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   3350篇
  免费   230篇
  国内免费   5篇
耳鼻咽喉   57篇
儿科学   128篇
妇产科学   92篇
基础医学   474篇
口腔科学   124篇
临床医学   317篇
内科学   629篇
皮肤病学   26篇
神经病学   274篇
特种医学   127篇
外科学   337篇
综合类   23篇
一般理论   4篇
预防医学   294篇
眼科学   64篇
药学   351篇
中国医学   1篇
肿瘤学   263篇
  2024年   5篇
  2023年   16篇
  2022年   32篇
  2021年   43篇
  2020年   53篇
  2019年   72篇
  2018年   87篇
  2017年   68篇
  2016年   98篇
  2015年   99篇
  2014年   112篇
  2013年   180篇
  2012年   233篇
  2011年   219篇
  2010年   135篇
  2009年   131篇
  2008年   233篇
  2007年   241篇
  2006年   252篇
  2005年   195篇
  2004年   192篇
  2003年   158篇
  2002年   183篇
  2001年   27篇
  2000年   27篇
  1999年   29篇
  1998年   44篇
  1997年   42篇
  1996年   53篇
  1995年   27篇
  1994年   25篇
  1993年   24篇
  1992年   13篇
  1991年   18篇
  1990年   21篇
  1989年   20篇
  1988年   17篇
  1987年   13篇
  1986年   11篇
  1985年   16篇
  1984年   15篇
  1983年   9篇
  1982年   7篇
  1981年   5篇
  1980年   8篇
  1979年   15篇
  1978年   14篇
  1977年   10篇
  1975年   9篇
  1972年   5篇
排序方式: 共有3585条查询结果,搜索用时 15 毫秒
161.
162.

Background  

KRAS mutations represent key alterations in colorectal cancer development and lead to constitutive EGFR signaling. Since EGFR inhibition represents a therapeutic strategy in advanced colorectal cancer, KRAS mutation analysis has quickly been introduced as a treatment-predictive test.  相似文献   
163.
Endothelial progenitor cells (EPCs) and late outgrowth endothelial cells (OECs) seem to play an important role in vessel formation. While EPCs seem to exert their function mainly through a paracrine effect, the OECs can develop into mature endothelial cells and form tubular structures. Exercise is known to increase angiogenic factors that can mobilize EPCs; however, the effect on OECs is not known. We investigated the response to a single session of strenuous exercise on OECs, vascular endothelial growth factor (VEGF) and inflammatory cell levels in the healthy. Eleven healthy subjects performed 1 h of spinning exercise. Blood samples were collected at 1, 6, 24 and 48 h post-exercise for cell culture and biochemical analysis. OEC colonies doubled one hour after the spinning session (baseline 4.5 ± 4.3 vs. 9.0 ± 3.7, P < 0.05). Serum VEGF increased from 194 ± 107 pg/ml at baseline to 224 ± 111 pg/ml after 1 h, p = ns and neutrophilic granulocytes increased from 3.73 ± 1.38 at baseline to 9.08 ± 10.5 at 1 h (P < 0.01). The increased levels of OECs, VEGF and neutrophilic granulocytes declined gradually at the following time points. VEGF levels and neutrophilic granulocytes were highly correlated to OEC levels, r = 0.903 (VEGF) and r = 0.85 (neutrophilic granulocytes), respectively. Strenuous physical activity increases OEC colonies and is correlated to serum VEGF and neutrophilic granulocytes levels. An acute exercise-induced inflammatory response might be responsible for the VEGF release and subsequent increase of OECs. The clinical importance of these findings remains to be elucidated.  相似文献   
164.
165.
166.
167.
Objectives/Hypothesis: The aim of the present study was to determine the incidence of postoperative persisting dysphagia after uvulopalatoplasty performed with conventional steel scalpel (UPP) and to videoradiographically evaluate the oral and pharyngeal phases of swallowing in patients reporting persisting dysphagia. The hypothesis to be tested was that patients treated with UPP would demonstrate a lower incidence of persisting dysphagia than previously found after uvulopalatoplasty performed with laser technique (LUPP). Study Design: Retrospective. Methods: Sixty-eight of 76 consecutive patients treated with UPP answered a questionnaire concerning outcome and late complications after the operation. The patients who reported postoperative dysphagia were additionally interviewed at a minimum of 1 year postoperatively, and the oral and pharyngeal phases of swallowing were videoradiographically examined in those with persisting dysphagia. Results: The incidence of persisting dysphagia after UPP was 29%. Videoradiographically 71% of the dysphagic patients showed a deviant pharyngeal swallowing pattern. Conclusion: The incidence of persisting dysphagia after UPP did not differ from that reported after laser uvulopalatoplasty. Dysphagia after UPP was mostly associated with videoradiographic signs of deviant pharyngeal swallowing function. Patients should be informed that there is a risk of developing dysphagia after uvulopalatoplasty.  相似文献   
168.
The association between parity and risk of thyroid cancer was examined in a case-control study nested within a cohort of Swedish women born 1925–60. A total of 1,409 cases of thyroid cancer were compared with 7,019 agematched controls. Odds ratios (OR) and 95 percent confidence intervals (CI) were calculated as estimates of relative risk. A weak association was found between parity and risk of thyroid cancer (OR for ever-parous women cf nulliparous was 1.1, CI=1.0–1.3). For the subset of papillary cancers, there was a significantly increased risk (OR for ever-parous cf nulliparous = 1.3, CI=1.0–1.6), and among women diagnosed at the age of 50 or older, there was a positive linear trend with increasing number of livebirths. Women during the first year after a livebirth had an increased risk of thyroid cancer compared with women who delivered 10 or more years before; this association was most prominent among uniparous women (OR=2.5, CI=1.1–5.9). An increased risk was also apparent for age over 20 years at livebirth (among uniparous women) and age over 25 years at last livebirth (among multiparous women). A negligible effect of parity on thyroid cancer risk was seen, but each livebirth may have a short-term and age-dependent promoting effect.Authors are with the Department of Cancer Epidemiology, University Hospital, Uppsala, Sweden (M.R. Galanti, M. Lambe, A. Ebbora, R. Sparda B. Pettersson): Department of Social Medicine, University Hospital, Uppsala, Sweden (M. Lambe); Department of Epidemiology, Harvard School of Public Health, Boston, USA (A. Ekbom). Address correspondence to Dr M. Rosaria Galanti, Department of Cancer Epidemiology, University Hospital, S-751 85 Uppsala, Sweden. This work was supported in part by grant n. 3136-B92-02XBB from the Swedish Cancer Society.  相似文献   
169.
170.
BACKGROUND: Morphological evaluation of kidney biopsies applying the Banff Classification is closely correlated to clinical parameters of rejection. However, this classification is insufficient for monitoring the effect of instituted anti-rejection therapy. The objective of the present study was to develop a diagnostic tool enabling rapid assessment of the effects of an attempted anti-rejection treatment. MATERIALS AND METHODS: A kidney allotransplantation model in the rat was applied. All animals were initially maintained on cyclosporine A (CsA). In order to induce an episode of acute cellular rejection, CsA was withdrawn for 5 days. Thereafter, the immunosuppressive treatment was restarted. Core biopsies were taken before, and at various times after, the introduction of anti-rejection therapy. Infiltrating cells were isolated using an in vitro culture system, allowing cells to propagate from the biopsies to culture medium. Propagated cells were counted and analysed for subtype and activation markers using flow cytometry. The results were compared with immunohistochemical and morphological analyses of the grafts. RESULTS: By applying the in vitro culture system it was possible to demonstrate a reduction in outgrowth of mononuclear cells from core biopsies as early as 2 days after the start of anti-rejection therapy. At this time-point, as well as 2 days later, morphological and immunohistochemical analyses of biopsies showed ongoing acute cellular rejection, with no differences between biopsies taken before and after restart of CsA-therapy. The percentage of propagating T lymphocytes expressing the activation markers CD25 or MHC class II did not differ between grafts with ongoing rejection and grafts obtained from CsA-treated rats, neither did the ratio of CD4/CD8-positive cells. CONCLUSION: Our findings indicate that the ex vivo propagation method could function as a complement to routine histology, not only in the diagnosis of cellular rejection but also in order to rapidly reveal a failure of an anti-rejection therapy to halt the rejection process.  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