全文获取类型
收费全文 | 76405篇 |
免费 | 5428篇 |
国内免费 | 210篇 |
专业分类
耳鼻咽喉 | 615篇 |
儿科学 | 2210篇 |
妇产科学 | 1280篇 |
基础医学 | 10397篇 |
口腔科学 | 1611篇 |
临床医学 | 8061篇 |
内科学 | 16141篇 |
皮肤病学 | 1006篇 |
神经病学 | 7187篇 |
特种医学 | 2416篇 |
外国民族医学 | 1篇 |
外科学 | 10955篇 |
综合类 | 953篇 |
一般理论 | 76篇 |
预防医学 | 6903篇 |
眼科学 | 1830篇 |
药学 | 5218篇 |
1篇 | |
中国医学 | 93篇 |
肿瘤学 | 5089篇 |
出版年
2023年 | 449篇 |
2022年 | 637篇 |
2021年 | 1660篇 |
2020年 | 968篇 |
2019年 | 1562篇 |
2018年 | 1864篇 |
2017年 | 1398篇 |
2016年 | 1531篇 |
2015年 | 1773篇 |
2014年 | 2589篇 |
2013年 | 3462篇 |
2012年 | 5635篇 |
2011年 | 5766篇 |
2010年 | 3209篇 |
2009年 | 2832篇 |
2008年 | 5143篇 |
2007年 | 5573篇 |
2006年 | 5486篇 |
2005年 | 5180篇 |
2004年 | 4943篇 |
2003年 | 4460篇 |
2002年 | 4334篇 |
2001年 | 619篇 |
2000年 | 438篇 |
1999年 | 674篇 |
1998年 | 926篇 |
1997年 | 774篇 |
1996年 | 667篇 |
1995年 | 630篇 |
1994年 | 503篇 |
1993年 | 481篇 |
1992年 | 390篇 |
1991年 | 346篇 |
1990年 | 288篇 |
1989年 | 264篇 |
1988年 | 280篇 |
1987年 | 247篇 |
1986年 | 251篇 |
1985年 | 253篇 |
1984年 | 319篇 |
1983年 | 344篇 |
1982年 | 392篇 |
1981年 | 377篇 |
1980年 | 349篇 |
1979年 | 212篇 |
1978年 | 249篇 |
1977年 | 197篇 |
1976年 | 142篇 |
1975年 | 106篇 |
1974年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Stephen R. Thomas Ronald G. Pratt Ronald W. Millard R. C. Samaratunga Yoseph Shiferaw Leland C. Clark Richard E. Hoffmann 《Journal of magnetic resonance imaging : JMRI》1994,4(4):631-635
Oxygen-sensitive F-19 magnetic resonance imaging of perfluorocarbon compounds requires that fluorocarbon T1 changes correlate with the local Po2 and not with the composition of the surrounding aqueous phase. The influence of various bioconstituents and paramagnetic ions within the aqueous phase on the F-19 fluorocarbon phase T1 for PFC emulsions was evaluated at 0.14 and 0.66 T. T1 was measured for FC-43, perflubron, and a fluorinated surfactant. Controlled variables introduced in the aqueous phase included annex solution constituents, blood, pH changes, and Gd-DTPA. For a constant Po2, the F-19 T1s were independent of the emulsion constituents, blood concentration, and pH. For FC-43 and perflubron, F-19 T1 was independent of the Gd-DTPA concentration, while the aqueous phase T1 decreased by more than an order of magnitude. XMO-10 (smallest emulsion particle size) showed a slight decrease in F-19 T1 with increasing Gd-DTPA concentration at 0.66 T. 相似文献
52.
53.
Sarah A. Taylor Jacqueline Benedetti David Schuller Stephen P. Richman Goronwy O. Broun Alexander Hantel 《Investigational new drugs》1993,11(2-3):227-229
Summary Twenty-two patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with piroxantrone 150 mg/m2 intravenously every 21 days. There were no objective responses. The 95% upper confidence bound for response is 15%. Primary toxicity was hematologic. 相似文献
54.
55.
56.
57.
Joseph M Dhahbi Shelley X Cao Patricia L Mote Brian C Rowley John E Wingo Stephen R Spindler 《The Journal of nutrition》2002,132(1):31-37
Molecular chaperones assist in the biosynthesis and processing of proteins. Most chaperones are induced by physiological stresses. We have shown that dietary energy restriction decreases the mRNA and protein levels of many endoplasmic reticulum chaperones in the livers of mice. Here, we have investigated the response of chaperone mRNA to feeding. Control and 50% energy-restricted C3B10RF1 mice were deprived of food for 24 h, fed, and killed 0, 1.5, 5 or 12 h after feeding. Chaperone mRNAs were strongly induced as early as 1.5 h after feeding in control and energy-restricted mice. The integrated levels of these mRNA over 24 h were significantly lower in energy-restricted mice. The mRNA response to energy intake was mirrored over the course of days in the level of chaperone protein. A similar but smaller response to feeding was found in kidney and muscle. Puromycin and cycloheximide failed to inhibit the feeding response, suggesting that feeding releases chaperone expression from an unstable inhibitor. Studies with dibutyryl-cAMP- and glucagon-supplemented, normal and streptozotocin-diabetic mice suggest that glucagon and insulin may be mediators of the feeding response. Adrenalectomy enhanced the feeding induction, but dexamethasone administration had no effect. Thus, postprandial changes in insulin and glucagon may link chaperone gene expression to feeding, possibly in several tissues including liver. 相似文献
58.
Edward T. Crosby Stephen H. Halpern Stephen H. Rolbin 《Journal canadien d'anesthésie》1989,36(6):701-704
The safety of epidural anaesthesia in patients with active, recurrent genital herpes simplex (HSV) infections is controversial. We reviewed the six-year experience of the use of epidural anaesthesia in this patient population in two institutions. Eighty-nine parturients with active genital HSV were administered epidural anaesthesia for Caesarean section. No patient suffered an adverse outcome related to either the anaesthetic or the virus. The theoretical risks of regional anaesthesia in the parturient with active herpes genitalis are reviewed. We conclude from available data that the risk of an adverse outcome is small and does not contraindicate the use of epidural anaesthesia in patients with recurrent infection. 相似文献
59.
Michael C. Dalsing MD Melissa Kevorkian BS Beth Raper BA Craig Nixon MS Stephen G. Lalka MD Dolores F. Cikrit MD Joseph L. Unthank PhD Malcolm B. Herring MD 《Annals of vascular surgery》1989,3(2):127-133
This study evaluates the potential for endothelial seeding of a collagen-impregnated Dacron graft with or without surface modifiers (fibronectin, heparin) to attach and retain these cells during flow. Human umbilical endothelial cells were harvested, cultured, labeled with Indium111-oxine and seeded onto 30 mm X 4 mm diameter grafts. Six graft surfaces were studied: 1) a collagen-impregnated Dacron graft, HemashieldR (C); 2) C + fibronectin (C + F); 3) C + heparin (C + H); 4) C + F + H; 5) HytrelR + F (Hyt + F); and 6) Hyt + F + H. Radioactive loss determined the percentage attachment and then percentage retention of labeled inoculum after a one-hour in vitro perfusion. Scanning electron and light microscopy demonstrated the endothelium on the graft surface following perfusion. Fibronectin-coated grafts had a significantly higher percentage attachment than those without fibronectin (ANOVA, P less than 0.05). However, the percentage retention following perfusion was similar for all Dacron grafts and statistically inferior to the HytrelR grafts studied (ANOVA, P less than 0.05). SEM evaluation of the C + F + H graft surface was qualitatively the most impressive Dacron surface for seeding, yet was inferior to the HytrelR graft. We conclude that fibronectin benefits the initial attachment of endothelium to collagen-coated Dacron rivaling the HytrelR surface. Fibronectin does not improve percentage retention of the HemashieldR surface during perfusion, therefore, some of its initial benefit is lost. 相似文献
60.
Hung-Tao Hsu Stephen J. Ryan 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》1986,224(1):1-6
In one eye each of four cynomolgus monkeys, an 8-mm penetrating injury was made through the equator; there was retinal perforation with vitreous loss. None of the four eyes with this injury developed posterior vitreous detachment or retinal detachment during a follow-up period of 8 months to 1 year.Another group of 26 monkeys had the same injury but also had 0.5 ml autologous whole blood injected into the vitreous at the time of injury. The eyes were examined weekly and enucleated at scheduled intervals from 1 day to 52 weeks post-injury. Posterior vitreous detachment occurred at the earliest at 2 weeks post-injury, and was ultimately present in 91% of the eyes. Vitreous detachment can occur either as a separation at the level of the internal limiting membrane or as a cleavage within the cortical vitreous. Retinal detachment occurred at the earliest at 8 weeks post-injury, and eventually was present in 50% of the eyes. The retinal detachment was tractional; no retinal breaks were detected in any of the eyes.This study was supported by grants EY02061 and EY03040 from the National Institutes of HealthPresented at the 1984 meeting of the Club Jules Gonin in Lausanne, Switzerland 相似文献