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   18884篇
  免费   1148篇
  国内免费   85篇
耳鼻咽喉   182篇
儿科学   600篇
妇产科学   416篇
基础医学   2484篇
口腔科学   371篇
临床医学   2190篇
内科学   4458篇
皮肤病学   527篇
神经病学   1892篇
特种医学   413篇
外科学   1448篇
综合类   103篇
一般理论   8篇
预防医学   1945篇
眼科学   305篇
药学   1279篇
中国医学   69篇
肿瘤学   1427篇
  2024年   12篇
  2023年   167篇
  2022年   327篇
  2021年   544篇
  2020年   329篇
  2019年   525篇
  2018年   643篇
  2017年   403篇
  2016年   483篇
  2015年   549篇
  2014年   768篇
  2013年   993篇
  2012年   1562篇
  2011年   1586篇
  2010年   820篇
  2009年   784篇
  2008年   1292篇
  2007年   1273篇
  2006年   1237篇
  2005年   1230篇
  2004年   1057篇
  2003年   1020篇
  2002年   930篇
  2001年   89篇
  2000年   78篇
  1999年   131篇
  1998年   160篇
  1997年   146篇
  1996年   138篇
  1995年   107篇
  1994年   79篇
  1993年   91篇
  1992年   61篇
  1991年   38篇
  1990年   39篇
  1989年   42篇
  1988年   26篇
  1987年   22篇
  1986年   34篇
  1985年   35篇
  1984年   31篇
  1983年   29篇
  1982年   30篇
  1981年   33篇
  1980年   34篇
  1979年   17篇
  1978年   15篇
  1976年   12篇
  1974年   11篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
Aim: The aim of the study was to investigate whether salivary mineral content may be associated with bone status in women after menopause. Material and methods: The study group consisted of 125 postmenopausal women aged 64.3 ± 6.9 yr, derived from the epidemiological SilesiaOsteoActive Study. All participants underwent hip and spine bone densitometry using dual energy X-ray absorptiometry, dental examination, and saliva content analysis. Data for salivary pH, copper, calcium, phosphorus, and zinc concentrations were evaluated. Results: Mean femoral neck bone mineral density (BMD) was 0.739 ± 0.118 g/cm2, total hip BMD 0.891 ± 0.14 g/cm2, and spine BMD 0.868 ± 0.14 g/cm2. Salivary pH was significantly lower in women with spinal osteoporosis defined as T-score below ?2.5, compared to individuals with normal BMD (pH: 6.65 ± 0.67 vs 6.96 ± 0.58, p < 0.05). There was a significant though weak inverse correlation between Ca concentration in saliva and femoral neck BMD (r = ?0.23, p < 0.05). Conclusions: High salivary calcium content and low salivary pH may be indicative of low hip and decreased spine BMD, respectively. These associations may reflect demineralization process (calcium redistribution) influencing bone, and a negative effect of acidity on mineral tissues, although causal pathway remains not clear.  相似文献   
122.
Letermovir is a new antiviral drug approved for the prophylaxis of CMV infection in allogeneic stem cell transplants. The aim of the study was to assess the therapeutic efficacy of letermovir in difficult to treat CMV infections in lung transplant recipients. All lung transplant recipients between March 2018 and August 2020, who have been treated with letermovir for ganciclovir-resistant or refractory CMV infection were included in the study and analysed retrospectively. In total, 28 patients were identified. CMV disease was present in 15 patients (53.6%). In 23 patients (82.1%), rapid response was noticed, and CMV-viral load could be significantly decreased (>1 log10) after a median of 17 [14–27] days and cleared subsequently in all of these patients. Five patients (17.9%) were classified as non-responder. Thereof, development of a mutation of the CMV UL56 terminase (UL-56-Gen: C325Y) conferring letermovir resistance could be observed in three patients (60%). Common side effects were mild and mostly of gastrointestinal nature. Mild adjustments of the immunosuppressive drugs were mandatory upon treatment initiation with letermovir. In addition to other interventions, letermovir was effective in difficult to treat CMV infections in lung transplant recipients. However, in patients with treatment failure mutation conferring letermovir, resistance should be taken into account.  相似文献   
123.
Background:A worldwide personal protection equipment (PPE) shortage has emerged during COVID-19 pandemic, contributing to the high incidence of SARS-CoV-2 infection among health care providers. To address this lack of PEE, new solutions have been researched. Among those, full-face snorkeling masks demonstrated to be an interesting option. Among surgical specialties otolaryngologists and thoracic surgeons are at high risk of infection, due to the close contact with airway secretions.Objectives:We tested the comfort and usability of a modified full-face snorkeling mask (Ocean Reef Mask Aria QR+) as a protective device for otolaryngologic and thoracic surgeries.Methods:The mask was customized with a 3D-printed adaptor supporting many industrial filter types, including FFP3 and heat and moisture exchangers (HME). We evaluated surgical performances of the mask, both subjectively, with a questionnaire filled in by the surgeons, as well as objectively, monitoring transcutaneous PCO2 and PO2 values of surgeons during surgical procedures.Results:The modified full-face snorkeling mask was tested during 9 otolaryngologic and 15 thoracic surgery procedures. The device demonstrated very good overall vision quality with some limitations regarding lateral vision and almost no difficulties in usability. Water condensation into the mask was absent in almost every case. Both PO2 and PCO2 parameters remained within normal ranges during every procedure.Discussion:The modified full-face snorkeling mask can be an innovative PPE. In the current COVID-19 pandemic scenario, the worldwide shortage of protective masks and goggles may exploit this ready-to-use and low-cost solution, especially for high-risk surgical procedures.  相似文献   
124.
Mantle cell lymphoma (MCL) is a B-cell neoplasm with a relatively aggressive clinical course. There is a very small subgroup of patients who present with atypical lymphocytes in peripheral blood, with or without lymphocytosis, lymphadenopathy, or splenomegaly, and with an indolent clinical course. They frequently show mutated IgV(H) genes and CD5 negativity. We report an asymptomatic elderly patient who presented with a single submandibular lymphadenopathy. The biopsy showed immunophenotype and t(11;14)(q13;q32) consistent with MCL. The abnormal lymphoid population was also detected in peripheral blood and bone marrow. The patient has remained asymptomatic for 5 years without receiving any therapy. It is uncertain whether these cases represent an early-stage event in the development or an indolent form of MCL. The existence of such asymptomatic patients with an indolent clinical course should induce a strict clinical judgment in terms of therapeutic decisions.  相似文献   
125.
With the aid of the Basic Sequential Analytical Simplex Method the in vitro anti-trichomonad effectiveness of several metronidazole/gossypol blends was determined. While the combination that produced 50% of growth inhibition on trichomonad cultures (IC(50)) contained 15.1 muM gossypol and 0.087 muM metronidazole, the IC(50) of metronidazole and gossypol tested separately was 38.08 muM and 0.195 muM, respectively. Thus, the IC(50) of mixed gossypol and metronidazole was, respectively 60.34 and 55.4% lower than that of each separated drug. Whereas metronidazole is usually administered orally, gossypol, used as spermicide, is formulated as pessary. In such conditions the absorption of metronidazole is very efficient while that of gossypol is strikingly poor. The above suggest that a gossypol-metronidazole anti-trichomoniasis therapeutic scheme could be as effective as metronidazole alone, but less toxic.  相似文献   
126.
Relationship between Cigarette Dose and Perceived Risk of Lung Cancer   总被引:1,自引:0,他引:1  
BACKGROUND: Most people are aware that smoking cigarettes increases the risk of ill health, in particular of lung cancer. The precise way in which they relate amount of exposure to smoke and level of health risk has not, however, been determined. METHODS: A convenience sample of 155 French adolescents and adults ages 15 to 75 rated the risk of "smoker's cancer"--the popular term for lung cancer--in 24 scenarios depicting eight levels of daily cigarette consumption of three concentrations of nicotine. The data were analyzed according to functional measurement methodology to ascertain the forms of the relationship between exposure and perceived risk. RESULTS: All subjects perceived that the risk of smoker's cancer increased as smoking increased. Yet at high levels of consumption, additional cigarettes were generally judged to result in decreasing increments of risk, regardless of the nicotine content of the cigarettes and the sex and smoking status of the participants. Adolescents, however, were more likely than adults to perceive a linear, rather than a negatively accelerated, relationship. CONCLUSIONS: The actual form of the relationship between the dose of cigarette smoke and risk of lung cancer is either linear or positively accelerated. Public health educators and physicians should be aware that, at least in France, many people, particularly adults, incorrectly perceive this relationship as negatively accelerated.  相似文献   
127.
Because of the limited number of case reports on the use of electroconvulsive therapy (ECT) in adolescent psychiatric patients, we retrospectively reviewed the medical records of 20 young patients who underwent ECT. They constituted all the patients 相似文献   
128.
Summary The authors studied the behavior of normal subjects and paranoid schizophrenic patients in a simple problem-solving situation. The schizophrenics were divided into two sample groups, one of individuals under treatment and the other of individuals not under treatment.The learning process involved in this problem-solving situation is very similar to an instrumental conditioning, and can be understood by means of the following assumptions: (1) the subjects use decision functions in reacting to the stimuli, although they may be not fully aware of this; (2) learning is the result of successive transformations of these decisions in the course of time; (3) the changes have specific probabilities and are related to (a) those responses which are made to the latest stimuli, and (b) a differential probability for decision functions which were effective, or only interrupted painful reinforcement, or were completely ineffective.In schizophrenics further factors of importance were (1) an inertia factor and (2) the rigidly continued use of unsuccessful or only partially successful decision criteria.The authors used a systems theory based on Galois field theory and a calculus of operators specifying three groups of subjects. A computer program based on these hypotheses was tested in a simulation experiment.The statistical evaluation of the results showed a congruence between the theoretical approach and the experimental data.This work was carried out with financial support from the Institute de Alta Cultura, Lisbon, between 1970 and 1974  相似文献   
129.
Two children with extensive ileal resection are reported. They developed gross haematuria of non-glomerular origin, without stones or nephrocalcinosis. Previous reports indicate that acquired hyperoxaluria is common in children with a variety of intestinal disorders. Our patients had hyperoxaluria. We think that hyperoxaluria may be the cause of haematuria through a pathogenetic mechanism similar to the one ascribed to haematuria secondary to hypercalciuria and hyperuricosuria.  相似文献   
130.
Shepard's mental rotation paradigm (e.g. Shepard and Metzler, 1971) was modified to allow tachistoscopic presentation of stimuli at varying angles of orientation (0° to 180°) in the right and left visual fields. Thirty male and thirty female subjects divided into three handedness groups (right-handers, non-familial and familial left-handers) judged whether a stimulus was a standard form or its mirror image. In general response times for correct judgements (RTc) increased monotonically as a function of angle of orientation though the curves tended to be negatively accelerated rather than linear. Right-handers showed a slower rate of increase in RTc as a function of angle than either left-handed group. Mean RTc and the rate of increase in RTc were equivalent for the two sexes and for the two visual fields. Both mean RTcs and on the rate of increase in RTc varied as a function of the stimulus.Error rates also increased monotonically as a function of angle of orientation. No sex or handedness differences in error rates were found. However, errors increased significantly less rapidly when stimuli were presented in the left visual field. It is argued that right hemisphere specialization for spatial processing minimizes the rate of increase in errors.The present failure to find sex differences may be of interest and it is argued that rapid presentation of stimuli results in subjects setting maximum and minimun response times. Within this relatively restricted “bandwith” of response times males and females may perform spatial tasks equally efficiently. Some confirmation for this hypothesis vs. an alternative based upon differences in hemispheric organization was found in a second experiment.  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