全文获取类型
收费全文 | 39261篇 |
免费 | 2643篇 |
国内免费 | 2287篇 |
专业分类
耳鼻咽喉 | 285篇 |
儿科学 | 912篇 |
妇产科学 | 511篇 |
基础医学 | 5095篇 |
口腔科学 | 878篇 |
临床医学 | 3939篇 |
内科学 | 7025篇 |
皮肤病学 | 1227篇 |
神经病学 | 1512篇 |
特种医学 | 922篇 |
外国民族医学 | 6篇 |
外科学 | 2434篇 |
综合类 | 6645篇 |
现状与发展 | 3篇 |
预防医学 | 2141篇 |
眼科学 | 403篇 |
药学 | 6780篇 |
13篇 | |
中国医学 | 1723篇 |
肿瘤学 | 1737篇 |
出版年
2024年 | 110篇 |
2023年 | 566篇 |
2022年 | 1368篇 |
2021年 | 1597篇 |
2020年 | 1471篇 |
2019年 | 1130篇 |
2018年 | 1110篇 |
2017年 | 1204篇 |
2016年 | 1165篇 |
2015年 | 1211篇 |
2014年 | 2472篇 |
2013年 | 2212篇 |
2012年 | 2180篇 |
2011年 | 2562篇 |
2010年 | 2086篇 |
2009年 | 1864篇 |
2008年 | 2017篇 |
2007年 | 2103篇 |
2006年 | 1782篇 |
2005年 | 1769篇 |
2004年 | 1401篇 |
2003年 | 1329篇 |
2002年 | 1139篇 |
2001年 | 1018篇 |
2000年 | 950篇 |
1999年 | 854篇 |
1998年 | 810篇 |
1997年 | 739篇 |
1996年 | 577篇 |
1995年 | 610篇 |
1994年 | 524篇 |
1993年 | 388篇 |
1992年 | 358篇 |
1991年 | 242篇 |
1990年 | 172篇 |
1989年 | 120篇 |
1988年 | 113篇 |
1987年 | 107篇 |
1986年 | 83篇 |
1985年 | 106篇 |
1984年 | 109篇 |
1983年 | 85篇 |
1982年 | 83篇 |
1981年 | 69篇 |
1980年 | 51篇 |
1979年 | 42篇 |
1978年 | 23篇 |
1977年 | 35篇 |
1976年 | 34篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Non-ionic contrast media (CM) are proven to be significantly safer than the high osmolar ionic contrast media (HOCM). Nevertheless deaths are reported after administration of non-ionic agents. The aim of the study was to investigate the rate of adverse reactions to non-ionic CM with special regard to high-risk patients and the effects of premedication with H1-and H2-receptor antagonists.In a prospective study conducted over about 2 years 12 995 examinations with intravenous or intra-arterial non-ionic CM were evaluated. Premedication with H1-and H2-antagonists was used in 1276 high-risk patients with known adverse reaction to CM, history of allergy or severe cardiac or pulmonary disease. 229 patients received no premedication inspite of known risk factors. In total, there were 143 (1.10%) adverse reactions (mild in 0.58%, moderate in 0.41% and severe in 0.05%). In high-risk patients there were adverse reactions in 4.37% without and in 1.57% with premedication. There were no severe adverse reactions in the high-risk patients after premedication. The age of the patient, CM dosage and CM concentration were not shown to be risk factors in the present study. In conclusion, the additional premedication with H1- and H2-antagonists could be an effective agent to reduce the risk of mild and moderate adverse reactions and to avoid severe adverse reactions in high-risk patients.
Correspondence to: U. Fink 相似文献
82.
83.
P. Andersson K. LeBlanc B-. Eriksson J. Samuelsson 《European journal of haematology》1997,59(5):310-317
Abstract: Polycythaemia vera (PV) is a myeloproliferative disorder characterized by haematopoietic progenitor cells being hypersensitive to cytokines such as erythropoietin, interleukin-3, stem cell factor and insulin-like growth factor 1, which results in an increased production of mature blood cells. The pathogenetic cellular mechanism(s) behind this hypersensitivity to cytokines is unknown, but the number of cytokine receptors and the interaction between ligand and receptor are normal in PV. Interest has therefore focused on post-receptor mechanism(s). Haematopoietic cell phosphatase (HCP) is an intracellular tyrosine phosphatase that has been demonstrated to regulate proliferative signals negatively induced by the cytokines mentioned above. Moreover, motheaten mice that genetically lack HCP have an increased amount of erythroid progenitors that are hypersensitive to Epo, and patients with familial polycythaemia have been shown to exhibit a mutation of the Epo receptor gene that includes the docking site for HCP. We therefore studied mRNA expression of HCP in pure populations of CD34+ cells, granulocytes, platelets and lymphocytes from patients with PV, chronic myeloid leukaemia (CML) or essential thrombocythemia (ET), as well as healthy controls. Using a polymerase chain reaction analysis employing specific primers for HCP, we failed to detect any abnormalities of HCP expression in PV in any of the cell populations that were examined. Moreover, HCP mRNA expression was similar in ET and CML compared to controls. Finally, Western blot analysis revealed a normal HCP protein content in PV granulocytes and platelets. We therefore conclude that neither an impaired expression of the HCP gene nor a defect in HCP protein synthesis is present in PV, and does not seem to play a role in the aetiology of this disorder. 相似文献
84.
D. Schiffer M.T. Giordana P. Cavalla M.C. Vigliani A. Attanasio 《International journal of developmental neuroscience》1993,11(2)
The astrocytic reaction in the rat after brain injury has been studied immunohistochemically for intermediate filaments (GFAP and vimentin), also with double staining procedures, and for markers of proliferation (BrdU and PCNA). GFAP-positive reactive astrocytes appeared around the lesion, where they were vimentin-positive and at a distance. BrdU and PCNA showed a high labelling index around the wound at day 2 and scattered positive nuclei were also found at a distance in the ipsilateral side. BrdU-positive astrocytes represented a minor fraction of GFAP- and vimentin-positive astrocytes. The expression of vimentin persisted at least 15 days after the lesion. Our results could suggest that distant reactive astrocytes originate through hypertrophy while those close to lesion arise by hyperplasia from mature or immature glial cells. The hypothesis is formulated that cells of the periventricular matrix contribute to the post-traumatic proliferative activity. 相似文献
85.
以聚合酶链反应(PCR)法在mRNA水平检测T淋巴细胞受体α链可变区基因表达为例,介绍用~(32)P标记的人工合成寡核苷酸探针对PCR产物特异性作阳性证实的方法。该法以干琼脂糖凝胶作为支持物、相对较为简便和省财。用Ca探针以干凝胶作支持物的杂交结果,证实29个Vα基因的PCR扩增中物均为特异性的,放射自显影的带型与位置和溴乙锭染色所示完全吻合。 相似文献
86.
87.
88.
89.
90.
目的 探讨脊麻药中复合微量芬太尼对牵拉反应的防治效果。方法 选择美国麻醉医师协会(american society of anesthesiologists,AsA)Ⅰ-Ⅱ级、足月、初产及单胎而需行剖宫产术的病人60例,随机分成2组,每组30例。2组病人的年龄、性剐、体重、局麻药用量、麻醉方法均无显著性差异,均选用腰硬联合麻醉(combined spinal—epidural anesthesia,CSEA)。A组:等比重0.5%罗哌卡因9-11mg+芬太尼10μg。B组:等比重0.5%罗哌卡因9-11mg。观察术中牵拉反应和生命体征并记录,进行统计学处理。结果 2组间麻醉前、后相对应的MAP(平均动脉压)、HR(心率)、RR(呼吸频率)和SpO2(血氧饱和度)变化均无显著性差异(JP〉0.05),2组间新生儿Apgar评分均无显著性差异(P〉0.05),比较2组术中的牵拉反应,A组明显优于B组,有显著性差异(P〈0.05)结论 脊麻药中加入微量芬太尼对牵拉反应有良好的防治效果。 相似文献