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   2476篇
  免费   107篇
  国内免费   11篇
耳鼻咽喉   73篇
儿科学   57篇
妇产科学   26篇
基础医学   374篇
口腔科学   46篇
临床医学   156篇
内科学   587篇
皮肤病学   7篇
神经病学   296篇
特种医学   148篇
外科学   317篇
综合类   5篇
一般理论   1篇
预防医学   114篇
眼科学   5篇
药学   172篇
中国医学   5篇
肿瘤学   205篇
  2023年   8篇
  2022年   20篇
  2021年   28篇
  2020年   17篇
  2019年   28篇
  2018年   27篇
  2017年   29篇
  2016年   46篇
  2015年   46篇
  2014年   47篇
  2013年   80篇
  2012年   135篇
  2011年   147篇
  2010年   89篇
  2009年   84篇
  2008年   139篇
  2007年   150篇
  2006年   150篇
  2005年   165篇
  2004年   157篇
  2003年   176篇
  2002年   186篇
  2001年   39篇
  2000年   17篇
  1999年   34篇
  1998年   54篇
  1997年   51篇
  1996年   43篇
  1995年   27篇
  1994年   32篇
  1993年   33篇
  1992年   30篇
  1991年   23篇
  1990年   24篇
  1989年   17篇
  1988年   18篇
  1987年   6篇
  1986年   7篇
  1985年   11篇
  1984年   19篇
  1983年   15篇
  1982年   14篇
  1981年   18篇
  1980年   18篇
  1979年   8篇
  1978年   15篇
  1977年   13篇
  1974年   5篇
  1970年   5篇
  1957年   6篇
排序方式: 共有2594条查询结果,搜索用时 15 毫秒
141.
Purpose The effect of coculturing mouse embryos with cryopreserved human oviduct epithelial cells was investigated. The cryopreserved cells in Cellbanker were thawed and cultured in Richard D. Goldsby culture medium to establish monolayers. Two-cell-stage mouse embryos were cultured alone (control group) or cocultured with monolayers established from cryopreserved cells (cryopreserved coculture group) or from fresh cells (fresh coculture group). The rates of embryo development and the qualities of the blastocysts in the three groups were compared.Results The two coculture groups had significantly higher blastocyst development rates (cryopreserved coculture group, 81.6%; fresh coculture group, 82.2%) than the control group (63.1%). The two coculture groups had significantly more blastomeres (cryopreserved coculture group, 108.3 ± 25.9; fresh coculture group, 108.4 ± 25.1) than the control group (87.7 ± 31.9).Conclusion The method of cryopreservation of human oviduct epithelial cells using Cellbanker is simpler than conventional cryopreservation methods. These cryopreserved human oviduct epithelial cells may provide a constant supply of cells for coculture for in vitro fertilization and embryo transfer.  相似文献   
142.

Research question

Is there any difference in ovarian steroid receptor expression and pattern of fibrosis in focal and diffuse adenomyosis and response to hormonal treatment?

Design

Prospective controlled study where biopsy samples were prospectively collected after surgery from 30 women with focal adenomyosis, 21 women with diffuse adenomyosis and 20 women with uterine myoma. Some of these women underwent 3–6 months of treatment with gonadotrophin-releasing hormone agonist (GnRHa) before surgery. Tissue expression of oestrogen receptor (ER) and progesterone receptor (PR) was analysed by immunohistochemistry. Distribution of tissue fibrosis was examined by Masson's trichrome staining with computer-based image analysis of fibrosis in tissues derived from women with and without adenomyosis.

Results

There was no difference in ER/PR expression in gland cells/stromal cells of adenomyotic lesions on the ipsilateral side of focal adenomyosis and the anterior/posterior walls of diffuse adenomyosis. Compared to myoma tissues, a relatively decreased expression of ovarian steroid receptors was observed in both focal and diffuse adenomyosis. Image analysis of tissue fibrosis indicated more fibrosis in both focal and diffuse adenomyosis compared to fibrosis in the myometrium derived from women with uterine myoma. The pattern of fibrosis was no different in tissues derived from GnRHa-treated and -untreated women with focal and diffuse adenomyosis.

Conclusions

No difference was found in the expression of ER/PR and entity of fibrosis between women with focal and diffuse adenomyosis regardless of GnRHa treatment. A lower expression of ER/PR compared to myoma tissue potentially clarifies the biological rationale of non-response to hormonal therapies for adenomyosis.  相似文献   
143.
Background:
Various risk factors have been investigated concerning the etiology of prostate carcinoma, but many questions about the significance of the risk factors remain unanswered. To evaluate the relationship between smoking and obesity in prostate cancer, a case-control study was performed.
Methods:
Between 1986 and 1995, 329 patients with untreated prostate cancer and 188 patients with benign prostate hyperplasia (control patients) were evaluated according to their smoking habits and the degree of obesity. Also, the progression of prostate cancer in relationship to smoking and obesity was examined.
Results:
Smoking and obesity were not risk factors for the development of prostate cancer (odds ratio, 0.986, 0.836; 95% confidence interval, 0.69-1.41, 0.57-1.24, respectively). Nor were smoking or obesity a risk factor for survival in stage D2 patients, however, in stage B1-D1 patients, obese men had a tendency for disease progression.
Conclusion:
This study demonstrated that neither smoking nor obesity increase the risk of developing prostate cancer, or the risk of disease progression in prostate cancer patients. However, obese men have a tendency for progression of stage B1-D1 prostate cancer although further studies are necessary to confirm this finding.  相似文献   
144.
Abstract: We report here an autopsy case of Binswanger's disease (BD) without hypertension and associated with cerebral infarction in the terminal stage. The female patient, who was 74 years old at the time of death, had initially demonstrated manic-depressive disorder-like mental disorder, followed by dementia and neurological deficits. A brain CT scan showed white matter low attenuation bilaterally and symmetrically. BD was clinically diagnosed despite the lack of hypertension. In the terminal stage, she suffered an infarction in the left anterior cerebral artery region, and died of pneumonia. Neuropathologically, we found the infarction of the left anterior cerebral artery region, demyelination, fibrillary gliosis, lacunae and arteriosclerosis of the small arteries and arterioles in the white matter.  相似文献   
145.
Mature cross-bred dogs were acutely exposed to 1,1,1-trichloroethane, trichloroethylene, and toluene. The changes in hematologic parameters, during and after exposure, are reported. A marked but temporary decrease in leukocytes was noted 30 min after the initation of exposure; no changes were observed in erythrocyte counts, hematocrit values, or thrombocytes counts with all three solvents. The decrease in the amount of neutrophils was particularly prominent. Based upon leukocyte differential counts, all types of leukocytes snowed a decrease. The decrease in leukocyte counts was the largest with exposure to trichloroethylene, followed by 1,1,1-trichloroethane, and toluene, respectively. A dose-response relationship was noted between exposure concentrations and decreased leukocyte counts,i.e., 1,1,1-trichloroethane and toluene from 200 to 700 ppm; trichloroethylene from 0 to 700 ppm.  相似文献   
146.
147.
In order to study differences in the effect of the neuroleptics due to time of administration, rats were administered chlorpromazine (CPZ) in a variety of combinations of dose and time and the sedation period was measured. There was daily fluctuation in the sedative effect and the pattern of fluctuation differed according to dosage. A similar study under the condition of reversed light and dark gave a reversed curve of the daily fluctuation, showing that the rhythm of light and dark controls the fluctuation externally. In an attempt to elucidate the mechanism of these phenomena, CPZ was administered at two different times, between which there was a significant difference in the sedation period, and time-course changes in plasma and brain concentration of the drug and its metabolites were measured. No difference was found. These results are interpreted as indicating that the phenomena could arise at the level of amine-receptor activity in the brain. In addition, daily fluctuation due to time of administration was noted in lethality.  相似文献   
148.
Aniline p-hydroxylation activity of rat liver microsomes was found to be enhanced, rather than inhibited, at aniline concentrations higher than about 3 mM. The cyanide-induced enhancement increased as the oxygen tension was increased. The activation by cyanide was, however, significantly diminished with liver microsomes from phenobarbital- and 3-methylcholanthrene-pretreated rats. The enhancement was also decreased when liver microsomes were fortified with NADPH-cytochrome P-450 reductase. Aniline hydroxylation by reconstituted systems consisting of partially purified preparations of several species of cytochrome P-450 and the reductase was inhibited by cyanide, though the degree of inhibition was dependent on the species of cytochrome P-450 used for reconstitution. In several respects, the cyanide-induced enhancement of aniline hydroxylation is different from the enhancement caused by acetone and 2,2'-bipyridine, but is similar to the activation by ethylisocyanide.  相似文献   
149.
PURPOSE: We investigated the risk factors having an impact on the achievement of stone-free status and on the success rate, as well as on the likelihood of recurrence, in patients undergoing shockwave lithotripsy. PATIENTS AND METHODS: We evaluated the characteristics and outcomes of 3023 patients (3254 renal units) with upper urinary-tract stones who underwent SWL at the Funabashi Clinic over a 13-year period. We assessed the stone-free and success rates for 2844 patients (3061 renal units) 3 months post-SWL. We also determined the recurrence rate for the 1078 patients (1139 renal units) who had achieved stone-free status at that time. RESULTS: Overall, stone-free status was achieved in 65.1% of patients, and the success rate was 85.7%. There were significant differences in the stone-free rates depending on patient age, history of urolithiasis, and presence of pyuria before SWL, as well as the number, location, size, and composition of the stones. Stones recurred in 326 of 1139 renal units (28.6%) during a mean follow-up of 36 months. The recurrence rates were 7.5%, 24.1%, and 33.0% after 1, 3, 5 years, respectively. Multiple stones, a history of urolithiasis, and stones located in the kidney or both kidneys plus the ureter significantly influenced recurrence. Multivariate analysis demonstrated that multiple stones were most significantly related to recurrence. CONCLUSION: Treatment with SWL has a low morbidity and high effectiveness. The number and location of stones and a history of urolithiasis significantly influence recurrence. Further studies of prophylactic therapy are required, especially for patients with these factors.  相似文献   
150.
OBJECTIVE: It is important for people to maintain an appropriate lifestyle through out life to enjoy a healthy life. We have already developed a health check questionnaire, "8020 Oral Healthiness Score", in an endeavor to help people aged 80 keep more than 20 teeth. The health check consists of ten questions chosen from our previous residents' study. Named the "Sawayaka Score" it has been in use since 1999. In the present study, we focused on the results of a three-year follow-up to determine whether the Score may predict tooth loss for screening purposes. METHODS: A total of 716 village residents who participated in medical and dental checkups in 1999 as the baseline year were followed in T village of Aichi-Prefecture. The total numbers of teeth lost were examined after 1-, 2- and 3-years and odds ratios with 95% confidence intervals (CI) were generated for analysis of screening. RESULTS: At the 1999 baseline, the average number of retained teeth was 23.7 +/- 6.2 (mean +/- standard error) (23.0 +/- 6.8 in males, and 24.4 +/- 5.5 in females), and the average oral health score (mean +/- standard error) was 13.1 +/- 3.9 points (12.8 +/- 4.0 in males, 13.4 +/- 3.9 in females). A low score of 4-8 at the baseline predicted major tooth loss, while an average score was associated with loss of only one or 2 teeth loss in the residents. The present study confirms that persons with a favorable lifestyle tend to retain more teeth. CONCLUSION: It can be concluded that the 8020 Oral Healthiness Score is a useful tool to support residents' oral health promotion and predict tooth loss.  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