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   1075篇
  免费   44篇
  国内免费   14篇
耳鼻咽喉   6篇
儿科学   56篇
妇产科学   9篇
基础医学   124篇
口腔科学   15篇
临床医学   59篇
内科学   216篇
皮肤病学   58篇
神经病学   128篇
特种医学   68篇
外科学   115篇
综合类   2篇
预防医学   48篇
眼科学   8篇
药学   116篇
中国医学   2篇
肿瘤学   103篇
  2023年   8篇
  2022年   16篇
  2021年   21篇
  2020年   7篇
  2019年   17篇
  2018年   17篇
  2017年   12篇
  2016年   19篇
  2015年   12篇
  2014年   24篇
  2013年   35篇
  2012年   35篇
  2011年   30篇
  2010年   32篇
  2009年   31篇
  2008年   30篇
  2007年   53篇
  2006年   41篇
  2005年   43篇
  2004年   36篇
  2003年   36篇
  2002年   42篇
  2001年   42篇
  2000年   47篇
  1999年   40篇
  1998年   31篇
  1997年   26篇
  1996年   19篇
  1995年   14篇
  1994年   8篇
  1993年   15篇
  1992年   28篇
  1991年   27篇
  1990年   24篇
  1989年   25篇
  1988年   18篇
  1987年   25篇
  1986年   19篇
  1985年   6篇
  1984年   20篇
  1983年   11篇
  1982年   14篇
  1981年   7篇
  1980年   8篇
  1979年   11篇
  1977年   6篇
  1975年   6篇
  1974年   7篇
  1971年   4篇
  1970年   5篇
排序方式: 共有1133条查询结果,搜索用时 31 毫秒
1.
2.
3.
Thirteen new 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(4-aroyl-thiocarbamoyl- 1 piperazinyl)-3-quinoline carboxylic acids were prepared, Their structures were characterized by elemental analysis, IR, HNMR and MS spectra.Preliminary pharmacological tests indicated that some of compounds Ia~m possess strong inhibiting activity against Escherichia coli, Bacillus subtilis and Proteus at concentration of 100 μg/ml.  相似文献   
4.
We describe a novel human zinc finger cNDA, C2H2-171. This cDNA represents an mRNA which encodes a protein of 484 amino acids and a calculated molecular weight of 54 kD. Four zinc finger-like domains are found in the C-terminal end of the protein. At the N-terminus, C2H2-171 contains a POZ/tramtrack-like domain similar to that found in the tumor associated zinc finger proteins LAZ-3/BCL-6 and PLZ-F, as well as in non-zinc finger proteins. C2H2-171 RNA is preferentially expressed in the brain, and increases during the course of murine development, with maximal expression in the adult. C2H2-171 RNA is differentially expressed in brain regions, with the highest level of expression in the cerebellum. C2H2-171 RNA was expressed at high levels in primary cerebellar granule cell neurons compared to astrocytes. The gene encoding C2H2-171 is highly conserved in vertebrates, and maps to the terminus of human chromosome 1 (1q44-ter). This chromosomal location is associated with a number of cytogenetic aberrations including those involving brain developmental anomalies and tumorigenesis. These data suggest that C2H2-171 may play an important role in vertebrate brain development and function.  相似文献   
5.
6.
7.
OBJECTIVE: The aim was to investigate the effect of pubertal development on serum levels of growth hormone binding protein (GHBP) and IGF-I, and to study the relationship between GHBP levels and height standard deviation score (SDS), nutritional state and IGF-I levels. DESIGN AND PATIENTS: The investigation was performed on serum samples from 72 healthy adolescents of different pubertal stage. Results were compared to those obtained in 46 prepubertal children. MEASUREMENTS: Serum levels of GHBP were measured by HPLC gel filtration and IGF-I levels were measured by RIA after acid-ethanol extraction. RESULTS: No effect of pubertal stage on serum levels of GHBP was found. A positive relationship was found between serum levels of GHBP and height SDS (r = 0.38; P < 0.005) and weight expressed as percentage of median weight for height age (r = 0.46; P < 0.0005). Serum levels of IGF-I increased during puberty and were not correlated with height SDS or weight for height age. In pubertal subjects, no relationship existed between serum levels of GHBP and IGF-I. In prepubertal subjects, however, a significantly positive relationship between GHBP and IGF-I levels (r = 0.66; P < 0.0005) was found. CONCLUSIONS: Pubertal development does not seem to influence serum levels of GHBP. Height SDS and nutritional state are related to the concentration of GHBP. Before puberty, the level of GHBP is positively related to IGF-I levels; during puberty, however, the increase in serum IGF-I levels is not accompanied by changes in the amount of circulating GHBP.  相似文献   
8.
Torsional properties of the Canal Master instrument.   总被引:2,自引:0,他引:2  
The torsional properties of a new type of endodontic hand instrument, the Canal Master, were compared with conventional machined K-type endodontic files. Sizes 20 through 50 were tested in clockwise (CW) and counterclockwise (CCW) directions. Canal Master instruments exhibited significantly less torque at yield and at failure in both the CW and CCW directions. Rotation at failure was significantly greater for the Canal Master instruments in both CW and CCW directions. There was no significant difference in either torque or the amount of rotation for the Canal Master instruments when comparing CW versus CCW rotation. There was no clinically visible evidence of deformation of the Canal Master instruments prior to torsional failure.  相似文献   
9.
10.
Arguably, nursing, like all health care disciplines, is an applied science. Essentially, this refers to the application of theory in order to understand and respond to the health problems of clients. These theories may be drawn (borrowed) from any applied science, or generated inductively from clinical nursing practice. Alternatively, nurses may attempt to apply deductive theory (global theoretical frameworks) known as nursing models. In this paper, all theoretical approaches, irrespective of origin, are referred to as models used by nurses. Thirteen criteria by which clinicians, and others, can evaluate the clinical and practical utility of models used by nurses which are expressed in the form of questions are identified and discussed. The criteria are an extension, both in detail and in number, of those developed by Reynolds and Cormack and subsequently applied by those writers to the Johnson Behavioural System Model of Nursing. The value, or otherwise, of individual models, or of models in general, will not be discussed in this paper. However, the authors propose that if the evaluation criteria described here are applied to existing models, serious deficits will be identified in relation to their clinical and practical utility.  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