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   267035篇
  免费   5498篇
  国内免费   332篇
耳鼻咽喉   2269篇
儿科学   9266篇
妇产科学   5212篇
基础医学   29189篇
口腔科学   3383篇
临床医学   19625篇
内科学   53308篇
皮肤病学   2700篇
神经病学   24611篇
特种医学   11858篇
外国民族医学   32篇
外科学   40166篇
综合类   2716篇
一般理论   23篇
预防医学   26101篇
眼科学   4300篇
药学   15624篇
中国医学   877篇
肿瘤学   21605篇
  2023年   568篇
  2022年   1031篇
  2021年   2350篇
  2020年   1223篇
  2019年   2085篇
  2018年   25818篇
  2017年   19717篇
  2016年   21234篇
  2015年   3041篇
  2014年   3573篇
  2013年   4750篇
  2012年   12957篇
  2011年   26865篇
  2010年   21899篇
  2009年   14249篇
  2008年   24492篇
  2007年   26789篇
  2006年   5612篇
  2005年   7297篇
  2004年   8209篇
  2003年   8861篇
  2002年   6788篇
  2001年   2599篇
  2000年   2857篇
  1999年   2170篇
  1998年   870篇
  1997年   660篇
  1996年   539篇
  1995年   492篇
  1994年   432篇
  1993年   369篇
  1992年   1097篇
  1991年   989篇
  1990年   1019篇
  1989年   891篇
  1988年   770篇
  1987年   786篇
  1986年   669篇
  1985年   621篇
  1984年   450篇
  1983年   369篇
  1982年   240篇
  1979年   317篇
  1978年   239篇
  1974年   267篇
  1973年   248篇
  1972年   242篇
  1971年   237篇
  1969年   234篇
  1968年   239篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
BACKGROUND: If cervical polyps are a common pathology in the female adult population, giant cervical polyps with a size greater than 4 cm are rare and until now only several cases have been described in literature. The size and the clinical presentation can mimic a cervical neoplasia. The management is surgical and can be conservative regarding to the benign pathological feature of this entity. CASE REPORT: We report the case of a giant cervical polyp of 5.5 cm occurring in a multiparous 47-year-old woman who clinically presented vaginal bleeding. The lesion was resected by electrosurgery with no recurrence 7 months after surgery. CONCLUSION: The diagnosis, management and outcome of this rare entity had been reviewed according to the literature.  相似文献   
992.
BACKGROUND: Duplicated collecting systems comprises renal units containing two pyelocalyceal systems associated with a single ureter or double ureters and is the most common upper tract anomaly. CASE: This report presents a rare entity: an adult woman who had giant hydroureter of upper-pole moiety of the duplex kidney, which was an incidental finding during cesarean section. Heminephroureterectomy was done containing 2 L of fluid. This case is the first of its kind during cesarean section. CONCLUSION: The cause of this unusually massive degree of dilatation of the upper-pole moiety of the duplicated collecting system is uncertain, but may have resulted from an error in the development or because of VUR. We suggest mandatory intraabdominal examination after delivering uterus while conducting a cesarean section.  相似文献   
993.
BACKGROUND: Peutz-Jeghers Syndrome (PJS) is a rare autosomal dominant disorder characterized by gastrointestinal hamartomatous polyps and mucocutaneous pigmentation. Patients with PJS have increased risk for gastrointestinal, breast, and female genital tract cancers. CASE: Multiple genital tract cancers in a 34-year-old woman with PJS are described. The patient, who was admitted to our department with severe vaginal bleeding, was performed right salpingo-oophorectomy because of pure gonadoblastoma in 1996. In 2003, concomitant to cervical carcinoma, breast cancer was diagnosed. Patient underwent left modified radical mastectomy due to the invasive papillary carcinoma. The patient received six cycles combination chemotherapy and radiation therapy because of stage IIIB cervical cancer. CONCLUSION(S): This is the first case report presenting PJS associated with multiple genital tract tumors including ovarian gonadoblastoma in literature. The clinical significance of these tumors in PJS patients has been reviewed.  相似文献   
994.
INTRODUCTION: Tuberous sclerosis is an autosomal dominant disorder of hamartoma formation that can manifest as cardiac or central nervous system lesions and adversely affect maternal and fetal outcome. CASE REPORT: We report a case of maternal tuberous sclerosis with fetal cardiac rhabdomyoma detected in utero at 26 weeks gestation. CONCLUSION: To conclude, a pregnancy complicated by maternal or fetal tuberous sclerosis deserves careful vigilance and the fetus should undergo prenatal fetal Doppler echocardiography and if possible an MRI, so that parents can be counseled regarding its future prognostic implications.  相似文献   
995.
Filariasis is a helminthic infection caused by tissue nematodes. It is estimated that at least 120 million people are infected worldwide and another 1 billion are “at risk” of infection. The prevalence is increasing due to uncontrolled urbanization in many of the endemic countries. The geographical distribution is determined mainly by climate and the distribution of the mosquito vector. We report a case of huge filarial elephantiasis of the vulva, in a 40-year-old multipara with background history of secondary infertility. She had excision of the elephantoid vulva lesion under general anaesthesia. A nontender irreducible pedunculated mass (25 cm × 21 cm) with a large stalk arising from the right groin down to the ipsilateral labia majora was removed. A similar mass on the left groin, measuring 10 cm × 6 cm was removed. Diagnosis was confirmed at histopathologic analysis of the excised masses. Patient was placed on diethyl carbamazine.  相似文献   
996.

Objective

We sought to determine whether meconium-stained amniotic fluid is based on chronic hypoxia or not? In case of chronic hypoxia, higher red blood cell (Rbc) count and/or total hemoglobin levels (Hgb) and/or higher fetal hemoglobin (HbF) and/or lower adult hemoglobin (HbA) levels were expected when compared with controls.

Design

Case–control study.

Setting

Obstetric unit of a tertiary ministry of health hospital.

Sample

Fifty singleton pregnancies with meconium-stained amniotic fluid and 50 singleton pregnancies with clear amniotic fluid at all stages of labor.

Methods

Umbilical cord blood samples were collected for determination of total blood parameters and hemoglobin electrophoresis.

Main outcome measures

Red blood cell count, total hemoglobin, fetal and adult hemoglobin contents (HbF and HbA).

Results

Red blood cell count, total hemoglobin, fetal hemoglobin (HbF) and adult hemoglobin (HbA) contents were not different between meconium stained and clear amniotic fluid groups.

Conclusion

These results suggest that meconium passage may not be associated with chronic fetal hypoxia as demonstrated by similar red blood cell count, total hemoglobin values and fetal hemoglobin (HbF) and adult hemoglobin (HbA) contents.
  相似文献   
997.
Pregnancy and tuberculosis (TB)  To assess TB cases during pregnancy in a developing region retrospectively and to present two case reports. Objectives  Since TB cases activated by HIV infection during pregnancy are well reported in the literature, we aimed to investigate the aggressiveness of pulmonary TB among pregnant women and to assess the effects of TB on the fetus in Kutahya, an area where HIV positive cases are not seen. Materials and methods  The medical records between 2000 and 2005 of the Provincial Health Directorate and Dispensary Against Tuberculosis in Kutahya were reviewed and analyzed retrospectively. Results  Between 2000 and 2005, 667 pulmonary TB cases were examined in the Kutahya region. Of these, 106 occurred in women at reproductive ages between 20 and 44. All were HIV negative cases. In this area, five TB cases were found during pregnancy. There were three cases seen in the first trimester, but pregnancy was ended by curettage. Two women had pulmonary TB and gave birth. Five cases were evaluated as class 1 TB. During and after pregnancy, isoniazid, rifampin, ethambutol, and pyrazinamide (INH + RFP + ETB + PRZ) were used for the treatment. Resistance to anti-TB drugs was not seen during the treatment. Neither congenial nor neonatal TB was seen. Conclusion  Generally, TB is expected to be more aggressive during pregnancy. Since our cases were HIV negative, it can be thought that TB did not progress aggressively. Less aggressiveness and non-resistance to TB treatment in HIV-negative pregnant women compared with HIV-positive women were observed. Therefore, HIV infection results in greater mortality than the triple combination of human immunodeficiency virus, mycobacterium TB, and pregnancy. Besides, the advance of TB in pregnant women was not different from that in non-pregnant women in Kutahya. The fetus and the newborn were not affected. INH, RFP, ETB, and PRZ were used for therapy.  相似文献   
998.
Objective  Correct prenatal determination of the fetal right/left axis is essential for the diagnosis of fetal malformations, in particular congenital heart anomalies. A reliable method of transabdominal echocardiographic assessment of the fetal situs in the late second trimester was established. We aimed to determine the validity of the transvaginal approach to assess fetal axis. Method  The study group consisted of 108 consecutive women in the second trimester of a singleton pregnancy, undergoing elective transvaginal anatomy scans. All had undergone previous transabdominal echocardiography to establish fetal axis. The same technique was used to assess the fetal axis during the transvaginal study, and the findings were compared. Results  There was total agreement in fetal axis determination between transabdominal and transvaginal scans in all cases. The accuracy of the transvaginal study was not affected by maternal obesity, fetal position or the presence of cardiac malformation (in one case). Conclusion  Transvaginal ultrasonography is the reliable and accurate means of determining the fetal axis. Both affiliations are affiliated with Sackler Faculty of Medicine, Tel Aviv University.  相似文献   
999.
1000.
Cervical cancer continues to be the most common cause of death among women in developing countries. Methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MS) are critical enzymes of folate metabolic pathways. In this work, we have conducted a case–control study to assess the role of these two polymorphisms in cervical cancer development. We obtained blood samples from 200 women with cervical cancer and from equal matched controls and analysed using PCR-RFLP method. We found that the methylenetetrahydrofolate reductase variant CT and CT + TT genotypes decreased cervix cancer risk, statistically significant (OR:0.30, 95% CI: 0.18–0.51, P < 0.001 for CT and OR:0.29, 95% CI: 0.18–0.49, P = 0.0000006 for CT + TT). Similarly in those patients who used oral contraceptive with variant CT genotype, there was statistically highly significant reduced risk of cervix cancer (OR:0.25, 95% CI: –0.12–0.49, P < 0.001) of methylenetetrahydrofolate reductase gene. For the methionine synthase, 2756 variant AG and AG + GG genotypes were similarly associated with highly significant reduced risk of cervix cancer (OR: 0.13, 95% CI: 0.07–0.26, P < 0.001 for AG, and OR: 0.15, 95% CI: 0.08–0.27, P < 0.001 for AG + GG) genotypes. In conclusion, our study suggested that methylenetetrahydrofolate reductase and methionine synthase polymorphisms might have protective effect on the risk of cervical cancer in the North Indian women.  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