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   1003篇
  免费   56篇
  国内免费   14篇
耳鼻咽喉   31篇
儿科学   5篇
妇产科学   12篇
基础医学   132篇
口腔科学   14篇
临床医学   168篇
内科学   227篇
皮肤病学   5篇
神经病学   46篇
特种医学   59篇
外科学   194篇
综合类   5篇
预防医学   36篇
眼科学   16篇
药学   29篇
中国医学   1篇
肿瘤学   93篇
  2023年   6篇
  2022年   16篇
  2021年   23篇
  2020年   18篇
  2019年   23篇
  2018年   33篇
  2017年   21篇
  2016年   27篇
  2015年   30篇
  2014年   49篇
  2013年   76篇
  2012年   81篇
  2011年   72篇
  2010年   51篇
  2009年   43篇
  2008年   61篇
  2007年   62篇
  2006年   69篇
  2005年   51篇
  2004年   51篇
  2003年   44篇
  2002年   47篇
  2001年   14篇
  2000年   17篇
  1999年   15篇
  1998年   6篇
  1997年   10篇
  1996年   3篇
  1995年   5篇
  1994年   3篇
  1993年   2篇
  1991年   4篇
  1990年   4篇
  1989年   3篇
  1988年   2篇
  1987年   3篇
  1986年   2篇
  1984年   2篇
  1979年   2篇
  1975年   2篇
  1968年   1篇
  1964年   1篇
  1962年   2篇
  1931年   1篇
  1901年   2篇
  1897年   1篇
  1895年   1篇
  1892年   1篇
  1891年   1篇
  1888年   1篇
排序方式: 共有1073条查询结果,搜索用时 234 毫秒
1.
OBJECTIVE: A prospective randomized study was conducted in order to analyze the role of fibrinolytics in the treatment of complicated parapneumonic effusion. METHODS: From 2001 to 2004, 127 consecutive patients were managed for thoracic empyema. In all cases the cause was bacterial pneumonia. Seventy patients were managed with sole tube thoracostomy (group A) and 57 with combination of tube thoracostomy and streptokinase instillation (group B). Groups were statistically compared for the age, gender, duration of symptoms, quality of pleural fluid, chest imaging, complete drainage, length of hospital stay and mortality. Multivariate analysis was used in order to define the factors that affect outcome. RESULTS: Tube thoracostomy was successful in 47 (67.1%) cases (group A), while fibrinolysis led to a favorable outcome in 50 cases (87.7%) (P<0.05). The length of stay in thoracic surgical department was significantly longer for group A (P<0.001). Mortality rate in group A was significantly higher (P<0.001). Multiple regression analysis disclosed as sole independent favorable factor for pleural drainage, the use of fibrinolysis during the course of chest tube drainage (P=0.006, odds ratio 4.29, 95% CI 1.51-12.14). CONCLUSIONS: Fibrinolytic agents are a useful adjunct in the management of complicated parapneumonic effusions. Intrapleural fibrinolytics, if used early in the fibrinopurulent stage of a parapneumonic effusion, decrease the rate of surgical interventions (VATS or open decortcation) and the length of hospital stay with minor associated morbidity.  相似文献   
2.
Respiratory gating based on external surrogates is performed in many clinics. We have developed a new technique for treatment verification using an electronic portal imaging device (EPID) in cine mode for gated 3D conformal therapy. Implanted radiopaque fiducial markers inside or near the target are required for this technique. The markers are contoured on the planning CT set, enabling us to create digitally reconstructed radiographs (DRRs) for each treatment beam. During the treatment, a sequence of EPID images can be acquired without disrupting the treatment. Implanted markers are visualized in the images and their positions in the beam's eye view are calculated off-line and compared to the reference position by matching the field apertures in corresponding EPID and DRR images. The precision of the patient set-up, the placement of the beam-gating window, as well as the residual tumour motion can be assessed for each treatment fraction. This technique has been demonstrated with a case study patient, who had three markers implanted in his liver. For this patient, the intra-fractional variation of all marker positions in the gating window had a 95% range of 4.8 mm in the SI direction (the primary axis of motion). This was about the same (5 mm) as the residual motion considered in the planning process. The inter-fractional variation of the daily mean positions of the markers, which indicates the uncertainty in the set-up procedure, was within +8.3 mm/-4.5 mm (95% range) in the SI direction for this case.  相似文献   
3.
Ghrelin is a novel peptide that stimulates the release of growth hormone from the pituitary and is involved in hypothalamic feeding regulation. A pre-embedding immunostaining technique was used to study the ultrastructure and synaptic relationships of ghrelin-containing neurons in the rat arcuate nucleus (ARC). Ghrelin-like immunoreactive (ghrelin-LI) neurons were found in the ARC, and were especially abundant in its ventral part. At the electron microscopic level, ghrelin-LI neurons received afferent synapses from many unknown axon terminals. Ghrelin-LI products in the immunoreactive cell bodies, processes, and axon terminals were detected mainly in dense granular vesicles about 110 nm in diameter. Ghrelin-LI presynaptic axon terminals often made synapses with unknown immunonegative neurons. These results suggest that ghrelin acts to regulate food intake through synaptic connections in hypothalamic neuronal networks.  相似文献   
4.
Biallelic BRCA2-mutations can cause Fanconi anemia and are found in approximately 7% of pancreatic cancers. Recently, several sequence changes in FANCC and FANCG were reported in pancreatic cancer. Functional defects in the Fanconi pathway can result in a marked hypersensitivity to interstrand crosslinking agents, such as mitomycin C. The functional implications of mutations in the Fanconi pathway in cancer have not been fully studied yet; these studies are needed to pave the way for clinical trials of treatment with crosslinking agents of Fanconi-defective cancers. The competence of the proximal Fanconi pathway was screened in 21 pancreatic cancer cell lines by an assay of Fancd2 monoubiquitination using a Fancd2 immunoblot. The pancreatic cancer cell lines Hs766T and PL11 were defective in Fancd2 monoubiquitination. In PL11, this defect led to the identification of a large homozygous deletion in FANCC, the first cancer cell line found to be FANCC-null. The Fanconi-defective cell lines Hs766T, PL11, and CAPAN1 were hypersensitive to the crosslinking agent mitomycin C and some to cis-platin, as measured by cell survival assays and G(2)/M cell-cycle arrest. These results support the practical exploration of crosslinking agents for non-Fanconi anemia patients that have tumors defective in the Fanconi pathway.  相似文献   
5.
The contribution of group III and IV muscle nociceptors activated by injection of KCl or bradykinin into the muscle artery (i.a.) of the gastrocnemius-soleus muscle to spinal motor reflex pathways was investigated in high spinal cats. Group I-III fibres were completely blocked by TTX, leaving group IV-fibre conduction intact. Thus, effects from i.a. KCl or bradykinin injection persisting after TTX were attributed to TTX resistant group IV fibres while the contribution of group III fibres was approximately defined by the difference between those effects and the control effects before TTX. Confirming former findings the chemical activation of group III and IV muscle afferents induced distinct reflex facilitation of the flexor posterior biceps semitendinosus and inhibition of the extensor quadriceps. After the block of all myelinated fibres by TTX the same stimuli induced only minor reflex effects mediated by the persistently conducting TTX resistant group IV afferents. It is concluded that the main functional meaning of group IV muscle afferents, which respond preferentially with a higher threshold to mechanical stimuli, is probably less related to reflex motor control than that of group III afferents.  相似文献   
6.
PURPOSE: BRCA2, FANCC, and FANCG gene mutations are present in a subset of pancreatic cancer. Defects in these genes could lead to hypersensitivity to interstrand cross-linkers in vivo and a more optimal treatment of pancreatic cancer patients based on the genetic profile of the tumor. EXPERIMENTAL DESIGN: Two retrovirally complemented pancreatic cancer cell lines having defects in the Fanconi anemia pathway, PL11 (FANCC-mutated) and Hs766T (FANCG-mutated), as well as several parental pancreatic cancer cell lines with or without mutations in the Fanconi anemia/BRCA2 pathway, were assayed for in vitro and in vivo sensitivities to various chemotherapeutic agents. RESULTS: A distinct dichotomy of drug responses was observed. Fanconi anemia-defective cancer cells were hypersensitive to the cross-linking agents mitomycin C (MMC), cisplatin, chlorambucil, and melphalan but not to 5-fluorouracil, gemcitabine, doxorubicin, etoposide, vinblastine, or paclitaxel. Hypersensitivity to cross-linking agents was confirmed in vivo; FANCC-deficient xenografts of PL11 and BRCA2-deficient xenografts of CAPAN1 regressed on treatment with two different regimens of MMC whereas Fanconi anemia-proficient xenografts did not. The MMC response comprised cell cycle arrest, apoptosis, and necrosis. Xenografts of PL11 also regressed after a single dose of cyclophosphamide whereas xenografts of genetically complemented PL11(FANCC) did not. CONCLUSIONS: MMC or other cross-linking agents as a clinical therapy for pancreatic cancer patients with tumors harboring defects in the Fanconi anemia/BRCA2 pathway should be specifically investigated.  相似文献   
7.
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