首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2956篇
  免费   181篇
  国内免费   8篇
耳鼻咽喉   56篇
儿科学   111篇
妇产科学   61篇
基础医学   280篇
口腔科学   68篇
临床医学   292篇
内科学   587篇
皮肤病学   53篇
神经病学   226篇
特种医学   80篇
外科学   576篇
综合类   39篇
一般理论   2篇
预防医学   200篇
眼科学   62篇
药学   234篇
中国医学   4篇
肿瘤学   214篇
  2024年   4篇
  2023年   32篇
  2022年   71篇
  2021年   126篇
  2020年   83篇
  2019年   106篇
  2018年   123篇
  2017年   102篇
  2016年   94篇
  2015年   87篇
  2014年   116篇
  2013年   131篇
  2012年   251篇
  2011年   255篇
  2010年   122篇
  2009年   93篇
  2008年   175篇
  2007年   189篇
  2006年   158篇
  2005年   129篇
  2004年   139篇
  2003年   101篇
  2002年   107篇
  2001年   36篇
  2000年   25篇
  1999年   29篇
  1998年   16篇
  1997年   4篇
  1996年   21篇
  1995年   13篇
  1994年   7篇
  1993年   6篇
  1992年   25篇
  1991年   20篇
  1990年   12篇
  1989年   14篇
  1988年   20篇
  1987年   14篇
  1986年   9篇
  1985年   7篇
  1984年   6篇
  1983年   6篇
  1982年   6篇
  1981年   5篇
  1979年   9篇
  1975年   8篇
  1974年   4篇
  1971年   4篇
  1968年   5篇
  1965年   3篇
排序方式: 共有3145条查询结果,搜索用时 15 毫秒
1.
Pattern visual evoked potentials were obtained from 46 patients with definite relapsing/remitting multiple sclerosis, using both a conventional 5-channel occipital array and a 3-D recording technique consisting of three bipolar derivations approximating the three dimensions of space. These three orthogonal wave forms were displayed as a 3-D Lissajous trajectory for each subject. Two of the 15 patients with completely normal conventional pattern VEPs had abnormalities of the orientation of the B-C curvilinear segment of the 3-D pattern VEPs. Delays in the first major occipital positive component (P100) were evident using both techniques; the correlation between P100 latency and the latency of the corresponding trajectory apex was r = 0.99 (P less than 0.01). Post-chiasmal MRI abnormalities were associated with 3-D VEP orientation abnormalities. Three-dimensional pattern VEPs are moderately more sensitive than conventional pattern VEPs at detecting dysfunction posterior to the optic chiasm in demyelinating disease and do not require the use of eccentric fixation to do so.  相似文献   
2.
The Child and Adolescent Trial for Cardiovascular Health (CATCH) is a multisite intervention research study that builds on significant progress made in school health education research in the 1980s. The study has three phases: Phase I deals with study design, intervention, and measurement development, Phase II involves the main trial in 96 schools in four states, and Phase III focuses on analysis. The intervention program targets third-fifth grade students and focuses on multiple cardiovascular health behaviors, including eating habits, physical activity, and cigarette smoking. Classroom curricula, school environmental change, and family involvement programs are developed for each grade level and behavioral focus. This paper describes Phase II of CATCH with a rationale for cardiovascular health promotion with youth. The process of change that appears to be necessary for school-based health promotion and that will be tested in CATCH are presented as a framework to guide these efforts.  相似文献   
3.
4.
5.
To verify validity of a newly developed ultraminiature EMG measurement system (BMS), the ability of BMS to record masseteric EMG was compared with that of a conventional polygraph system (PG) in the daytime. Effective distance between the transmitter unit and receiver unit of BMS was also examined. Subjects were 12 healthy volunteers. During tapping, maximum clenching, and gum chewing of all subjects, distinct bursts were observed in EMG recorded by BMS as well as PG. RMS values of maximum clenching measured by BMS and PG showed a linear and significant correlation, and there was no significant difference between the data of BMS and PG. When distance between the transmitter unit and receiver unit of BMS was 100 cm or less, no artifact signal was observed. Having obtained these findings suggesting ability for precise measurement in the daytime, we are planning to use BMS in home sleep studies in the next step.  相似文献   
6.
7.
White Carneau pigeons were trained to discriminate 1.0 mg/kg buspirone from saline when key pecking was maintained under a fixed-ratio 30 schedule of food presentation. Buspirone (0.3-10.0 mg/kg), the serotonin 1A (5-HT(1A)) agonist 8-OH-DPAT (0.1-1mg/kg), the buspirone analog BMY 7378 (3.0-5.6mg/kg), the mixed 5-HT(1A/1B) agonist RU 24969 (3.0-10.0mg/kg) and the 5-HT(1A) agonist spiroxatrine (0.1-1.0mg/kg) occasioned at least 80% buspirone-appropriate responding in all subjects tested. Administration of the 5-HT(1B) agonist (TFMPP 0.1-10.0mg/kg) or the 5-HT(3) antagonist (MDL 72222 (3.0-17.0mg/kg) resulted in primarily saline-key responding. The dopamine receptor antagonist chlorpromazine (1.0-17.0mg/kg), the specific D-2 receptor antagonist eticlopride (0.03-0.56mg/kg), the noradrenergic alpha-2 antagonist yohimbine (0.1-1.0mg/kg), the alpha-2 agonist clonidine (0.003-0.10mg/kg) and (+/-) and (-) propranolol (3.0-30.0mg/kg) all produced primarily saline-appropriate responding. Coadministration of the beta-adrenergic agonist isoproterenol (1.0-5.6mg/kg) or the 5-HT(1A) partial agonist BMY 7378 (0.01-10.0mg/kg) with 1.0mg/kg buspirone did not block the discriminative stimulus effects of buspirone. However, 3.0-10.0mg/kg BMY 7378, in combination with a lower dose of buspirone (0.3mg/kg) decreased drug-key responding to approximately 50%. Results from the present study suggest that (1) the discriminative stimulus effects of buspirone, 8-OH-DPAT, BMY 7378, RU 24969 and spiroxatrine are mediated through the 5-HT(1A) receptor; (2) buspirone's discriminative stimulus effects do not interact with the noradrenergic or dopaminergic system; and 3) under this procedure BMY 7378 was a partial agonist at 5-HT(1A) receptors.  相似文献   
8.
An epicutaneous application of 2,4-dinitrofluorobenzene (DNFB) to a mouse ear caused a transient skin swelling, and the repetition of the challenge enlarged the contact dermatitis. The repeated challenge with DNFB also induced eosinophil infiltration on the application site. Administration of a chymase inhibitor significantly inhibited the ear swelling as well as eosinophil accumulation. An intradermal injection of human chymase to the mouse ear also elicited transient skin swelling and eosinophil infiltration, both of which were augmented in proportion to the number of injections. Human serum albumin and heat-inactivated chymase failed to induce such skin reactions, suggesting the participation of proteolytic activity of the enzyme. In addition, chymase stimulated eosinophil migration in vitro in a concentration-dependent manner. Taken together, these observations suggest that mast cell chymase may contribute to development of the DNFB-induced dermatitis, probably by promoting eosinophil infiltration. It is therefore possible that chymase plays a role in pathogenesis of chronic dermatitis such as atopic dermatitis.  相似文献   
9.
Determination of hepatitis C virus genotype by Pyrosequencing   总被引:4,自引:0,他引:4  
A simple sequencing-based assay is described for genotyping of hepatitis C virus (HCV). RT-PCR was employed to amplify a 237-nucleotide-long fragment from the 5' untranslated region (UTR) of the genome using one biotinylated and one normal primer. Subsequent to capture of the PCR products on streptavidin-coated beads, single-stranded DNA separation, and hybridization of sequencing primer, Pyrosequencing was performed. The genotype of 98 samples out of which 77 samples were from American veterans and 21 samples were from Iran was determined. The samples from the American veterans contained six different subtypes, while five subtypes were found in Iranian samples. For rapid population-specific HCV subtyping, a multiplex assay was developed. This study demonstrates the suitability of this technology for low-cost, high throughput and accurate microbial genotyping.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号