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   127032篇
  免费   12587篇
  国内免费   5407篇
耳鼻咽喉   2610篇
儿科学   1012篇
妇产科学   1877篇
基础医学   16541篇
口腔科学   3944篇
临床医学   8539篇
内科学   18066篇
皮肤病学   2501篇
神经病学   5062篇
特种医学   4629篇
外国民族医学   122篇
外科学   18758篇
综合类   18132篇
现状与发展   25篇
预防医学   3059篇
眼科学   582篇
药学   9132篇
  21篇
中国医学   1696篇
肿瘤学   28718篇
  2024年   196篇
  2023年   1637篇
  2022年   4524篇
  2021年   5464篇
  2020年   4101篇
  2019年   4031篇
  2018年   3933篇
  2017年   4424篇
  2016年   4813篇
  2015年   5996篇
  2014年   8121篇
  2013年   7091篇
  2012年   7405篇
  2011年   7975篇
  2010年   6608篇
  2009年   6385篇
  2008年   6813篇
  2007年   6539篇
  2006年   6103篇
  2005年   5529篇
  2004年   4466篇
  2003年   4010篇
  2002年   3367篇
  2001年   3209篇
  2000年   2705篇
  1999年   2325篇
  1998年   2279篇
  1997年   2067篇
  1996年   1761篇
  1995年   1512篇
  1994年   1378篇
  1993年   1100篇
  1992年   907篇
  1991年   788篇
  1990年   679篇
  1989年   572篇
  1988年   559篇
  1987年   503篇
  1986年   520篇
  1985年   511篇
  1984年   420篇
  1983年   329篇
  1982年   331篇
  1981年   298篇
  1980年   244篇
  1979年   170篇
  1978年   112篇
  1977年   79篇
  1976年   65篇
  1975年   28篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Previous studies in the MPTP-lesioned primate model of Parkinson's disease have demonstrated that alpha(2) adrenergic receptor antagonists such as idazoxan, rauwolscine, and yohimbine can alleviate L-dopa-induced dyskinesia and, in the case of idazoxan, enhance the duration of anti-parkinsonian action of L-dopa. Here we describe a novel alpha(2) antagonist, fipamezole (JP-1730), which has high affinity at human alpha(2A) (K(i), 9.2 nM), alpha(2B) (17 nM), and alpha(2C) (55 nM) receptors. In functional assays, the potent antagonist properties of JP-1730 were demonstrated by its ability to reduce adrenaline-induced (35)S-GTPgammaS binding with K(B) values of 8.4 nM, 16 nM, 4.7 nM at human alpha(2A), alpha(2B), and alpha(2C) receptors, respectively. Assessment of the ability of JP-1730 to bind to a range of 30 other binding sites showed that JP-1730 also had moderate affinity at histamine H1 and H3 receptors and the serotonin (5-HT) transporter (IC(50) 100 nM to 1 microM). In the MPTP-lesioned marmoset, JP-1730 (10 mg/kg) significantly reduced L-dopa-induced dyskinesia without compromising the anti-parkinsonian action of L-dopa. The duration of action of the combination of L-dopa and JP-1730 (10 mg/kg) was 66% greater than that of L-dopa alone. These data suggest that JP-1730 is a potent alpha(2) adrenergic receptor antagonist with potential as an anti-dyskinetic agent in the treatment of Parkinson's disease.  相似文献   
142.
未能切除的胰腺癌行区域性导向化疗临床应用报告   总被引:10,自引:0,他引:10  
自1989-1992年间,作者共收治胰腺癌190例,其中有159例未能切除,对其中30例采用了区域性导向化疗,即在手术中经胃网膜石动脉逆行置管至胃十二指肠动脉,术后经该导管注入5-FU等化疗药物,一般每日250mg,共达1-2个月。根据随诊的108例按手术方式分为A组单纯探查24例,B组单纯胆肠转流54例,C组单纯探查加区域性化疗18例,D组胆肠转流加区域性化疗12例。中位期分别为A组3.5个月,  相似文献   
143.
Gd-BOPTA增强MRI对小肝癌的诊断价值   总被引:6,自引:0,他引:6  
目的 比较Gd BOPTA增强MRI与MRI平扫、Gd DTPA动态增强MRI在诊断小肝癌 (SHCC)方面的差异 ,进一步提高小肝癌检出率和诊断准确性并观察其不良反应。资料与方法 手术或穿刺病理证实为SHCC患者 2 5例。采用GESigna 1.5T磁共振扫描仪。行SE序列T1WI、FSE序列T2 WI及Gd DTPA快速动态增强多期扫描。Gd BOPTA增强扫描亦采用静脉团注快速动态增强扫描 (同Gd DTPA) ,并在团注后 15min、6 0min行SE序列T1WI和FMPSPGR序列T1WI扫描各 1次。观察MRI平扫、Gd DTPA快速动态增强和Gd BOPTA增强扫描及延迟扫描对病灶的检出率、包膜显示情况以及病灶的强化特征并行统计学分析。观察其不良反应。结果  2 5例患者共发现病灶4 2个。对SHCC病灶的检出率 ,MRI平扫为 6 9.0 5 % ,Gd DTPA增强为 85 .71% ,Gd BOPTA增强 (动态 延迟 )为95 .2 4 % ,和Gd DTPA增强之间无统计学差异 ,和MRI平扫有统计学意义。病理检查发现 30个病灶有包膜。Gd BOPTA增强对SHCC包膜的显示 ...  相似文献   
144.
经胸小切口在食管癌切除手术中的应用   总被引:3,自引:0,他引:3  
目的探讨经胸小切口治疗食管癌手术的地位和可行性。方法对132例不同分期的食管癌行经胸小切口根治性手术,全部采用颈部吻合。结果切口平均长度13.0±2.0 cm,开关胸时间、开胸时出血量、术后伤口疼痛、呼吸功能受限及患肢活动等方面有显著差异,在手术时间、淋巴结清扫、术中出血及术后胸腔引流和常规手术无差异。结论经胸小切口食管癌根治手术安全、可行,并且有创伤小、恢复快等优点,便于推广应用。  相似文献   
145.
In order to elucidate collagen metabolism in hepatocellular carcinoma (HCC) tissue, we compared levels of different potential markers of collagen metabolism and plasma transforming growth factor-β1 in patients with HCC and in patients with liver cirrhosis. Serum levels of prolyl hydroxylase and the tissue inhibitor of metalloproteinase-1 in patients with HCC were significantly higher than those in patients with liver cirrhosis and increased with the size of the HCC tumour, whereas the serum levels of procollagen type III propeptide and type IV collagen 7S domain were similar in the two groups. In HCC, the increased plasma transforming growth factor-β1 levels were closely correlated with serum levels of prolyl hydroxylase and the tissue inhibitor of metalloproteinase-1. These findings suggest that, in HCC tissue, the intracellular biosynthesis of collagen is enhanced, whereas the secretion of procollagen is disturbed and the degradation of collagen is suppressed by the excess production of the tissue inhibitor of metalloproteinase-1. The results also suggest that plasma transforming growth factor-β1 plays an important role in the altered metabolism of collagen in HCC.  相似文献   
146.
We report a patient with metastatic thyroid carcinoma invading the esophagus in whom barium and MR examinations revealed an expansile intraluminal mass indistinguishable from that of a primary esophageal malignancy. Metastatic thyroid carcinoma should therefore be included in the differential diagnosis of an expansile esophageal mass. As in our patient, MR imaging may be useful for showing that the mass originates in the thyroid gland.  相似文献   
147.
The present paper critically appraises two recent overviews of the literature on rectal cancer and quality of life (QL). These reviews focus on the Anglo-American literature, largely neglect research from other countries, and provide little stimulus regarding future research directions. As an alternative perspective we propose the concept of problem-solving oriented QL research. The major theme is that the QL concept must be integrated into the clinical arena. To begin with, QL researchers must make themselves understandable. We outline several ways in which this can be achieved: (a) placing QL in a broader concept together with outcomes that are more familiar to clinicians; (b) depicting individual patients in the form of QL profiles; (c) clarifying the psychosocial/clinical correlates of particular QL scores of interest; and (d) conducting studies with a definitive practical goal in mind and integrating practitioners and patients into the study group. We illustrate the feasibility of such a research program by performance data from our Marburg-Biedenkopf field trial. Pursuing an ambitious research strategy that integrates experimental and applied research, the QL movement will have the chance to show that it is not merely l'art pour l'art, but indeed is beneficial to society. Received: 28 September 1998 / Accepted: 14 October 1998  相似文献   
148.
Summary The pathogenetic relationship between tumour and hypertension was investigated in 129 patients with renal cell carcinoma, of whom 41 (31.8%) were hypertensive. Of these 41 patients with renal tumours and hypertension, 6 (14.6%) were found to have primary reninism. In these patients the plasma renin activity in blood from the renal veins showed a tumour kidney to contralateral kidney ratio of between 4 and 7, and 2 patients also had secondary hyperaldosteronism. In the same 6 cases the renin content in the renal tumour tissue was significantly higher than that in tissue from the adjacent tumour-free renal cortex of the ipsilateral kidney. Immunohistochemical demonstration of renin in the tumour was only possible in these 6 cases. In 5 of these patients blood pressure returned to normal following nephrectomy; in the 6th case there was a drop in blood pressure after nephrectomy. In 3 renin-positive tumours examined, autonomous renin production was demonstrated in cell culture. Renin-producing renal cell carcinomas are an uncommon cause of renal hypertension. The differential diagnosis of hypertension should therefore also include renal tumour.  相似文献   
149.
为探讨人食管癌组织中热休克蛋白 70 (HSP70 )和糖调节蛋白 94( grp94)的表达及意义 ,采用SABC法检测人食管癌组织HSP70和grp94的表达 ,镜下观察HSP70和 grp94在癌组织及癌旁组织中的表达特点。结果 :92 .6%( 5 0 /5 4)食管癌组织中存在HSP70的表达 ,癌细胞存在胞质、胞核表达强度及部位的差异 ;而 grp94的表达阳性率为70 .4% ( 3 8/5 4) ,以胞质表达为主 ,而癌旁组织表达较少。提示 :人食管癌组织存在HSP70和 grp94的表达异质性 ,呈现了胞质、胞核的表达差异 ,HSP70和 grp94在人食管癌组织的表达特点为以后肿瘤抗原肽肿瘤疫苗的提取和实验奠定了基础。  相似文献   
150.
良性淋巴上皮病、淋巴上皮癌、MALT淋巴瘤的关系   总被引:1,自引:0,他引:1  
良性淋巴上皮病(benign lymphoepithelial lesion)、淋巴上皮癌(lymphoepithelial carcinoma)、黏膜相关淋巴组织型结外边缘区B细胞淋巴瘤(MALT淋巴瘤)(extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue,MALT lymphoma)是3种性质不同但又存在某些关联的病变,本文对3种病变的病因、组织病理学表现及三者之间的关系进行了介绍,并结合叶为民等论文中的一些内容进行了简要探讨。  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