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   6449篇
  免费   413篇
  国内免费   60篇
耳鼻咽喉   33篇
儿科学   178篇
妇产科学   121篇
基础医学   929篇
口腔科学   250篇
临床医学   532篇
内科学   1651篇
皮肤病学   134篇
神经病学   585篇
特种医学   150篇
外科学   672篇
综合类   8篇
一般理论   1篇
预防医学   303篇
眼科学   28篇
药学   420篇
中国医学   6篇
肿瘤学   921篇
  2024年   8篇
  2023年   53篇
  2022年   117篇
  2021年   199篇
  2020年   119篇
  2019年   146篇
  2018年   179篇
  2017年   118篇
  2016年   150篇
  2015年   182篇
  2014年   272篇
  2013年   333篇
  2012年   532篇
  2011年   481篇
  2010年   289篇
  2009年   252篇
  2008年   445篇
  2007年   429篇
  2006年   425篇
  2005年   425篇
  2004年   350篇
  2003年   339篇
  2002年   348篇
  2001年   60篇
  2000年   31篇
  1999年   47篇
  1998年   58篇
  1997年   57篇
  1996年   37篇
  1995年   43篇
  1994年   37篇
  1993年   19篇
  1992年   36篇
  1991年   30篇
  1990年   32篇
  1989年   21篇
  1988年   26篇
  1987年   15篇
  1986年   35篇
  1985年   13篇
  1984年   10篇
  1983年   12篇
  1982年   14篇
  1981年   13篇
  1980年   10篇
  1979年   8篇
  1971年   6篇
  1970年   7篇
  1969年   9篇
  1968年   8篇
排序方式: 共有6922条查询结果,搜索用时 31 毫秒
71.
72.
73.
Pre-implantation genetic diagnosis for aneuploidy testing (PGD-A) is a tool to identify euploid embryos during IVF. The suggested populations of patients that can benefit from it are infertile women of advanced maternal age, with a history of recurrent miscarriages and/or IVF failures. However, a general consensus has not yet been reached.After the clinical failure of its first version based on cleavage stage biopsy and 9 chromosome-FISH analysis, PGD-A is currently performed by 24 chromosome screening techniques on trophectoderm (TE) biopsies. This approach has been clearly demonstrated to involve a higher clinical efficiency with respect to the standard care, in terms of sustained pregnancy rate per transfer and lower miscarriage rate. However, data about PGD-A efficacy calculated on a per intention-to-treat basis, as well as an analysis of its cost-effectiveness, are still missing.TE biopsy is a safe and extensively validated approach with low biological and technical margin of error. Firstly, the prevalence of mosaic diploid/aneuploid blastocysts is estimated to be between 0 and 16 %, thus largely tolerable. Secondly, all the comprehensive chromosome screening (CCS) technologies adapted to, or designed to conduct PGD-A are highly concordant, and qPCR in particular has been proven to show the lowest false positive error rate (0.5 %) and a clinically recognizable error rate per blastocyst of just 0.21 %.In conclusion, there is a sufficient body of evidence to support the clinical application of CCS-based PGD-A on TE biopsies. The main limiting factor is the need for a high-standard laboratory to conduct blastocyst culture, biopsy and vitrification without impacting embryo viability.  相似文献   
74.
75.
Dedifferentiated endometrial cancer (DEC) is microscopically characterized by the presence of high-grade areas emerging from low-grade tumour. DEC is an aggressive tumour even when the dedifferentiated component represents only 20% of the entire neoplasm. A proper histological diagnosis is essential to define the most appropriate therapeutic approach for these tumors, since they are characterized by a particularly aggressive trend and by an extremely poor prognosis. We report a single case of DEC associated with dedifferentiated and adrenal metastasis, for which the patient underwent both abdominal-pelvic and cerebellar surgery. Dedifferentiated carcinoma of the endometrium is a poorly recognized neoplasm since they have not been clearly defined the histological features discriminating this neoplasm from high-grade endometrioid adenocarcinoma. Revising existing literature we found 79 described cases of central nervous system secondary involvement and 13 cases where the onset of the disease was characterized by neurological signs and symptoms. We could only find two reported cases of adrenal metastases originating from endometrial neoplasia but in no case of dedifferentiated endometrial carcinoma previously described has been reported the concomitant adrenal-cerebellar involvement.  相似文献   
76.
AIM: To compare the site, age and gender of cases of colorectal cancer (CRC) and polyps in a single referral center in Rome, Italy, during two periods.METHODS: CRC data were collected from surgery/pathology registers, and polyp data from colonoscopy reports. Patients who met the criteria for familial adenomatous polyposis, hereditary non-polyposis colorectal cancer syndrome or inflammatory bowel disease were excluded from the study. Overlap of patients between the two groups (cancers and polyps) was carefully avoided. The χ2 statistical test and a regression analysis were performed.RESULTS: Data from a total of 768 patients (352 and 416 patients, respectively, in periods A and B) who underwent surgery for cancer were collected. During the same time periods, a total of 1693 polyps were analyzed from 978 patients with complete colonoscopies (428 polyps from 273 patients during period A and 1265 polyps from 705 patients during period B). A proximal shift in cancer occurred during the latter years for both sexes, but particularly in males. Proximal cancer increased > 3-fold in period B compared to period A in males [odds ratio (OR) 3.31, 95%CI: 2.00-5.47; P < 0.0001). A similar proximal shift was observed for polyps, particularly in males (OR 1.87, 95%CI: 1.23-2.87; P < 0.0038), but also in females (OR 1.62, 95%CI: 0.96-2.73; P < 0.07).CONCLUSION: The prevalence of proximal proliferative colonic lesions seems to have increased over the last decade, particularly in males.  相似文献   
77.

Background/Objectives

A few studies have documented the effect of local anesthesia for minor dermatologic surgical procedures on children and their parents. Our objective was to evaluate the psychological effect and global satisfaction of a patient‐centered approach to dermatologic surgery under local anesthesia.

Methods

Two self‐administered questionnaires were used to evaluate the distress and global satisfaction of 388 children who underwent dermatologic surgery under local anesthesia, accompanied by oral and written therapeutic education measures (structured information and a cartoon brochure illustrating the procedure) addressed to children and parents. Distraction techniques were also used during the procedures.

Results

Although 54.5% of patients manifested some degree of fear, all other parameters analyzed (pain, surgery‐related distress, surgical team–patient and –family relationship, global satisfaction) indicated that the procedures resulted in limited distress and that the large majority of children and parents tolerated them well.

Conclusion

Specific measures for therapeutic pediatric patient education may be helpful in limiting discomfort, anxiety, and pain perception linked to procedures performed under local anesthesia. Further controlled studies are required to more precisely assess the benefits of specific therapeutic education measures.  相似文献   
78.
Although static magnetic fields (SMFs) are used extensively in the occupational and medical fields, few comprehensive studies have investigated their possible genotoxic effect and the findings are controversial. With the advent of magnetic resonance imaging-guided radiation therapy, the potential effects of SMFs on ionizing radiation (IR) have become increasingly important. In this study we focused on the genotoxic effect of 80 mT SMFs, both alone and in combination with (i.e. preceding or following) X-ray (XR) irradiation, on primary glioblastoma cells in culture. The cells were exposed to: (i) SMFs alone; (ii) XRs alone; (iii) XR, with SMFs applied during recovery; (iv) SMFs both before and after XR irradiation. XR-induced DNA damage was analyzed by Single Cell Gel Electrophoresis assay (comet assay) using statistical tools designed to assess the tail DNA (TD) and tail length (TL) as indicators of DNA fragmentation. Mitochondrial membrane potential, known to be affected by IR, was assessed using the JC-1 mitochondrial probe. Our results showed that exposure of cells to 5 Gy of XR irradiation alone led to extensive DNA damage, which was significantly reduced by post-irradiation exposure to SMFs. The XR-induced loss of mitochondrial membrane potential was to a large extent averted by exposure to SMFs. These data suggest that SMFs modulate DNA damage and/or damage repair, possibly through a mechanism that affects mitochondria.  相似文献   
79.
80.
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