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   376830篇
  免费   34842篇
  国内免费   25796篇
耳鼻咽喉   3135篇
儿科学   4128篇
妇产科学   5731篇
基础医学   44125篇
口腔科学   6728篇
临床医学   51901篇
内科学   56020篇
皮肤病学   3810篇
神经病学   20426篇
特种医学   13258篇
外国民族医学   229篇
外科学   36951篇
综合类   61249篇
现状与发展   91篇
一般理论   45篇
预防医学   24465篇
眼科学   11089篇
药学   40096篇
  394篇
中国医学   21462篇
肿瘤学   32135篇
  2024年   1209篇
  2023年   5683篇
  2022年   14474篇
  2021年   18306篇
  2020年   13908篇
  2019年   12175篇
  2018年   12923篇
  2017年   11661篇
  2016年   10849篇
  2015年   16565篇
  2014年   20682篇
  2013年   18641篇
  2012年   27636篇
  2011年   31079篇
  2010年   19767篇
  2009年   15677篇
  2008年   20376篇
  2007年   20405篇
  2006年   20249篇
  2005年   19874篇
  2004年   12655篇
  2003年   11636篇
  2002年   9762篇
  2001年   8632篇
  2000年   9072篇
  1999年   9606篇
  1998年   5925篇
  1997年   5830篇
  1996年   4530篇
  1995年   4363篇
  1994年   3694篇
  1993年   2415篇
  1992年   3050篇
  1991年   2599篇
  1990年   2186篇
  1989年   1868篇
  1988年   1632篇
  1987年   1398篇
  1986年   1086篇
  1985年   879篇
  1984年   529篇
  1983年   376篇
  1982年   208篇
  1981年   207篇
  1980年   144篇
  1979年   227篇
  1978年   111篇
  1977年   83篇
  1974年   94篇
  1972年   87篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
In1901,basedontheexperimentationwithbrittlewandstrokingcadaverskulls,LeFortfirstlyclassifiesmaxillofacialfracturesintothreetypes.Atpresent,theclassificationisstillusedtodistinguish clinicalmaxillofacialfracturesintheworld.1,2The diagnosisofLeForttypefracturereliesonthephysical andradiologicalexamination,butthephysicalfindings maynotalwaysbepresent.35Conventionalradiographs areroutinelyusedforLeForttypefracture,however,theoverlapofstructuremayimpairproper interpretationofimages.35Routinecomp…  相似文献   
942.
Epidermal growth factor receptor plays an important role in the pathogenesis of many malignancies. Various growth factors, including epidermal growth factor receptor, have been shown to influence pituitary tumor growth and differentiation. To analyze the role of epidermal growth factor receptor in pituitary tumor development, we examined normal pituitaries (n=8), pituitary adenomas (n=158), and pituitary carcinomas (n=7) for expression of epidermal growth factor receptor protein and messenger RNA using tissue microarrays and RT-PCR. We also examined (a) the expression of phospho-epidermal growth factor receptor, the activated form of epidermal growth factor receptor, in pituitary tumors and normal pituitaries by immunohistochemistry and (b) the effects on epidermal growth factor receptor expression of treating pituitary cells (HP75 cell line) with epidermal growth factor. Epidermal growth factor receptor and the phosphorylated variant expression were present in normal pituitary cells. Epidermal growth factor receptor messenger RNA was also detected in normal pituitaries, pituitary adenomas, and carcinomas by in situ hybridization and RT-PCR. Most pituitary adenomas showed expression of epidermal growth factor receptor and the phosphorylated variant. Nonfunctional adenomas showed higher levels of expression of epidermal growth factor receptor (76 vs 34%) and of phospho-epidermal growth factor receptor (26 vs 8%) as compared to functional adenomas. Five of seven pituitary carcinomas showed strong expression of both epidermal growth factor receptor and phospho-epidermal growth factor receptor. When a human pituitary cell line (HP75) was cultured in the presence of epidermal growth factor receptor, there was an increase in the levels of both epidermal growth factor receptor and phospho-epidermal growth factor receptor after 5 h of treatment, thus confirming that epidermal growth factor receptor signaling was active in pituitary tumors. These results indicate that activated epidermal growth factor receptor is expressed in pituitary adenomas and carcinomas. Higher levels in pituitary carcinomas suggest a role in pituitary tumor progression.  相似文献   
943.
目的 :探讨游离三碘甲状腺原氨酸 (FT3)的酶免疫测定法对于诊断甲状腺功能亢进和监测甲状腺激素补充治疗效果及预后情况的重要意义。方法 :采用聚苯乙烯96孔板作为固相载体 ,利用亲和纯化的兔抗T3 抗体和T3 - β-半乳糖苷酶标记物 ,建立了固相板竞争法。结果 :可测范围为0.48~45.0ng/L ,灵敏度0.13ng/L ,平均批内变异系数为 (n=20)6.4 % ,平均批间变异系数为 (n=8)12.4% ,正常参考范围4.14±0.97ng/L。正常人与甲亢病人能明显分开。结论 :酶免法测定血清FT3,其灵敏度、精密度均达到放免水平 ,且可避免同位素污染  相似文献   
944.
L-asparaginase, an effective antileukemia and antilymphoma agent, is toxic to many organ systems. We report a case of ureteral obstruction caused by L-asparaginase via the inflammatory complication of acute pancreatitis. The patient was an 11-year-old boy with acute lymphoblastic leukemia. Six days after completing a 4-week induction therapy containing 9 doses of L-asparaginase, severe left abdominal pain developed. Abdominal computed tomography showed phlegmon formation anterior to the pancreatic head and in the left posterior pararenal space. The strands of inflammatory soft tissues encased the upper third of the left ureter, causing left hydroureter and left hydronephrosis. The ureteral obstruction resolved after insertion of a double-J catheter that remained in place for 66 days. This case suggests that L-asparaginase may play a role in the pathogenesis of ureteral obstruction in children receiving chemotherapy.  相似文献   
945.
本文测定了208名生后5天内的新生儿阴茎长度,并对新生儿阴茎长度与胎龄、出生体重、出生身长的关系进行了探讨。结果为(1)成熟儿阴茎长度平均值±1SD为33.8±3.7mm,正常范围为26.4~41.2mm(平均值±2SD);(2)适于胎龄儿和小于胎龄儿阴茎长度与胎龄、出生体重、出生身长呈明显正相关;(3)大于胎龄儿阴茎长度平均值±1SD为34.6±3.2mm,正常范围与成熟儿相同。新生儿阴茎正常值的确定有助于小阴茎畸形的诊断和疗效的判断。  相似文献   
946.
Using a prospective hospital-based registry, 146 patients with transient ischaemic attack (TIA) were compared with 376 patients with minor first-ever ischaemic stroke with respect to the 3-month risk of subsequent vascular events, in order to clarify the distinctions between the disease entities. All patients were enrolled within 48 h of onset. The risk factor distribution for the two groups was comparable, except that the TIA patients had more previous TIAs. Large artery atherosclerosis (34%) and small vessel occlusion (32%) were the main aetiologies in the TIA group, whereas small vessel occlusion (49%) was the major cause in the stroke group. The 3-month risk of combined endpoints of stroke, myocardial infarction, and vascular death for TIA patients was higher than that for the minor stroke group (15.1% vs. 3.2%; hazard ratio 4.6, 95% confidence interval 2.3-9.3 in multivariate analysis). Large artery atherosclerosis and male sex were the other significant predictors. TIA may demand more urgent management than minor stroke. The fact that aetiology is a predictor, highlights the need for rapid diagnostic tests to establish pathogenesis.  相似文献   
947.
高效液相色谱法测定石杉碱甲片的含量   总被引:2,自引:0,他引:2  
采用高效液相色谱法测定石杉碱甲片的含量。固定相为μBondapak C18,流动相为乙腈-0.02mol/L磷酸二氢钾溶液(12:88),以对乙酰氨基酚为内标,石杉碱甲浓度在10 ̄50mg/L范围内与峰面积呈良好的线性关系,平均回收率为99.93%,RSD为0.41%(n=9)。  相似文献   
948.
949.
目的:研究脑缺血后脑片[Ca2+]i变化。方法:采用新型Ca2+荧光指示剂Fura-2双波长法测定兔大脑中动脉阻塞(MCAo)局灶脑缺血后脑片细胞内游离钙([Ca2+]i)。结果:脑缺血后脑组织[Ca2+]i显著升高。结论:[Ca2+]i在脑缺血损害中起重要作用。  相似文献   
950.
本文采用紫外分光光度法对国产盐酸吗啡普通片及合资厂产硫酸吗啡控释片于蒸馏水、人工胃液、人工肠液中进行体外溶出度和释放度测定。结果表明,两种片剂的溶释均符合中国药典95版标准,控释片在人工肠液中溶释参数T50、Td、m与在蒸馏水及人工胃液中的溶释参数差异具显著性(P<0.01),在人工肠液中的释放过程明显缓慢。  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