全文获取类型
收费全文 | 102445篇 |
免费 | 10847篇 |
国内免费 | 6310篇 |
专业分类
耳鼻咽喉 | 852篇 |
儿科学 | 1906篇 |
妇产科学 | 1177篇 |
基础医学 | 8896篇 |
口腔科学 | 1664篇 |
临床医学 | 14299篇 |
内科学 | 12331篇 |
皮肤病学 | 1037篇 |
神经病学 | 3831篇 |
特种医学 | 3165篇 |
外国民族医学 | 22篇 |
外科学 | 7180篇 |
综合类 | 22862篇 |
现状与发展 | 26篇 |
一般理论 | 7篇 |
预防医学 | 10357篇 |
眼科学 | 2367篇 |
药学 | 12249篇 |
171篇 | |
中国医学 | 8472篇 |
肿瘤学 | 6731篇 |
出版年
2024年 | 459篇 |
2023年 | 1518篇 |
2022年 | 3793篇 |
2021年 | 4880篇 |
2020年 | 3992篇 |
2019年 | 3063篇 |
2018年 | 3093篇 |
2017年 | 3384篇 |
2016年 | 3036篇 |
2015年 | 4555篇 |
2014年 | 5775篇 |
2013年 | 6312篇 |
2012年 | 8837篇 |
2011年 | 9288篇 |
2010年 | 7127篇 |
2009年 | 6095篇 |
2008年 | 6742篇 |
2007年 | 6671篇 |
2006年 | 6030篇 |
2005年 | 5041篇 |
2004年 | 3870篇 |
2003年 | 3706篇 |
2002年 | 3079篇 |
2001年 | 2361篇 |
2000年 | 1718篇 |
1999年 | 1217篇 |
1998年 | 610篇 |
1997年 | 642篇 |
1996年 | 499篇 |
1995年 | 403篇 |
1994年 | 383篇 |
1993年 | 236篇 |
1992年 | 183篇 |
1991年 | 173篇 |
1990年 | 152篇 |
1989年 | 121篇 |
1988年 | 114篇 |
1987年 | 98篇 |
1986年 | 73篇 |
1985年 | 60篇 |
1984年 | 35篇 |
1983年 | 19篇 |
1982年 | 16篇 |
1981年 | 22篇 |
1980年 | 13篇 |
1979年 | 17篇 |
1977年 | 12篇 |
1974年 | 11篇 |
1973年 | 8篇 |
1971年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Luan Shu Zi- Chun Hua 《中国药理通讯》2006,23(3):30-30
Triptolide is potent immunosuppressive has been reported to inhibit autoimmunity, compound isolated from Chinese herbal medicine. Triptolide allograft attributed to the suppression of T cells via NF - kB rejection and GVHD, and its efficacy was previously pathway and apoptosis. In the present study, we detailedly analyzed Triptolide' s function on murine primary T cell. We found that Triptolide could inhibit T cell activation and proliferation by dramatically down - regulating cell division and cell cycle. Triptolide inhibited T cell activation in a dose- dependent manner, and the inhibition was mediated by both NF- kB pathway and AP - 1 pathway. 相似文献
13.
Kenji Tsukada Shigeru Kobayashi Tatsuya Gotoh Naoki Asakage Masayuki Sekine Morio Sasaki Eiji Miyazaki Takahisa Suzuki Toshio Yamada Shu Hirai Shigetaka Yamazaki 《Digestive endoscopy》2006,18(1):55-58
A case of early gastric carcinoma accompanied by Dieulafoy ulcer is presented. The patient, a 26‐year‐old female, visited our emergency room with chief complaints of massive hematemesis and tarry stool. The initial endoscopic examination revealed a superficial depressed lesion with a faded color accompanied by a tiny ulcer with converging folds at the anterior wall of the middle gastric body. Although no active bleeding vessel was found at that time, the patient was admitted to our hospital for further check‐ups and treatment. On the 6th hospital day, she developed massive hematemesis resulting in shock. Urgent endoscopy, this time, disclosed an exposed bleeding vessel at the small ulcer floor previously mentioned, and endoscopic hemostasis was achieved. Since, however, a biopsy at initial examination from the surrounding depressed area proved carcinoma, a partial distal gastrectomy was subsequently carried out. Histological examination of the resected specimen confirmed the diagnosis of carcinoma limited to the mucosa and submucosa along with findings consistent with Dieulafoy ulcer. This is a rare case of combination of early cancer and Dieulafoy ulcer particularly in such a young patient. A review of the literature is also presented. 相似文献
14.
寻找有效的抗原表位是近期肿瘤免疫治疗的热点.人端粒酶逆转录酶(hTERT)的免疫学特性使其成为肿瘤免疫治疗中一个吸引人的目标。从人和鼠系统获得的数据证实,细胞毒淋巴细胞(CTL)能识别hTERT特异的肽并杀死多种组织类型hTERT表达的肿瘤细胞。由于hTERT在人肿瘤组织中的广泛表达,在极少正常组织的低水平表达,临床试验已开始检验将hTERT作为肿瘤免疫治疗目标的可行程度。近期树突状细胞(DC)转运系统及其相关技术的发展和成熟提供了一个快速有效筛选抗原肽的方法。 相似文献
15.
The effect associated with the substitution of adenine (A) for guanidine (G) in the promoter region of the apolipoprotein AI gene (?75 bp) with plasma apo AI and high-density lipoprotein (HDL) levels was investigated in the European Atherosclerosis Research Study (EARS). This is a study of healthy offspring (cases) of fathers who had suffered premature myocardial infarction (MI) before age 55 years (n = 565) and age- and sex-matched controls (n = 1,078) from 12 European countries, divided into 5 regions based on geography and language. The frequency of the polymorphism was not significantly different among the regions and the relative frequency of the rare A allele was similar in cases and controls (0.159 vs. 0.142) combining data from all regions. Individuals with one or more A allele had significantly higher plasma apo AI levels (P < 0.05) than individuals homozygous for the G allele. This effect was consistent in all regions. The data were analyzed separately in males and females. In females, those with one or more A allele had significantly higher apo AI levels (P = 0.05) than individuals homozygous for the G allele, and this raising effect of the A allele was greater in cases than controls for both apo AI (5.23% vs. 1.56%) and HDL (4.48% vs. 1.89%). In males, the A allele was associated with higher levels of apo AI and HDL, but the effect was much smaller and the differences did not reach statistical significance. In the females, where the effect of the A allele was strongest, the effect on apo AI associated with genotype was evident in non-smokers, and individuals with one or two A alleles had 3.6% higher apo AI and 3.14% higher HDL levels than individuals homozygous for the G allele. However, in the female smokers the raising effect of the A allele was greatly reduced (0.56%). Thus genetic variation in the promoter region of the apo AI gene is associated with differences in apo AI and HDL levels in healthy individuals throughout Europe, but the effect is modulated by gender, environmental factors such as smoking, and a family history of MI. 相似文献
16.
Using the polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) analysis, we have examined the highly conserved regions of the p53 gene in 58 biopsy samples of head and neck tumors. Mutations were found in 13/58 (23%) tumor specimens, but not in 6 normal tissues. Ten of 13 mutations were due to single base changes and the remaining 3 were 1- or 8-base deletion mutants. These mutations were clustered in exons 5 and 7 and resulted in amino acid changes. Our results seem to indicate that mutations in the p53 gene contribute to a significant number of cases of the head and neck tumors including 20% of nasopharyngeal carcinoma biopsies. The relationship of Epstein-Barr virus or human papillomavirus and p53 gene mutations in this group of cancers was also analyzed and discussed. 相似文献
17.
目的 分析国产光敏剂血卟啉单甲醚(HMME)在不同溶液中光漂白反应动力学规律,加深对光漂白反应复杂反应过程的理解,并为HMME-PDT治疗微血管病变的数学建模研究提供实验依据和参数。
方法 根据光化学反应动力学原理,从理论上推导出在单纯溶液和复杂溶液(含可被光氧化的底物)中,单态氧介导的光漂白反应动力学方程,通过对实验测定的漂白数据(不同时间点的HMME浓度)进行拟合,进一步验证理论推导出光漂白反应动力学方程。
结果 HMME在单一溶液体系(PBS、DMSO)中的光漂白符合1级反应动力学过程,在含底物的复杂体系(白蛋白缓冲液、细胞悬液)中符合2级反应动力学过程。
结论 HMME在不同溶液体系中的光漂白遵循不同的反应动力学规律。根据化学反应动力学原理进行光漂白等复杂光化学反应过程的数学模拟是可行的,并有利于对复杂光化学反应过程的深入理解。 相似文献
18.
19.
葡萄籽多酚对多药耐药的逆转作用及其机制 总被引:2,自引:0,他引:2
目的:探讨葡萄籽多酚(GSPs)逆转多药耐药的作用及其对多药耐药相关蛋白GSTπ、TopoⅡ α表达的影响。方法:以人乳腺癌MCF-7细胞及其耐药株MCF-7/ADR细胞作为实验对象,用MTT法观察GSPs对多药耐药的逆转作用,免疫细胞化学技术观察GSPs对GSTπ、TopoⅡα等多药耐药相关蛋白表达的影响。结果:GSPs在1.2、2.4mg/L浓度时对细胞无毒性作用,并且均能逆转MCF-7/ADR细胞的多药耐药性,逆转倍数分别为5.77和9.79倍;GSPs可使MCF-7/ADR细胞GSh表达下降,但对TopoⅡ α表达无影响。结论:体外试验证实GSPs具有多药耐药逆转作用,其机制可能与降低肿瘤细胞内GSTπ的表达有关,提示GSPs是一种潜在的肿瘤化疗增敏剂。 相似文献
20.
Objective: To explore the expression level and its clinical significance of hypoxia inducible factor
1α (HIF-1α) in non-small lung cancer. Methods: The expression of HIF-1α was detected in 68 human
non-small lung cancer samples by immunohistochemistry. Results: (1) Thirty-nine (57.35%) out of the 68
human non-small lung cancer samples was positive for HIF-1α; (2) The positive rate of HIF-1α in adenocarcinoma
and squamous carcinoma was 54.76% (23/42) and 61.54% (16/26) respectively. No significant
difference was found between adenocarcinoma and squamous carcinoma of non-small lung cancer in the
expression of HIF-1α (P>0.05). The positive rate of HIF-1α in middle-high differentiation was 74.28%
(26/35), significantly higher than in low differentiation (39.39%, 13/33) (P<0.05); (3) The positive expression
of HIF-1α was not correlated to the sexes, ages, tumor stage and lymph node status. Conclusion:
The expression of HIF-1α is higher in non-small lung cancer and is correlated to differentiation. 相似文献