全文获取类型
收费全文 | 3532篇 |
免费 | 283篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 142篇 |
儿科学 | 142篇 |
妇产科学 | 70篇 |
基础医学 | 387篇 |
口腔科学 | 66篇 |
临床医学 | 412篇 |
内科学 | 523篇 |
皮肤病学 | 24篇 |
神经病学 | 361篇 |
特种医学 | 240篇 |
外科学 | 599篇 |
综合类 | 71篇 |
一般理论 | 2篇 |
预防医学 | 345篇 |
眼科学 | 50篇 |
药学 | 188篇 |
中国医学 | 2篇 |
肿瘤学 | 215篇 |
出版年
2023年 | 18篇 |
2022年 | 21篇 |
2021年 | 52篇 |
2020年 | 37篇 |
2019年 | 74篇 |
2018年 | 79篇 |
2017年 | 70篇 |
2016年 | 75篇 |
2015年 | 77篇 |
2014年 | 109篇 |
2013年 | 129篇 |
2012年 | 190篇 |
2011年 | 206篇 |
2010年 | 122篇 |
2009年 | 117篇 |
2008年 | 174篇 |
2007年 | 231篇 |
2006年 | 213篇 |
2005年 | 168篇 |
2004年 | 161篇 |
2003年 | 162篇 |
2002年 | 156篇 |
2001年 | 67篇 |
2000年 | 67篇 |
1999年 | 80篇 |
1998年 | 55篇 |
1997年 | 52篇 |
1996年 | 39篇 |
1995年 | 39篇 |
1994年 | 37篇 |
1993年 | 32篇 |
1992年 | 40篇 |
1991年 | 42篇 |
1990年 | 39篇 |
1989年 | 49篇 |
1988年 | 50篇 |
1987年 | 45篇 |
1986年 | 49篇 |
1985年 | 42篇 |
1984年 | 31篇 |
1983年 | 39篇 |
1982年 | 27篇 |
1981年 | 31篇 |
1980年 | 25篇 |
1979年 | 21篇 |
1978年 | 14篇 |
1977年 | 16篇 |
1976年 | 13篇 |
1970年 | 12篇 |
1969年 | 13篇 |
排序方式: 共有3839条查询结果,搜索用时 15 毫秒
41.
Background: this study was designed to characterize some of the biochemical and molecular genetic changes during reversion
of human fat cells. Methods: mature adipocytes were isolated from greater omental fat tissue of eight lean and 14 massively
obese persons by established methodology. Results: at day 7 of adherence to Leighton tubes, there was appreciable depletion
of triacylglycerol, as well as assumption of an elongated contour. Relatedly, there was an increase in the expression of β-actin
mRNA and a significant decrease in the specific activity of cytosolic glycerophosphate dehydrogenase. The decrement in the
specific activity of glycerophosphate dehydrogenase, after 7 days in culture, was significant at p < 0.001. Basic fibroblast growth factor at 10 ngml-1 accelerated significantly (p < 0.03) the decrease in the specific activity of glycerophosphate dehydrogenase in adipose cells from lean subjects. In contrast,
basic fibroblast growth factor had no significant influence on cells from massively obese persons. Conclusion: such resistance
may contribute to the intractability of massive obesity. 相似文献
42.
Brain R. West Harry Applebaum Bradford W. Edgerton 《Pediatric surgery international》1994,9(4):301-303
The most common approach to the pepair of pectus excavatum and pectus carinatum deformities is via a central transverse submammary incision. The subsequent suprasternal scar is conspicuous and prone to hypertrophic and keloid scarring. To avoid the keloid triangle and to produce a less noticeable scar, we have utilized bilateral inframammary incisions for repairs of five female and two male patients with pectus defects. This approach provides excellent access for cartilage resection, sternotomy, and sternal tupport without increasing opearative time or compromising operative exposure. On follow-up for up to 25 months, all patients have had excellent cosmetic and functional results. Chest wall configuration and stability, wound healing, and scar formation have all been without complication. No keloid or hypertrophic scars have developed. To date, there has been no recurrence of pectus defects. We believe bilateral inframammary incisions are a superior approach for pectus repairs by enchancing cosmesis with less noticeable scars and fewer hypertropic and keloid scars, all without compromising operative exposure or increasing operative time. 相似文献
43.
Pathways to care for alcohol use disorders 总被引:1,自引:0,他引:1
44.
45.
Oxidative stress occurs in perfused rat liver at low oxygen tension by mechanisms involving peroxynitrite 总被引:2,自引:0,他引:2
Arteel GE Kadiiska MB Rusyn I Bradford BU Mason RP Raleigh JA Thurman RG 《Molecular pharmacology》1999,55(4):708-715
Ethanol increases free radical formation; however, it was recently demonstrated that it also causes extensive hypoxia in rat liver in vivo. To address this issue, it was hypothesized that peroxynitrite formed in normoxic periportal regions of the liver lobule has its reactivity enhanced in hypoxic pericentral regions where the pH is lower. Via this pathway, peroxynitrite could lead to free radical formation in the absence of oxygen. Livers from fed rats were perfused at low flow rates for 75 min. Under these conditions, periportal regions were well oxygenated but pericentral areas became hypoxic. Low-flow perfusion caused a significant 6-fold increase in nitrotyrosine accumulation in pericentral regions. During the last 20 min of perfusion, the spin-trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone was infused and adducts were collected for electron-spin resonance analysis. A six-line radical adduct signal was detected in perfusate. Direct infusion of peroxynitrite produced a radical adduct with identical coupling constants, and a similar pattern of nitrotyrosine accumulation was observed. Retrograde perfusion at low rates resulted in accumulation of nitrotyrosine in periportal regions. Although the magnitude of the radical in perfusate was increased by ethanol, it was not derived directly from it. Both nitrotyrosine accumulation and radical formation were reduced by inhibition of nitric oxide synthase with N-nitro-L-arginine methyl ester, but not with the inactive D-isomer. Radical formation was decreased nearly completely by superoxide dismutase and N-nitro-L-arginine methyl ester, consistent with the hypothesis that the final prooxidant is a derivative from both NO. and superoxide (i.e., peroxynitrite). These results support the hypothesis that oxidative stress occurs in hypoxic regions of the liver lobule by mechanisms involving peroxynitrite. 相似文献
46.
Hamilton BS 《Obesity surgery》1996,6(1):7-11
In vitro investigations into adipose cell dynamics have revealed intrinsic characteristics of massively obese individuals' cells that
could contribute to a relatively intractable expanded fat mass. Morbidly corpulent peoples' preadipocytes replicate to a greater
degree than those from lean individuals. Coupled with exaggerated differentiation this enhanced growth would result in a greater
number of fat cells which would increase adipose tissue mass. The relative resistance to de-differentiation that adipocytes
from the massively obese demonstrate would contribute to stability of an increased number of adipocytes further exacerbating
the problem. The increased message of an energy sensing protein, the obese gene product, suggests that the morbidly obese are insensitive to its action. Together these attributes provide a strong
argument for a significant genetic role in the pathogenesis of obesity. 相似文献
47.
48.
STUDY DESIGN: A retrospective review of a clinical series was performed. OBJECTIVES: To evaluate the incidence of adult patients who experienced spinal collapse after spinal implant removal after a long spinal arthrodesis, and to assess the various factors that may influence the likelihood of collapse after implant removal. SUMMARY OF BACKGROUND DATA: Published reports describing the benefits or complications of spinal implant removal do not exist. Spinal implant removal, often considered a benign procedure, is even required by the Food and Drug Administration (FDA) for certain implants. METHODS: The medical records and radiographs of 116 consecutive adult patients with long posterior instrumented fusions (>5 segments) were reviewed. The information obtained included original diagnosis, patient age, number of previous surgeries before implant removal, levels of anterior and posterior fusion, time from fusion to implant removal, time from implant removal to failure, and reason for hardware removal. Radiographs also were assessed including scoliosis, lordosis, and kyphosis measurements before implant removal, after hardware removal, after failure, and after revision surgery. RESULTS: Of 116 patients, 14 underwent spinal implant removal. Most of these patients reported prominent implants either proximally in the thoracic spine or distally in the ilium (Galveston technique). Of these 14 patients, 4 experienced increased pain and collapse after implant removal despite thorough intraoperative explorations demonstrating solid fusion. CONCLUSIONS: Spinal implant removal after long posterior fusion in adults may lead to spinal collapse and further surgery. Removal of instrumentation should be avoided or should involve partial removal of the prominent implant. 相似文献
49.
50.