全文获取类型
收费全文 | 2130篇 |
免费 | 127篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 68篇 |
儿科学 | 48篇 |
妇产科学 | 85篇 |
基础医学 | 279篇 |
口腔科学 | 51篇 |
临床医学 | 143篇 |
内科学 | 368篇 |
皮肤病学 | 60篇 |
神经病学 | 224篇 |
特种医学 | 77篇 |
外科学 | 307篇 |
综合类 | 13篇 |
一般理论 | 1篇 |
预防医学 | 117篇 |
眼科学 | 36篇 |
药学 | 107篇 |
中国医学 | 5篇 |
肿瘤学 | 273篇 |
出版年
2022年 | 16篇 |
2021年 | 44篇 |
2020年 | 25篇 |
2019年 | 33篇 |
2018年 | 44篇 |
2017年 | 39篇 |
2016年 | 36篇 |
2015年 | 37篇 |
2014年 | 40篇 |
2013年 | 60篇 |
2012年 | 106篇 |
2011年 | 123篇 |
2010年 | 77篇 |
2009年 | 64篇 |
2008年 | 105篇 |
2007年 | 108篇 |
2006年 | 89篇 |
2005年 | 101篇 |
2004年 | 72篇 |
2003年 | 102篇 |
2002年 | 93篇 |
2001年 | 68篇 |
2000年 | 50篇 |
1999年 | 59篇 |
1998年 | 26篇 |
1997年 | 27篇 |
1996年 | 27篇 |
1995年 | 28篇 |
1994年 | 25篇 |
1993年 | 19篇 |
1992年 | 26篇 |
1991年 | 25篇 |
1990年 | 33篇 |
1989年 | 22篇 |
1988年 | 26篇 |
1987年 | 17篇 |
1986年 | 23篇 |
1985年 | 30篇 |
1984年 | 23篇 |
1983年 | 32篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1975年 | 16篇 |
1974年 | 18篇 |
1973年 | 14篇 |
1970年 | 12篇 |
排序方式: 共有2262条查询结果,搜索用时 15 毫秒
81.
Differentiation and long-term survival of C2C12 myoblast grafts in heart. 总被引:24,自引:7,他引:24
下载免费PDF全文
![点击此处可从《The Journal of clinical investigation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have assessed the ability of skeletal myoblasts to form long-term, differentiated grafts in ventricular myocardium. C2C12 myoblasts were grafted directly into the heart of syngeneic mice. Viable grafts were observed as long as 3 mo after implantation. Immunohistological analyses revealed the presence of differentiated myotubes that stably expressed the skeletal myosin heavy chain isoform. Thymidine uptake studies indicated that virtually all of the grafted skeletal myocytes were withdrawn from the cell cycle by 14 d after grafting. Graft myocytes exhibited ultrastructural characteristics typical of differentiated myotubes. Graft formation and the associated myocardial remodeling did not induce overt cardiac arrhythmia. This study indicates that the myocardium can serve as a stable platform for skeletal myoblast grafts. The long-term survival, differentiated phenotype, and absence of sustained proliferative activity observed in myoblast grafts raise the possibility that similar grafting approaches may be used to replace diseased myocardium. Furthermore, the genetic tractability of myoblasts could provide a useful means for the local delivery of recombinant molecules to the heart. 相似文献
82.
Pihl K Sørensen TL Nørgaard-Pedersen B Larsen SO Nguyen TH Krebs L Larsen T Christiansen M 《Prenatal diagnosis》2008,28(3):247-253
OBJECTIVE: To establish the relationship between the first-trimester screening markers [pregnancy-associated plasma protein A (PAPP-A), free human chorionic gonadotrophin-beta (beta-hCG), nuchal translucency (NT)], the Down syndrome (DS) risk estimate, and the adverse outcomes such as low birth weight, small for gestational age (SGA) and pre-term delivery. METHODS: A retrospective cohort study including 1,734 non-selected singleton pregnancies consecutively enrolled into the programme of first-trimester combined screening for DS in a 12-month period at a single centre. Data from the Prenatal Patient Registry in ASTRAIA were combined with the Danish National Newborn Screening Registry and Danish Birth Registry. RESULTS: There was a significant relation between low PAPP-A MoM, low beta-hCG MoM, increased risk estimate for DS and low birth weight and SGA. Low PAPP-A MoM and increased NT showed a significant relation to pre-term and spontaneous pre-term delivery. Low PAPP-A MoM showed a significant relation to early pre-term delivery. CONCLUSION: First-trimester screening markers exhibited a significant relation to low birth weight, SGA and to some extent, to pre-term and early pre-term delivery. The screening performance of individual markers was poor. 相似文献
83.
BACKGROUND: First-trimester maternal serum screening for Down syndrome (DS) can be improved by the use of additional serum markers. We examined whether progesterone (P), synthesized by placenta, might be a first-trimester maternal serum marker for fetal DS. MATERIALS AND METHODS: P was quantified in first-trimester maternal serum from 42 DS, six trisomy 18 and two trisomy 13 pregnancies and 115 controls. Log-regression of P versus gestational age in days was used to convert P concentrations into multiples of the median (MoM). RESULTS: The P concentrations in controls increased with gestational age (p = 9.5 x 10(-7)). The log10MoM P distribution in DS pregnancies was not significantly different from that in controls. However, from day 58-67, the log10MoM P was elevated in DS pregnancies (n = 10) with a mean (SD) of 0.1040 (0.0956), compared to a mean (SD) of - 0.0109 (0.1661) in controls (n = 24) (p = 0.05). Five out of six trisomy 18 and both trisomy 13 pregnancies had a P MoM < 1. CONCLUSION: P is not a useful marker for DS in first trimester, except perhaps in a narrow gestational age window from day 58 to 67. P is a trisomy 18/13 marker. 相似文献
84.
85.
86.
Gabrielle Notorgiacomo Justin Klug Scott Rapp Steven T. Boyce Stacey C. Schutte 《International wound journal》2022,19(3):633
Negative pressure wound therapy (NPWT) has become the prevailing standard of care for treating complex soft tissue wounds and is now being considered for use in alternative applications including improving skin graft take. While it is generally agreed that negative pressure leads to improved wound healing, universal consensus on its optimal application is not supported in the literature. We describe the design and validation of a bioreactor to determine the prospective benefits of NPWT on skin grafts and engineered skin substitutes (ESS). Clinically relevant pressures were applied, and the native human skin was able to withstand greater negative pressures than the engineered substitutes. Both skin types were cultured under static, flow‐only, and −75 mm Hg conditions for 3 days. While it remained intact, there was damage to the epidermal‐dermal junction in the ESS after application of negative pressure. The normal skin remained viable under all culture conditions. The engineered skin underwent apoptosis in the flow‐only group; however, the application of negative pressure reduced apoptosis. Vascular endothelial growth factor levels were significantly higher in the normal flow‐only group, 152.0 ± 75.1 pg/mg protein, than the other culture conditions, 81.6 ± 35.5 pg/mg for the static and 103.6 ± pg/mg for the negative pressure conditions. The engineered skin had a similar trend but the differences were not significant. This bioreactor design can be used to evaluate the impacts of NPWT on the anatomy and physiology of skin to improve outcomes in wounds after grafting with normal or engineered skin. 相似文献
87.
M. Rusan T. E. Klug T. Ovesen 《European journal of clinical microbiology & infectious diseases》2009,28(3):243-251
This study is the first to provide an extensive overview of the microbiology of acute ear, nose and throat infections requiring
hospitalisation. All 2,028 cases of acute infections admitted between 1 January 2001 and 31 December 2006 were reviewed to
assess the use of pre-admission antibiotics, microbiological results, antibiotic and surgical management and length of hospitalisation.
Infections of the oropharynx accounted for the vast majority of admissions, followed by ear infections, and cutaneous neck
abscesses. Peritonsillar abscess was the most frequent diagnosis, accounting for over one third of admissions (39.8%, 808
out of 2,028). Complete microbiological data were available for 1,430 cultures, and were analysed for trends with respect
to diagnosis, age, gender and use of pre-admission antibiotics. Forty-six percent (657 out of 1,430) of cultures yielded no
growth or normal flora. This value increased to 77.0% (298 out of 387) in patients with pre-admission antibiotics. The distribution
of microbiological isolates varied significantly between patients with and without pre-admission antibiotics, as well as with
respect to age and gender. The most frequently isolated bacteria were Group A Streptococcus (13.7%, 196 out of 1,430), Fusobacterium necrophorum (13.6%, 195 out of 1,428) and Staphylococcus aureus (8.0%, 114 out of 1,430). Fusobacterium necrophorum was primarily isolated from cases of peritonsillar abscess (90.8%, 177 out of 195). This study suggests that F. necrophorum is a far more widespread pathogen in otorhinolaryngology than previously reported, and questions the value of routine culturing,
as results rarely altered initial treatment. Further research on the microbiological variations with age and gender is recommended
to better target culturing and treatment, and enhance our understanding of the pathogenesis of ear, nose and throat infections. 相似文献
88.
Hanne Kristine Hegaard Peter Damm Morten Hedegaard Tine Brink Henriksen Bent Ottesen Anna-Karin Dykes Hanne Kjaergaard 《Maternal and child health journal》2011,15(6):806-813
To describe patterns of leisure time physical activity during pregnancy in relation to pre-pregnancy leisure time physical
activity, socio-demographic characteristics, fertility history, and lifestyle factors. 4,718 nulliparous with singleton pregnancy
and intended spontaneous vaginal delivery were included in the study at gestational week 33 from May 2004 to July 2005. Information
was provided by self-administered questionnaires. Leisure time physical activity was categorised into four categories: competitive
sport, moderate-to-heavy, light or sedentary. In this population of nulliparous women, 4% participated in competitive sport,
25% in moderate-to-heavy activities, 66% in light activities, and 5% in sedentary activities in the year prior to pregnancy.
Physical activity before pregnancy was statistically significantly associated with age, pre-pregnancy BMI, chronic diseases,
number of years at school, and smoking habits. The proportion of women who took part in competitive sports, and moderate-to-heavy
activities decreased over the three trimesters of pregnancy. The proportion of women with light physical activity was stable
during pregnancy while the proportion of women with sedentary activity increased from 6% to 29%. During the third trimester
women performing competitive sports or moderate-to-heavy activities before pregnancy continued to have a higher level of physical
activity than women with light activities or sedentary activities before pregnancy. In general the intensity and time spent
on exercise decreased during pregnancy. Women with the highest level of exercise prior to pregnancy continued to be the most
active during pregnancy. Among women with sedentary activities before pregnancy one-fourth changed to light activity during
pregnancy. 相似文献
89.
Joshua K. Herr Steven Keith Rick Klug Ronald J. Pettis 《Journal of diabetes science and technology》2014,8(4):850-854
In this study, the temperature profiles of insulin pump reservoirs during normal wear conditions across multiple seasons were characterized. Thermocouples secured in reservoirs filled with insulin diluent were loaded in infusion pumps worn by volunteers. Reservoir and ambient environmental temperature data and activity levels were logged during the course of normal daily activities in February (winter), April (spring), and August (summer). Each seasonal data set comprised 7 to 14 days of wear from 3 to 5 volunteers. Reservoir temperature profiles were generally higher than ambient temperatures, likely due to heat transfer from the wearer when the pump was placed close to the body. Temperature conditions inside pump reservoirs fluctuated between 25°C and 37°C regardless of seasonal variations. The average reservoir temperature remained close to 30°C across all seasons, notably lower than used in previously published compatibility and stability protocols (37°C). Results from this study could be utilized to develop more accurate stability and compatibility testing procedures for new insulin formulations and/or delivery devices. 相似文献
90.