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   2515篇
  免费   131篇
  国内免费   12篇
耳鼻咽喉   29篇
儿科学   182篇
妇产科学   49篇
基础医学   258篇
口腔科学   34篇
临床医学   206篇
内科学   406篇
皮肤病学   61篇
神经病学   144篇
特种医学   199篇
外科学   268篇
综合类   117篇
预防医学   107篇
眼科学   32篇
药学   291篇
中国医学   20篇
肿瘤学   255篇
  2022年   27篇
  2021年   65篇
  2020年   26篇
  2019年   55篇
  2018年   50篇
  2017年   31篇
  2016年   81篇
  2015年   105篇
  2014年   94篇
  2013年   96篇
  2012年   113篇
  2011年   140篇
  2010年   94篇
  2009年   72篇
  2008年   98篇
  2007年   80篇
  2006年   87篇
  2005年   80篇
  2004年   81篇
  2003年   65篇
  2002年   62篇
  2001年   49篇
  2000年   53篇
  1999年   55篇
  1998年   40篇
  1997年   48篇
  1996年   47篇
  1995年   37篇
  1994年   37篇
  1993年   27篇
  1992年   32篇
  1991年   25篇
  1990年   40篇
  1989年   52篇
  1988年   51篇
  1987年   40篇
  1986年   44篇
  1985年   37篇
  1984年   33篇
  1983年   33篇
  1982年   16篇
  1980年   14篇
  1979年   25篇
  1977年   17篇
  1976年   15篇
  1974年   22篇
  1972年   17篇
  1971年   17篇
  1968年   17篇
  1967年   15篇
排序方式: 共有2658条查询结果,搜索用时 15 毫秒
1.
In contrast with cross-sectional designs used in previous studies, this exploratory study compared survey data from 127 matched pairs of clinical pharmacists and physicians working together. Physicians' perceptions of the importance of clinical pharmacy activities for patient care and the competence of pharmacists performing the activities were examined for their influence on prescribing behavior in an institutional setting. Data from a national survey showed that physicians rated pharmacists higher regarding recommendations based on drug use evaluations (p = 0.004) and competency to provide all clinical pharmacy services. Scores for pharmacokinetics ratings were similar between pharmacists and physicians (p = 0.168). Pharmacists rated the importance of recommendations based on cost-effectiveness higher than physicians (p = 0.012). Overall, physicians' perceptions of activity importance for patient care and pharmacist competency appear to dictate pharmacists' influence on physician prescribing behavior (R = 0.723).  相似文献   
2.
3.
4.
5.
Karyotypes of 36 lymphoblastoid cell lines established by Epstein-Barr virus (EBV) transformation of peripheral blood lymphocytes (PBL) of eight normal individuals and 28 patients with various nonhematologic malignancies were analyzed. In seven lines (19.4%), cells with trisomy 12 were noted, with clonality in two of these lines. In two of 11 metaphases with such trisomy, chromosome 12 was involved in structural rearrangements [t(8;12)(q12;p12) and t(12;12)(q11;q24)]. No cells with trisomy 12 were observed in phytohemagglutinin (PHA)-stimulated PBL cultures of these individuals. In 250 individuals (normal and with nonhematologic malignancies) examined in our laboratory in the last 5 years, extra copies of chromosome 12 in PHA-stimulated PBL cultures were observed in only five of 23,216 cells (0.02%). There were no cases of clonality in these samples. The frequency of an extra chromosome 12 was comparable to that of the other chromosomes except 21 and X, whose frequency of occurrence was 0.08% and 0.09%, respectively. These findings should be considered random events in PHA-stimulated PBL. On the contrary, in lymphoblastoid cell lines established by EBV transformation, trisomy of chromosome 12 was the most frequent numerical abnormality. It was observed in 64.7% of all cases with chromosome gains and therefore could not be considered a random occurrence. The specificity of this phenomenon for EBV transformation is supported by the results of cytogenetic analysis of eight lymphoblastoid cell lines established by an alternative procedure in our laboratory [1]. In 400 cells analyzed not a single cell with trisomy 12 was observed. We suggest that EBV transformation might either randomly induce formation of such cells in immortalized B-cell populations or show potentially blastomogenic cells or proneness to their formation in certain individuals who could be predisposed to develop lymphoproliferative diseases, especially chronic lymphocytic leukemia (CLL) in which trisomy of chromosome 12 is the most common alteration.  相似文献   
6.
7.
The genomic activity of nucleolar organizer regions (NORs) in eight human B-cell lymphoblastoid cell lines was studied following the routinely used Ag-NOR technique. The results demonstrate that (a) Ag-NORs are located in the short arms of D- and G-group chromosomes, (b) two out of eight cell lines have 66.7% and 49.0% of metaphases, respectively, with 9 to 10 active Ag-NORs, and (c) as a whole, Ag-NOR activity is much higher in B-cell lines as compared with conventional 72-hr peripheral blood lymphocyte (T-cell) harvests.  相似文献   
8.
9.
Epidemiological studies have indirectly linked compounds ofchromium, nickel and arsenic to human carcinogenesis. However,there is no evidence that metal compounds can transform humancells to the tumorigenic phenotype in culture. We show herethat exposure to 36 µM NiS04 for 48–96 h resultsin transformation of an immortal, non-tumorigenic, osteoblast-likecell line, HOS TE85, to the tumorigenic phenotype. Continuouspassaging following treatment leads to the formation of a fewdense foci. The cells isolated and expanded from the foci aremorphologically transformed, and form anchorage-independentcolonies of the size and abundance comparable to that formedby Kirsten murine sarcoma virus transformed HOS TE85 cells.The transformed cells from tumors in nude mice, have enhancedlevels of plasminogen activators and have lost the ability toform model bone matrix on extended culture in the presence ofascorbic acid and ß-glycerophosphate. A number ofcell lines have been established from nude mouse tumors. Cytogeneticanalysis reveals 16 marker chromosomes and an aberrant chromosome16. This is the first report of the transformation of a humancell line to tumorigenic phenotype by a metal carcinogen.  相似文献   
10.
A survey of persons soliciting sex in an area known to be frequented by prostitutes in Albuquerque, NM, included 43 females and 66 males. Seroprevalence rates found in this population-based study were as follows: human immunodeficiency virus type 1 (HIV-1), 3%; hepatitis B, 39%; hepatitis C, 45%. Increased age, intravenous drug use, and condom use were independent risk factors for hepatitis B. Female gender and intravenous drug use were independent risk factors for hepatitis C. Neither sharing injection equipment nor engaging in receptive anal intercourse was independently associated with hepatitis B or C.  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