全文获取类型
收费全文 | 17602篇 |
免费 | 1426篇 |
国内免费 | 634篇 |
专业分类
耳鼻咽喉 | 66篇 |
儿科学 | 194篇 |
妇产科学 | 166篇 |
基础医学 | 1097篇 |
口腔科学 | 602篇 |
临床医学 | 1606篇 |
内科学 | 3811篇 |
皮肤病学 | 418篇 |
神经病学 | 518篇 |
特种医学 | 673篇 |
外科学 | 1601篇 |
综合类 | 1683篇 |
现状与发展 | 3篇 |
预防医学 | 875篇 |
眼科学 | 171篇 |
药学 | 4502篇 |
5篇 | |
中国医学 | 398篇 |
肿瘤学 | 1273篇 |
出版年
2024年 | 24篇 |
2023年 | 276篇 |
2022年 | 557篇 |
2021年 | 778篇 |
2020年 | 701篇 |
2019年 | 694篇 |
2018年 | 677篇 |
2017年 | 656篇 |
2016年 | 701篇 |
2015年 | 742篇 |
2014年 | 998篇 |
2013年 | 1812篇 |
2012年 | 979篇 |
2011年 | 1027篇 |
2010年 | 814篇 |
2009年 | 758篇 |
2008年 | 770篇 |
2007年 | 762篇 |
2006年 | 644篇 |
2005年 | 640篇 |
2004年 | 531篇 |
2003年 | 485篇 |
2002年 | 410篇 |
2001年 | 344篇 |
2000年 | 276篇 |
1999年 | 224篇 |
1998年 | 198篇 |
1997年 | 237篇 |
1996年 | 151篇 |
1995年 | 161篇 |
1994年 | 137篇 |
1993年 | 149篇 |
1992年 | 125篇 |
1991年 | 121篇 |
1990年 | 104篇 |
1989年 | 97篇 |
1988年 | 94篇 |
1987年 | 104篇 |
1986年 | 76篇 |
1985年 | 94篇 |
1984年 | 89篇 |
1983年 | 66篇 |
1982年 | 61篇 |
1981年 | 54篇 |
1980年 | 47篇 |
1979年 | 41篇 |
1978年 | 42篇 |
1977年 | 29篇 |
1976年 | 33篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
依沙吖啶引产失败后用卡前列甲酯栓的疗效 总被引:2,自引:1,他引:1
目的:观察35例中期妊娠用依沙吖啶1次羊膜腔注射引产失败后,再用卡前列甲酯栓的效果。方法:卡前列甲酯栓1mg,放置于阴道后穹窿,若3h后无宫缩,再放1次。结果:35例孕妇引产成功率100%。引产后24h内阴道流血量200±20mL。出现腹泻,恶心等不良反应各1例。结论:卡前列7甲酯栓用于对依沙吖啶中期引产失败后效果满意。 相似文献
22.
Robert M. Judd Michael K. Atalay Gerald A. Rottman Elias A. Zerhouni 《Magnetic resonance in medicine》1995,33(2):215-223
Interpretation of first-pass myocardial perfusion studies employing bolus administration of T1 magnetic resonance (MR) contrast agents requires an understanding of the relationship between contrast concentration and image pixel intensity. The potential effects of myocardial water exchange rates among the intravascular, interstitial, and cellular compartments on this relationship are controversial. We directly studied these issues in isolated, nonbeating canine interventricular septa. Myocardial T1 was measured three times/s during bolus transit of intravascular (albumin-Gd-DTPA and poly-lysine-Gd-DTPA) and extracellular (gadoteridol) contrast agents. For polylsine-Gd-DTPA, the peak changes in myocardial 1/T1 (ΔR1) scaled nonlinearly with perfusate contrast concentration whereas a linear relationship would be expected for fast water exchange among the vascular, interstitial, and cellular compartments. For all agents, the peak ΔR1 were much smaller than the values expected on the basis of fast myocardial water exchange. The data demonstrate that in isolated myocardial tissue, myocardial T1 enhancement during bolus administration of contrast can be strongly affected by myocardial water exchange for both intravascular and extracellular MR contrast agents. 相似文献
23.
吡那地尔对高血压心脏结构和功能重构的影响 总被引:5,自引:0,他引:5
在等降压剂量下吡那地尔和赖诺普利可使4月龄自发性高血压大鼠的血压下降6.0 ̄8.0kPa,并接近同种属正常血压大刀瓣血压水平。 相似文献
24.
Summary In vivo prostatic secretion was collected from retired breeder Sprague Dawley rats using a method for isolated perfusion of the rat prostatic urethra. Enzymatic acid phosphatase determination was performed on the collected effluent. Control acid phosphatase secretion was 24.2±2.7 nm over 30 minutes. Intravenous phenylephrine 5 mg/kg stimulated a 10 fold increase in acid phosphatase secretion. The secretion seen with phenylephrine was dose dependent and could be blocked with prazosin, but not yohimbine, atropine, or propranolol. Intravenous -adrenergic agonist isoproterenol caused no increase in the secretion of rat prostatic acid phosphatese. Intravenous administration of the cholinergic agonist pilocarpine also resulted in a dose dependent rise in acid phosphatase secretion. The stimulation seen could be blocked by atropine but not phentolamine or propranolol. The stimulation of acid phosphatase secretion seen with 1 adrenergic or cholinergic agonists was not additive. Intravenous vasoactive intestinal peptide did not stimulate acid phosphatase secretion nor did it augment the secretion induced by 1 adrenergic or cholinergic agonists. Release of acid phosphatase into rat prostatic exocrine secretion is under both 1 adrenergic and cholinergic control.Supported by the US Veterans Administration 相似文献
25.
Guerriero S Ajossa S Lai MP Risalvato A Paoletti AM Melis GB 《Human reproduction update》1999,5(5):515-529
This review describes the usefulness of colour Doppler energy (CDE) (or power Doppler) imaging to measure vascularization in the female reproductive tract. CDE imaging is characterized by an increased sensitivity to flow, and thus may be useful in low-flow states and when optimal Doppler angles cannot be obtained. In addition, longer segments of vessels and more individual vessels can be visualized with CDE imaging. The role of CDE imaging in the evaluation of stromal vasculature in normal and in polycystic ovaries is described, and the relationship between follicular vascularity and outcome following in-vitro fertilization are discussed, together with the findings obtained from the evaluation of thecal arteriole of corpus luteum in early pregnancy. The fundamental role of CDE imaging in differentiation among ovarian masses is also reviewed. We summarize the role of CDE imaging in pregnancy, and describe two new applications of three-dimensional power Doppler sonography and the use of ultrasound contrast media. In conclusion, CDE imaging can replace conventional colour Doppler when the information on the direction of flow is not useful. Moreover, the technique appears superior to others for describing microvascular architecture and determining the presence or absence of flow. 相似文献
26.
Regulation of the type I IFN induction: a current view 总被引:14,自引:0,他引:14
The type I IFN-alpha/beta gene family was identified about a quarter of a century ago as a prototype of many cytokine gene families, which led to the subsequent burst of studies on molecular mechanisms underlying cytokine gene expression and signaling. Although originally discovered for their activity to confer an antiviral state on cells, more evidence has recently been emerging regarding IFN-alpha/beta actions on cell growth, differentiation and many immunoregulatory activities, which are of even greater fundamental biological significance. Indeed, much attention has recently been focused on the induction and function of the IFN-alpha/beta system regulated by Toll-like receptors (TLRs), which are critical for linking the innate and adaptive immunities. The understanding of the regulatory mechanisms of IFN-alpha/beta gene induction by TLRs and viruses is an emerging theme, for which much new insight has been gained over the past few years. 相似文献
27.
28.
Previous ultrastructural examination of peripheral blood lymphocytes revealed the presence of intranuclear filamentous structures in multiple sclerosis (MS) and in some optic neuritis (ON) patients. The present investigation was undertaken in the attempt to correlate the presence of such structures with the etiology of ON and MS and possibly to demonstrate the viral origin of the filaments. Suitable virological and serological techniques were used to detect and isolate infectious agents from peripheral blood samples and body excretions of 12 monosymptomatic ON patients at their first acute attack. Nevertheless, any efforts to demonstrate the presence of a virus in these patients have been unsuccessful: no evidence of active viral infection was obtained by serological studies of serum and cerebrospinal fluid samples, nor could viral antigens or inclusions be observed by immunofluorescence and cytochemical analysis. Negative results were also obtained from studies performed in parallel on MS patients and various controls. The significance of the failure to isolate infectious agents from either ON and MS patients is discussed. 相似文献
29.
30.
Minute pieces of rat parotid gland were used in studies of adrenergic regulation of K+ efflux using 86Rb+ as a probe for K+. Noradrenaline induced a concentration-dependent Rb+ efflux, whereas the β1-selective agonist prenalterol was without effect. On the other hand, the β2-selective drug, terbutaline, at high concentrations displayed a small enhancement of Rb+ -secretion. The selective α1-adrenoceptor drug, phenylephrine, was as potent as noradrenaline, whereas the α2-agonist clonidine had only a small effect. The noradrenaline-induced Rb+-efflux was effectively inhibited in the presence of prazosin, an α1-blocker, whereas the α2-antagonist, yohimbine, was roughly 50 times less potent. The results suggest that catecholamine-induced K+-secretion from the rat parotid gland is mediated via activation of post-synaptic α-adrenoceptors of the α1-subtype. 相似文献