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   2331篇
  免费   94篇
  国内免费   33篇
耳鼻咽喉   111篇
儿科学   88篇
妇产科学   134篇
基础医学   204篇
口腔科学   83篇
临床医学   181篇
内科学   535篇
皮肤病学   19篇
神经病学   168篇
特种医学   125篇
外科学   524篇
综合类   32篇
预防医学   46篇
眼科学   97篇
药学   65篇
中国医学   8篇
肿瘤学   38篇
  2024年   4篇
  2023年   15篇
  2022年   25篇
  2021年   44篇
  2020年   32篇
  2019年   28篇
  2018年   62篇
  2017年   45篇
  2016年   81篇
  2015年   95篇
  2014年   97篇
  2013年   132篇
  2012年   153篇
  2011年   150篇
  2010年   112篇
  2009年   75篇
  2008年   202篇
  2007年   193篇
  2006年   190篇
  2005年   195篇
  2004年   154篇
  2003年   158篇
  2002年   100篇
  2001年   12篇
  2000年   11篇
  1999年   6篇
  1998年   10篇
  1997年   14篇
  1996年   11篇
  1995年   5篇
  1994年   4篇
  1993年   4篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1986年   3篇
  1985年   2篇
  1984年   2篇
  1979年   2篇
  1977年   2篇
  1976年   2篇
  1974年   3篇
  1971年   2篇
  1970年   1篇
  1968年   1篇
  1966年   1篇
  1939年   1篇
  1937年   1篇
  1936年   2篇
  1928年   1篇
排序方式: 共有2458条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: We aimed to determine whether serum concentrations of anti-Müllerian hormone (AMH) can be used as a tool for prediction of the efficacy of sperm retrieval. METHODS: This was a prospective cohort observational study. AMH levels were determined in 47 men presenting for infertility evaluation. Group 1 consisted of 24 infertile patients diagnosed with non-obstructive azoospermia. Group 1 was further divided into two subgroups. The patients with spermatozoa in their testicular samples constituted group 1a (n = 13), while the patients with absence of spermatozoa constituted group 1b (n = 11). Twenty-three normozoospermic fertile men constituted group 2. Serum AMH was measured before obtaining testicular specimens. RESULTS: Testicular spermatozoa were recovered in 13 out of the 24 patients (54%). Demographic characteristics of the three groups were similar. The difference between serum AMH levels among the three groups did not reach statistical significance. CONCLUSIONS: We speculated that although AMH is secreted predominantly into the seminiferous tubules, studying serum samples might be more advantageous than seminal plasma because the presence of seminal proteases could influence AMH levels in the latter. However, our results did not demonstrate differences in serum concentrations of AMH between the studied groups. Studies with extended patient populations focusing on seminal plasma concentrations of AMH are warranted.  相似文献   
2.
Environmental fungi, in particular primary pathogens and Cryptococcus spp. can be responsible for skin lesions mimicking sporotrichosis. In this paper, we report a case of subcutaneous cryptococcosis in an apparently healthy, young male patient due to a non-C. neoformans Cryptococcus species, C. diffluens. The isolate showed in vitro phenotypic switching that may affect virulence and host inflammatory and immune responses, and in vitro resistance to amphotericin B and 5-flucytosin. This species shares several phenotypic traits with C. neoformans, and, therefore, decisive diagnosis should be based on biopsy and culturing results followed by molecular identification.  相似文献   
3.
Summary The effects of combined renovascular hypertension and diabetes mellitus on the rat heart were investigated in order to detect possible synergistic effects of the two conditions. Hypertensive diabetic and hypertensive non-diabetic animals were compared to diabetic and non-diabetic controls. Hypertension was established for 12 weeks by a surgical stenosis of the left renal artery; diabetes mellitus was maintained for 8 weeks by a single intraperitoneal injection of 60 mg/kg streptozotocin. Light microscopic stereology did not reveal significant divergences between diabetic hypertensives and non-diabetic hypertensives. Hypertension induced a focal perivascular and interstitial fibrosis with increased volume densities of non-vascular interstitium and fibrosis (P<0.001). Capillary density (QA) was decreased in transverse sections (P<0.01) and increased in longitudinal sections (P<0.01). This indicates a three-dimensional remodelling of the capillary bed with an increased number of obliquely running capillaries. At least the length density (LV) of capillaries (mm/mm3) tends to be normalized in long-term renovascular hypertension. At the ultrastructural level, a synergism of hypertension and diabetes mellitus was observed: the volume ratio of mitochondria to myofibrils was significantly decreased in hypertensive diabetics, but not in non-diabetic hypertensives or in diabetics. This may enhance the risk of cardiac deterioration. We conclude that the primary target of the synergistic damage in hypertensive diabetic heart muscle disease is the myocardial cell and not the cardiac interstitium.Preliminary results of this study have been published in: Mall G (1991) Morphometric study on the rat heart in combined renovascular hypertension and diabetes mellitus. In: Nagano N, Dhalla NS (eds) The diabetic heart. Raven Press, New York, pp 115–124Dedicated to Prof. Dr. med. G. Seifert on the occasion of his 70th birthday  相似文献   
4.
As visual guidance of facial movements is impossible, accurate movements for speech and mastication require an established body image that is formed via the information from mechanoreceptors in the skin, mucosa, periodontium, and proprioceptors in the facial and masticatory muscles and in the jaw joints. In this study we aimed to investigate how the acute deafferentation of lips and teeth alters the established image of lips, teeth and the thumb. We used a psychophysical method to determine whether the perceived sizes of the upper lip and front teeth change when the sensory input from the lips and front teeth is fully blocked. We also examined the perceived size of the thumb to test for acute interactions between the thumb and facial structures. Local anaesthetic blocking of upper lip and upper front teeth significantly increased the perceived size of the upper lip by as much as 100% (range 21–100%) in ten out of eleven subjects tested (overall mean 52%; p=0.001). The perceived size of the upper teeth also significantly increased by as much as 155% (range 30–155%) in eight of the eleven subjects during anaesthesia (overall mean 41%; p=0.035). When the region of anaesthesia was increased and both upper and lower teeth and lips were anaesthetised, the perceived size of the upper lip again increased, by 53% (p=0.040), but the change in perceived size of the upper front teeth (18%) was not significant (p=0.206). In both studies there was no change in perceived size of the thumb. The results illustrate the labile central interaction between sensory inputs and the importance of feedback from peripheral afferents in generating the subjective facial image. The timing, level, and area of anaesthesia may be important modifiers of these interactions.  相似文献   
5.
In the present study, attempts have been made to determine the effects of honey on intestinal morphology, postoperative adhesions, and the healing of colonic anastomoses in the rats after colonic resection and anastomosis. Thirty-six rats were randomly divided into three groups each including 12 animals. Colonic resection and anastomosis were performed on all animals. Rats were fed with standard rat chow in group I, standard rat chow plus 10 g/kg/day honey in group II and artificial honey including the same caloric amount with honey in group III. Adhesion scores, bursting pressures and histopathological examinations were evaluated. Colonic bursting pressures of honey group were significantly better than control and artificial honey groups. Histological analysis of anastomotic site showed that submucosa and muscularis propria were nearly filled with granulation tissue and regular fibrin matrix in honey group. There was statistically significant difference between the adhesion scores of honey vs artificial honey and control groups. The scores of histological changes of ileum in honey group were significantly different from other groups. These results indicate a protective role of honey against intraabdominal adhesions and anastomotic dehiscence.  相似文献   
6.
7.
8.
BACKGROUND: Different ovulation trigger methods such as gonadotropin releasing hormone-agonist (GnRH-a) and recombinant human chorionic gonadotropin (r-hCG) plus rescue oocyte retrieval might reveal oocytes in patients with recurrent empty follicle syndrome. CASE: Endogenous luteinizing hormone was triggered with a GnRH-a (Buserelin [Suprefact pro-injection, Aventis-Pharma, Turkey], 250 microg subcutaneously) in a GnRH antagonist (Cetrorelix [Cetrotide 0.25, SeronoTurkey], 0.25 mg/d, starting on day 6), down-regulated cycle. At the first scheduled retrieval, 3 cumulus-oocytecorona complexes were recovered from the left ovary. During chemical denudation with hyaluronidase, 2 of them underwent lysis. The third was a zona-free, germinalvesicle-stage oocyte after mechanical denudation. Oocyte pickup was stopped, and recombinant human chorionic gonadotropin (hCG) (250 microg subcutaneously) was injected. Five cumulus-oocyte-corona complexes were retrieved from the right ovary 24 hours after rescue with recombinant hCG. Only mechanical denudation was done, and 4 zona-free oocytes with germinal vesicle breakdown were seen. All oocytes underwent intracytoplasmic sperm injection, and none of them were fertilized. CONCLUSION: Oocyte maturation defects should be included in etiologic mechanisms for counseling patients with empty follicle syndrome.  相似文献   
9.
BACKGROUND: We investigated the effect of alpha-lipoic acid (LA) on reperfusion injury in a rat ovarian torsion-detorsion model. The changes in tissue and plasma levels of malondialdehyde (MDA), end-product of lipid peroxidation, superoxide dismutase (SOD), xanthine oxidase (XO) and nitric oxide (NO), were determined. Ovarian histopathological findings were scored and compared among groups. MATERIALS AND METHODS: Thirty-two female Sprague-Dawley rats were divided into four groups. Sham operation was performed in group I; in group II only ovarian torsion was performed. Group III received intraperitoneal injections of saline, and group IV received LA via intraperitoneal injections (LA group: aqueous solution at 36 mg/kg of body weight per day, saline group: equal volume of saline) 21, nine, and one hour before torsion of the ovary. Rats in the torsion group were killed after 360 degrees clockwise adnexial torsion for three hours, and ovaries were harvested. After three hours of adnexial detorsion, the rats in saline group and LA group were killed and adnexa were surgically removed. RESULTS: Ovarian tissue damage scores were significantly different among groups and were seen to correlate with tissue MDA levels. Ovarian tissue and serum MDA, NO and serum XO levels in the group III were significantly higher than those of the groups I and IV (P<0.05). The serum levels of SOD in the group III were significantly lower than those of the groups I and IV (P<0.05). CONCLUSION: These results suggest that LA pretreatment has beneficial effects in the prevention of ischaemia-reperfusion injury of the ovaries.  相似文献   
10.
The novel coronavirus-19 (COVID-19) pandemic has considerably impacted children’s lives. The aim of this study was to determine whether the pandemic affected mealtime regularity among preschool children and whether maintaining regular mealtimes or changes in mealtime regularity during the pandemic were related to dietary balance, including chronological relationships. This online cross-sectional survey involving individuals registered with a company that provides meals to children aged 2−6 years was conducted in February 2021. Using a 40-point scale, a healthy diet score (HDS) was developed to evaluate children’s dietary balance. The participants were divided into four groups based on their responses, and multiple regression analyses were performed with the HDS as the dependent variable. Maintaining regular mealtimes was associated with practices such as waking and going to bed earlier, less snacking, and eating breakfast every day. Even after adjusting for basic attributes, lifestyle habits, household circumstances, and other factors, regular mealtimes were still positively correlated with the HDS. These findings indicate that maintaining regular mealtimes is associated with higher HDS scores and better lifestyle habits. Furthermore, as the changed HDS was higher in the group whose mealtimes became regular during the pandemic, adopting regular mealtimes may lead to a more balanced diet.  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