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   18330篇
  免费   824篇
  国内免费   124篇
耳鼻咽喉   105篇
儿科学   635篇
妇产科学   505篇
基础医学   2061篇
口腔科学   492篇
临床医学   1354篇
内科学   4849篇
皮肤病学   309篇
神经病学   1906篇
特种医学   796篇
外国民族医学   2篇
外科学   2419篇
综合类   51篇
一般理论   2篇
预防医学   827篇
眼科学   228篇
药学   1017篇
中国医学   12篇
肿瘤学   1708篇
  2023年   133篇
  2022年   276篇
  2021年   462篇
  2020年   266篇
  2019年   382篇
  2018年   477篇
  2017年   349篇
  2016年   481篇
  2015年   479篇
  2014年   680篇
  2013年   867篇
  2012年   1318篇
  2011年   1310篇
  2010年   760篇
  2009年   689篇
  2008年   1259篇
  2007年   1130篇
  2006年   1206篇
  2005年   1114篇
  2004年   1102篇
  2003年   987篇
  2002年   904篇
  2001年   193篇
  2000年   141篇
  1999年   208篇
  1998年   190篇
  1997年   162篇
  1996年   132篇
  1995年   132篇
  1994年   116篇
  1993年   120篇
  1992年   119篇
  1991年   101篇
  1990年   96篇
  1989年   80篇
  1988年   72篇
  1987年   72篇
  1986年   74篇
  1985年   52篇
  1984年   82篇
  1983年   47篇
  1982年   59篇
  1981年   42篇
  1980年   45篇
  1979年   31篇
  1978年   36篇
  1977年   25篇
  1976年   20篇
  1974年   20篇
  1972年   17篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Human immunodeficiency virus (HIV)-associated progressive multifocal leukoencephalopathy (PML) remains a relevant clinical problem even in the era of highly active antiretroviral therapy (HAART). Aims of the study were to analyze clinical and treatment-related features and the survival probability of PML patients observed within the Italian Registry Investigative Neuro AIDS (IRINA) during a 29-month period of HAART. Intravenous drug use, the presence of focal signs, and the involvement of white matter at neuroradiology increased the risk of having PML. A reduced probability of PML was observed when meningeal signs were reported. Patients starting HAART at PML diagnosis and previously naïve for antiretrovirals showed significantly higher 1-year probability of survival (.58), compared to those continuing HAART (.24), or never receiving HAART (.00). Higher CD4 cell count were associated with a higher survival probability (.45). At multivariate analysis, a younger age, higher CD4, starting HAART at PML diagnosis, the absence of previous acquired immunodeficiency syndrome (AIDS)-defining events, and the absence of a severe neurologic impairment were all associated with a reduced hazard of death. The use of cidofovir showed a trend towards a reduced risk of death.  相似文献   
32.
33.
In the Abruzzo Region (Central Italy) there is a lack of measurements of gamma-ray activity in soils and waters. For this reason, we have planned to carry out a systematic measurement of soils in the area of the Provincia dell'Aquila, which covers about one-half of the entire region. In this paper we report the results obtained from 56 soil samples, collected in the northern part of the area of interest (about one-fourth of the total area under study). The results, in terms of content of uranium, thorium and potassium and the activity of caesium are reported, as well as the details on the experimental procedure. The results show a limited content of K and U, with no large variations from site to site, in agreement with the expectations based on the knowledge of the geo-lithological nature of the soil. The amount of Th is also quite limited, with a few exceptions where the Th content is up to five times the average value. Caesium, originated from the fall-out following the Chernobyl accident, is very irregularly distributed owing to the complicated orography of the land. Future plans are also shortly discussed.  相似文献   
34.
The aim of this work is to correlate the net kidney uptake of99mTc-aprotinin (TcA) in 103 subjects with separate effective renal plasma flow (ERPF) and some blood chemistry parameters at 90, 180, and 360 min postinjection both in the normal and diseased kidney. Correlations found with separate ERPFs are highly significant at any time (P < 0.001). However, although the slope of the regression line is steeper at 180 min,r tends to deteriorate slightly with time postinjection and a higher intercept on they axis: this pattern is more pronounced if diseased kidneys are considered separately. The following are probably related to the renal handling of TcA: (1) Early scans better reflect blood flow to the kidney, while later scans are more related to the metabolism/excretion tubular mechanisms; (2) correlations found with urea, creatinine, urea clearance, and creatinine clearance are highly significant at any time; (3) in 20 additional patients with diseased kidneys, renal uptake measurements done 360 min postinjection first with TcA and then with DMSA showed better correlations with ERPF employing TcA. Our results indicate that TcA is a feasible indicator of split renal function even at 90 min postinjection when a scan is easily carried out on an outpatient basis.This paper was in part presented at the European Nuclear Medicine Congress, August 14–17, 1984, Helsinki, Finland  相似文献   
35.
The pharmacokinetics and metabolism of 4-demethoxydaunorubicin (idarubicin, IDA) were studied in 21 patients with advanced cancer after i.v. (12 mg/m2) and oral (30-35 mg/m2) treatment according to a balanced crossover design. Patients were divided into four groups: subjects who showed normal liver and kidney function (group N), those who presented with normal kidney function and liver metastases (group L), those with kidney dysfunction (creatinine clearance, less than or equal to 60 l/h; group R), and those with both liver and kidney dysfunction (group LR). Five patients showed variations in liver or kidney function after the first treatment and were considered to be nonevaluable for the crossover study but evaluable for the liver/kidney function study; some of them appeared in different groups for the i.v. as opposed to p.o. treatments. After i.v. administration, IDA plasma levels followed a triphasic decay pattern. The main metabolite observed in all patients was the 13C-reduced compound (IDAol), which attained plasma levels 2-12 times higher than those of the parent compound. IDA pharmacokinetics was not dependent on the presence of liver metastases but was related to the integrity of kidney function. Analysis of variance indicated a significant correlation between IDA plasma clearance and creatinine clearance; it was also found that IDA plasma clearance was lower in patients whose creatinine clearance was less than 60 ml/min [group N, 122.8 +/- 44.0 l/h; group L, 104.4 +/- 27.7 l/h (P = 0.58) vs group R, 83.4 +/- 18.3 l/h (P = 0.037)]. The IDAol terminal half-life and mean residence time (MRT) were significantly increased in patients with impaired kidney function [MRT: group N, 63.6 +/- 10.8 h; group L, 69.9 +/- 10.2 h (P = 0.27) vs group R, 83.2 +/- 10.9 h (P = 0.025) and t1/2 gamma: group N, 41.3 +/- 10.1 h; group L, 47.0 +/- 7.4 h (P = 0.31) vs group R, 55.8 +/- 8.2 h (P = 0.025)]. After oral treatment, drug absorption occurred during in the first 2-4 h after IDA administration; a biphasic decay pattern was observed thereafter. The main metabolite observed in all patients was again IDAol. The AUC of IDAol was greater after oral administration than after i.v. treatment in proportion to the AUC of IDA (i.v.: AUC-IDAol/AUC-IDA, 2.4-18.9; p.o.: AUC-IDAol/AUC-IDA, 4.1-21.4). Following oral dosing, a substantial amount of 4-demethoxydaunomycinone (AG1) was found in 11/21 patients.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
36.
37.
The goal of this classification of bone defects related to dental implant placement is to help clinicians accurately discuss proposed treatment regimens and organize treatment for clinical correction. A further goal of this effort to categorize bone defects requiring bone augmentation for implant placement is to standardize terminology to allow for more accurate dental communication. The 5 most encountered categories of bony defects are described.  相似文献   
38.
Total extrusion of the talus without recovery of the bone is a very unusual injury. The authors present a case of a 25-year-old man who sustained an open total enucleation of the talus in a motorcycle accident. The talus was not recovered at the scene of the accident. An immediate tibiocalcaneal stabilization was performed by using an external fixator. In the postoperative period, a polymicrobic infection was observed and treated with parenteral antibiotics. Nine months after injury, the patient developed an infection of both the empty space and the distal third of the tibia. A wound debridement with tibial sequestrectomy and insertion of gentamicin-impregnated polymethylmethacrylate beads was performed. Three months later, after multiple negative bacteriologic examinations, a tibiocalcaneal arthrodesis with staples and autogenous bone graft was performed. Because of a pseudoarthrosis, the patient underwent a revision of the arthrodesis by retrograde tibiocalcaneal nailing, achieving clinical and radiographic success. The definitive treatment of total enucleation of the talus is still controversial because of its rarity and the high rate of complications, such as avascular necrosis, osteomyelitis, and ankle stiffness. In this case, without recovery of the talus, retrograde nailing afforded good stability by bypassing the bone defects.  相似文献   
39.
The relationship between farming and cancer risk was investigated in an integrated series of case-control studies conducted from 1985 to 1991 in the Friuli Venezia Giulia region, north-east Italy. Patients with cancer of the oral cavity and pharynx, larynx, oesophagus, colon and rectum, pancreas, breast, thyroid gland, kidney and urinary tract, bladder, prostate, soft-tissue sarcomas, Hodgkin's diseases, non-Hodgkin's lymphomas and multiple myelomas, and controls admitted to hospital for acute, non-neoplastic conditions, were interviewed. For males, a significantly elevated relative risk was seen for oral cavity and pharynx. Farming, however, was associated with a significant protection against cancer of the colon and rectum and bladder. In females, only one significant association emerged, for multiple myeloma. A few significant interactions between cancer risk and year of birth (i.e., before 1930 or 1930 and after) were observed. The risk of cancer of the larynx was significantly elevated in younger male farmers but not in older ones. Our multi-site case-control study confirms that farmers have, for some cancer sites, a distinctive pattern. Excesses of cancer of the oral cavity and pharynx in farmers are characteristic of the present study area and, possibly, of similar European rural populations who have in common high levels of alcohol consumption and, at least in the past, unbalanced diets.  相似文献   
40.
The effects of quercetin have been investigated on the gastrointestinal propulsion of charcoal meal in mice. Quercetin reduced the rate of intestinal transit and this effect was potentiated by verapamil.  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