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   1769篇
  免费   114篇
  国内免费   5篇
耳鼻咽喉   2篇
儿科学   47篇
妇产科学   9篇
基础医学   317篇
口腔科学   30篇
临床医学   176篇
内科学   372篇
皮肤病学   28篇
神经病学   195篇
特种医学   57篇
外科学   177篇
综合类   9篇
预防医学   132篇
眼科学   41篇
药学   165篇
中国医学   4篇
肿瘤学   127篇
  2023年   9篇
  2022年   20篇
  2021年   31篇
  2020年   28篇
  2019年   34篇
  2018年   29篇
  2017年   25篇
  2016年   46篇
  2015年   45篇
  2014年   64篇
  2013年   84篇
  2012年   97篇
  2011年   93篇
  2010年   75篇
  2009年   82篇
  2008年   129篇
  2007年   106篇
  2006年   111篇
  2005年   140篇
  2004年   115篇
  2003年   131篇
  2002年   100篇
  2001年   21篇
  2000年   20篇
  1999年   13篇
  1998年   25篇
  1997年   36篇
  1996年   18篇
  1995年   13篇
  1994年   9篇
  1993年   8篇
  1992年   6篇
  1991年   6篇
  1990年   8篇
  1989年   7篇
  1988年   8篇
  1987年   6篇
  1986年   6篇
  1985年   11篇
  1984年   6篇
  1983年   4篇
  1982年   10篇
  1981年   8篇
  1980年   4篇
  1979年   3篇
  1978年   6篇
  1977年   4篇
  1970年   3篇
  1964年   4篇
  1963年   2篇
排序方式: 共有1888条查询结果,搜索用时 46 毫秒
31.
32.
Serum samples from 94 patients with primary biliary cirrhosis (PBC) and 17 patients with chronic cholestatic hepatitis (CCH) were tested in the fluorometric immunoassay (FIAX) against the non-organ-specific ATPase-associated antigen (M2) and against submitochondrial particles (SMP) and sonicated mitochondria from beef heart and rat liver, to evaluate the specificity and sensitivity of the M2 antigen for the diagnosis of PBC. As controls serum samples from 42 patients with other antimitochondrial antibody (AMA) specificity (against M1, M3, M5, and M6) as well as samples from 417 patients with various other hepatic and non-hepatic disorders were used. Serum samples from 91 of the 94 PBC patients (97%) and all 17 with CCH reacted with the M2 antigen. However, when SMP from rat liver and beef heart were tested in parallel in the FIAX, AMA could be detected in all PBC serum samples. None of the 42 patients with different types of AMA had reactions with the M2 antigen but all had reactions with SMP from rat-liver or beef-heart mitochondria or both. Among the other 417 patients with hepatic and non-hepatic disorders only 4 (1%), all with collagen diseases, had anti-M2 antibodies.  相似文献   
33.
Although results from observational and epidemiological studies suggested a survival benefit associated with high-flux hemodialysis, conclusive evidence from prospective randomized clinical trials has been lacking. Both the HEMO Study in the USA and the Membrane Permeability Outcome Study (MPO Study) in Europe are randomized studies investigating the effect of high- and low-flux hemodialysis on patient outcomes, even though there were some significant differences in the design of the two studies. An earlier randomized clinical trial could not show differences on patient survival between patient groups being treated with membranes of different material and permeability, but this trial was not designed specifically to examine this particular endpoint. Based on these previous experiences, the MPO Study addressed a hemodialysis patient population which was considered to be more susceptible to the intervention with high-flux dialysis. To identify these patients with an elevated risk, low serum albumin levels were chosen as an indicator; low serum albumin is associated with malnutrition, inflammation, atherosclerosis, and with increased risk of morbidity and mortality. Together with low serum albumin, patients had to be new to dialysis to be selected for the MPO Study. These particular considerations on patient selection, together with additional methodological refinements in the study design allow the conclusion that the MPO Study is valid on its own rather than being a European version of the HEMO Study.  相似文献   
34.
OBJECTIVES: Deletion of chromosome 13q [del(13q)] has emerged as a major adverse prognostic factor in multiple myeloma (MM). Del(13q) is detected two to three times more frequently by interphase fluorescence in situ hybridization (FISH) than by metaphase cytogenetics (CG). However, it has remained unclear whether or not del(13q) detected by FISH only provides the same prognostic information as its detection by CG. METHODS: We investigated the outcome of 118 consecutive patients with newly diagnosed MM who were studied by both CG and FISH (RB-1 and/or D13S319 probes). RESULTS: CG revealed informative MM karyotypes in 35 patients (29.7%), with monosomy 13/del(13q) in 16 of them. FISH was indicative for a del(13q) in 43 patients (36.4%). A del(13q) by FISH was present in all 16 patients with monosomy 13/del(13q) by CG and also in four of 19 patients with informative karyotypes and diploid chromosome 13. Furthermore, del(13q) was present by FISH in 23 of 84 patients with diploid/non-informative metaphases by CG. Overall survival of patients with monosomy 13/del(13q) by CG and of patients with del(13q) by FISH only was not significantly different (median, 35.2 months vs. 33.2 months, P = 0.58). In contrast, patients with diploid chromosome 13 by either technique experienced prolonged survival (median, 65.6 months). Presence of abnormal karyotypes was significantly associated with an increased Ki67 growth fraction. CONCLUSION: FISH of chromosome 13q adds prognostic information to that provided by CG. It is suggested to use FISH analysis in clinical trials if risk stratifications take into consideration the chromosome 13q status.  相似文献   
35.
Intracardiac renin is considered to be involved in the pathogenesis of cardiac hypertrophy, fibrosis, and myocardial infarction. Cardiac renin is predominantly derived from the circulation, because preprorenin is not expressed locally and uptake of renin has been demonstrated. One mechanism of internalization recently described involves the mannose-6-phosphate receptor and requires glycosylation of renin. Based on previous observations, we considered the existence of another pathway of uptake, not requiring glycosylation and predominantly involving prorenin. This hypothesis and its functional consequences were investigated in vitro and in vivo. We demonstrate that isolated adult cardiomyocytes internalize unglycosylated prorenin, which is followed by the generation of angiotensins. We further show that transgenic rats, expressing the ren-2(d) renin gene in an inducible manner, exhibit markedly enhanced levels of unglycosylated renin within intracellular compartments in the heart as a consequence of the induction of hepatic transgene expression and the rise of circulating unglycosylated prorenin levels. Because in this model severe cardiac damage occurs as a consequence of the rise of circulating prorenin levels, internalization of prorenin into cardiac cells is likely to play a key role in this process.  相似文献   
36.
ObjectiveTo evaluate outcomes of a registered nurse–led care management intervention for disabled Medicaid beneficiaries with high health care costs.ConclusionsWe found no health care cost savings for disabled Medicaid beneficiaries randomized to intensive care management. Among participants, care management may have the potential to increase access to needed care, slow growth in the number and therefore cost of unplanned hospitalizations, and prevent homelessness. These findings apply to start-up care management programs targeted at high-cost, high-risk Medicaid populations.  相似文献   
37.
38.
We examined whether major depressive disorder (MDD) is associated with a tendency to recall more remote, specific autobiographical memories, particularly in the context of positive memories. To this end, individuals with MDD (n?=?26) and healthy controls (n?=?54) completed the Autobiographical Memory Test. Consistent with the hypothesis, remoteness of specific memories in the MDD group, but not the control group, depended on valence. Compared to the control group, the MDD group recalled more remote positive events. Additionally, the MDD group’s positive specific memories were significantly more remote than their negative specific memories. Retrieving remote positive memories might impair mood regulation and maintain an individual’s negative mood and perpetuate depression.  相似文献   
39.
Taxonomic challenges of seagrasses were met by using 18S ribosomal subunit of ribosomal deoxyribonucleic acid (18S rDNA) sequence data of 14 seagrass species from India and two temperate species from Germany. The phylogenetic trees presented are based on the 18S rDNA sequence analysis of 41 nucleotide sequences including sequences obtained in the present study as well as previously published sequences of freshwater and saltmarsh plants, and seagrasses for identifying the evolutionary lineage. The 18S rDNA data indicates independent origin of temperate and tropical seagrasses with the genus Halophila as the intermediate group for both the regions. Based on the complex morphological structures the Halophila group represents the basal form among seagrasses whereas Enhalus is considered to be the most recently originated seagrass species. In that context, the marine Hydrocharitaceae group of Enhalus, Thalassia and Halophila has been proposed to be separated into two groups such as Enhalus/Thalassia and Halophila subfamilies. Hence, the present systematic studies warrant a revised taxonomy for seagrasses, which better reflects the phylogenetic results obtained from molecular and conventional data.  相似文献   
40.
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