全文获取类型
收费全文 | 3939篇 |
免费 | 260篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 59篇 |
妇产科学 | 48篇 |
基础医学 | 495篇 |
口腔科学 | 52篇 |
临床医学 | 459篇 |
内科学 | 851篇 |
皮肤病学 | 30篇 |
神经病学 | 260篇 |
特种医学 | 152篇 |
外科学 | 694篇 |
综合类 | 48篇 |
一般理论 | 4篇 |
预防医学 | 316篇 |
眼科学 | 89篇 |
药学 | 291篇 |
中国医学 | 1篇 |
肿瘤学 | 341篇 |
出版年
2024年 | 8篇 |
2023年 | 49篇 |
2022年 | 75篇 |
2021年 | 167篇 |
2020年 | 65篇 |
2019年 | 137篇 |
2018年 | 152篇 |
2017年 | 100篇 |
2016年 | 103篇 |
2015年 | 118篇 |
2014年 | 200篇 |
2013年 | 224篇 |
2012年 | 350篇 |
2011年 | 363篇 |
2010年 | 216篇 |
2009年 | 155篇 |
2008年 | 258篇 |
2007年 | 279篇 |
2006年 | 226篇 |
2005年 | 238篇 |
2004年 | 204篇 |
2003年 | 208篇 |
2002年 | 174篇 |
2001年 | 21篇 |
2000年 | 18篇 |
1999年 | 12篇 |
1998年 | 28篇 |
1997年 | 16篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1991年 | 1篇 |
1984年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1949年 | 2篇 |
1936年 | 2篇 |
1934年 | 2篇 |
1930年 | 2篇 |
排序方式: 共有4209条查询结果,搜索用时 15 毫秒
71.
Kathleen J. Yost Darren A. DeWalt Lee A. Lindquist Elizabeth A. Hahn 《Patient education and counseling》2013
Objectives
To confirm the association of health literacy scores as measured by Health Literacy Assessment Using Talking Touchscreen Technology (Health LiTT) with cognitive ability and education. To determine whether this association differs by cognitive task.Methods
Cognitive impairment was measured using the Mini-Cog, which combines a delayed word recall task (WRT) and a clock drawing task (CDT) to yield an overall classification of normal versus cognitively impaired. Participants were recruited from primary care clinics that provide care to underserved patients.Results
Participants (n = 574) were predominantly non-Hispanic black (67%) with a mean age of 46 years, 50% did not have health insurance, 56% had a high school education or less and 21% screened positive for cognitive impairment. Overall cognitive ability and education were significantly associated with health literacy after adjusting for other variables, including race/ethnicity and physical health. We observed a stronger association between the CDT and health literacy than between the WRT and health literacy.Conclusion
By confirming hypothesized associations, this study provides additional support of the validity of Health LiTT.Practice implications
Health LiTT is a reliable and valid tool that researchers and clinicians can use to identify individuals who might have difficulty understanding health information. 相似文献72.
Darren M. Winograd Cara L. Fresquez Madison Egli Emily K. Peterson Alyssa R. Lombardi Allison Megale Yajaira A. Cabrera Tineo Michael G. Verile Alison L. Phillips Jessica Y. Breland Susan Santos Lisa M. McAndrew 《Patient education and counseling》2021,104(8):1834-1859
ObjectiveIn response to COVID-19, we conducted a rapid review of risk communication interventions to mitigate risk from viruses to determine if such interventions are efficacious.MethodsWe searched for risk communication interventions in four databases: Medline, PsycInfo, the ProQuest Coronavirus Research Database, and CENTRAL. The search produced 1572 articles. Thirty-one articles were included in the final review.ResultsResults showed risk communication interventions can produce cognitive and behavior changes around viruses. Results were more consistently positive for interventions focused on HIV/AIDS as compared to influenza. There was no consistent best intervention approach when comparing peer health, audio/visual, and intensive multi-media interventions. Tailoring risk communication toward a target population, in comparison to not tailoring, was related to better outcomes.ConclusionThe results suggest that risk communication interventions can be efficacious at reducing risk from viruses. They also highlight the complexity of risk communication interventions. Additional research is needed to understand the mechanisms that lead risk communication to reduce risk from viruses.Practical valueResults support risk communication interventions to reduce risk from viruses. 相似文献
73.
Darren Conlon Toby Raeburn Timothy Wand 《Collegian (Royal College of Nursing, Australia)》2021,28(3):261-267
BackgroundNurses working in mental health routinely face difficult decisions regarding confidentiality and disclosure of patient information. There is public interest in protecting patient confidentiality, and there is a competing public interest in disclosing relevant confidential information to protect the patient or others from harm. However, inappropriate disclosures may constitute a breach of confidentiality. Despite the gravity of this situation, there is a paucity of literature to guide nurses’ decision-making processes regarding confidentiality and disclosure.AimTo examine decision-making processes of a nurse working in mental health, regarding disclosure of personal health information of a patient assessed as posing a risk.MethodsQualitative interpretivist approach using thematic analysis of data derived from an instrumental case study of NK v Northern Sydney Central Coast Area Health Service 2010, a Civil and Administrative Tribunal matter in New South Wales, Australia.FindingsThree important legal concerns relevant to nurses’ decision-making processes are illuminated. Firstly, for risk assessment there was an emphasis on a static notion of dangerousness. Secondly, rules of confidentiality and disclosure were not adequately observed. Thirdly, confidential information was disclosed without valid justification.DiscussionInappropriate decision-making processes that may lead to a breach of patient confidentiality were evident in the findings. Gaps in understanding nurses’ decision-making processes pertaining to confidentiality and disclosure of patient information that may be addressed by future research were also revealed.ConclusionFuture research that addresses gaps in understanding nurses’ decision-making processes identified by this instrumental case study would provide greater guidance for nurses when making decisions regarding confidentiality and disclosure related to risk. 相似文献
74.
75.
76.
Multiple origins of crassulacean acid metabolism and the epiphytic habit in the Neotropical family Bromeliaceae
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Crayn DM Winter K Smith JA 《Proceedings of the National Academy of Sciences of the United States of America》2004,101(10):3703-3708
The large Neotropical family Bromeliaceae presents an outstanding example of adaptive radiation in plants, containing a wide range of terrestrial and epiphytic life-forms occupying many distinct habitats. Diversification in bromeliads has been linked to several key innovations, including water- and nutrient-impounding phytotelmata, absorptive epidermal trichomes, and the water-conserving mode of photosynthesis known as crassulacean acid metabolism (CAM). To clarify the origins of CAM and the epiphytic habit, we conducted a phylogenetic analysis of nucleotide sequences for 51 bromeliad taxa by using the plastid loci matK and the rps16 intron, combined with a survey of photosynthetic pathway determined by carbon-isotope ratios for 1,873 species representing 65% of the family. Optimization of character-states onto the strict consensus tree indicated that the last common ancestor of Bromeliaceae was a terrestrial C(3) mesophyte, probably adapted to moist, exposed, nutrient-poor habitats. Both CAM photosynthesis and the epiphytic habit evolved a minimum of three times in the family, most likely in response to geological and climatic changes in the late Tertiary. The great majority of epiphytic forms are now found in two lineages: in subfamily Tillandsioideae, in which C(3) photosynthesis was the ancestral state and CAM developed later in the most extreme epiphytes, and in subfamily Bromelioideae, in which CAM photosynthesis predated the appearance of epiphytism. Subsequent radiation of the bromelioid line into less xeric habitats has led to reversion to C(3) photosynthesis in some taxa, showing that both gain and loss of CAM have occurred in the complex evolutionary history of this family. 相似文献
77.
Transcatheter Valve Repair for Patients With Mitral Regurgitation: 30-Day Results of the CLASP Study
D. Scott Lim Saibal Kar Konstantinos Spargias Robert M. Kipperman William W. O’Neill Martin K.C. Ng Neil P. Fam Darren L. Walters John G. Webb Robert L. Smith Michael J. Rinaldi Azeem Latib Gideon N. Cohen Ulrich Schäfer Leo Marcoff Prashanthi Vandrangi Patrick Verta Ted E. Feldman 《JACC: Cardiovascular Interventions》2019,12(14):1369-1378
ObjectivesThe authors report the procedural and 30-day results of the PASCAL Transcatheter Valve Repair System (Edwards Lifesciences, Irvine, California) in patients with mitral regurgitation (MR) enrolled in the multicenter, prospective, single-arm CLASP study.BackgroundSevere MR may lead to symptoms, impaired quality of life, and reduced functional capacity when untreated.MethodsEligible patients had grade 3+ or 4+ MR despite optimal medical therapy and were deemed appropriate for the study by the local heart team. All outcomes were assessed through 30 days post-procedure. Major adverse events (MAEs) were adjudicated by an independent clinical events committee, and echocardiographic images were assessed by a core laboratory. The primary safety endpoint was the rate of MAEs at 30 days.ResultsBetween June 2017 and September 2018, 62 patients with grade 3+ or 4+ MR were enrolled. The mean age was 76.5 years, and 51.6% of patients were in New York Heart Association functional class III or IV, with 56% functional, 36% degenerative, and 8% mixed MR etiology. At 30 days, the MAE rate was 6.5%, with an all-cause mortality rate of 1.6% and no occurrence of stroke; 98% had MR grade ≤2+, with 86% with MR grade ≤1+ (p < 0.0001); and 85% were in New York Heart Association functional class I or II (p < 0.0001). Six-minute walk distance improved by 36 m (p = 0.0018), and Kansas City Cardiomyopathy Questionnaire and EQ-5D scores improved by 17 (p < 0.0001) and 10 (p = 0.0004) points, respectively.ConclusionsThe PASCAL repair system showed feasibility and acceptable safety in the treatment of patients with grade 3+ or 4+ MR. MR severity, irrespective of etiology, was significantly reduced and accompanied by clinically and statistically significant improvements in functional status, exercise capacity, and quality of life. (The CLASP Study Edwards PASCAL Transcatheter Mitral Valve Repair System Study; NCT03170349) 相似文献
78.
Gallavotti A Barazesh S Malcomber S Hall D Jackson D Schmidt RJ McSteen P 《Proceedings of the National Academy of Sciences of the United States of America》2008,105(39):15196-15201
The plant growth hormone auxin plays a critical role in the initiation of lateral organs and meristems. Here, we identify and characterize a mutant, sparse inflorescence1 (spi1), which has defects in the initiation of axillary meristems and lateral organs during vegetative and inflorescence development in maize. Positional cloning shows that spi1 encodes a flavin monooxygenase similar to the YUCCA (YUC) genes of Arabidopsis, which are involved in local auxin biosynthesis in various plant tissues. In Arabidopsis, loss of function of single members of the YUC family has no obvious effect, but in maize the mutation of a single yuc locus causes severe developmental defects. Phylogenetic analysis of the different members of the YUC family in moss, monocot, and eudicot species shows that there have been independent expansions of the family in monocots and eudicots. spi1 belongs to a monocot-specific clade, within which the role of individual YUC genes has diversified. These observations, together with expression and functional data, suggest that spi1 has evolved a dominant role in auxin biosynthesis that is essential for normal maize inflorescence development. Analysis of the interaction between spi1 and genes regulating auxin transport indicate that auxin transport and biosynthesis function synergistically to regulate the formation of axillary meristems and lateral organs in maize. 相似文献
79.
Hideyuki Kawashima Patrick W. Serruys Rodrigo Modolo Michele Pighi Rutao Wang Masafumi Ono Jean-Paul Aben Chun Chin Chang Hadewych Van Hauwermeiren Bill Brunnett Martijn Cox Liesbeth Rosseel Darren Mylotte Philippe Pibarot Willem J. Flameng Yoshinobu Onuma Osama Soliman 《JACC: Cardiovascular Interventions》2021,14(14):1523-1534
ObjectivesThis study aimed to validate a dedicated software for quantitative videodensitometric angiographic assessment of mitral regurgitation (QMR).BackgroundQuantitative videodensitometric aortography of aortic regurgitation using the time-density principle is a well-documented technique, but the angiographic assessment of mitral regurgitation (MR) remains at best semi-quantitative and operator dependent.MethodsFourteen sheep underwent surgical mitral valve replacement using 2 different prostheses. Pre-sacrifice left ventriculograms were used to assess MR fraction (MRF) using QMR and MR volume (MRV). In an independent core lab, the CAAS QMR 0.1 was used for QMR analysis. In vitro MRF and MRV were assessed in a mock circulation at a comparable cardiac output to the in vivo one by thermodilution. The correlations and agreements of in vitro and in vivo MRF, MRV, and interobserver reproducibility for QMR analysis were assessed using the averaged cardiac cycles (CCs).ResultsIn vivo derived MRF by QMR strongly correlated with in vitro derived MRF, regardless of the number of the CCs analyzed (best correlation: 3 CCs y = 0.446 + 0.994x; R = 0.784; p =0.002). The mean absolute difference between in vitro derived MRF and in vivo derived MRF from 3 CCs was 0.01 ± 4.2% on Bland-Altman analysis. In vitro MRV and in vivo MRV from 3 CCs were very strongly correlated (y = 0.196 + 1.255x; R = 0.839; p < 0.001). The mean absolute difference between in vitro MRV and in vivo MRV from 3 CCs was –1.4 ± 1.9 ml. There were very strong correlations of in vivo MRF between 2 independent analysts, regardless of the number of the CCs.ConclusionsIn vivo MRF using the novel software is feasible, accurate, and highly reproducible. These promising results have led us to initiate the first human feasibility study comprising patients undergoing percutaneous mitral valve edge-to-edge repair. 相似文献
80.
Hitomi Hosoya Andrey S. Dobroff Wouter H. P. Driessen Vittorio Cristini Lina M. Brinker Fernanda I. Staquicini Marina Cardó-Vila Sara D’Angelo Fortunato Ferrara Bettina Proneth Yu-Shen Lin Darren R. Dunphy Prashant Dogra Marites P. Melancon R. Jason Stafford Kohei Miyazono Juri G. Gelovani Kazunori Kataoka C. Jeffrey Brinker Richard L. Sidman Wadih Arap Renata Pasqualini 《Proceedings of the National Academy of Sciences of the United States of America》2016,113(7):1877-1882
A major challenge of targeted molecular imaging and drug delivery in cancer is establishing a functional combination of ligand-directed cargo with a triggered release system. Here we develop a hydrogel-based nanotechnology platform that integrates tumor targeting, photon-to-heat conversion, and triggered drug delivery within a single nanostructure to enable multimodal imaging and controlled release of therapeutic cargo. In proof-of-concept experiments, we show a broad range of ligand peptide-based applications with phage particles, heat-sensitive liposomes, or mesoporous silica nanoparticles that self-assemble into a hydrogel for tumor-targeted drug delivery. Because nanoparticles pack densely within the nanocarrier, their surface plasmon resonance shifts to near-infrared, thereby enabling a laser-mediated photothermal mechanism of cargo release. We demonstrate both noninvasive imaging and targeted drug delivery in preclinical mouse models of breast and prostate cancer. Finally, we applied mathematical modeling to predict and confirm tumor targeting and drug delivery. These results are meaningful steps toward the design and initial translation of an enabling nanotechnology platform with potential for broad clinical applications.A long-term goal in contemporary cancer nanomedicine has been to design and generate drug delivery systems that improve the narrow therapeutic window associated with conventional chemotherapeutics (1, 2). Conceptually, several nanotechnology-based entity candidates, including protocells (3), biosynthetic nanoparticles (NPs), viruses, and liposome-based nanoparticles, could be targeted for active delivery through a defined cell surface ligand receptor system and/or physically triggered for finely tuned cargo release (2, 4, 5).Numerous efforts have been made to functionalize NPs by combining them with antibodies, aptamers, peptides, vitamins, or carbohydrates (6–8), but the majority of studies involve untargeted nanoplatforms (4, 9). In practice, targeting NPs is far from trivial, and ongoing challenges include synthesis and purification, selection of an appropriate ligand receptor, and specific composition for NP conjugation. Even the conjugation reaction itself may alter the binding of the tumor-targeting moiety to its receptor through conformational changes, steric freedom restriction, or orientation distortion (10, 11). Unfortunately, the cost-to-benefit ratio of these modifications often elevate the complexity of the NP synthesis, complicating regulatory hurdles because of formulations that are heterogeneous or difficult to reproduce (10, 12, 13).To minimize such drawbacks, NPs can be functionalized via virus-based nanoplatforms as an alternative for targeted cargo delivery (14–16). In particular, filamentous bacteriophage (phage)—a prokaryotic virus—is an attractive candidate to develop a bionanomedicine for cancer therapeutics because phage particles are cost-effectively produced with biological uniformity, as well as being physically robust and stable under harsh conditions (17). Notably, phage-based nanoplatforms are biocompatible and nonpathogenic with eukaryotic organisms and are able to preserve the desired cell targeting and internalization (18). Moreover, phage particles are ideal for incorporating other NPs, which can be released after reaching the tumor site. An admixture of colloidal gold NP (AuNP) with phage particles spontaneously organizes into hydrogel network-like fractal structures (19, 20). These hydrogel networks offer convenient multifunctional integration within a single entity for tumor targeting, enhanced fluorescence and dark-field microscopy, near-infrared (NIR) photon-to-heat conversion, and surface-enhanced Raman scattering (SERS)-based detection (20, 21).In the present work, we developed a tumor targeting theranostic (meaning a combination of therapeutics and diagnostics) hydrogel-based nanoplatform that enables ligand-directed tumor targeting, multimodal imaging capability, and triggered therapeutic cargo release. Our data suggest that targeted hydrogel photothermal therapy represents a functional theranostic approach (fostering “see and treat, treat and see”) in the diagnosis and management of tumors. 相似文献