全文获取类型
收费全文 | 8515篇 |
免费 | 449篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 133篇 |
儿科学 | 221篇 |
妇产科学 | 143篇 |
基础医学 | 1114篇 |
口腔科学 | 575篇 |
临床医学 | 864篇 |
内科学 | 1446篇 |
皮肤病学 | 329篇 |
神经病学 | 735篇 |
特种医学 | 181篇 |
外科学 | 734篇 |
综合类 | 35篇 |
一般理论 | 6篇 |
预防医学 | 1137篇 |
眼科学 | 124篇 |
药学 | 582篇 |
中国医学 | 56篇 |
肿瘤学 | 587篇 |
出版年
2023年 | 60篇 |
2022年 | 98篇 |
2021年 | 205篇 |
2020年 | 139篇 |
2019年 | 198篇 |
2018年 | 220篇 |
2017年 | 161篇 |
2016年 | 238篇 |
2015年 | 270篇 |
2014年 | 325篇 |
2013年 | 471篇 |
2012年 | 692篇 |
2011年 | 834篇 |
2010年 | 433篇 |
2009年 | 354篇 |
2008年 | 562篇 |
2007年 | 667篇 |
2006年 | 582篇 |
2005年 | 541篇 |
2004年 | 473篇 |
2003年 | 382篇 |
2002年 | 366篇 |
2001年 | 65篇 |
2000年 | 62篇 |
1999年 | 71篇 |
1998年 | 65篇 |
1997年 | 57篇 |
1996年 | 41篇 |
1995年 | 34篇 |
1994年 | 35篇 |
1993年 | 31篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 18篇 |
1989年 | 28篇 |
1988年 | 10篇 |
1987年 | 17篇 |
1986年 | 19篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1975年 | 8篇 |
1974年 | 9篇 |
1973年 | 9篇 |
1972年 | 6篇 |
排序方式: 共有9002条查询结果,搜索用时 15 毫秒
61.
Expression of Matrix Metalloproteinases and Their Tissue Inhibitors in Human Brain Tumors 总被引:16,自引:0,他引:16
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Klaus Lampert Uwe Machein Mrcia Regina Machein Walter Conca Hans Hartmut Peter Benedikt Volk 《The American journal of pathology》1998,153(2):429-437
In this study, we investigated the expression patterns of 15 matrix metalloproteinases (MMPs) and three tissue inhibitors of metalloproteinase in gliomas, medulloblastomas, and normal brain tissue. By Northern blot analysis we found increased levels of mRNAs encoding for gelatinase A, gelatinase B, two membrane-type MMPs (mt1- and mt2-MMP), and tissue inhibitors of metalloproteinase-1 in glioblastomas and medulloblastomas. We observed a significant increase of mt1-MMP, gelatinase A, gelatinase B, and tissue inhibitors of metalloproteinase-1 in glioblastomas as compared with low-grade astrocytomas, anaplastic astrocytomas, and normal brain. In medulloblastomas, the expression of mt1-MMP, mt2-MMP, and gelatinase A were also increased, but to a lesser extent than that observed in glioblastomas. These data were confirmed at the protein level by immunostaining analysis. Moreover, substrate gel electrophoresis showed that the activated forms of gelatinases A and B were present in glioblastomas and medulloblastomas. These results suggest that increased expression of mt1-MMP/gelatinase A is closely related to the malignant progression observed in gliomas. Furthermore, the present study demonstrates, to our knowledge for the first time, that medulloblastomas express high levels of MMP. 相似文献
62.
Riedl M Czech T Slootweg J Czernin S Hainfellner JA Schima W Vierhapper H Luger A 《Endocrine pathology》1995,6(2):159-166
This report describes a case of lymphocytic hypophysitis in a 63-year-old man who presented with symptoms of a pituitary mass
lesion associated with hypothyroidism and hypogonadism. Postoperative endocrinological testing demonstrated gonadotropic,
thyrotropic, and corticotropic hypopituitarism, and the patient was commenced on replacement therapy with hydrocortisone and
levothyroxine. Histological examination of the pituitary tissue obtained by transsphenoidal surgery revealed lymphocytic hypophysitis
without evidence of a pituitary adenoma. The vast majority of patients with lymphocytic hypophysitis are women particularly
during pregnancy and the puerperium. Until recently only four men were reported in the literature. The pathogenesis of lymphocytic
hypophysitis is uncertain but autoimmune mechanisms are possibly involved. 相似文献
63.
Camara AA Silva JM Ferriani VP Tobias KR Macedo IS Padovani MA Harsi CM Cardoso MR Chapman MD Arruda E Platts-Mills TA Arruda LK 《The Journal of allergy and clinical immunology》2004,113(3):551-557
BACKGROUND: Risk factors for acute wheezing among children in subtropical areas are largely unknown. OBJECTIVE: To investigate the role of viral infections, allergen sensitization, and exposure to indoor allergens as risk factors for acute wheezing in children 0 to 12 years old. METHODS: One hundred thirty-two children 0 to 12 years of age who sought emergency department care for wheezing and 65 children with no history of wheezing were enrolled in this case-control study. Detection of respiratory syncytial virus antigen, rhinovirus and coronavirus RNA, adenovirus, influenza, and parainfluenza antigens was performed in nasal washes. Total IgE and specific IgE to mites, cockroach, cat, and dog were measured with the CAP system. Major allergens from mites, cockroach, cat, and dog were quantified in dust samples by ELISA. Univariate and multivariate analyses were performed by logistic regression. RESULTS: In children under 2 years of age, infection with respiratory viruses and family history of allergy were independently associated with wheezing (odds ratio, 15.5 and 4.2; P = .0001 and P = .008, respectively). Among children 2 to 12 years old, sensitization to inhalant allergens was the major risk factor for wheezing (odds ratio, 2.7; P = .03). High-level allergen exposure, exposure to tobacco smoke, and lack of breast-feeding showed no association with wheezing. CONCLUSIONS: Some risk factors for wheezing previously identified in temperate climates were present in a subtropical area, including respiratory syncytial virus infection in infants and allergy in children older than 2 years. Rhinovirus was not associated with wheezing and did not appear to be a trigger for asthma exacerbations. 相似文献
64.
Kummrow M Meli ML Haessig M Goenczi E Poland A Pedersen NC Hofmann-Lehmann R Lutz H 《Clinical and diagnostic laboratory immunology》2005,12(10):1209-1215
To determine the prevalence of antibodies to feline coronavirus (FCoV) serotypes 1 and 2 in Switzerland and their association with different disease manifestations, a serological study based on immunofluorescence tests was conducted with Swiss field cats using transmissible gastroenteritis virus (TGEV), FCoV type 1 and FCoV type 2 as antigens. A total of 639 serum samples collected in the context of different studies from naturally infected cats were tested. The current study revealed that, with an apparent prevalence of 83%, FCoV serotype 1 is the most prevalent serotype in Switzerland. FCoV type 1 viruses induced higher antibody titers than FCoV type 2, and were more frequently associated with clinical signs and/or feline infectious peritonitis. The antibody development in seven cats experimentally infected with FCoV type 1 revealed that, with progressing duration of infection, antibodies to FCoV type 1 significantly increased over those to FCoV type 2. There was a significant relationship between antibody titers against TGEV, FCoV 1, and FCoV 2 and TGEV antigen detected the highest proportion of seropositive cats. We conclude that a vaccine against FCoV should be based on FCoV type 1-related antigens and that for serodiagnosis of FCoV infection TGEV should be used to attain the highest diagnostic efficiency. When serology is used in addition to clinical signs, hematology, and clinical chemistry results as an aid to diagnose clinical FIP, TGEV shows a diagnostic efficiency equal to that of a FCoV antigen. 相似文献
65.
Barbara Riond Marina L. Meli Ueli Braun Peter Deplazes Kaspar Joerger Rudolf Thoma Hans Lutz Regina Hofmann-Lehmann 《Comparative clinical pathology》2008,17(3):171-177
An outbreak of a fatal haemolytic anaemia in a dairy herd of cattle in Switzerland was shown to be associated with infections
with five vector-borne pathogens, namely Anaplasma marginale, A. phagocytophilum, Babesia bigemina, a Theileria spp belonging to the buffeli/sergenti/orientalis complex and haemotrophic Mycoplasma spp. The latter three had not been documented before this outbreak in Switzerland. To characterise the haematological and blood
chemical changes in these unique cows, packed cell volume was determined in all 286 blood samples, blood smears, and complete
haematology were performed from 285 and 173 blood samples, respectively, and biochemical parameters were assayed in 105 serum
samples. Regenerative anaemia was the key sign of illness. Red blood cells of anaemic cattle were hypochromic and macrocytic.
Anaemic animals had reduced platelet cell counts and increased total white cell counts. In addition, increased serum bilirubin,
blood aspartate aminotransferase, gamma glutamyltransferase, glutamic dehydrogenase and blood urea nitrogen and decreased
magnesium, calcium and albumin levels were found in anaemic cattle when compared to animals with normal packed cell volume.
Most changes could not be attributed to a single infection. A. marginale seemed to be important in causing the outbreak, but co-infections may have aggravated the disease development and clinical
signs. Thus, when encountering cattle with haemolytic anaemia, all of the mentioned pathogens should be included as differential
diagnosis. 相似文献
66.
Kaufmann R Fölster-Holst R Höger P Thaçi D Löffler H Staab D Bräutigam M;CASMCDE-Study Group 《The Journal of allergy and clinical immunology》2004,114(5):1183-1188
BACKGROUND: Data on the efficacy of pimecrolimus cream 1% within the first days of treatment are scarce, as in previous studies, the first postbaseline assessment was performed only after 1 week. OBJECTIVE: We sought to investigate the onset of action of pimecrolimus cream 1% in infants with mild to very severe atopic eczema. METHODS: We used pimecrolimus cream 1% (n = 129) or vehicle cream (n = 66) administered in a double-blind manner for 4 weeks and then open-label pimecrolimus cream 1% for 12 weeks, with a 4-week follow-up period. RESULTS: Pimecrolimus cream 1% reduced the mean Eczema Area and Severity Index at 4 weeks by 71.5% compared with an increase of 19.4% with vehicle ( P < .001). The reduction in the Eczema Area and Severity Index with pimecrolimus cream 1% was significant at day 4 (38.5% vs 17.6% increase with vehicle). Significant improvements in caregivers' assessments of pruritus and sleep loss were observed with pimecrolimus cream 1% by day 2 ( P < .03) and day 3 ( P = .002), respectively, compared with vehicle. Responses to pimecrolimus cream 1% were sustained during the open-label phase, and pimecrolimus cream 1% was well tolerated. Symptoms of atopic eczema returned gradually after discontinuation. CONCLUSION: Pimecrolimus cream 1% was well tolerated and effective in patients with mild to very severe atopic eczema, with rapid onset of action and no disease rebound after discontinuation. 相似文献
67.
Nascimento Jdos S Giambiagi-deMarval M de Oliveira SS Ceotto H dos Santos KR Bastos Mdo C 《Research in microbiology》2005,156(8):837-842
Among 363 strains of Staphylococcus aureus, 21 were shown to produce bacteriocins (Bac), antimicrobial peptides with potential biotechnological applications. This collection includes strains which are either isolated from food, patients and healthy cattle, or are involved in subclinical bovine mastitis. From these 21 strains, 17 were shown to carry closely-related 8.0-kb Bac plasmids encoding bacteriocins either identical to or similar to aureocin A70, a bacteriocin able to inhibit strains of Listeria monocytogenes, a food-borne pathogen. Such findings prompted us to investigate the genetic relationships among these Bac+ strains. To obtain more discriminatory results, a combined analysis of AP-PCR, rep-PCR, and a modified PCR technique that we designated SD-PCR was employed. The 17 Bac+ strains harboring 8.0-kb Bac plasmids exhibited seven fingerprint patterns. One such genotype was composed of 8 out of the 11 strains associated with bovine mastitis, which suggests the prevalence of a clone of Bac+ strains involved in this animal infection carrying 8.0-kb Bac plasmids. Our data support the assumption that Bac+ strains of S. aureus carrying genetically related 8.0-kb Bac plasmids do not belong to a single clone. It seems, therefore, that 8.0-kb Bac plasmids have spread horizontally among different S. aureus strains. There also seems to be genetic diversity among the remaining Bac+ strains analyzed. 相似文献
68.
Maya Kummrow Marina L. Meli Michael Haessig Enikoe Goenczi Amy Poland Niels C. Pedersen Regina Hofmann-Lehmann Hans Lutz 《Clinical and Vaccine Immunology : CVI》2005,12(10):1209-1215
To determine the prevalence of antibodies to feline coronavirus (FCoV) serotypes 1 and 2 in Switzerland and their association with different disease manifestations, a serological study based on immunofluorescence tests was conducted with Swiss field cats using transmissible gastroenteritis virus (TGEV), FCoV type 1 and FCoV type 2 as antigens. A total of 639 serum samples collected in the context of different studies from naturally infected cats were tested. The current study revealed that, with an apparent prevalence of 83%, FCoV serotype 1 is the most prevalent serotype in Switzerland. FCoV type 1 viruses induced higher antibody titers than FCoV type 2, and were more frequently associated with clinical signs and/or feline infectious peritonitis. The antibody development in seven cats experimentally infected with FCoV type 1 revealed that, with progressing duration of infection, antibodies to FCoV type 1 significantly increased over those to FCoV type 2. There was a significant relationship between antibody titers against TGEV, FCoV 1, and FCoV 2 and TGEV antigen detected the highest proportion of seropositive cats. We conclude that a vaccine against FCoV should be based on FCoV type 1-related antigens and that for serodiagnosis of FCoV infection TGEV should be used to attain the highest diagnostic efficiency. When serology is used in addition to clinical signs, hematology, and clinical chemistry results as an aid to diagnose clinical FIP, TGEV shows a diagnostic efficiency equal to that of a FCoV antigen. 相似文献
69.
Infant rats exhibit sensitive-period odor learning characterized by olfactory bulb neural changes and odor preference acquisitions critical for survival. This sensitive period is coincident with low endogenous corticosterone (CORT) levels and stress hyporesponsivity. The authors hypothesized that low corticosterone levels modulate sensitive-period learning. They assessed the effects of manipulating CORT levels by increasing and removing CORT during (Postnatal Day 8) and after (Postnatal Day 12) the sensitive period. Results show that (a) exogenous CORT prematurely ends sensitive-period odor-shock-induced preferences; (b) adrenalectomy developmentally extends the sensitive period as indicated by odor-shock-induced odor-preference learning in older pups, whereas CORT replacement can reinstate fear learning; and (c) CORT manipulation modulates olfactory bulb correlates of sensitive-period odor learning in a manner consistent with behavior. 相似文献
70.
Gamma-hydroxybutyric acid is a gamma-aminobutyric acid analogue which can be found in the human brain and is believed to be a neurotransmitter in the central nervous system. In animal experiments as well as in humans gamma-hydroxybutyric acid has been shown to alleviate the symptoms of the alcohol withdrawal syndrome. 299 patients, who were admitted to hospital for reasons primarily unrelated to their alcohol dependence, were treated with gamma-hydroxybutyric acid when symptoms of the alcohol withdrawal syndrome occurred. Gamma-hydroxybutyric acid was usually given at a daily dose of 50 mg/kg in 3 divided doses, the clinical course of the patients was followed for 7 days or until discharge from hospital. Patients were 214 men and 82 women aged 18-87 years. The reasons for admission to hospital were frequently internal diseases, neurological/psychiatric problems, trauma or surgery. At the start of gamma-hydroxybutyric acid treatment, tremor was present in 81% of patients, sweating in 76% and unrest in 92%. Symptoms occurred 1-72 hours after admission. The efficacy of gamma-hydroxybutyric acid to ameliorate or suppress the symptoms of the alcohol withdrawal syndrome was judged to be excellent in 57%, good in 34%, fair in 18%, insufficient in 3% of patients. Drug tolerance was judged to be excellent in 79%, good in 17%, fair in 2% and poor only in 1% of patients. Adverse events were rare and mild. It is concluded that gamma-hydroxybutyric acid is an attractive alternative to tranquilizers in the management of the alcohol withdrawal syndrome in hospital. 相似文献