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   30529篇
  免费   3397篇
  国内免费   2229篇
耳鼻咽喉   293篇
儿科学   348篇
妇产科学   289篇
基础医学   2775篇
口腔科学   804篇
临床医学   3843篇
内科学   3874篇
皮肤病学   277篇
神经病学   1302篇
特种医学   1074篇
外国民族医学   9篇
外科学   2732篇
综合类   6504篇
现状与发展   12篇
一般理论   6篇
预防医学   2630篇
眼科学   646篇
药学   3812篇
  56篇
中国医学   2836篇
肿瘤学   2033篇
  2024年   205篇
  2023年   627篇
  2022年   1690篇
  2021年   2106篇
  2020年   1615篇
  2019年   1129篇
  2018年   1148篇
  2017年   1206篇
  2016年   1058篇
  2015年   1542篇
  2014年   1902篇
  2013年   1984篇
  2012年   2680篇
  2011年   2890篇
  2010年   2040篇
  2009年   1667篇
  2008年   1796篇
  2007年   1709篇
  2006年   1477篇
  2005年   1227篇
  2004年   938篇
  2003年   819篇
  2002年   746篇
  2001年   479篇
  2000年   324篇
  1999年   268篇
  1998年   170篇
  1997年   126篇
  1996年   88篇
  1995年   98篇
  1994年   96篇
  1993年   68篇
  1992年   46篇
  1991年   34篇
  1990年   36篇
  1989年   19篇
  1988年   20篇
  1987年   21篇
  1986年   16篇
  1985年   18篇
  1984年   9篇
  1983年   3篇
  1982年   4篇
  1981年   7篇
  1979年   2篇
  1976年   1篇
  1970年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Germplasm cryopreservation and expansion of gonocytes/prospermatogonia or spermatogonial stem cells (SSCs) are important; however, it's difficult in cattle. Since inhibitors of Mek1/2 and Gsk3β (2i) can enhance pluripotency maintenance, effects of 2i-based medium on the cultivation of bovine prospermatogonia from the cryopreserved tissues were examined. The testicular tissues of newborn bulls were well cryopreserved. High mRNA levels of prospermatogonium/SSC markers (PLZF, GFRα-1) and pluripotency markers (Oct4/Pouf5, Sox2, Nanog) were detected and the PLZF+/GFRα-1+ prospermatogonia were consistently identified immunohistochemically in the seminiferous cords. Using differential plating and Percoll-based centrifugation, 41.59% prospermatogonia were enriched and they proliferated robustly in 2i medium. The 2i medium boosted mRNA abundances of Pouf5, Sox2, Nanog, GFRα-1, PLZF, anti-apoptosis gene Bcl2, LIF receptor gene LIFR and enhanced PLZF protein expression, but suppressed mRNA expressions of spermatogonial differentiation marker c-kit and pro-apoptotic gene Bax, in the cultured prospermatogonia. It also alleviated H2O2-induced apoptosis of the enriched cells and decreased histone H3 lysine (K9) trimethylation (H3K9me3) and its methylase Suv39h1/2 mRNA level in the cultured seminiferous cords. Overall, 2i medium improves the cultivation of bovine prospermatogonia isolated from the cryopreserved testes, by inhibiting Suv39h1/2-mediated H3K9me3 through Mek1/2 and Gsk3β signalling, evidencing successful cryopreservation and expansion of bovine germplasm.  相似文献   
32.
In peritoneal dialysis (PD), a cloudy dialysate is an alarming finding. Bacterial peritonitis is the most common cause, however, atypical infections and non‐infectious causes must be considered. A 46‐year‐old man presented with asthenia, paraesthesia, foamy urine and hypertension. Laboratory testing revealed severe azotaemia, anaemia, hyperkalaemia and nephrotic‐range proteinuria. Haemodialysis was started through a central venous catheter. Later, due to patient preference, a Tenckhoff catheter was inserted. Conversion to PD occurred 3 weeks later, during hospitalization for a presumed central line infection. A month later, the patient was hospitalized for neutropenic fever. He was diagnosed an acute parvovirus infection and was discharged under isoniazid for latent tuberculosis. Four months later, the patient presented with fever and a cloudy effluent. Peritoneal fluid (PF) cytology was suggestive of infectious peritonitis, but the symptoms persisted despite antibiotic therapy. Bacterial and mycological cultures were negative. No neoplastic cells were detected. Mycobacterium tuberculosis eventually grew in PF cultures, despite previous negative molecular tests. Directed therapy was then initiated with excellent response. Thus, facing a cloudy effluent, one must consider multiple aetiologies. Diagnosis of peritoneal tuberculosis is hampered by the lack of highly sensitive and specific exams. Here, diagnosis was only possible due to positive mycobacterial cultures.  相似文献   
33.
34.
35.
Yu  Hongjuan  Zeng  Xueyun  Sui  Mingjie  Liu  Rui  Tan  Rachel Lee-Yin  Yang  Jinjin  Huang  Weidong  Luo  Nan 《Quality of life research》2021,30(3):855-866
Quality of Life Research - This study aimed to compare the measurement properties of EQ-5D-3L(3L) and EQ-5D-5L(5L) in patients with acute myeloid leukemia (AML) in China. We consecutively recruited...  相似文献   
36.
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   
37.
38.
临床活体部分小肠移植术移植肠的处理   总被引:12,自引:7,他引:5  
目的 报告我国首例活体小肠移植术的移植肠处理体会。方法 为1例18岁男性超短肠综合征患放行了活体部分小肠移植术,供肠来自患的父亲(44岁),切取供体回肠150cm,UW液灌洗血管,将移植肠动、静脉车受体腹主动及及下腔静脉而吻合,移植肠近端与受体空肠近端行端端吻合,远端与受体空肠远端行侧端吻合,末端造口,术后给子抗排斥,抗感染,抗凝及营养支持等治疗。结果 术后管出现贫血,单纯疱疹病感染和急性排斥  相似文献   
39.
目的 分析临床急性感染性疾病所致肝功能损害的特点及其恢复时间。方法 对 135例急性感染性疾病患者入院肝功能指标进行分析 ,观察治疗第 2周及第 4周时患者异常肝功能指标恢复情况。结果 除 6例死亡外 ,其余患者异常肝功能指标升高多在正常值上限 3倍以内 ,治疗第 4周异常肝功能指标治愈率分别为 AL T92 .4%、AST91.6 %、GGT75 .6 %、AL P91.3%、 SB10 0 %、 SB’ 10 0 %和 TBA 85 .7% ,HBs Ag ( )携带者与 HBs Ag (- )者治疗第 4周上述指标治愈率无显著差异。第 4周时 GGT仍升高者恢复缓慢或不易恢复正常。结论 急性感染性疾病致肝功能损害多呈轻度及一过性升高 ;HBs Ag ( )携带者肝脏应急储备及修复功能较正常人无明显下降 ;GGT恢复缓慢或不易恢复正常者可能留有持久性的肝内毛细胆管损伤  相似文献   
40.
应用原生质体融合法选育林可霉素高产菌株   总被引:6,自引:0,他引:6  
将林可霉素产生菌N65—2^#、S78—1^#的原生质体分别热灭活和紫外灭活,并将灭活原生质体用PEG融合,从中获得92-201^#融合株,其摇瓶效价分别较N65—2^#、S78—1^#提高17%、52%,且色素分泌少,传代稳定性强。  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