet, and consumption of specific product groups (sweets, alcohol). The results of our study are expected to contribute to a better understanding of dietary habits and overweight/obesity in university students, and support the development of programs to promote healthy lifestyles in that population. 相似文献
115.
The evidence for abandoning the amniotic fluid index in favor of the single deepest pocket 总被引:3,自引:0,他引:3
Magann EF Chauhan SP Doherty DA Magann MI Morrison JC 《American journal of perinatology》2007,24(9):549-555
This study assessed whether the amniotic fluid index (AFI) or the single deepest pocket (SDP) is the best technique to estimate amniotic fluid volume. The AFI and SDP were compared to a dye-determined or directly measured amniotic fluid volume. A PUBMED search from 1990 to 2006 was conducted using the search terms "single deepest pocket" or "largest vertical pocket" or "maximum vertical pocket" or "2X1 pocket" AND "amniotic fluid index". One study compared the AFI and SDP to a dye-determined amniotic fluid volume. There were 1219 publications that used the search term SDP-LVP-MVP versus 4378 using AFI. Twenty publications contained both the AFI and SDP, but only six compared the AFI and SDP. Both the AFI and the SDP poorly identified abnormal amniotic fluid volumes, and neither technique was superior to the other. The AFI identifies a significantly greater number of women as having oligohydramnios versus the SDP but without any difference in perinatal outcomes. Compared with SDP, AFI excessively characterizes a greater number of pregnancies as having oligohydramnios leading to more interventions without improvement in perinatal outcome. The AFI should be abandoned and the SDP used to estimate amniotic fluid volume. 相似文献
116.
DNA adducts, one of genetic damages markers, precede and finally can lead to oncogenic mutations. They appear in genome as a result of DNA bases damages caused by various and numerous environmental factors eg. ultraviolet light, ionic radiation, toxins and also endogenic substances, for example estrogens. It is believed that the creation of DNA adducts is a necessary but insufficient process for the neoplastic transformation of the cell. The following review presents concise knowledge about the DNA adducts creation and their sequels served in healthy and cancerous tissues of the female genital organs, on the base of the available data. 相似文献
117.
118.
Lung cancer is one of the most common neoplasms globally, with about 2.2 million new cases and 1.8 million deaths annually. Although the most important factor in reducing lung cancer risk is lifestyle change, most patients favour the use of supplements, for example, rather than quitting smoking or following a healthy diet. To better understand the efficacy of such interventions, a systematic review was performed of data from randomized controlled trials concerning the influence of beta-carotene supplementation on lung cancer risk in subjects with no lung cancer before the intervention. The search corpus comprised a number of databases and eight studies involving 167,141 participants, published by November 2021. The findings indicate that beta-carotene supplementation was associated with an increased risk of lung cancer (RR = 1.16, 95% CI = 1.06–1.26). This effect was even more noticeable among smokers and asbestos workers (RR = 1.21, 95% CI = 1.08–1.35) and non-medics (RR = 1.18, 95% CI = 1.07–1.29). A meta-regression found no relationship between the beta-carotene supplementation dose and the size of the negative effect associated with lung cancer risk. Our findings indicate that beta-carotene supplementation has no effect on lung cancer risk. Moreover, when used as the primary chemoprevention, beta-carotene may, in fact, increase the risk of lung cancer. 相似文献
119.
Magdalena Dudek Bartomiej Lis Ryszard Kluczowski Mariusz Krauz Magdalena Zibka Marcin Gajek Alicja Rapacz-Kmita Micha Mosiaek Piotr Dudek Dorota Majda Andrzej Ra
niak 《Materials》2022,15(7)
The development of new chemically resistant anodes for protonic ceramic fuel cells (PCFCs) is urgently required to avoid the costly deep hydrogen purification method. Ba0.95Ca0.05Ce0.9Y0.1O3−δ (5CBCY), which is more chemically resistant than BaCaCe0.9Y0.1O3−δ, was here tested as a component of a composite NiO–5CBCY anode material. A preparation slurry comprising 5CBCY, NiO, graphite, and an organic medium was tape cast, sintered and subjected to thermal treatment in 10 vol.% H2 in Ar at 700 °C. Differential thermal analysis, thermogravimetry, quadrupole mass spectrometry, X-ray diffraction analysis, scanning electron microscopy, the AC four-probe method and electrochemical impedance spectroscopy were used for the investigation. The electrical conductivity of the Ni–5CBCY in H2–Ar at 700 °C was 1.1 S/cm. In the same gas atmosphere but with an additional 5 vol.% CO2, it was slightly lower, at 0.8 S/cm. The Ni–5CBCY cermet exhibited repeatable electrical conductivity values during Ni-to-NiO oxidation cycles and NiO-to-Ni reduction in the 5CBCY matrix, making it sufficient for preliminary testing in PCFCs. 相似文献
120.
The Covid-19 pandemic caused lockdown of economies, which in turn led to the worsening of the economic situation of many households. During the first wave of the Covid-19 pandemic governments undertook various measures to support economies and societies, including jobs protection along with financial support provision to people who suffered financial loss during the economic crisis. We analyse the economic situation of older Europeans, depending on their socio-economic status as well as country of residence characteristics, including economic and labour market changes during the first phase of the pandemic, the strictness of government policies but also the country development level using the Human Development Index. We use the results of the Survey of Health, Ageing, and Retirement in Europe (SHARE), including the SHARE Corona Telephone Survey, which was conducted during the first wave of the Covid-19 pandemic. Our results indicate that individual characteristics have a higher impact on individual economic stress, compared to country characteristics. However, country’s response to the consequences of the Covid-19 pandemic, but also the overall level of development influences the economic situation and ability to cope with the economic risks people aged 50 and over face. People in more developed countries have smaller difficulties in making ends meet, while the economic crisis and more stringent policies reduce chances to receive financial support and increase economic risks. 相似文献