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   10285篇
  免费   523篇
  国内免费   66篇
耳鼻咽喉   110篇
儿科学   189篇
妇产科学   148篇
基础医学   1178篇
口腔科学   243篇
临床医学   678篇
内科学   2768篇
皮肤病学   123篇
神经病学   628篇
特种医学   418篇
外科学   1877篇
综合类   62篇
一般理论   1篇
预防医学   311篇
眼科学   291篇
药学   568篇
中国医学   15篇
肿瘤学   1266篇
  2023年   77篇
  2022年   110篇
  2021年   193篇
  2020年   124篇
  2019年   146篇
  2018年   215篇
  2017年   173篇
  2016年   231篇
  2015年   206篇
  2014年   307篇
  2013年   286篇
  2012年   461篇
  2011年   553篇
  2010年   336篇
  2009年   258篇
  2008年   380篇
  2007年   443篇
  2006年   455篇
  2005年   464篇
  2004年   425篇
  2003年   370篇
  2002年   386篇
  2001年   362篇
  2000年   357篇
  1999年   304篇
  1998年   117篇
  1997年   83篇
  1996年   78篇
  1995年   85篇
  1994年   72篇
  1993年   79篇
  1992年   263篇
  1991年   214篇
  1990年   216篇
  1989年   254篇
  1988年   204篇
  1987年   209篇
  1986年   192篇
  1985年   183篇
  1984年   124篇
  1983年   109篇
  1979年   90篇
  1978年   66篇
  1977年   52篇
  1974年   41篇
  1973年   41篇
  1972年   42篇
  1971年   43篇
  1970年   45篇
  1968年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We describe a case history of a 24-year-old male with osteogenesis imperfecta (OI) who developed osteosarcoma of the left thigh. High-dose ifosfamide therapy caused marked tumor regression of multiple lung metastases. Immunohistochemically, the tumor cells were diffusely positive for the p53 protein. Mutation of the p53 gene was not detected by direct genomic sequencing of exons 4–8. The radiographic characteristics, including irregularly distributed osteolytic lesions and cortical discontinuity, should not be confused with hyperplastic callus formation, a benign process. A biopsy is critical to establish the differential diagnosis between osteosarcoma and common hyperplastic callus formation in OI; however, it must be applied with great care.  相似文献   
102.
103.
Summary The nucleotide sequences of tRNAAsn (GUU) and tRNATyr (GUA) genes from tomato mitochondria and their flanking regions have been determined. The tomato mitochondrial tRNAAsn gene is located 2.1 kb downstream from the tRNACys gene reported previously (Izuchi and Sugita 1989) and shows a nearly complete identity with the corresponding chloroplast gene. The tRNATyr gene, which shows only 73% homology with the corresponding chloroplast gene, has to be considered a native mitochondrial tRNA gene and is 535 bp from the chloroplast-like tRNAAsn gene on the same strand. Northern hybridization analysis revealed that the three tRNA genes are transcribed in tomato mitochondria. Southern hybridization analysis of tomato, sugar beet, rice and wheat mitochondrial DNAs, with oligonucleotide probes for mitochondrial or chloroplast tRNA genes, demonstrated that the mitochondrial tRNACys gene found in tomato is present in dicot plants but not in monocots. On the other hand, a chloroplast-like tRNACys gene exists in monocot plants.  相似文献   
104.
Summary The 1-adrenoceptor subtypes of dog prostate were characterized in binding and functional experiments. In saturation experiments, [3H]prazosin bound to 1-adrenoceptors with high affinity. In the displacement experiments, unlabelled prazosin and WB4101 biphasically inhibited the binding of 400 pM [3H]prazosin, suggesting the presence of at least two distinct affinity sites for prazosin or WB4101. The proportion of high-affinity sites was approximately 10%. HV723 also recognized two distinct affinity sites but the proportion of high-affinity sites was approximately 20%. From these results the presence of three distinct 1-adrenoceptor subtypes was suggested: presumably subtypes 1A (high affinity for prazosin and WB4101), 1N (high affinity for only HV723) and 1L (low affinity for the three antagonists) according to the recently proposed 1-adrenoceptor subclassification. The density of subtype 1L was much higher than that of subtypes 1A and 1N subtypes. In the functional experiments, prazosin, WB4101 and HV723 competitively antagonized the contractile response to noradrenaline with low affinities close to those estimated for the 1L subtypes. These results suggest that the contractile response to noradrenaline in the dog prostate is mediated predominantly through 1L subtype -adrenoceptors.  相似文献   
105.
A total of 573 cases of endometrial adenocarcinomas, composed of patients that had been hysterectomized from 1949 to 1985 at the Cancer Institute Hospital in Tokyo, have been clinicopathologically investigated to evaluate the degree of the myometrial invasion, meaning the "Depth" as a postoperative prognostic factor of this type of cancer. These patients were classified into groups, depending on the depth of the invasion. The Depth d group, showing a myometrial invasional depth of over two-thirds of the uterine wall, revealed a rate of 61.3% of the lymph node metastasis positive cases, and accounted for 50.0% of the postoperative survivals. These values were statistically worse, when compared to those of the Depth a to c groups, which showed less invasional depth. Thus it was concluded that "Depth" is an important prognostic factor in cases of an endometrial adenocarcinoma.  相似文献   
106.
A 51-year-old Japanese man who underwent a standard distal gastrectomy for cancer of the stomach developed abdominal pain when oral intake was commenced on the 6th postoperative day after an uneventful postoperative course. Complete obstruction of the jejunum led to a sudden deterioration in his general condition and a laparotomy was performed, revealing counterclockwise rotation of the mesenterium. The necrotic portion of the small intestine was removed, while 10 cm of the upper jejunum and 100 cm of the terminal ileum were preserved. His second postoperative course was uneventful apart from the development of intestinal hurry, which is now under medical control 9 months after his second laparotomy.  相似文献   
107.
We have previously demonstrated that treatment with L-cis diltiazem reduced cardiac infarct size in vivo. To examine the effect of L-cis diltiazem on Ca(2+) overload induced by ischemia/reperfusion, we used a model for Ca(2+) overload produced by metabolic inhibition in isolated guinea pig myocytes. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was quantified by fura-2 fluorescence microscopy and Ca(2+) overload was induced by inclusion of 1 microM of carbonyl cyanide m-chrolophenylhydrazone (CCCP) for 40 min treatment followed by washout for 30 min. This treatment caused a large [Ca(2+)](i) elevation as well as a sustained contracture of the cardiomyocytes. The increase was suppressed by 10 microM of 2-[2-[4-(4-nitrobenzyloxy) phenyl] ethyl] isothiourea methanesulphonate (KB-R7943), a specific inhibitor of the Na(+)/Ca(2+) exchanger, but not by nitrendipine (10 microM). L-cis Diltiazem (10 microM) attenuated the [Ca(2+)](i) increase, suggesting that L-cis diltiazem elicits a cardioprotective effect via attenuation of the [Ca(2+)](i) increase induced by metabolic inhibition and energy repletion.  相似文献   
108.
l-cis Diltiazem, an optical isomer of diltiazem, protects against myocardial dysfunction in vitro, whereas its Ca2+ channel blocking activity is about 100 times less potent than that of diltiazem. However, there is no evidence that l-cis diltiazem actually protects against ischemia/reperfusion injury in vivo. To assess this, we employed an anesthetized rabbit model, where the left circumflex artery was occluded for 15 min and reperfused for 360 min. Treatment with diltiazem before and during ischemia (bolus 200 microg/kg and 15 microg/kg per minute for 25 min, i.v.; 575 microg/kg total) showed slightly depressed hemodynamic parameters, while l-cis diltiazem (1150 microg/kg) had no effect. Treatment with l-cis diltiazem produced a high recovery of the thickening fraction and limited the infarct size in a dose-dependent manner. Furthermore, the treatment with l-cis diltiazem (1150 microg/kg) or diltiazem (575 microg/kg) 5 min before reperfusion also limited the infarct size, but not after reperfusion. These results suggest that l-cis diltiazem affects some events in the onset of reperfusion, independently of Ca2+-channel-blocking action. Our observations are the first to show that l-cis diltiazem demonstrated its cardioprotective action in the ischemic rabbit heart in vivo.  相似文献   
109.
Seventeen patients with pancreatic carcinoma were treated with intraoperative radiation therapy (IORT) combined with hyperthermia. Their treatment results were compared with those of 56 patients treated with the IORT alone (control group). The pain relief rate and the local tumor control rate of the hyperthermia group were slightly better than the control group. The survival rate of all patients was 13.7% at one year, 1.4% at two years (median, 5.0 months). The survival of the hyperthermia group was marginally better than that of the control group. Only 29% of the patients of the hyperthermia group was successfully heated, and if hyperthermia were given successfully to all patients, their prognoses would have been possibly improved.  相似文献   
110.
We divided cases of severe athetoid cerebral palsy originating perinatally into two groups neuropathologically, the "globo-Luysian group" (GL) and the "thalamo-putaminal group" (TP). The major abnormal sites in GL were the pallidum and subthalamic nucleus, and in TP the thalamus and putamen. The lesions in TP were more widespread and frequently accompanied by fibrillary gliosis in the central gray matter of the midbrain, and subthalamic nuclei were dominantly devastated. Concerning the etiology, GL and TP were related to perinatal severe jaundice and neonatal asphyxia, respectively. The patients in TP showed lower mental ability and suffered from more intractable convulsions than those in GL. In GL, rigidospasticity was frequently demonstrated with fluctuation of athetoid movements, while in TP various abnormalities of muscle tone were observed, with rather restricted athetosis.  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