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   6871篇
  免费   302篇
  国内免费   34篇
耳鼻咽喉   104篇
儿科学   140篇
妇产科学   83篇
基础医学   905篇
口腔科学   141篇
临床医学   372篇
内科学   1629篇
皮肤病学   223篇
神经病学   528篇
特种医学   257篇
外科学   1242篇
综合类   43篇
一般理论   1篇
预防医学   182篇
眼科学   142篇
药学   296篇
中国医学   11篇
肿瘤学   908篇
  2023年   28篇
  2022年   63篇
  2021年   123篇
  2020年   76篇
  2019年   88篇
  2018年   124篇
  2017年   103篇
  2016年   159篇
  2015年   181篇
  2014年   186篇
  2013年   281篇
  2012年   423篇
  2011年   479篇
  2010年   283篇
  2009年   205篇
  2008年   431篇
  2007年   427篇
  2006年   478篇
  2005年   472篇
  2004年   478篇
  2003年   496篇
  2002年   449篇
  2001年   71篇
  2000年   64篇
  1999年   89篇
  1998年   116篇
  1997年   117篇
  1996年   82篇
  1995年   81篇
  1994年   63篇
  1993年   55篇
  1992年   41篇
  1991年   43篇
  1990年   24篇
  1989年   30篇
  1988年   29篇
  1987年   22篇
  1986年   13篇
  1985年   16篇
  1984年   20篇
  1983年   19篇
  1982年   23篇
  1981年   26篇
  1980年   21篇
  1979年   16篇
  1978年   14篇
  1977年   8篇
  1976年   9篇
  1975年   11篇
  1971年   9篇
排序方式: 共有7207条查询结果,搜索用时 15 毫秒
91.
Pseudohypoparathyroidism type Ia (PHP-Ia), one of 4 types of PHP, is a genetic disease characterized by clinical hypoparathyroidism caused by parathyroid hormone (PTH) resistance. In addition, patients with PHP-Ia show resistance to other hormones as well as Albright's hereditary osteodystrophy (AHO), a constellation of features including short stature, obesity, brachydactyly, ectopic ossifications, and/or mental retardation. Hypocalcemia is one of the hallmarks of PHP-Ia, but several PHP-Ia patients have been described to have normocalcemia. We encountered a 10-year-old girl with typical Albright's hereditary osteodystrophy with round face, short stature, brachydactyly, and obesity. Biochemical examination showed normocalcemia and increased PTH levels. Ellsworth-Howard test did not show any responses of urinary cAMP and phosphate. Based on these findings, she was diagnosed as having PHP-Ia with normocalcemia. Sequencing analysis of the GNAS gene identified a heterozygous missense mutation in exon 13 (R385H), which was previously reported in a PHP-Ia patient. The exact reason for her normocalcemia is not determined, but we must recognize heterogeneous biochemical findings even in PHP-Ia.  相似文献   
92.
93.
94.
OBJECTIVES: We sought to describe clinical and laboratory findings for a large cohort of patients with thienopyridine-associated thrombotic thrombocytopenic purpura (TTP). BACKGROUND: The thienopyridine derivatives, ticlopidine and clopidogrel, are the 2 most common drugs associated with TTP in databases maintained by the U.S. Food and Drug Administration (FDA). METHODS: Clinical reports of TTP associated with clopidogrel and ticlopidine were identified from medical records, published case reports, and FDA case reports (n = 128). Duration of thienopyridine exposure, clinical and laboratory findings, and survival were recorded. ADAMTS13 activity (n = 39) and inhibitor (n = 30) were measured for a subset of individuals. RESULTS: Compared with clopidogrel-associated TTP cases (n = 35), ticlopidine-associated TTP cases (n = 93) were more likely to have received more than 2 weeks of drug (90% vs. 26%), to be severely thrombocytopenic (84% vs. 60%), and to have normal renal function (72% vs. 45%) (p < 0.01 for each). Compared with TTP patients with ADAMTS13 activity >15% (n = 13), TTP patients with severely deficient ADAMTS13 activity (n = 26) were more likely to have received ticlopidine (92.3% vs. 46.2%, p < 0.003). Among patients who developed TTP >2 weeks after thienopyridine, therapeutic plasma exchange (TPE) increased likelihood of survival (84% vs. 38%, p < 0.05). Among patients who developed TTP within 2 weeks of starting thienopyridines, survival was 77% with TPE and 78% without. CONCLUSIONS: Thrombotic thrombocytopenic purpura is a rare complication of thienopyridine treatment. This drug toxicity appears to occur by 2 different mechanistic pathways, characterized primarily by time of onset before versus after 2 weeks of thienopyridine administration. If TTP occurs after 2 weeks of ticlopidine or clopidogrel therapy, therapeutic plasma exchange must be promptly instituted to enhance likelihood of survival.  相似文献   
95.

Background/Purpose

Between 1988 and 2003, 38 patients underwent biliary resection for pancreaticobiliary maljunction (PBM). We reviewed the histopathologic findings for the surgically resected specimens to compare the clinical and pathologic features and assess the relationship between changes in the background biliary epithelium and the development of neoplasms.

Methods

Papillary hyperplasia (PHP) seen in the biliary epithelium of patients with PBM, was classified into grades 0–III in the gallbladder and grades 0–II in the extrahepatic bile duct, according to the extent, and was assessed for links with tumors in the same specimens.

Results

The incidence of gallbladder carcinoma was 13/21 in grades I–II, versus 0/16 in grade III, while the incidence of bile duct carcinoma was 4/20 in grade I versus 0/5 in grade II. Furthermore, these incidences for patients below age 50 years and age 50 or older were 1/18 versus 12/20, and 0/14 versus 6/17, respectively.

Conclusions

PHP of the biliary epithelium in PBM patients is an important precursor lesion, especially for gallbladder cancer, and the risk becomes greater with age, regardless of the type of pancreatobiliary junction (PBJ) and its location in the biliary tract.  相似文献   
96.
A chronic myeloproliferative disorder associated with monosomy 7 is described in a 3 1/2-year-old boy. His presenting features closely resembled those of juvenile chronic myeloid leukaemia (JCML). Cytogenetic study of bone marrow cells showed that all of the metaphases examined had chromosome 7 deletions. He developed an erythroblastic phase, characterized by anaemia, marked erythroid hyperplasia of bone marrow and the appearance of nucleated red blood cells in the peripheral blood. During the erythroblastic phase, blood transfusion resulted in a suppression of erythropoiesis as evidenced in both the peripheral blood and bone marrow. The in vitro culture studies showed that the erythroid precursor was dependent upon erythropoietin (Ep) for differentiation and proliferation during the erythroblastic phase. However, the Ep dose-response curve showed that a peak of erythroid colony formation occurred at a lower concentration than in the healthy controls. These findings suggest that although the erythroid precursor remains under the control of Ep, it has an increased sensitivity to Ep during the erythroblastic phase of monosomy 7.  相似文献   
97.
The new World Health Organization (WHO) classification of hematologic malignancies has incorporated t(8;21) myelodysplastic syndromes (MDS) according to the French-American-British classification into the category of acute myeloid leukemia (AML) with t(8;21)(q22;q22), while our knowledge about clinicopathological features of t(8;21) oligoblastic leukemia is still limited. We present our experience with 12 patients meeting the FAB diagnostic criteria of MDS and having t(8;21), who were compared to 43 t(8;21) AML patients. The MDS and AML patients shared most hematomorphologic, immunophenotypic, and clinical features, whereas the differences lay along myeloid maturation. The MDS patients had higher percentages of circulating neutrophils and marrow myeloid cells beyond promyelocytes than the AML patients. The incidence of Auer rods in mature neutrophils in MDS was significantly higher than that in AML, and furthermore, the neutrophils in MDS more commonly contain t(8;21) than in AML. Our findings support the rationale for the WHO classification, and future studies on large patient populations should help clarify whether the spontaneous differentiation potential could be actively associated with a hematological manifestation of t(8;21) leukemias.  相似文献   
98.
This study aimed to evaluate the clinical use of choline-PET/CT for discriminating viable progressive osteoblastic bone metastasis from benign osteoblastic change induced by the treatment effect and evaluating the response of bone metastasis to treatment in metastatic castration-resistant prostate cancer (mCRPC) patients. Thirty patients with mCRPC underwent a total of 56 11C-choline-PET/CT scans for restaging, because 4 patients received 1 scan and 26 had 2 scans. Using 2 (pre- and post-treatment) 11C-choline-PET/CT examinations per patient, treatment response was assessed according to European Organization for Research and Treatment of Cancer (EORTC) criteria in 20 situations, in which only bony metastases were observed on 11C-choline-PET/CT scans. Viable bone metastases and osteoblastic change induced by the treatment effect were identified in 53 (94.6%) and 29 (51.8%) of 56 11C-choline-PET/CT scans, respectively. In 27 cases (48.2%), 11C-choline-PET/CT scans could discriminate the 2 entities. The mean SUVmax of the metastatic bony lesions was 5.82 ± 3.21, 5.95 ± 3.96, 6.73 ± 5.04, and 7.91 ± 3.25 for the osteoblastic, osteolytic, mixed, and invisible types, respectively. Of the 20 situations analyzed, CMR, PMR, SMD, and PMD, as determined by the EORTC, were seen in 1, 2, 3, and 14 cases, respectively. Of the 13 patients with increasing PSA trend, all 13 showed PMD. Of the 2 patients with PSA response of <50%, both 2 showed SMD. Of the 5 patients with PSA response of ≥50%, 1 showed CMR, 2 showed PMR, 1 showed SMD, and 1 showed PMD. Choline-PET/CT is very useful to discriminate viable progressive osteoblastic bone metastasis from osteoblastic change, and assess treatment response of bone metastases in mCRPC.  相似文献   
99.
Primary pericardial sarcomas are very rare. A 62-year-old Japanese man presented with cardiac tamponade. Echocardiography, computed tomography and magnetic resonance imaging revealed massive pericardial effusion and a large tumor in the pericardial cavity, attached to the pericardium of the left ventricular posterolateral free wall. Surgical excision of the tumor was performed and histopathological and immunohistochemical examinations identified high-grade myofibroblastic sarcoma. Because of local recurrence soon after surgery, the patient received adjuvant chemotherapy, including doxorubicin and ifosfamide, and subsequent radiotherapy. As of 6 months after completing radiotherapy, the patient was alive and no disease progression or distant metastases were evident. This may be the first report of primary high-grade myofibroblastic sarcoma arising from the pericardium.  相似文献   
100.
We report on a Japanese boy with Noonan syndrome who had short stature, bilateral cryptorchidism, poor pubertal development, mild mental retardation, complex cardiac lesions consisting of hypertrophic cardiomyopathy, mitral valve stenosis and insufficiency, subvalvular aortic stenosis, and single coronary artery, and various dysmorphic features including hypertelorism, epicanthic folds, low set malrotated ears, high arched palate, micrognathia, webbed neck, low posterior hairline, shield chest, pectus excavatum, cubitus valgus, borderline short metatarsals, lymphedema, redundant skin, and nail dysplasia. Because of marked lymphedema in the bilateral lower legs, lymphatic scintigraphy was carried out at 13.3 years of age, indicating extreme lymphstasis in the lower extremities, severe lymphstasis in the forearm, the elbow, and the axillary regions, moderate lymphstasis around the ascending aorta, and mild lymphstasis in the bilateral lungs. The results, in conjunction with those suggested in Turner syndrome, imply that lymphatic hypoplasia/dysplasia and resultant distended lymphatics and lymphedema are relevant to the development of not only soft tissue and visceral anomalies but also skeletal anomalies in Noonan syndrome.  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