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   103664篇
  免费   10209篇
  国内免费   4969篇
耳鼻咽喉   2118篇
儿科学   641篇
妇产科学   1875篇
基础医学   11192篇
口腔科学   3386篇
临床医学   7591篇
内科学   12134篇
皮肤病学   1997篇
神经病学   409篇
特种医学   4304篇
外国民族医学   131篇
外科学   19763篇
综合类   17867篇
现状与发展   23篇
预防医学   2142篇
眼科学   393篇
药学   5294篇
  21篇
中国医学   1328篇
肿瘤学   26233篇
  2024年   152篇
  2023年   1432篇
  2022年   2253篇
  2021年   4078篇
  2020年   3574篇
  2019年   3402篇
  2018年   3221篇
  2017年   3664篇
  2016年   4022篇
  2015年   4664篇
  2014年   6960篇
  2013年   6189篇
  2012年   6172篇
  2011年   6840篇
  2010年   5507篇
  2009年   5439篇
  2008年   5557篇
  2007年   5767篇
  2006年   5495篇
  2005年   4892篇
  2004年   3937篇
  2003年   3474篇
  2002年   2950篇
  2001年   2776篇
  2000年   2320篇
  1999年   1867篇
  1998年   1688篇
  1997年   1523篇
  1996年   1329篇
  1995年   1132篇
  1994年   1056篇
  1993年   724篇
  1992年   655篇
  1991年   556篇
  1990年   494篇
  1989年   426篇
  1988年   405篇
  1987年   337篇
  1986年   269篇
  1985年   298篇
  1984年   252篇
  1983年   182篇
  1982年   201篇
  1981年   162篇
  1980年   159篇
  1979年   130篇
  1978年   98篇
  1977年   61篇
  1976年   53篇
  1975年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Aspirate from an argyrophil carcinoma ("carcinoid") of the breast showed malignant dispersed epithelial cells. With Diff-Quik, the cytoplasm was seen to be abundant, with prominent eosinophilic granularity. The nuclei were fairly uniform, round or oval, and eccentric and had a finely stippled chromatin pattern. On histology, the tumor appeared typical for argyrophil carcinoma, and staining with Grimelius for argyrophilic granules was positive. Membrane-bound neurosecretory granules were seen on electron microscopy.  相似文献   
992.
The discharge characteristics of sacral visceral afferents supplying the urinary bladder, urethra, colon and anus to mechanical stimuli were analyzed in the anaesthetized cat. The stimuli used were passive distension (urinary bladder, colon), isovolumetric contraction (urinary bladder), movements of the urethral catheter and mechanical shearing stimuli (mucosal skin of the anal canal). (1) In total 245 afferent units which projected in the pelvic nerve were isolated from the sacral dorsal roots. From one of the following organs, urinary bladder, colon, urethra and anus 117 afferent units were activated. By these stimuli from the bladder, urethra and anus 122 afferent units could not be activated, and as far as tested also not from the colon; in 6 afferent units the classification was unclear. (2) Afferent units from the urinary bladder and the colon responded consistently to passive distension of the respective organ. The units from the urinary bladder showed graded responses at intraluminal pressures of about 10–70 mm Hg and responded also to isovolumetric contractions of the organ. The thresholds of the units from the bladder to passive distension and contraction varied from about 5 to 20 mm Hg intravesical pressure. (3) The afferent units from the urethra and the anus did not react or showed some weak phasic and irregular responses to distension and contraction applied to the urinary bladder or to distension of the colon. They were consistently excited by low threshold mechanical stimulation of the urethra and anus, respectively. (4) The axons from the bladder, urethra and anus were presumably myelinated (conduction velocity above 2 m/s) and conducted at 10.3±6.1 m/s (n=34, mean±SD), 26.3±9.3 m/s (n=13) and 9.5±5.1 m/s (n=37), respectively. The axons from the colon conducted at about 0.5 to 16 m/s (n=20), 13 of them conducting at less than 2 m/s. About 75% of the axons which could not be activated by mechanical stimulation of the visceral organs were presumably unmyelinated (conduction velocity below 2 m/s). (5) Some ongoing activity was found in 9 out of 26 afferent units from the anus but, with one exception, the afferent units from the bladder, urethra and colon were silent. (6) It is concluded that the pelvic afferent units from the urinary bladder, urethra, colon and anus consist of distinct populations with characteristic response patterns. There is no indication from this investigation that the urinary bladder is supplied by sacral afferents which are only recruited at high intravesical pressures during passive distension and isovolumetric contractions and which are possibly associated with pain.Supported by the Deutsche Forschungsgemeinschaft  相似文献   
993.

Background

TONSL has been suggested to function as an oncogene in lung, esophageal and cervical cancer. This study was aimed to identify the expression of TONSL and its role in hepatocellular carcinoma (HCC).

Methods

By data mining in the Cancer Genome Atlas (TCGA) and Human Protein Atlas (HPA) databases, the expression profile of TONSL, its clinical significance, the potential mechanisms of its dysregulation and its underlying biological function in HCC were investigated.

Results

TONSL was significantly upregulated in HCC tissues relative to normal liver tissues (P?<?0.05). High TONSL expression was significantly correlated with advanced TNM stage, poorly differentiated tumors, vascular invasion, elevated serum alpha-fetoprotein expression and a worse prognosis (all P?<?0.05). Multivariate analysis further confirmed that TONSL overexpression was an independent risk factor for poor overall survival (OS) and recurrence-free survival (RFS) in HCC (all P?<?0.05). Additionally, 16% of HCC cases (n?=?370) had TONSL DNA amplification. The total methylation level of TONSL was moderately and negatively correlated with its mRNA expression (P?<?0.05). TONSL was predictively targeted by miR-133b, which was downregulated in HCC and negatively related to TONSL mRNA expression (all P?<?0.05). Kaplan-Meier analyses demonstrated that low miR-133b expression was significantly associated with poor OS and RFS (all P?<?0.05). Moreover, gene set enrichment analysis revealed that cases with TONSL overexpression were enriched in cell cycle regulation pathways (all P?<?0.05).

Conclusions

TONSL holds promise for serving as a prognostic biomarker for HCC. DNA amplification, hypomethylation and miR-133b downregulation could be the mechanisms associated with TONSL upregulation in HCC. TONSL might function as an oncogene via cell cycle regulation pathways in HCC.  相似文献   
994.
《Immunobiology》2022,227(6):152298
PLPPs (Phospholipid phosphatases) are widely expressed in different human tissues, regulate cell signal transduction, and are overexpressed in cancers such as gliomas, pancreatic adenocarcinoma, lung adenocarcinoma, and so on. As a member of the PLPP family, PLPP2 (phospholipid phosphatase 2) plays a vital role in the occurrence and development of breast cancer, but its mechanism is still unclear. Our research found that PLPP2 was overexpressed in breast cancer, and the higher expression level of PLPP2 showed a worse prognosis for breast cancer patients. Further analysis showed that overexpression of PLPP2 affected the expression of CDC34 (cell-division cycle 34), LSM7 (Like-Smith 7), and SGTA (small glutamine-rich tetratricopeptide repeat-containing protein alpha) through EMT (epigenetic-mesenchymal transition) related pathways to promote the occurrence and development of breast cancer. In vitro, silencing PLPP2 significantly reduced the proliferation, invasion, and migration abilities of human breast cancer cells MDA-MB-231. ER+ is a common subtype of breast cancer. Furthermore, we found that the overexpression of PLPP2 was significantly related to the poor prognosis of ER+ breast cancer. These results indicate that PLPP2 has value as a potential therapeutic target for breast cancer, especially for ER+ breast cancer.  相似文献   
995.
低氧促进P19细胞向多巴胺能神经元分化   总被引:1,自引:0,他引:1  
目的观察低氧对P19细胞神经分化的影响,针对其向多巴胺能神经元分化的现象及机制进行探讨。方法实验分为常氧组(20%O2)和低氧组(3%O2,每天低氧10 m in)。对诱导分化的神经元采用免疫细胞化学染色方法鉴定。用流式细胞术及W estern b lot检测多巴胺能神经元,高效液相色谱法测定分泌的多巴胺。用RT-PCR技术检测低氧诱导因子HIF-1αmRNA水平。结果①在分化的P19细胞中,低氧组神经元含量高于常氧组(P<0.05),低氧组多巴胺能神经元含量及所分泌的多巴胺显著高于常氧组(P<0.001);②低氧组诱导期HIF-1αmRNA表达水平明显高于常氧组。结论低氧可以促进P19细胞的神经分化,尤其促进P19细胞向多巴胺能神经元分化,HIF-1α可能在其中起了一定作用。  相似文献   
996.
妇产科手术泌尿系损伤防治方法的探讨   总被引:4,自引:2,他引:4  
目的 探讨妇产科手术泌尿系损伤的特点及防治方法,为临床妇产科手术中防止泌尿系损伤提供参考。方法 对我院妇产科手术中发生的泌尿系损伤的10例临床资料进行回顾性分析。结果 10例患者中输尿管损伤3例,均为术中发现,术中行输尿管端端吻合;膀胱损伤7例,其中5例于术中发现,2例术后形成膀胱阴道瘘,行膀胱修补术,所有病例均痊愈出院。妇产科损伤泌尿系的主要原因有输尿管解剖移位,盆腔粘连严重等。结论 绝大多数妇产科手术中的泌尿生殖系损伤是可以防范的,一旦发生,应及时发现,尽早修补预后良好。  相似文献   
997.
目的为明确Survivin作为膀胱肿瘤患者的肿瘤诊断和监测标志物的可能性,我们检测了Survivin在膀胱肿瘤和非肿瘤患者病变组织的Survivin蛋白及其mRNA表达情况。方法从我科住院病人和膀胱镜检患者中获取31例膀胱癌患者(实验组)和24例非肿瘤患者(对照组)的组织标本,用免疫组织化学法(IHC)和RT-PCR检测Survivin蛋白和基因在肿瘤组织和非肿瘤组织中的表达情况。并对结果行相应的统计学分析。结果IHC检测实验组和对照组Survivin蛋白的阳性率分别为74%(23/31)和4%(1/24),χ2检验P<0.001,IHC的阳性率与肿瘤的分级分期有一定的关系;实验组和对照组RT-PCR检测Survivin mRNA的表达阳性率分别为90%(30/31)和4%(1/24),χ2检验P<0.001。结论膀胱肿瘤组织Survivin蛋白和基因的表达量高于对照组,因此,Survivin有望成为膀胱瘤高危人群筛选,肿瘤诊断和监测的工具之一。  相似文献   
998.
目的构建7q32区域鼻咽癌细胞和组织及原代培养人正常鼻咽上皮细胞的部分基因表达图谱。方法通过差异RT-PCR和Northern杂交的方法检测定位于7q32区域的20个EST在鼻咽癌细胞和鼻咽癌组织及原代培养人正常鼻咽上皮细胞mRNA的表达水平。结果8个EST在鼻咽癌细胞HNE1和原代培养人正常鼻咽上皮细胞中表达量较一致,7个EST在两种细胞中均无表达,3个EST(W72688、H19830、AA130630)在鼻咽癌细胞株中表达上调,而2个EST(AA070437、H90882)在原代培养人鼻咽上皮细胞中表达上调。在13例鼻咽癌活检组织中30.7%(4/13)的AA070437表达下调,77%(10/13)的W72688和77%(10/13)的H19830表达上升。结论构建了7q32区域鼻咽癌细胞和组织及原代培养人正常鼻咽上皮细胞部分基因表达图谱,并初步认为A070437的表达下调和W72688、H19830的过表达与鼻咽癌的发生有关。  相似文献   
999.
Geographic or ethnic differences in the incidence of thyroid carcinoma, as well as in the histologic distribution of thyroid carcinoma between Japan and Western countries, have been described but are still unclear. The recent establishment of histologic criteria for the diagnosis of thyroid carcinoma by the WHO committee has facilitated the comparison of clinicopathological data of patients with thyroid carcinoma all over the world. The aim of the present review article is to clarify the epidemiological and clinicopathological differences of thyroid carcinoma between Japan and Western countries. We found recently no significant differences in the incidence, mortality, and histologic distribution of thyroid carcinoma between Japan and Western countries; this was contrary to our expectation. This is likely attributable to westernization of the Japanese diet, standardized medical levels, and international standardization of histologic criteria of thyroid carcinoma.  相似文献   
1000.
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