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排序方式: 共有687条查询结果,搜索用时 31 毫秒
1.
《Journal of the American Dental Association (1939)》2022,153(3):208-220
BackgroundAerosols are generated routinely during patient care in dentistry. Managing exposure risk requires understanding characteristics of aerosols created during procedures such as those performed using high-speed drills that operate at 200,000 revolutions per minute.MethodsA trained dentist performed drilling procedures on a manikin’s incisors (teeth nos. 8 and 9) using a high-speed drill and high-volume evacuator. The authors used high-speed imaging to visualize the formation and transport of aerosol clouds and particle sampling to measure aerosol concentration and size distribution at several locations. The authors studied several aerosol mitigation strategies.ResultsAerosols produced during high-speed drilling were erratic and yielded high concentrations that were at least an order of magnitude above baseline. High-speed imaging showed aerosols initially travelled at 1 m per second. Owing to erratic behavior of aerosols, supplemental suction was not effective at collecting all aerosols; however, barriers were effective.ConclusionsBarriers are the most effective mitigation strategy. Other methods studied have limitations and risks. To the authors’ knowledge, this article presents the first characterization of aerosols generated during high-speed drilling by a dentist.Practical ImplicationsWith thorough preoperative planning and the use of this investigation’s findings about effectiveness of mitigation strategies as a guide, dental offices may be able to return to prepandemic productivity. 相似文献
2.
《Radiography》2019,25(4):e119-e122
Aliasing artefact is an imaging distortion phenomenon experienced in a wide variety of medical imaging modalities. This case report illustrates its occurrence during planar gamma camera nuclear medicine imaging under non-clinical conditions using experimental incorrect selection of collimators. In accordance with provision of an optimal service, nuclear medicine practitioners are recommended to have sufficient technical expertise along with knowledge of gamma camera operation. The purpose, construction and interaction of collimators used during planar imaging are presented herein with specific regards to the aliasing phenomenon. Furthermore, this case report recommends the careful planning of worklists to avoid frequent collimator changes to reduce the risk of human error. 相似文献
3.
《JACC: Cardiovascular Imaging》2021,14(9):1819-1828
ObjectivesThis study sought to describe worldwide variations in the use of myocardial perfusion imaging hardware, software, and imaging protocols and their impact on radiation effective dose (ED).BackgroundConcerns about long-term effects of ionizing radiation have prompted efforts to identify strategies for dose optimization in myocardial perfusion scintigraphy. Studies have increasingly shown opportunities for dose reduction using newer technologies and optimized protocols.MethodsData were submitted voluntarily to the INCAPS (International Atomic Energy Agency Nuclear Cardiology Protocols Study) registry, a multinational, cross-sectional study comprising 7,911 imaging studies from 308 labs in 65 countries. The study compared regional use of camera technologies, advanced post-processing software, and protocol characteristics and analyzed the influence of each factor on ED.ResultsCadmium-zinc-telluride and positron emission tomography (PET) cameras were used in 10% (regional range 0% to 26%) and 6% (regional range 0% to 17%) of studies worldwide. Attenuation correction was used in 26% of cases (range 10% to 57%), and advanced post-processing software was used in 38% of cases (range 26% to 64%). Stress-first single-photon emission computed tomography (SPECT) imaging comprised nearly 20% of cases from all world regions, except North America, where it was used in just 7% of cases. Factors associated with lower ED and odds ratio for achieving radiation dose ≤9 mSv included use of cadmium-zinc-telluride, PET, advanced post-processing software, and stress- or rest-only imaging. Overall, 39% of all studies (97% PET and 35% SPECT) were ≤9 mSv, while just 6% of all studies (32% PET and 4% SPECT) achieved a dose ≤3 mSv.ConclusionsNewer-technology cameras, advanced software, and stress-only protocols were associated with reduced ED, but worldwide adoption of these practices was generally low and varied significantly between regions. The implementation of dose-optimizing technologies and protocols offers an opportunity to reduce patient radiation exposure across all world regions. 相似文献
4.
目的 分析医学生的学习风格特征,探讨不同的学习风格特征对腹腔镜扶镜助手技能训练的影响。方法 在腹腔镜扶镜助手扶镜技能训练前采用Kolb学习风格量表于2020年9月至12月对哈尔滨医科大学附属第四医院60名实习医生和40名专硕研究生学习风格特征进行评估;然后分析比较实习医生和专硕研究生学习风格特征的差异,以及不同学习风格特征对腹腔镜扶镜技能训练效果的影响。结果 实习医生和专硕研究生学习风格特征差异有统计学意义(P<0.001)。实习生群体中以发散型学习风格为主,研究生群体中以聚合型学习风格为主。学习风格特征对腹腔镜扶镜技能效果有显著影响。实习医生和专硕研究生聚合型学习风格受试者在扶镜技能训练中,视野居中、水平位、最佳视野每个周期平均失误数均明显少于发散、同化和调节型学习风格的受试者。结论 医学生中不同学习群体有着不同的学习风格特征。在腹腔镜扶镜技能训练中学习风格特征对训练效果有显著影响。医学教育中应该充分兼顾不同学习风格特征的特点,充分发挥学生学习风格优势。 相似文献
5.
Yasushi Yamasaki Keita Harada Shumpei Yamamoto Eriko Yasutomi Shotaro Okanoue Mami Hirai Shohei Oka Yuka Obayashi Hiroyuki Sakae Kenta Hamada Toshihiro Inokuchi Hideaki Kinugasa Yuusaku Sugihara Masahiro Takahara Takehiro Tanaka Sakiko Hiraoka Yoshiro Kawahara Hiroyuki Okada 《Digestive endoscopy》2020,32(5):791-800
6.
The leaves of Rubus suavissimus (also called “Chinese sweet tea”) is used not only as a beverage tea and food additive but also as a folk herbal medicine for the treatment of diabetes mellitus. To systematically investigate its material foundation of efficacy for treating diabetes, herein, a hyphenated strategy by off-line coupling high-speed countercurrent chromatography, ultrafiltration HPLC-UV-MS and prep-HPLC was developed. And thus, α-glucosidase inhibitors from Rubus suavissimus leaves was comprehensively profiled, purified and characterized. As a result, twenty-six compounds were identified as potential α-glucosidase inhibitors and favorably isolated by prep-HPLC. Their structures were identified via UV, MS, and 1H-NMR. Notably, fourteen compounds, including protocatechuic acid (1), myketin (3), epicatechin (4), vanillic acid (6), apigenin (11), catechin (12), ferulic acid (15), luteolin (16), 3, 3′-di-O-methylellagic acid (17), chlorogenic acid (19), 3, 3′-di-O-methylellagic acid-4′-O-β-D-glucoside (20), cinnamic acid (21), syringate (24) and ethylbrevifolin-carboxylate (25), were reported in leaves of Rubus suavissimus for the first time. In addition, α-glucosidase inhibitory activities of compounds 1–26 were evaluated, and eighteen compounds exhibited stronger α-glucosidase inhibitory activities than acarbose (IC50 value at 214.24 ± 3.48 μg/mL, positive control). The results indicated that the proposed method is a highly efficient strategy for comprehensive profiling and purification of bioactive target compounds, including both major and minor components, from natural products. 相似文献
7.
Weibo Sun Xuejiao Dong Dan Xu Jiajia Meng Xiaoxiang Fu Xiaohan Wang Daowan Lai Ligang Zhou Yang Liu 《Toxins》2016,8(1)
Ustilaginoidins are bis-naphtho-γ-pyrone mycotoxins isolated from the rice false smut balls (FSBs) infected by the pathogen Villosiclava virens in rice spikelets on panicles. In order to obtain large amounts of pure ustilaginoidins to further evaluate their biological activities and functions, phytotoxicity on rice, security to human and animals as well as to accelerate their applications as pharmaceuticals, preparative high-speed counter-current chromatography (HSCCC) was successfully applied to the isolation and purification of seven bis-naphtho-γ-pyrone mycotoxins, namely ustilaginoidins A (1), G (2), B (3), H (4), I (5), C (6), and J (7) from the ethyl acetate crude extract of rice FSBs. Both 1 and 2 were prepared by HSCCC from the low-polarity fraction of the crude extract using the two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water at the volume ratio of 6.5:3.5:5.0:5.0. Similarly, 3, 4 and 5 were prepared from the medium-polarity fraction using the system at the volume ratio of 4.0:5.0:5.0:6.0, and 6 and 7 were prepared from the higher-polarity fraction using the system at volume ratio of 3.0:5.0:4.0:6.7. A total of 6.2 mg of 1, 5.1 mg of 2, 3.9 mg of 3, 1.2 mg of 4, 5.7 mg of 5, 3.5 mg of 6, and 6.1 mg of 7 with purities of 88%, 82%, 91%, 80%, 92%, 81% and 83%, respectively, were yielded from total 62 mg fraction samples in three independent HSCCC runs. The structures of the purified ustilaginoidins were characterized by means of physicochemical and spectrometric analysis. 相似文献
8.
9.
《Gait & posture》2020
BackgroundSurface topography can be used for the evaluation of spinal deformities without any radiation. However, so far this technique is limited to posterior trunk measurements due to the use of a single posterior camera.Research questionPurpose of this study was to introduce a new multi camera surface topography system and to test its reliability and validity.MethodsThe surface topograph uses a two-camera system for imaging and evaluating the subjects front and back simultaneously. Inter- and intra-rater reliability was tested on 40 human subjects by two observers. For validation human, subjects were scanned by MRI and surface-topography. For additional validation we used a phantom with an anthropomorphic body which was scanned by CT and surface topography.ResultsInter- (0.97−0.99) and intra-rater reliability (0.81−0.98) testing revealed good and excellent results in the detection of the body surface structures and measurement of areas and volumes. CT based validation revealed good correspondence between systems in the imaging and evaluation of the phantom model (0.61–10.52 %). Results on validation of human subjects revealed good to moderate results in the detection and measurements of almost all body surface structures (1.36–13.34 %). Only measurements using jugular notch as a reference showed moderate results in validity (0.62–27.5%) testing.SignificanceWe have introduced a novel and innovative surface topography system that allows for simultaneous anterior and posterior trunk measurements. The results of our reliability and validity tests are satisfactory. However, in particular around the jugular notch region further improvements in the surface topography reconstruction are needed. 相似文献
10.