全文获取类型
收费全文 | 742630篇 |
免费 | 312338篇 |
国内免费 | 65846篇 |
专业分类
耳鼻咽喉 | 6624篇 |
儿科学 | 9599篇 |
妇产科学 | 9904篇 |
基础医学 | 146766篇 |
口腔科学 | 10867篇 |
临床医学 | 126136篇 |
内科学 | 167039篇 |
皮肤病学 | 9746篇 |
神经病学 | 46854篇 |
特种医学 | 26171篇 |
外国民族医学 | 300篇 |
外科学 | 92779篇 |
综合类 | 131875篇 |
现状与发展 | 110篇 |
一般理论 | 82篇 |
预防医学 | 72440篇 |
眼科学 | 28892篇 |
药学 | 107252篇 |
483篇 | |
中国医学 | 70593篇 |
肿瘤学 | 56302篇 |
出版年
2023年 | 9123篇 |
2022年 | 21582篇 |
2021年 | 26853篇 |
2020年 | 23307篇 |
2019年 | 27634篇 |
2018年 | 29214篇 |
2017年 | 28308篇 |
2016年 | 26059篇 |
2015年 | 33056篇 |
2014年 | 38155篇 |
2013年 | 36381篇 |
2012年 | 48464篇 |
2011年 | 54387篇 |
2010年 | 41502篇 |
2009年 | 44131篇 |
2008年 | 38316篇 |
2007年 | 35660篇 |
2006年 | 34941篇 |
2005年 | 35063篇 |
2004年 | 27107篇 |
2003年 | 24706篇 |
2002年 | 22700篇 |
2001年 | 23229篇 |
2000年 | 19518篇 |
1999年 | 25119篇 |
1998年 | 21413篇 |
1997年 | 21279篇 |
1996年 | 20411篇 |
1995年 | 20334篇 |
1994年 | 19225篇 |
1993年 | 16416篇 |
1992年 | 16846篇 |
1991年 | 15432篇 |
1990年 | 13982篇 |
1989年 | 13397篇 |
1988年 | 12551篇 |
1987年 | 11793篇 |
1986年 | 10911篇 |
1985年 | 9734篇 |
1984年 | 7308篇 |
1983年 | 7102篇 |
1982年 | 7910篇 |
1981年 | 7364篇 |
1980年 | 7001篇 |
1979年 | 6917篇 |
1978年 | 5949篇 |
1977年 | 6216篇 |
1976年 | 5834篇 |
1975年 | 5553篇 |
1974年 | 5142篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
83.
Background
HSVtk/ganciclovir (GCV) gene therapy has been extensively studied in tumors and relies largely on the gene expression of HSVtk. Most studies, however, have failed to demonstrate any significant benefit of a controlled gene expression strategy in cancer treatment. The Tet-On system is commonly used to regulate gene expression following Dox induction. We have evaluated the antitumor effect of HSVtk/ganciclovir gene therapy under Tet-On regulation by means of adeno-associated virus-2 (AAV-2)-mediated HSVtk gene transfer with direct intratumoral injections in mice bearing breast cancer tumors. 相似文献84.
85.
大鼠静脉窦高压致硬膜血管变化的研究 总被引:1,自引:1,他引:0
目的探讨大鼠静脉窦高压后硬膜血管变化及其静脉窦高压在硬脑膜动静脉瘘形成中的作用。方法体重200~250g的SD雄性大鼠110只,随机分为静脉窦高压组(85只)和假手术组(25只),将静脉窦高压组85只大鼠闭塞左侧横窦和上矢状窦前1/3,并吻合右侧颈总动脉和颈外静脉,制成静脉窦高压模型。假手术组大鼠单纯解剖相应的颈部血管和硬脑膜窦,但不行吻合或闭塞。术后90d,随机取7只静脉窦高压组大鼠和5只假手术组大鼠,行硬脑膜血管明胶墨汁灌注,观察硬膜血管的状况。结果术后90d静脉窦高压组和假手术组大鼠的硬膜血管数分别为(10.7±1.5)条/mm,(10.3±0.6)条/mm,差异无显著性。在静脉窦高压组中1只大鼠有硬脑膜动静脉瘘,其形态和结构与生理性动静脉短路类似。结论大鼠静脉窦高压一段时间后,颅内硬膜血管无明显增生。颅内硬脑膜动静脉瘘的形成很可能是由动静脉间的短路发展而来。 相似文献
86.
Hirschsprung disease (HSCR) is a congenital disorder characterized by an absence of ganglion cells in the nerve plexuses of the lower digestive tract. Although mutations in eight different genes (EDNRB, EDN3, ECE1, SOX10, RET, GDNF, NTN, SIP1) have been identified in affected individuals, it is now clear that RET and EDNRB are the primary genes implicated in the etiology of HSCR. All eight genes are involved in the early development of the enteric nervous system, and most act through two distinct biochemical pathways mediated by RET and EDNRB. Mutations in RET and EDNRB account for up to 50% and 5% of HSCR cases in the general population, respectively. Interaction between these two signaling pathways could modify RET expression and, therefore, HSCR phenotype. Here, we report the case of a 1-year-old Taiwanese boy who presented with abdominal distension since birth and bilious vomiting after feeding. HSCR (short-segment type) was diagnosed based on X-ray, lower gastrointestinal series and biopsy findings. Mutation analysis revealed a heterozygous T>C missense mutation in exon 1 of the EDNRB gene, that substitutes the highly conserved cysteine-90 residue in the extracellular domain of the G protein-coupled receptor with an arginine residue (C90R). No RET gene mutation was detected in this patient. 相似文献
87.
88.
Abstract: Background: Few studies have examined in depth the labor progression of multiparas to determine if there is any additional impact of being parous beyond the first birth. The objective of this study was to determine the effect of parity on labor progression in contemporary obstetric practice. Methods: Our sample consisted of all low‐risk women who delivered a term, live‐born infant from January 2002 to March 2004 at a single institution in Delaware, United States (n = 5,589). The median duration of labor by each centimeter of cervical dilation was computed for parity = 0 (n = 2,645); parity = 1 (n = 1,839); parity = 2 (n = 750); and parity = 3 + (n = 355). Results: Multiparas had a significantly faster labor progression from 4 to 10 cm (293, 300, and 313 min, respectively, for parity = 1, parity = 2, and parity = 3 +), compared with nulliparas (383 min for parity = 0), as well as a shorter second stage of labor. However, no significant differences were found in duration of the active phase or the second stage of labor among multiparas. Conclusions: Additional childbearing appears to have no effect of on the progression of labor among multiparous subgroups. The difference in duration of the active phase between nulliparas and multiparas is substantially smaller in a contemporary population. (BIRTH 33:1 March 2006) 相似文献
89.
Legionella pneumophila is a common cause of sporadic community-acquired pneumonia, but culture-proven legionellosis is rarely diagnosed. There is no laboratory test for Legionnaires' disease that can detect all patients with the disease. Culture is the standard diagnostic method and should be initiated as soon as possible in suspected cases. We describe a rare case of community-acquired pneumonia caused by L. pneumophila serogroup 6. A 77-year-old man was admitted to a tertiary care hospital because of high fever, productive cough, and progressive dyspnea. Chest radiography showed bilateral pneumonia, which led to respiratory failure necessitating mechanical ventilatory support. Despite antibiotic therapy, his condition continued to deteriorate and acute renal failure also developed. Urine was negative for L. pneumophila. Culture of the sputum yielded L. pneumophila serogroup 6, although there was no elevation of the serum antibody titer. Pneumonia resolved gradually and he was extubated after treatment with levofloxacin followed by erythromycin. L. pneumophila other than serogroup 1 should be included in the differential diagnosis of patients with suspected atypical community-acquired pneumonia. 相似文献
90.