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   1753篇
  免费   127篇
  国内免费   3篇
耳鼻咽喉   6篇
儿科学   48篇
妇产科学   26篇
基础医学   219篇
口腔科学   29篇
临床医学   118篇
内科学   499篇
皮肤病学   21篇
神经病学   106篇
特种医学   54篇
外科学   314篇
综合类   53篇
预防医学   126篇
眼科学   43篇
药学   114篇
中国医学   21篇
肿瘤学   86篇
  2023年   22篇
  2022年   15篇
  2021年   102篇
  2020年   54篇
  2019年   87篇
  2018年   95篇
  2017年   64篇
  2016年   67篇
  2015年   61篇
  2014年   92篇
  2013年   131篇
  2012年   112篇
  2011年   127篇
  2010年   80篇
  2009年   57篇
  2008年   116篇
  2007年   116篇
  2006年   95篇
  2005年   85篇
  2004年   84篇
  2003年   60篇
  2002年   44篇
  2001年   19篇
  2000年   18篇
  1999年   9篇
  1998年   9篇
  1997年   2篇
  1996年   7篇
  1995年   3篇
  1994年   2篇
  1993年   2篇
  1992年   10篇
  1991年   4篇
  1990年   6篇
  1989年   2篇
  1988年   2篇
  1987年   3篇
  1986年   3篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1978年   2篇
  1976年   2篇
  1975年   1篇
  1973年   1篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1967年   1篇
  1890年   1篇
排序方式: 共有1883条查询结果,搜索用时 31 毫秒
1.
International Ophthalmology - Safety protocols are usually neglected among most of the trinitrotoluene (TNT)-exposed population, therefore, rendering the community prone to various...  相似文献   
2.
This study reports the first evaluation of sperm hyaluronan binding assay (HBA) for predicting the fertility of Nili-Ravi buffalo bulls in relation to standard parameters of sperm quality. Cryopreserved semen doses of low (n = 6), medium (n = 3) and high fertility (n = 8) bulls based on their respective return rates were used. Significantly, more spermatozoa bound to hyaluronan from the most fertile bulls (57.15% ± 1.44) compared with medium (42.46% ± 1.08) and low fertility bulls (29.70% ± 0.78). A strongly positive correlation (r = .824, p < .01) was found between HBA and fertility that predicts a 67.9% variability (r2 = .679, p < .01) in fertility. HBA was also strongly positively correlated with sperm viability (r = .679, p < .01) followed by their live/dead ratio (r = .637, p < .01), uncapacitated spermatozoa (r = .631, p < .01), normal apical ridge (r = .459, p < .01), motility (r = .434, p < .01), mature spermatozoa with low residual histones (r = .364, p < .01), high plasma membrane integrity (r = .316, p < .01) and nonfragmented DNA levels (r = .236, p < .05). It was negatively correlated with spermatozoa having reacted acrosome (r = −.654, p < .01). A fertility model built using a combination of sperm HBA and either sperm livability or viability predicts, respectively, 86.1% (r2 = .861, p < .01) and 85.9% (r2 = .859, p < .01) variability in buffalo bull fertility. In conclusion, sperm HBA may prove to be a single robust predictor of Nili-Ravi buffalo bull fertility.  相似文献   
3.
In recent years, research and development of geopolymers has gained significant interest in the fields of repairs and restoration. This paper investigates the application of a geopolymer as a repair material by implementation of high-calcium fly ash (FA) as a main precursor, activated by a sodium hydroxide and sodium silicate solution. Three methods of concrete substrate surface preparation were cast and patched: as-cast against ordinary Portland cement concrete (OPCC), with drilled holes, wire-brushed, and left as-cast against the OPCC grade 30. This study indicated that FA-based geopolymer repair materials (GRMs) possessed very high bonding strength at early stages and that the behavior was not affected significantly by high surface treatment roughness. In addition, the investigations using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy have revealed that the geopolymer repair material became chemically bonded to the OPC concrete substrate, due to the formation of a C–A–S–H gel. Fundamentally, the geopolymer network is composed of tetrahedral anions (SiO4)4− and (AlO4)5− sharing the oxygen, which requires positive ions such as Na+, K+, Li+, Ca2+, Na+, Ba2+, NH4+, and H3O+. The availability of calcium hydroxide (Ca(OH)2) at the surface of the OPCC substrate, which was rich in calcium ions (Ca2+), reacted with the geopolymer; this compensated the electron vacancies of the framework cavities at the bonding zone between the GRM and the OPCC substrate.  相似文献   
4.
While coronary artery bypass grafting remains an essential component of revascularization therapy, the use of venous conduits in the form of saphenous vein grafts is associated with a number of late sequelae, including graft stenosis and occlusion. The recognition of saphenous vein graft aneurysm, typically a late complication, may be associated with adverse outcomes. We describe the percutaneous therapy of saphenous vein graft aneurysm, utilizing contemporary devices, including newer generation covered stents, and the use of devices more commonly used in peripheral vascular intervention, reflecting the dilated nature of vein grafts. Saphenous vein graft aneurysm can be successfully treated with percutaneous therapy, avoiding the risk of repeat sternotomy and associated morbidity. The use of new generation covered stents has not been previously well reported; however, it may have an important role in the treatment of coronary artery and saphenous vein graft aneurysm. Awareness of the role of covered stents used in both coronary and peripheral intervention and the advantages of new generation devices are essential to allow optimal therapy of this uncommon, late complication. The role and potential benefits of new generation covered stents are discussed with a review of the existing literature.  相似文献   
5.
6.
7.
Glaucoma is a progressive and deteriorating optic neuropathy that leads to visual field defects. The damage occurs as glaucoma is irreversible, so early and timely diagnosis is of significant importance. The proposed system employs the convolution neural network (CNN) for automatic segmentation of the retinal layers. The inner limiting membrane (ILM) and retinal pigmented epithelium (RPE) are used to calculate cup-to-disc ratio (CDR) for glaucoma diagnosis. The proposed system uses structure tensors to extract candidate layer pixels, and a patch across each candidate layer pixel is extracted, which is classified using CNN. The proposed framework is based upon VGG-16 architecture for feature extraction and classification of retinal layer pixels. The output feature map is merged into SoftMax layer for classification and produces probability map for central pixel of each patch and decides whether it is ILM, RPE, or background pixels. Graph search theory refines the extracted layers by interpolating the missing points, and these extracted ILM and RPE are finally used to compute CDR value and diagnose glaucoma. The proposed system is validated using a local dataset of optical coherence tomography images from 196 patients, including normal and glaucoma subjects. The dataset contains manually annotated ILM and RPE layers; manually extracted patches for ILM, RPE, and background pixels; CDR values; and eventually final finding related to glaucoma. The proposed system is able to extract ILM and RPE with a small absolute mean error of 6.03 and 5.56, respectively, and it finds CDR value within average range of ± 0.09 as compared with glaucoma expert. The proposed system achieves average sensitivity, specificity, and accuracies of 94.6, 94.07, and 94.68, respectively.  相似文献   
8.
BACKGROUNDColorectal cancer (CRC) is the third leading cause of cancer-related death in males and females in the United States. Approximately, 20%-22% of patients have metastatic disease at the time of presentation, and 50%-60% will develop metastasis over the course of their disease. Despite advances in systemic therapies, there remains a paucity of effective third- and later-line therapies for patients with ongoing disease progression. However, rechallenging chemo-resistant CRC tumors with previously administered therapies is an emerging concept that may be a life-prolonging option for heavily treated metastatic colorectal cancer (mCRC).CASE SUMMARYA 41-year-old man with no previous medical history initially presented with worsening diffuse abdominal tenderness. Computed tomography was significant for a splenic flexure mass and hepatic lesions concerning for metastatic disease. He underwent a colectomy with anastomosis. Postoperative pathology was diagnostic for moderately to well-differentiated adenocarcinoma (T4bN1bM1a). He received adjuvant 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX), but therapy was discontinued due to the development of atrial fibrillation. Additional workup indicated a carcinoembryonic antigen level of 508.2 ng/mL, and mutational analysis found that the tumor was microsatellite instability-high and KRAS/BRAF wild-type. He was started on irinotecan with oxaliplatin (IROX), and bevacizumab (14 cycles), developed disease progression, was transitioned to FOLFOX and cetuximab, and then eventually three cycles of pembrolizumab. Following disease progression, he was rechallenged with IROX therapy, as he previously responded well to oxaliplatin-based therapy. The IROX rechallenge provided this patient with a ten-month survival benefit, decreased metastatic burden, and marked improvement in his clinical condition.CONCLUSIONRechallenge of previous lines of well-tolerated systemic chemotherapy regimens may be a valuable therapeutic strategy in patients with heavily-treated mCRC.  相似文献   
9.
10.
We report our experience in treating victims of the recent earthquake disaster in Pakistan. Our experience was based on two humanitarian missions to Islamabad: one in October 2005, 10 days after the earthquake, and the second in January 2006. The mission consisted of a team of orthopaedic surgeons and a second team of plastic surgeons. The orthopaedic team bought all the equipment for application of Ilizarov external fixators. We treated patients who had already received basic treatment in the region of the disaster and subsequently had been evacuated to Islamabad. During the first visit, we treated 12 injured limbs in 11 patients. Four of these patients were children. All cases consisted of complex multifragmentary fractures associated with severe crush injuries. All fractures involved the tibia, which were treated with Ilizarov external fixators. Nine fractures were type 3b open injuries. Eight were infected requiring debridement of infected bone and acute shortening. During a second visit, we reviewed all patients treated during our first mission. In addition, we treated 13 new patients with complex non-unions. Eight of these patients were deemed to be infected. All patients had previous treatment with monolateral fixators as well as soft tissue coverage procedures, except one patient who had had an IEF applied by another team. All these patients had revision surgery with circular frames. All patients from both groups were allowed to fully weight-bear post-operatively, after a short period of elevation to allow the flaps to take. Overall, all fractures united except one case who eventually had an amputation. Four patients had a corticotomy and lengthening, and three of them had a successful restoration of limb length. The fourth patient was the one with the eventual amputation.  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