首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   90466篇
  免费   8326篇
  国内免费   6620篇
耳鼻咽喉   749篇
儿科学   938篇
妇产科学   1064篇
基础医学   11029篇
口腔科学   1679篇
临床医学   12303篇
内科学   13532篇
皮肤病学   855篇
神经病学   4902篇
特种医学   3329篇
外国民族医学   61篇
外科学   8884篇
综合类   15502篇
现状与发展   33篇
一般理论   3篇
预防医学   5394篇
眼科学   2602篇
药学   9416篇
  75篇
中国医学   4976篇
肿瘤学   8086篇
  2024年   335篇
  2023年   1703篇
  2022年   3997篇
  2021年   4856篇
  2020年   3669篇
  2019年   3163篇
  2018年   3211篇
  2017年   2989篇
  2016年   2704篇
  2015年   4282篇
  2014年   5109篇
  2013年   4329篇
  2012年   6525篇
  2011年   7309篇
  2010年   4399篇
  2009年   3375篇
  2008年   4327篇
  2007年   4624篇
  2006年   4525篇
  2005年   4634篇
  2004年   2855篇
  2003年   2614篇
  2002年   2295篇
  2001年   1946篇
  2000年   2176篇
  1999年   2532篇
  1998年   1681篇
  1997年   1607篇
  1996年   1221篇
  1995年   1070篇
  1994年   891篇
  1993年   608篇
  1992年   717篇
  1991年   610篇
  1990年   555篇
  1989年   476篇
  1988年   392篇
  1987年   349篇
  1986年   247篇
  1985年   191篇
  1984年   92篇
  1983年   76篇
  1982年   41篇
  1981年   45篇
  1980年   29篇
  1979年   30篇
  1965年   1篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
Summary From 1987 to 1990 the authors treated 20 cases of spondylolisthesis by an improved operative procedure including excision of the medial part of the superior articular processes of the slipped vertebra, excision of the soft tissue between the ununited isthmi, and excision of the ligamentum flavum between the intervertebral space above the slipped segment. In some instances the lower portion of the lamina over the slipped vertebra should be resected. A U-shaped rod was used to hold sublaminar fixation of two segments above and below the slipped vertebra, with the slipped vertebra spared. Utilizing the U-shaped rod as support, bone strips were placed along the lateral and anterior sides of the rod to bridge the gap between the laminae of the displaced vertebra. Other bone grafts were focused on the facet joints. The patients were allowed ambulation early postoperatively. 19 cases could be evaluated at preliminary follow-up. All showed satisfactory results.  相似文献   
53.
X B Zhou 《中华外科杂志》1990,28(1):52-5, 63
In order to evaluate the operation of the adrenal autotransplantation into omentum with arterio-venous anastomosis, the right adrenal of fifteen dogs was preliminarily removed and then the left adrenal vein was diverted into the portal circulation by micro surgical technique. Before and after the diversion, the serum cortisol taken from portal vein, hepatic vein, inferior vena cava and peripheral vein was analysed by radioimmunoassay. The dog's adrenal cortex, pituitary were removed for light and electron-microscopic examination. The experimental results demonstrate that the cortisol inactivation effect of the liver was not statistically different before and after the procedure (P greater than 0.05). Thus, we believe that the omentum which has obvious absorbability and revascularity is a reasonable site for adrenal transplantation. And we also found the adrenal cortex left appear slight hypotrophy and pituitary hypertrophy after the diversion. The cause however, requires further research.  相似文献   
54.
The effects of hypercapnia and hypoxia on two local cerebral blood flows in the parietal cortex (PC-BF) and rostral ventrolateral medulla (RVLM-BF) were examined using laser Doppler flowmetry in anesthetized rats. Hypercapnia for 45 s duration at the end-tidal CO2 between 5% and 10%, induced by increasing inspiratory CO2, increased both cerebral blood flows and systemic blood pressure in a degree-dependent manner. The response of RVLM-BF was significantly stronger than that of PC-BF. Both cerebral blood flow responses to hypercapnia were not influenced by cutting peripheral chemoreceptor afferent nerves. Hypoxia for 45 s duration at the end-tidal O2 between 12% and 6%, induced by decreasing inspiratory O2, produced an increase of similar magnitude in both RVLM and PC local blood flows in a degree-dependent manner and a decrease in systemic blood pressure. The responses of both PC-BF and RVLM-BF to hypoxia were significantly diminished after cutting peripheral chemoreceptor afferent nerves. It is concluded that: (1) the RVLM-BF is much more sensitive to hypercapnia than the PC-BF; and (2) activation of peripheral arterial chemoreceptors possibly contributes to hypoxia-induced increase in the RVLM-BF and PC-BF.  相似文献   
55.
56.
Ten multiparous lactating sows were used to investigate whether intramammary infusion of lipopolysaccharides (LPS; Escherichia coli 0111:B4; 2.0 μg/kg of body weight) would affect the circulating concentrations of Ca, P, 25‐hydroxyvitamin D (25‐OHD), tumour necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6) and cortisol. The sows were randomly allotted to either control group (control) or LPS‐treated group with five individuals per group and were infused with either physiological saline solution or LPS solution. The rectal temperature and udder quarter appearance were recorded at 0 (just before infusion), 1, 3, 7, 12 or 24 h after infusion. Blood samples were taken at 0, 1, 3, 7, 12 or 24 h after infusion. Before infusion, the rectal temperatures of all sows were below 39.2°C. At 3 and 7 h after infusion, the sows in the LPS group had a rectal temperature over 39.4°C. At 24 h after infusion, the rectal temperatures returned to pre‐infusion levels. Serum Ca and P concentrations in the LPS group decreased (P < 0.05) after LPS infusion compared with the control group at 1 h after infusion. No significant differences (P > 0.05) in the concentrations of 25‐OHD were observed between groups control and LPS at any sampling time. Increased (P < 0.01) concentrations of serum TNF‐α, IL‐6 and cortisol were observed in the LPS group compared with the control group at 3 and 7 h after infusion respectively. In conclusion, the elevation of serum concentrations of TNF‐α, IL‐6 and cortisol and the alterations of circulating concentrations of Ca and P following LPS infusion indicate that the immune system has been activated and immune activation may affect macromineral homeostatic regulation, which might have important implications for metabolic health of lactating sows. Lowered serum Ca and P following immune activation also shows a causative mechanism whereby immune activation increases the risk of secondary disorders such as mastitis‐metritis‐agalactia syndrome. However, immune activation did not affect circulating concentrations of vitamin D metabolites.  相似文献   
57.
帕金森病立体定向手术并发脑内出血的原因分析   总被引:2,自引:0,他引:2  
目的:探讨帕金森病立体定向手术颅内出血并发症原因及对策。方法:自1999年4月至2003年3月我们对药物治疗效果不理想的510例帕金森病病人行立体定向毁损手术,术后出现颅内出血9例,其中毁损灶出血3例,穿刺道出血6例。结果:手术治疗4例.保守治疗5例。术后意识恢复但遗留偏瘫4例,经非手术治疗5例.恢复良好,未遗留明显功能障碍。全组无死亡病例。结论:采用磁共振结合微电极导向提高靶点定位精确度,减少微电极记录针道数,降低毁损温度,重视围手术期处理等措施,有助于降低颅内出血并发症的危险。  相似文献   
58.
Polystyrene-bound metal [2,9 or 2,10 (or 2,16 or 2,17) bis(3,4-dicarboxybenzoyl)]phthalocyaninates were synthesized by Friedel-Crafts reaction of polystyrene with the corresponding metal phthalocyaninates. Co(II) and Cu(II) [2,9 or 2,10 (or 2,16 or 2,17) bis(3,4-dicarboxybenzoyl)]-phthalocyaninate (PS-CodaPc and PS-CudaPc) contained 0,13 mmol · g?1 (12,4 wt.-%) and 0,13 mmol · g?1 (12,8 wt.-%) of CodaPc and CudaPc, respectively. They were soluble in N,N'-dimethylformamide, but only partially soluble in chloroform, tetrahydrofuran (THF), dimethyl sulfoxide, N-methyl-2-pyrrolidone, and pyridine. The THF extracts contained 0,12 mmol · g?1 (11,4 wt.-%) and 0,18 mmol ? g?1 (17,2 wt.-%) of PS-CodaPc and PS-CudaPc, respectively. The thermal stability of the polymers was studied using thermogravimetric and differential thermal analysis in nitrogen and synthetic air atmosphere. The contents of MdaPc(M: metal) in THF-extracted polymers calculated from the data of residue in thermogravimetric analysis are 0,12 mmol · g?1 for PS-CodaPc and 0,19 mmol · g?1 for PS-CudaPc. In addition, the sensitive properties of the polymers towards toxic gases were also investigated by quartz microbalance transducers. The results show that the quartz microbalance sensors coated with both polymers were sensitive to NO2 and chlorinated hydrocarbons, i.e. chloroform and perchloroethylene. The sensitivity to NO2 was 6,53 · 10?7 m3 · mL?1 · s?1 for PS-CodaPc and 1,90 · 10?6 m3 · mL?1 · s?1 for PS-CudaPc, and that to chloroform and perchloroethylene was 2,33 · 10?8 and 4,60 · 10?8 m3 · mL?1 · s?1, respectively, for PS-CodaPc and 4,79 · 10?8 and 9,51 · 10?7 m3 · mL?1 · s?1 for PS-CudaPc.  相似文献   
59.
本文采用1:3病例对照研究方法,对甾体避孕药的使用与血栓栓塞性疾病(急性心肌梗塞、脑栓塞、脑血栓形成和深静脉血栓形成)间的关联进行多因素分析。结果提示在我国广泛应用的甾体避孕药(主要为国产Ⅰ号避孕药)并不增加血栓栓塞性疾病的危险性。用药和停药时间的长短与血栓栓塞性疾病的发生无关,并与高血压病之间亦不存在协同作用。  相似文献   
60.
电视硬质气管镜治疗大气道良性肿瘤   总被引:4,自引:4,他引:0  
目的探讨电视硬质气管镜在大气道良性肿瘤治疗中的价值.方法2002年9月~2005年4月,我院应用电视硬质气管镜治疗大气道良性肿瘤7例,其中气管1例,隆突1例,左主支气管3例,右主支气管2例.手术采用静脉全身麻醉,喷射通气供氧,探查评估气道后,首先冷冻或电凝肿瘤,破坏肿瘤血供,再以活检钳分块取出,蒂部采用冷冻或氩气凝固处理;对于宽蒂肿瘤,内镜下将肿瘤主体清除后中转开胸行气管局部切除吻合术.结果7例手术均顺利,无一例死亡和严重并发症发生.6例气管窄蒂良性肿瘤镜下完整摘除,1例气管膜部宽蒂平滑肌瘤先内镜清除肿瘤主体后中转开胸行气管局部切除.术后病理为错构瘤2例,平滑肌瘤3例,嗜酸性肉芽肿性腺瘤1例,炎症组织1例.7例随访3~36个月,平均17.3月,无肿瘤复发.结论电视硬质气管镜治疗大气道良性肿瘤安全可靠.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号