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   1588篇
  免费   69篇
  国内免费   4篇
耳鼻咽喉   7篇
儿科学   80篇
妇产科学   5篇
基础医学   297篇
口腔科学   16篇
临床医学   94篇
内科学   352篇
皮肤病学   16篇
神经病学   95篇
特种医学   35篇
外科学   421篇
综合类   2篇
预防医学   40篇
眼科学   12篇
药学   105篇
中国医学   1篇
肿瘤学   83篇
  2023年   8篇
  2022年   16篇
  2021年   28篇
  2019年   32篇
  2018年   24篇
  2017年   15篇
  2016年   21篇
  2015年   27篇
  2014年   28篇
  2013年   37篇
  2012年   62篇
  2011年   61篇
  2010年   45篇
  2009年   39篇
  2008年   61篇
  2007年   69篇
  2006年   65篇
  2005年   66篇
  2004年   62篇
  2003年   59篇
  2002年   85篇
  2001年   70篇
  2000年   58篇
  1999年   49篇
  1998年   27篇
  1996年   12篇
  1995年   9篇
  1994年   15篇
  1993年   16篇
  1992年   41篇
  1991年   50篇
  1990年   45篇
  1989年   57篇
  1988年   40篇
  1987年   51篇
  1986年   36篇
  1985年   34篇
  1984年   20篇
  1983年   7篇
  1981年   5篇
  1979年   14篇
  1978年   8篇
  1977年   9篇
  1976年   9篇
  1974年   8篇
  1973年   5篇
  1971年   7篇
  1968年   6篇
  1967年   5篇
  1966年   5篇
排序方式: 共有1661条查询结果,搜索用时 15 毫秒
71.
72.
The histological and histochemical findings in the respiratory muscles of a patient with severe neonatal nemaline myopathy are described. The patient suffered from frequent pneumonia associated with vomiting due to gastroesophageal reflux and died at 3 months from respiratory failure. The diaphragm was moderately involved and the intercostal muscles mildly involved. Core/targetoid structures were observed in the diaphragm and intercostal muscles.  相似文献   
73.
A new Ph1-positive leukemic cell line (MC3) expressing the P210ber/abl oncoprotein was established from a patient with CML in blast crisis. The MC3 cells showed the trilineage phenotype of myeloid, lymphoid (CD 19) and megakaryocytoid lineages, and had a proliferative response to rhIL-1 and rhIL-3 in the serum-free culture. These results and the expression of CD34 indicated that the MC3 cells have characteristics of hematopoietic progenitor cells. Recently, it has been documented that alterations of the p53 gene in leukemic cells are frequently detected during the blast crisis of CML. The MC3 cells contained the altered p53 gene. In addition, the original leukemic cells showed the point-mutational activation of the N-ras gene and an additional chromosomal abnormality inv(3q), but the MC3 cells contained no such abnormalities, indicating that not all of the original leukemic cells had these abnormalities. Thus, the MC3 cell line may provide several insights into investigations of the blast crisis in CML as well as hematopoietic progenitor cells.  相似文献   
74.
We describe a 37-year-old man complaining of right back pain and gait disturbance. He had a big soft tumor on his right back, hemihypertrophy of the right lower extremity, and right thoracic scoliosis. We diagnosed Klippel-Trenaunay-Weber syndrome based on the pathological findings of the soft tumor. Computed tomography (CT) scan revealed severe spinal stenosis due to a hypertrophic vertebral body and facet joint at T7. Treatment by decompression of hypertrophic bone led to complete neurological recovery. To our knowledge, no case has been reported of Klippel-Trenaunay-Weber syndrome with myelopathy which originated from thoracic scoliosis with a hypertrophic facet joint and vertebral body. We suggest that the cause of myelopathy in Klippel-Trenaunay-Weber syndrome originated not only from arteriovenous fistula, medullary angioma, and extradural hemangioma but also vertebral hypertrophy with scoliosis.  相似文献   
75.
BACKGROUND: It is still disputed whether gastric atrophy or intestinal metaplasia improves after the cure of Helicobacter pylori infection. AIM: To clarify the histological changes after the cure of H. pylori infection through a literature survey. METHODS: Fifty-one selected reports from 1066 relevant articles were reviewed. The extracted data were pooled according to histological parameters of gastritis based on the (updated) Sydney system. RESULTS: Activity improved more rapidly than inflammation. Eleven of 25 reports described significant improvement of atrophy. Atrophy was not improved in one of four studies with a large sample size (> 100 samples) and in two of five studies with a long follow-up period (> 12 months), suggesting that disagreement between the studies was not totally due to sample size or follow-up period. Methodological flaws, such as patient selection, and statistical analysis based on the assumption that atrophy improves continuously and generally in all patients might be responsible for the inconsistent results. Four of 28 studies described significant improvement of intestinal metaplasia [corrected]. CONCLUSIONS: Activity and inflammation were improved after the cure of H. pylori infection. Atrophy did not improve generally among all patients, but improved in certain patients. Improvement of intestinal metaplasia was difficult to analyse due to methodological problems including statistical power.  相似文献   
76.
Recently, it has been suggested that neural stem cells and neural progenitor cells exist in the ependyma that forms the central canal of the spinal cord. In this study, we produced various degrees of thoracic cord injury in adult rats using an NYU-weight-drop device, assessed the degree of recovery of lower limb motor function based on a locomotor rating scale, and analyzed the kinetics of ependymal cell proliferation and differentiation by proliferating cell nuclear antigen (PCNA), nestin, glial fibrillary acidic protein (GFAP), or GAP-43 immunostaining. The results showed that the time course of the ependymal cell proliferation and differentiation reactions differed according to the severity of injury, and that the responses occurred not only in the neighborhood of the injury but in the entire spinal cord. An increase in the locomotor rating score was related to an increase in the number of PCNA-positive cells, and the differentiation of ependymal cells into reactive astrocytes was involved in injury repair. No apoptotic cells in the ependyma were detectable by the TUNEL method. These results indicate that the ependymal cells of the spinal central canal are themselves multipotent, can divide and proliferate according to the severity of injury, and differentiate into reactive astrocytes within the ependyma without undergoing apoptosis or cell death.  相似文献   
77.
Reduced bone mineral density (BMD) and an increased risk of vertebral fracture have been reported in calcium-stone-forming (CSF) patients presenting with idiopathic hypercalciuria. We investigated the association between BsmI vitamin D receptor (VDR) polymorphism and BMD in 68 hypercalciuric CSF patients (35 males and 33 premenopausal females, mean age +/- SD = 39 +/- 10 years). BMD was measured at lumbar spine (L2-L4) and femur neck sites using dual energy X-ray absorptiometry. A 72-hour dietary record and a 24-hour urine sample were obtained from each patient to determine calcium intake and excretion. The allelic frequency found for the sample as a whole was 16% BB, 44% Bb and 40% bb. Mean BMD values did not significantly differ among BB, Bb and bb patients at L2-L4 (1.162 +/- 0.10, 1.133 +/- 0.11 and 1.194 +/- 0.19 g/cm2, mean +/- SD, respectively) or at neck sites (0.920 +/- 0.11, 0.931 +/- 0.15 and 0.982 +/- 0.15 g/cm2, respectively). Calcium intake and excretion were also not significantly different among the three genotypes. Patients were then divided into two groups, normal BMD, T-score > or =-1 (n = 34) and low BMD, T-score <-1 (n = 34), to further evaluate the allele influence on previous bone loss. Despite a trend for a higher mean BMD at spine or neck sites for patients with one or two b alleles when compared to BB patients, the difference did not reach statistical significance. The distribution of BB, Bb and bb genotypes in the low-bone-mass group (15, 47 and 38%, respectively) was similar to that in the normal-bone-mass group (18, 41 and 14%, respectively). These data suggest that BsmI VDR polymorphism does not play an important role in the bone loss seen in hypercalciuric CSF patients.  相似文献   
78.
Responses of hepatic glucose output (HGO) to noxious mechanical stimulation of different skin areas were investigated in anaesthetised rats with central nervous system intact or acutely spinalized at the thoracic 1-2 (T1-T2) level by focusing on the involvement of the sympathetic and parasympathetic nerves in the responses of HGO. We measured HGO with a microdialysis probe implanted into the left lateral lobe of the liver. Pinching was applied to bilateral skin areas of the abdomen and hindlimb for 10 min. Atropine was injected in order to block the action of the parasympathetic nerves, whereas phentolamine and propranolol were injected in order to block the action of the sympathetic nerves. The HGO started to increase immediately after the cessation of pinching of the abdomen and the hindlimb, and lasted for 30 min. The increase of HGO was observed during stimulus period in animals pretreated with atropine, and totally abolished in animals pretreated with phentolamine and propranolol. The responses of HGO to abdominal pinching, but not to hindlimb pinching, remained after spinal cord transection at the T1-T2 level. The present results suggest that HGO is regulated as a reflex response via both sympathetic and parasympathetic nerves by noxious mechanical stimulation of the skin. Furthermore, it was shown that relative contribution of the spinal and supraspinal organization to the somato-HGO responses was dependent on the skin areas stimulated.  相似文献   
79.
A 8-year-old girl who underwent a total cavopulmonary connection as an one-staged repair for tricuspid atresia (Ic) had had a progressive dilated cardiomyopathy. Despite of any medical support, her left ventricular ejection fraction had been ranged from 10% to 20% since 4 months after Fontan operation. This patient was decided to apply for a heart transplantation in Germany 17 months after Fontan operation. An administration of the sufficient amount of inotropics and oxygen, volume resuscitation, reduction of the peripheral circulation at the time of take-off, and a meticulous monitoring may contribute to the successful transportation of the critically ill patient.  相似文献   
80.
BACKGROUND: Various vasoactive substances are released during cardiopulmonary bypass. They may deteriorate pulmonary circulation after the Fontan operation. Effects of plasma endothelin-1 (ET-1), a vasoconstricting peptide, on the Fontan circulation have not been investigated. METHODS: Eleven patients (aged 11.1+/-7.5 years) who underwent the modified Fontan operation (group F) and seven patients (aged 9.9+/-6.0 years) who underwent the biventricular repair (group C) were studied. Plasma samples were obtained for measuring ET-1 on the first postoperative day (Early I), on returning to floor care from the intensive care unit (Early II), and during postoperative cardiac catheterization (Late). RESULTS: Plasma concentrations of ET-1 increased in group F (Early I, 4.37+/-1.78 pg/ml; Early II, 4.07+/-1.90 pg/ml) as compared with the basal value of 1.0+/-0.5 pg/ml. The central venous pressure, which reflects the pulmonary circulatory state, soon after the Fontan operation correlated significantly with the increased ET-1 concentration (y=1.809 x+6.484; r=0.809; p=0.0026). Although the Late ET-1 concentrations in group F were significantly decreased, the central venous pressure and the ET-1 concentrations demonstrated a significant correlation (y=3.074 x +5.427; r=0.740; p=0.0227). CONCLUSIONS: The increased humoral vasoactive substances such as ET-1, which induces pulmonary vasoconstriction following the Fontan operation, may have important implications for the Fontan circulation.  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