全文获取类型
收费全文 | 1609篇 |
免费 | 129篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 21篇 |
妇产科学 | 18篇 |
基础医学 | 258篇 |
口腔科学 | 16篇 |
临床医学 | 195篇 |
内科学 | 263篇 |
皮肤病学 | 19篇 |
神经病学 | 110篇 |
特种医学 | 96篇 |
外科学 | 264篇 |
综合类 | 10篇 |
预防医学 | 106篇 |
眼科学 | 28篇 |
药学 | 110篇 |
中国医学 | 7篇 |
肿瘤学 | 192篇 |
出版年
2024年 | 3篇 |
2023年 | 19篇 |
2022年 | 45篇 |
2021年 | 85篇 |
2020年 | 34篇 |
2019年 | 63篇 |
2018年 | 63篇 |
2017年 | 39篇 |
2016年 | 39篇 |
2015年 | 46篇 |
2014年 | 64篇 |
2013年 | 78篇 |
2012年 | 119篇 |
2011年 | 108篇 |
2010年 | 56篇 |
2009年 | 61篇 |
2008年 | 77篇 |
2007年 | 89篇 |
2006年 | 79篇 |
2005年 | 74篇 |
2004年 | 71篇 |
2003年 | 59篇 |
2002年 | 46篇 |
2001年 | 44篇 |
2000年 | 35篇 |
1999年 | 40篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 20篇 |
1991年 | 14篇 |
1990年 | 18篇 |
1989年 | 17篇 |
1988年 | 20篇 |
1987年 | 5篇 |
1986年 | 11篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1974年 | 4篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1969年 | 4篇 |
1968年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有1740条查询结果,搜索用时 15 毫秒
71.
Slow‐flow and no‐reflow phenomenon are taken to sudden loss of coronary artery flow, typically after stenting or angioplasty in primary PCI. Otherwise conventional therapy, we report a technique, which autologous blood into intracoronary to supply oxygen and break process thrombosis results in successfully management no‐reflow in primary PCI in ACS. 相似文献
72.
Thi Le Anh Nguyen Thi Hoai Nam Doan Dinh Hieu Truong Nguyen Thi Ai Nhung Duong Tuan Quang Dorra Khiri Sonia Taamalli Florent Louis Abderrahman El Bakali Duy Quang Dao 《RSC advances》2021,11(35):21433
Antioxidant and UV absorption activities of three aaptamine derivatives including piperidine[3,2-b]demethyl(oxy)aaptamine (C1), 9-amino-2-ethoxy-8-methoxy-3H-benzo[de][1,6]naphthyridine-3-one (C2), and 2-(sec-butyl)-7,8-dimethoxybenzo[de]imidazo[4,5,1-ij][1,6]-naphthyridin-10(9H)-one (C3) were theoretically studied by density functional theory (DFT). Direct antioxidant activities of C1–C3 were firstly evaluated via their intrinsic thermochemical properties and the radical scavenging activity of the potential antioxidants with the HOO˙/HO˙ radicals via four mechanisms, including: hydrogen atom transfer (HAT), single electron transfer (SET), proton loss (PL) and radical adduct formation (RAF). Kinetic calculation reveals that HOO˙ scavenging in water occurs via HAT mechanism with C1 (kapp, 7.13 × 106 M−1 s−1) while RAF is more dominant with C2 (kapp, 1.40 × 105 M−1 s−1) and C3 (kapp, 2.90 × 105 M−1 s−1). Antioxidant activity of aaptamine derivatives can be classified as C1 > C3 > C2. Indirect antioxidant properties based on Cu(i) and Cu(ii) ions chelating activity were also investigated in aqueous phase. All three studied compounds show spontaneous and favorable Cu(i) ion chelating activity with ΔG0 being −15.4, −13.7, and −15.7 kcal mol−1, whereas ΔG0 for Cu(ii) chelation are −10.4, −10.8, and −2.2 kcal mol−1 for C1, C2 and C3, respectively. In addition, all compounds show UVA and UVB absorption; in which the excitations are determined mostly as π–π* transition. Overall, the results suggest the potential applications of the aaptamines in pharmaceutics and cosmetics, i.e. as a sunscreen and antioxidant ingredient.Antioxidant and UV absorption activities of three aaptamine derivatives were theoretically studied by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). 相似文献
73.
Quorum sensing is a well-known term for describing bacterial cell–cell communication. Bacteria use quorum sensing pathways to respond to external factors such as nutrient availability, defense mechanisms, and coordinate host toxic behaviors such as biofilm formation, virulence production, and other pathogenesis. Discovery of novel compounds which inhibit quorum sensing without being antibiotic are currently emerging fields. Herein, the library of fifteen benzo[d]thiazole/quinoline-2-thiol bearing 2-oxo-2-substituted-phenylethan-1-yl compounds was designed, synthesized and evaluated to find novel quorum sensing inhibitors. Firstly, compounds were evaluated for their growth inhibitory activities at high concentrations up to 1000 μg mL−1 toward Pseudomonas aeruginosa. Under our conditions, twelve compounds showed moderate growth inhibitory activities in the concentration tested. To our delight, three compounds 3, 6 and 7 do not affect the growth of the bacteria which were chosen for the evaluation of quorum sensing inhibitor activities. In the LasB system, our compounds 3, 6, 7 showed promising quorum-sensing inhibitors with IC50 of 115.2 μg mL−1, 182.2 μg mL−1 and 45.5 μg mL−1, respectively. In the PqsR system, no activity observed suggesting that the selectivity of the compound toward the LasB system. In addition, 7 showed the moderate anti-biofilm formation of Pseudomonas aeruginosa. Docking studies revealed that 3, 6 and 7 binding to the active site of Pseudomonas aeruginosa quorum sensing LasR system with better affinity compared to reference compounds 4-NPO. Finally, computation calculations suggest that compounds are a good template for further drug development.Benzo[d]thiazole-2-thiol bearing 2-oxo-2-substituted-phenylethan-1-yl as potent selective lasB quorum sensing inhibitors and anti-biofilm formation of Pseudomonas aeruginosa. 相似文献
74.
75.
Nghiem Nguyet Thu Truong Tuyet Mai Tran Th໋ Thu Trang Nguyen Anh Tuan Tran Chau Quyen Nguyen Lien Hanh Nguyen Huu Hoan Bui Thi Huong Lan Phung Thi Hau Ha Huy Tue Truong Viet Dung Ryohei Tsuji Yuta Watanabe Naoki Yamamoto Osamu Kanauchi 《Nutrients》2022,14(3)
Lactococcus lactis strain Plasma (LC-Plasma) is reported to have anti-viral effects via direct activation of plasmacytoid dendritic cells, which upregulate the production of type I and III interferons. A randomized, placebo-controlled, double-blind, parallel group study was designed for elementary schoolchildren, grades 1 to 3, in Vietnam. LC-Plasma or a control were administered to schoolchildren as a beverage (1.0 × 1011 count LC-Plasma/day/person). The primary endpoint was to determine the efficacy of LC-Plasma in reducing the cumulative days absent from school due to upper respiratory disease (URID) and gastrointestinal disease (GID), and the secondary endpoint was to evaluate the potency of LC-Plasma on URID/GID symptoms and general well-being scores. LC-Plasma intake significantly reduced the cumulative days absent from school due to URID/GID (Odds ratio (OR) = 0.57, p = 0.004) and URID alone (OR = 0.56, p = 0.005); LC-Plasma also significantly reduced the number of cumulative fever positive days during the first 4 weeks of intervention (OR = 0.58, p = 0.001) and cumulative days with diarrhea during the last 4 weeks of the intervention period (OR = 0.78, p = 0.01). The number of positive general wellbeing days was significantly improved in the LC-Plasma group compared with the control throughout the intervention period (OR = 0.93, 0.93, p = 0.03, 0.04 in the first and last 4 weeks of the intervention, respectively). These data suggest that LC-Plasma seems to improve the health condition of elementary schoolchildren and reduces school absenteeism due to infectious disease, especially URID. 相似文献
76.
77.
78.
Dinh Hieu Truong Thi Chinh Ngo Nguyen Thi Ai Nhung Duong Tuan Quang Thi Le Anh Nguyen Dorra Khiri Sonia Taamalli Florent Louis Abderrahman El Bakali Duy Quang Dao 《RSC advances》2022,12(3):1499
Direct and indirect antioxidant activities of rosmarinic acid (RA) based on HOO˙/CH3OO˙ radical scavenging and Fe(iii)/Fe(ii) ion chelation were theoretically studied using density functional theory at the M05-2X/6-311++G(2df,2p) level of theory. First, four antioxidant mechanisms including hydrogen atom transfer (HAT), radical adduct formation (RAF), proton loss (PL) and single electron transfer (SET) were investigated in water and pentyl ethanoate (PEA) phases. Regarding the free radical scavenging mechanism, HAT plays a decisive role with overall rate coefficients of 1.84 × 103 M−1 s−1 (HOO˙) and 4.49 × 103 M−1 s−1 (CH3OO˙) in water. In contrast to PL, RAF and especially SET processes, the HAT reaction in PEA is slightly more favorable than that in water. Second, the [Fe(iii)(H2O)6]3+ and [Fe(ii)(H2O)6]2+ ion chelating processes in an aqueous phase are both favorable and spontaneous especially at the O5, site-1, and site-2 positions with large negative ΔrG0 values and great formation constant Kf. Finally, the pro-oxidant risk of RA− was also considered via the Fe(iii)-to-Fe(ii) complex reduction process, which may initiate Fenton-like reactions forming reactive HO˙ radicals. As a result, RA− does not enhance the reduction process when ascorbate anions are present as reducing agents, whereas the pro-oxidant risk becomes remarkable when superoxide anions are found. The results encourage further attempts to verify the speculation using more powerful research implementations of the antioxidant activities of rosmarinic acid in relationship with its possible pro-oxidant risks.Direct and indirect antioxidant activities of rosmarinic acid (RA) based on HOO˙/CH3OO˙ radical scavenging and Fe(iii)/Fe(ii) ion chelation were theoretically studied using density functional theory at the M05-2X/6-311++G(2df,2p) level of theory. 相似文献
79.
D. Greg Farwell Quang C. Luu Paul J. Donald Deborah Amott Anh Q. Truong Regina F. Gandour‐Edwards N. Nitin 《International journal of cancer. Journal international du cancer》2013,132(7):1613-1623
Noninvasive localized measurement of extracellular pH in cancer tissues can have a significant impact on the management of cancer. Despite its significance, there are limited approaches for rapid and noninvasive measurement of local pH in a clinical environment. In this study, we demonstrate the potential of noninvasive topical delivery of Alexa‐647 labeled pHLIP (pH responsive peptide conjugated with Alexa Fluor® 647) to image changes in extracellular pH associated with head and neck squamous cell carcinoma using widefield and high resolution imaging. We report a series of preclinical analyses to evaluate the optical contrast achieved after topical delivery of Alexa‐647 labeled pHLIP in intact fresh human tissue specimens using widefield and high‐resolution fluorescence imaging. Using topical delivery, Alexa‐647 labeled pHLIP can be rapidly delivered throughout the epithelium of intact tissues with a depth exceeding 700 µm. Following labeling with Alexa‐647 labeled pHLIP, the mean fluorescent contrast increased four to eight fold higher in clinically abnormal tissues as compared to paired clinically normal biopsies. Furthermore, the imaging approach showed significant differences in fluorescence contrast between the cancer and the normal biopsies across diverse patients and different anatomical sites (unpaired comparison). The fluorescence contrast differences between clinically abnormal and normal tissues were in agreement with the pathologic evaluation. Topical application of fluorescently labeled pHLIP can detect and differentiate normal from cancerous tissues using both widefield and high resolution imaging. This technology will provide an effective tool to assess tumor margins during surgery and improve detection and prognosis of head and neck cancer. 相似文献
80.