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   3960篇
  免费   186篇
  国内免费   83篇
耳鼻咽喉   110篇
儿科学   177篇
妇产科学   36篇
基础医学   492篇
口腔科学   83篇
临床医学   315篇
内科学   987篇
皮肤病学   57篇
神经病学   240篇
特种医学   383篇
外国民族医学   4篇
外科学   459篇
综合类   37篇
预防医学   227篇
眼科学   38篇
药学   327篇
中国医学   7篇
肿瘤学   250篇
  2023年   23篇
  2022年   31篇
  2021年   66篇
  2020年   42篇
  2019年   56篇
  2018年   70篇
  2017年   57篇
  2016年   53篇
  2015年   77篇
  2014年   78篇
  2013年   99篇
  2012年   166篇
  2011年   170篇
  2010年   117篇
  2009年   114篇
  2008年   173篇
  2007年   226篇
  2006年   142篇
  2005年   149篇
  2004年   129篇
  2003年   117篇
  2002年   119篇
  2001年   119篇
  2000年   95篇
  1999年   105篇
  1998年   92篇
  1997年   99篇
  1996年   74篇
  1995年   89篇
  1994年   58篇
  1993年   54篇
  1992年   72篇
  1991年   69篇
  1990年   65篇
  1989年   88篇
  1988年   84篇
  1987年   75篇
  1986年   66篇
  1985年   72篇
  1984年   41篇
  1983年   37篇
  1982年   38篇
  1981年   35篇
  1980年   38篇
  1979年   40篇
  1978年   19篇
  1977年   27篇
  1976年   29篇
  1975年   26篇
  1974年   21篇
排序方式: 共有4229条查询结果,搜索用时 15 毫秒
101.
The aim of this study is to analyse the results of revision surgery for failed adult spinal deformity patients and to describe the surgical strategy selection process, based on the identification of the main clinical diagnosis responsible for failure. We retrospectively reviewed the clinical and radiological data of 77 consecutive patients treated in a 3-year time (2016–2019) for surgical revision of long fusion (more than five levels fused) for adult spinal deformity in a high-volume spine centre, divided into four groups based on the diagnosis: rod breakage (RB) group, proximal junctional failure (PJF) group, distal junctional failure (DJF) group and loss of correction (LOC) group with symptomatic sagittal or coronal malalignment (including iatrogenic flatback). Seventy-seven patients met our inclusion criteria, with a female prevalence (66 F vs. 11 M). The mean age at revision surgery was 63. Fused levels before surgery were averagely 12, and revision added averagely two levels to the preexisting fusion area. Clinical status was apparently improved in ODI scores and VAS scores, while it was slightly worsened in SF36 scores. Different diagnosis groups have been addressed with different surgical strategies, according to the different surgical goals: interbody cages and multi-rod construct to improve stiffness and favour bony fusion, “kickstand” rod and “tie” rod to correct coronal and sagittal malalignment, specific rod contouring and proximal hooks in “claw” configuration to reduce mechanical stress at the proximal junctional area. Intraoperative complications occurred in 18% of patients and perioperative complications in 39%. Revision surgery in long fusions for adult spinal deformity is a challenging field. Surgical strategy should always be planned carefully. A successful treatment is a direct consequence of a correct preoperative diagnosis, and surgery should address the primary cause of failure. All the above-mentioned surgical techniques and clinical skills should be part of surgeon’s expertise when managing these patients. These slides can be retrieved under Electronic Supplementary Material.  相似文献   
102.
Subcutaneous triptan provides immediate analgesia in migraine and cluster headache but is limited by high pain recurrence due to rapid drug elimination. A dual-acting subcutaneous formulation providing immediate release of a triptan and slow but sustained release of a nonsteroidal anti-inflammatory drug may provide a longer duration of relief. A microemulsion-based technology has various advantages over other technically complex dosage forms. Oil-in-water microemulsions of zolmitriptan and diclofenac acid using Labrafac Lipophile, Tween 80, Capryol 90 and water were prepared. One formulation was characterised in vitro and found to have uniformly dispersed nanosized globules. The formulation provided differential release of zolmitriptan and diclofenac acid both in vitro as well as in vivo that may be potentially beneficial to migraine patients.  相似文献   
103.
JB Ma  SX Yao  H  Li  Q  Pei JF  Yao 《美中国际创伤杂志》2014,(1):1-4,9
In this case, a male patient presented with a clinically and radiographieally unstable slipped capital femoral epiphysis (SCFE) as well as slipped calcaneal epiphysis years. Subsequent thorough at the age of 23 work-up revealed that he had some features of rickets and labo- ratory test demonstrated he had hypophos- phatemia (2.3mg/dl), normocalcemia, normal vi- tamin D metabolite levels, and secondary hy- perparathyroidism.  相似文献   
104.
105.
There is increasing evidence that genetic factors have a role in differential susceptibility to depression in response to severe or chronic adversity. Studies in animals suggest that nitric oxide (NO) signalling has a key role in depression-like behavioural responses to stress. This study investigated whether genetic variation in the brain-expressed nitric oxide synthase gene NOS1 modifies the relationship between psychosocial stress and current depression score. We recruited a population sample of 1222 individuals who provided DNA and questionnaire data on symptoms and stress. Scores on the List of Life-Threatening Experiences (LTE) questionnaire for the last year and self-rated current financial hardship were used as measures of recent/ongoing psychosocial stress. Twenty SNPs were genotyped. Significant associations between eight NOS1 SNPs, comprising two regional haplotypes, and current depression score were identified that survived correction for multiple testing when current financial hardship was used as the interaction term. A smaller three-SNP haplotypes (rs10507279, rs1004356 and rs3782218) located in a regulatory region of NOS1 showed one of the strongest effects, with the A-C-T haplotype associating with higher depression scores at low adversity levels but lower depression scores at higher adversity levels (p=2.3E-05). These results suggest that NOS1 SNPs interact with exposure to economic and psychosocial stressors to alter individual''s susceptibility to depression.  相似文献   
106.

Background  

Leishmaniases are among the most proteiform parasitic infections in humans ranging from unapparent to cutaneous, mucocutaneous or visceral diseases. The various clinical issues depend on complex and still poorly understood mechanisms where both host and parasite factors are interacting. Among the candidate factors of parasite virulence are the A2 genes, a family of multiple genes that are developmentally expressed in species of the Leishmania donovani group responsible for visceral diseases (VL). By contrast, in L. major determining cutaneous infections (CL) we showed that A2 genes are present in a truncated form only. Furthermore, the A2 genomic sequences of L. major were considered subsequently to represent non-expressed pseudogenes [1]. Consequently, it was suggested that the structural and functional properties of A2 genes could play a role in the differential tropism of CL and VL leishmanias. On this basis, it was of importance to determine whether the observed structural/functional particularities of the L. major A2 genes were shared by other CL Leishmania, therefore representing a proper characteristic of CL A2 genes as opposed to those of VL isolates.  相似文献   
107.
A human malignant melanoma cell line (M3Dau) was observed by electron microscopy to interact directly with human platelets and induced platelet aggregation. Fab fragments of a monoclonal antibody MoAb (LYP18), directed against the platelet glycoprotein (GP) IIb-IIIa complex, inhibited platelet-melanoma interactions and platelet-platelet aggregation. M3Dau melanoma cells bind LYP 18 and synthesize IIb-IIIa- like GPs. When the melanoma cells were preincubated with LYP 18, tumor- platelet interaction did not occur, suggesting that the interaction may be mediated by the IIb-IIIa-like GPs present on the melanoma cell surface. Glanzmann's thrombasthenic platelets, lacking GPIIb and IIIa, did not interact with melanoma cells, indicating that the platelet GPIIb-IIIa complex is also necessary for the platelet-melanoma cell interaction. This work demonstrates the importance of the IIb-IIIa-like GPs, present on M3Dau melanoma cells, in mediating tumor-platelet interactions.  相似文献   
108.
Most studies of plasma beta-endorphin concentrations in pregnant women show that these are highly elevated. This might indicate a role for opiate peptides during pregnancy and in the fetus-mother relationship. We measured plasma beta-endorphin, beta-lipotropin, and met-enkephalin concentrations in normal and drug-addicted women during pregnancy, labor, and delivery, and in their newborn infants. Peptides were measured by RIA after extraction and concentration on silica columns and separation by high pressure liquid chromatography. In both normal and drug-addicted mothers we found an increase in plasma beta-endorphin during pregnancy, without a concomitant increase in plasma beta-lipotropin or metenkephalin. Only beta-lipotropin increased dramatically in both groups at delivery, whereas beta-endorphin and met-enkephalin remained unchanged. Peptide concentrations in umbilical plasma were similar to those in peripheral plasma of the mothers. On day 1 of life plasma beta-endorphin, beta-lipotropin, and met-enkephalin concentrations in the newborn from normal mothers were higher than in nonpregnant adult subjects and gradually decreased toward normal adult values by day 5 of life. Plasma beta-endorphin, beta-lipotropin, and met-enkephalin concentrations of newborn infants of drug-addicted mothers increased dramatically on day 2 and 3 of life, up to 1000-fold the concentrations of normal adults, and remained elevated up to 40 days after birth. In conclusion, beta-endorphin, beta-lipotropin, and met-enkephalin concentrations during pregnancy are not affected by drug addiction, whereas in the newborn of drug addicted mothers concentrations of these compounds are markedly increased.  相似文献   
109.
The functional capacities of granulocytes in patients with chronic granulocytic leukemia are still a subject of controversy, probably due to the heterogeneity of the abnormalities observed from patient to patient. For a better definition of these abnormalities, 14 patients with untreated chronic granulocytic leukemia were studied. The patients were divided into three groups on the basis of the functional activities of their phagocytosing granulocytes. In four patients (group I), the granulocytes were normal in respect to particle ingestion, nitroblue tetrazolium (NBT)-stimulated reduction, cyanide-insensitive oxygen (O2) consumption, superoxide anion (O2-)-stimulated production, hydrogen peroxide (H2O2) production, and iodination. They also had a normal myeloperoxidase (MPO) content. In four patients (group III), the granulocytes were significantly defective in all of these activities. In the six remaining patients (group II), all the initial metabolic steps of the phagocytosing granulocytes (ingestion, NBT reduction, O2 consumption, O2-production, H2O2 production) were normal, as were the MPO content of the granulocytes, while iodination was strikingly decreased. These metabolic features suggested a degranulation defect which was observed ultrastructurally in the only patient studied among these six. The phagocytosing granulocytes of this patient did not degranulate and no deposits of MPO activity were seen in the phagosomes.  相似文献   
110.
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