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   1162篇
  免费   65篇
  国内免费   10篇
耳鼻咽喉   14篇
儿科学   45篇
妇产科学   12篇
基础医学   128篇
口腔科学   49篇
临床医学   88篇
内科学   302篇
皮肤病学   23篇
神经病学   92篇
特种医学   138篇
外科学   116篇
综合类   29篇
一般理论   1篇
预防医学   49篇
眼科学   8篇
药学   80篇
中国医学   1篇
肿瘤学   62篇
  2023年   5篇
  2022年   15篇
  2021年   28篇
  2020年   9篇
  2019年   5篇
  2018年   20篇
  2017年   12篇
  2016年   18篇
  2015年   21篇
  2014年   25篇
  2013年   45篇
  2012年   52篇
  2011年   38篇
  2010年   46篇
  2009年   44篇
  2008年   45篇
  2007年   51篇
  2006年   61篇
  2005年   49篇
  2004年   40篇
  2003年   50篇
  2002年   37篇
  2001年   23篇
  2000年   28篇
  1999年   22篇
  1998年   44篇
  1997年   32篇
  1996年   28篇
  1995年   18篇
  1994年   27篇
  1993年   28篇
  1992年   21篇
  1991年   22篇
  1990年   11篇
  1989年   23篇
  1988年   22篇
  1987年   15篇
  1986年   17篇
  1985年   11篇
  1984年   11篇
  1983年   8篇
  1982年   11篇
  1981年   13篇
  1980年   15篇
  1979年   6篇
  1978年   6篇
  1977年   9篇
  1976年   14篇
  1973年   7篇
  1972年   5篇
排序方式: 共有1237条查询结果,搜索用时 15 毫秒
1.
OBJECTIVE: Nocturnal enuresis is a common pediatric problem, the etiology of which is unclear. In recent years, various studies have been published stating that children with nocturnal enuresis exhibit growth and skeletal maturation retardation. METHODS: In this cross-sectional study, we included 27 patients (16 boys, 11 girls) between the ages of 6 and 14 years who had presented with primary nocturnal enuresis (PNE) complaints. We included in the evaluation 19 healthy subjects (12 boys, 7 girls), who were the siblings of the children with PNE, as the control group. RESULTS: The patients in both groups were similar in chronological age, bone age, height and weight, with no significant difference between groups (P>0.05). CONCLUSION: The two groups in our study consisted of the same genetic background. Thus, our results were found to be different from the previous studies. We have concluded that there is no direct relationship between enuresis nocturnal and skeletal maturation.  相似文献   
2.
3.
4.
Summary Phosphonacetyl-l-aspartate (PALA), an inhibitor of aspartate transcarbamylase that depletes uridine nucleotide pools, selectively potentiates the antitumor activity of 5-fluorouracil (5-FU) in preclinical models. Due to the promising results we obtained using PALA/5-FU in colorectal cancer, we performed a phase II trial in patients presenting with advanced pancreatic cancer. PALA was given intravenously at 250 mg/m2 on day 1, followed 24 h later by 2,600 mg/m2 5-FU given by 24-h infusion. Treatments were repeated weekly. A total of 41 patients who had not previously undergone chemotherapy were entered in the trial; of these, 35 were evaluable for response. Toxicity was generally mild to moderate; neurotoxicity (13/35) and diarrhea (8/35) predominated. Among the 35 patients, 1 achieved a complete response and 4, a partial remission, for an overall response rate of 14%. The median survival was 5.1 months. Pretreatment with PALA alone was not sufficient to enhance the activity of 5-FU in pancreatic cancer.Supported in part by grant CA 06927 from the National Cancer Institute  相似文献   
5.
Pre-clerking of all patients undergoing elective general surgical operations was introduced at our hospital in an attempt to reduce an unacceptably high operation cancellation rate. A prospective audit has been performed on the effect of this policy on the cancellation rate. Before the introduction of pre-clerking there was a marked seasonal variation in the number of patients who failed to attend for surgery, which could be explained by absence on holiday. This seasonal variation disappeared after the start of pre-clerking clinics, but there has been no reduction in the number of cancellations for medical reasons.  相似文献   
6.
X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG repeat expansion in the first exon of the androgen receptor (AR) gene. Disease-associated alleles (37-66 CAGs) change in length when transmitted from parents to offspring, with a significantly greater tendency to shift size when inherited paternally. As transgenic mice carrying human AR cDNAs with 45 and 66 CAG repeats do not display repeat instability, we attempted to model trinucleotide repeat instability by generating transgenic mice with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions in their genomic context. Studies of independent lines of AR YAC transgenic mice with CAG 45 alleles reveal intergenerational instability at an overall rate of approximately 10%. We also find that the 45 CAG repeat tracts are significantly more unstable with maternal transmission and as the transmitting mother ages. Of all the CAG/CTG repeat transgenic mice produced to date the AR YAC CAG 45 mice are unstable with the smallest trinucleotide repeat mutations, suggesting that the length threshold for repeat instability in the mouse may be lowered by including the appropriate flanking human DNA sequences. By sequence-tagged site content analysis and long range mapping we determined that one unstable transgenic line has integrated an approximately 70 kb segment of the AR locus due to fragmentation of the AR YAC. Identification of the cis - acting elements that permit CAG tract instability and the trans -acting factors that modulate repeat instability in the AR YAC CAG 45 mice may provide insights into the molecular basis of trinucleotide repeat instability in humans.   相似文献   
7.
8.
Certain B and T cell lines respond to activation signals, e.g.through the antigen receptor, by undergoing apoptotlc cell death.In T cells it has been recently shown that TCR-mediated apoptosisinvolves APO-1/Fas (CD95) receptor-ligand interaction. To investigatewhether the TCR-CD3 complex can trigger alternative apoptosispathways we generated subclones of the T cell line Jurkat whichwere completely resistant towards APO-1-mediated apoptosis.These JurkatR cells differed phenotypically from sensitive parentalJurkatS cells only by the lack of APO-1 protein expression.Although JurkatR cells responded normally to anti-CD3 stimulationby expression of APO-1 ligand they failed to undergo anti-CD3-inducedapoptosis. Thus, in Jurkat cells APO-1 -mediated apoptosis wasthe main, and might be the only, mechanism for anti-CD3-inducedcell death. However, BL-60 B cells, highly sensitive to anti-IgM-inducedapoptosis, did not use the APO-1 receptor-ligand system becausethey failed to express APO-1 ligand mRNA. Taken together, ourresults suggest that malignant T and B cell lines may use APO-1receptor-ligand-dependent and -independent antigen receptor-inducedapoptosis pathways respectively. Similarly, differential pathwaysmay be used by T and B cell subsets.  相似文献   
9.
Monoclonal antibodies were raised against pregnancy-associated endometrial alpha 1-globulin (alpha 1-PEG), a 32 KD insulin-like growth factor binding protein (IGF-BP), which represents a major secretory product of the human decidualized endometrium during pregnancy. This class of IGF-BP has been implicated in the modulation of action, inhibitory and stimulatory, of insulin-like growth factors. Immunization with the protein purified from pregnancy endometrium resulted after myeloma fusion in the isolation of six hybridoma clones and the antibodies produced were characterized. The Ka of the antibodies ranged between 4.75 x 10(9) M-1 and 0.7 x 10(8) M-1. In Western blots all monoclonal antibodies reacted with purified protein of molecular weight 32 KD and specifically detected this IGF-BP species in culture medium and cytosolic extracts of pregnancy endometrium and amniotic fluid. The monoclonal antibodies appear to define three epitope-bearing regions as evidenced by their reactivity to polypeptide fragments of the protein. After synthesis and secretion by tissue explants in vitro the protein is susceptible to cleavage into fragments possessing different monoclonal antibody-defined reactivity. Employing immunohistochemical techniques the protein was principally localized to decidual cells in tissue sections of pregnancy endometrium and solely to these cells after enzymic digestion of the tissue. The implications of these results are discussed with respect to potential role of IGF-BP in the action of IGF upon the IGF-1 receptor-bearing populations, including lymphocytes and trophoblast cells, D in the decidua.  相似文献   
10.
BACKGROUND: Patients with brief, complex partial seizures frequently suffer from tiredness and decreased productivity that continue well beyond the postictal period. A possible explanation is that seizures, even when occurring during the day, disrupt sleep the following night. OBJECTIVE: To determine the effect of temporal lobe complex partial seizures on sleep structure and daytime drowsiness. METHODS: Patients with temporal lobe epilepsy were admitted for video-electroencephalography monitoring. All-night polysomnography was recorded under the following 3 conditions: seizure free, seizure during the day before the recording, and seizure during the recording. Percentage of time in each sleep stage, sleep efficiency, and time to first and second rapid eye movement (REM) period were compared for seizure vs control conditions. Daytime drowsiness was also measured, using a modified maintenance of wakefulness test and 2 subjective drowsiness tests. RESULTS: Daytime seizures reduced REM from 18%+/-1% to 12%+/-2% (P = .003). Night seizures reduced REM from 16%+/-1% to 6.8%+/-2% (P<.001). Night seizures also significantly reduced stages 2 and 4 while increasing stage 1 sleep. Night seizures, but not day seizures, significantly reduced sleep efficiency, increased time to first REM period, and increased drowsiness as measured by the maintenance of wakefulness test. CONCLUSIONS: Temporal lobe complex partial seizures decrease REM sleep, particularly when occurring during sleep but also when occurring on the previous day. This may, in part, be responsible for the prolonged impairment of functioning that some patients report following seizures.  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