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   4892篇
  免费   180篇
  国内免费   1篇
  5073篇
  2023年   15篇
  2022年   14篇
  2021年   36篇
  2020年   17篇
  2019年   32篇
  2018年   83篇
  2017年   81篇
  2016年   96篇
  2015年   78篇
  2014年   109篇
  2013年   200篇
  2012年   421篇
  2011年   631篇
  2010年   279篇
  2009年   77篇
  2008年   416篇
  2007年   389篇
  2006年   333篇
  2005年   303篇
  2004年   233篇
  2003年   231篇
  2002年   171篇
  2001年   67篇
  2000年   147篇
  1999年   76篇
  1998年   50篇
  1997年   13篇
  1996年   12篇
  1995年   17篇
  1993年   10篇
  1992年   20篇
  1991年   14篇
  1990年   11篇
  1989年   12篇
  1988年   10篇
  1987年   17篇
  1985年   20篇
  1984年   22篇
  1982年   16篇
  1980年   17篇
  1979年   16篇
  1978年   13篇
  1977年   9篇
  1976年   18篇
  1975年   13篇
  1974年   18篇
  1973年   9篇
  1971年   12篇
  1970年   9篇
  1967年   9篇
排序方式: 共有5073条查询结果,搜索用时 15 毫秒
91.
Schizophrenia and other psychotic disorders as well as the delirium caused by abstinence from alcohol and accute state of drunkenness appear at the very top of the list of factors, which are positively correlated with involuntary hospitalization of patients. This is at the same time a confirmation of the data found in literature considering psychosis an essential factor of involuntary hospitalization; the same referring to the male sex was not, however, confirmed by the results obtained in the first and second research period. Regarding the positive correlation between schizophrenia and other psychotic disturbances, dementia, delirium and other cognitive impairments including the delirium caused by abstinence from alcohol and an accute state of drunkenness on the one side and the high rate of involuntary hospitalization on the other, there is no statistically significant difference between the period preceding and the period following the alterations and amendments to the Law on the protection of patients with mental disorders.  相似文献   
92.
In contrast to cold and eurythermal waters, benthic communities of warm brooks in temperate regions have been inadequately studied. In order to investigate the effects of water thermal regime on the benthic communities of warm waters and their relationships with those of cold and eurythermic ones, the macrozoobenthos was studied at eight sites in the Toplica River, and at four sites in its tributary, the Termalni brook. Investigations were carried out seasonally from April 2000 to January 2001. Warm waters of the Termalni brook were characterized by specific macrozoobenthos assemblages that exhibited significant differences to the populations of eurythermal and cold waters of the Toplica River. The dominant taxa in the macrozoobenthos community of warm waters were mainly Gastropoda species. Moreover, benthic communities of warm waters were characterized by lower diversity and greater biomass in comparison with those of cold and eurythermal waters. The gradient of average annual temperatures represented the main ecological factor influencing changes of diversity and biomass along the course of the investigated Termalni brook. Inflow of warm waters at site T6 lead to a decrease in macrozoobenthos abundance and changes in qualitative and quantitative composition of the benthocoenosis of a highland stream, but did not significantly alter diversity.  相似文献   
93.
A total of 835 patients with symptoms of chronic prostatitis syndrome and no evidence of structural or functional lower genitourinary tract abnormalities were examined in a three year period at the Outpatient Department for Urogenital Infections, University Hospital for Infectious Diseases "Dr. Fran Mihaljevi?" Zagreb, Croatia. Disease etiology was determined in 482 (57.72%) patients. Chlamydia trachomatis was proved to be the causative pathogen in 161 patients, Trichomonas vaginalis in 85, Escherichia coli in 68, Enterococcus in 51, Proteus mirabilis in 20, Klebsiella pneumoniae in 9, Streptococcus agalactiae in 15, Ureaplasma urealyticum in 49 patients with chronic prostatitis. Other patients had mixed infection. In 257 (53.32%) of 482 patients, the inflammatory finding (>10 WBCs/hpf) was found in EPS or VB3. Normal WBCs/hpf (<10) was found in 103 (63.98%) of 161 patients with symptoms of chronic prostatitis in whom C. trachomatis was detected in EPS or VB3, in 50 (58.82%) of 85 patients in whom Trichomonas vaginalis was isolated, and in 23 (46.94%) of 49 patients in whom Ureaplasma urealyticum was isolated.  相似文献   
94.
The aim of this study was to assess the quality of life children after cardiac surgery for congenital heart disease (CHD) and to compare these results with healthy children. To assess the quality of life children after surgery for CHD we performed a cross-sectional study of 114 patients who were patients at the Department of Paediatrics in Tuzla, between the ages of 2 and 18 years, of both sexes, and with one of their parents. We used the "PedsQL 4.0 Generic Core Scales", with both child self-report and parent proxy-reports. By self assessment, the PedsQL total scores for quality of life were statistically significantly different between children after cardiac surgery for ages 13 to 18 years and healthy children, while by parent report PedsQL total scores were statistically significantly different between children after cardiac surgery for ages 5 to 7 years and healthy children. By self assessment, children after cardiac surgery for ages from 5 to 7 and 13 to 18 years reported that they have a statistically significantly lower quality of life in the segment school functioning compared to the healthy children. By parental assessment, children after cardiac surgery for ages 2 to 4, 5 to 7 and 8 to 12 years have a statistically significantly lower quality of life in the segments of physical and psychosocial health, emotional, social and school functioning. The results of our study indicate that children after cardiac surgery for CHD by self and parent assessment have a lower quality of life than healthy children.  相似文献   
95.
The influence of phytoestrogens (genistein and coumestrol) and mycoestrogen (zearalenone) on insulin secretion, liver insulin receptors and some aspects of lipid and carbohydrate metabolism were investigated in this study. Ovariectomized rats were injected s.c. with the above mentioned compounds in the amount of 1 mg for three days. Coumestrol and zearalenone caused a significant increase in uterus weight, similar to the effects observed after estrone action, while this effect was not observed after the genistein injection. Blood insulin level was not changed after phyto- or mycoestrogen treatment. However, coumestrol and genistein significantly decreased the binding capacity of liver insulin receptors. These changes corresponded with alterations in glucose and free fatty acids profiles in blood, as well as with glycogen content in liver. The effects observed after genistein and coumestrol injections differed from those noticed in rats treated with zearalenone or estrone. On the basis of these results we conclude that metabolic effects of high doses of coumestrol and genistein in ovariectomized rats are partly mediated by changes in insulin sensitivity of the liver and that the action of plant estrogens on metabolism is, at least to the some degree, independent of their estrogen activity.  相似文献   
96.
Double tooth     
The form of primary and permanent teeth can differ morphologically from that which is considered normal, completely or in some parts. The changes in tooth form can be hereditary or caused by some disease or trauma. Fusion is a union of one or more teeth during development. Gemination means that two separate morphological units were created by division of the tooth germ. The intention of this study was to state the prevalence of double teeth (fusion and gemination) among the persons tested, as to gender, distribution in the maxilla or mandible, and whether the anomaly occurred bilaterally or unilaterally. The results of this investigation have shown that in a total of examined 3,517 plaster models, a prevalence of double teeth was 0.2%. 57.2% of them were fusioned and 42.9% geminated.  相似文献   
97.
A Bayesian framework for combining gene predictions   总被引:2,自引:0,他引:2  
MOTIVATION: Gene identification and gene discovery in new genomic sequences is one of the most timely computational questions addressed by bioinformatics scientists. This computational research has resulted in several systems that have been used successfully in many whole-genome analysis projects. As the number of such systems grows the need for a rigorous way to combine the predictions becomes more essential. RESULTS: In this paper we provide a Bayesian network framework for combining gene predictions from multiple systems. The framework allows us to treat the problem as combining the advice of multiple experts. Previous work in the area used relatively simple ideas such as majority voting. We introduce, for the first time, the use of hidden input/output Markov models for combining gene predictions. We apply the framework to the analysis of the Adh region in Drosophila that has been carefully studied in the context of gene finding and used as a basis for the GASP competition. The main challenge in combination of gene prediction programs is the fact that the systems are relying on similar features such as cod on usage and as a result the predictions are often correlated. We show that our approach is promising to improve the prediction accuracy and provides a systematic and flexible framework for incorporating multiple sources of evidence into gene prediction systems.  相似文献   
98.
The selenium (Se) contents in common cereals in endemic and nonendemic areas in Serbia are very low. Plasma Se levels of both patients and healthy subjects, were also low, reflecting low Se intakes. Patients with Balkan endemic nephropathy (BEN) had significantly lower (p<0.05) plasma Se levels than healthy individuals, both from regions close to endemic areas, and from Belgrade. Mean plasma Se of BEN patients was slightly but insignificantly higher in samples taken immediately after dialysis than in those taken before, suggesting that very little of the Se present in plasma is dialyzable. Plasma SeGSH-Px activities before and after hemodialysis in both BEN and Nonendemic chronic renal failure (NCRF) patients were not significantly different, but BEN patients had lower enzyme activities than those with NCRF and healthy controls. In BEN patients, a significant correlation between plasma Se and SeGSH-Px activity was found. NCFR patients were with diagnoses: TBC of kidneys, chronic glomerulonephritis, chronic pyelonephritis, and polycystic kidneys.  相似文献   
99.
100.
We present a rectangle-based segmentation algorithm that sets up a graph and performs a graph cut to separate an object from the background. However, graph-based algorithms distribute the graph's nodes uniformly and equidistantly on the image. Then, a smoothness term is added to force the cut to prefer a particular shape. This strategy does not allow the cut to prefer a certain structure, especially when areas of the object are indistinguishable from the background. We solve this problem by referring to a rectangle shape of the object when sampling the graph nodes, i.e., the nodes are distributed non-uniformly and non-equidistantly on the image. This strategy can be useful, when areas of the object are indistinguishable from the background. For evaluation, we focus on vertebrae images from Magnetic Resonance Imaging (MRI) datasets to support the time consuming manual slice-by-slice segmentation performed by physicians. The ground truth of the vertebrae boundaries were manually extracted by two clinical experts (neurological surgeons) with several years of experience in spine surgery and afterwards compared with the automatic segmentation results of the proposed scheme yielding an average Dice Similarity Coefficient (DSC) of 90.97±2.2%.  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