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   5504篇
  免费   235篇
  国内免费   44篇
耳鼻咽喉   59篇
儿科学   132篇
妇产科学   78篇
基础医学   668篇
口腔科学   118篇
临床医学   331篇
内科学   1669篇
皮肤病学   86篇
神经病学   325篇
特种医学   155篇
外科学   777篇
综合类   23篇
一般理论   1篇
预防医学   141篇
眼科学   32篇
药学   483篇
中国医学   22篇
肿瘤学   683篇
  2023年   27篇
  2022年   47篇
  2021年   88篇
  2020年   58篇
  2019年   69篇
  2018年   57篇
  2017年   57篇
  2016年   85篇
  2015年   91篇
  2014年   137篇
  2013年   143篇
  2012年   249篇
  2011年   300篇
  2010年   173篇
  2009年   150篇
  2008年   274篇
  2007年   324篇
  2006年   308篇
  2005年   320篇
  2004年   326篇
  2003年   300篇
  2002年   335篇
  2001年   130篇
  2000年   160篇
  1999年   179篇
  1998年   85篇
  1997年   65篇
  1996年   61篇
  1995年   52篇
  1994年   39篇
  1993年   62篇
  1992年   119篇
  1991年   75篇
  1990年   79篇
  1989年   90篇
  1988年   81篇
  1987年   74篇
  1986年   41篇
  1985年   61篇
  1984年   46篇
  1983年   45篇
  1982年   22篇
  1981年   19篇
  1979年   44篇
  1978年   18篇
  1975年   20篇
  1973年   18篇
  1972年   18篇
  1969年   20篇
  1968年   21篇
排序方式: 共有5783条查询结果,搜索用时 46 毫秒
11.
A 80-year old man was referred to our hospital because of an elevation of serum amylase level. Diffuse enlargement of the pancreas was detected by abdominal computed tomography, and also diffuse narrowing of the main pancreatic duct was revealed using endoscopic retrograde cholangiopancreatography. The serum level of IgG was elevated to 3450mg/dl. Besides, on the 10th hospital day, petechia developed and the platelet level decreased to 1.5 x 10(4)/microl. The platelet-associated IgG, antiplatelet antibody and antinuclear antibody in serum were positive. The levels of serum complements were low. From all these findings the patient was diagnosed as autoimmune pancreatitis complicated with immune thrombocytopenia. The treatment with prednisolone was started, which was effective on each disease. The medication was suspended a year ago, and so far there is no data suggesting the recurrence of autoimmune pancreatitis or immune thrombocytopenia.  相似文献   
12.
Gastric cancer heterogeneity   总被引:1,自引:0,他引:1  
This study was carried out on 222 samples from 37 gastric carcinomas to assess the incidence of multiple stem lines in primary tumors and metastasis as reflected by multiple DNA stem lines and their relationship to epidermal growth factor (EGF) receptor expression, histologic grade, tumor size, and degree of wall infiltration. Fifteen primary tumors (40.5%) were homogeneously diploid/peridiploid whereas 22 (59.5%) were aneuploid. In the lymph node metastasis, seven patients (29.2%) had an homogeneous diploid/peridiploid pattern in all metastatic lymph nodes. On the other hand, 17 (70.8%) had at least one aneuploid peak in the lymph node metastasis. DNA content heterogeneity was seen in 12 (33%) of primary tumors whereas 14 (66.6%) of 21 patients had multiple cell clones in the metastasis. Therefore, 12 patients had a metastatic clone which was not observed in the primary tumor. DNA content heterogeneity was seen even in tumors with submucosal invasion suggesting that this phenomenon is also present at earlier stages. No correlation between the histologic grade and the DNA distribution was observed. Furthermore, histologic heterogeneity was independent of DNA content heterogeneity. The EGF receptor expression was observed in six of the 23 patients in whom this analysis was done. The EGF receptor expression was constant in all samples which were studied and even samples with a different DNA content and histologic grade were stables for the EGF receptor expression.  相似文献   
13.
A sensitive enzyme-linked immunosorbent assay (ELISA) was used in a retrospective study of placental alkaline phosphatase (PLAP) levels in serum, cerebrospinal fluid (CSF), and intratumoral cyst fluid in primary intracranial germinoma. The ELISA showed no cross-reactivity with intestinal alkaline phosphatase except in very high concentrations, after samples had been heat-treated. Three patients with germinoma were studied for serum PLAP levels and in all the levels were elevated (3.78, 0.52, and 2.11 IU/liter). Two of the germinoma patients were studied for PLAP levels in the CSF, and both had elevated levels (0.83 and 9.83 IU/liter). The intratumoral cyst fluid in one case of germinoma was tested for PLAP and the level was found to be very high (603 IU/liter). These PLAP levels decreased concomitantly with the reduction in tumor size during irradiation. Serum PLAP levels were measured in 40 control adult male individuals and in the CSF of 20 nonpregnant patients with subarachnoid hemorrhage. The upper normal limits were 0.20 and 0.11 IU/liter in the serum and the CSF, respectively. All PLAP levels measured in the serum of patients with various brain tumors were 0.18 IU/liter or less. This study strongly suggests that PLAP is a clinically useful tumor marker for primary intracranial germinoma.  相似文献   
14.
15.
Eighty of 89 patients who underwent radical resection (resectability 89.9%) for carcinoma of the papilla of Vater between 1976 and 1992 were retrospectively reviewed. Seventy-three patients underwent pancreaticoduodenectomy (PD) and 7 underwent pylorus-preserving pancreaticoduodenectomy (PPPD). The postoperative mortality rate was only 3.8% (3 patients). The 3- and 5-year survival rates were 63.6% and 57.4%, respectively. Important factors influencing long-term survival were Stage (clinical stage = Stage), microscopic lymph node metastasis (n), duodenal wall invasion (d), vascular invasion (v), and the epithelium of origin. Early carcinoma of the papilla of Vater is defined as tumor in which invasion is limited within the papilla of Vater; in particular, carcinomatous invasion is within the muscle of Oddi (d0) with n0. PD and/or PPPD with radical lymph node dissection should be performed for carcinoma of the papilla of Vater, as these procedures can be performed with low morbidity and mortality.  相似文献   
16.
Analysis of DNA ploidy patterns was performed on 76 diffusely infiltrating carcinomas of the stomach and the results correlated with histologic findings and outcome. Twenty six cases were diploid (34%) and 50 cases were aneuploid. There was no correlation between DNA ploidy and histologic type, depth of invasion, lymphatic invasion, evidence of peritoneal dissemination or curability. In aneuploid tumors, incidence of vascular invasion was significantly higher than that in diploid tumors (p less than 0.05). In addition, the patients with aneuploid tumors had a poor prognosis than with diploid tumors. These results indicate that DNA ploidy patterns may possibly be a useful prognostic marker for diffusely infiltrating carcinomas of the stomach.  相似文献   
17.
Summary The growth potential of 65 pituitary adenomas was determined by histochemical analysis with Ki-67 and anti-DNA polymerase monoclonal antibodies, bromodeoxyuridine (BrdUdR) labeling, and counts of argyrophilic nucleolar organizer regions (Ag-NORs). The mean proliferating cell indices (PCIs) determined by Ki-67 and anti-DNA polymerase and the BrdUdR labeling index (LI) were generally very low [1.0±0.2%, 1.1±0.2%, and 0.5±0.1% (±SE), respectively]. Apart from adrenocorticotropic hormone-positive adenomas, which had significantly higher indices, there were no statistically significant differences in the indices among the other subtypes of pituitary adenomas. Recurrent tumors had higher Ki-67 and DNA polymerase PCIs and BrdUdR LIs (3.6%, 4.2%, 1.4%) than primary tumors (0.8%, 0.8%, 0.3%; P<0.005). The number of Ag-NORs did not correlated significantly with any of the three indices. The mean number of Ag-NORs was higher in nonfunctioning adenomas than in functioning adenomas (2.04 vs 1.66, P<0.005); among prolactin-positive adenomas, those treated preoperatively with bromocriptine had more Ag-NORs than untreated tumors (1.75 vs 1.57, P<0.005). These results suggest that the Ki-67 and DNA polymerase PCIs and the BrdUdR LI predict the growth potential of individual pituitary adenomas, whereas the number of Ag-NORs appears to correlate with hormone production rather than with the proliferative potential.Supported by grants CA-13525 and CA-50210 from the National Cancer Institute, by a grant from the Phi Beta Psi Sorority, and by Grant-in-Aid A 63771083 from the Ministry of Education, Science, and Culture of Japan  相似文献   
18.
In the present study, the authors analysed the serial angiographical findings progressing to brain death and their relation to the intracranial pressure (ICP) and the cerebral perfusion pressure (CPP). Seventy two patients, from four to eighty four years old (fourty six males and twenty six females) admitted in the Department of Emergency Medicine, University of Tokyo Hospital during the period from January, 1981 to April, 1986, were studied. Their underlying diseases were supratentorial primary brain lesions except two cases with asphyxias which progressed to brain death. ICP was continuously measured and CPP was calculated as the pressure gradient between the mean arterial blood pressure (MAP) and ICP. The direct carotid angiography was performed to follow the cerebral circulation. Fourty five patients were subjected to barbiturate (pentobarbital sodium) therapy. The degree of the intracranial filling staged as "Non-filling", "Siphon-filling", "Partial-filling", "Delayed-filling", "All-filling" correlated significantly with ICP and CPP. These relationships, however, disappeared once ICP exceeded MAP. When "Non-filling" angiogram was obtained, clinical signs had already showed brain death. On the other hand, minimal flow ("Siphon-filling", "Partial-filling", "Delayed-filling") were still demonstrated in six brain death cases while ICP was approaching its "peak" value. This study showed that clinical diagnosis of brain death preceded the Non-filling phenomenon, suggesting that, for the demonstration of the cerebral circulatory arrest, the angiograms should be performed after the clinical diagnosis of brain death was established and CPP became zero. The evaluation of the extremely slow and minimal filling is still a matter of discussion.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
19.
Elective cesarean as a risk factor for transfusion after delivery of twins   总被引:1,自引:0,他引:1  
We examined deliveries of twins to identify factors most strongly associated with an increased risk of transfusion. We reviewed the obstetric records of 511 twin deliveries at the Japanese Red Cross Katsushika Maternity Hospital from 2003 through 2007. After 18 (3.5%) of these deliveries, transfusions were required. Transfusion was significantly more likely after elective cesarean delivery at a gestational aged of 37 weeks or more (odds ratio, 4.85; 95% confidence interval, 1.87-12.61). Emergency cesarean delivery (at > or =37 weeks' gestation) was not associated with an increased risk of transfusion. The delivery mode of twins should be carefully considered because of the increased risk of transfusion after elective cesarean delivery at a gestational age of 37 weeks or more.  相似文献   
20.
The gene encoding Clostridium sordellii phospholipase C (Csp) was cloned and expressed as a histidine-tagged (His-tag) protein, and the protein was purified to compare its enzymatic and biological activities with those of Clostridium perfringens phospholipase C (Cpa) and Clostridium bifermentans phospholipase C (Cbp). Csp was found to consist of 371 amino acid residues in the mature form and to be more homologous to Cbp than to Cpa. The egg yolk phospholipid hydrolysis activity of the His-tag Csp was about one-third of that of His-tag Cpa, but the hemolytic activity was less than 1% of that of His-tag Cpa. His-tag Csp was nontoxic to mice. Immunization of mice with His-tag Cbp or His-tag Csp did not provide effective protection against the lethal activity of His-tag Cpa. These results indicate that Csp possesses similar molecular properties to Cbp and suggest that comparative analysis of toxic and nontoxic clostridial phospholipases is helpful for characterization of the toxic properties of clostridial phospholipases.  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