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   9055篇
  免费   537篇
  国内免费   48篇
耳鼻咽喉   85篇
儿科学   284篇
妇产科学   145篇
基础医学   1189篇
口腔科学   239篇
临床医学   835篇
内科学   2178篇
皮肤病学   346篇
神经病学   687篇
特种医学   400篇
外国民族医学   3篇
外科学   1554篇
综合类   82篇
一般理论   1篇
预防医学   695篇
眼科学   94篇
药学   440篇
中国医学   6篇
肿瘤学   377篇
  2021年   119篇
  2020年   91篇
  2019年   99篇
  2018年   150篇
  2017年   148篇
  2016年   130篇
  2015年   172篇
  2014年   203篇
  2013年   301篇
  2012年   327篇
  2011年   384篇
  2010年   228篇
  2009年   232篇
  2008年   311篇
  2007年   391篇
  2006年   346篇
  2005年   330篇
  2004年   322篇
  2003年   316篇
  2002年   296篇
  2001年   295篇
  2000年   273篇
  1999年   279篇
  1998年   161篇
  1997年   155篇
  1996年   134篇
  1995年   109篇
  1994年   100篇
  1993年   85篇
  1992年   191篇
  1991年   141篇
  1990年   186篇
  1989年   193篇
  1988年   177篇
  1987年   167篇
  1986年   150篇
  1985年   147篇
  1984年   147篇
  1983年   106篇
  1982年   60篇
  1981年   55篇
  1980年   69篇
  1979年   95篇
  1978年   73篇
  1977年   61篇
  1975年   56篇
  1974年   65篇
  1973年   60篇
  1972年   70篇
  1970年   54篇
排序方式: 共有9640条查询结果,搜索用时 15 毫秒
21.
Unilateral intranigral injections of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and MPP+ (1-methyl-4-phenylpyridine) were given to young rats and unilateral intranigral injections of MPTP were given to old rats. MPTP in old rats and MPP+ in young rats induced ipsiversive circling for at least one week after injection and contraversive circling after the systemic administration of apomorphine; the number of D-2 receptors (Bmax) in the striatum of the injected hemisphere increased compared with that of control rats. MPTP in young rats induced only short-lasting ipsiversive circling and no contraversive circling after apomorphine; the number of striatal D-2 receptors did not increase. These results suggest that the neurotoxicity of MPTP is age-dependent in the rat, and that MPTP has neurotoxic effects on the nigrostriatal dopaminergic system in old rats and induces dopamine receptor supersensitivity in the denervated striatum.  相似文献   
22.
Metastatic liver disease can modify the metabolic response to critical illness. Systemic lactic acidosis may arise from an increased production due to inadequate peripheral tissue oxygen transport, altered metabolic function such as depressed pyruvate oxidation or insufficient hepatic clearing capacity due to tumor replacement of functional liver mass. Hepatic venous catheterization in a patient with extensive metastatic melanoma to the liver and adult respiratory distress syndrome indicated a marked disparity between whole body and liver oxygenation which may arise due to a markedly stepped up splanchnic oxygen utilization unmatched by a proportionate rise in regional oxygen delivery. Since some neoplasms may exhibit increased metabolic activity, it is suspected that these metastatic lesions may have contributed to the observed regional hypermetabolism thereby worsening hepatic hypoxia and exacerbating lactic acidosis. This case also illustrates the difficulties in interpreting global indicators of metabolic function and oxygenation in critically ill patients.  相似文献   
23.
The polymerase chain reaction (PCR) was used to detect varicella zoster virus (VZV) DNA in vesicle samples from patients with varicella and zoster. Primers and the oligonucleotide probe were chosen from the region of the immediate early gene 63. Procedures for preparing the DNA from the specimens were omitted, and the amplified DNA was directly detected in ethidium bromide-stained polyacrylamide or agarose gels, thus providing a rapid and less laborious assay. A total of 66 vesicle specimens including 3 crusts (collected on days 1-14 after the onset of exanthem) were tested by the simplified VZV-PCR, and 64 (97%) were positive. When the direct visualization of the amplified DNA was confirmed by DNA hybridization, a non-radioactive hybridization assay involving a digoxigenin-labelled oligonucleotide probe and detection by chemiluminescence proved as adequate as a radioactive hybridization assay. Thus, the VZV PCR described appears to be a useful diagnostic test for detecting and identifying varicella zoster virus.  相似文献   
24.
合成了18个O,O′-二烷基-O″-(5-取代-3-苯并噻吩乙腈肟)磷酸酯及硫代磷酸酯类化合物(Ⅰ1~18)。初步杀螺试验结果表明,其中5个化合物,即Ⅰ2,3,7,11,12有明显的杀螺增效作用。  相似文献   
25.
Extended -spectrum β -lactamases(ESBLs)aremainlyproducedbymembersofthefamilyEnter obacteriaceaewhichcanhydrolyzeβ -lactamantibi oticsincludingthethird - generationcephalosporinandaztreonam ,theESBLs- producingbacillishowedmedian -highresistancetoceftazidimeandaztreonamparticularly[1] .NowadaystheprevalenceofESBLs -producingstrainshavebeenreportedinmanyareasaroundtheworld[2 ] .ButthereisfewinformationabouttherelationshipbetweentheuseofantibioticandtheproductionofESBLs .Weperformedastud…  相似文献   
26.
27.
V Lange 《Endoscopy》1986,18(5):195-196
Gastric bezoars, especially those of the phytobezoar type, are a rare sequela of gastroduodenal surgery or other uncommon circumstances. When they produce symptoms, removal is always necessary. In the past, treatment has shifted from surgical to non-surgical intervention, of which gastric lavage and/or slow enzymatic dissolution have been attempted. A safe, simple and rapid endoscopic method for the removal of the bezoar has previously been reported by 3 authors. With our two patients there are now ten cases of successful fragmentation of phytobezoars by this technique using a pulsating jet of water through the endoscope. This success recommends the procedure as treatment of choice, and it should be used more widely.  相似文献   
28.
29.
30.
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