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   77589篇
  免费   4155篇
  国内免费   265篇
耳鼻咽喉   1115篇
儿科学   2469篇
妇产科学   1564篇
基础医学   10082篇
口腔科学   3496篇
临床医学   5120篇
内科学   18684篇
皮肤病学   2258篇
神经病学   6783篇
特种医学   2047篇
外国民族医学   1篇
外科学   10434篇
综合类   421篇
一般理论   22篇
预防医学   6372篇
眼科学   1820篇
药学   5089篇
中国医学   420篇
肿瘤学   3812篇
  2024年   67篇
  2023年   586篇
  2022年   1058篇
  2021年   2477篇
  2020年   1291篇
  2019年   2299篇
  2018年   3233篇
  2017年   1961篇
  2016年   1935篇
  2015年   2029篇
  2014年   2725篇
  2013年   3745篇
  2012年   5964篇
  2011年   6535篇
  2010年   3279篇
  2009年   2456篇
  2008年   4978篇
  2007年   4950篇
  2006年   4438篇
  2005年   4330篇
  2004年   4084篇
  2003年   3677篇
  2002年   3240篇
  2001年   1927篇
  2000年   2310篇
  1999年   1438篇
  1998年   443篇
  1997年   305篇
  1996年   280篇
  1995年   240篇
  1994年   223篇
  1993年   184篇
  1992年   334篇
  1991年   325篇
  1990年   278篇
  1989年   231篇
  1988年   244篇
  1987年   206篇
  1986年   165篇
  1985年   163篇
  1984年   151篇
  1983年   137篇
  1982年   78篇
  1981年   65篇
  1980年   71篇
  1979年   89篇
  1978年   80篇
  1975年   61篇
  1971年   63篇
  1967年   62篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.

Objectives

Gene expression analysis has identified several breast cancer subtypes, including luminal, epidermal growth factor receptor-2 positive (HER2+), and basal-like. To determine if our proposed molecular taxonomy correlates with biological and clinical behavior. This is based on four biological markers: estrogen and progesterone receptors (ER and PR, respectively), HER2 and the epidermal growth factor receptor-1 (HER1), all of them being determined by quantitative assays.

Study design

The biological parameters were examined by enzyme immunoassay, radioligand-binding assay or ELISA, in tumors from 787 patients with invasive breast cancer. Patients were prospectively evaluated over a median follow-up period of 50 months. Subtype definitions were as follows: luminal (ER+), HER2+ (HER2+, ER−, PgR−) and basal-like (HER2−, ER−, PgR−). In addition, we divided basal tumors into two groups based on their HER1 status.

Results

A 55.8% of tumors were of luminal type, 11.9% basal-like HER1+, 10.7 basal-like HER1−, and the remainder 21.6% HER2+. Both HER2+ and basal-like subtypes were more frequent in younger and premenopausal women, showing a higher percentage of cases of poorly differentiated tumors and higher S-phase fraction, when compared with those of luminal subtype. Multivariate analysis demonstrated that the subtype of tumor was related to both relapse and overall survival, being those of luminal subtype associated with the best prognosis.

Conclusions

Through the classification of breast tumors in four groups, according to their ER, PgR, HER2 and HER1 status, it is possible to obtain a major division of breast tumors associated with significant differences in biological features and clinical behavior.  相似文献   
993.

Objective

We aimed to study the cross-sectional area of levator ani muscle and the doppler velocimetric parameters of vessels its in premenopausal and postmenopausal women.

Study design

Sixty-four patients, divided into 3 groups, were assessed: group I (20 women—average age 28 years) premenopausal and nulliparous (control); group II (24 women—average age 38 years, vaginal delivery 1–4) premenopausal with vaginal deliveries; group III (20 women—average age 55 years, parity 0–4) postmenopausal without hormonal therapy. Doppler velocimetry of levator ani muscle vessels through resistance and pulsatility indices was used and the means of the groups compared by adjusting the weighed variance model with multiple comparisons, according to Tukey's method. Similarly, we measured the cross-sectional area of the muscle using ultrasonography.

Results

There was a significant increase in resistance and pulsatility indices in postmenopausal patients as compared to the other two groups. We also observed a significant decrease in the cross-sectional area of the muscle of postmenopausal patients when compared to those in premenopausal.

Conclusion

The obtained results allow us to conclude that levator ani muscle vascularization significantly decreases after menopause (age and/or hipoestrogenism) and that it can be assumed that vaginal delivery does not promote long-term alterations in levator ani muscle vascularization. We also observed a significant decrease in the cross-sectional area of the muscle in postmenopausal women when compared to those in premenopausal.  相似文献   
994.
995.
OBJECTIVES: The objectives were to assess the prevalence of high-risk HPV in the male sexual partners of women with HPV-induced lesions, and correlate it with biopsies guided by peniscopy. STUDY DESIGN: Fifty-four asymptomatic male sexual partners of women with low-grade squamous intra-epithelial lesions (LSIL) associated with high-risk HPV were examined between April 2003 and June 2005. The DNA-HPV was tested using a second-generation hybrid capture technique in scraped penile samples. Peniscopy identified acetowhite lesions leading to biopsy. RESULTS: High-risk HPV was present in 25.9% (14 out of 54) of the cases. Peniscopy led to 13 biopsies (24.07%), which resulted in two cases of condyloma, two cases of intra-epithelial neoplasia (PIN) I, one case of PIN II, and eight cases of normal tissue. The high-risk HPV test demonstrated 80% sensitivity, 100% specificity, 100% positive predictive value, and 88.9% negative predictive value for the identification of penile lesions. There was a greater chance of finding HPV lesions in the biopsy in the positive cases of high-risk HPV with abnormal peniscopy (p=0.007); OR=51 (CI 1.7-1527.1). CONCLUSION: Among asymptomatic male sexual partners of women with low-grade intra-epithelial squamous lesions, those infected by high-risk HPV have a higher chance of having abnormal penile tissue compared with male partners without that infection.  相似文献   
996.

Introduction

Microinvasive carcinoma represents a subgroup within cervical cancer that is characterized by having a good prognosis and the possibility of treatment through conservative approaches.

Material and methods

We studied data from 60 patients treated at our hospital from 1994 to 2001. The diagnosis was made by the loop electrosurgical excision procedure (LEEP).

Results

Of all treated patients, 83.3% had stage IA1 carcinomas and 16.6% were in stage IA2. All tumors were squamous carcinomas, except one, which was a mucinous adenocarcinoma. Forty patients with stage IA1 tumors underwent total hysterectomy, whilst the remainder were treated by LEEP or, in two patients, through a cervical stump excision. Except for one patient with contraindications for surgery, all IA2 patients underwent radical surgery consisting of radical hysterectomy with bilateral iliac lymphadenectomy. Relapse occurred in only one patient with a stage IA1 tumor, who then underwent colpectomy.

Conclusions

Our data support the current trend of increasing the use of conservative treatments and confirm the excellent prognosis of this neoplasm.  相似文献   
997.

Objective

The objective was to evaluate the prevalence of human papillomavirus (HPV) in the anal canal of women with cervical intraepithelial neoplasia (CIN) grade III.

Study design

Two groups were compared. In group I (study group), 40 women who had undergone cervical biopsy with a histopathological result indicating CIN III were evaluated. Group II (control) consisted of 40 women with normal results from colposcopic examination and colpocytological tests. The women in group I who presented high-grade neoplasia in colpocytological tests underwent collection of material from the uterine cervix and anal canal for investigating HPV DNA using the Hybrid Capture II® technique. Colposcopy and cervical biopsy were then performed. If CIN III was confirmed, HPV DNA was investigated in the material collected. In group II, colpocytological tests and colposcopy were performed and, if normal, the procedure was similar to that followed for group I, except that no biopsy was performed.

Results

In group I, 39 women (97.5%) were positive for HPV in the uterine cervix and 14 women (35%) in the anal canal. In group II, only four women (10%) had a positive HPV test, for both the uterine cervix and the anal canal.

Conclusions

The prevalence of HPV in the anal canal of the women with CIN III was greater than in the women without CIN III.  相似文献   
998.
We evaluated if the inhibitory effect of 17alpha-hydroxyprogesterone caproate (17P) on cervical ripening is mediated by cervical proinflammatory agents. Women with singleton pregnancy and intact membranes, between 25 and 33 weeks + 6 days, were randomly allocated either to observation (22 cases, controls) or to receive 341 mg of intramuscular 17P (23 cases, 17P group), twice a week, until 36 weeks. Just before randomization, 7 and 21 days later, a cervical swab for interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor alpha (TNF-alpha), and nitrates/nitrites (NOx) assays was collected. Moreover, an ultrasound measure of cervical length (CL) was performed at the same time. At randomization, both groups of women showed similar levels of cervical ILs and NOx. In the 17P group, cervical IL-1beta levels were significantly decreased at day 21 ( P = 0.036); in controls, they remained stable throughout the observation period. There was no significant change in IL-6, IL-8, TNF-alpha, and NOx in either group. Women in the control group had a progressive CL shortening until day 21 (median shortening of 4 mm), and this shortening was significantly less in the 17P group (median shortening of 2 mm; P = 0.017). In patients at risk of preterm labor, high-dose 17P simultaneously inhibits both cervical proinflammatory IL-1beta secretion and the progressive shortening of the cervix.  相似文献   
999.
The term placenta accreta is used to describe any placental implantation in which there is abnormally firm adherence to the uterine wall. This condition complicates 1/2,500 deliveries and is rising in incidence. Abnormal placentation is associated with increased maternal morbidity and mortality from severe hemorrhage, uterine perforation, infection and loss of fertility. The reported experience of methotrexate treatment in the conservative management of placenta accreta is scant. Three cases of partial placenta increta managed with methotrexate are described. The patients were assessed with clinical surveillance, serum beta human chorionic gonadotrophin (beta-hCG) and imaging (ultrasonography and magnetic resonance in one case). In all cases conservative management with methotrexate resulted in undetectable serum beta-hCG, a decrease in the size of partial placenta retained, and undetectable vascularization.  相似文献   
1000.
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