全文获取类型
收费全文 | 5851篇 |
免费 | 543篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 45篇 |
儿科学 | 202篇 |
妇产科学 | 106篇 |
基础医学 | 1000篇 |
口腔科学 | 67篇 |
临床医学 | 949篇 |
内科学 | 918篇 |
皮肤病学 | 31篇 |
神经病学 | 624篇 |
特种医学 | 103篇 |
外科学 | 541篇 |
综合类 | 138篇 |
一般理论 | 3篇 |
预防医学 | 813篇 |
眼科学 | 92篇 |
药学 | 416篇 |
中国医学 | 17篇 |
肿瘤学 | 336篇 |
出版年
2022年 | 67篇 |
2021年 | 87篇 |
2020年 | 81篇 |
2019年 | 89篇 |
2018年 | 116篇 |
2017年 | 91篇 |
2016年 | 97篇 |
2015年 | 89篇 |
2014年 | 129篇 |
2013年 | 239篇 |
2012年 | 295篇 |
2011年 | 350篇 |
2010年 | 201篇 |
2009年 | 158篇 |
2008年 | 298篇 |
2007年 | 376篇 |
2006年 | 349篇 |
2005年 | 370篇 |
2004年 | 300篇 |
2003年 | 311篇 |
2002年 | 306篇 |
2001年 | 94篇 |
2000年 | 92篇 |
1999年 | 91篇 |
1998年 | 73篇 |
1997年 | 78篇 |
1996年 | 46篇 |
1995年 | 59篇 |
1994年 | 56篇 |
1993年 | 43篇 |
1992年 | 52篇 |
1991年 | 58篇 |
1990年 | 50篇 |
1989年 | 58篇 |
1988年 | 44篇 |
1987年 | 42篇 |
1986年 | 56篇 |
1985年 | 55篇 |
1984年 | 54篇 |
1983年 | 49篇 |
1982年 | 67篇 |
1981年 | 57篇 |
1980年 | 55篇 |
1979年 | 41篇 |
1978年 | 44篇 |
1976年 | 47篇 |
1975年 | 43篇 |
1974年 | 48篇 |
1973年 | 39篇 |
1971年 | 39篇 |
排序方式: 共有6401条查询结果,搜索用时 0 毫秒
11.
The interaction between ciprofloxacin and vancomycin against nine isolates of Staphylococcus epidermidis from cases of infective endocarditis and three strains of S. aureus was studied. Killing curves indicated the presence of antagonism in the early stages, the clinical significance of which is uncertain. No synergy was found and the combination therefore does not appear to offer any advantages over vancomycin alone for the treatment of staphylococcal infections. 相似文献
12.
13.
Rhythmic bursting of pre- and post-inspiratory neurones during central apnoea in mature mice 总被引:2,自引:1,他引:1
Julian F. R. Paton 《The Journal of physiology》1997,502(3):623-639
14.
Pelvic ultrasound is a widely used diagnostic tool and accessto this investigation is not universally available to all generalpractitioners (GPs). The aim of this study was to assess ifGPs working in the United Arab Emirates (UAE) were using pelvicultrasound appropriately by determining the rates of diagnosticyield and referral after the investigation. It was then ascertainedif these results were affected by the post-graduate trainingor gender of the doctor. The subjects were adult females whohad had a pelvic ultrasound ordered by a GP over a 2-month period.A chart review determined the presenting complaint, the completenessof the request form, the result of the ultrasound and subsequentmanagement of the patient. Diagnostic yields and referral rateswere similar to those found in other studies and were unaffectedby the post graduate training or gender of the doctor or theamount of information contained in the request form. This studysupports the premise that GPs can use pelvic ultrasound appropriatelyand should be allowed free access to this investigation. 相似文献
15.
The random amplification of polymorphic DNA (RAPD method), was used to derive fragments of DNA of the coccidial parasiteEimeria tenella for use both as genetic markers and as an aid for the discrimination of different wild-type and attenuated populations. Of
41 arbitrarily chosen 9-to 27-mer primers, 24 yielded useful arrays of fragments following low-stringency annealing conditions
and the resultant profiles were generally very reproducible. One non-variant fragment of 2 kb hybridised to a single chromosome
(number 12) and four variant fragments were identified. These results strongly suggest that the RAPD method may be an extremely
useful tool for studies on various aspects of the genetic organisation of coccidial parasites. 相似文献
16.
17.
Shirley Kobar Coni C Francis Samantha MaWhinney Teresa Sharp 《Nutrition in clinical practice》2003,18(5):417-421
BACKGROUND: Development of an acclimation protocol for use when measuring resting energy expenditure (REE) would simplify and standardize data collection. The purpose of this study was to determine if our 2 metabolic carts could be used interchangeably and to determine if excluding the first 3 or 5 minutes of data collected as an acclimation period would significantly improve the coefficients of variation (CVs) for oxygen consumed (VO(2)) and carbon dioxide produced (VCO(2)) when performing REE assessments with our metabolic cart systems. METHODS: Thirteen healthy, nonsmoking adults ranging in age from 32 to 45 years, with activity levels ranging from sedentary to highly active, participated. Indirect calorimetry was performed twice in the morning after 30 minutes of supine resting. Subjects had fasted for 12 hours, and did not exercise within the last 24 hours. The system order for testing was randomized for the first measurement. When the first measurement was completed, subjects were crossed over for measurement using a second metabolic cart. RESULTS: The CVs for VO(2) and VCO(2) were significantly lower when excluding the first 3 (VO(2), p = .0005), (VCO(2), p = .0024) or 5 minutes (VO(2), p = .0001, VCO(2), p = .0021) of data compared with no exclusions. No significant differences in CVs between the 3- and 5-minute exclusions were found for VO(2) (p = .3224) or VCO(2) (p = .2255). CONCLUSIONS: Clearly, our machines cannot be used interchangeably within a study. An acclimation period improves CVs of VO(2) and VCO(2.) The similarities in CVs led us to adopt a 3-minute acclimation period for measuring REE. 相似文献
18.
Alfred S. Friedman Shirley Bransfield Cheryl Kreisher 《The American journal on addictions / American Academy of Psychiatrists in Alcoholism and Addictions》1994,3(4):325-336
The authors report on the relationship of early adolescent substance use (up to the time of the 16th birthday) to educational-vocational performance in the early adulthood of 612 African-American urban subjects. Voluminous prospective data were available on the behavior, test performance, and families of 612 urban African-American subjects, from birth up to 7 years of age. Scarcer prospective data were available for school performance during later years of school. Control variables were derived from these data to determine the amount of variance in each dependent educational-vocational outcome variable that was accounted for, independently of the amount of variance accounted for by early substance use. (American Journal on Addictions 1994; 3:325–336) 相似文献
19.
Joaquín Martí M.C. Santa-Cruz Shirley A. Bayer Bernardino Ghetti Jos P. Hervs 《International journal of developmental neuroscience》2007,25(5):299-307
Generation and survival of midbrain dopaminergic (DA) neurons were investigated using tyrosine hydroxylase (TH) immunocytochemistry combined with tritiated thymidine autoradiography at appropriate anatomical levels throughout the anteroposterior (A/P) axes of the substantia nigra pars compacta (SNc) and the ventral tegmental area (VTA). The wild-type (+/+) and homozygous weaver (wv/wv) mice used here were the offspring of pregnant dams injected with the radioactive precursor when the mesencephalic neurons were being produced (gestational days 11-15). Data reveal that, at postnatal day 90, depletion of TH-stained cells in the wv/wv presented an A/P pattern of increasing severity and, therefore, the DA cells located in posterior parts of the SNc or the VTA appear to be more vulnerable than the settled anterior neurons. When the time of neuron origin is inferred for each level of these cell groups, it is found that the neurogenesis span is similar for both experimental groups, although significant deficits in the frequency of wv/wv late-generated neurons were observed in any level considered. On the other hand, it has been found that TH-positive neurons were settled along the extent of the SNc and the VTA following precise and differential neurogenetic gradients. Thus, the acute rostrocaudal increase in the proportion of late-generated neurons detected in both+/+DA-cell groups is disturbed in the weaver homozygotes due to the indicated A/P depletion. 相似文献
20.