全文获取类型
收费全文 | 25954篇 |
免费 | 1792篇 |
国内免费 | 107篇 |
专业分类
耳鼻咽喉 | 273篇 |
儿科学 | 724篇 |
妇产科学 | 580篇 |
基础医学 | 3938篇 |
口腔科学 | 597篇 |
临床医学 | 2391篇 |
内科学 | 5679篇 |
皮肤病学 | 621篇 |
神经病学 | 2906篇 |
特种医学 | 731篇 |
外科学 | 2882篇 |
综合类 | 148篇 |
一般理论 | 15篇 |
预防医学 | 2241篇 |
眼科学 | 534篇 |
药学 | 1605篇 |
1篇 | |
中国医学 | 106篇 |
肿瘤学 | 1881篇 |
出版年
2024年 | 30篇 |
2023年 | 223篇 |
2022年 | 374篇 |
2021年 | 838篇 |
2020年 | 545篇 |
2019年 | 782篇 |
2018年 | 832篇 |
2017年 | 648篇 |
2016年 | 747篇 |
2015年 | 853篇 |
2014年 | 1014篇 |
2013年 | 1273篇 |
2012年 | 2028篇 |
2011年 | 2177篇 |
2010年 | 1183篇 |
2009年 | 1064篇 |
2008年 | 1713篇 |
2007年 | 1757篇 |
2006年 | 1619篇 |
2005年 | 1538篇 |
2004年 | 1403篇 |
2003年 | 1303篇 |
2002年 | 1120篇 |
2001年 | 272篇 |
2000年 | 277篇 |
1999年 | 265篇 |
1998年 | 229篇 |
1997年 | 195篇 |
1996年 | 141篇 |
1995年 | 126篇 |
1994年 | 102篇 |
1993年 | 67篇 |
1992年 | 124篇 |
1991年 | 104篇 |
1990年 | 107篇 |
1989年 | 83篇 |
1988年 | 60篇 |
1987年 | 69篇 |
1986年 | 52篇 |
1985年 | 53篇 |
1984年 | 48篇 |
1983年 | 42篇 |
1982年 | 31篇 |
1981年 | 30篇 |
1980年 | 31篇 |
1979年 | 26篇 |
1975年 | 21篇 |
1973年 | 38篇 |
1972年 | 23篇 |
1971年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
Claudia Ehringer Mikulaninec 《Patient education and counseling》1987,10(3):253-265
This study sought to contrast mailing a booklet to accomplish preoperative instruction with teaching performed by nurses after hospital admission. Sixty-six patients were studied in a 700-bed medical center and were assigned to three teaching groups and a control group which did not receive teaching. The researcher compared the four groups preoperatively after admission to determine the patients' knowledge and ability to perform surgical exercises, as well as their anxiety levels.
Findings were that patients who received a booklet by mail preadmission learned surgical exercises equally well compared to patients taught postadmission, and mastered significantly more exercise behaviors than those receiving no instruction. No statistical difference in anxiety level was found among groups. One may infer that mailing preadmission material should be considered as an effective teaching mode and alternative to postadmission instruction. 相似文献
62.
Jack Yamuy John K. Engelhardt Francisco R. Morales Michael H. Chase 《Brain research》1992,570(1-2):300-306
The objective of this study was to determine whether the aging process influences the changes in the electrophysiological properties of motoneurons that occur as a consequence of axotomy. Accordingly, using intracellular recording and stimulating techniques, the basic electrical properties of control (unaxotomized) and axotomized spinal cord motoneurons of aged cats were determined. Compared with control motoneurons, axotomized motoneurons exhibited increases in input resistance (Rin), membrane time constant (τb) and the equalizing time constant (τc). While the electrotonic length (L) remained unchanged, axotomy induced a decrease in the total cell capacitance (Ccell. The post-axotomy reduction of Ccell indicates that the motoneuron surface area was reduced and the increased membrane time constant indicates that there was an increase in membrane resistivity (Rm). The post-axotomy conservation of L accompanied by an increase in Rm suggests that aged axotomized motoneurons undergo geometrical changes. Furthermore, calculations based on cable theory suggest that the diameter of the equivalent cylinder (d) decreased following axotomy, whereas the equivalent cylinder length (l) remained unaffected. It is concluded that axotomy produces significant alterations in the soma-dendritic portion of aged spinal motoneurons, as indicated by the changes found in their passive electrophysiological properties, and that the pattern of the response that occurs in axotomized motoneurons of adult cats is also present in axotomized motoneurons of aged animals. 相似文献
63.
Superficial bladder cancer is one of the few solid human malignancies in which immunotherapy has been proved to be effective. Bacillus Calmette-Guérin was the vaccine which opened the door for this innovative approach. In an era of remarkable achievements in biotechnology, it is truly amazing that this throwback to the Stone Age of tumor immunology has not yet been replaced by a more (or equally) effective substitute. Potential candidates are already on the horizon and deserve a comprehensive evaluation. They must show not only that they are devoid of significant adverse effects but that they possess, beyond a doubt, superior antineoplastic activity. Even more remarkable is that one of the oldest vaccines still in use could emerge in a new role as an effective antineoplastic agent. Bacillus Calmette-Guérin has demonstrated an uncanny capacity for effectiveness as therapy for human diseases. Its protective effect against tuberculosis is well recognized, and its contribution to cancer therapy is widely known. A new and increasing repertoire has recently been presented: two separate groups of researchers have employed the vaccine successfully as a vehicle to express antigen-encoded genes from other pathogens. The exciting aspect of these recent studies resides in the demonstration that the altered vaccine is able to induce humoral and cell-mediated immune responses to the recombinant antigens, including the human immunodeficiency virus (HIV). Thus, BCG once more attracts enormous interest from the scientific community for its versatility and potential as a therapeutic agent. 相似文献
64.
Henryk Barthel Michael Wiener Claudia Dannenberg Simone Bettin Bernhard Sattler Wolfram H. Knapp 《European journal of nuclear medicine and molecular imaging》1997,24(10):1245-1252
This study addresses the question of whether the normal range for distribution of local cerebral blood flow (lCBF) in adults
can be transferred to the 4- to 15-year-old age group. Twenty-three children (age: 4–15 years; mean 11±3 years, group I) and
10 adults (age: 27–56 years; mean 45±10 years, group II) without evidence of cerebrovascular disease or other brain diseases
underwent technetium-99m ethyl cysteinate dimer single-photon emission tomography. Counts in cortical and subcortical regions
of interest (ROIs) were related to those in cerebellar ROIs (= 100%). Relative cortical activity in group I exceeded that
in group II, particularly in left parietal (107.6%±9.8% vs 84.1%±12.4%), left frontal (97.7%±6.7% vs 79.4%±8.9%) and left
temporal areas (99.7%±7.4% vs 84.9%±10.1%) and in the cingulate cortex (112.1%±9.1% vs 95.9%±10.1%, P<0.05). Cerebral activity uptake per injected dose was inversely correlated with age in 19 children of group I (r = –0.77, P<0.001). In group I, there was also an inverse correlation between age and the relative local count density in the parietal
(r = –0.42 to –0.57), frontal (r = –0.48), temporal (r = –0.42 to –0.58) and occipital cortex (r = –0.44). In these cortical regions relative counts differed when subgroups of children aged 4–10 and 11–15 years were analysed.
It is concluded that there are systematic differences between 4- to 15-year-old children and adults with regard to normal
lCBF. Diagnostic use of perfusion agents has to consider age-adjusted normal flow maps; normal ranges should be determined
separately for the age groups 4–10 and 11–15 years.
Received 23 March and in revised form 11 July 1997 相似文献
65.
Sporozoites and free circumsporozoite (CS) protein were stained immunoenzymatically in 1-min saliva samples collected fromAnopheles stephensi mosquitoes infected with eitherPlasmodium berghei orP. falciparum. The number of sporozoites in 1-min saliva-streak samples significantly increased as the salivary gland index rose from 3+ to 4+. ForP. berghei-infected mosquitoes from which saliva had been collected before 30 days postfeed, the median sporozoite counts for 3+ and 4+ gland indexes were 4.5 and 116, respectively. ForP. falciparum-infected mosquitoes, the median counts obtained in two experiments were 4.5 and 14.5 (3+) and 97 and 107 (4+), respectively. The frequency of sporozoite detection in the saliva of mosquitoes containing <100 salivary-gland sporozoites was low (0.1), whereas that in the saliva of mosquitoes with >100 sporozoites was high (0.96). In highly infected 4+P. berghei-infected mosquitoes from which saliva had been collected after 30 days postinfection, both the volume of saliva collected and the median number of sporozoites recovered decreased significantly. 相似文献
66.
Claudia Giaroli Gianfranco Riccò Gianni Vecchi Stefano Belli Caterina Bruno Mario Grignoli Silvia Candela Salvatore Minisci Roberto Poletti Guiseppina Venturi Antonio Ziccardi Pietro Comba 《International archives of occupational and environmental health》1994,66(1):7-11
The present study describes cause-specific mortality of asbestos cement workers in the Emilia Romagna region of Italy. The cohort included workers in ten factories, most of which started operating between 1955 and 1965. Asbestos, mainly chrysotile, constituted 10%–20% of the dry component of the mixture. Crocidolite range between 5% and 50% of total asbestos. Asbestos concentrations up to 44 ff/cc were reported prior to 1975, while in recent years they have usually been below 0–1 ff/cc. The cohort included 3341 workers who had at some time been employed in the ten factories under study. Their mortality experience was compared with that of the population resident in Emilia Romagna. Vital status was ascertained at 1989. Seventy-three subjects were lost to followup (2.2%). Mortality from all causes and from all types of cancer was increased in the cohort. Malignant neoplasms of the respiratory tract showed a significant increase (SMR: 134; 90% confidence interval: 101–175; 40 observed) due to lung cancer (SMR: 124; 90% confidence interval: 91–166; 33 observed) and neoplasms of the pleura, mediastinum, and other parts of the respiratory tract (SMR: 602; 90% confidence interval 237–1267; 5 observed). The discrepancy between observed and expected mortality mainly concerned subjects with at least 20 years of employment in the factories. Five more cases of histologically confirmed mesothelioma occurred after the end of follow-up. 相似文献
67.
The prolactin gene is expressed in the hypothalamic-neurohypophyseal system and the protein is processed into a 14-kDa fragment with activity like 16-kDa prolactin. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
68.
Do weekly and fast-rotating shiftwork schedules differentially affect duration and quality of sleep?
F. M. Fischer Antonio Castro Bruni Adelaide Berwerth Claudia Roberta Castro Moreno Rosaneli Lima Fernandez Claudia Riviello 《International archives of occupational and environmental health》1997,69(5):354-360
Characteristics of shiftwork schedules can have distinct impacts on workers’ sleep. This report presents comparisons of the
effects of two different shiftwork schedules on duration and quality of the main sleep episodes in comparable worker populations
at two different petrochemical plants. No significant differences were found for sleep duration in comparing the two plants.
However, within each plant’s shift cycles, morning and night shifts showed shorter sleep durations than all other workdays
and days off. Quality of sleep was perceived as lowest for night shifts of both plant schedules, and of lesser quality for
weekly than for fast-rotating shifts. These results support recommendations for reducing the number of consecutive nights
of shiftwork. However, before recommending any optimal shift schedule, interactions of sleep duration and quality with shift
schedules need much further evaluation.
Received: 18 December 1995/Accepted: 18 July 1996 相似文献
69.
70.