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   1125篇
  免费   38篇
  国内免费   3篇
耳鼻咽喉   3篇
儿科学   55篇
妇产科学   16篇
基础医学   130篇
口腔科学   12篇
临床医学   75篇
内科学   196篇
皮肤病学   49篇
神经病学   66篇
特种医学   15篇
外科学   121篇
综合类   57篇
一般理论   1篇
预防医学   63篇
眼科学   92篇
药学   140篇
中国医学   8篇
肿瘤学   67篇
  2023年   8篇
  2022年   47篇
  2021年   74篇
  2020年   49篇
  2019年   45篇
  2018年   45篇
  2017年   27篇
  2016年   42篇
  2015年   40篇
  2014年   53篇
  2013年   71篇
  2012年   88篇
  2011年   78篇
  2010年   51篇
  2009年   41篇
  2008年   54篇
  2007年   39篇
  2006年   29篇
  2005年   32篇
  2004年   16篇
  2003年   19篇
  2002年   24篇
  2001年   23篇
  2000年   22篇
  1999年   14篇
  1998年   4篇
  1997年   2篇
  1996年   2篇
  1994年   2篇
  1993年   3篇
  1992年   15篇
  1991年   15篇
  1990年   14篇
  1989年   6篇
  1988年   11篇
  1987年   3篇
  1986年   3篇
  1985年   5篇
  1984年   4篇
  1982年   2篇
  1980年   4篇
  1979年   3篇
  1978年   3篇
  1977年   6篇
  1976年   5篇
  1975年   4篇
  1972年   3篇
  1966年   5篇
  1965年   3篇
  1932年   1篇
排序方式: 共有1166条查询结果,搜索用时 15 毫秒
51.
Objective To determine the frequency of cervical pathology and the incidence of cervical neoplasia in women presenting with PCB at the colposcopy clinic with negative cytology. Design A retrospective study. Setting A district general hospital. Population Eighty-seven women with postcoital bleeding and negative cytology were seen in the colposcopy unit during 1 January 2003 to 31 December 2005. Methods Women were identified from computer records and details were extracted from the case notes. Main outcome measure Histopathological diagnosis. Results Six women (6.9%) had cervical intraepithelial neoplasia. There were no cases of invasive cancer. Thus in our study 6.9% women with postcoital bleeding had abnormal histology even though they had normal smears. Other identifiable causes were cervical polyp (12.5%), ectopy (33.6%) and Chlamydia (2.3%). No pathology was found in 50% of women. Conclusion Women with postcoital bleeding even with normal smears appear to be at much greater risk of cervical neoplasia than the general population. Unfortunately there is no general consensus for management of these patients. Hence further research is needed to standardise the management of women with PCB. Patients should be reassured that in vast majority of cases no serious pathology is detected.  相似文献   
52.
AIM: Management of post cesarean pregnancy continues to be a dilemma. The present study was undertaken to evaluate the outcome of such pregnancies in a resource constrained setting so that an appropriate management protocol can be decided. METHODS: An observational study was conducted in the Department Of Obstetrics And Gynecology, King George's Medical University, Lucknow, India. The outcome of all of the women admitted with pregnancy with a previous cesarean section was noted. RESULTS: A total number of 447 women with a post cesarean pregnancy underwent delivery. These comprised 13.7% of total deliveries over the same period. 124 women (27.7%) had successful vaginal delivery while 323 (72.3%) had a repeat cesarean section. Maternal morbidity and perinatal mortality were both significantly higher in the vaginal delivery group (P = 0.00211 and P = 0.0426, respectively). CONCLUSIONS: Vaginal birth after cesarean (VBAC) is associated with higher maternal morbidity and perinatal mortality. Therefore the decision for VBAC must be taken only after proper consideration and counseling of the couple.  相似文献   
53.
Introduction  The study was carried out to quantify the changes induced by the pandemic in plastic surgery practice and training and to study the impact of the webinars on plastic surgery education from a residents’ perspective. Methods  In this multicentric study, the number and type of surgeries, cause of injuries, and their regional variation during the coronavirus disease 2019 (COVID-19) period (February–September 2020) were compared with pre–COVID-19 time. An online survey on the impact of webinars was conducted for plastic surgery trainees across the country. Results  There was a significant reduction in total number of surgeries ( p = 0.003). The procedures for hand ( p = 0.156), faciomaxillary injuries ( p = 0.25), and replantations ( p = 0.46) were comparable; there was a significant reduction in combined orthopedic-plastic-surgical procedures ( p = 0.009) during the pandemic. There was a significant reduction in road accidents ( p = 0.007) and suicidal injuries ( p = 0.002) and increase in assault ( p = 0.03) and domestic accidents ( p = 0.01) during the COVID-19 period. A usefulness score of >8 was given for the webinars by 68.7% residents. There was no significant difference in perception of utility when correlated with the academic program at their institutes ( p = 0.109); 92% opined webinars should continue in post-COVID times. Conclusion  There was a drastic reduction in number of elective and emergency procedures during the COVID-19 time, negatively affecting resident training program. Majority of residents felt that webinars could prove a useful adjunct to training in formal training program in post-COVID-19 scenario.  相似文献   
54.
Tetrazoles are indispensable nitrogen containing heterocyclic scaffolds that offer a broad spectrum of applications in various domains such as medicinal chemistry, high energy material science, biochemistry, pharmacology etc. Owing to their useful applications, a wide range of catalysts have been explored for green synthesis of tetrazole derivatives. In recent times, nanomaterials have been emerged as extremely efficient catalysts for different organic transformations because of their high surface area-to-volume ratio, easy surface modification, simple fabrications, easy recovery and reusability. In this article, we have presented an overview of utilization of various nano-catalysts, nanocomposites and other solid-supported nanomaterials as an efficient environmental benign catalytic system for green synthesis of tetrazoles and derivatives. This review will provide an exclusive emphasis on boehmite, magnetic, copper, carbon, MCM-41, and composite based nanomaterials that have been developed since the year 2010 for the synthesis of tetrazole derivatives. In addition, we have briefly discussed the fabrication, functionalization and characterization of some novel nanomaterials and their advantages in the synthesis of tetrazole and its derivatives along with the reaction mechanism that involves synthesis of tetrazole derivatives via nanomaterials catalysed reactions.

Tetrazoles are indispensable nitrogen containing heterocyclic scaffolds that offer a broad spectrum of applications in various domains such as medicinal chemistry, high energy material science, biochemistry, pharmacology etc.  相似文献   
55.
56.
The present study was undertaken to isolate a novel antidiabetic molecule from Swietenia macrophylla seeds. The hydroalcohol extract of Swietenia macrophylla seeds was subjected for bioassay guided isolation employing glucose utilization assay by the isolated rat hemi‐diaphragm method in vitro. One tetranortriterpenoid, swietenine, isolated from the chloroform fraction exhibited significant (p < 0.01) activity and the effect was comparable to that of human insulin (p < 0.01). Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
57.
The present study describes the in vivo effects of anti-leprosy drugs on rat peritoneal macrophages and T-cell homeostasis. It was observed that BCG-elicited rat peritoneal macrophages produced more H2O2 and expressed more Ia antigen on their cell surfaces compared with resident peritoneal macrophages. Furthermore, elicited macrophages isolated from rats administered multidrug therapy (MDT), consisting of dapsone, clofazimine and rifampicin in high dose (10 x MDT) released more O2-. On the contrary, there was a significant decrease in the Ia antigen expression on these macrophages. Anti-leprosy drug treatment in high dose (10 x MDT) decreased the total number of blood T-helper (W3/25+) cells and increased the total number of blood T-suppressor (OX-8+) cells which resulted in a significant decrease in a W3/25: OX-8 ratio. Electron microscopy of elicited macrophages isolated from 10 x MDT treated rats showed development of many filipodia compared with control macrophages. These data show that 10 x MDT treatment in rats for 1 month alters the homeostasis of blood T-cell subpopulations which perhaps decreases the Ia expression on macrophages. However, the increase in O2- production and the appearance of filipodia on the macrophages is due to a direct effect of drugs on the macrophages. MDT treatment for 1 month in a therapeutic dose has no effect on the above-mentioned parameters.  相似文献   
58.
Microbial co-infections are another primary concern in patients with coronavirus disease 2019 (COVID-19), yet it is an untouched area among researchers. Preliminary data and systematic reviews only show the type of pathogens responsible for that, but its pathophysiology is still unknown. Studies show that these microbial co-infections are hospital-acquired/nosocomial infections, and patients admitted to intensive care units with invasive mechanical ventilation are highly susceptible to it. Patients with COVID-19 had elevated inflammatory cytokines and a weakened cell-mediated immune response, with lower CD4+ T and CD8+ T cell counts, indicating vulnerability to various co-infections. Despite this, there are only a few studies that recommend the management of co-infections.  相似文献   
59.
Purpose In women the relationship between myotonic dystrophy type I and fertility remains controversial. The objective of this study was to evaluate the ovarian reserve, ovarian response to stimulation and oocyte quality in these patients. Materials and methods We compared 15 myotonic dystrophy type I patients with 39 age matched controls with isolated male factor infertility necessitating ICSI. Results All parameters of ovarian reserve (day 3 FSH and E2, antral follicle count and delta E2) were significantly better in the controls. Despite having significantly lower doses of gonadotrophin, the control group attained a higher number of retrieved oocyte–cumulus complexes (p < 0.04). Analysis of cytoplasmic and extracytoplasmic dysmorphism did not reveal any difference between the two groups. Fertilisation rate and top grade embryos on day 3 were similar in both groups. Conclusion The present study suggests that though women with myotonic dystrophy type I have a reduced ovarian reserve and respond poorly to controlled ovarian stimulation, there is no impact on oocyte and embryo quality. Hence suggesting that successful ART is feasible with appropriate selection in women with mild myotonic dystrophy. Capsule Women with myotonic dystrophy type I have reduced ovarian reserve and respond poorly to controlled ovarian stimulation, though there is no impact on oocyte quality.  相似文献   
60.
India is endemic for foot-and-mouth disease (FMD) and in recent years a unique group within serotype A, carrying a codon deletion at an antigenically critical site in capsid protein VP3 has emerged (VP359-deletion group). This tempted us to analyze the noncoding region, which is an under represented area, though critically associated with virus biology and pathogenesis. Analysis of the large fragment of 5′ untranslated region (LF-5′ UTR) of type A FMD virus revealed discrepancy in the overall tree topology between LF-5′ UTR and 1D region possibly due to independent evolution of coding and noncoding regions. The VP359-deletion group maintained its phylogenetic distinctness even at the LF-5′ UTR. Eighteen lineage specific signatures detected here support independent evolutionary paths for the lineages. Extensive deletions of 45 and 89 nucleotides corresponding to the pseudoknot region were noticed. Conservation pattern in the ‘A253AACA’ motif in the cre/bus stem-loop indicates the importance of first three ‘A’ residues in VPg uridylylation. Of the three polypyrimidine tract binding protein (PTB) binding sites mapped on the internal ribosome entry site (IRES), the pyrimidine tract (Py tract) in the loop of domain 2 was found to be maximally conserved and it might be the major PTB binding site. Strikingly, a deletion group lineage specific transversion was noticed in the Py tract at the 3′ end of IRES without significantly affecting its in vitro infectious titer. Hence, we presume that for efficient cap-independent viral translation, either a minimum number of pyrimidine residues rather than a complete Py tract or a Py tract tolerating transversions only at specific locations and a core motif ‘CUUU’ within the Py tract is essential.  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