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   25807篇
  免费   2432篇
  国内免费   2123篇
耳鼻咽喉   210篇
儿科学   264篇
妇产科学   365篇
基础医学   3229篇
口腔科学   506篇
临床医学   3498篇
内科学   3959篇
皮肤病学   196篇
神经病学   1500篇
特种医学   975篇
外国民族医学   14篇
外科学   2716篇
综合类   4124篇
现状与发展   8篇
一般理论   4篇
预防医学   1615篇
眼科学   604篇
药学   2809篇
  15篇
中国医学   1528篇
肿瘤学   2223篇
  2024年   95篇
  2023年   412篇
  2022年   1076篇
  2021年   1360篇
  2020年   1003篇
  2019年   911篇
  2018年   876篇
  2017年   874篇
  2016年   760篇
  2015年   1171篇
  2014年   1547篇
  2013年   1277篇
  2012年   1882篇
  2011年   1962篇
  2010年   1303篇
  2009年   992篇
  2008年   1414篇
  2007年   1348篇
  2006年   1285篇
  2005年   1398篇
  2004年   936篇
  2003年   919篇
  2002年   733篇
  2001年   589篇
  2000年   645篇
  1999年   655篇
  1998年   428篇
  1997年   382篇
  1996年   324篇
  1995年   312篇
  1994年   275篇
  1993年   181篇
  1992年   204篇
  1991年   171篇
  1990年   138篇
  1989年   99篇
  1988年   103篇
  1987年   76篇
  1986年   77篇
  1985年   52篇
  1984年   34篇
  1983年   27篇
  1982年   12篇
  1981年   9篇
  1980年   8篇
  1979年   10篇
  1978年   3篇
  1977年   4篇
  1975年   2篇
  1929年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
BackgroundRadical/cytoreductive nephrectomy or nephron-sparing surgery may be thought to be not safe or unfeasible in some renal cell carcinoma (RCC) patients in which tumor is locally advanced or highly complicated. Neoadjuvant therapy may reduce the volume of the tumor, thus facilitates surgery. The aim the study is to evaluate the efficacy and safety of neoadjuvant combination of pazopanib or axitinib and PD-1-activated dendritic cell-cytokine-induced killer (PD-1/DC-CIK) cell immunotherapy in those patients.MethodsData from 16 RCC patients who received neoadjuvant pazopanib (Group P, n=9) or axitinib (Group A, n=7) plus PD-1/DC-CIK cells immunotherapy were reviewed retrospectively. A total of 9 participants that were potential candidates for radical/cytoreductive nephrectomy (RN/CN) had locally advanced tumor and 5 participants with partial nephrectomy (PN) absolute indications had highly complicated tumors. The efficacy outcomes were based on volume changes of the primary tumor, lymph nodes, and tumor thrombus in 13 participants with complete computed tomography (CT) imaging. The treatment-related toxicities and surgical complications were also reported.ResultsWith a median of 2.1 months treatment, the overall volume of the tumors decreased by a median of 42.30% [interquartile range (IQR): 19.37–66.78%]. Specifically, the median reduction of tumor volume was 88.77 and 15.50 cm3 in group P and group A, respectively (P=0.014). However, participants in Group P were more likely to experience grade 3 or 4 treatment-related adverse events (AEs) than those in Group A (44.4% vs. 0). Finally, all participants were candidates for appropriate surgery after neoadjuvant therapy (as assessed by the surgeon), and 10 participants accepted surgery, including 5 PN, 4 RN/CN, and 1 lymph node dissection. A solitary participant had Clavien grade IV acute renal failure required dialysis and another had grade II lymphatic leakage.ConclusionsNeoadjuvant combination of pazopanib or axitinib and PD-1/DC-CIK cells immunotherapy was well-tolerated and could effectively reduce the volume of tumors in locally advanced or highly complicated RCC patients.  相似文献   
92.

Plastic pollution control has been on top of the political agenda in China. In January 2020, China announced a phased ban on the production and usage of various types of single-use plastics as a solution to environmental pollution problems. However, the outbreak of COVID-19 seems to be a new obstacle to the ban on single-use plastic products. To basically satisfied the daily necessities and contain the spread of SARS-CoV-2 under the background of the regular epidemic prevention and control in China, online ordering, contactless delivery and wearing mask have become an important and feasible way of daily life. However, the unrestrained use of disposable plastic bags, lunch boxes and masks within the nationwide quarantine leads to hundreds of millions of plastics wastes every day. The potential environmental pollution caused by the use of disposable plastic products during the pandemic should arouse social concern. The Chinese government should manage environmental protection in parallel with anti-pandemic endeavors as the situation of the pandemic evolves.

  相似文献   
93.
94.
步枪立姿射击稳定性的力学特征   总被引:2,自引:0,他引:2  
射击运动技术是衡量运动员水平的关键,它对运动员姿态控制的稳定性有相当高的要求。本文以步枪立姿运动为例,分析其姿态控制的力学特征,运用运动稳定性原理,求得人体上躯干最佳姿态控制角,并论证了人体躯干长度,前臂长度对稳定性的影响。最后将理论结果与对一些国内外著名运动员实测参数比较分析,证明了理论结论与实际基本相符。  相似文献   
95.
RNA silencing: a conserved antiviral immunity of plants and animals   总被引:19,自引:0,他引:19  
Ding SW  Li H  Lu R  Li F  Li WX 《Virus research》2004,102(1):109-115
RNA silencing is a novel RNA-guided gene regulatory mechanism operational in a wide range of eukaryotic organisms from fission yeast, plants, to mammals. This article reviews the recent progress on aspects of RNA silencing that are related to its biological function as a conserved antiviral immunity of plants and animals, and highlights features of this novel antiviral response in invertebrate animals as compared to the known innate and adaptive immunities. Finally, we discuss evidence that suggests a natural antiviral role for RNA silencing in vertebrates as well as experimental approaches that may facilitate the identification of first mammalian viral suppressors of RNA silencing.  相似文献   
96.
Children with chromosome 22q11.2 deletion syndrome commonly are found to have morphological brain changes, cognitive impairments, and elevated rates of psychopathology. One of the most commonly and consistently reported brain changes is reduced cerebellar volume. Here, we demonstrate that, in addition to the global cerebellum reductions previously reported, volumetric reductions of the anterior lobule and the vermal region of the neo-cerebellum in the mid-sagittal plane best differentiate children with the deletion from typically developing children. These results suggest that the morphological changes of specific portions of the cerebellum may be an important underlying substrate of cognitive impairments and increased incidence of psychopathology in this group.  相似文献   
97.
牛磺酸对大鼠心脏模拟缺血再灌注损伤的保护作用   总被引:2,自引:0,他引:2  
在离体大鼠心脏模拟缺血再灌注(I/R)损伤的模型上观察了牛磺酸的心肌保护作用。实验结果发现预先给大鼠牛磺酸灌胃(300mg/kg)三日或再灌注同时给药(20mmol/L),对心肌均有保护作用,明显减少心肌细胞内的Mb、LDH的漏出,降低心肌MDA的生成,减轻细胞内钙的聚集,促进心肌ATP含量的恢复。在本实验条件下预防应用牛磺酸较再灌注的同时应用更为有效,表现为更大程度地减少LDH漏出,抑制心肌MDA生成和钙聚集。结果证明牛磺酸具有心肌保护作用,对于防治心肌I/R损伤可能具有临床应用价值。  相似文献   
98.
本研究采用霍乱弧菌古典生物型569B菌株及EI-Tor生物型菌株,以Westphal的热酚-水法及高速离心等方法提取LPS,血凝法测其效价,并比较不同菌株的LPS刺激小鼠腹腔巨噬细胞产生TNF的情况。实验表明569B菌株LPS血凝效价较高,诱导小鼠腹腔巨噬细胞产生TNF的能力较强。  相似文献   
99.
本文用流槽系统,定量地研究年龄对健康人红细胞与培养的人脐静脉内皮细胞粘附的影响。在本研究所选用的两个年龄阶段,其结果显示:①红细胞自身特性的改变对粘附的数目没有明显的影响,但随着年龄的增加粘附的强度增大;②在自体血浆存在时,随着年龄的增加红细胞与内皮细胞的粘附增强。这可能与心脑血管病如心肌梗塞、脑血栓形成等多发生在40岁以上的中老年人有关。  相似文献   
100.
应用扫描电镜观察体外LAK细胞与直肠腺癌细胞相互作用时的形态学变化。结果表明:LAK细胞与HR8348细胞均具有主动互相趋向运动,效靶细胞借其细胞突起及微绒毛相互接触。LAK细胞及肿瘤细胞的细胞突起及微绒毛由早期的平面接触逐渐发展为犬牙交错状结合。效靶细胞紧密结合后,靶细胞鼓泡,细胞膜出现环形穿孔。互相接触,结合的微绒毛及细胞突起在靶细胞的溶解过程中起到一个物理微桥的作用。LAK细胞分泌的杀伤物质通过微桥介导靶细胞的溶解。效靶细胞互相结合的微绒毛间形成关闭小室,它可能与维持局部杀伤物质浓度有关。  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