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   12279篇
  免费   917篇
  国内免费   36篇
耳鼻咽喉   73篇
儿科学   387篇
妇产科学   204篇
基础医学   1671篇
口腔科学   183篇
临床医学   1164篇
内科学   2639篇
皮肤病学   150篇
神经病学   1071篇
特种医学   416篇
外科学   1727篇
综合类   254篇
一般理论   9篇
预防医学   1090篇
眼科学   299篇
药学   886篇
中国医学   46篇
肿瘤学   963篇
  2023年   59篇
  2022年   94篇
  2021年   252篇
  2020年   153篇
  2019年   248篇
  2018年   267篇
  2017年   208篇
  2016年   251篇
  2015年   268篇
  2014年   417篇
  2013年   527篇
  2012年   867篇
  2011年   877篇
  2010年   444篇
  2009年   442篇
  2008年   703篇
  2007年   842篇
  2006年   781篇
  2005年   786篇
  2004年   715篇
  2003年   686篇
  2002年   628篇
  2001年   143篇
  2000年   115篇
  1999年   133篇
  1998年   135篇
  1997年   138篇
  1996年   97篇
  1995年   102篇
  1994年   84篇
  1993年   91篇
  1992年   91篇
  1991年   63篇
  1990年   90篇
  1989年   81篇
  1988年   73篇
  1987年   63篇
  1986年   66篇
  1985年   75篇
  1984年   69篇
  1983年   57篇
  1982年   59篇
  1981年   63篇
  1980年   60篇
  1979年   50篇
  1978年   46篇
  1974年   36篇
  1973年   42篇
  1972年   39篇
  1968年   32篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Antibody Conjugates for the Treatment of Cancer   总被引:3,自引:0,他引:3  
  相似文献   
22.
23.
The use of the radial artery as an alternative vascular conduit for coronary bypass surgery has become increasingly popular. The plastic surgery experience with radial forearm flaps has shown that sacrifice of the radial artery is not always a benign maneuver. The potential morbidity after using this conduit donor site in terms of hand dysfunction or wound healing problems can be significant, and frequently must ultimately be addressed as part of the role of the reconstructive surgeon. Case examples of skin necrosis, subsequent forearm wound infection and hypertrophic scarring after radial artery harvest are presented to introduce this as a real concern and to allow a review of the entire spectrum of potential problems in this regard. Any selection process where the radial artery may be chosen as the coronary revascularization conduit must anticipate these known donor site complications.  相似文献   
24.
 In order to determine the dynamics of hematopoietic cell turnover, proliferative activity and incidence of apoptosis (programmed cell death) were evaluated in bone marrow trephine biopsies. Selection of patients (20 in each group) included in addition to a control group, idiopathic thrombocytopenia (ITP), reactive thrombocytosis (TH), secondary polycythemia-smokers' polyglobuly (PG), primary (essential-hemorrhagic) thrombocythemia (PTH), polycythemia vera (PV), and finally acute myeloid leukemia (AML). Apoptosis was demonstrated by the in situ end-labeling technique (ISEL) and proliferative activity by applying the monoclonal antibody PC10 raised against proliferating cell nuclear antigen (PCNA). To assess dynamic features of hematopoiesis, an index was calculated consisting of the ratio between PCNA-positive nuclei and the apoptotic cell fraction. This factor was termed the hematopoietic turnover index (HTI). Morphometric analysis revealed that the HTI was significantly increased in AML and PV. According to cell culture studies both disorders are characterized by either a prevalent proliferation of the myeloid or erythroid cell mass. On the other hand, PG, PTH, and TH showed no relevant enhancement of this index in comparison to the control specimen. In vitro experiment results are in keeping with the finding that PG and PTH are not associated with a significant expansion of the erythroid lineage (CFU-E). Similar to ITP and TH, in PTH megakaryocyte proliferation (CFU-MEG) is the predominant feature of cell turnover. Differences between PTH and TH are in line with the reduced in vitro formation of CFU-MEG in the latter disorder. In conclusion, our in situ study on turnover rates of the bone marrow in various neoplastic and reactive lesions extends previous experimental data on hematopoietic cell kinetics. Received: 10 March 1997 / Accepted: 18 May 1997  相似文献   
25.
Different assay systems have been used to quantitate lymphokine-induced natural cytotoxic activity as a measure of immune status. This study compares the effects of inducing cytotoxicity in a bulk culture system, where effector cells are transferred to a micro culture well for assay, to a micro culture system where the effector cells are not transferred. The effector/target ratio for both the bulk and micro culture systems was calculated using the number of viable effector cells present at the time of target cell addition. After overnight incubation with interleukin-2 (IL-2), the lytic activity of murine spleen cells to targets using a micro culture system was increased two-fold over the bulk culture method. This increase was amplified further after 5 days of activation with IL-2, in that the micro culture system resulted in a four-fold increase in cytotoxic activity. The loss of some adherent cells in the bulk culture system did not explain the overall decrease in recovered cytotoxicity. The difference appeared to be related to cell loss during centrifugation. Therefore, the E/T ratios are different in the two systems if not corrected for the number of viable cells.  相似文献   
26.
27.
Thirteen infants, 10 with A-O and 3 with B-O hemolytic disease of the newborn (ABO-HDN), were treated with synthetic A or B blood group trisaccharides (ATS, BTS) which cause dissociation of maternal antibody bound to infant red cells. The clinical outcome was compared with that of a control group of 21 infants treated with phototherapy during the preceding year. Exchange transfusion was required in 2 out of 13 infants in the experimental group and in 7 in the control group. A randomized prospective controlled study is necessary to confirm these results.  相似文献   
28.
PURPOSE: To assess the consistency of ratings assigned by health sciences faculty members relative to community members during an innovative admissions protocol called the Multiple Mini-Interview (MMI). METHOD: A nine-station MMI was created and 54 candidates to an undergraduate MD program participated in the exercise in Spring 2003. Three stations were staffed with a pair of faculty members, three with a pair of community members, and three with one member of each group. Raters completed a four-item evaluation form. All participants completed post-MMI questionnaires. Generalizability Theory was used to examine the consistency of the ratings provided within each of these three subgroups. RESULTS: The overall test reliability was found to be .78 and a Decision Study suggested that admissions committees should distribute their resources by increasing the number of interviews to which candidates are exposed rather than increasing the number of interviewers within each interview. Divergence of ratings was greater within the pairing of community member to faculty member and least for pairings of community members. Participants responded positively to the MMI. CONCLUSION: The MMI provides a reliable protocol for assessing the personal qualities of candidates by accounting for context specificity with a multiple sampling approach. Increasing the heterogeneity of interviewers may increase the heterogeneity of the accepted group of candidates. Further work will determine the extent to which different groups of raters provide equally valid (albeit different) judgments.  相似文献   
29.
30.
Summary The Aspergillus nidulans acetamidase gene (amdS) has been used to transform Penicillium chrysogenum at low frequency. Several transformants were tested and shown to be mitotically stable. Southern blot analysis indicated that transforming DNA had integrated into the chromosomal DNA, possibly at multiple sites.  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