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   840篇
  免费   57篇
  国内免费   20篇
儿科学   76篇
妇产科学   28篇
基础医学   100篇
口腔科学   34篇
临床医学   89篇
内科学   147篇
皮肤病学   17篇
神经病学   18篇
特种医学   121篇
外科学   139篇
综合类   13篇
预防医学   33篇
眼科学   15篇
药学   27篇
中国医学   2篇
肿瘤学   58篇
  2020年   8篇
  2019年   10篇
  2018年   11篇
  2017年   7篇
  2016年   9篇
  2015年   11篇
  2014年   18篇
  2013年   24篇
  2012年   23篇
  2011年   27篇
  2010年   22篇
  2009年   32篇
  2008年   28篇
  2007年   36篇
  2006年   23篇
  2005年   17篇
  2004年   13篇
  2003年   18篇
  2002年   18篇
  2001年   19篇
  2000年   14篇
  1999年   15篇
  1998年   38篇
  1997年   46篇
  1996年   32篇
  1995年   23篇
  1994年   22篇
  1993年   20篇
  1992年   9篇
  1991年   18篇
  1990年   27篇
  1989年   29篇
  1988年   21篇
  1987年   21篇
  1986年   19篇
  1985年   17篇
  1984年   11篇
  1983年   19篇
  1982年   13篇
  1981年   8篇
  1980年   17篇
  1979年   10篇
  1978年   10篇
  1977年   10篇
  1976年   12篇
  1975年   10篇
  1974年   9篇
  1973年   12篇
  1971年   4篇
  1966年   3篇
排序方式: 共有917条查询结果,搜索用时 15 毫秒
1.
The biodistribution of two recently developed tumour markers, trimethylated (CP(Me)3) and trimethoxylated (CP(OMe)3) carotenoporphyrin, was investigated by means of laser-induced fluorescence (LIF) after i.v. injection into 38 tumour-bearing (MS-2 fibrosarcoma) female Balb/c mice. At 3, 24, 48 or 96 h after administration, the carotenoporphyrin fluorescence was measured in tumoral and peritumoral tissue, as well as in the abdominal, thoracic and cranial cavities. The fluorescence was induced by a nitrogen laser-pumped dye laser, emitting light at 425 nm, and analysed by a polychromator equipped with an image-intensified CCD camera. The fluorescence was evaluated at 490, 655 and 720 nm: the second and third wavelengths represent the carotenoporphyrin (CP)-related peaks, whereas the first one is close to the peak of the tissue autofluorescence. The tumour and the liver were the two tissue types showing the strongest carotenoporphyrin-related fluorescence, whereas the cerebral cortex and muscle consistently exhibited weak substance-related fluorescence. In most tissue types, the fluorescence intensities decreased over time. A few exceptions were observed, notably the liver, in which the intensity remained remarkably constant over the time period investigated.  相似文献   
2.
3.
Zn-phthalocyanine (ZnPc) and Sn-etiopurpurin (SnET2) incorporated in unilamellar liposomes or solubilized in a Cremophor-EL emulsion have been incubated in vitro with rabbit plasma or intravenously administered to rabbits. Ultracentrifugation and chromatographic analysis of the plasma showed that ZnPc and SnET2 are mainly released to lipoproteins; within the lipoprotein family, both dyes are preferentially bound by low-density (LDL) and high-density (HDL) lipoproteins. The amount of dye bound with these two lipoprotein classes was related to their relative concentration in the plasma; in most cases a larger amount of photosensitizer was bound to HDL as compared to LDL on a protein concentration basis.  相似文献   
4.
5.
Metabolic adaptation of the chick embryo to chronic hypoxia   总被引:1,自引:0,他引:1  
  相似文献   
6.
A 23-year-old male patient who had no history of any previous medical illness was noted to have a widened mediastinum on chest X-ray undertaken as part of a routine medical evaluation. A computer tomographic (CT) scan confirmed the widened mediastinum to be due to a double superior vena cava (SVC). No further investigations were undertaken. The patient was noted to be well when re-assessed 3 years later.  相似文献   
7.
8.
9.
The vasa vasorum and angioplasty   总被引:2,自引:0,他引:2  
Interruption of flow in the vasa vasorum may lead to medial necrosis and aneurysm formation. The purpose of this study was to determine whether angioplasty produces significant alterations in the morphology or blood flow of the vasa vasorum of the dilated artery. The morphology of the canine vasa vasorum was studied before and after angioplasty; in a separate experiment vessel wall blood flow (VWBF) in canine carotid arteries was measured after angioplasty to determine whether physiologic regulation of the blood flow was disrupted by arterial dilation. No morphologic changes could be demonstrated in the vasa vasorum of the dilated artery; however, VWBF was increased by 1194 +/- 215% (mean +/- standard error, p less than 0.01) between 90 and 120 minutes after angioplasty. VWBF in the adjacent nondilated arterial segment was also increased (720 +/- 177% between 10-30 minutes, p less than 0.01) but returned toward normal after 60 minutes. Adenosine caused a "paradoxical" decrease in VWBF (p less than 0.05) of the dilated arterial segment while causing increased VWBF (p less than 0.05) in the thoracic aorta. Angioplasty appears to produce persistent hyperemia in the dilated arterial wall. A paradoxical response to adenosine suggests that vasa vasorum in the dilated arterial segment are maximally vasodilated. This may be due to mechanical disruption of vasomotor tone or to release of vasoactive substances.  相似文献   
10.
BACKGROUND: Boys and young men with hemophilia treated with factor infusions before 1985 had a substantial risk of acquiring the human immunodeficiency virus (HIV) and the acquired immunodeficiency syndrome. This study was designed to assess the effects of HIV and hemophilia per se on neurological function in a large cohort of subjects with hemophilia, and to investigate the relationships between neurological disease and death during follow-up. METHODS: Three hundred thirty-three boys and young men (207 HIV seropositive and 126 HIV seronegative) were evaluated longitudinally in a multicenter, multidisciplinary study. Neurological history and examination were conducted at baseline and annually for 4 years. The relationship between neurological variables, HIV serostatus, CD4+ cell counts, and vital status at the conclusion of the study was examined using logistic regression models. RESULTS: The risks of nonhemophilia-associated muscle atrophy, behavior change, and gait disturbance increased with time in immune compromised HIV-seropositive subjects compared with HIV seronegative or immunologically stable HIV-seropositive subjects. The risk of behavior change in immune compromised HIV-seropositive hemophiliacs, for example, rose to 60% by year 4 versus 10% to 17% for the other study groups. Forty-five subjects (13.5%), all of whom were HIV seropositive, died by year 4. Subjects who died had had increased risks of hyperreflexia, nonhemophilia-associated muscle atrophy, and behavior change. CONCLUSIONS: These results indicate that immune compromised, HIV-seropositive hemophiliacs have high rates of neurological abnormalities over time and that neurological abnormalities were common among subjects who later died. By contrast, immunologically stable HIV-seropositive subjects did not differ from the HIV-seronegative participants. Hemophilia per se was associated with progressive abnormalities of gait, coordination, and motor function.  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