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   864篇
  免费   60篇
  国内免费   7篇
耳鼻咽喉   2篇
儿科学   47篇
妇产科学   2篇
基础医学   106篇
口腔科学   33篇
临床医学   67篇
内科学   167篇
皮肤病学   20篇
神经病学   95篇
特种医学   108篇
外科学   144篇
综合类   26篇
预防医学   33篇
眼科学   8篇
药学   51篇
中国医学   1篇
肿瘤学   21篇
  2021年   19篇
  2020年   4篇
  2019年   5篇
  2018年   10篇
  2017年   4篇
  2016年   11篇
  2015年   13篇
  2014年   17篇
  2013年   39篇
  2012年   32篇
  2011年   17篇
  2010年   30篇
  2009年   33篇
  2008年   22篇
  2007年   19篇
  2006年   26篇
  2005年   24篇
  2004年   13篇
  2003年   15篇
  2002年   16篇
  2001年   12篇
  2000年   17篇
  1999年   20篇
  1998年   36篇
  1997年   27篇
  1996年   24篇
  1995年   17篇
  1994年   25篇
  1993年   25篇
  1992年   16篇
  1991年   12篇
  1990年   11篇
  1989年   21篇
  1988年   24篇
  1987年   22篇
  1986年   21篇
  1985年   16篇
  1984年   17篇
  1983年   14篇
  1982年   18篇
  1981年   20篇
  1980年   27篇
  1979年   21篇
  1978年   16篇
  1977年   14篇
  1976年   16篇
  1975年   6篇
  1974年   13篇
  1973年   7篇
  1918年   3篇
排序方式: 共有931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.
Myocardial fibrosis can occur as a complication of chronic infection of the heart with Trypanosoma cruzi (Chagas' disease) and can lead to serious disability. To assess whether there might be a direct relationship between intracellular parasitization and subsequent tissue fibrosis in this disease, we tested serum-free conditioned media from cultures of fibroblasts, vascular smooth-muscle cells, and myocardial cells for fibroblast-stimulating activity. Conditioned media from all infected cultures, but not from uninfected cultures, stimulated fibroblast [3H]thymidine incorporation, DNA and protein synthesis, and cell proliferation. Fibroblast-stimulating activity was also detected in extracts of amastigotes but not of trypomastigotes or epimastigotes. We conclude that parasitization of mesenchymal cells, including myocardial cells, results in elaboration of a fibroblast-stimulating factor(s), perhaps of parasite origin. We postulate that this factor may play a role in initiation of myocardial fibrosis in Chagas' disease.  相似文献   
3.
4.
5.
Summary: We report a series of 8 patients with ictal déjà vu. Subdural strip electrocorticographic (ECoG) monitoring localized the ictal epileptogenic focus as follows: right (n = 6) and left (n = 2) mesiotemporal lobe. In all 8 patients, the left hemisphere was dominant for language function based on intracarotid amytal testing. In 6 right-handed patients, ictal déjà vu was associated with a right temporal lobe focus. However, in the 2 left-handed patients, the ictal focus was left temporal lobe. Although ictal déjà vu localizes the epileptic focus to temporal lobe, this experiential phenomenon appears to lateralize to the hemisphere nondominant for handedness.  相似文献   
6.
High serum fluoride (F-) in patients with chronic renal failure (CRF) and end-stage renal disease (ESRD) is associated with risk of renal osteodystrophy and other bone changes. This study was done to determine F- in normal healthy controls and patients with ESRD on haemodialysis (HD) or peritoneal dialysis (PD). Seventeen healthy controls (12 males, 5 females) and 39 ESRD patients on dialysis (17 males, 22 females) were recruited in the study in a community with 47.4 +/- 3.28 microM/l (range 44-51 microM/l) of F- content in drinking water. Control subjects showed a mean serum F- concentration of 1.08 +/- 0.350 microM/l. Males in control group showed slightly higher F- levels (1.15 +/- 0.334, range 0.55-1.9 microM/l) than females (0.92 +/- 0.370, range 0.6-1.5 microM/l). Mean serum F- concentration did not correlate significantly with age and sex among control subjects, whereas such correlation was observed in patients with ESRD on dialysis. Mean serum F- concentration was significantly higher in patients on dialysis (2.67 +/- 1.09, range 0.8-5.2 microM/l) than normal controls. When grouped according to sex, the mean serum F- concentration in males (3.05 +/- 1.04, range 1.8-5.2 microM/l) was significantly higher than females (2.38 +/- 1.08, range 0.8-5.2 microM/l). When patients were grouped according to age, it was observed that F- concentration was significantly higher in patients with age groups 21-70 (2.86 +/- 1.05) than those with age group 13-20 years (1.42 +/- 0.531). Thus F- concentration correlated with age and sex, being higher in males and above 20 years. Despite appreciable clearance of F- (39-90%) across the peritoneum, patients on CAPD showed higher serum F- concentration than those on HD (3.1 +/- 1.97 vs 2.5 +/- 1.137 microM/l). Of the total 39 patients on dialysis 39% had their serum F- concentration above 3.0 microM/l, posing the risk of renal osteodystrophy.   相似文献   
7.
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   
8.
MALARIA RESULTS IN TWO SEEMINGLY PARADOXICAL PERTURBATIONS OF THE IMMUNE RESPONSE: polyclonal B-cell activation and immunosuppression. To determine what immunoregulatory role mediators secreted by adherent cells might play in these alterations, we cultured adherent cells from uninfected mice and from mice at different times during infection with Plasmodium berghei or P. yoelii. Culture supernatants obtained from these cells were tested for their ability to enhance the in vitro proliferative responses of thymocytes to suboptimal concentrations of concanavalin A or to inhibit the mitogen-stimulated proliferation of normal spleen cells. Supernatants obtained from adherent cells of mice early in infection (days 1 to 3) contained significantly elevated levels of enhancing activity which on Bio-Gel P-100 chromatography resembled lymphocyte-activating factor. Later in infection (days 4 and 5), these supernatants contained inhibitory activity. Normal adherent cells, when cocultivated in vitro with parasitized erythrocytes, ingested parasite debris and were stimulated to produce the enhancing factor. At high parasite/adherent-cell ratios, cells elaborated an inhibitory factor. These findings suggest that during malaria, adherent cells are converted from a nonspecific helper role to a nonspecific suppressor role. This modulation in function may be due to the direct interaction between adherent cells and parasitized erythrocytes.  相似文献   
9.
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   
10.
The possibility that soluble products of Schistosoma mansoni eggs might participate in the pathogenesis of hepatic fibrosis in schistosomiasis was investigated. Both crude saline extracts of eggs (soluble egg antigen [SEA]) and a partially purified SEA fraction contained activity which stimulated guinea pig and human dermal fibroblasts to proliferate in vitro, as measured by uptake of [3H]thymidine. Maximum activity was present in fractions which eluted from Sephacryl S-200 with an apparent molecular weight of less than or equal to 12,500 and in fractions which had an estimated pI 8, as determined by preparative isoelectric focusing of partially purified SEA. Activity in crude SEA was not removed by chromatography on concanavalin A-Sepharose 4B. When concanavalin A-binding glycoproteins lacking intrinsic fibroblast-stimulating activity were incubated with spleen cells from infected or uninfected mice, fibroblasts-stimulating activity was detected in the culture supernatants. Thus, SEA contains two functionally distinct molecular species. One of these directly stimulates fibroblasts, whereas the other induces the release of a fibroblast-stimulating activity from lymphocytes or macrophages or both. Since these fibroblast-stimulating factors might be elaborated in the livers of infected individuals, these observations suggest a potential role of soluble schistome products in the pathogenesis of hepatic fibrosis in schistosomiasis.  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