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   1954篇
  免费   97篇
  国内免费   5篇
耳鼻咽喉   28篇
儿科学   83篇
妇产科学   127篇
基础医学   265篇
口腔科学   111篇
临床医学   152篇
内科学   270篇
皮肤病学   29篇
神经病学   206篇
特种医学   201篇
外科学   167篇
综合类   18篇
预防医学   102篇
眼科学   5篇
药学   171篇
  1篇
中国医学   1篇
肿瘤学   119篇
  2023年   16篇
  2022年   16篇
  2021年   50篇
  2020年   24篇
  2019年   38篇
  2018年   34篇
  2017年   39篇
  2016年   41篇
  2015年   51篇
  2014年   48篇
  2013年   64篇
  2012年   120篇
  2011年   127篇
  2010年   61篇
  2009年   56篇
  2008年   89篇
  2007年   79篇
  2006年   83篇
  2005年   94篇
  2004年   83篇
  2003年   58篇
  2002年   69篇
  2001年   55篇
  2000年   54篇
  1999年   65篇
  1998年   36篇
  1997年   35篇
  1996年   25篇
  1995年   25篇
  1994年   18篇
  1993年   15篇
  1992年   22篇
  1991年   24篇
  1990年   24篇
  1989年   32篇
  1988年   30篇
  1987年   29篇
  1986年   29篇
  1985年   19篇
  1984年   10篇
  1983年   11篇
  1982年   10篇
  1981年   12篇
  1978年   13篇
  1976年   7篇
  1972年   11篇
  1970年   8篇
  1969年   10篇
  1968年   11篇
  1967年   8篇
排序方式: 共有2056条查询结果,搜索用时 15 毫秒
1.
A simple and rapid fluorimetric method for the determination of 9-fluoro-10-[N-(4′-methyl)piperazinyl]-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-d,e][1–4]benzothyazin-6-carboxylic acid hydrochloride (MF 934), in serum and in pharmaceutical formulations, has been developed based on its strong fluorescence, in 0.1 N H2SO4, at 526 nm (excitation wavelength at 340 nm). The procedure which involves the direct dilution of the sample requires only a few minutes and the sample volume is only 20–100 μl of serum, depending on the drug concentration. Tedious sample preparation procedures such as extraction, deproteinization, or centrifugation are not necessary. The minimum concentration that can be detected is 0.3 ng ml−1, the standard curve in 0.1 N H2SO4 was found to be linear from 0.005 to 1.5 μg ml−1 and from 0.01 to 0.07 g in plasma after dilution with 0.1 N H2SO4.  相似文献   
2.
3.
Keratodermia is an incurable genetic and regional disease located in the palmar and plantar regions. The author reports his experience with five cases of palmoplantar keratodermia that were treated by grafting onto the soles and the palms skin taken from the calves and the thighs.  相似文献   
4.
The compound IBI-P-05006, 2-(6'-carboxyhexyl)-3-n-hexylcyclohexylamine, is an antiaggregating agent under development. IBI-P-05006 is an in vitro inhibitor of platelet aggregation. The biotransformation of this compound has been studied in the dog and rat. We present here a study on the metabolites of IBI-P-05006 found in dog and rat urine, and in dog plasma. Analyses were done by gas chromatography-mass spectrometry. In dog urine 15 metabolites were identified. Some of them were also found in dog plasma and in rat urine. The unmetabolized drug was found only in plasma. 10 different hydroxylated metabolites were characterized. The hydroxyl groups were introduced in the hexyl chain in positions omega-4, omega-3, omega-2, omega-1 and omega.  相似文献   
5.
OBJECTIVES: To evaluate the accuracy of sonographic identification of the site of umbilical cord insertion (CI) at 18-20 weeks of gestation, to compare the sensitivities for detection of a velamentous cord insertion (VCI) secondary to a CI into the anterior, posterior or fundal wall, and to compare the intrapartum complications secondary to VCI into the upper, middle or lower third of the uterus. METHODS: As part of the routine ultrasound scan at 18-20 weeks' gestation we evaluated abnormal CI (VCI and marginal CI) and the location of the CI in the uterus in 3446 pregnancies. In cases of abnormal CI, the location of the CI was further classified as being in the upper, middle or lower third of the uterus. After delivery, the placenta and the umbilical cord were examined and intrapartum complications were compared with the location of the CI. RESULTS: The values for antenatal detection of VCI were: sensitivity, 25 of 40 (62.5%); positive predictive value, 25 of 25 (100%); and negative predictive value, 3406 of 3421 (99.6%). The sensitivity for cases in which the CI was located on the anterior wall was 12 of 13 (92.3%); when it was located on the posterior wall, the sensitivity was 11 of 22 (50.0%); and when it was fundal the sensitivity was 2 of 5 (40.0%). Variable decelerations were frequently observed with a VCI. In lower VCI cases, non-reassuring fetal heart rate patterns and emergency Cesarean sections occurred with a higher frequency than in cases with upper or middle VCI (P < 0.01). After delivery, the length of the aberrant vessels in cases of VCI by pathologic examination was 3.9 +/- 3.3 cm in the upper third, 4.7 +/- 4.6 cm in the middle third, and 10.6 +/- 6.8 cm in the lower third; thus, the aberrant vessel length was significantly greater when the CI was in the lower third of the uterus (P = 0.024). CONCLUSION: We have demonstrated that VCI with a lower CI site and with longer aberrant vessels is associated with various intrapartum complications. This finding has the potential for improving perinatal outcome.  相似文献   
6.
Solitary bronchioloalveolar carcinoma: CT criteria   总被引:14,自引:0,他引:14  
The computed tomographic (CT) scans of 30 patients with solitary bronchioloalveolar carcinoma were reviewed. Common features at CT included the peripheral or subpleural location of a pulmonary mass (25 cases), pseudocavitation (18 cases), heterogeneous attenuation (17 cases), irregular margins forming a star pattern (22 cases), and pleural tags (21 cases). Using these CT criteria, four independent observers attempted to identify cases of bronchioloalveolar carcinoma from a larger sample of lung cancers and benign lesions by categorizing a series of test cases into four probability categories. Although the bronchioloalveolar carcinomas were correctly ranked in the two highest probability categories 75% of the time (in 45 of 60 cases), there was considerable overlap with other lung lesions, particularly with adenocarcinoma and large cell undifferentiated carcinoma. However, even though the typical features of bronchioloalveolar carcinoma are not invariable or highly specific, they are characteristic enough to suggest the diagnosis.  相似文献   
7.
Toxic pustuloderma associated with azithromycin   总被引:1,自引:0,他引:1  
  相似文献   
8.
9.
10.
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