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   3689篇
  免费   184篇
  国内免费   29篇
耳鼻咽喉   41篇
儿科学   134篇
妇产科学   65篇
基础医学   489篇
口腔科学   377篇
临床医学   205篇
内科学   759篇
皮肤病学   50篇
神经病学   303篇
特种医学   348篇
外科学   283篇
综合类   23篇
预防医学   395篇
眼科学   65篇
药学   258篇
中国医学   38篇
肿瘤学   69篇
  2023年   42篇
  2022年   64篇
  2021年   114篇
  2020年   67篇
  2019年   98篇
  2018年   115篇
  2017年   75篇
  2016年   88篇
  2015年   105篇
  2014年   138篇
  2013年   172篇
  2012年   209篇
  2011年   240篇
  2010年   166篇
  2009年   133篇
  2008年   204篇
  2007年   196篇
  2006年   155篇
  2005年   147篇
  2004年   92篇
  2003年   92篇
  2002年   127篇
  2001年   67篇
  2000年   53篇
  1999年   60篇
  1998年   67篇
  1997年   49篇
  1996年   72篇
  1995年   50篇
  1994年   49篇
  1993年   45篇
  1992年   37篇
  1991年   40篇
  1990年   26篇
  1989年   40篇
  1988年   46篇
  1987年   36篇
  1986年   31篇
  1985年   46篇
  1984年   30篇
  1983年   30篇
  1982年   30篇
  1981年   27篇
  1980年   15篇
  1979年   5篇
  1978年   13篇
  1977年   29篇
  1976年   21篇
  1975年   18篇
  1967年   4篇
排序方式: 共有3902条查询结果,搜索用时 15 毫秒
51.
Multidrug-resistant tuberculosis (MDR-TB) is an emerging and worrisome health problem that threatens tuberculosis (TB) control worldwide. The clinical management of MDR-TB is a complex issue associated with the use of multiple drugs for a long period, usually accompanied by side effects and high costs. The objective of this work was to relate cases of MDR-TB occurring in Goiás, a central state of Brazil. We related five cases of MDR-TB, three women and two men. All were pulmonary cases. Three were in their second treatment and two in their first treatment. Surgical pulmonary resection was performed in one case. One death occurred. Lack of adherence, gastric intolerance to anti-TB drugs and poor clinical management were the main aspects related to the emergent resistance. A revision of the main clinical aspects of this disease was performed.  相似文献   
52.
53.
After orthotopic heart transplantation (OHT), the allograft undergoes characteristic alterations in myocardial structure, including hypertrophy, increased ventricular stiffness, ischemia, and inflammation, all of which may decrease overall graft survival. Methods to quantify these phenotypes may clarify the pathophysiology of progressive graft dysfunction post-OHT. We performed cardiac magnetic resonance (CMR) with T1 mapping in 26 OHT recipients (mean age 47?±?7 years, 30?% female, median follow-up post-OHT 6 months) and 30 age-matched healthy volunteers (mean age 50.5?±?15 years; LVEF 63.5?±?7?%). OHT recipients had a normal left ventricular ejection fraction (LVEF 65.3?±?11?%) with higher LV mass relative to age-matched healthy volunteers (114?±?27 vs. 85.8?±?18 g; p?<?0.001). There was no late gadolinium enhancement in either group. Both myocardial extracellular volume fraction (ECV) and intracellular lifetime of water (τic), a measure of cardiomyocyte hypertrophy, were higher in patients post-OHT (ECV: 0.39?±?0.06 vs. 0.28?±?0.03, p?<?0.0001; τic: 0.12?±?0.08 vs. 0.08?±?0.03, p?<?0.001). ECV was associated with LV mass (r?=?0.74, p?<?0.001). In follow-up, OHT recipients with normal biopsies by pathology (ISHLT grade 0R) in the first year post-OHT exhibited a lower ECV relative to patients with any rejection ≥2R (0.35?±?0.02 for 0R vs. 0.45?±?0, p?<?0.001). Higher ECV but not LVEF was significantly associated with a reduced rejection-free survival. After OHT, markers of tissue remodeling by CMR (ECV and τic) are elevated and associated with myocardial hypertrophy. Interstitial myocardial remodeling (by ECV) is associated with cellular rejection. Further research on the impact of graft preservation and early immunosuppression on tissue-level remodeling of the allograft is necessary to delineate the clinical implications of these findings.  相似文献   
54.
55.
56.
Diabetes mellitus is the leading cause of end-stage renal disease, and uncontrolled hyperglycemia is directly related to the increased mortality in this setting. As kidney function decreases, it becomes more challenging to control blood glucose since the risk of hypoglycemia increases. Decreased appetite, changes in glycaemia homeostasis, along with reduced renal excretion of anti-hyperglycemic drugs tend to facilitate the occurrence of hypoglycemia, despite the paradoxical occurrence of insulin resistance in advanced kidney disease. Thus, in patients using insulin and/or oral anti-hyperglycemic agents, dynamic adjustments with drug dose reduction or drug switching are often necessary. Furthermore, in addition to consider these pharmacokinetics alterations, it is of utmost importance to choose drugs with proven cardio-renal benefits in this setting, such as sodium-glucose co-transporter 2 inhibitors and glucagon-like peptide 1 receptor agonists. In this review, we summarize the indications and contraindications, titration of doses and side effects of the available anti-hyperglycemic agents in the presence of advanced diabetic kidney disease (DKD) and dialysis, highlighting the risks and benefits of the different agents. Additionally, basic renal function assessment and monitoring of glycemic control in DKD will be evaluated in order to guide the use of drugs and define the glycemic targets to be achieved.  相似文献   
57.
58.
59.
The records of 292 patients who were admitted to a teaching hospital from 1984 to 1990 in Uberlandia in southeastern Brazil after being bitten by snakes of the genus Bothrops were retrospectively surveyed. The patients were from 42 municipalities in three states of Brazil. Most (42%) bites occurred between 4:00 PM and 10:00 PM. Fourteen percent of the bites occurred in the month of April. In 54 (18%) of the cases, the snakes were captured and identified as belonging to the following species: B. moojeni (29), B. neuwiedi (18), and Bothrops species (7). A diagnosis was made based on clinical findings in 238 (82%) cases. The lower limbs were the commonest site of bite (74%). The median time interval between bite and admission to the hospital was 3 hr. Fang marks were recorded in 58% of the cases and swelling was recorded in 82%. Clotting time was greater than 15 min in (142 of 264) 54% of the cases. A tourniquet was used on 44 cases. The mean +/- SD dose of specific antivenom used was 187.48 +/- 93.44 mg. The complications that occurred included abscess formation in 18% of the cases, necrosis in 16%, and renal failure in 5%. Amputation was performed in three (1%) cases. The case fatality rate was also 1% (three cases). When all cases were analyzed, the chi-square test for trend showed an increased susceptibility of renal failure with age (P < 0.04). Clotting time greater than 15 min was associated with the development of abscesses (P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
60.
The polymorphic merozoite surface protein-2 (MSP-2) of Plasmodium falciparum is a major malaria-vaccine candidate. In the present study, PCR and hybridization with allelic-specific probes were used to type the Msp-2 gene from isolates from hypo-endemic Brazil (N = 113), meso-endemic Vietnam (N = 208) and holo-endemic Tanzania (N = 67). The typing methods were designed to group isolates into the dimorphic allelic families FC27 and IC1 and to detect possible between-family recombination events. The analysis was complemented by a comparison of 156 Msp-2 sequences from the GenBank database with 12 additional sequences obtained during the present study. Statistically significant differences were detected in pair-wise comparisons of the distribution of Msp-2 allelic types in Brazil and Vietnam, and in Brazil and Tanzania, but not in Vietnam and Tanzania. The extent of allelic diversity in the Msp-2 gene, as estimated by the total number of different alleles found in a given parasite population and the mean multiplicity of infections, clearly paralleled the levels of malaria endemicity in the study areas. However, no correlation between age and multiplicity of infections was found in the subjects. The patterns of Msp-2 diversity in Brazil appeared to be temporally stable, since no significant difference was observed in the distribution of Msp-2 allelic types among isolates collected, 10--13 years apart, in the same area of Rond?nia. Despite the extensive sequence diversity found in Msp-2 alleles, especially in the central repetitive region of the molecule, several instances of identical or nearly identical alleles were found among isolates from different countries and regions, possibly as a result of extensive homoplasy. No recombinant allele was detected by molecular typing in any of the study sites, and the GenBank database included only 12 recombinant sequences (representing 7% of all reported Msp-2 sequences), all of them with an IC1-type 5' end and an FC27-type 3' end. A single, putative, crossover site was characterised for all recombinant alleles. Most of the allelic diversity observed was therefore attributable to variation in the repetitive region of the gene, instead of recombination between alleles of dimorphic families (as commonly found, for example, in the Msp-1 gene). The implications of these findings for studies on the genetic and antigenic diversity of malarial parasites are discussed.  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