全文获取类型
收费全文 | 4287篇 |
免费 | 242篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 51篇 |
儿科学 | 167篇 |
妇产科学 | 54篇 |
基础医学 | 456篇 |
口腔科学 | 174篇 |
临床医学 | 341篇 |
内科学 | 1089篇 |
皮肤病学 | 55篇 |
神经病学 | 577篇 |
特种医学 | 166篇 |
外科学 | 616篇 |
综合类 | 7篇 |
预防医学 | 138篇 |
眼科学 | 65篇 |
药学 | 274篇 |
中国医学 | 10篇 |
肿瘤学 | 316篇 |
出版年
2023年 | 32篇 |
2022年 | 76篇 |
2021年 | 153篇 |
2020年 | 82篇 |
2019年 | 96篇 |
2018年 | 130篇 |
2017年 | 99篇 |
2016年 | 121篇 |
2015年 | 129篇 |
2014年 | 162篇 |
2013年 | 246篇 |
2012年 | 360篇 |
2011年 | 340篇 |
2010年 | 175篇 |
2009年 | 173篇 |
2008年 | 238篇 |
2007年 | 288篇 |
2006年 | 243篇 |
2005年 | 233篇 |
2004年 | 228篇 |
2003年 | 183篇 |
2002年 | 184篇 |
2001年 | 45篇 |
2000年 | 24篇 |
1999年 | 46篇 |
1998年 | 39篇 |
1997年 | 44篇 |
1996年 | 24篇 |
1995年 | 28篇 |
1994年 | 20篇 |
1993年 | 27篇 |
1992年 | 28篇 |
1991年 | 28篇 |
1990年 | 19篇 |
1989年 | 29篇 |
1988年 | 13篇 |
1987年 | 15篇 |
1986年 | 19篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 16篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1975年 | 5篇 |
1973年 | 9篇 |
1961年 | 3篇 |
1931年 | 4篇 |
排序方式: 共有4556条查询结果,搜索用时 15 毫秒
101.
102.
Gian-Battista Chierchia Giacomo Di Giovanni Juan Sieira-Moret Carlo de Asmundis Giulio Conte Moises Rodriguez-Mañero Ruben Casado-Arroyo Giannis Baltogiannis Gaetano Paparella Giuseppe Ciconte Andrea Sarkozy Pedro Brugada 《Journal of interventional cardiac electrophysiology》2014,39(2):145-151
Background
The second-generation cryoballoon (CB-A) (Arctic Front Advance, Cryocath, Medtronic, MN, USA) might significantly improve procedural outcome with respect to the first-generation balloon. These technological improvements might also question the current recommendation of the need a 4-min freeze to achieve durable pulmonary vein isolation (PVI).Objective
The main aim of the study was to analyze the procedural efficacy of a 3-min freeze–thaw cycles with the CB-A balloon in the terms of rates of acute PVI and 6-month outcome.Methods
Patients having undergone CB-A for PAF or early persistent AF, with 3-min freeze–thaw cycles were consecutively included in our analysis. Acute procedural success was measured in terms of the rate of PVI. Short-term follow-up was evaluated by the means of 24-h Holters and clinical examinations at regular intervals.Results
Fifty-two consecutive patients (35 male (67 %); mean age, 59.8?±?10.5) were included. Mean procedure and fluoroscopy times were 96?±?15 and 13.2?±?8.3 min, respectively. Mean time from groin puncture to catheter extraction was 60.4?±?20 min. After a mean of 1.5 freeze cycles per vein of 3 min in duration, all 208 (100 %) PVs could be isolated with the CB-A. A total 192 (91 %) veins were isolated during the first freeze. At a mean of 5.7-month follow-up, 82 % of patients were free of AF.Conclusion
CB-A is effective in producing PVI by using 3-min-duration freeze cycles. After a mean of 1.5 freeze per vein, freedom from AF was achieved in 82 % of patients at 6-month follow-up. 相似文献103.
Hypothalamitis: a diagnostic and therapeutic challenge 总被引:1,自引:0,他引:1
Antonio?BianchiEmail author Marilda?Mormando Francesco?Doglietto Linda?Tartaglione Serena?Piacentini Libero?Lauriola Giulio?Maira Laura?De Marinis 《Pituitary》2014,17(3):197-202
To report an unusual case of biopsy-proven autoimmune hypophysitis with predominant hypothalamic involvement associated with empty sella, panhypopituitarism, visual disturbances and antipituitary antibodies positivity. We present the history, physical findings, hormonal assay results, imaging, surgical findings and pathology at presentation, together with a 2-year follow-up. A literature review on the hypothalamic involvement of autoimmune hypophysitis with empty sella was performed. A 48-year-old woman presented with polyuria, polydipsia, asthenia, diarrhea and vomiting. The magnetic resonance imaging (MRI) revealed a clear suprasellar (hypothalamic) mass, while the pituitary gland appeared atrophic. Hormonal testing showed panhypopituitarism and hyperprolactinemia; visual field examination was normal. Pituitary serum antibodies were positive. Two months later an MRI documented a mild increase of the lesion. The patient underwent biopsy of the lesion via a transsphenoidal approach. Histological diagnosis was lymphocytic “hypothalamitis”. Despite 6 months of corticosteroid therapy, the patient developed bitemporal hemianopia and blurred vision, without radiological evidence of chiasm compression, suggesting autoimmune optic neuritis with uveitis. Immunosuppressive treatment with azathioprine was then instituted. Two months later, an MRI documented a striking reduction of the hypothalamic lesion and visual field examination showed a significant improvement. The lesion is stable at the 2-year follow-up. For the first time we demonstrated that “hypothalamitis” might be the possible evolution of an autoimmune hypophysitis, resulting in pituitary atrophy, secondary empty sella and panhypopituitarism. Although steroid treatment is advisable as a first line therapy, immunosuppressive therapy with azathioprine might be necessary to achieve disease control. 相似文献
104.
Giuseppe Stabile Antoine Lepillier Ermenegildo De Ruvo Marco Scaglione Matteo Anselmino Frederic Sebag Domenico Pecora Mark Gallagher Mariano Rillo Graziana Viola Luca Rossi Valerio De Santis Maurizio Landolina Antonello Castro Massimo Grimaldi Nicolas Badenco Maurizio Del Greco Antonio De Simone Ennio Pisan Salim Abbey Filippo Lamberti Antonio Pani Giulio Zucchelli Giuseppe Sgarito Daniela Dugo Emanuele Bertaglia Teresa Strisciuglio Francesco Solimene 《Journal of cardiovascular electrophysiology》2020,31(7):1694-1701
105.
Bonomo Giulio Bertani Giulio A. Carrabba Giorgio G. Ferrante Emanuele Pluderi Mauro Guastella Claudio Pignataro Lorenzo Rampini Paolo Mantovani Giovanna Locatelli Marco 《Pituitary》2020,23(5):552-557
Pituitary - The aim of the present study is to assess the predictive value of the suprasellar volume (SSV) of nonfunctioning pituitary adenomas (NFPAs) for visual field (VF) impairment in order to... 相似文献
106.
Mechanism of luminal patency of the self‐expanding sideguard sidebranch stent: Evaluation by intravascular ultrasound and optical coherence tomography
下载免费PDF全文
![点击此处可从《Catheterization and cardiovascular interventions》网站下载免费的PDF全文](/ch/ext_images/free.gif)
107.
108.
Paolo Limongelli Chiara Vitiello Andrea Belli Madhava Pai Salvatore Tolone Gianmattia del Genio Luigi Brusciano Giovanni Docimo Nagy Habib Giulio Belli Long Richard Jiao Ludovico Docimo 《World journal of gastroenterology : WJG》2014,20(46):17595-17602
AIM: To study costs of laparoscopic and open liver and pancreatic resections, all the compiled data from available observational studies were systematically reviewed.METHODS: A systematic review of the literature was performed using the Medline, Embase, PubMed, and Cochrane databases to identify all studies published up to 2013 that compared laparoscopic and open liver [laparoscopic hepatic resection (LLR) vs open liver resection (OLR)] and pancreatic [laparoscopic pancreatic resection (LPR) vs open pancreatic resection] resection. The last search was conducted on October 30, 2013.RESULTS: Four studies reported that LLR was associated with lower ward stay cost than OLR (2972 USD vs 5291 USD). The costs related to equipment (3345 USD vs 2207 USD) and theatre (14538 vs 11406) were reported higher for LLR. The total cost was lower in patients managed by LLR (19269 USD) compared to OLR (23419 USD). Four studies reported that LPR was associated with lower ward stay cost than OLR (6755 vs 9826 USD). The costs related to equipment (2496 USD vs 1630 USD) and theatre (5563 vs 4444) were reported higher for LPR. The total cost was lower in the LPR (8825 USD) compared to OLR (13380 USD).CONCLUSION: This systematic review support the economic advantage of laparoscopic over open approach to liver and pancreatic resection. 相似文献
109.
Matteo Ballottari Marcelo J. P. Alcocer Cosimo D’Andrea Daniele Viola Tae Kyu Ahn Annamaria Petrozza Dario Polli Graham R. Fleming Giulio Cerullo Roberto Bassi 《Proceedings of the National Academy of Sciences of the United States of America》2014,111(23):E2431-E2438
In oxygenic photosynthetic eukaryotes, the hydroxylated carotenoid zeaxanthin is produced from preexisting violaxanthin upon exposure to excess light conditions. Zeaxanthin binding to components of the photosystem II (PSII) antenna system has been investigated thoroughly and shown to help in the dissipation of excess chlorophyll-excited states and scavenging of oxygen radicals. However, the functional consequences of the accumulation of the light-harvesting complex I (LHCI) proteins in the photosystem I (PSI) antenna have remained unclarified so far. In this work we investigated the effect of zeaxanthin binding on photoprotection of PSI–LHCI by comparing preparations isolated from wild-type Arabidopsis thaliana (i.e., with violaxanthin) and those isolated from the A. thaliana nonphotochemical quenching 2 mutant, in which violaxanthin is replaced by zeaxanthin. Time-resolved fluorescence measurements showed that zeaxanthin binding leads to a previously unrecognized quenching effect on PSI–LHCI fluorescence. The efficiency of energy transfer from the LHCI moiety of the complex to the PSI reaction center was down-regulated, and an enhanced PSI resistance to photoinhibition was observed both in vitro and in vivo. Thus, zeaxanthin was shown to be effective in inducing dissipative states in PSI, similar to its well-known effect on PSII. We propose that, upon acclimation to high light, PSI–LHCI changes its light-harvesting efficiency by a zeaxanthin-dependent quenching of the absorbed excitation energy, whereas in PSII the stoichiometry of LHC antenna proteins per reaction center is reduced directly.In eukaryotic photosynthetic organisms, photosystem I (PSI) and photosystem II (PSII) comprise a core complex hosting cofactors involved in electron transport and an outer antenna system made of light-harvesting complexes (LHCs): Lhcas for PSI and Lhcbs for PSII. The core complexes bind chlorophyll a (Chl a) and β-carotene, whereas the outer antenna system, in addition to Chl a, binds chlorophyll b (Chl b) and xanthophylls. Despite their overall similarity, PSI and PSII differ in the rate at which they trap excitation energy at the reaction center (RC), with PSI being faster than PSII (1–9). They also differ in their structure (10–12). PSI is monomeric and carries its antenna moiety on only one side as a half-moon–shaped structure whose size is not modulated by growth conditions (13, 14). PSII, on the other hand, is found mainly as a dimeric core surrounded by an inner layer of antenna proteins (Lhcb4–6) and an outer layer of heterotrimeric LHCII complexes (Lhcb 1–3) whose stoichiometry varies depending on the growth conditions (7, 12, 13, 15). Acclimation to high irradiance leads to a lower number of trimers per PSII RC accompanied by loss of the monomeric Lhcb6. These slow acclimative responses regulate the excitation pressure on the PSII RC, preventing saturation of the electron transport chain (16) and the oxidative stress in high light (HL), leading to photoinhibition. The response to rapid changes in light level is managed by turning on some photoprotective mechanisms, such as the nonphotochemical quenching (NPQ) of the excess energy absorbed by PSII (16), which is activated by the acidification of the thylakoid lumen and protonation of the trigger protein PsbS or LhcSR. Low luminal pH also activates violaxanthin de-epoxidase (VDE), catalyzing the de-epoxidation of the xanthophyll violaxanthin to zeaxanthin (17, 18), a scavenger of reactive oxygen species (ROS) produced by excess light (9, 13). Zeaxanthin also enhances NPQ, as observed in vivo by a decrease of PSII fluorescence (19). The short-term effects of exposure to HL on PSI have been disregarded thus far. Because of its rapid photochemistry, PSI shows low fluorescence emission, implying a low 1Chl* concentration and a low probability that chlorophyll triplet states will be formed by intersystem crossing. This characteristic suggests that the formation of oxygen singlet excited states (1O*2) is reduced and that NPQ phenomena in photoprotection are less relevant in PSI (20, 21). Nevertheless, several reports have shown that, especially in the cold (22–29), PSI can exhibit photo-inhibition, with its Lhca proteins being the primary target (24, 30). Upon synthesis in HL, zeaxanthin binding could be traced to two different types of binding site. One, designated “V1,” is located in the periphery of LHCII trimers (31–33). The second, designated “L2,” has an inner location in the dimeric Lhca1–4 and the monomeric Lhcb4–6 members of the LHC family (34–37). Experimental determination of the efficiency of the violaxanthin-to-zeaxanthin exchange yielded a maximal score in the Lhca3 and Lhca4 subunits (24, 25). Interestingly, Lhca1/4 and Lhca2/3 are bound to the PSI core as dimers that can be isolated in fractions identified as “LHCI-730” and “LHCI-680,” respectively, both accumulating zeaxanthin to a de-epoxidation index of ∼0.2 (20, 38). Lhca3 and Lhca4 carry low-absorption-energy chlorophyll forms known as “red forms” (39, 40) that are responsible for the red-shifted PSI emission peak at 730–740 nm at 77 K. The molecular basis for red forms is an excitonic interaction of two chromophores: chlorophylls 603 and 609 located a few angstroms from the xanthophyll in site L2, which can be either violaxanthin or zeaxanthin depending on light conditions (41, 42). It is unclear whether the binding of zeaxanthin to the PSI–LHCI complex has specific physiological function(s) or is simply a result of its common origin with Lhcb proteins.The goal of this study was to understand whether zeaxanthin plays a role in PSI–LHCI photoprotection. To investigate the role of zeaxanthin bound to Lhca proteins, we analyzed the changes in antenna size and Chl a fluorescence dynamics in PSI supercomplexes binding either violaxanthin or zeaxanthin. We found a zeaxanthin-dependent regulation of PSI antenna size and an enhanced resistance to excess light upon zeaxanthin binding. These results show that dynamic changes in the efficiency of light use and in photoprotection capacity are not exclusive to PSII, as previously thought; instead, eukaryotic photosynthetic organisms modulate the function of both photosystems in a coordinated manner. 相似文献
110.