全文获取类型
收费全文 | 22149篇 |
免费 | 1602篇 |
国内免费 | 351篇 |
专业分类
耳鼻咽喉 | 186篇 |
儿科学 | 506篇 |
妇产科学 | 415篇 |
基础医学 | 2552篇 |
口腔科学 | 759篇 |
临床医学 | 3227篇 |
内科学 | 5415篇 |
皮肤病学 | 1313篇 |
神经病学 | 995篇 |
特种医学 | 508篇 |
外国民族医学 | 2篇 |
外科学 | 2219篇 |
综合类 | 1620篇 |
一般理论 | 5篇 |
预防医学 | 1765篇 |
眼科学 | 181篇 |
药学 | 1578篇 |
8篇 | |
中国医学 | 166篇 |
肿瘤学 | 682篇 |
出版年
2024年 | 44篇 |
2023年 | 496篇 |
2022年 | 1486篇 |
2021年 | 1702篇 |
2020年 | 1207篇 |
2019年 | 1000篇 |
2018年 | 914篇 |
2017年 | 842篇 |
2016年 | 806篇 |
2015年 | 858篇 |
2014年 | 1285篇 |
2013年 | 1671篇 |
2012年 | 990篇 |
2011年 | 1073篇 |
2010年 | 888篇 |
2009年 | 854篇 |
2008年 | 843篇 |
2007年 | 821篇 |
2006年 | 696篇 |
2005年 | 579篇 |
2004年 | 535篇 |
2003年 | 463篇 |
2002年 | 420篇 |
2001年 | 339篇 |
2000年 | 295篇 |
1999年 | 316篇 |
1998年 | 276篇 |
1997年 | 282篇 |
1996年 | 232篇 |
1995年 | 207篇 |
1994年 | 190篇 |
1993年 | 155篇 |
1992年 | 192篇 |
1991年 | 142篇 |
1990年 | 118篇 |
1989年 | 124篇 |
1988年 | 109篇 |
1987年 | 99篇 |
1986年 | 64篇 |
1985年 | 99篇 |
1984年 | 84篇 |
1983年 | 54篇 |
1982年 | 55篇 |
1981年 | 42篇 |
1980年 | 46篇 |
1979年 | 33篇 |
1978年 | 13篇 |
1977年 | 18篇 |
1976年 | 25篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
2 mg/kg melanotan II (MTII, administered i.p.), a cyclic peptide analog of α-melanocyte stimulating hormone, at a single dose increased grooming in naive rats placed in an unfamiliar open-field device without changing locomotion or rearing. Male rats exposed to restraint/immobilization stress (IS) for 1 h on three consecutive days displayed increased grooming after the second stressor exposure, compared to pre-stress levels. MTII, administered to the rats after IS, enhanced the grooming response compared both to the pre- and post-stress values. The increase was greatest after the first dose and declined over the following two applications. As to the locomotion of rats in the entire experimental space, IS reduced the distance moved only after the first two stressor exposures; MTII did not influence these alterations. Locomotion in the central part of arena was not reduced by the stressor or by MTII, on the contrary, there was an increase in both groups after the third intervention. The only observed change in rearing was an increase in the MTII group after the third restraint exposure. Thus, MTII selectively increased grooming without markedly affecting the spatio-temporal structure of locomotor behavior in the open-field. The decline of MTII enhanced grooming over the three test days may be interpreted in terms of adaptation to the stressor and of the developing tolerance to the peptide. 相似文献
92.
Reliability and validity of the Biodex system 3 pro isokinetic dynamometer velocity,torque and position measurements 总被引:1,自引:1,他引:1
Drouin JM Valovich-mcLeod TC Shultz SJ Gansneder BM Perrin DH 《European journal of applied physiology》2004,91(1):22-29
This study quantitatively assessed the mechanical reliability and validity of position, torque and velocity measurements of the Biodex System 3 isokinetic dynamometer. Trial-to-trial and day-to-day reliability were assessed during three trials on two separate days. To assess instrument validity, measurement of each variable using the Biodex System 3 dynamometer was compared to a criterion measure of position, torque and velocity. Position was assessed at 5° increments across the available range of motion of the dynamometer. Torque measures were assessed isometrically by hanging six different calibrated weights from the lever arm. Velocity was assessed (30°/s to 500°/s) across a 70° arc of motion by manually accelerating the weighted lever arm. With the exception of a systematic decrease in velocity at speeds of 300°/s and higher, the Biodex System 3 performed with acceptable mechanical reliability and validity on all variables tested.DisclosureThe Biodex dynamometer used for this investigation was donated to the laboratory by Biodex Medical Systems. The authors have no commercial or proprietary interest in this device. 相似文献
93.
V. Kvedariene P. Martins L. Rouanet P. Demoly 《Clinical and experimental allergy》2006,36(8):1072-1077
Background Iodinated contrast media (ICM) hypersensitivity reactions represent a serious problem. Very few clinical data concerning systematic skin testing to ICM are available. Objective To evaluate the utility of ICM skin testing in patients with ICM hypersensitivity. Material and methods All patients referred over a 6‐year period for ICM hypersensitivity past reactions were skin tested for (a) the implicated ICM, or (b) a set of ICM if they were positive for the implicated ICM or if its name was unknown. Results Forty‐four patients, with a median age of 56 years, were studied (15 males, 29 females). The ICM skin tests were positive in 10 patients (23%): one had a positive skin prick test, seven an immediate positive intradermal test (IDT) and two a delayed positive IDT. Skin tests were more often positive in patients with immediate (9/32) as compared with those with non‐immediate reactions (1/11). The time interval between the reaction and skin testing was shorter for those patients with an immediate ICM reaction and a positive skin test result (3 months [2.5–174.0]) as compared with those with an immediate ICM reaction and a negative skin test (48 months [6.8–159.0]), (P<0.05). Respiratory allergy was more frequent in the positive group (6/10 vs. 7/34, P<0.05). Conclusions Skin tests with ICM are positive in a subgroup of patients with ICM hypersensitivity and may play an important role in the diagnosis of ICM allergy. 相似文献
94.
Kerry E. Goetz Melissa J. Reeves Shaina Gagadam Delphine Blain Chelsea Bender Cara Lwin Amelia Naik Santa J. Tumminia Robert B. Hufnagel 《American journal of medical genetics. Part C, Seminars in medical genetics》2020,184(3):828-837
Genetic testing in a multisite clinical trial network for inherited eye conditions is described in this retrospective review of data collected through eyeGENE®, the National Ophthalmic Disease Genotyping and Phenotyping Network. Participants in eyeGENE were enrolled through a network of clinical providers throughout the United States and Canada. Blood samples and clinical data were collected to establish a phenotype:genotype database, biorepository, and patient registry. Data and samples are available for research use, and participants are provided results of clinical genetic testing. eyeGENE utilized a unique, distributed clinical trial design to enroll 6,403 participants from 5,385 families diagnosed with over 30 different inherited eye conditions. The most common diagnoses given for participants were retinitis pigmentosa (RP), Stargardt disease, and choroideremia. Pathogenic variants were most frequently reported in ABCA4 (37%), USH2A (7%), RPGR (6%), CHM (5%), and PRPH2 (3%). Among the 5,552 participants with genetic testing, at least one pathogenic or likely pathogenic variant was observed in 3,448 participants (62.1%), and variants of uncertain significance in 1,712 participants (30.8%). Ten genes represent 68% of all pathogenic and likely pathogenic variants in eyeGENE. Cross‐referencing current gene therapy clinical trials, over a thousand participants may be eligible, based on pathogenic variants in genes targeted by those therapies. This article is the first summary of genetic testing from thousands of participants tested through eyeGENE, including reports from 5,552 individuals. eyeGENE provides a launching point for inherited eye research, connects researchers with potential future study participants, and provides a valuable resource to the vision community. 相似文献
95.
96.
本文研究了骨水泥三种不同临床使用方法所形成的内部气泡结构状态,测定了骨水泥的抗压强度、收缩率、疲劳强度、变形积累量等物理机械性能,以及关节固定强度,用气泡状态解释了不同临床使用方法对骨水泥性能及固定强度所带来的各种影响。 相似文献
97.
An acoustical technique has been developed for the measurement of structural symmetry of the hip joints. A mild vibratory force was applied to the sacrum and sound signals were picked up at both hips by a pair of microphones installed in two stethoscopes. These stethoscope–microphone assembles were calibrated to achieve a difference in relative sensitivity of less than 0.2 dB. The relative transmission of sound signals was analysed and compared between both hips by a dual-channel signal analyser. Twenty-seven healthy adults, 20 healthy pre-school children and 19 normal neonates were tested. Results from these three groups showed high coherence of the sound signals and that the discrepancy between both hips was smallest in the frequency range of 200–315 Hz. For normal neonates, the sound signals maintained a high coherence (γ2>0.97) and small discrepancy (D<1.25 dB) between both hips. This study has shown that the acoustical technique provides a practical structural testing for bony symmetry of the hips and the results offer a baseline for further investigation into developmental dysplasia of the hip (DDH) in neonates. Clinical screening for DDH is still problematic in developing countries. 相似文献
98.
模拟人体体温下对超高分子量聚乙烯(UHMWPE)人工髋臼材料进行了压缩力学性能的试验研究,并与室温下的试验结果进行了对比.当由室温22℃升高到体温37℃和40℃时,其屈服应力呈明显的下降趋势,分别下降了23.1%和31.9%,由体温37℃升高到40℃时,二者仅差3℃,其屈服应力亦下降了11.5%.同时还对不同加载速度下UHMWPE试件压缩变形过程进行了红外辐射温度的监测与分析.不同加载速度下试件压缩变形过程中的红外辐射温度均有明显升高,加载时间越长,试件平均红外辐射温度越高.试验结果分析表明,不能忽视植入人体后UHMWPE人工髋臼局部受压时温度的升高,特别不能忽视植入人体后在人体体温作用下其力学性能的改变和下降,人体体温的作用是UHMWPE人工髋臼出现过早失效的原因之一.本试验研究为UHMWPE材料在人体环境中的应用研究提供了参考. 相似文献
99.
Guodong Chen Shuxue Zhou Guangxin Gu Limin Wu 《Macromolecular chemistry and physics.》2005,206(8):885-892
Summary: Silica sols were first prepared based on different ratios of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) by an acid‐catalyzed sol–gel process, and then incorporated into acrylic‐based polyurethanes. The structures and morphologies of silicone‐oxo clusters were studied by 29Si NMR, SAXS, and scanning electron microscopy (SEM), whereas the mechanical properties of polyurethane/silica hybrids were characterized by DMA and tensile tests. The silicone‐oxo clusters in both silica sol and polyurethane hybrids became denser and larger at a higher molar ratio of TEOS/MTES and higher silica content, and the silica‐oxo clusters of polyurethane/silica hybrids even became more compact and larger than those of silica sols, increasing the elastic modulus and tensile strength of polyurethane/silica hybrids.
100.
Jagdish Butany Manmeet S. Ahluwalia Craig Munroe Cristina Fayet Christina Ahn Patrick Blit Charis Kepron Roberto J. Cusimano Richard L. Leask 《Cardiovascular pathology》2003,12(6):322-344
Mechanical heart value prostheses have been in use since the 1950s. Many prostheses have been used for a while and then discontinued. Today, there are a large number and variety of prostheses in use and an even larger variety that are in place in patients. These may be explanted at any time for a number of reasons. It is essential for the practicing pathologist to be able to identify the prosthesis and be aware of some of its reported complications and modes of failure. This article, and a second one on bioprosthetic heart valves, is designed as a ready reference guide to heart valve prostheses, their important identifying features, their common complications, and modes of failure. It should help in the accurate identification of explanted prosthetic valves and more definitive reports. This accuracy of identification as well as tracking of abnormalities noted will, we hope, permit the identification of new failure modes and the recording of causes of failure of new (or even modified) prosthetic heart valves. 相似文献