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   10260篇
  免费   730篇
  国内免费   37篇
耳鼻咽喉   77篇
儿科学   293篇
妇产科学   293篇
基础医学   1380篇
口腔科学   234篇
临床医学   1276篇
内科学   2036篇
皮肤病学   259篇
神经病学   1080篇
特种医学   185篇
外科学   896篇
综合类   64篇
一般理论   16篇
预防医学   1306篇
眼科学   181篇
药学   682篇
中国医学   32篇
肿瘤学   737篇
  2024年   16篇
  2023年   132篇
  2022年   225篇
  2021年   463篇
  2020年   263篇
  2019年   359篇
  2018年   377篇
  2017年   273篇
  2016年   314篇
  2015年   316篇
  2014年   393篇
  2013年   579篇
  2012年   829篇
  2011年   821篇
  2010年   472篇
  2009年   372篇
  2008年   632篇
  2007年   620篇
  2006年   569篇
  2005年   540篇
  2004年   455篇
  2003年   438篇
  2002年   389篇
  2001年   42篇
  2000年   34篇
  1999年   39篇
  1998年   68篇
  1997年   68篇
  1996年   60篇
  1995年   51篇
  1994年   40篇
  1993年   45篇
  1992年   32篇
  1991年   31篇
  1990年   27篇
  1989年   24篇
  1988年   28篇
  1987年   29篇
  1986年   25篇
  1985年   26篇
  1984年   34篇
  1983年   39篇
  1982年   35篇
  1981年   35篇
  1980年   41篇
  1979年   13篇
  1978年   17篇
  1977年   18篇
  1975年   14篇
  1973年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Chikungunya virus (CHIKV) vertical transmission occurs due to maternal viremia in the prepartum. Clinical presentation in neonates can be varied; however, the consequences of intrauterine exposure on the immune response are unclear. Thus, we aimed to analyze inflammatory alterations in children exposed to maternal CHIKV infection. This is a cross-sectional study that included children exposed to maternal CHIKV infection (confirmed by RT-qPCR and/or IgM). Circulant immune mediators were analyzed by a multiplex assay. RESULTS: We included 33 children, with a mean age of 3 ± 2.9 months-old, and 19 (57.6%) were male. Only one child presented neurological alterations. CHIKV-exposed infants showed elevated levels of MIP-1α, MIP-1β, and CCL-2 (p < 0.05). Pro-inflammatory cytokines such as TNFα, IL-6, and IL-7 (p < 0.0001) were also increased. In addition, lower levels of PDGF-BB and GM-CSF were observed in the same group (p < 0.0001). Principal component (PC) analysis highlighted a distinction in the inflammatory profile between groups, where PC explained 56.6% of the alterations. Our findings suggest that maternal exposure to CHIKV can affect the circulating levels of pro-inflammatory cytokines during the infants’ first year of life. The long-term clinical consequences of these findings should be investigated.  相似文献   
72.
Since 2006, the poultry population in Burkina Faso has been seriously hit by different waves of Highly Pathogenic Avian Influenza (HPAI) H5N1 epizootics. In December 2021, three distinct regions of Burkina Faso, namely, Gomboussougou, Bonyollo, and Koubri, detected HPAI H5N1 viruses in poultry. Whole genome characterization and statistical phylogenetic approaches were applied to shed light on the potential origin of these viruses and estimate the time of virus emergence. Our results revealed that the HPAI H5N1 viruses reported in the three affected regions of Burkina Faso cluster together within clade 2.3.4.4b, and are closely related to HPAI H5N1 viruses identified in Nigeria and Niger in the period 2021–2022, except for the PA gene, which clusters with H9N2 viruses of the zoonotic G1 lineage collected in West Africa between 2017 and 2020. These reassortant viruses possess several mutations that may be associated with an increased zoonotic potential. Although it is difficult to ascertain where and when the reassortment event occurred, the emergence of a H5N1/H9N2 reassortant virus in a vulnerable region, such as West Africa, raises concerns about its possible impact on animal and human health. These findings also highlight the risk that West Africa may become a new hotspot for the emergence of new genotypes of HPAI viruses.  相似文献   
73.
Duchenne muscular dystrophy (DMD) is a severe, progressive X-linked recessive disorder, caused by the absence of the dystrophin protein. A resolutive therapy for DMD is not yet available. The first approved drug for DMD patients with nonsense mutations is ataluren, approved for the treatment of children aged ≥ 2 yrs, that seems effective in slowing the disease progression. An earlier introduction of ataluren seems to give better results.We report the case of a 14-year-old DMD patient with a nonsense mutation in exon 70, still ambulant, who started taking ataluren at 12 years and remained stable for the following two years. The patient was on steroid since the age of 6, with beneficial effects. At two-years follow-up, an optimal disease evolution was observed, associated with a constant decrease of creatine kinase blood levels. Despite the late start of the treatment, ataluren seems to have significantly contributed to the stabilization of the functional status in this patient though it cannot be excluded that the result may have been influenced by the previous favorable course of the disease. However, further studies should be planned in patients with similar age treated with ataluren to better evaluate the treatment’s results compared to the natural course of the disease.Key words: Duchenne muscular dystrophy, target therapy, nonsense mutation, ataluren, time function tests  相似文献   
74.
75.
A randomized, multicenter, prospective study was conducted at 18 pancreas transplant centers in the United States to determine the role of induction therapy in simultaneous pancreas-kidney (SPK) transplantation. One hundred and 74 recipients were enrolled: 87 recipients each in the induction and noninduction treatment arms. Maintenance immunosuppression consisted of tacrolimus, mycophenolate mofetil, and corticosteroids. There were no statistically significant differences between treatment groups for patient, kidney, and pancreas graft survival at 1-year. The 1-year cumulative incidence of any treated biopsy-confirmed or presumptive rejection episodes (kidney or pancreas) in the induction and noninduction treatment arms was 24.6% and 31.2% (p = 0.28), respectively. The 1-year cumulative incidence of biopsy-confirmed, treated, acute kidney allograft rejection in the induction and noninduction treatment arms was 13.1% and 23.0% (p = 0.08), respectively. Biopsy-confirmed kidney allograft rejection occurred later post-transplant and appeared to be less severe among recipients that received induction therapy. The highest rate of Cytomegalovirus (CMV) viremia/syndrome was observed in the subgroup of recipients who received T-cell depleting antibody induction and received organs from CMV serologically positive donors. Decisions regarding the routine use of induction therapy in SPK transplantation must take into consideration its differential effects on risk of rejection and infection.  相似文献   
76.
Trazodone is approved for the treatment of major depressive disorders, marketed as immediate release (IR), prolonged release, and once a day (OAD) formulation. The different formulations allow different administration schedules and may be useful to facilitate patients’ compliance to the antidepressant treatment. A previously verified physiologically‐based pharmacokinetic model based on in vitro and in vivo information on trazodone pharmacokinetics was applied, aiming at predicting brain receptor occupancy (RO) after single and repeated dosing of the IR formulation and repeated dosing of the OAD formulation in healthy subjects. Receptors included in the simulations were selected using static calculations of RO based on the maximum unbound brain concentration (Cmax,brain,u) of trazodone for each formulation and dosing scheme, resulting in 16 receptors being simulated. Seven receptors were simulated for the IR low dose formulation (30 mg), with similar t onset and duration of coverage (range: 0.09–0.25 h and 2.1–>24 h, respectively) as well as RO (range: 0.64–0.92) predicted between day 1 and day 7 of dosing. The 16 receptors evaluated for the OAD formulation (300 mg) showed high RO (range: 0.97–0.84 for the receptors also covered by the IR formulation and 0.73–0.48 for the remaining) correlating with affinity and similar duration of time above the target threshold to the IR formulation (range: 2–>24 h). The dose‐dependent receptor coverage supports the multimodal activity of trazodone, which may further contribute to its fast antidepressant action and effectiveness in controlling different symptoms in depressed patients.

Study Highlights
  • WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?
The antidepressant efficacy of trazodone has been shown to be significantly correlated to its steady‐state plasma levels, and previous work has shown some understanding of trazodone range of affinity for different receptors, at different doses, but without considering the different available formulations. Trazodone is commonly available as: immediate release (IR), prolonged release (PR), and once a day (OAD) tablets. The IR formulation has a rapid onset and short duration of action, whereas the PR formulation is characterized by an absorption boost as soon as it is administered and has a comparatively delayed maximum concentration (Cmax). Conversely, the OAD formulation provides a controlled release of trazodone over 24 h without the early high peak plasma concentration seen with the IR and PR formulations.
  • WHAT QUESTION DID THIS STUDY ADDRESS?
This work aims to identify the brain receptors reaching a threshold occupancy of 50% through static predictions and determine the occupancy versus time profile for those of interest following administration of short‐ and long‐acting trazodone formulations.
  • WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?
Brain receptor occupancy (RO) for key targets were predicted based on free drug concentrations, allowing for a physiologically relevant assessment of the different pathways affected by each formulation and dose.
  • HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?
The presented physiologically‐based pharmacokinetic approach to assess RO can be used to guide formulation selection and dosing in clinical studies.  相似文献   
77.
Ophidian accidents caused by the subspecies Crotalus durissus are responsible for high morbity and mortality rates. Acute renal failure is a common complication observed in these accidents. The aim of the present study was to investigate the renal effects promoted by the venom of C. d. collilineatus and its fractions, crotoxin and phospholipase A2. C. d. collilineatus (Cdc; 30 microg mL(-1)), crotoxin (CTX; 10 microg mL(-1)) and phospholipase A2 (PLA2; 10 microg mL(-1)) were tested in isolated rat kidney. The first 30 min of each experiment were used as an internal control and Cdc or its fractions, CTX and PLA2 were added to the system after this period. All experiments lasted 120 min. The venom of Cdc decreased perfusion pressure (PP; control120 = 110.3 +/- 3.69 mmHg; Cdc120 = 96.7+/-8.1 mmHg), renal vascular resistance (RVR; control120 = 6.42+/-0.78 mmHg mL g(-1) min(-1); Cdc120 = 4.8+/-0.56 mmHg/mL g(-1) min(-1)), urinary flow (UF; control120 = 0.19+/-0.03 mL g(-1) min(-1); Cdc120 = 0.12 +/- 0.01 mL g(-1) min(-1)), and glomerular filtration rate (GFR; control120 = 0.79 +/- 0.07 mL g(-1) min(-1); Cdc120 = 0.53 +/- 0.09 mL g(-1) min(-1)), but had no effect on the percent of sodium tubular transport (%TNa+), percent of chloride tubular transport (%TK+) and percent of potassium tubular transport (%TCl-). CTX and PLA2 reduced the GFR, while UF, PP and RVR remained stable during the full 120 min of perfusion. Crotoxin administration also diminished the %TK+ (control120 = 69.94 +/- 6.49; CTX120 = 33.28 +/- 4.78) and %TCl- (control120 = 79.53 +/- 2.67; CTX120 = 64.62 +/- 6.93). PLA2 reduced the %TK+, but exerted no effect on the %TNa+ or on that of TCl-. In conclusion, the C. d. collilineatus venom altered the renal functional parameters evaluated. We suggest that crotoxin and phospholipase A2 were involved in this process, since the renal effects observed would be due to the synergistic action of the components of the venom.  相似文献   
78.
Sodium valproate is an anticonvulsant which elevates GABA levels in the brain. GABA interacts with dopamine functionally in certain areas of the brain involved in motor behavior such as the nucleus accumbens and the substantia nigra. In order to determine whether GABA can play a functional role in the pharmacological effects of valproate, both valproate and GABA were injected directly into these two brain areas and the effects of these compounds on motor function were studied. Both GABA and sodium valproate inhibited in a dose dependent manner the hyperactivity induced by the bilateral injection of dopamine into the nucleus accumbens. Picrotoxin, a GABA antagonist, blocked the inhibitory effect of valproate. When injected into the pars reticulata of the substantia nigra, both sodium valproate and GABA enhanced apomorphine-induced circling in rats with a unilateral lesion of lateral hypothalamus caused by 6-hydroxydopamine. This effect was blocked by the systemic administration of picrotoxin. These observations suggest that sodium valproate can produce effects that result from the activation of GABA receptor sites in the brain.  相似文献   
79.
80.
Chicken meat is becoming the most consumed in the world for both economic and nutritional reasons; regarding the latter, the lipid profile may play positive or negative roles in the prevention and treatment of diseases. In this study, we define the state of the art of lipid-based nutritional indexes and used the lipid content and fatty acid profile (both qualitative and quantitative) of breast meat of two poultry genotypes with different growth rates and meat traits. Further, we summarize and review the definitions, implications, and applications of nutritional indexes used in recent years and others of our own design to provide a useful tool to researchers working in the field of meat quality (not only in poultry) to select the most appropriate index for their own scientific purposes. All indexes show advantages and disadvantages; hence, a rational choice should be applied to consider the nutritional effect of meat on human health and for a possible assessment of the most suitable rearing systems (genotype, feeding, farming system or postmortem handling).  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