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   2438篇
  免费   177篇
  国内免费   3篇
耳鼻咽喉   9篇
儿科学   69篇
妇产科学   44篇
基础医学   460篇
口腔科学   69篇
临床医学   235篇
内科学   483篇
皮肤病学   108篇
神经病学   241篇
特种医学   93篇
外科学   225篇
综合类   29篇
预防医学   172篇
眼科学   33篇
药学   166篇
中国医学   5篇
肿瘤学   177篇
  2023年   17篇
  2022年   34篇
  2021年   52篇
  2020年   32篇
  2019年   44篇
  2018年   60篇
  2017年   48篇
  2016年   59篇
  2015年   67篇
  2014年   85篇
  2013年   101篇
  2012年   145篇
  2011年   134篇
  2010年   76篇
  2009年   63篇
  2008年   109篇
  2007年   117篇
  2006年   109篇
  2005年   100篇
  2004年   86篇
  2003年   86篇
  2002年   86篇
  2001年   57篇
  2000年   57篇
  1999年   55篇
  1998年   22篇
  1997年   18篇
  1996年   25篇
  1995年   17篇
  1993年   16篇
  1992年   36篇
  1991年   36篇
  1990年   42篇
  1989年   32篇
  1988年   38篇
  1987年   35篇
  1986年   40篇
  1985年   31篇
  1984年   30篇
  1983年   36篇
  1982年   24篇
  1979年   23篇
  1978年   17篇
  1975年   19篇
  1974年   17篇
  1973年   17篇
  1972年   19篇
  1969年   15篇
  1968年   16篇
  1967年   13篇
排序方式: 共有2618条查询结果,搜索用时 15 毫秒
41.
Flow cytofluorimetry and statmokinetic method were used to study the circadian rhythm of bone marrow proliferation in Pliss' lymphosarcoma-bearing and intact rats. These data were compared to those obtained in the study of the mitotic activity of the bone marrow in cancer patients. It was found that, already at early stage, tumor affected the circadian rhythm of bone marrow proliferation, reducing the amplitude of oscillations. A model simulating formation of the circadian rhythm of the bone marrow was suggested basing on the possibility to arrest cells at the end of G1 phase. The rate of transition of G1 cells to S phase was determined not only by endogenous "set-points" of the rhythm which formed the basic wave of proliferation but also by conditions of animal upkeep.  相似文献   
42.
To keep pace with increasing competition, the private physician is encouraged to consider a patient education program as a marketing tool. Meeting the educational needs of patients is presented as an opportunity to create a trusting environment in the practice, enhance the doctor-patient relationship, and increase the active role of the patient in the health care process. A management model is proposed for successfully planning, organizing, staffing, leading, and controlling the patient education program.  相似文献   
43.
44.
45.
Summary The main dolichol diphosphate-bound oligosaccharides present in primary cultures of both normal and tumor mouse mammary epithelial cells had the same size, yielded the same pattern after acetolysis and paper chromatography, had the same number of mannose residues susceptible to-mannosidase degradation, and were composed of the same monosaccharide residues. This is the first demonstration that normal and tumor mammary cells have dolichol diphosphate-bound oligosaccharides with very similar, if not identical, structures. These compounds are intermediates in the synthesis of asparagine-linked oligosaccharides. On the other hand, normal and tumor cells showed differences in the specific activities of the enzymes involved in the transfer of the distal monosaccharides from the sugar nucleotides to glycoproteins. Sialyl- and fucosyl-transferases were elevated and galactosyl- and N-acetylglucosaminyltransferases were diminished in mammary tumor cells. The intact tumor cells showed an increased fucosylation of glycoproteins of the asparagine-linkage type. Address for reprints: Roberto L. Ceriani, M.D., Ph.D., Bruce Lyon Memorial Research Laboratory, Children's Hospital Medical Center, 51st and Grove Streets, Oakland, CA 94609, USA.  相似文献   
46.
47.
The “exposome” is a term recently used to describe all environmental factors, both exogenous and endogenous, which we are exposed to in a lifetime. It represents an important tool in the study of autoimmunity, complementing classical immunological research tools and cutting-edge genome wide association studies (GWAS). Recently, environmental wide association studies (EWAS) investigated the effect of environment in the development of diseases. Environmental triggers are largely subdivided into infectious and non-infectious agents. In this review, we introduce the concept of the “infectome”, which is the part of the exposome referring to the collection of an individual's exposures to infectious agents. The infectome directly relates to geoepidemiological, serological and molecular evidence of the co-occurrence of several infectious agents associated with autoimmune diseases that may provide hints for the triggering factors responsible for the pathogenesis of autoimmunity. We discuss the implications that the investigation of the infectome may have for the understanding of microbial/host interactions in autoimmune diseases with long, pre-clinical phases. It may also contribute to the concept of the human body as a superorganism where the microbiome is part of the whole organism, as can be seen with mitochondria which existed as microbes prior to becoming organelles in eukaryotic cells of multicellular organisms over time. A similar argument can now be made in regard to normal intestinal flora, living in symbiosis within the host. We also provide practical examples as to how we can characterise and measure the totality of a disease-specific infectome, based on the experimental approaches employed from the “immunome” and “microbiome” projects.  相似文献   
48.
The health care industry, in particular the hospital industry, is under an increasing degree of pressure, by an ageing population, advancing expensive medical technology a shrinking labor. The pressure on hospitals is further increased by the planned budget cuts in public spending by many current administrations as a result of the economic and financial crises. However, productivity increases may alleviate these problems. Therefore we study whether productivity in the hospital sector is growing, and whether this productivity growth can be influenced by government policy. Using an econometric time series analysis of the hospital sector in the Netherlands, productivity is estimated for the period 1972–2010. Then, productivity is linked to the different regulation regimes during that period, ranging from output funding in the 1970s to the current liberalized hospital market. The results indicate that the average productivity of the hospital sector in different periods differs and that these differences are related to the structure of regulation in those periods.  相似文献   
49.
50.
Our previous studies showed the effects of aqueous and ethanol extracts of Anethum graveolens L. (dill) on female infertility. In the present study we investigated whether different fractions of this herb extract can cause infertility in rats. Female rats were divided into the control groups, the groups receiving either a low (0.5 g/kg)) or a high dose (5g/kg) of water, N-butanol, chloroform and ether fractions of the aqueous plant extract, and the groups receiving either a low (0.045 g/kg) or a high dose (0.45 g/kg) of the same fractions of ethanol extract. The mentioned doses were gavaged in 1mL for 10 days. Vaginal smears were prepared daily. Estradiol and progesterone levels were measured. The left oviduct and ovary were removed, their tissue subsequently being prepared in form of histology slides and stained using haematoxylin-eosin and Masson''s trichrome. Female rats assigned to each group were mated with males; after that, crown-rump lengths and weights of newborn rats were measured. Results showed that each fraction produced some changes such as hormonal level reduction (chloroform fraction), diestrus phase prolongation and infertility (water fraction), and increase in pregnancy duration (chloroform and ether fractions). We concluded that each fraction comprises only some of the mentioned components and therefore recommended the usage of crude extract, especially the aqueous one, in case infertility aims to be induced.  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