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   14010篇
  免费   1191篇
  国内免费   495篇
耳鼻咽喉   169篇
儿科学   95篇
妇产科学   37篇
基础医学   410篇
口腔科学   136篇
临床医学   1664篇
内科学   5752篇
皮肤病学   55篇
神经病学   333篇
特种医学   785篇
外国民族医学   1篇
外科学   2273篇
综合类   2197篇
现状与发展   1篇
预防医学   283篇
眼科学   33篇
药学   904篇
  15篇
中国医学   337篇
肿瘤学   216篇
  2024年   33篇
  2023年   324篇
  2022年   486篇
  2021年   884篇
  2020年   749篇
  2019年   640篇
  2018年   659篇
  2017年   529篇
  2016年   592篇
  2015年   615篇
  2014年   1074篇
  2013年   1063篇
  2012年   963篇
  2011年   988篇
  2010年   801篇
  2009年   712篇
  2008年   664篇
  2007年   688篇
  2006年   532篇
  2005年   420篇
  2004年   330篇
  2003年   254篇
  2002年   226篇
  2001年   178篇
  2000年   154篇
  1999年   157篇
  1998年   134篇
  1997年   111篇
  1996年   96篇
  1995年   88篇
  1994年   89篇
  1993年   63篇
  1992年   56篇
  1991年   51篇
  1990年   42篇
  1989年   34篇
  1988年   36篇
  1987年   26篇
  1986年   22篇
  1985年   31篇
  1984年   20篇
  1983年   11篇
  1982年   20篇
  1981年   8篇
  1980年   7篇
  1979年   6篇
  1978年   8篇
  1977年   4篇
  1976年   4篇
  1975年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We want to report on our experiences with the percutaneous trephination using a 2.35 mm round dental drill with serrated saws around it, a Rosenbohrer. It is a methodically similar activity as described by J. Zentner [11].From 1981 to 1992 519 patients were treated and 546 trephinations were performed.At the beginning this treatment was only used in connection with intracerebral bleedings and biopsies.In a considerable short time the indication could be extended to the subdural hematoma, tumor cyst, obstructive hydrocephalus as well as to the abscess and the subdural epyema.The rate of infection was 1.28% and the risk of bleeding 0.36%.In our opinion the advantages of this small electrical trephination are the easy handling, the universal use and mobility and the avoidable risk of anesthesia as well as the sterilisation at the same time and the stopping of blood, caused by the contact surface friction.  相似文献   
102.
The incidence and clinicopathologic features of unilateral multicentric breast cancer (UMBC) were studied by mammary gland serial sectioning in 116 cases of clinically defined monocentric breast cancer (MONBC) examined histopathologically at the Nagano Cancer Detection Center. UMBC was defined as: 1) histopathologically discontinuous tumors each with an intraductal spread, 2) at least one tumor-free section separating two tumors, and 3) a large primary tumor and other small secondary tumors. UMBC was detected in 23 of 116 cases (19.8%), all with one secondary tumor. Primary and secondary tumors were located in the same quadrant in 34.8% and in different ones in 65.2%. The secondary tumors were <5 mm in size in 56.5%. Secondary tumors, averaging 8.3 mm in size and 25.5 mm in distance from the primary tumor, were almost exclusively noninvasive carcinomas, including 15 (65.4%) noninvasive ductal carcinomas and several special types. The primary and secondary tumors were of the same histologic type in 3 of 23 cases. UMBC patients averaged 6 years younger than MONBC patients, and the incidence of UMBC tended to be higher in younger patients (p<0.1). UMBC tended to occur more frequently in quadrant with an average histologie tumor size significantly smaller than that in MONBC (p<0.01). The histologie types of the primary tumor in UMBC and MONBC were similar, with common types predominant. Lymph node metastases tended to be slightly more frequent in MONBC. This high incidence of UMBC calls for careful attention when considering breast conserving therapy.  相似文献   
103.
The cerebral representation of space depends on the integration of many different sensory inputs. The vestibular system provides one such input and its dysfunction can cause profound spatial disorientation. Using positron emission tomography (PET), we measured regional cerebral perfusion with various vestibular stimulations to map central vestibular projections and to investigate the cerebral basis of spatial disorientation. We showed that the temporoparietal cortex, the insula, the putamen, and the anterior cingulate cortex are the cerebral projections of the vestibular system in man and that the spatial disorientation caused by unilateral vestibular stimulation is associated with their asymmetric activation.  相似文献   
104.
Summary  The authors report a series of 13 patients with osteoporotic vertebral fractures treated by transpedicular vertebroplasty. Because of a neurological complication due to posterior leakage of acrylic cement the classical percutaneous approach was converted to an open surgical procedure. The latter allows direct visual control of neural structures and immediate removal of spilled cement, thus eliminating the danger of compressive, chemical and thermal effects of methyl methacrylate on neural elements.  By use of this elegant technique primary stability of fractured vertebras is obtained leading to prompt pain relief in all patients. Surgically controlled vertebroplasty can be used in conjunction with internal fixation. By having studied the different ways of cement escape in their patients, the authors are convinced that surgically controlled vertebroplasty is safer than percutaneous vertebroplasty.  相似文献   
105.
We describe herein the case of a 51-year-old woman in whom metastatic tumor seeding of the percutaneous transhepatic biliary drainage tract occurred following a pancreatoduodenectomy for carcinoma of the distal common bile, duct. An abdominal computed tomography scan done 6 months after the initial operation detected a hepatic lesion located at the site of the previous percutaneous transhepatic biliary drainage tract. Implantation of bile duct carcinoma in the drainage tract was diagnosed, and the recurrent tumor was successfully resected by performing a subsegmentectomy of segment 3 and removal of the adjacent abdominal wall. At present, 5 years and 4 months after the second resection, the patient is in good health without any signs of recurrence. This case report demonstrates that an aggressive surgical approach should be performed for tumor seeding of a transhepatic biliary catheter tract.  相似文献   
106.
This case study reports the progress of a 41-year-old man with advanced Huntington's disease (HD) during a 12-week period when he was fed a high-energy regimen via percutaneous endoscopic gastrostomy (PEG). The regimen consisted of a low-protein, low-mineral, energy-dense (2 kcal mL?1) carbohydrate polymer. Achieving weight gain with a 1.5 kcal mL?1 feed and carbohydrate polymer had produced steady but slow results (52–56 kg – a rise of 4 kg in 15 months). It was concluded that a more energy-dense regimen would facilitate faster weight gain.  相似文献   
107.
We herein report the usefulness of ultrasoundguided percutaneous needle biopsy for histological diagnosis in 18 patients with mediastinal tumors. Computed tomography revealed these tumors to be in contact with the chest wall. The preoperative diagnosis was thymoma in 7 patients, germinoma in 5, neurogenic tumor in 3, and other in 3. The most commonly encountered indication for an ultrasound-guided percutaneous needle biopsy was an anterior mediastinal lesion (78%; 14 of 18 patients). In 16 (89%) of the 18 patients, the biopsy diagnosis corresponded to the post-operative diagnosis. No complications were encountered in any of the patients. This new technique of ultrasound-guided percutaneous needle biopsy is both relatively simple and highly accurate and may thus be useful for outpatients. Preoperative ultrasound-guided percutaneous needle biopsy is thus considered to be a safe and reliable method for the histological diagnosis of mediastinal tumors, and a good alternative to traditional biopsy techniques such as mediastinoscopy or thoracotomy.Presented at the 11th Biennial Asian Congress on Thoracic and Cardiovascular Surgery, Kuala Lumpur, Malaysia, November, 21–25, 1993.  相似文献   
108.
The iontophoresis of eight tripeptides, of the general structure alanine–X–alanine, has been measured across hairless mouse skin in vitro. The peptides were blocked (a) at the carboxyl terminus using the mixed anhydride reaction with t-butylamine and (b) at the amino terminus by acetylation with 14C-acetic anhydride. The nature of the central residue (X) was varied by selecting one of five neutral amino acids, two negatively chargeable moieties (aspartic and glutamic acids), and a positively chargeable species (histidine). Constant current iontophoresis at 0.36 mA/cm2, using Ag/AgCl electrodes, was performed for 24 hr in diffusion cells, which allowed both anode and cathode to be situated on the same (epidermal) side of a single piece of skin. Due to a combination of osmotic and electroosmotic forces, the anodal iontophoretic flux of neutral peptides was significantly greater than passive transport. Steady-state fluxes were not achieved, however, suggesting that time-dependent changes in the properties of the skin barrier may be occurring. Limited, further experiments confirmed that, on a 24-hr time scale, these changes were not fully reversible. The cathodal delivery of anionic permeants was well controlled at a steady and highly enhanced rate by the current flow. This behavior closely paralleled earlier work using simple negatively charged amino acids and N-acetylated amino acid derivatives. It appears that the normalized iontophoretic flux of these anionic species is independent of lipophilicity but may be inversely related to molecular weight. The positively charged peptide, Ac–Ala–His–Ala–NH(But), showed greater anodal iontophoretic enhancement when delivered from a donor solution at pH 4.0 than from a solution at pH 7.4. This was consistent with (a) the corresponding behavior of histidine alone and (b) the existence of a pK a for these compounds at 6. Steady-state delivery was not achieved, although the levels of enhancement, especially at pH 4, were the largest observed. A preliminary investigation of tripeptide stability to either (i) electrolysis in the donor compartment or (ii) cutaneous metabolism revealed very little degradation under the conditions of the experiment. Overall, this research supports the principle of enhanced peptide delivery across the skin by iontophoresis and indicates a number of areas (e.g., mechanism and extent of current-induced changes in skin barrier function, molecular size dependence, pathways of current flow) on which further work should be focused.  相似文献   
109.
We report a patient with hemiparkinsonism associated with unilateral striatal necrosis of the contralateral side. The patient was an 18-year-old woman who had a two-month-history of difficulty in executing skilled movements with her right upper extremity. Neurological examination revealed that she had cogwheel rigidity and bradykinesia in her right upper and lower extremities. MRI revealed a well-delineated low signal intensity in T1-weighted and high signal intensity in T2-weighted images in the region of the putamen on the left side. Her laboratory data were unremarkable and mitochondrial gene mutation studies revealed no abnormality. It is extremely rare to encounter a case of parkinsonism associated with unilateral striatal necrosis.  相似文献   
110.
中药透皮吸收促进剂的研究与发展   总被引:18,自引:0,他引:18  
方晓阳  叶青 《中草药》2003,34(2):188-192
中药以其自身独特的优势倍受药学界的关注,中药透皮吸收促进剂已成为经皮给药研究的热点之一。研究较多的中药透皮吸收促进剂有薄荷醇、冰片、精油类等多种中药提取物,应用中可单独作用,也可与化学透皮吸收促进剂联合使用。对中药促透机制的研究也是当前药学界的热点之一。在概述这些研究成果的基础上,就中药透皮吸收促进剂的开发提出一些思路。  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