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   793篇
  免费   50篇
  国内免费   6篇
耳鼻咽喉   3篇
儿科学   24篇
妇产科学   21篇
基础医学   117篇
口腔科学   20篇
临床医学   62篇
内科学   228篇
皮肤病学   11篇
神经病学   46篇
特种医学   49篇
外科学   113篇
综合类   11篇
预防医学   78篇
眼科学   18篇
药学   20篇
中国医学   2篇
肿瘤学   26篇
  2023年   5篇
  2022年   12篇
  2021年   19篇
  2020年   14篇
  2019年   24篇
  2018年   18篇
  2017年   17篇
  2016年   10篇
  2015年   12篇
  2014年   38篇
  2013年   38篇
  2012年   38篇
  2011年   57篇
  2010年   30篇
  2009年   18篇
  2008年   41篇
  2007年   40篇
  2006年   45篇
  2005年   38篇
  2004年   38篇
  2003年   26篇
  2002年   36篇
  2001年   24篇
  2000年   18篇
  1999年   19篇
  1998年   6篇
  1997年   9篇
  1996年   4篇
  1995年   5篇
  1994年   6篇
  1993年   7篇
  1992年   14篇
  1991年   9篇
  1990年   10篇
  1989年   11篇
  1988年   7篇
  1987年   5篇
  1986年   10篇
  1985年   9篇
  1984年   3篇
  1982年   3篇
  1981年   4篇
  1979年   4篇
  1977年   5篇
  1975年   5篇
  1974年   4篇
  1973年   7篇
  1970年   6篇
  1968年   3篇
  1965年   3篇
排序方式: 共有849条查询结果,搜索用时 31 毫秒
1.
Solitary bronchioloalveolar carcinoma: CT criteria   总被引:14,自引:0,他引:14  
The computed tomographic (CT) scans of 30 patients with solitary bronchioloalveolar carcinoma were reviewed. Common features at CT included the peripheral or subpleural location of a pulmonary mass (25 cases), pseudocavitation (18 cases), heterogeneous attenuation (17 cases), irregular margins forming a star pattern (22 cases), and pleural tags (21 cases). Using these CT criteria, four independent observers attempted to identify cases of bronchioloalveolar carcinoma from a larger sample of lung cancers and benign lesions by categorizing a series of test cases into four probability categories. Although the bronchioloalveolar carcinomas were correctly ranked in the two highest probability categories 75% of the time (in 45 of 60 cases), there was considerable overlap with other lung lesions, particularly with adenocarcinoma and large cell undifferentiated carcinoma. However, even though the typical features of bronchioloalveolar carcinoma are not invariable or highly specific, they are characteristic enough to suggest the diagnosis.  相似文献   
2.
M Mercado  M E Molitch  G Baumann 《Diabetes》1992,41(5):605-609
Poorly controlled insulin-dependent diabetes mellitus (IDDM) is associated with elevated basal plasma growth hormone (GH), disproportionally low insulin-like growth factor I (IGF-I) levels, and impaired somatic growth. These derangements in the GH-IGF axis imply a state of GH resistance. The mechanism of GH resistance is unknown; it may involve a defect at the level of the GH receptor, unresponsiveness due to a postreceptor defect in GH action, or both. To investigate a potential receptor involvement, we measured plasma high-affinity GH-binding protein (GHBP), which represents a truncated GH receptor and may reflect GH receptor levels in tissues, in patients with IDDM, patients with non-insulin-dependent diabetes (NIDDM), and nondiabetic control subjects. Patients with IDDM had significantly lower plasma GHBP levels than either patients with NIDDM or nondiabetic control subjects (mean value 18.2 vs. 24.6 and 23.8% GH bound/ml plasma, respectively, P less than 0.001). This difference persisted when only lean patients (less than 115% ideal body wt) were included in the analysis. Basal plasma GH levels were significantly elevated in IDDM compared with either patients with NIDDM or nondiabetic control subjects (mean 6.9 vs. 2.1 and 2.0 micrograms/L, respectively, P less than 0.001), whereas IFG-I levels were not significantly different in IDDM and NIDDM. No correlations were found between levels of GHBP and HbA1, duration of diabetes, or plasma GH. GHBP and IGF-I levels were significantly correlated in NIDDM but not in IDDM. We conclude that IDDM is associated with low GHBP levels and that GH resistance found in this disorder may be mediated, at least in part, by a decrease in GH receptor levels.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
3.
4.
Adenoid cystic carcinoma of the breast diagnosed by fine-needle aspiration   总被引:2,自引:0,他引:2  
Fine-needle aspiration cytology remains a useful tool for preoperative diagnosis of breast lesions. We describe a case of adenoid cystic carcinoma (ACC) of the breast detected by ultrasound-guided fine-needle aspiration (FNA). Subsequent histopathology corroborated the diagnosis. ACC is a rare but distinctive neoplasm of the breast that can be accurately diagnosed by FNA. Its infrequent presentation, favorable prognosis, and relatively conservative management in the breast prompt us to reinforce its features.  相似文献   
5.
6.
The association between MSHR coding region variation and hair colour in humans has been examined by genotyping 25 red haired and 62 non-red Caucasians, all of whom were 12 years of age and members of a twin pair study. Twelve amino acid substitutions were seen at 11 different sites, nine of these being newly described MSHR variants. The previously reported Val92Met allele shows no association with hair colour, but the three alleles Arg151Cys, Arg160Trp and Asp294His were associated with red hair and one Val60Leu variant was most frequent in fair/blonde and light brown hair colours. Variant MSHR genotypes are associated with lighter skin types and red hair (P < 0.001). However, comparison of the MSHR genotypes in dizygotic twin pairs discordant for red hair colour indicates that the MSHR gene cannot be solely responsible for the red hair phenotype, since five of 13 pairs tested had both haplotypes identical by state (with three of the five having both identical by descent). Rather, it is likely that additional modifier genes exist, making variance in the MSHR gene necessary but not always sufficient, for red hair production.   相似文献   
7.
OBJECTIVE: Decreases in circulating growth hormone (GH) and its main biological messenger insulin-like growth factor-I (IGF-I) have been interpreted as part of the aging process. Because estrogens participate in modulating GH synthesis and secretion, hypoestrogenism in menopausal women may lead to GH deficiency. The aim of the present study was to determine the effect of hormone replacement therapy (HRT) on both GH and IGF-I levels as well as insulin concentrations in 50 menopausal women. DESIGN: Patients were assigned randomly into two treatment groups of 25 each; one group received three cycles of conjugated equine estrogen (CEE) 0.625 mg/day for 21 days, and the other, 1.25 mg/day during 21 days. Each also received chlormadinone acetate for 5 days. There was a control group consisting of regularly menstruating women. RESULTS: In the menopausal women, HRT increased significantly (p < 0.001) the low levels of GH and IGF-I; on the contrary the baseline insulin levels declined (p < 0.001) with HRT. A significant linear correlation (r = 0.90) was found between GH and IGF-I as well as with estradiol levels (r = 0.74) in the group of menopausal women receiving CEE 0.625 mg/day. This group of patients had a significant correlation (r = -0.63) between insulin and estradiol levels. No correlation was observed in the group receiving CEE 1.25 mg/day. CONCLUSIONS: HRT restored GH, IGF-I, and insulin levels to normal values in all women. Further research needs to be done to establish the beneficial effect of HRT regarding the prevention of the metabolic effects presumably caused by derangement in the somatotropic axis associated with aging.  相似文献   
8.
A molecular clone representing 445 base pairs at the 3' end of infectious bursal disease virus (IBDV) genome segment B was used in a dot blot hybridization assay to detect viral RNA from cell culture and from chicken bursa and spleen tissue specimens. The cloned nucleotide sequence represents approximately 14% of the virus-encoded polymerase (VP-1) gene. The lower detection limit of radiolabeled probes prepared from this clone was 0.1 ng of IBDV double-stranded RNA. The probe had broad specificity and was used to detect four serotype 1 IBDV strains and one serotype 2 IBDV strain. This probe, however, did not cross-react with nucleic acid extracted from nine unrelated poultry viruses. A rapid procedure for isolation of IBDV genomic RNA from bursa and spleen tissue specimens was developed and used with the dot blot hybridization assay to detect IBDV strains in tissue samples from experimentally infected and commercially reared chickens.  相似文献   
9.
Tripoloni  D. E.  Canaro García  M. I.  Cassani  F.  Zanni  M.  Sosa Mercado  A. 《Hernia》2021,25(5):1183-1187
Introduction

The EHS clinical guidelines recommend the use of mesh to repair symptomatic primary inguinal hernias (PIH) in adult males but, in spite of this, it begs the question as to why there is still place for tissue techniques. Lack of stratification of patients according to risk of recurrence in RCTs might be a cause of results disparity, since medial and mixed are hernias with higher risk of recurrence (HRRH), whereas lateral hernias present a lower risk (LRRH).

Objective

To determine whether the lack of stratification may lead to questionable conclusions regarding the protective effect of mesh techniques and to identify other methodological flaws.

Methods

In the RCTs included in the clinical guidelines that addressed recurrences of PIH after mesh and non-mesh techniques, we assessed the type of hernias classification used, the number needed to treat in LRRH and HRRH and the statistical power.

Results

Most of trials were underpowered; five studies classified the hernia types; in the three studies that compared the recurrence rates of LRRH and HRRH the effect of mesh techniques was small; only two trials record data needed to calculate the NNT in LRRH (46 y 84 patients, respectively).

Conclusion

The idea that mesh techniques reduce the recurrence rate in all PIHs is not supported by high level of evidence. The NNT for pure lateral hernias was very high and should be interpreted taking into account chronic pain rates and costs.

  相似文献   
10.
Giant cell reparative granuloma of the orbit   总被引:1,自引:0,他引:1  
PURPOSE: To report a case of giant cell reparative granuloma occurring in the orbit and to discuss its clinical, radiologic, and histopathologic characteristics in contrast with other similar lesions. METHODS: A 38-year-old man developed pain and mild proptosis of the left eye. Computed tomography and magnetic resonance imaging demonstrated an intraosseous cystic orbital mass. Excisional biopsy disclosed giant cell reparative granuloma of the orbit. RESULT: At 11 months' follow-up, the patient had normal vision, with no tumor recurrence. CONCLUSION: Giant cell reparative granuloma of the orbit is a rare benign fibro-osseous proliferation that is generally seen in young adulthood. It should be considered in the differential diagnosis of orbital fibro-osseous proliferation. Surgical excision and curettage is the therapeutic method of choice.  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