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   2031篇
  免费   105篇
  国内免费   11篇
耳鼻咽喉   10篇
儿科学   93篇
妇产科学   36篇
基础医学   304篇
口腔科学   73篇
临床医学   119篇
内科学   331篇
皮肤病学   39篇
神经病学   144篇
特种医学   34篇
外科学   225篇
综合类   44篇
一般理论   1篇
预防医学   194篇
眼科学   106篇
药学   214篇
中国医学   14篇
肿瘤学   166篇
  2023年   18篇
  2022年   38篇
  2021年   66篇
  2020年   33篇
  2019年   56篇
  2018年   63篇
  2017年   44篇
  2016年   56篇
  2015年   53篇
  2014年   82篇
  2013年   110篇
  2012年   142篇
  2011年   145篇
  2010年   99篇
  2009年   90篇
  2008年   122篇
  2007年   107篇
  2006年   108篇
  2005年   104篇
  2004年   76篇
  2003年   91篇
  2002年   72篇
  2001年   59篇
  2000年   36篇
  1999年   48篇
  1998年   23篇
  1997年   12篇
  1996年   8篇
  1995年   12篇
  1994年   9篇
  1993年   10篇
  1992年   21篇
  1991年   15篇
  1990年   12篇
  1989年   10篇
  1988年   15篇
  1987年   12篇
  1986年   12篇
  1985年   11篇
  1984年   13篇
  1983年   3篇
  1982年   3篇
  1981年   3篇
  1977年   2篇
  1975年   2篇
  1974年   2篇
  1973年   4篇
  1970年   3篇
  1965年   2篇
  1964年   2篇
排序方式: 共有2147条查询结果,搜索用时 0 毫秒
91.
Spontaneous abortion is the loss of pregnancy during an early gestational period. Interleukin-10 is an anti-inflammatory cytokine which plays an important role in successful pregnancy outcome. The aim of the study is to elucidate an association of IL-10 gene promoter polymorphisms (-1082G/A, -819 C/T, -592C/A) in spontaneous abortions from Telangana state of South India. The present population-based retrospective case-control triad study includes a total of 80 case families with spontaneous abortions and 100 control families with medically terminated pregnancies. Peripheral blood from all the couples and fetal tissues of <20 weeks of gestation were collected. Genotype analysis was carried out by a standard amplification refractory mutation system–polymerase chain reaction followed by agarose gel electrophoresis. The strength of the association between IL-10 gene promoter polymorphisms and spontaneous abortions were measured by odd ratios and their respective 95% confidence intervals. Haplotype analysis was carried out for the three polymorphisms to establish an association of specific haplotypes with spontaneous abortions. The increased frequency of AA genotype and A allele of -1082G/A, TT genotype and T allele of -819C/T, and AA genotype and A allele of -592C/A was observed in case fetuses and case mothers compared to their respective controls. Haplotype analysis revealed that A-C-A, G-C-A haplotypes in fetuses and haplotypes A-C-C, G-T-C, A-T-A, and G-C-A in mothers were associated with increased risk of spontaneous abortions. IL-10 gene promoter polymorphisms may act as a major genetic regulator in the etiology of spontaneous abortions with maternal genome imprinting effects.  相似文献   
92.
Food allergies have increased significantly in the past decade. An accurate history is crucial in approaching the management. At the outset, food intolerance must be distinguished from food allergies and, furthermore, these allergies should be classified into either an IgE, Non-IgE, or a mixed response. The clinical features vary from life-threatening anaphylaxis to milder IgE-mediated responses, atopic dermatitis, and gastrointestinal symptoms. The severity of the reaction and the potential risk for anaphylaxis on reexposure should be assessed. Milk, soy, egg, wheat, and peanut allergies are common in children, whereas peanut, tree nut, fish, shell fish allergies, and allergies to fruits and vegetables are common in adults. Structural proteins are important determinants of the severity of the reactions and may often predict the natural history and cross reactivity. Diagnostic work up must be guided by the clinical history. Skin testing and food-specific IgE done by standard methods are very useful, whereas oral challenges may be indicated in some situations. Majority of the patients outgrow their allergies to milk, soy, egg, and wheat, and some to peanut also, therefore, patients should be periodically reassessed. Novel diagnostic techniques which detect specific allergenic epitopes have been developed. Several newer therapies are promising.  相似文献   
93.
The Ly49 family of natural killer (NK) receptors regulates NK cell function by sensing major histocompatibility complex (MHC) class I. Ly49 receptors show complex patterns of MHC class I cross-reactivity and, in certain cases, peptide selectivity. To investigate whether specificity differences result from topological differences in MHC class I engagement, we determined the structure of the peptide-selective receptor Ly49C in complex with H-2K(b). The Ly49C homodimer binds two MHC class I molecules in symmetrical way, a mode distinct from that of Ly49A, which binds MHC class I asymmetrically. Ly49C does not directly contact the MHC-bound peptide. In addition, MHC crosslinking by Ly49C was demonstrated in solution. We propose a dynamic model for Ly49-MHC class I interactions involving conformational changes in the receptor, whereby variations in Ly49 dimerization mediate different MHC-binding modes.  相似文献   
94.
We describe the clinical and demographic characteristics, virological follow-up, and management of five confirmed monkeypox cases from New Delhi, India without any international travel history. The viral load kinetics and viral clearance were estimated in oropharyngeal swabs (OPS), nasopharyngeal swabs (NPS), EDTA blood, serum, urine, and various lesion specimens on every fourth day of follow-up ranging from 5 to 24 post onset day (POD) of illness. All five cases presented with mild to moderate-grade intermittent fever, myalgia, and lesions on the genitals, groins, lower limb, trunk, and upper limb. Four cases had non-tender firm lymphadenopathy. No secondary complications or sexually transmitted infections were recorded in these cases except for the presence of viral hepatitis B infection marker hepatitis B virus surface antigen (HBsAg) in one case. All the cases were mild and had a good recovery. A higher viral load was detected in lesion fluid (POD 9), followed by lesion roof (POD 9), urine (POD 5), lesion base (POD 5), and OPS/NPS (POD 5). The monkeypox virus (MPXV) DNA was detected in clinical samples from 5th to 24th POD. These monkeypox cases without international travel history suggest the underdiagnosed monkeypox infection in the community. This emphasizes the need for active surveillance of MPXV in the high-risk population such as men having sex with men and female sex workers.  相似文献   
95.
96.
Arteriovenous malformation (AVM) involving the external ears is relatively uncommon in adults. Arteriovenous malformations typically present during childhood and rarely manifest during adulthood in the head and neck region. Symptomatic arteriovenous malformations often pose difficult therapeutic challenges. We report a case of large arteriovenous malformation of the external ear in a 21-year-old female.  相似文献   
97.
We investigated the periodic characteristics of bursting discharge in renal sympathetic nerve activity (RSNA) in conscious rats. Employing a discrete fast Fourier transform algorithm, a power spectrum analysis was used to quantify periodicities present in rectified and integrated RSNA whose signal-to-noise ratio in the recordings was greater than six. In conscious rats with intact baroreceptors, RSNA was characterized by four frequency components occurring at about 0.5, 1.5, 6, and 12 Hz, which corresponded to the low-frequency fluctuation of heart rate, respiration, and frequency of heart beat, and its harmonics, respectively. After intravenous infusion of sodium nitroprusside (SNP) to elicit reflex increases in RSNA and heart rate, the power for the component at 6 Hz followed the changes in heart beat frequency and was significantly increased, while those for the three other components were attenuated or experienced no change. In sino-aortic denervated (SAD) conscious rats, all four components were abolished, and the power spectrum was well fitted by a flat or Lorentzian curve, suggesting an almost random pattern. Only a respiratory-related component, which suggested common central modulation, appeared sporadically for short periods but was absent for the most part. Therefore most of this component together with the low-frequency component was also likely due to the baroreceptor-dependent peripheral modulation. The activity was sorted in 15 subgroups on the basis of spike amplitudes in the RSNA. Each subgroup showed frequency characteristics similar to the whole nerve activity. These results suggest that all periodicity in the RSNA of conscious rats with intact baroreceptors is caused by the baroreceptor input.  相似文献   
98.
Medulloepitheliomas are rare congenital tumours arising from the epithelium lining the medullary tube. They are usually detected in the first decade of life. They may be teratoid or non-teratoid. Regional and distant metastases are rare. Extraocular extension of disease appears to be the most important prognostic feature. Surgical resection is the usual mode of treatment. The role of other adjuvant modalities is as yet unclear.  相似文献   
99.
Macular serpiginous choroiditis   总被引:1,自引:0,他引:1  
PURPOSE: To report a variant form of serpiginous choroiditis, that initially or predominantly involved the macular area. METHODS: Nine eyes of 6 patients with the macular form of serpiginous choroiditis were evaluated clinically and angiographically in a longitudinal fashion for a period of 12-36 months. The active stage and the recurrences were treated by oral and periocular cortico steroids; and two patients were supplemented with oral azathioprine. Most of these patients were referred to our center with varied diagnoses. RESULTS: In this group, 4 were male and 2 were female with an average age of 30.5 years. Three patients had bilateral macular lesions, two had typical serpiginous choroiditis in the fellow eye and the remaining one had unilateral macular involvement alone. The initial visual acuity was 6/60 or less in 60% eyes whereas the final visual acuity was 6/18 or better in 66% eyes. Angiographic findings were typical of serpiginous choroiditis characterised by early hypofluorescence followed by leakage and staining of the borders and the lesion itself without any evidence of choroidal ischaemia or retinal vascular abnormalities. CONCLUSION: The macular variant of serpiginous choroiditis can mimic many other macular pathologic lesions, thus posing a diagnostic dilemma. Because of its relentless destructive course, early diagnosis and prompt treatment is required to prevent sight-threatening complications.  相似文献   
100.
PURPOSE: To develop and evaluate an immunoanalytical method for the detection of beta- and gamma-crystallins and anti-crystallin antibodies. MATERIALS AND METHODS: Beta and gamma-crystallins isolated from rat lens were used as immunogens to raise polyclonal antibodies in rabbits. Antibody capture assay and western blot analysis showed that the antibodies to beta- and gamma-crystallins were specific. An indirect competitive enzyme linked immunosorbent assay (ELISA) developed to quantitate beta- and gamma-crystallin showed an IC50 value of 70 ng and 65 ng, respectively, based on regression analysis. Spiking studies with purified beta-crystallin antibodies showed that 33 ng of the purified antibody gave an absorbance of 1.1 at 450 nm, indicating the sensitivity of the method. RESULTS: Antibodies to beta- and gamma-crystallins were not detected in serum samples of the cataractous CFY/NIN rats (used as an animal model for induction of experimental cataract by feeding high galactose diet). However, the cataractous rat serum samples effectively displaced beta- and gamma-crystallin antibodies, indicating that these crystallins leak during cataract formation. The concentration of beta- and gamma-crystallins in the rat serum, as analysed by indirect competitive ELISA, was found to be in the range of 17.6-81.6 micrograms/ml [corrected] and 12.4-19.6 micrograms/ml, respectively. CONCLUSIONS: The methodology developed in the present study may find application as a biochemical tool in molecular epidemiology of cataract.  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