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   180412篇
  免费   1303篇
  国内免费   58篇
耳鼻咽喉   1271篇
儿科学   6662篇
妇产科学   3149篇
基础医学   17445篇
口腔科学   1624篇
临床医学   12753篇
内科学   31831篇
皮肤病学   924篇
神经病学   16718篇
特种医学   9208篇
外科学   29340篇
综合类   2344篇
一般理论   6篇
预防医学   18235篇
眼科学   2827篇
药学   9945篇
中国医学   716篇
肿瘤学   16775篇
  2023年   38篇
  2022年   95篇
  2021年   238篇
  2020年   131篇
  2019年   168篇
  2018年   22077篇
  2017年   17491篇
  2016年   19704篇
  2015年   1229篇
  2014年   1157篇
  2013年   1127篇
  2012年   7515篇
  2011年   21472篇
  2010年   19108篇
  2009年   11768篇
  2008年   19783篇
  2007年   21958篇
  2006年   770篇
  2005年   2383篇
  2004年   3482篇
  2003年   4448篇
  2002年   2564篇
  2001年   359篇
  2000年   478篇
  1999年   226篇
  1998年   225篇
  1997年   218篇
  1996年   111篇
  1995年   113篇
  1994年   109篇
  1993年   68篇
  1992年   62篇
  1991年   98篇
  1990年   128篇
  1989年   84篇
  1988年   58篇
  1987年   44篇
  1986年   31篇
  1985年   42篇
  1984年   30篇
  1983年   23篇
  1982年   25篇
  1980年   42篇
  1970年   24篇
  1969年   24篇
  1938年   60篇
  1937年   25篇
  1934年   30篇
  1932年   56篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Mammalian bones have three distinct origins (paraxial mesoderm, lateral plate mesoderm, and neural crest) and undergo two different modes of formation (intra-membranous and endochondral). Bones derived from the paraxial mesoderm and lateral plate mesoderm mainly form through the endochondral process. During this process, hypertrophic chondrocytes play a vital role in inducing both osteogenesis and angiogenesis. One of the essential osteogenic factors secreted from hypertrophic chondrocytes is Indian hedgehog (Ihh). In contrast, bones derived from the neural crest mainly form through the intramembranous pro-cess and do not require Ihh. Thus, depending on their origin, bones have distinct signaling properties, which need to be considered in the research and application of bone biology.Presented at the 18th Annual Research Meeting of the Japanese Orthopaedic Association, Kitakyushu, Japan, October 17, 2003  相似文献   
132.
133.
Background Application of linear stapling devices for extrahepatic vascular control in liver surgery has been well-established. However, the technique for use of stapling devices in hepatic parenchymal transection is not well defined. Purpose To describe the safety and efficacy of our technique for use of vascular stapling devices in hepatic parenchymal transection during open right hepatic lobectomy is the purpose of this study. Methodology We reviewed our experience with 101 consecutive open right hepatic lobectomies performed by a single surgeon between January 2003 and July 2006, in which vascular staplers were utilized for the parenchymal transection phase. Results Of the 101 patients who underwent resection, 53 (52%) were female. The mean age was 58 years. Malignant disease was the indication for resection in the majority of patients (88%). Of those with cancer, 78% (69 of 89) had metastatic colorectal cancer, 6% (5 of 89) had metastatic neuroendocrine tumor, 4% (4 of 89) had hepatocellular carcinoma, 4% (4 of 89) had cholangiocarcinoma, and the remaining 8% were other metastatic cancers. Twelve patients (12%) underwent resection for hepatic adenoma or symptomatic benign disease (FNH or hemangioma). Forty-eight patients (48%) underwent a major ancillary procedure at the time of hepatic resection. Thirty-nine patients (39%) had a nonanatomic wedge resection of a left lobe lesion, 27 patients (27%) had one or more lesions treated with radiofrequency ablation (RFA), and 6 patients (6%) were treated with a synchronous bowel resection. The median total operative time was 336 min (range 155–620 min). A Pringle maneuver for temporary vascular inflow occlusion was utilized in all cases, with a median time of 9 min (range 4–17 min). Ten patients (10%) required blood transfusion during surgery or in the postoperative period. The maximum transfusion was 2 U of packed red blood cells (PRBC) in seven patients and 1 U of PRBC in three patients. The mean nadir postoperative hematocrit was 28.2. All patients with malignant disease had tumor-free margins at the completion of the procedure. The average hospital length of stay was 6.0 days. One patient (1%) developed a clinically significant bile leak requiring a postoperative endoscopic retrograde cholangiography (ERCP). No patient required reoperation. The 30 and 60-day postoperative survival was 100%. Conclusion These findings indicate that application of vascular stapling devices for parenchymal transection in major hepatic resection is a safe technique, with low transfusion requirements and minimal postoperative bile leak. The technique allows for rapid transection of the entire right hepatic lobe in under 10 min. Short video clips of the technique will be demonstrated. Presented at the 2007 American Hepato–Pancreato–Biliary Association, Las Vegas, Nevada, April 19–22, 2007 (oral presentation/video presentation).  相似文献   
134.
Object A radiation dose of 40–50 Gy is able to produce a cure rate of more than 90% in intracranial pure germinoma. However, many attempts have been made to reduce the dose and volume of radiation without compromising the disease control rate because of the toxicity of irradiation. This retrospective study is intended to provide the physician with an appropriate therapeutic strategy. Materials and methods We reviewed a series of 10 recurrent germinomas among 117 germinomas diagnosed histologically or clinically between 1979 and 2002. These patients involved underwent three different treatment modalities; radiation alone (N = 71), chemotherapy alone (N = 9), and combined therapy (N = 37). The 10-year overall and relapse-free survival rates were 97 and 93% in the radiation alone group, 89 and 67% in the chemotherapy alone group, and 92 and 92% in the combined therapy group, respectively. As expected, both radiation therapy and combined therapy were effective in controlling the disease. Tumor recurrence was closely related to the volume of radiation but not to the dose of radiation. If the tumor bed and craniospinal axis were fully covered, the radiation dose might be reduced. Chemotherapy alone showed earlier recurrence and a higher tumor recurrence rate. In the case of combined therapy, chemotherapy was useful in reducing the radiation dose but revealed some toxicity (death of two patients). Conclusions The investigation of a possible further dose reduction seems worthwhile. Radiation therapy alone with a dose of less than 40 Gy should be compared with ongoing chemotherapeutic protocols combined with low-dose irradiation.  相似文献   
135.
Conclusion  Quantification of nuclear cardiac images provides a secondary support in reading myocardial perfusion images and improves the reproducibility in the diagnosis of cardiovascular diseases. The technology for the remote Web reading of nuclear cardiac images and the quantitative data allows for an easy and secured access to patient studies without the limitations of time and space. The recent increasing interests and applications in molecular targeted imaging have opened a new field in nuclear cardiology, and absolute image quantification of the focal tracer uptake in the myocardium is exceedingly critical for the quantitative analysis of molecular targeted images.  相似文献   
136.
CASE REPORT: A 12-year-old boy who had a history of Kawasaki disease 9 years ago experienced a subarachnoid hemorrhage by ruptured right posterior cerebral artery aneurysm. On day 1 operation, as the aneurysm was very fragile and bled easily, two intraoperative ruptures, including a very premature rupture, were encountered. As a result, a left hemiparesis especially severe in the left hand was caused by the right anterior thalamic infarction due to the occlusion of a thalamo-perforating artery arising near the neck of the aneurysm. DISCUSSION: The histopathological examination of the intraoperative excised aneurysmal dome disclosed the thickening of the endothelial inner due to the endothelial hypertrophy and the invasion of inflammatory cells. This finding of the aneurysm was partially mimicking the finding of the coronary artery of the patients with Kawasaki disease. The combination of cerebral aneurysm and Kawasaki disease has never been reported until now, and the etiology of the aneurysm of this patient is unclear.  相似文献   
137.
Febrifugine and isofebrifugine alkaloid mixtures extracted from the leaves and buds of Hydrangea macrophylla var. Otaksa, collected during different months, in Japan, were quantified using high-performance liquid chromatography. Leaves collected during the flowering season, namely from June to August, contained 0.16–0.31 mg/g of the alkaloid mixture, whereas those collected from September to December had less than 0.03 mg/g of the mixture. However, extracts of buds harvested from October to February contained a consistently larger amount (more than 0.49 mg/g) of the alkaloids. Hot-water extracts from the leaves and buds collected during different seasons were evaluated for antimalarial activity against Plasmodium yoelii 17XL in mice. The extract of leaves collected in August demonstrated high antimalarial activity, and all mice that received the extract survived the infection. In contrast, the extract of leaves collected in December showed little activity. The extract of buds collected in December cleared parasites, but with subsequent mortality to mouse. The present results show that the amount of antimalarial agent—febrifugine and isofebrifugine mixture—in H. macrophylla var. Otaksa is both part- and season-dependent, suggesting that the choice of plant parts and their harvesting season are important factors worth considering in the pharmacological use of medicinal plants.  相似文献   
138.

Background  

The telomeric region of mouse chromosome 12 has previously shown frequent allelic loss in murine lymphoma. The Bcl11b gene has been identified and suggested as a candidate tumor suppressor gene within this region. In this study, we aimed to elucidate whether Bcl11b is mutated in lymphomas with allelic loss, and whether the mutations we detected conferred any effect on cell proliferation and apoptosis.  相似文献   
139.
140.
Abstract 10 embalmed cadaver forearms and wrists were dissected to determine the anatomical course of the superficial branch of the radial nerve in the distal forearm. The superficial radial nerve bifurcated in two branches at a mean of 54,7 mm proximal to the radial styloid. From the styloid process of the radius, the mean distance to the closest dorsal branch of the superficial radial nerve was 3,5 mm and the mean distance to the closest volar branch was 9,8 mm. The mean distance between the closest branch of the superficial radial nerve and Lister?s tubercle was 16,4 mm. The crossing point between the nerve and the cephalic vein was located at a mean of 54,3 mm proximal to the styloid process. At the level of styloid process the mean distance between the closest dorsal branch of the superficial radial nerve and the first dorsal compartment was 15,2 mm and between the closest volar branch and the first dorsal compartment 4,4 mm. Detailed knowledge of anatomic characteristics of the superficial branch of the radial nerve may help prevent injury during operations and treat traumatic lesions of the nerve. Because of great variations in the course of the superficial radial nerve we could not define an absolute safe zone for surgical procedures on the distal forearm. Iatrogenic lesions of the superficial radial nerve are described complications of percutaneous procedures. Therefore open surgical approaches are recommended. Daniela Klitscher and Lars Peter Müller contributed equally to this work.  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