全文获取类型
收费全文 | 58681篇 |
免费 | 4091篇 |
国内免费 | 1584篇 |
专业分类
耳鼻咽喉 | 509篇 |
儿科学 | 2031篇 |
妇产科学 | 1997篇 |
基础医学 | 5772篇 |
口腔科学 | 1344篇 |
临床医学 | 8709篇 |
内科学 | 7101篇 |
皮肤病学 | 677篇 |
神经病学 | 3060篇 |
特种医学 | 2457篇 |
外国民族医学 | 20篇 |
外科学 | 4345篇 |
综合类 | 12179篇 |
现状与发展 | 11篇 |
一般理论 | 2篇 |
预防医学 | 4333篇 |
眼科学 | 1114篇 |
药学 | 3004篇 |
85篇 | |
中国医学 | 1425篇 |
肿瘤学 | 4181篇 |
出版年
2024年 | 146篇 |
2023年 | 873篇 |
2022年 | 1734篇 |
2021年 | 2398篇 |
2020年 | 2532篇 |
2019年 | 1851篇 |
2018年 | 1843篇 |
2017年 | 1836篇 |
2016年 | 2255篇 |
2015年 | 1987篇 |
2014年 | 3968篇 |
2013年 | 3995篇 |
2012年 | 3455篇 |
2011年 | 3696篇 |
2010年 | 2950篇 |
2009年 | 2837篇 |
2008年 | 2749篇 |
2007年 | 2911篇 |
2006年 | 2729篇 |
2005年 | 2323篇 |
2004年 | 2059篇 |
2003年 | 1797篇 |
2002年 | 1484篇 |
2001年 | 1341篇 |
2000年 | 1029篇 |
1999年 | 879篇 |
1998年 | 736篇 |
1997年 | 710篇 |
1996年 | 661篇 |
1995年 | 574篇 |
1994年 | 518篇 |
1993年 | 461篇 |
1992年 | 379篇 |
1991年 | 363篇 |
1990年 | 318篇 |
1989年 | 266篇 |
1988年 | 302篇 |
1987年 | 246篇 |
1986年 | 189篇 |
1985年 | 200篇 |
1984年 | 129篇 |
1983年 | 89篇 |
1982年 | 99篇 |
1981年 | 81篇 |
1980年 | 87篇 |
1979年 | 85篇 |
1978年 | 53篇 |
1977年 | 30篇 |
1976年 | 34篇 |
1975年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
目的 探讨儿童颈椎间盘钙化症的影像表现及诊断价值,并提高对本病的认识。方法 回顾分析16例儿童颈椎钙化性椎间盘病的影像表现。结果 16例患均行颈椎平片检查,5例行CT扫描并作了三维重建,8例行MRI检查。16例平片均显示了椎间盘钙化灶,均为单发,CT平扫加三维重建显示4例钙化呈卵圆形,1例钙化为不规则形。MRI检查不仅显示了椎间盘内改变还清晰显示了病变相邻椎体边缘信号改变,在T1、T2加权像上呈低信号。结论 平片检查可以显示椎间盘钙化;CT平扫加三维重建能清晰显示了钙化灶的大小、形态;MRI检查在显示受累椎体及周围组织的改变方面明显优于CT和平片。 相似文献
92.
【目的】探讨端粒酶作为脑膜瘤标志物 ,在肿瘤良恶性鉴别、恶性程度评估以及预后预测等方面的意义。【方法】利用TRAP ELISA方法定量检测 6 1例 (份 )肿瘤标本端粒酶的活性 (以ΔA =A4 50 -A690 表示 ) ,结合肿瘤的分类和患者的临床资料 ,分析端粒酶活性作为肿瘤良恶性及判断预后的标记物的可行性。另取正常脑组织标本 2 0例作为对照。【结果】 30例脑膜瘤中 ,2 9例脑膜瘤均未测到端粒酶活性 ;1例端粒酶阳性 (阳性率 3 3%) ,ΔA =0 2 37;全组ΔA平均值 =0 0 49。 15例恶性脑膜瘤中 14例呈端粒酶阳性 (93%) ,ΔA =1 2 37~ 2 5 16 ;1例端粒酶阴性 ,ΔA =0 0 76 ,全组ΔA平均值 =1 6 30。 16例复发性脑膜瘤端粒酶均阳性 (10 0 %) ,ΔA =1 0 34~ 1 4 78,平均 1 2 5 5。脑膜瘤和复发性脑膜瘤、脑膜瘤和恶性脑膜瘤的端粒酶的阳性率和酶活性表达强度方面差异明显 (P分别为 <0 0 0 1、<0 0 1和 <0 0 0 0 5、<0 0 1)。 2 0例正常脑组织中未检测到端粒酶活性。【结论】端粒酶活性的激活在恶性脑膜瘤和复发性脑膜瘤中是较常见的现象。端粒酶作为肿瘤标志物 ,在脑膜瘤的良恶性鉴别、恶性程度评估、预后预测等方面具有重要的意义。 相似文献
93.
94.
95.
96.
本文报告用间接免疫荧光法检测特异性IgG抗体对流行性出血热的诊断意义。53例不同病期的出血热患者的血清,其间接荧光抗体的阳性率为49/53(占92.45%)。有77.36%的患者血清,检出IgG抗体的时间是在发病后的1~2周。血清中IgG的滴度与疾病的严重性无密切相关。另25例非EHF患者,其血清特异性IgG抗体均为阴性。可见检测特异性IgG抗体对EHF的诊断颇为有用。 相似文献
97.
M. M. Clark † 《Journal of child psychology and psychiatry, and allied disciplines》1987,28(3):417-425
Changing issues in the field of preschool education will be discussed, set in the context of two of my studies which have been concerned with children with special needs in 'ordinary' preschool education, one 'pre-Warnock' in Scotland, and the other 'post-Warnock' in the West Midlands. The concept of special needs will then be widened to include children for whom English is a second language, and also gifted children. Finally, the discussion is extended to early education rather than preschool education with a discussion of the dangers of treating preschool education in isolation. 相似文献
98.
Lin Bo Wang Jian Guo Shen Li Feng Dong Chao Yang Xu Wen Jun Chen Shu Duo Xie Xiang Yang Song Ning Dai Xiao Ming Yuan 《Journal of gastrointestinal surgery》2008,12(8):1359-1363
We previously reported that lymphatic mapping using isosulfan blue can be used to identify sentinel nodes (SNs). This study
was undertaken to evaluate the feasibility of using the SN technique in treating early gastric cancer and to explore its usefulness
for minimal invasive surgery. Twenty-three patients with early gastric cancer who underwent SN biopsy were retrospectively
evaluated. Based on SN evaluation, individualized surgery was performed in five patients with T1N0M0 gastric cancer. When
pathological examination of frozen sections revealed metastasis in SNs, we performed a standard D2 gastrectomy. Laparoscopic
local resection was applied when the SN biopsy was negative. Our results showed that the success rate with SN biopsy in early
gastric cancer was 100%, as were the accuracy, sensitivity, and specificity. All five patients with early gastric cancer had
SNs negative for metastases both by frozen section and by postoperative pathology. Thus, all these patients underwent laparoscopic
local resection without extended lymphadenectomy. We conclude that SN biopsy is a useful tool to individualize the operative
procedure, and laparoscopic local resection can be safely performed using SN guidance in selected patients with early gastric
cancer. 相似文献
99.
Objective: To study the diagnostic value of T2^*-weighted first-pass perfusion imaging in breast tumors. Methods: We analyzed the magnetic resonance imaging (MRI) information along with the pathological and immunohistochemistry results. Magnetic resonance imaging was performed in 28 patients with breast tumor. The time to signal intensity curves were generated according to the T2^*-weighted first-pass perfusion imaging. The curve's maximal signal intensity drop rate and maximal signal intensity decrease time were analyzed and compared with the pathological diagnoses after surgery. Results: Malignant breast lesions showed higher maximal signal intensity drop rate (44.69% ± 17.07 vs. 17.22% ±7.49, P 〈 0.001) than benign lesions, but there was no significant difference of maximal signal decrease time between those two lesions (23.94 s ± 4.92 vs. 20.02 s ± 6.83, P 〉 0.05). Conclusion: The T2^*-weighted first-pass perfusion imaging has enough sensitivity and specificity in breast tumor diagnosis. 相似文献
100.
While much time has been spent deliberating about the definition of play, little emphasis has been placed on what children themselves perceive as play. The aim of the present study was to examine social context as a cue for children's perceptions of play and learning. Ninety-two children aged between four and six years (mean four years nine months) participated in the study and completed the Activity Apperception Story Procedure. Children were asked to sort photographic stimuli into those they believed depicted play/not play and learning/not learning. Each of the stimuli were identified by independent raters as containing one of the following social cues; teacher absence (solitary activity, parallel activity or cooperative activity) or teacher presence (teacher involved activity or teacher directed activity). Findings revealed that children associated teacher absence with play. More specifically, children made links between play and the presence of peers (parallel and cooperative activity). Findings are discussed in relation to play in the early years curriculum, differences in children's early educational experiences and the importance of understanding children's perceptions of play. 相似文献