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   947篇
  免费   72篇
  国内免费   15篇
耳鼻咽喉   6篇
儿科学   34篇
妇产科学   14篇
基础医学   64篇
口腔科学   50篇
临床医学   83篇
内科学   208篇
皮肤病学   20篇
神经病学   22篇
特种医学   188篇
外科学   122篇
综合类   56篇
预防医学   26篇
眼科学   13篇
药学   42篇
  1篇
中国医学   10篇
肿瘤学   75篇
  2023年   14篇
  2022年   34篇
  2021年   38篇
  2020年   18篇
  2019年   36篇
  2018年   36篇
  2017年   27篇
  2016年   23篇
  2015年   23篇
  2014年   35篇
  2013年   31篇
  2012年   48篇
  2011年   54篇
  2010年   26篇
  2009年   24篇
  2008年   10篇
  2007年   26篇
  2006年   22篇
  2005年   23篇
  2004年   10篇
  2003年   15篇
  2002年   10篇
  2001年   10篇
  2000年   7篇
  1999年   11篇
  1998年   26篇
  1997年   26篇
  1996年   21篇
  1995年   26篇
  1994年   22篇
  1993年   35篇
  1992年   7篇
  1991年   7篇
  1990年   16篇
  1989年   23篇
  1988年   27篇
  1987年   38篇
  1986年   22篇
  1985年   23篇
  1984年   15篇
  1983年   12篇
  1982年   6篇
  1981年   12篇
  1980年   13篇
  1978年   7篇
  1977年   6篇
  1976年   4篇
  1975年   6篇
  1937年   4篇
  1929年   4篇
排序方式: 共有1034条查询结果,搜索用时 0 毫秒
61.
There have been extensive observations that RNA containing repetitive elements accumulates in transformed cells and tumor tissues. In the present study, we first obtained result consistent with previous observations by in situ hybridization.  相似文献   
62.
OBJECT: The goals of this study were to define the incidence of seizures in children with low-grade tumors, study seizure outcome after lesionectomy in these children, and identify risk factors for poor seizure outcome, METHODS: The authors performed a retrospective chart review of children who harbored low-grade brain tumors, experienced seizures, and were treated in a single institution, Statistical analyses included step-wise as well as single-variable binary logistic regression analyses.  相似文献   
63.
A previous study from this laboratory demonstrated that treatment of pregnant mice with 3-methylcholanthrene (MC) caused lung tumors in the offspring at 1 year after birth, the incidence of which correlated with fetal inducibility of Cyp1a1. Analysis by PCR amplification and allele- specific hybridization (ASO) of paraffin-embedded tumors generated from that study revealed the presence of point mutations in exon 1 of the Ki- ras gene. This work has now been expanded by PCR amplification and ASO analysis of 31 additional lesions. Point mutations were found in 37 of the 47 (79%) lesions analyzed in this and the previous study, the majority of which were G-->T transversions in the first or second base of codon 12. The mutational spectrum appeared to be dependent on the relative stage of differentiation of the lesion, as both the incidence of mutation and type of mutation produced correlated with malignant progression. Mutations occurred in 60% of the hyperplasias, 80% of the adenomas and 100% of the adenocarcinomas. In the lesions with mutations, GLY12-->CYS12 transversions occurred in 100% of the hyperplasias, 42% of the adenomas and 14% of the adenocarcinomas. The GLY12-->VAL12 transversions occurred in none of the hyperplasias, 42% of the adenomas and 57% of the adenocarcinomas. The remaining mutations, which consisted of ASP12 transitions and ARG13 transversions, occurred only in adenomas (17%) and adenocarcinomas (29%). Between this study and our previous analyses, the identity of the mutations obtained by ASO were confirmed by sequence analysis of eight of the 37 lesions that harbored mutations at the Ki-ras gene locus. There were no differences in the type or incidence of mutations relative to the metabolic phenotype or sex of the mice. These data suggest that mutational activation of the Ki-ras gene locus is an early event in transplacental lung tumorigenesis, and that the type of mutations produced by exposure to chemical carcinogens can influence the carcinogenic potential of the tumor. This may have prognostic significance in determining the malignant progression of the neoplasm.   相似文献   
64.
Nyberg  DA; Mack  LA; Laing  FC; Jeffrey  RB 《Radiology》1988,167(3):619-622
Endovaginal sonography results were compared with quantitatively determined human chorionic gonadotropin (hCG) levels in 84 women referred for early pregnancy complications. Of the 27 with normal intrauterine pregnancies, an intrauterine gestational sac was prospectively identified in one of five cases (20%) in which hCG levels were below 500 IU/L (Second International Standard), four of five (80%) with hCG levels of 500-1,000 IU/L, and all 17 with hCG levels above 1,000 IU/L. In comparison, 17 of the 26 women with ectopic pregnancies (65%) had hCG levels greater than 1,000 IU/L, and none of the 26 had an intrauterine gestational sac. Endovaginal sonography demonstrated an adnexal mass and/or a gestational sac-like structure in 16 of the 17 cases (94%) in which hCG levels were above 1,000 IU/L, compared with only three of the nine (33%) with lower hCG levels (P less than .01). These findings indicate that an intrauterine gestational sac should be normally visualized with endovaginal sonography when the hCG level exceeds 1,000 IU/L, and that visualization of an extrauterine gestational sac and/or adnexal mass is significantly more likely in ectopic pregnancies when the hCG level exceeds 1,000 IU/L.  相似文献   
65.

Background

In view of increase in incidence of exptrapulmonary tuberculosis after the epidemic of human immunodeficiency virus infection, the clinical profile of extrapulmonary tuberculosis in patients with HIV infection was studied.

Method

The study population comprised patients of HIV infection with extrapulmonary tuberculosis. Work up included history, clinical examination, sputum for acid fast bacilli, chext X-ray, ultrasonography (USG) abdomen, fine needle aspiration cytology(FNAC), transbronchial needle aspiration (TBNA) and computed tomography of chest.

Results

There were 50 cases, all males with mean age of 35 years. 24(48%) were without pulmonary tuberculosis and 26(52%) had pulmonary tuberculosis. 41(82%) had disseminated disease and 9(18%) involve one site. Fever and weight loss were the most frequent symptoms (79% and 58% respectively) in cases without pulmonary tuberculosis. The most frequent extrapulmonary site was lymph node in 46(92%), followed by spleen in 13(26%), pleura 9(18%), miliary 7(14%) and hepatic 1(2%). The diagnosis was confirmed by invasive methods in 30 out of 50(60%) cases [FNAC in 23(88%), TBNA in 2(25%) and pleural biopsy in 5(55%)].

Conclusion

In HIV infected patients, the most common extrapulmonary site is lymph mode followed by spleen.Key Words: Extrapulmonary TB, HIV Infection  相似文献   
66.
67.
Xenograft transplantation   总被引:1,自引:0,他引:1  
Interest in xenotransplantation has increased because conventional organ transplantation has been limited by a shortage of human organs. Although xenotransplantation could alleviate the existing and anticipated need for tissues and organs, the application is hindered by various biologic obstacles. This article reviews the basis for the demand for xenotransplantation, the obstacles to clinical application, and potential approaches to overcoming those obstacles.  相似文献   
68.
Congenital esophageal stenosis CES is an uncommon anomaly that rarely goes undiagnosed until adulthood. We report 2 cases of CES. The first was a one-month-old baby boy who was referred for work up of swallowing disorder and recurrent pneumonias. The diagnosis was confirmed by a continuous fluoroscopic esophagogram, and endoscopic exploration. Simple dilatation resolved his symptoms completely. The second was an 18-month-old boy, who was referred with a feeding gastrostomy due to complete esophageal obstruction. Resection and end-to-end anastomosis was performed with uneventful postoperative course.  相似文献   
69.

Study Objective

To analyze and investigate reports associated with uterine artery embolization used for treatment of myomas using this database.

Design

A retrospective review of the Manufacturer and User Facility Device Experience (MAUDE) database for events related to uterine artery embolization (Canadian Task Force Classification III).

Setting

The MAUDE database was accessed online.

Patients

Patients with myomas undergoing uterine artery embolization.

Interventions

The MAUDE database was accessed online and searched for events related to uterine artery embolization reported between 1998 and 2018. These reports were reviewed and analyzed, reported events were categorized, and other relevant information was collected and tabulated.

Measurements and Main Results

A total of 193 reports published during the study period were identified. Pain was the most frequently reported event (68 events; 35.2%), followed by vaginal discharge (45 events; 23.3%), operational misfire (37 events; 19.2%), and fever or infectious complications (36 events; 18.7%). A surgical procedure was required in 27 events (14.0%), with hysterectomy reported in 7.8% of the events. Death following this procedure was mentioned in 5 events (2.6%).

Conclusion

The MAUDE database may be useful for clinicians using a Food and Drug Administration–approved medical device to identify the occurrence of adverse events and complications. A variety of adverse events associated with the use of uterine artery embolization were reported to the MAUDE database related to its use in the treatment of uterine myomas. We encourage physicians to review the MAUDE database when using medical devices, because this is an important tool to assess uncommon but major problems that could be associated with a medical device.  相似文献   
70.
Interleukin-6 is one of the factors affecting sensitivity to cytotoxic agents. Therefore, the current study was designed to investigate the role of IL-6 and IL6 receptors in the cytotoxic effects of zerumbone in ovarian and cervical cancer cell lines (Caov-3 and HeLa, respectively). Exposure of both cancer cells to zerumbone or cisplatin demonstrated growth inhibition at a dose-dependent manner as determined by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,Sdiphenyltetrazolium bromide) reduction assay. Both laser scanning confocal microscopy and TUNEL assay showed typical apoptotic features in treated cells. The studies conducted seems to suggest that zerumbone induces cell death by stimulating apoptosis better than cisplatin, based on the significantly higher percentage of apoptotic cells in zerumbone's treated cancer cells as compared to cisplatin. In addition, zerumbone and cisplatin arrest cancer cells at G2/M phase as analyzed by flow cytometry. Our results indicated that zerumbone significantly decreased the levels of IL-6 secreted by both cancer cells. In contrast, HeLa and Caov-3 cells were still sensitive to cisplatin and zerumbone, even in the presence of exogenous IL-6. However, membrane-bound IL-6 receptor is still intact after zerumbone treatment as demonstrated using an immune-fluorescence technique. This study concludes that the compound, zerumbone inhibits both cancer cell growth through the induction of apoptosis, arrests cell cycle at G2/M phase and inhibits the secretion levels of IL-6 in both cancer cells. Therefore, zerumbone is a potential candidate as a useful chemotherapeutic agent in treating both cervical and ovarian cancers in future.  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