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   43482篇
  免费   3448篇
  国内免费   363篇
耳鼻咽喉   412篇
儿科学   1238篇
妇产科学   1194篇
基础医学   5648篇
口腔科学   672篇
临床医学   5006篇
内科学   8886篇
皮肤病学   956篇
神经病学   3135篇
特种医学   1331篇
外科学   5582篇
综合类   1283篇
一般理论   53篇
预防医学   3029篇
眼科学   1816篇
药学   3304篇
中国医学   318篇
肿瘤学   3430篇
  2023年   356篇
  2022年   613篇
  2021年   1174篇
  2020年   789篇
  2019年   1045篇
  2018年   1286篇
  2017年   985篇
  2016年   1102篇
  2015年   1297篇
  2014年   1721篇
  2013年   2110篇
  2012年   3005篇
  2011年   3099篇
  2010年   1754篇
  2009年   1540篇
  2008年   2406篇
  2007年   2533篇
  2006年   2478篇
  2005年   2432篇
  2004年   2163篇
  2003年   2021篇
  2002年   1756篇
  2001年   1180篇
  2000年   1088篇
  1999年   958篇
  1998年   431篇
  1997年   317篇
  1996年   292篇
  1995年   237篇
  1994年   230篇
  1993年   233篇
  1992年   467篇
  1991年   453篇
  1990年   429篇
  1989年   400篇
  1988年   359篇
  1987年   371篇
  1986年   327篇
  1985年   279篇
  1984年   214篇
  1983年   150篇
  1982年   104篇
  1981年   91篇
  1980年   95篇
  1979年   141篇
  1978年   96篇
  1977年   77篇
  1976年   76篇
  1975年   77篇
  1972年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Background : Mortality rates from gastric cancer, apart from those derived from Japanese series, remain poor. This paper sought to determine the present outcome of gastric carcinoma in a predominantly Chinese population in Singapore. Prognostic factors useful in predicting survival were also evaluated in this population. Method : All cases of histologically confirmed gastric adenocarcinoma presenting in 1992 were entered into a prospective database. Prognostic factors related to age, sex, site of disease, depth of invasion, histological grade, nodal status and stage of disease were evaluated in patients with resectable disease to determine their utility in predicting survival. Results : Of 1310 consecutive patients with histologically proven adenocarcinomas, 37% had distant metastases at presentation predominantly in the liver (21%) and peritoneal cavity (20%). Sixty-four per cent of patients underwent surgery and in only 51% of these patients was resection of the turnour possible. Stages 111 and IV (T4N2) locally advanced disease were present in 38% of patients. Thus the majority of patients presented with late or metastatic disease (75%, stages 111 and IV). Sixty per cent of patients were alive at I year and 40% at 2 years after resection of the tumour (Kaplan-Meier survival plots). In contrast, no patient survived longer than a year if the tumour was not resectable (P < 0.001, log-rank test). Median survival of patients without surgery was 12 weeks. Median survival for patients with resected stage IV disease was 23 weeks, compared to 18 weeks after surgical bypass. Age, sex, site, depth of invasion and histological grade did not significantly predict survival. Patients with node-negative disease survived longer (2 year, 70%) than those with nodal involvement (2 years, 44%; P = 0.06, log-rank test). Pathologic staging with the TNM system was useful in predicting survival (P < 0.001). Sixty per cent of patients with stage I and II disease were alive at 2 years compared to 54% with stage III disease and 0% with stage IV disease. Conclusion : The prognosis of stomach cancer remains poor, due predominantly to late presentation. Pathologic TNM staging and nodal status were useful in predicting survival outcome after resection. If the tumour were resectable, survival was appreciable even in patients with advanced stage III (2 years, 54%) and stage IV (1 year, 40%) disease. Strategies to improve outcome should focus on early detection of gastric carcinomas.  相似文献   
93.
EDITORIAL COMMENT: We accepted these case reports for publication not only to remind readers that a classical Caesarean scar is more likely than a lower uterine segment scar to rupture or dehisce, but also to stress that women should be counselled appropriately when classical Caesarean section has been performed. Our Australian population is also mobile and women may not return to the same institution or obstetrician for their next confinement. Tracing the details of a previous delivery from another hospital or practitioner even in the same community should be a routine enquiry when a patient has had a Caesarean section in a previous pregnancy but the required information is often difficult to obtain. The woman herse(fis the essential repository for this information. It should also be noted that the recent increase in the number of Caesarean sections performed for fetal indications before 30 weeks' gestation has resulted in more vertical incisions because of a poorly formed lower uterine segment.  相似文献   
94.
Intensive chemotherapy for peripheral T-cell lymphomas.   总被引:3,自引:0,他引:3  
Forty-two patients with previously untreated peripheral T-cell lymphomas (PTCL) were treated with an intensive chemotherapy protocol. Either the BACOP or the m-BACOD regimen was used for induction. Patients achieving complete clinical remission after three courses were given intensive consolidation and maintenance chemotherapy similar to the L10/L17M protocol designed by the Memorial Sloan-Kettering Group for acute lymphoblastic leukemia and lymphoblastic lymphoma. There were 27 (64 per cent) males and 15 (36 per cent) females. The median age was 54 years (mean 53, range 15 to 68). Seven of them (17 per cent) had stage I disease, four (10 per cent) stage II, seven (17 per cent) stage III and 24 (57 per cent) stage IV. Eighteen patients (43 per cent) had B symptoms and four (10 per cent) had bulky disease. According to the Working Formulation, the histology was diffuse mixed in 16 patients (38 per cent), diffuse large cell in 18 (43 per cent), diffuse immunoblastic in four (10 per cent) and unclassifiable in four (10 per cent). According to a modified Japanese Lymphoma Study Group's classification, the histology in 24 patients (57 per cent) was the pleomorphic type, in 13 (31 per cent) immunoblastic-lymphadenopathy-like (IBL-like), and in five (12 per cent) unclassifiable. The overall complete remission rate was 67 per cent. Twenty-five per cent of the complete responders relapsed and the DFS of the CR patients was 62 per cent at three years. The overall survival of all patients at three years was 52 per cent. Patients with stage I, II and III disease had significantly better CR rate (100 per cent versus 42 per cent, p = 0.001) and overall survival (82 per cent versus 35 per cent at three years, p = 0.01) than those with stage IV disease but the relapse rate and DFS of CR patients were similar. This study shows that the prognosis of patients with PTCL can be improved by intensive therapy.  相似文献   
95.
Because attitudes concerning a topic can diminish the effectiveness of educational materials, previously identified attitudes concerning calcium intake were explored through focus group interviews during the developmental stages of calcium education materials. Although four focus groups of six to seven participants were planned, each of the four groups consisted of two to six women. All focus groups followed the same format, lasting for 60–90 min; questions progressed from the general to more specific. The focus groups revealed several attitudinal barriers toward dietary behavioural change, including lack of prior interest in the topic and lack of time. Attitudes about dairy calcium included the belief that dairy foods were high in fat and should be avoided, and the belief that dairy foods would cause stomach upsets. Also, neither younger nor older women felt that osteoporosis was a problem their age group needed to address. Readability scales were not necessarily predictive of preference. This study shows that focus group interviews make a valuable contribution to planning and evaluating nutrition education materials.  相似文献   
96.
The Australian Leukaemia Study Group myeloma study (MM1) aimed to determine the prognostic significance of clinical and immunophenotypic markers in patients with multiple myeloma. All patients were treated with standard dose melphalan and prednisone. Seventy-four patients were entered and the median survival was 27 months. Serum beta 2-microglobulin (βM) and albumin levels were the only significant clinical factors influencing survival (p = 0.007 and p = 0.008, respectively). Patients with raised levels of CD38+ lymphocytes at presentation had a significantly shorter survival than patients with normal levels (p = 0.01, logrank test, median 19 months vs 33 months). CD38 antigen expression was independent of β2M but patients with raised levels of CD38 had significantly lower levels of albumin than patients with normal levels (p = 0.001) which may explain their poorer survival. Salmon and Durie stage was not associated with antigen expression. No other B-cell antigens (CD10, CD19, CD20, CD21, CD22, CD23, FMC1 or FMC7) or plasma cell antigens tested (PCA-1) were found to be associated with prognosis. Patients who achieved plateau phase had a better prognosis than those who did not (p = 0.04 in a landmark analysis). Patients who achieved plateau phase following an objective response appeared to have a better prognosis than those who were in plateau phase at presentation (p = 0.09 in a landmark analysis). Light chain isotype suppression (LCIS) was not associated with a significant survival advantage and did not correlate with any known prognostic indicator. We conclude that phenotypic analysis of peripheral blood lymphocytes for CD38 antigen at diagnosis may be useful as a prognostic indicator in patients with myeloma.  相似文献   
97.
Short-term and long-term carcinogenicity of methyl carbamate (MCB) was evaluated in F344 rats and B6C3F1 mice. In experiments lasting 6, 12, and 18 months, MCB was given in water by gavage to groups of 10 male and 10 female rats at 0 or 400 mg/kg body weight, 5 days per week, and to similar groups of mice at 0 or 1,000 mg/kg. At 6 months, MCB induced atypical mitoses, cytologic alterations, cytomegaly, pigmentation, necrosis, and neoplastic nodules of the liver in rats. At 12 and 18 months, carcinomas of the liver were induced by MCB in 80-90% of male rats and in 60-80% of female rats. None was observed in control rats or in mice. In the 2-year studies, MCB was given to groups of 50 male and 50 female rats at 0, 100, or 200 mg/kg and to similar groups of mice at 0, 500, or 1,000 mg/kg, 5 days/week. Chronic focal inflammation, cytologic alteration, hyperplasia, and neoplastic nodules and carcinomas (200 mg/kg groups only) of the liver were induced by MCB in rats. Liver tumor incidence data for combined experiments in rats were: males--5% in controls, 0% in 100 mg/kg group, 14% in 200 mg/kg group, and 77% in 400 mg/kg group; females--5% in controls, 0% in controls, 0% in 100 mg/kg group, 12% in 200 mg/kg group, and 63% in 400 mg/kg group. MCB was not shown to be carcinogenic in mice.  相似文献   
98.
We present improvements of a previously reported method of tracheoesophageal puncture for voice restoration in postlaryngectomy patients. Our method utilizes a flexible endoscope to enable the tracheoesophageal puncture to be made under direct visualization using only local anesthesia and intravenous sedation. After 3 days, the created tracheoesophageal fistula tract is mature enough to allow placement of a voice prosthesis in the office. This allows the entire procedure to be performed in an outpatient setting with minimal risk. Received: 24 October 1996/Accepted: 24 January 1997  相似文献   
99.
Background: Investigators in the authors' laboratory previously established the critical participation of the cerulospinal noradrenergic pathway in muscular rigidity elicited by fentanyl. The identification of colocalization of glutamate with tyrosine hydroxylase in most locus ceruleus neurons suggests a role for cerulospinal glutamatergic neurotransmission in fentanyl-induced muscular rigidity. This suggestion and the subtype(s) of glutamate receptors involved were investigated here.

Methods: Electromyographic signals activated by bilateral microinjection of 2.5 micro gram fentanyl into the locus ceruleus were recorded differentially from the left sacrococcygeus dorsi lateralis muscle of adult male Sprague-Dawley rats. The effect of intrathecal administration at the lower lumbar spinal cord of various N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonists or agonists on this index of muscular rigidity was studied. Rats were under mechanical ventilation, and intravenous infusion of ketamine (30 mg [center dot] kg sup -1 [center dot] h sup -1) was maintained until 10 min before fentanyl was administered.

Results: Microinjection of fentanyl bilaterally into the locus ceruleus increased the root mean square and decreased the mean power frequency values of electromyographic signals. The efficacy of fentanyl to elicit muscular rigidity in this manner was significantly reduced by previous intrathecal administration of either 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801), D-(-)-2-amino-5-phosphonovaleric acid (AP5), or (+/- (CPP). Intrathecal administration of kainic acid or NMDA also resulted in significant electromyographic activation.  相似文献   

100.
A pilot project was established from 1992 to 1994 to provide people with chronic schizophrenia living in Dundee, Scotland, with a National Health Service sheltered workshop that would be fully integrated into the local business community. Of the 43 clients who attended the sheltered workshop, 38 agreed to take part in the project. Typical attenders were single, middle-aged men with schizophrenia. Twenty-five per cent had spent more than two years in hospital; 75% had been unemployed for more than five years. The clients' use of National Health Service day facilities more than halved while attending the workshop. Their hospital readmission rates were low (16%) compared with the local readmission rates for people with schizophrenia in Dundee (86%). A training approach based on the general principles of social skills training contributed to positive vocational outcomes for one-third of the workshop clients. The findings suggest that the onus of responsibility for providing work for many individuals with schizophrenia remains with the National Health Service, and in particular, occupational therapy. Occupational therapy staff must assess their clients effectively and provide quality training leading to opportunities for paid employment. These results have implications for the training of occupational therapy staff and also for the staffing structure in sheltered workshops. Copyright © 1997 Whurr Publishers Ltd.  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