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   18572篇
  免费   1490篇
  国内免费   318篇
耳鼻咽喉   4174篇
儿科学   399篇
妇产科学   594篇
基础医学   1804篇
口腔科学   1979篇
临床医学   991篇
内科学   1641篇
皮肤病学   626篇
神经病学   956篇
特种医学   321篇
外科学   2352篇
综合类   1024篇
现状与发展   2篇
一般理论   2篇
预防医学   1665篇
眼科学   413篇
药学   654篇
  7篇
中国医学   159篇
肿瘤学   617篇
  2024年   33篇
  2023年   411篇
  2022年   441篇
  2021年   946篇
  2020年   837篇
  2019年   924篇
  2018年   827篇
  2017年   796篇
  2016年   808篇
  2015年   817篇
  2014年   1207篇
  2013年   1830篇
  2012年   900篇
  2011年   939篇
  2010年   768篇
  2009年   828篇
  2008年   794篇
  2007年   751篇
  2006年   668篇
  2005年   588篇
  2004年   488篇
  2003年   433篇
  2002年   364篇
  2001年   349篇
  2000年   295篇
  1999年   248篇
  1998年   233篇
  1997年   225篇
  1996年   164篇
  1995年   171篇
  1994年   141篇
  1993年   113篇
  1992年   119篇
  1991年   106篇
  1990年   80篇
  1989年   90篇
  1988年   73篇
  1987年   54篇
  1986年   43篇
  1985年   76篇
  1984年   76篇
  1983年   47篇
  1982年   54篇
  1981年   39篇
  1980年   48篇
  1979年   34篇
  1978年   25篇
  1977年   25篇
  1976年   16篇
  1975年   18篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
目的用畸变产物耳声发射(distortion-product otoacoustic emission,DPOAE)来观察系统性低血压和慢性进行性听力损伤的关系。方法实验组为34例体检中发现的系统性低血压患者(诊断标准:舒张压<60mmHg,收缩压<90mmHg),对照组由年龄、性别相匹配的30例正常人组成,两组在同一实验室中进行了生化、心血管、耳鼻咽喉专科和纯音测听、声阻抗、DPOAE等听力学检查。将两组的各项结果进行比较。结果实验组DPOAE听力图结果显示16例患者有一个以上频率轻到中度的听力损伤,主要在低频范围。与对照组相比,实验组的DPOAE幅值在一个以上的频率低下甚至缺失。结论系统性低血压有可能是导致耳蜗功能损伤的因子之一,而DPOAE可作为早期监测此类患者耳蜗功能损伤情况的有效工具。  相似文献   
102.
[目的]用因子logistic回归分析的方法探讨噪声作业工人听力的影响因素。[方法]调查某钢铁企业的2 491名噪声作业工人,对可能影响听力结果的13项指标进行研究,找出其公因子再与电测听结果作逐步logistic回归分析。[结果]血压、烟酒嗜好、日均接触时间、噪声接触、心脏功能、症状等6个回归因子对作业工人听力有一定的影响。[结论]噪声作业工人应减少不良嗜好,加强个体防护。  相似文献   
103.
Skin reactions to irritants assessed by non-invasive bioengineering methods   总被引:3,自引:1,他引:2  
Pathophysiological components of irritant contact dermatitis caused by 3 chemically-different irritants were investigated. 20 healthy volunteers were patch tested with sodium lauryl sulphate, nonanoic acid and hydrochloric acid on the flexor side of the upper arm. The skin response was evaluated after 24, 48 and 96 h by visual scoring and measured by the following bioengineering methods: transepidermal water loss measurement, electrical conductance for measurement of skin hydration, laser Doppler flowmetry for measurement of cutaneous blood flow and 20 MHz ultrasound A-scan for measurement of skin thickness. In spite of homogeneous inflammatory responses, significant differences in the severity of the injury to the skin barrier function caused by the different irritants were found. Also significant differences between irritants were found in the time course of development of maximum irritant reactions. Bioengineering methods indicating inflammatory responses (measurement of blood flow and skin thickness) were helpful in quantifying the irritant response in general, while bioengineering methods indicating epidermal damage (measurement of TEWL and electrical conductance) were helpful in classifying the individual irritants.  相似文献   
104.
Recommendations for increased consumption of protein are among the most common approaches of popular or fad diets. This review summarizes the effects of dietary protein on satiety, energy intake, thermogenesis, and weight loss, as well as its effect on a variety of health outcomes in adults. In short-term studies, dietary protein modulates energy intake via the sensation of satiety and increases total energy expenditure by increasing the thermic effect of feeding. Whereas these effects did not contribute to weight and fat loss in those studies in which energy intake was fixed, one ad libitum study does suggest that a high-protein diet results in a greater decrease in energy intake, and therefore greater weight and fat loss. In terms of safety, there is little long-term information on the health effects of high-protein diets. From the available data, however, it is evident that the consumption of protein greater than two to three times the U.S. Recommended Daily Allowance contributes to urinary calcium loss and may, in the long term, predispose to bone loss. Caution with these diets is recommended in those individuals who may be predisposed to nephrolithiasis or kidney disease, and particularly in those with diabetes mellitus.  相似文献   
105.
106.
This paper aims to review the evidence for long‐term effectiveness of weight loss on cholesterol, high‐density lipoprotein (HDL), low‐density lipoprotein (LDL) and triglycerides in overweight/obese people. Current evidence is mostly based on short‐term studies. A systematic review of long‐term lipid outcomes of weight loss in studies published between 1966 and 2001, was conducted. Inclusion criteria included all cohort studies and trials carried out on participants with body mass index of greater than or equal to 28 kg m?2. Studies had at least two weight change measurements and follow‐up of more than 2 years. Thirteen long‐term studies with a follow‐up of more than 2 years were included. Cholesterol has a significant positive linear relationship with weight change (r = 0.89) where change in weight explains about 80% of the cholesterol difference variation (Adj R2 = 0.80). For every 10 kg weight loss a drop of 0.23 mmol L?1 in cholesterol may be expected for a person suffering from obesity or are grossly overweight. Weight loss has long‐term beneficial effects especially on LDL and cholesterol. Weight loss in obese patients should be encouraged and sustained.  相似文献   
107.
The present trial was designed to evaluate clinical scores (single observer) of sodium lauryl sulphate (SLS)-induced skin irritation in a group of subjects (n = 10) over a 10-day period along with various skin function parameters. In order to avoid significant variations due to secondary phenomena, the following parameters were recorded with non-invasive instruments in this order: skin capacitance (C1; arbitrary units; CM420 Corneometer), transepidermal water loss (TEWL; g/m2.h; Evaporimeter) and laser Doppler flowmetry (CBFV: cutaneous blood flow values; Periflux). All examinations were performed during winter on reclined relaxed subjects present for at least 10 min in a test room with controlled temperature and relative humidity (t degrees: 19.5-20.7 degrees C and RH: 47.3-60.3%). The analysis of differential data (delta = value at tx-value before test; 2-way ANOVA) was made on single parameters as a function of site (volar forearm versus neck) and time (from 24 h after 48-h occlusion with 5% SLS up to 10 days later). The profile of erythema scores over time differed between neck and forearm, but the delta CBFV readings with the laser Doppler instrument did not detect significant site-time interactions. Roughness (blind evaluation with palpating finger) and capacitance readings (delta C1) showed significant differences between sites, but the profile over time was similar in both locations. delta TEWL did not differ according to anatomical location. The reason for different erythema scores on neck and forearm might be related to inherent regional variation of optical properties of the skin or to a substantial contribution of SLS-induced roughness to the readings of erythema.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
108.
We reviewed data from 47 patients who were treated for endophthalmitis at our hospital during the 11-year period 1980-90. The most common clinical features were hypopyon (75%), diminished vision (72%), ocular pain (68%), discharge (57%), corneal oedema (51%), conjunctival injection (49%), abnormal red reflex (34%), corneal ulcer (32%) and corneal perforation (6%). A total of 54 isolates were obtained from 41 (87%) of the 47 patients. Gram-positive bacteria were more common (72%), than Gram-negative organisms (22%). Two cases were due to fungi, and herpes simplex virus was isolated from one case. The two most common Gram-positive organisms were coagulase-negative staphylococci (25%), and Staphylococcus aureus (11%), while Pseudomonas aeruginosa predominated among the Gram-negative bacteria isolated (15%). Mixed bacterial species were obtained from 29% of the infected patients, including one from whom Vibrio fluvialis was isolated. Predisposing factors included ocular surgery (60%)--mostly for cataract extraction (47%), penetrating trauma (15%) and periocular (15%) or systemic (11%) infections. All patients received antibiotics (generally chloramphenicol and/or a beta-lactamase-stable penicillin plus an aminoglycoside) prior to culture, when treatment was adjusted according to specific aetiological agents. Seventy-nine per cent of patients received topical or systemic steroids. Vitrectomy (diagnostic and therapeutic) was performed on 21% of patients. Sixty-three per cent of culture-positive patients lost vision (no perception of light) in the affected eye, compared to 17% of culture-negative cases (P < 0.05 Fisher exact test). Similarly, a better visual outcome (acuity of 6/12 or better) was associated with coagulase-negative staphylococcal infection than with streptococcal or fungal infections.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
109.
A microprocessor-based real-time digital vibrotactile vocoder system has been developed to train the deaf and for artificial hearing research. The system is composed of a microcomputer module with a digital signal processor interface units and an attenuator/driver circuit. Live or digitised (stored or synthetic) speech is presented to the skin spectrally through a belt housing eight or 16 vibrators. Speech is processed in real time using a fast Fourier transform. The system is also capable of presenting any arbitrary spatiotemporal pattern on the skin for artificial hearing experiments. A preliminary experiment with a deaf subject indicates that the system is potentially an effective device for artificial hearing.  相似文献   
110.
Objective: To investigate the expression of integrin α4 in osteosaxcoma and significance. Methods- Forty-six patients with osteosarcoma (Enneking Ⅰ-Ⅲ) were analyzed for the expression of α4 integrin subunit using immunohistochemical method. Results: Twenty-nine (63.04%) of 46 samples demonstrated positive (+-++) integrin α4 expression. Loss expression of integrin α4 was observed in the patients with advanced Enneking stage (P=0.0040) and with metastatic disease at presentation (P=0.0158). Integrin α4 expression correlated with cell differentiation, the level of malignancy and the invasive behavior of osteosaxcoma. Conclusion: The loss expression of integrin α4 subunit might be a predictor indicating the invasive potential of osteosarcoma and play a role in metastasis of osteosaxcoma patients.  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