全文获取类型
收费全文 | 5123篇 |
免费 | 402篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 99篇 |
妇产科学 | 134篇 |
基础医学 | 599篇 |
口腔科学 | 92篇 |
临床医学 | 566篇 |
内科学 | 1116篇 |
皮肤病学 | 55篇 |
神经病学 | 358篇 |
特种医学 | 174篇 |
外国民族医学 | 1篇 |
外科学 | 1081篇 |
综合类 | 88篇 |
一般理论 | 3篇 |
预防医学 | 303篇 |
眼科学 | 161篇 |
药学 | 295篇 |
中国医学 | 14篇 |
肿瘤学 | 379篇 |
出版年
2023年 | 46篇 |
2022年 | 109篇 |
2021年 | 201篇 |
2020年 | 101篇 |
2019年 | 166篇 |
2018年 | 176篇 |
2017年 | 154篇 |
2016年 | 149篇 |
2015年 | 167篇 |
2014年 | 234篇 |
2013年 | 262篇 |
2012年 | 440篇 |
2011年 | 424篇 |
2010年 | 217篇 |
2009年 | 181篇 |
2008年 | 280篇 |
2007年 | 265篇 |
2006年 | 283篇 |
2005年 | 272篇 |
2004年 | 225篇 |
2003年 | 232篇 |
2002年 | 196篇 |
2001年 | 72篇 |
2000年 | 66篇 |
1999年 | 57篇 |
1998年 | 37篇 |
1997年 | 26篇 |
1996年 | 23篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 13篇 |
1992年 | 38篇 |
1991年 | 29篇 |
1990年 | 27篇 |
1989年 | 28篇 |
1988年 | 21篇 |
1987年 | 17篇 |
1986年 | 15篇 |
1985年 | 14篇 |
1984年 | 19篇 |
1983年 | 15篇 |
1982年 | 14篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1977年 | 13篇 |
1976年 | 15篇 |
1973年 | 13篇 |
1972年 | 25篇 |
1971年 | 21篇 |
排序方式: 共有5546条查询结果,搜索用时 15 毫秒
11.
Q Abdool Karim S S Abdool Karim E Preston-Whyte 《Suid-Afrikaanse tydskrif vir geneeskunde》1992,82(5):360-362
This study assessed the ability and preparedness of staff at family planning clinics in Durban to assist in AIDS prevention by promoting condom use among teenagers. Staff at 12 randomly selected clinics were interviewed to assess their attitudes towards teenagers seeking condoms, the information imparted on AIDS and condom use, constraints faced in delivering services, and their perceived role in controlling the spread of AIDS. Despite their awareness of AIDS, those interviewed perceived their role to be that of promoting contraception. Condoms were perceived as a poor choice of contraceptive and their use was discouraged. The pamphlets dispensed along with condoms were thought to provide adequate information about condom use. Information on AIDS was given only if the clinic attender initiated discussion on the subject. Most of the clinic staff were keen to discuss other issues during their consultations, but felt constrained by the large numbers of people they had to attend to and the lack of adequate facilities. If family planning services are to play a role in controlling the spread of AIDS, the first step must be to make this function part of the overall policy. For there to be effective counselling on AIDS prevention, in-service training of current staff is required, as well as more staff and improvements in facilities to ensure greater privacy. 相似文献
12.
Inhibition of allergic airways inflammation and airway hyperresponsiveness in mice by dexamethasone: role of eosinophils,IL-5, eotaxin,and IL-13 总被引:4,自引:0,他引:4
Eum SY Maghni K Hamid Q Eidelman DH Campbell H Isogai S Martin JG 《The Journal of allergy and clinical immunology》2003,111(5):1049-1061
BACKGROUND: Glucocorticoids inhibit allergen-induced airway eosinophilia and airway hyperresponsiveness (AHR). Whether glucocorticoids mediate their effects on AHR by inhibiting eotaxin and IL-5, 2 of the principal mediators of eosinophilia, or through IL-13, an important mediator of AHR, has not been established. OBJECTIVE: We sought to investigate the effects of glucocorticoids on airway eosinophilia and the expression of IL-5, eotaxin, and IL-13 in relation to the induction of AHR in a murine model of allergic asthma. METHODS: Dexamethasone (4 mg/kg) and mAbs against eotaxin (80 micro g/kg) and IL-5 (100 micro g/kg) singly and in combination were administered to immunized mice before antigen challenge. Airway responsiveness to methacholine was measured in anesthetized and mechanically ventilated animals. Eotaxin, IL-5, and IL-13 in bronchoalveolar lavage fluid (BALF), lung homogenates, or both were measured by means of ELISA. RESULTS: A single antigen challenge induced AHR that lasted at least 10 days. Eotaxin protein and mRNA levels increased in lung tissue but not in BALF after challenge. IL-5 protein and mRNA levels increased both in BALF and in lung tissue. Dexamethasone reduced airway eosinophilia, AHR, and protein and mRNA for eotaxin and IL-5. Anti-murine eotaxin and anti-IL-5 antibodies alone and in combination reduced the ovalbumin-induced airway eosinophilia significantly but failed to inhibit AHR. Both dexa-methasone and anti-IL-5/anti-eotaxin inhibited the increases in lung IL-13 levels after ovalbumin challenge to a similar extent. CONCLUSION: These findings suggest that the inhibition of AHR by the glucocorticoid dexamethasone does not appear to be explained by effects on eosinophilia, eotaxin, IL-5, or IL-13. 相似文献
13.
14.
15.
Evaluation of cleaving agents other than trypsin in direct agglutination test for further improving diagnosis of visceral leishmaniasis. 总被引:3,自引:0,他引:3 下载免费PDF全文
A el Harith S Chowdhury A al-Masum S Semio-Santos E Karim S el-Safi I Haque 《Journal of clinical microbiology》1995,33(8):1984-1988
Trypsin treatment of Leishmania promastigote antigen has proved to be indispensible in the direct agglutination test (DAT) for the diagnosis of visceral leishmaniasis (VL) and canine visceral leishmaniasis (CVL). In the present study four antigen batches were prepared with pronase (400 micrograms/ml), lipase (0.45% [wt/vol]), pancreatin (0.3% [wt/vol]), or 2-mercaptoethanol (2-ME) (1.2% [vol/vol]) at a ratio of 20:1 versus promastigote packed cell volume or a density of 10(8)/ml. Batches prepared in this way performed satisfactorily when compared with the performance of the initial trypsinated antigen. Even higher was the sensitivity and specificity of the 2-ME-processed antigen, scoring a minimum DAT titer of 1:102,400 in the VL and CVL group and a maximum of 1:400 in the negative control group. Corresponding titers ranging from 1:6,400 to 1:12,800 and 1:800 to 1:1,600 were obtained with the antigen variants processed with pronase, lipase, pancreatin, or trypsin. By combining the use of indigenous Leishmania donovani subspecies from Sudan, Bangladesh, or Morocco and incorporating 2-ME instead of trypsin in the antigen processing step, a threefold increase in titer was attained in sera from the respective areas where VL is endemic. 2-ME-processed antigen suspensions maintained stability at 4 degrees C for up to 9 months, as evidenced by the absence of autoagglutination and the reproducibility of DAT readings with standard sera. The specificity of DAT was further improved by supplementation of the sample diluent with 0.03 M urea and incubation of the test plates at 37 degrees C for 1 h.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
16.
A-kinase anchoring proteins (AKAPs) constitute a family of scaffolding proteins that bind the regulatory subunits of protein kinase A (PKA). AKAP binding to PKA regulates the phosphorylation of various proteins, some of which have been implicated in synaptic plasticity and memory consolidation. Here we show that the regulatory subunits of PKA are colocalized with AKAP150 (an AKAP isoform that is expressed in the brain) in the lateral amygdala (LA) and that infusion to the LA of the peptide St-Ht31, which blocks PKA anchoring onto AKAPs, impairs memory consolidation of auditory fear conditioning. 相似文献
17.
Determinants of the effect of estrogen on the progression of subclinical atherosclerosis: Estrogen in the Prevention of Atherosclerosis Trial 总被引:1,自引:0,他引:1
Karim R Mack WJ Lobo RA Hwang J Liu CR Liu CH Sevanian A Hodis HN 《Menopause (New York, N.Y.)》2005,12(4):366-373
OBJECTIVE: To determine the extent to which the estrogen-induced changes in lipids and markers of carbohydrate metabolism explain the beneficial effect of estrogen therapy on the progression of carotid artery intima-media thickness (IMT) in postmenopausal women. DESIGN: A randomized, double-blind, placebo-controlled, single-center trial enrolling 222 postmenopausal women 45 years and older without cardiovascular disease and with low-density lipoprotein (LDL) cholesterol levels of 3.37 mmol/L or greater (> or = 130 mg/dL). Intervention was unopposed micronized 17beta-estradiol versus placebo. Measurements were made using high-resolution B-mode ultrasonography to measure carotid artery IMT at baseline and every 6 months on-trial. RESULTS: Progression of carotid IMT was inversely related to on-trial high-density lipoprotein (HDL) cholesterol (P = 0.04) and was directly related to on-trial LDL-cholesterol (P = 0.005). Compared with placebo, women randomized to estradiol showed a higher mean on-trial HDL-cholesterol level and a lower mean on-trial LDL-cholesterol level. In contrast, fasting glucose, insulin, and hemoglobin A1C were lowered and insulin sensitivity increased with estradiol therapy, but the changes were not related to carotid IMT progression. On-trial HDL-cholesterol and LDL-cholesterol were significant independent determinants of carotid IMT progression, jointly explaining 30% of the treatment effect of unopposed estrogen on the progression of carotid IMT. CONCLUSION: Unopposed 17beta-estradiol reduced carotid IMT progression in postmenopausal women in part by increasing HDL-cholesterol and decreasing LDL-cholesterol. Although women randomized to estradiol showed improvement in all the markers of carbohydrate metabolism, these factors did not play a significant role in carotid IMT progression. 相似文献
18.
The growth in length and weight of 91 poor urban Bangladeshi infants was monitored at monthly intervals from birth to 1 year. At birth 18%, 22% and 8% were below -2.00 standard deviations of the National Center for Health Statistics (NCHS) height-for-age, weight-for-age and weight-for-height, respectively and at 1 year the percentages were 40%, 40% and 7%. Infant weights over the first 6 months associated positively with both mother's BMI and percentage body fat. Higher mean infant weights from 6 to 12 months were associated with both higher educational status of the mother and monthly family income and the latter two variables provided the best model for predicting weight velocity from birth to 12 months. Internal Z-scores, corrected for day of measurement, provided clear evidence of catch-up/catch-down over the first 6 months with heavier and longer babies at birth showing catch-down while lighter and shorter babies demonstrated catch-up. Infants' weights were almost three times more variable than lengths. Monthly incremental variability of both infant weight and length increased sharply from 6 to 12 months with weight showing significantly more variability. The correlations of birth weight and length with subsequent distances and monthly increment revealed that the first 6 months were dominated by catch-up and catch-down but during the latter half of the year the growth phenomena were influenced mainly by earlier intra-uterine or genetic effects. 相似文献
19.
The effect of adriamycin (10 mg/kg body weight) on the rat incisor was investigated in 8-day-old animals at 9 days and 14 days after subcutaneous injection. The drug produced changes that were still present 14 days after administration. During this time osteodentin formation, which appeared to be the principal effect of the drug on the incisors, occurred to such an extent that in some regions of the teeth the pulp chamber was almost completely occluded. The formation of osteodentin began at the periphery of the pulp and gradually advanced towards the central region. Moreover, in some sections of the incisor the dentin layer was greatly reduced to a thin superficial layer, while osteodentin surrounded most of the pulp chamber. Cells that appeared to be differentiated pulp-mesenchymal cells were found within as well as on the surface of the irregular osteodentin matrix. Since this drug has been used in the treatment of childhood osteosarcomas, the possibility of dental abnormalities developing in these children cannot be overlooked. 相似文献
20.
Groups of wild-caught Culex quinquefaciatus Say, previously tested for the presence of hepatitis B surface antigen (HBsAg), were tested for the presence of hepatitis B e antigen (HBeAg). This antigen was detected at low levels in blood-fed, half-gravid, and gravid groups. A colony of Cx. quinquefasciatus was established in the laboratory and tested for the persistence of HBsAg and HBeAg. Five days after feeding on blood infected with HBsAg and HBeAg, 9 of 20 (45%) pools of Cx. quinquefasciatus were HBeAg-positive and 5 of 20 (25%) pools were HBeAg-positive; low levels of HBsAg and HBeAg were still detectable 28 d after the infective meal in 2 of 20 (10%) and 1 of 20 (5%) pools, respectively. A crude protease extract was prepared from colony mosquitoes, and the effect of this extract on HBsAg and HBeAg present in human serum was tested in vitro. After 20 h, tests for both antigens were still strongly positive. Low levels of HBsAg were detected in ovaries 7 d after infection. Salivary glands were HBsAg- and HBeAg-negative. 相似文献