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   46134篇
  免费   2255篇
  国内免费   181篇
耳鼻咽喉   676篇
儿科学   1025篇
妇产科学   871篇
基础医学   5870篇
口腔科学   3259篇
临床医学   3176篇
内科学   11564篇
皮肤病学   1080篇
神经病学   3642篇
特种医学   924篇
外科学   6833篇
综合类   254篇
一般理论   13篇
预防医学   3528篇
眼科学   846篇
药学   2445篇
  3篇
中国医学   196篇
肿瘤学   2365篇
  2024年   124篇
  2023年   361篇
  2022年   802篇
  2021年   1676篇
  2020年   908篇
  2019年   1269篇
  2018年   1544篇
  2017年   961篇
  2016年   1106篇
  2015年   1347篇
  2014年   1950篇
  2013年   2297篇
  2012年   3770篇
  2011年   4001篇
  2010年   2245篇
  2009年   1860篇
  2008年   3212篇
  2007年   3248篇
  2006年   3096篇
  2005年   2940篇
  2004年   2513篇
  2003年   2233篇
  2002年   1997篇
  2001年   221篇
  2000年   167篇
  1999年   246篇
  1998年   314篇
  1997年   244篇
  1996年   215篇
  1995年   207篇
  1994年   159篇
  1993年   126篇
  1992年   117篇
  1991年   96篇
  1990年   61篇
  1989年   49篇
  1988年   48篇
  1987年   46篇
  1986年   49篇
  1985年   59篇
  1984年   63篇
  1983年   61篇
  1982年   46篇
  1981年   53篇
  1980年   66篇
  1979年   33篇
  1978年   39篇
  1977年   49篇
  1976年   29篇
  1973年   21篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
One of the side-effects of ketamine abuse is genito-urinary damage. This report describes a case of a former ketamine user who presented with urinary symptoms associated with ketamine years after stopping consumption. This was a 26-year-old male with a history of ketamine abuse. He started treatment for alcohol dependence at age 19. He smoked marijuana daily and denied any other drug use. During the follow-up, urinary symptoms were evidenced (dysuria, frequency, urgency, incontinence, nocturia, hematuria, and suprapubic pain). Urinary symptoms started two years ago and worsened over time. The patient was referred to a urologist. A cystoscopy revealed lesions compatible with interstitial cystitis like the ones that appear in some ketamine abusers. Given the medical history, the urologist asked him about ketamine consumption and the patient declared a daily use of 50 milligrams intranasally from age 15 to age 17. Given these findings, not reported previously in the medical literature, future research should follow up patients who at some point in their life made an abusive consumption of ketamine in order to understand the pathogenesis and to be able to intervene before clinical disease manifests itself.  相似文献   
12.
13.
14.
15.
16.
17.
BK virus is the causative agent of polyomavirus-associated nephropathy, a major cause of kidney transplant failure affecting 1%-10% of recipients. Previous studies that investigated the viral source on the kidney recipient pointed that the donor is implicated in the origin of human polyomavirus BK (BKPyV) infection in recipients, but giving the low genetic variability of BKPyV this subject is still controversial. The aim of this study was to determine if BKPyV replicating in kidney recipients after transplantation is always originated from the donor. Urine and blood samples from 68 pairs of living donors and kidney recipients who underwent renal transplantation from August 2010-September 2011 were screened for BKPyV by real time polymerase chain reaction. Only three recipients presented viremia. When both donors and recipients were BKPyV positive, a larger fragment of VP1 region was obtained and sequenced to determine the level of similarity between them. A phylogenetic tree was built for the 12 pairs of sequences obtained from urine and high level of similarity among all sequences was observed, indicating that homology inferences for donor and recipient viruses must be cautiously interpreted. However, a close inspection on the donor-recipient pairs sequences revealed that 3 of 12 pairs presented considerably different viruses and 4 of 12 presented mixed infection, indicating that the source of BKPyV infection is not exclusively derived from the donor. We report that about 60% of the renal recipients shed BKPyV genetically distinct from the donor, confronting the accepted concept that the donor is the main source of recipients’ infection.  相似文献   
18.
It has been reported that low-plasma cytomegalovirus (CMV) DNA loads are associated with an increased risk of overall mortality in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Utilizing a conservative strategy for initiation of preemptive antiviral therapy (>1500 IU/mL), we characterized the virological features of spontaneously-resolving episodes of CMV DNAemia and assessed their impact on mortality through the first year after transplantation. We reviewed the CMV DNA polymerase chain reaction results and clinical charts of 230 consecutive adult patients who underwent T-cell replete allo-HSCT at our center. A total of 280 episodes of CMV DNAemia were registered in 164 patients, of which 144 episodes cleared spontaneously. Clearance of CMV DNAemia was significantly delayed in initial and recurrent self-resolving episodes featuring CMV DNA peak loads > 250 IU/mL compared with those displaying lower values. All-cause mortality in patients with self-resolving episodes of CMV DNAemia was comparable (P = 0.7) to that in patients with no CMV DNAemia and was not related to the CMV DNA peak load (≥250 IU/mL vs <250 IU/mL) (P = 0.6). In summary, in our setting, the magnitude of the CMV DNA peak load reached during self-resolving episodes of CMV DNAemia correlated directly with duration of episodes, but had no apparent impact on all-cause mortality taking patients with no documented CMV DNAemia as a reference.  相似文献   
19.
Infection with human papillomavirus (HPV) is the main cause of cervical cancer. Viral persistence is considered the main risk factor for neoplastic progression and evidence suggests that regulatory T cells (Treg) play an important role in the failure of viral elimination. The aim of this study was to detect phenotypic markers of Treg and cytokines interleukin (IL)-10 and transforming growth factor (TGF)-β, in the cervical microenvironment of HPV-infected patients. One hundred and one samples of uterine cervix embedded in paraffin were analyzed. We used immunohistochemistry to examine the coexpression of the CD25/FOXP3 and CD4/TGF-β markers, and the expression of GITR and IL-10 in cells present in the cervical stroma. We detected a microenvironment composed of high proportions of CD25+FOXP3+, CD4+TGFβ+, IL-10+, and GITR+ cells in samples with high viral loads and severe lesions of HPV-infected patients. The abundance of these markers, indicative of the presence of Treg cells and immunosuppressive cytokines, was significantly associated with severe lesions and elevated viral loads in the examined samples. These results suggest that Treg cells may be involved in maintaining a microenvironment favorable for viral persistence and neoplastic progression. Our findings support those of previous studies that suggested that these markers could be used to predict HPV persistence and neoplastic progression, and as potential targets for immune response modulation.  相似文献   
20.
Parasitology Research - Integrative taxonomy uses several sources of information to establish more robust species delimitation criteria. In this study, we followed that approach to describe two new...  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