全文获取类型
收费全文 | 5679篇 |
免费 | 321篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 139篇 |
妇产科学 | 90篇 |
基础医学 | 588篇 |
口腔科学 | 180篇 |
临床医学 | 539篇 |
内科学 | 1203篇 |
皮肤病学 | 73篇 |
神经病学 | 318篇 |
特种医学 | 236篇 |
外科学 | 983篇 |
综合类 | 139篇 |
一般理论 | 1篇 |
预防医学 | 361篇 |
眼科学 | 161篇 |
药学 | 619篇 |
中国医学 | 63篇 |
肿瘤学 | 240篇 |
出版年
2023年 | 84篇 |
2022年 | 191篇 |
2021年 | 280篇 |
2020年 | 172篇 |
2019年 | 198篇 |
2018年 | 251篇 |
2017年 | 146篇 |
2016年 | 168篇 |
2015年 | 154篇 |
2014年 | 222篇 |
2013年 | 298篇 |
2012年 | 420篇 |
2011年 | 430篇 |
2010年 | 212篇 |
2009年 | 171篇 |
2008年 | 307篇 |
2007年 | 313篇 |
2006年 | 267篇 |
2005年 | 217篇 |
2004年 | 202篇 |
2003年 | 188篇 |
2002年 | 148篇 |
2001年 | 88篇 |
2000年 | 89篇 |
1999年 | 89篇 |
1998年 | 36篇 |
1997年 | 32篇 |
1996年 | 19篇 |
1995年 | 29篇 |
1994年 | 23篇 |
1993年 | 21篇 |
1992年 | 54篇 |
1991年 | 47篇 |
1990年 | 43篇 |
1989年 | 50篇 |
1988年 | 52篇 |
1987年 | 40篇 |
1986年 | 31篇 |
1985年 | 28篇 |
1984年 | 28篇 |
1983年 | 24篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 25篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1976年 | 15篇 |
1974年 | 16篇 |
1973年 | 10篇 |
排序方式: 共有6032条查询结果,搜索用时 15 毫秒
61.
Glycosylated hemoglobin was measured, by a colorimetric method, in 49 patients with sickle cell anemia attending Khartoum Teaching Hospital. The level obtained (4.9%, SD 1.3) was significantly lower than the control value (5.6%, SD 0.2; p less than 0.0025). Expressed as percentage of the control value, the glycosylated hemoglobin level in these patients was 81%. This falls midway between the 90% reported in a benign form of sickle cell anemia in Saudi Arabia and the 58% reported in a severe form in an American Black group, which gives support to the observed heterogeneity of sickle cell anemia. Alternatively, glycosylated hemoglobin level in 27 subjects with sickle cell trait (5.6%, SD 0.2) was identical to that of the controls. The state of hemolysis in the sickle cell anemia patients, as indicated by bilirubin levels, did not correlate with the glycosylated hemoglobin values. Although glycosylated hemoglobin measurement is affected by red cell survival, it does not reflect the state of ongoing hemolysis. 相似文献
62.
Sehrish Bilal Muhammad Nasir M. Mudassir Hassan Muhammad Fayyaz ur Rehman Amtul Jamil Sami Akhtar Hayat 《RSC advances》2022,12(26):16860
Herein, an electrochemical biosensor has been prepared to assess the sensitivity of an organophosphate insecticide, malathion, to acetylcholinesterase (AChE) enzyme of three insects including Apis mellifera (honeybee), Tribolium castaneum (red flour beetle), and Zootermopsis nevadensis (dampwood termite). A composite of nickel chromite (NiCr2O4) and graphitic carbon nitride (g-C3N4) was prepared and characterized for its morphological, chemical and electrical properties. The NiCr2O4/g-C3N4 composite integrated pencil graphite electrodes were used to covalently immobilize insect AChE enzymes and amperometric response of bioelectrodes was determined through cyclic voltammetry. The prepared bioelectrodes exhibited high enzyme immobilization efficiency and electro-catalytic performance. The integrated bioelectrodes could efficiently detect malathion induced inhibition of insects'' AChEs. The linear ranges for malathion were found to be 0.1–1.6 μM, 1–40 nM and 2–100 nM, and LODs were 2 nM, 0.86 nM and 2.3 nM for A. mellifera, T. castaneum, and Z. nevadensis, respectively. Additionally, the biosensing platform developed using A. mellifera AChE was found highly sensitive and effective for malathion recoveries from spiked wheat flour samples with high recovery rates. Moreover, the proposed method was adequately reproducible and selective. The results revealed that A. mellifera AChE is less sensitive to inhibition by malathion as compared to T. castaneum, and Z. nevadensis AChE. The experimental results were validated through computational docking of malathion with insect AChEs and the results were in correspondence to experimental outcomes. The proposed method can be a plausible alternate to conventional analytical methods to assess the pesticide sensitivity and toxicity of various compounds against insect enzymes.An innovative electrochemical assay has been established to determine pesticide sensitivity against acetylcholinesterase and possible toxicity against insects. The analytical efficiency of three common insect AChEs was determined through this method. 相似文献
63.
Benter IF Yousif MH Hollins AJ Griffiths SM Akhtar S 《Journal of vascular research》2005,42(4):284-291
Contribution of receptor tyrosine kinase activation to development of diabetes-induced renal artery dysfunction is not known. We investigated the ability of a chronic administration of genistein, a broad-spectrum inhibitor of tyrosine kinases (TKs), and AG1478, a specific inhibitor of epidermal growth factor receptor (EGFR) TK activity, to modulate the altered vasoreactivity of isolated renal artery ring segments to common vasoconstrictors in streptozotocin-induced diabetes. In diabetic renal artery, the vasoconstrictor responses induced by norepinephrine, endothelin-1 and angiotensin II were significantly increased. Inhibition of TKs or the EGFR pathway did not affect the agonist-induced vasoconstrictor responses in the non-diabetic control animals. However, inhibition of TKs by genistein or EGFR TK by AG1478 treatment produced a significant normalization of the altered agonist-induced vasoconstrictor responses without affecting blood glucose levels. Treatment with diadzein, an inactive analogue of genistein, did not affect the vasoconstrictor responses in the diabetic animals. Western blotting showed that phosphorylated EGFR protein levels were increased in vehicle-treated diabetic animals. In renal arteries from AG1478-treated diabetic animals, EGFR protein levels were similar to non-diabetic control animals. These data suggest that activation of TK-mediated pathways, including the EGFR TK signalling pathway, are involved in the development of diabetic vascular dysfunction in the renal artery. 相似文献
64.
Mohammed Al-Beltagi Nermin Kamal Saeed Adel Salah Bediwy Yasser El-Sawaf 《World journal of gastroenterology : WJG》2021,27(16):1716-1727
The coronavirus disease 2019 (COVID-19) pandemic is a threat worldwide for individuals of all ages, including children. Gastrointestinal manifestations could be the initial presenting manifestation in many patients, especially in children. These symptoms are more common in patients with severe disease than in patients with non-severe disease. Approximately 48.1% of patients had a stool sample that was positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral RNA. Children typically form 1%-8% of all laboratory-confirmed cases of SARS-CoV-2. Gastrointestinal manifestations of COVID-19 in children are not rare, with a prevalence between 0 and 88%, and a wide variety of presentations, including diarrhoea, vomiting, and abdominal pain, can develop before, with or after the development of respiratory symptoms. Atypical manifestations such as appendicitis or liver injury could also appear, especially in the presence of multisystem inflammatory disease. In this review, we discussed the epidemiology of COVID-19 gastrointestinal diseases in children as well as their implications on the diagnosis, misdiagnosis, prognosis, and faecal-oral transmission route of COVID-19 and the impact of gastrointestinal diseases on the gut microbiome, child nutrition, and disease management. 相似文献
65.
Islam MA Ahmed MU Begum N Chowdhury NA Khan AH Parquet Mdel C Bipolo S Inoue S Hasebe F Suzuki Y Morita K 《Japanese journal of infectious diseases》2006,59(2):85-91
During the febrile illness epidemic in Bangladesh in 2002, 58 people died out of the 6,132 affected. Two hundred hospitalized patients were analyzed clinically, serologically and virologically to determine the features of this dengue infection. Among the 10- to 70-year-old age group of the 200 clinically suspected dengue patients, 100 (50%) were confirmed as dengue cases by virus isolation and dengue IgM-capture ELISA. Of the 100 dengue-confirmed cases, the mean age was 29.0 (+/-12.4). The possible dengue secondary infection rate determined by Flavivirus IgG-indirect ELISA was 78% in 2002. Eight dengue virus strains were isolated, representing the first dengue virus isolation in the country, and all of the strains were dengue virus type-3 (DEN-3). Sequence data for the envelope gene of the DEN-3 Bangladeshi isolates were used in a phylogenetic comparison with DEN-3 from other countries. A phylogenetic analysis revealed that all 8 strains of DEN-3 were clustered within a well-supported independent sub-cluster of genotype II and were closely related to the Thai isolates from the 1990s. Therefore, it is likely that the currently circulating DEN-3 viruses entered Bangladesh from neighboring countries. 相似文献
66.
Saeed Jerban Yajun Ma Lidi Wan Adam C. Searleman Hyungseok Jang Robert L. Sah Eric Y. Chang Jiang Du 《NMR in biomedicine》2019,32(2)
Intracortical bone porosity is a key microstructural parameter that determines bone mechanical properties. While clinical MRI visualizes the cortical bone with a signal void, ultrashort echo time (UTE) MRI can acquire high signal from cortical bone, thus enabling quantitative assessments. Magnetization transfer (MT) imaging combined with UTE‐MRI can indirectly assess protons in the bone collagenous matrix, which are inversely related to porosity. This study aimed to examine UTE‐MT MRI techniques to evaluate intracortical bone porosity. Eighteen human cortical bone specimens from the tibial and fibular midshafts were scanned using UTE‐MT sequences on a clinical 3 T MRI scanner and on a high‐resolution micro‐computed tomography (μCT) scanner. A series of MT pulse saturation powers (500°, 1000°, 1500°) and frequency offsets (2, 5, 10, 20, 50 kHz) were used to measure the macromolecular fraction (MMF) and macromolecular T2 (T2MM) using a two‐pool MT model. The measurements were made on 136 different regions of interest (ROIs). ROIs were selected at three cortical bone layers (from endosteum to periosteum) and four anatomical sites (anterior, mid‐medial, mid‐lateral, and posterior) to provide a wide range of porosity. MMF showed moderate to strong correlations with intracortical bone porosity (R = ?0.67 to ?0.73, p < 0.01) and bone mineral density (BMD) (R = +0.46 to +0.70, p < 0.01). Comparing the average MMF between cortical bone layers revealed a significant increase from the endosteum towards the periosteum. Such a pattern was in agreement with porosity reduction and BMD increase towards the periosteum. These results suggest that the two‐pool UTE‐MT technique can potentially serve as a novel and accurate tool to assess intracortical bone porosity. 相似文献
67.
Arash Salmaninejad Arezoo Gowhari Seyedmojtaba Hosseini Saeed Aslani Meysam Yousefi Tayyeb Bahrami 《Journal of immunotoxicology》2017,14(1):137-151
Behçet’s disease (BD) is a chronic autoimmune condition primarily prevalent in populations along the Mediterranean Sea. The exact etiology of BD has not been fully explained yet, but the disease occurrence is associated with a genetic factor, human leukocyte antigen (HLA)-B51 antigen. Among the various immunodysfunctions that are found in BD, patients are increased neutrophil motility and superoxide production, as well as elevated production of tumor necrosis factor (TNF)-α and decreased production of interleukin (IL)-10. Elevated levels of inflammatory cytokines like IL-1 and IL-17 in BD have been found associated with aberrant expression of microRNA. Gene polymorphisms in BD patients have been observed in molecules involved in responses to pathogens that can ultimately modulate the host antimicrobial response. Moreover, several single nucleotide polymorphisms (SNPs) have been reported in genes encoding chemokines and adhesion molecules; many of these changes manifest as increases in vascular inflammation and vascular damage. Lastly, genetic and epigenetic changes have been suggested as involved in the pathogenesis of BD. Modifications in DNA methylation have been found in BD patient monocytes and lymphocytes, leading to adverse function of these cells. This review presents a comprehensive compilation of the literature with regard to the immunodysfunction underlying BD, as well as of the genetics, newly described clinical specifications and novel treatment strategies using immunomodulants based on the current understanding of BD. 相似文献
68.
Subcutaneous immunization with a novel immunogenic candidate (urease) confers protection against Brucella abortus and Brucella melitensis infections 下载免费PDF全文
Morteza Abkar Jafar Amani Abbas Sahebghadam Lotfi Gholamreza Nikbakht Brujeni Saeed Alamian Mehdi Kamali 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2015,123(8):667-675
Brucellosis is a world prevalent endemic illness that is transmitted from domestic animals to humans. Brucella spp. exploits urease for survival in the harsh conditions of stomach during the gastrointestinal infection. In this study, we examined the immune response and the protection elicited by using recombinant Brucella urease (rUrease) vaccination in BALB/c mice. The urease gene was cloned in pET28a and the resulting recombinant protein was employed as subunit vaccine. Recombinant protein was administered subcutaneously and intraperitoneally. Dosage reduction was observed with subcutaneous (SC) vaccination when compared with intraperitoneal (IP) vaccination. rUrease induced mixed Th1–Th2 immune responses with high titers of specific IgG1 and IgG2a. In lymphocyte proliferation assay, splenocytes from IP and SC‐vaccinated mice displayed a strong recall proliferative response with high amounts of IL‐4, IL‐12 and IFN‐γ production. Vaccinated mice were challenged with virulent Brucella melitensis, B. abortus and B. suis. The SC vaccination route exhibited a higher degree of protection than IP vaccination (p value ≤ 0.05). Altogether, our results indicated that rUrease could be a useful antigen candidate for the development of subunit vaccines against brucellosis. 相似文献
69.
Naveed Khan Muhammad Shoaib Akhtar Barkat Ali Khan Valdir de Andrade Braga Adam Reich 《Archives of Medical Science》2015,11(6):1261-1271
Introduction
Numerous herbal medicines have been recommended for the treatment of different diseases. Achyranthes aspera, Linn. (Family: Amaranthaceae), popularly known as Charchitta or Pitpapra, is commonly used by traditional healers for the treatment of fever, malaria, dysentery, asthma, arterial hypertension, pneumonia, and diabetes. The root extract is well reputed for its insect molting hormonal activity. This investigation was conducted to evaluate the effects of saponins from Achyranthes aspera seeds on the serum lipid profile of albino rats fed a high cholesterol diet.Material and methods
Hypolipidemic, antioxidant and hepatoprotective activities of these saponins were tested as described previously. To determine the mechanism underlying the observed effects, serum antioxidant status was assessed according to ABTS (2,2’-azino-bis-3-ethylbenzo-thiazoline-6-sulfonic acid), superoxide dismutase and ferric ion reducing antioxidant power (FRAP) assays in saponin-treated hyperlipidemic animals. Liver enzyme levels were determined to reveal any possible hepatotoxicity.Results
Four-week oral administration of A. aspera seed saponins produced a significant (p < 0.05) decrease of total cholesterol, total triglycerides and LDL-C and a significant increase of HDL-C level in hyperlipidemic rats. Treatment with A. aspera seed saponins also showed a significant (p < 0.01) improvement of serum antioxidant status in tested animals. No significant hepatotoxicity was produced by such treatment as the serum liver enzyme activity remained unaltered.Conclusions
Saponins from A. aspera seeds possess antihyperlipidemic and antioxidant properties which might lead to improvement of serum lipid profile and blood antioxidant status. Our findings support the folkloric use of this indigenous plant in the treatment of hyperlipidemia. However, its exact mechanism of action remains to be elucidated. 相似文献70.
Aliasghar Chalmeh Khalil Badiei Mehrdad Pourjafar Saeed Nazifi 《Inflammation research》2013,62(1):61-67