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   1896篇
  免费   108篇
  国内免费   119篇
耳鼻咽喉   18篇
儿科学   54篇
妇产科学   36篇
基础医学   181篇
口腔科学   31篇
临床医学   327篇
内科学   351篇
皮肤病学   40篇
神经病学   103篇
特种医学   186篇
外科学   251篇
综合类   72篇
一般理论   1篇
预防医学   110篇
眼科学   60篇
药学   213篇
中国医学   13篇
肿瘤学   76篇
  2023年   18篇
  2022年   35篇
  2021年   55篇
  2020年   48篇
  2019年   71篇
  2018年   73篇
  2017年   55篇
  2016年   55篇
  2015年   63篇
  2014年   74篇
  2013年   134篇
  2012年   108篇
  2011年   126篇
  2010年   98篇
  2009年   107篇
  2008年   81篇
  2007年   120篇
  2006年   76篇
  2005年   59篇
  2004年   52篇
  2003年   43篇
  2002年   47篇
  2001年   37篇
  2000年   27篇
  1999年   19篇
  1998年   44篇
  1997年   34篇
  1996年   33篇
  1995年   32篇
  1994年   25篇
  1993年   20篇
  1992年   13篇
  1991年   13篇
  1990年   17篇
  1989年   26篇
  1988年   36篇
  1987年   18篇
  1986年   9篇
  1985年   16篇
  1984年   6篇
  1983年   9篇
  1982年   8篇
  1981年   9篇
  1980年   9篇
  1979年   7篇
  1978年   5篇
  1976年   5篇
  1975年   9篇
  1958年   14篇
  1955年   4篇
排序方式: 共有2123条查询结果,搜索用时 15 毫秒
91.
Although no ionizing radiation is involved, patients undergoing magnetic resonance imaging (MRI) are exposed to powerful static magnetic fields, magnetic field gradients, and radio-frequency fields that may be potentially damaging. Our study aims to document the effect of MRI imaging sequences on early murine embryo development (two-cell to blastocyst stage) in vitro. Two-cell murine embryos were exposed to various lengths of MRI using pulse sequences employed in present day clinical imaging. Early murine embryo development was documented in vitro, and blastocyst development rates were computed for both the control and exposed groups. There were no significant differences detected in the rate of blastocyst formation between the control groups and the embryos exposed to MRI.  相似文献   
92.
Objective : Understanding patients' and their parents' perceptions towards asthma medication is important in developing strategies to ensure patient compliance. In this study, parents' perceptions towards their children's use of inhaled medication for asthma treatment were evaluated.
Methodology : A questionnaire was administered by interviewing parents of 210 asthmatic children attending the Department of Paediatrics, National University Hospital.
Results : Our results showed that 76/210 (36%) of parents either felt opposed to inhaler therapy and/or preferred oral medications. The main reasons for their reluctance to use inhalers were related to fear of dependence, side effects and overdosage, and the child's dislike for inhalers. A third of these parents felt that inhalers were only indicated for very severe asthma.
Conclusions : We conclude that a significant proportion of parents have reservations regarding the use of inhalers for the treatment of asthma. These factors should be taken into consideration when planning an effective asthma education programme.  相似文献   
93.
Objective : To assess the relationship between the subtypes of hypertension in pregnancy and subsequent neonatal haematology.
Methodology : Retrospective review of the haematology of newborns of hypertensive mothers at a tertiary neonatal unit
Results : Over a 2 year period. 249 infants had full blood examinations. Nineteen (7.6%) were neutropenic and 35 (14.1%) thrombocytopenic, including 11 (4.4%) who were both neutropenic and thrombocytopenic. Neutropenia occurred only in infants whose mothers had severe pre-eclampsia and eclampsia or pre-eclampsia with pre-existing hypertension, whereas thrombocytopenia complicated all maternal hypertension subtypes. Two (10%) of the neutropenic infants developed nosocomial infection while seven (20%) of the thrombocytopenic infants bled. Thirteen (68%) of the neutropenic infants compared with 15 (43%) of the thrombocytopenic infants developed their haematological abnormality within 24 h of birth. All but two infants developed the haematological abnormality by the 5th day of life.
Conclusions : Although haematological abnormalities in infants born to hypertensive mothers are uncommon, serious neonatal complications can occur and therefore early haematological screening of these infants is recommended.  相似文献   
94.

Objective

Previous studies have shown that a subgroup of children with suspected (central) auditory processing disorder (SusCAPD) have insufficient ability to use binaural cues to benefit from spatial processing. Thus, they experience considerable listening difficulties in challenging auditory environments, such as classrooms. Some researchers have also indicated the probable role of binaural temporal fine structure (TFS) in the perceptual segregation of target signal from noise and hence in speech perception in noise. Therefore, in the present study, in order to further investigate the underlying reason for listening problems against background noise in this group of children, their performance was measured using binaural TFS sensitivity test (TFS-LF) as well as behavioral auditory lateralization in noise test, both of which are based on binaural temporal cues processing.

Methods

Participants in this analytical study included 91 children with normal hearing and no listening problems and 41 children (9–12 years old) with SusCAPD who found it challenging to understand speech in noise. Initially, the ability to use binaural TFS was measured at three frequencies (250, 500 and 750 Hz) in both the groups, and the results of preliminary evaluations were compared between normal children and those with SusCAPD who participated in the study. Thereafter, the binaural performance of the 16 children with SusCAPD who had higher thresholds than the normal group at all three frequencies tested in TFS-LF test was examined using the lateralization test in 7 spatial locations.

Results

Total 16 of the 41 children with SusCAPD who participated in this study (39%) showed poor performance on the TFS-LF test at all three frequencies, compared to both normal children and other children in the APD group (p < 0.05). Furthermore, children in the APD group with binaural TFS coding deficits at all three frequencies revealed significant differences in the lateralization test results compared to normal children (p < 0.05).

Conclusion

Findings of the current study demonstrated that one of the underlying causes for the difficulty understanding speech in noisy environments experienced by a subgroup of children with SusCAPD can be the reduced ability to benefit from binaural TFS information. This study also showed that a reduced ability to use binaural TFS cues in the group of children with SusCAPD was accompanied by reduced binaural processing abilities in the lateralization test which also admit the presence of binaural temporal processing deficits in this group of children.  相似文献   
95.
96.
Percutaneous transluminal angioplasty with stenting (PTAS) has become a treatment option for severe carotid stenosis. The goal of our study was to determine prospectively neurocognitive outcome 6 months after unilateral stent-protected carotid angioplasty. Twenty consecutive patients who underwent stent-protected angioplasty for symptomatic (n=9) or asymptomatic (n=11) high-grade carotid stenosis were investigated and compared to an age and disease matched control group. Patients were administered preprocedurally and 6 months postprocedurally a battery of neuropsychological tests. We used reliable change indices methodology in order to control for practice and statistical effects unrelated to intervention. We found no cognitive change in approximately 90% of patients and cognitive improvement in approximately 10% of patients for concentration and attention variables. We further found no cognitive change in 61% of patients, cognitive improvement in 11% of patients and cognitive deterioration in 28% of patients for psychomotor speed. No cognitive change in 94% of patients and cognitive deterioration in 6% of patients was found for sustained attention; no cognitive change in 80% of patients, cognitive improvement in 15% of patients and cognitive deterioration in 5% of patients was found for verbal fluency; no cognitive change in 100% of patients was found for interference (Stroop test): no cognitive change in 95% of patients, cognitive improvement in 5% of patients was found for interference (c.I. test), respectively.Our study showed that 6 months after PTAS cognitive functioning did not change in most patients significantly. For some patients, however, significant improvement or deterioration in single neurocognitive domains can be expected. The reasons for these changes are unclear but may depend on variable type; magnitude of microemboli production; right vs. left cerebral vasculature, respectively.  相似文献   
97.
98.
Although glycine is a major inhibitory transmitter in the mammalian CNS, the role of glycinergic neurons in defined neuronal circuits remains ill defined. This is due in part to difficulties in identifying these cells in living slice preparations for electrophysiological recordings and visualizing their axonal projections. To facilitate the morphological and functional analysis of glycinergic neurons, we generated bacterial artificial chromosome (BAC) transgenic mice, which specifically express enhanced green fluorescent protein (EGFP) under the control of the promotor of the glycine transporter (GlyT) 2 gene, which is a reliable marker for glycinergic neurons. Neurons expressing GlyT2-EGFP were intensely fluorescent, and their dendrites and axons could be visualized in great detail. Numerous positive neurons were detected in the spinal cord, brainstem, and cerebellum. The hypothalamus, intralaminar nuclei of the thalamus, and basal forebrain also received a dense GlyT2-EGFP innervation, whereas in the olfactory bulb, striatum, neocortex, hippocampus, and amygdala positive fibers were much less abundant. No GlyT2-EGFP-positive cell bodies were seen in the forebrain. On the subcellular level, GlyT2-EGFP fluorescence was colocalized extensively with glycine immunoreactivity in somata and dendrites and with both glycine and GlyT2 immunoreactivity in axon terminals, as shown by triple staining at all levels of the neuraxis, confirming the selective expression of the transgene in glycinergic neurons. In slice preparations of the spinal cord, no difference between the functional properties of EGFP-positive and negative neurons could be detected, confirming the utility of visually identifying glycinergic neurons to investigate their functional role in electrophysiological studies.  相似文献   
99.
100.
Fertility and contraceptive issues after kidney transplantation in women   总被引:4,自引:0,他引:4  
PURPOSE: Our purpose was to investigate reproductive performance among kidney transplant recipients. MATERIALS AND METHODS: We studied 126 kidney transplanted women 15 to 68 years of age including 33 who were single and 93 who were married. RESULTS: Infertility was seen in 10.4% of those who desired pregnancy, a rate similar to the general population. The most common method of contraception was coitus interruptus (56%), 22% of patients had tubal ligation, 6% had husbands who had vasectomies, 14% were using condoms, and only 2% used oral contraceptives. Among 33 pregnancies, 16 were unintended (48.5%). Most of the patients with unwanted pregnancy were using coitus interruptus (93.7%). In the group with unintended pregnancy, abortion was induced in three, spontaneous abortion or intrauterine fetal death occurred in six, and only seven pregnancies resulted in a live birth (43.7%). CONCLUSION: Kidney transplantation greatly improves fertility, so those who do not desire pregnancy should be protected by an effective method of contraception.  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