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   13806篇
  免费   781篇
  国内免费   178篇
耳鼻咽喉   154篇
儿科学   336篇
妇产科学   378篇
基础医学   1874篇
口腔科学   315篇
临床医学   1406篇
内科学   2833篇
皮肤病学   524篇
神经病学   841篇
特种医学   666篇
外科学   2233篇
综合类   178篇
现状与发展   1篇
一般理论   2篇
预防医学   575篇
眼科学   284篇
药学   1132篇
中国医学   151篇
肿瘤学   882篇
  2023年   79篇
  2022年   194篇
  2021年   424篇
  2020年   202篇
  2019年   276篇
  2018年   413篇
  2017年   300篇
  2016年   350篇
  2015年   439篇
  2014年   646篇
  2013年   666篇
  2012年   1044篇
  2011年   1016篇
  2010年   608篇
  2009年   491篇
  2008年   809篇
  2007年   844篇
  2006年   743篇
  2005年   747篇
  2004年   643篇
  2003年   519篇
  2002年   496篇
  2001年   427篇
  2000年   395篇
  1999年   309篇
  1998年   142篇
  1997年   106篇
  1996年   108篇
  1995年   80篇
  1994年   72篇
  1993年   43篇
  1992年   130篇
  1991年   115篇
  1990年   108篇
  1989年   72篇
  1988年   63篇
  1987年   67篇
  1986年   54篇
  1985年   53篇
  1984年   35篇
  1983年   23篇
  1979年   31篇
  1977年   30篇
  1976年   25篇
  1975年   25篇
  1974年   28篇
  1973年   26篇
  1972年   30篇
  1970年   23篇
  1968年   22篇
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
21.
AIM: Benign childhood epilepsy with centro-temporal spikes (BCECTS) is the most common idiopathic partial epilepsy in children. Treatment attitudes remain a controversial issue. We examine features that could suggest refractoriness at onset. METHODS: We retrospectively reviewed the medical records of 144 children with BCECTS diagnosed at the Division of Pediatric Neurology, Asan Medical Center, from March 1, 1995, to April 30, 2002 and treated with AEDs. The patients were subdivided into two groups according to the number of antiepileptic drugs used for effective seizure control. RESULTS: Of the 144 patients, 75 were male and 69 were female, with a mean age at seizure-onset of 7.2 +/- 2.3 years (range, 2.1-14.3 years); 119 children were taking one antiepileptic drug (AED) (Group A), and 25 were taking more than one (Group B). There were no significant group differences in female-to-male ratio, prescribed AEDs, number of seizures before the start of treatment, interval between seizure-onset and start of treatment, presence of secondarily generalized seizures, or presence of bilateral EEG abnormalities. The groups differed however, in mean age at seizure onset (7.6 +/- 2.2 years versus 5.1 +/- 1.9 years, p < 0.05) and percentage of patients with seizure-onset before 3 years (p < 0.05). CONCLUSIONS: When treated with AEDs, children with BCECTS usually respond well. However, an earlier onset of seizures is associated with more frequent seizures and initial refractoriness to medical treatment.  相似文献   
22.
A lateral patella luxation is occasionally complicated by an (osteo)chondral fracture. These fractures are usually located at the inferomedial part of the patella. In this case report we describe an osteochondral fracture of the lateral femoral condyle after a dislocation of the patella. The latter is a more severe injury because it involves an important weight bearing part of the knee joint. Refixation of the osteochondral fracture should be pursued. Various surgical techniques using nonresorbable materials have been described. We describe the advantages and disadvantages of refixation with biodegradable pin fixation for an osteochondral fracture caused by a patellaluxation.  相似文献   
23.
Ryo Hattori  MD    Tateki Kubo  MD    Kenji Yano  MD  PhD    Atsushi Tanemura  MD    Yuji Yamaguchi  MD  PhD    Satoshi Itami  MD  PhD    Ko Hosokawa  MD  PhD 《Dermatologic surgery》2003,29(10):1071-1072
BACKGROUND: Nevus lipomatosus cutaneous superficialis (NLCS) is a relatively rare condition. Although NLCS can affect any region of the entire body, no case of NLCS in the clitoris has ever been reported. OBJECTIVE: To report a case of NLCS of the clitoris that presented manifestations that were similar to female pseudohermaphrodism. METHODS: This is a case report and review of the literature. RESULTS: A congenital, soft, skin-colored lesion of the clitoris in a 1-year-old girl resembled female pseudohermaphrodism. It was resected, and the histologic diagnosis was NLCS. Postoperatively, there was no subsequent change in the lesion during the 3-year follow-up period. CONCLUSION: We reported a case of congenital solitary NLCS of the clitoris. Although NLCS might be a relatively rare condition, we should consider it in the differential diagnosis of female pseudohermaphrodism.  相似文献   
24.
Aim: The prognosis of patients with disseminated colorectal carcinoma is poor except for those with single organ pulmonary or hepatic metastases. The objective of the present study was to evaluate the result of pulmonary metastasectomy for colorectal secondary and to identify the prognostic factors. Methods: This was a retrospective study of 80 patients who had pulmonary metastasectomy for pulmonary secondary from colorectal carcinoma in Queen Elizabeth Hospital, Hong Kong. Results: The overall 5‐year and 10‐year survival rates of the entire cohort were 42.5% and 35.5%, respectively. High premetastasectomy carcinoembryonic antigen (> 20 μg/dL), short disease‐free interval (< 12 months) and incomplete resection were the independent prognostic factors. Neither the characteristics of the primary colorectal tumour nor the number of metastatic nodules had a significant contribution to the long‐term survival. Six patients underwent second pulmonary metastasectomy and three were still free from tumour recurrence after the second operation. Conclusion: Patients with pulmonary metastases from colorectal carcinoma would benefit from pulmonary metastasectomy. High premetastasectomy carcinoembryonic antigen and short disease‐free interval were negative predictive factors for survival. Long‐term follow‐up study is required, as recurrence can occur more than 5 years after pulmonary metastasectomy. Also, whether the survival benefit is due to surgical treatment effect or lead‐time bias remains undecided.  相似文献   
25.
 To monitor the lead hazards in industries and to investigate the prevalence of elevated blood lead levels (BLLs) in lead-exposed workers, a lead surveillance system (PRESS-BLLs) has been established and operated in Taiwan, Republic of China, since July 1993. A cohort of lead-exposed workers who received a periodic annual health examination at 55 accredited hospital laboratories was constructed. A total of 9807 separate BLL measurements were reported to the system in 1994. The mean BLL was 15.8 μg/dl in male workers and 11.6 μg/dl in female workers. The mean BLL of lead-exposed workers was significantly (P<0.05, z-test) higher than that of the general Taiwanese population (8.6 μg/dl for males and 6.7 μg/dl for females). In addition, the BLLs of 983 (10.0%) workers exceeded the regulatory action level (40 μg/dl for males; 30 μg/dl for females). The workplaces and homes of 57% of the workers with elevated BLLs were thoroughly investigated to determine the sources of lead contamination. These actions identified the causes of elevated BLLs and set up strategies to reduce workers’ lead exposure. The establishment of this occupational lead surveillance system represents a method for monitoring of lead hazards from occupational and environmental settings to prevent lead poisoning. The information acquired from the system can help in the setting up of a priority of prevention and the development of control measures. It is also useful for further monitoring of changes in the BLLs of the lead-exposed-worker cohort. The Health Department of Taiwan can use this information to evaluate the effectiveness of current industrial hygiene practice. Subjects with elevated BLLs have been medically treated and placed on long-term follow-up for sequelae. Received: 2 September 1996/Accepted: 29 November 1996  相似文献   
26.
Implantation of porcine bone morphogenetic protein (pBMP) in the muscle induces differentiation of mesenchymal-type cells and results in endochondral bone formation. pBMP was isolated from porcine demineralized bone matrix and purified by hydroxyapatite chromatography, Sephadex G75 gel filtration, preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), preparative isoelectric focusing (IEF), and chromatofocusing fast protein liquid chromatography (FPLC). Porcine BMP has an MW of 26 K and a range of pI from 4.65 to 4.73 determined by SDS-PAGE and IEF, respectively. Reconstitution with the citrate buffer supernatant fraction enables as little as 50 micrograms of the soluble pBMP fractions to induce osteogenesis in an in vivo assay. Chemical modification studies indicate that the osteoinductive potential of the pBMP molecule depends on tyrosine, carboxyl groups, and disulfide bonds and can be increased by modification of sulfhydryl groups. Modification of arginine and tryptophan has no effect on bioactivity. By pepsin-limited proteolysis, fragments of pBMP with an MW of 6-14 K show definite, although reduced, BMP activity.  相似文献   
27.
T C Ko  M Flisak  R A Prinz 《Gastroenterology》1992,102(3):1062-1064
A 40-year-old woman had persistent Zollinger-Ellison syndrome despite excision of a 4-cm duodenal gastrinoma. Localizing studies including ultrasonography, computed tomography, magnetic resonance imaging, duodenal endoscopy, endoscopic ultrasonography, and intraoperative endoscopic transillumination of the duodenum failed to detect a tumor. Selective intra-arterial methylene blue injection was used to identify a 6-mm gastrinoma in the duodenum, which was locally excised. Postoperatively, the patient had a negative secretin provocative test result. This novel method uses selective arterial secretin injection with hepatic venous gastrin sampling to identify the vessel feeding the gastrinoma. An angiographic catheter is then positioned in this artery. At laparotomy, methylene blue is injected through this catheter to selectively stain the gastrinoma, facilitating its identification. Selective intra-arterial methylene blue injection can enhance intraoperative detection of small gastrinomas and may improve the rate of curative resection in the Zollinger-Ellison syndrome. Further evaluation of this novel localizing technique is warranted.  相似文献   
28.
1. Fifty-five intact and six baroreceptor denervated and vagotomized cats of either sex were anaesthetized intraperito-neally with urethane (400 mg/kg) and a-chloralose (40 mg/kg). Responses of the systemic arterial pressure (SAP), mean SAP (MSAP) and sympathetic vertebral nerve (VNA) and renal nerve activities (RNA) were recorded. 2. In intact animals, monosodium L-glutamate (Glu, 0.1 mol/L, 50 nL) was microinjected into pressor areas of the locus coeruleus (LC), gigantocellular tegmental field (GTF), rostral ventrolateral medulla (RVLM) and dorsomedial medulla (DM), and the depressor areas of caudal ventrolateral medulla (CVLM). The induced actions were compared before and after microinjection of either glutamate antagonists, glutamate diethylester (GDEE, 0.5 mol/L, 50–100nL), a competitive AMPA receptor blocker, or 2-amino-5-phosphonovaleric acid (D-AP5, 0.025 mol/L, 50–100 nL), a competitive N-methyl-D-aspartate (NMDA) receptor blocker. GDEE completely blocked the increases of SAP and VNA elicited from all pressor areas. D-AP5 only partially blocked the pressor but slightly blocked VNA and RNA responses from LC, GTF and DM, particularly those from RVLM. Neither GDEE nor D-AP5 blocked the depressor responses of SAP and two nerve activities elicited from CVLM. 3. In baroreceptor denervated animals, NMDA (2 mmol/L, 50–100 nL) and AMPA (0.2 mmol/L, 50–100 nL) were micro-injected into the same pressor areas of GTF, RVLM and DM and the depressor area of CVLM responsive to Glu activation (0.1 mol/L, 30 nL). In RVLM, DM and CVLM, the results of either NMDA or AMPA were similar to those induced by Glu. However, in GTF, microinjection of either NMDA or AMPA did not induce similar responses to Glu. This suggests that the nature of GTF may differ from RVLM and DM. 4. The above results suggest that the Glu-induced pressor responses from LC, GTF, DM and especially RVLM, are primarily mediated through AMPA receptors. The Glu-induced depressor responses from CVLM may not be predominantly mediated by either AMPA or NMDA receptors. 5. In both baroreceptor-intact and -denervated cats stimulation of the pressor areas often produced an increase of VNA and a decrease of RNA, while in the depressor CVLM decreased both VNA and RNA. The VNA, but not RNA were positively correlated with the pressor responses, while both VNA and RNA were positively correlated with the depressor responses. This may suggest that neurons of the sympathetic vertebral and renal nerves are topographically organized in the brain.  相似文献   
29.
Effects of posts on dentin stress distribution in pulpless teeth.   总被引:5,自引:0,他引:5  
A finite element analysis was carried out to study the roles of posts in reducing dentin stress in pulpless teeth. Two-dimensional plane strain models of the midlabiolingual section of a human maxillary central incisor were first analyzed. The results showed that the gold alloy post reduced maximal dentin stress by as much as 30%. However, the integrity of the dentin was compromised and the effects of the post were likely to be exaggerated in such models. In an effort to correct for these problems, plane stress models with side plates and axisymmetric models were analyzed. Posts were found to reduce maximal dentin stress by only 3% to 8% when the teeth were subjected to masticatory and traumatic loadings in these latter models. Although posts reduced maximal dentin stress by as much as 20% when the teeth were loaded vertically, teeth such as incisors and canines normally are not subjected to vertical loadings. Thus the reinforcement effects of posts seem to be doubtful in these teeth.  相似文献   
30.
To determine the genetic origin of the complete hydatidiform mole, 20 abnormal pregnancies were studied with restriction fragment length polymorphism with five genomic probes: EJ 6.6, beta-globin gene, 3'alpha-hypervariable region, J-Bir, and St14. In the 12 cases of molar pregnancy, pure paternal origin was proved in 11 cases, but both maternal and paternal inheritance were shown in only one case. In the cases with pure paternal origin, all of the restriction fragment length polymorphisms were homozygous, although those of the fathers were heterozygous at 15 loci. In the four cases that mimicked hydatidiform mole but were diagnosed as hydropic change of villi, both paternal and maternal inheritance were noted. In the four pregnancies with blighted ovum, both paternal and maternal inheritance were shown in three cases; and in one case with a balanced translocation between chromosomes 13 and 14, only paternal inheritance was noted. This study showed that most of the complete hydatidiform moles were caused by fertilization of an empty egg by a duplicated haploid sperm, but rare exceptions may exist.  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