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   3736篇
  免费   180篇
  国内免费   69篇
耳鼻咽喉   76篇
儿科学   66篇
妇产科学   153篇
基础医学   614篇
口腔科学   82篇
临床医学   311篇
内科学   612篇
皮肤病学   102篇
神经病学   223篇
特种医学   155篇
外科学   620篇
综合类   113篇
预防医学   158篇
眼科学   60篇
药学   367篇
中国医学   33篇
肿瘤学   240篇
  2023年   27篇
  2022年   40篇
  2021年   94篇
  2020年   58篇
  2019年   68篇
  2018年   92篇
  2017年   83篇
  2016年   98篇
  2015年   144篇
  2014年   168篇
  2013年   166篇
  2012年   261篇
  2011年   264篇
  2010年   161篇
  2009年   117篇
  2008年   188篇
  2007年   205篇
  2006年   199篇
  2005年   169篇
  2004年   144篇
  2003年   120篇
  2002年   113篇
  2001年   106篇
  2000年   94篇
  1999年   89篇
  1998年   36篇
  1997年   27篇
  1996年   44篇
  1995年   34篇
  1994年   24篇
  1993年   19篇
  1992年   35篇
  1991年   44篇
  1990年   38篇
  1989年   41篇
  1988年   21篇
  1987年   25篇
  1986年   23篇
  1985年   33篇
  1984年   20篇
  1983年   14篇
  1979年   16篇
  1978年   21篇
  1977年   14篇
  1976年   13篇
  1975年   17篇
  1974年   17篇
  1973年   14篇
  1972年   18篇
  1966年   16篇
排序方式: 共有3985条查询结果,搜索用时 15 毫秒
11.
Accurate assessment and replacement of blood loss and fluid–electrolyte deficit during craniosynostosis repair is difficult owing to patient size and the diversity of surgical technique. Forty-three patients undergoing primary craniosynostosis repair over a 10-year period were studied retrospectively to determine blood loss and fluid deficit and to assess blood transfusion practices during both intraoperative and postoperative periods. Blood loss was calculated on the basis of estimated red cell mass (ERCM) and fluid-electrolyte imbalance was investigated with blood samplings. Blood transfusion was considered appropriate if the postoperative or posttransfusion ERCM was within 12% of the preoperative value. Estimated fluid requirement (EFR) was used in 4 ml kg–1 h–1 except for neonates. Intraoperatively, 80% of all patients were appropriately managed with respect to blood transfusion and EFR. Postoperatively only 20% of the patients receiving transfusions were transfused appropriately. In 23.3% of these patients (10/43) unexpected respiratory distress developed immediately after their recovery from the anesthesia. With the measurement of estimated blood volume and allowable blood loss, appropriate transfusion could be achieved for the successful treatment of the primary craniosynostosis. Received: 16 February 1998  相似文献   
12.
13.
We evaluated the relative contribution of plain radiographs and computed tomography to the assessment of fracture healing under experimental circumstances. In 15 sheep, we performed midshaft femoral osteotomies and internal fixation of the resultant segmental fractures. Radiographs were obtained preoperatively and immediately postoperatively. Animals were sacrificed at 3 weeks, 6 weeks, 12 weeks, 24 weeks, and 36 weeks after surgery, and the femoral specimens radiographed. After removal of the internal fixation devices, computed tomographic scans of the specimens were performed.By 3 weeks, callus was visible, but at 6 weeks, a trabecular pattern in the callus was seen on plain films but not on computed tomography. There was progressive organization of the callus on both studies. At 24 weeks, computed tomography demonstrated fracture lines not seen due to overlying callus on plain films and also more accurately showed incomplete union. By 36 weeks, healing was essentially complete according to both modalities, although there still were small gaps in the callus detectable on computed tomography but not on plain films.Computed tomography may be of value in the evaluation of fractures of long bones in those cases in which clinical examination and plain radiographs fail to give adequate information as to the status of healing.  相似文献   
14.
15.
16.
Acute transverse myelitis is a rare clinical manifestation of Coxsackie virus infection which cause acute and progressive debilitating illness associated with loss of spinal cord function in the affected patients. A 62 year-old female developed symptoms of rapidly progressive paraplegia with sensory loss. On spinal MRI, T2 sagittal image showed increased signal intensity with cord swelling at T11-L2 level and 8 folds or greater rise of Coxsackie virus B4 neutralizing antibody titers was observed in the CSF. There is only one previous report of acute transverse myelitis caused by Coxsackie virus B4 infection to our knowledge. The presence of specific viral antibody titers change in the CSF and a corresponding spinal cord lesion are sufficient to suggest a causal relationship between the virus and the illness. This article is a case report of an unusual acute transverse myelitis caused by Coxsackie virus B4 infection.  相似文献   
17.
The results of treating 12 consecutive patients with unresectable colorectal hepatic metastases with a hepatic arterial infusion of high-dose Adriamycin, 100–120 mg/m2, using hepatic venous isolation (HVI) and charcoal hemoperfusion (CHP) are reported herein. Adriamycin was administered over 5–15 min under extracorporeal drug elimination by HVI-CHP. HVI was percutaneously accomplished by either the double-balloon technique using a Fogarty occlusion catheter (8/22F) or a balloon-tipped catheter (16F). During the infusion, isolated hepatic venous blood was filtered by CHP and pumped into the left axillary vein. There were no lethal complications, and good hemodynamic tolerance to HVI-CHP was confirmed. Tumor liquefaction accompanied by a sharp decrease in serum carcinoembryonic antigen levels by more than 50% of pretreatment levels was observed in 6 of the 12 patients 1 month after treatment. Apart from chemical hepatitis, which developed in 11 (92%) of the patients, the Adriamycin toxicities were well controlled following the development of nausea and vomiting in 2 patients (17%), leukopenia <2,000/mm3 in 3 (25%), and gastric ulcer in 1 (8%). These results indicate that this method is a safe and useful procedure for otherwise hazardous high-dose intraarterial chemotherapy in patients with unresectable hepatic tumors.  相似文献   
18.
Multiple-bandwidth photoacoustic tomography   总被引:3,自引:0,他引:3  
Photoacoustic tomography, also referred to as optoacoustic tomography, employs short laser pulses to generate ultrasonic waves in biological tissues. The reconstructed images can be characterized by the convolution of the structure of samples, the laser pulse and the impulse response of the ultrasonic transducer used for detection. Although the laser-induced ultrasonic waves cover a wide spectral range, a single transducer can receive only part of the spectrum because of its limited bandwidth. To systematically analyse this problem, we constructed a photoacoustic tomographic system that uses multiple ultrasonic transducers simultaneously, each at a different central frequency. The photoacoustic images associated with the different transducers were compared and analysed. The system was tested by imaging both mouse brains and phantom samples. The vascular vessels in the brain were revealed by all of the transducers, but the image resolutions differed. The higher frequency detectors provided better image resolution while the lower frequency detectors delineated the major structural traits with a higher signal-noise ratio.  相似文献   
19.
Committing embryonic stem cells to early endocrine pancreas in vitro   总被引:12,自引:0,他引:12  
A panel of genetic markers was used to assess the in vitro commitment of murine embryonic stem (ES) cells toward the endoderm-derived pancreas and to distinguish insulin-expressing cells of this lineage from other lineages such as neuron, liver, and yolk sac. There are two nonallelic insulin genes in mice. Neuronal cells express only insulin II, whereas the pancreas expresses both insulin I and II. Yolk sac and fetal liver express predominately insulin II, small amounts of insulin I, and no glucagon. We found that ES-derived embryoid bodies cultured in the presence of stage-specific concentrations of monothio-glycerol and 15% fetal calf serum, followed by serum-free conditions, give rise to a population that expresses insulin I, insulin II, pdx-1 (a pancreas marker), and Sox17 (an endoderm marker). Immunohistochemical staining shows intracellular insulin particles, and its de novo production was confirmed by staining for C-peptide. Most, but not all, of the insulin+ or C-peptide+ cells coexpress glucagon, demonstrating a differentiation pathway to pancreas rather than yolk sac or fetal liver. Addition of beta-cell specification and differentiation factors activin beta B, nicotinamide, and exendin-4 to later-stage culture increased insulin-positive cells to 2.73% of the total population, compared with the control culture, which gave rise to less than 1% insulin-staining cells. These findings suggest that stepwise culture manipulations can direct ES cells to become early endocrine pancreas.  相似文献   
20.
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