全文获取类型
收费全文 | 264593篇 |
免费 | 25699篇 |
国内免费 | 18849篇 |
专业分类
耳鼻咽喉 | 2290篇 |
儿科学 | 2869篇 |
妇产科学 | 3485篇 |
基础医学 | 31088篇 |
口腔科学 | 4543篇 |
临床医学 | 36665篇 |
内科学 | 38853篇 |
皮肤病学 | 2542篇 |
神经病学 | 14393篇 |
特种医学 | 9772篇 |
外国民族医学 | 162篇 |
外科学 | 25751篇 |
综合类 | 44898篇 |
现状与发展 | 70篇 |
一般理论 | 21篇 |
预防医学 | 16916篇 |
眼科学 | 7800篇 |
药学 | 27998篇 |
254篇 | |
中国医学 | 15967篇 |
肿瘤学 | 22804篇 |
出版年
2024年 | 912篇 |
2023年 | 4352篇 |
2022年 | 11144篇 |
2021年 | 13960篇 |
2020年 | 10525篇 |
2019年 | 9040篇 |
2018年 | 9553篇 |
2017年 | 8729篇 |
2016年 | 8097篇 |
2015年 | 12491篇 |
2014年 | 15164篇 |
2013年 | 13195篇 |
2012年 | 19674篇 |
2011年 | 21756篇 |
2010年 | 13262篇 |
2009年 | 10582篇 |
2008年 | 13788篇 |
2007年 | 13541篇 |
2006年 | 13565篇 |
2005年 | 13380篇 |
2004年 | 8522篇 |
2003年 | 8061篇 |
2002年 | 6729篇 |
2001年 | 5998篇 |
2000年 | 6302篇 |
1999年 | 6579篇 |
1998年 | 4038篇 |
1997年 | 3986篇 |
1996年 | 3213篇 |
1995年 | 3007篇 |
1994年 | 2443篇 |
1993年 | 1563篇 |
1992年 | 2124篇 |
1991年 | 1798篇 |
1990年 | 1446篇 |
1989年 | 1210篇 |
1988年 | 1153篇 |
1987年 | 988篇 |
1986年 | 798篇 |
1985年 | 592篇 |
1984年 | 365篇 |
1983年 | 268篇 |
1982年 | 166篇 |
1981年 | 158篇 |
1980年 | 117篇 |
1979年 | 156篇 |
1978年 | 58篇 |
1977年 | 55篇 |
1975年 | 60篇 |
1974年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
银耳制剂对小鼠移植性肿瘤预防及其机理的实验研究 总被引:4,自引:0,他引:4
小鼠在移植肿瘤细胞前,注射银耳制剂,显示出银耳对荷腹水型或荷实体瘤小鼠肿瘤的生长有明显的抑制作用.正常小鼠给银耳制剂后,其腹腔巨噬细胞(M¢)数量与功能、形态有明显变化,此M¢可吞噬和杀伤肿瘤细胞. 相似文献
992.
The localization of tachykinin-immunoreactivity in the cat visual cortex (area 17) was investigated using immunohistochemical methods. Strong laminar specificity was observed, with immunoreactivity highest in layer V, followed by layers I, VI, II and III, and the lowest density in layer IV. Most of the immunoreactive product was localized in neuronal processes. A few immunopositive cell bodies were also present. The immunopositive neurons were non-pyramidal, multipolar, or bipolar in shape, and mostly found in layer V. There were particularly dense immunopositive fibers and varicosities around somata in layer V. These may represent tachykinin-containing presynaptic terminals (boutons). The results provide anatomical evidence that tachykinin may primarily affect layer V neurons in the cat visual cortex. 相似文献
993.
F W Symington B E Symington P Y Liu H Viguet U Santhanam P B Sehgal 《Transplantation》1992,54(3):457-462
The potential involvement of cytokines in acute graft-versus-host disease led us to analyze interleukin-6 in serial serum sets from 22 allogeneic marrow recipients who developed either grade 3 or 4 GVHD (n = 10), grade 2 GVHD (n = 6), or grade 1 or no diagnosed GVHD (n = 6). A total of 279 serial serum samples taken three times weekly before day 35 were analyzed. Maximum IL-6 levels were greater than 40 U/ml (range, 40-1536 U/ml), 11-40 U/ml, and less than or equal to 10 U/ml for six, eleven, and five patients, respectively. Serum IL-6 peaks were temporally related to onset of GVHD, onset of a syndrome of hepatorenal dysfunction (HRD), or bilateral lung infiltration. Eight of ten patients who developed grade 3 or 4 GVHD overall had IL-6 maxima of greater than 10 U/ml an average of 1.5 +/- 1.8 days before the clinical onset. Fifteen of 17 patients with peak IL-6 levels greater than 10 U/ml developed symptoms of hepatic and renal dysfunction within three days of the peak, while none of five patients with less than or equal to 10 U/ml of Il-6 developed HRD. Regression analysis demonstrated a linkage between the log magnitudes of the serum IL-6 peaks and onset of either GVHD or HRD within three days (P = 0.001). Furthermore, IL-6 peaks tended to precede GVHD onset for the 10 patients whose GVHD onset and IL-6 peak were within three days of each other (P = 0.02). These results, confirmed by both specific bioassay and by IL-6 ELISA, support the idea that acute GVHD in humans involves a cytokine cascade that includes production of IL-6 in addition to the previously reported involvement of tumor necrosis factor alpha and interferon-gamma. 相似文献
994.
995.
人胎儿雪旺氏细胞的体外培养及其纯化研究 总被引:3,自引:1,他引:2
本实验用酶消化法从孕14~19周人胎儿周围神经中分离培养雪旺氏细胞,结合差速贴壁和阿糖胞苷处理进行纯化,根据S-100蛋白免疫细胞化学染色和形态学特征,分析不同时期雪旺氏细胞的纯化程度。实验结果显示:培养4d,倒置相差显微镜下观察,雪旺氏细胞呈典型的双极或三极形,端对端或旋涡状排列,S-100蛋白免疫细胞化学染色呈阳性反应,其比例约占98%;在2~3周内,雪旺氏细胞的纯度维持在85%~90%;培养35d,雪旺氏细胞约占80%;单纯采用阿糖胞苷或差速贴壁处理,培养35d,雪旺氏细胞约占70%;原代培养92d,传代11代细胞生长良好。实验结果表明,多种方法联合使用较单一方法所得的纯度高。本方法快速、简便,能为雪旺氏细胞作为移植材料提供足够的来源。 相似文献
996.
Hyperoxaluria is frequently seen in patients with inflammatory bowel disease, or after resection of the ileum. It is assumed to be responsible for the development of nephrolithiasis, nephrocalcinosis (oxalate nephrosis) and progressive renal impairment in these patients. Steatorrhea may aggravate the severity of hyperoxaluria. A 60-year-old male underwent massive resection of the jejunum and ileum 10 years prior to admission, due to strangulation of the small bowel, with occlusion of the superior mesenteric artery. He remained well except for steatorrhea which developed two-and-a-half years prior to admission, when microhematuria, proteinuria and oxaluria developed progressively. Since that time, the nephrolithiasis, nephrocalcinosis and renal failure have continued to worsen despite therapy with oxalate restriction and oxalate-binding agents. A renal biopsy, performed late in the clinical course, showed severe changes in the renal parenchyma. The decline in renal function proved irreversible. The unusual metabolic consequences of massive resection of the small intestine and their mechanisms are discussed. 相似文献
997.
The purpose of this experiment is to study the role of arginine vasopressin (AVP) in acute cerebral ischemic edema in Mongolian gerbils. The results show that intracerebroventricular injection (ICV) of AVP exacerbates acute ischemic brain edema, while ICV of AVP antiserum significantly decreases the ischemic brain edema. Nimodipine (calcium antagonist) cannot block this role of AVP in brain edema. In addition, the cortical Na(+)-K+ ATPase activity is significantly decreased, while the cAMP content of ischemic cortex and hypothalamus and the cGMP content of the hypothalamus are markedly increased after AVP ICV. These suggest that AVP may play an important role in the pathophysiologic process of ischemic brain edema by inhibiting the Na(+)-K+ ATPase activity of the cerebral cell membrane and the AVP receptors mediated by cAMP and cGMP.
相似文献
998.
999.
1000.
测定110例肝病的抗凝血酶Ⅲ(AT-Ⅲ)活性,62例低于正常(56.4%),均值为60.1±38.2%。50例正常对照为100.0±26.7%。重症肝炎、慢性活动性肝炎及失代偿期肝硬化活性显著下降,均值分别为12.9±13.0%、51.0±34.6%、43.3±29.6%.AT-Ⅲ活性在评价肝脏功能方面较凝血酶原时间敏感,具有一定的实用意义。 相似文献