全文获取类型
收费全文 | 8537篇 |
免费 | 530篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 127篇 |
儿科学 | 267篇 |
妇产科学 | 266篇 |
基础医学 | 884篇 |
口腔科学 | 140篇 |
临床医学 | 776篇 |
内科学 | 2236篇 |
皮肤病学 | 80篇 |
神经病学 | 838篇 |
特种医学 | 329篇 |
外科学 | 947篇 |
综合类 | 93篇 |
一般理论 | 6篇 |
预防医学 | 974篇 |
眼科学 | 157篇 |
药学 | 556篇 |
中国医学 | 2篇 |
肿瘤学 | 414篇 |
出版年
2023年 | 32篇 |
2022年 | 19篇 |
2021年 | 173篇 |
2020年 | 84篇 |
2019年 | 169篇 |
2018年 | 191篇 |
2017年 | 160篇 |
2016年 | 145篇 |
2015年 | 173篇 |
2014年 | 282篇 |
2013年 | 389篇 |
2012年 | 630篇 |
2011年 | 692篇 |
2010年 | 377篇 |
2009年 | 373篇 |
2008年 | 567篇 |
2007年 | 690篇 |
2006年 | 640篇 |
2005年 | 614篇 |
2004年 | 581篇 |
2003年 | 533篇 |
2002年 | 466篇 |
2001年 | 102篇 |
2000年 | 73篇 |
1999年 | 82篇 |
1998年 | 104篇 |
1997年 | 77篇 |
1996年 | 59篇 |
1995年 | 69篇 |
1994年 | 47篇 |
1993年 | 45篇 |
1992年 | 47篇 |
1991年 | 28篇 |
1990年 | 34篇 |
1989年 | 62篇 |
1988年 | 37篇 |
1987年 | 23篇 |
1986年 | 22篇 |
1985年 | 17篇 |
1984年 | 31篇 |
1983年 | 18篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 16篇 |
1979年 | 7篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1973年 | 6篇 |
1971年 | 6篇 |
排序方式: 共有9092条查询结果,搜索用时 328 毫秒
81.
Staci A. Fischer Alan A. Harris John Segreti Larry J. Goodman Carl Langkop Margaret Swartz Ron Lollar Gordon M. Trenholme 《Clinical microbiology and infection》1996,1(3):175-178
Objective: To determine the incidence of infection with Escherichia coli O157:H7 in a tertiary referral center in Chicago, where a similar study had been performed in 1984, to evaluate cases of disease reported to the Illinois Department of Public Health (IDPH) in 1993, and to determine laboratory practices used to detect this infection throughout the state.
Methods: During a 6-month period in 1993, all stool specimens at Rush-Presbyterian-St Luke's Medical Center (RPSLMC) were tested for E. coli O157:H7. Reports of diagnosed E. coli O157:H7 cases investigated by IDPH were also reviewed. A survey of 73 hospitals in the Chicago area was performed to determine routine culturing practices, specifically, the selection of stool specimens for evaluation for this pathogen.
Results: In the RPSLMC survey, two cases were identified among 1985 samples (incidence 0.1%), similar to the 0.08% incidence detected in a similar study conducted at the same institution in 1984. Through passive surveillance, the IDPH received 44 reports of E. coli O157:H7 in 1993. The hospital survey revealed that, in the seven labs testing all stool specimens for E. coli O157:H7, an incidence of 16/8137 specimens (0.2%) was determined.
Conclusions: These data suggest that sporadic E. coli O157:H7 remains uncommon in Illinois and that the incidence may not have changed over a 9-year period. The low yield and substantial cost of culturing all stools suggest that only specimens from patients with bloody diarrhea should be evaluated routinely in areas of low endemicity. 相似文献
Methods: During a 6-month period in 1993, all stool specimens at Rush-Presbyterian-St Luke's Medical Center (RPSLMC) were tested for E. coli O157:H7. Reports of diagnosed E. coli O157:H7 cases investigated by IDPH were also reviewed. A survey of 73 hospitals in the Chicago area was performed to determine routine culturing practices, specifically, the selection of stool specimens for evaluation for this pathogen.
Results: In the RPSLMC survey, two cases were identified among 1985 samples (incidence 0.1%), similar to the 0.08% incidence detected in a similar study conducted at the same institution in 1984. Through passive surveillance, the IDPH received 44 reports of E. coli O157:H7 in 1993. The hospital survey revealed that, in the seven labs testing all stool specimens for E. coli O157:H7, an incidence of 16/8137 specimens (0.2%) was determined.
Conclusions: These data suggest that sporadic E. coli O157:H7 remains uncommon in Illinois and that the incidence may not have changed over a 9-year period. The low yield and substantial cost of culturing all stools suggest that only specimens from patients with bloody diarrhea should be evaluated routinely in areas of low endemicity. 相似文献
82.
Rainer Schulz Ron J. Oudiz Brian D. Guth Gerd Heusch 《Naunyn-Schmiedeberg's archives of pharmacology》1990,342(4):422-428
Summary -Adrenoceptor-mediated coronary vasoconstriction contributes to the initiation and aggravation of experimental and clinical myocardial ischaemia. However, the extent of 1- and 2-adrenoceptor-mediated constriction has not been characterized in the porcine coronary circulation despite the frequent use of this experimental model.Fifteen swine were anaesthetized with either -chloralose, enflurane or isoflurane to determine the amount of -adrenoceptor-mediated coronary constriction elicited by either the selective 1-adrenoceptor agonist methoxamine or the selective 2-adrenoceptor agonist azepexole. The left anterior descending coronary artery was cannulated and perfused by an external pump delivering constant blood flow from the carotid artery. Following bilateral cervical vagotomy and ß-adrenoceptor blockade with propranolol (2 mg kg–1), graded dosages of either one of the -adrenoceptor agonists (9–45 g kg–1 min–1) were infused into the coronary perfusion line while coronary arterial pressure (CAP) was measured through a distal side arm of the cannula to detect changes in coronary vascular resistance. Infusion of the -adrenoceptor agonists was terminated when systemic arterial pressure increased. Sonomicrometers were used to measure anterior left ventricular wall thickening for the assessment of regional contractile function. During methoxamine infusion, no increase in vascular resistance was observed during -chloralose, enflurane or isoflurane anaesthesia, whereas the infusion of azepexole increased CAP from 103 ± 31 mmHg to 120 ± 35 mmHg (-chloralose), from 101 ± 16 mmHg to 122 ± 11 mmHg (enflurane) and from 84 ± 20 mmHg to 94 ± 19 mmHg (isoflurane), respectively. In four additional swine anaesthetized with enflurane, the intracoronary infusion of the full catecholamine agonist noradrenaline in the presence of propranolol (6 mg kg–1) increased CAP from 98 ± 10 to 105 ± 10 mmHg prior to an increase in regional left ventricular function or systemic arterial pressure.These results indicate that there are no 1- and relatively little 2-adrenoceptor-mediated coronary constrictive effects in swine. Furthermore, neither -adrenoceptor agonist produced any detectable change in regional myocardial contractile function, regardless of the anaesthesia used.Supported by the German Research Foundation (He 1320/3-2). Dr. Guth is the recipient of a scholarship from the Alexander von Humboldt-Foundation.
Send offprint requests to G. Heusch at the above address 相似文献
83.
Anna M. Malkova Anna R. Gubal Anastasia L. Petrova Elena Voronov Ron N. Apte Konstantin N. Semenov Vladimir V. Sharoyko 《Immunology》2023,168(2):203-216
In recent years, pro-oncogenic mechanisms of the tumour microenvironment (ТМЕ) have been actively discussed. One of the main cytokines of the TМЕ is interleukin-1 beta (IL-1β), which exhibits proinflammatory properties. Some studies have shown an association between an increase in IL-1β levels and tumour progression. The purpose of this review is to analyse the pathogenic mechanisms induced by IL-1β in the TМЕ, as well as the diagnostic significance of the presence of IL-1β in patients with cancer and the efficacy of treatment with IL-1β inhibitors. According to the literature, IL-1β can induce an increase in tumour angiogenesis due to its effects on the differentiation of epithelial cells, pro-angiogenic molecule secretion and expression of adhesion molecules, thus increasing tumour growth and metastasis. IL-1β is also involved in the suppression of anti-tumour immune responses. The expression and secretion of IL-1β has been noted in various types of tumours. In some clinical studies, an elevated level of IL-1β was found to be associated with low efficacy of anti-cancer therapy and a poor prognosis. In most experimental and clinical studies, the use of IL-1β inhibitors contributed to a decrease in tumour mass and an increase in the response to anti-tumour drugs. 相似文献
84.
Standard staging and therapeutic approach to endometrial cancer involves lymph node sampling (LNS) at the time of total abdominal hysterectomy (TAH) and bilateral salpingo-oophorectomy (BSO). Lymphadenectomy prolongs time of surgery and increases the risk of morbidity; where other predictors are available, it may not contribute important supplementary information. 185/247 women with stage I endometrial carcinoma underwent the standard surgery while 62 underwent TAH+BSO. Recurrence and survival were monitored for a mean of 6.5 years and retrospectively reviewed: the rates for groups with and without known lymph node status were alike [13.5% (25/185) recurrence for the former and 12.9% (8/62) for the latter, and 5-year survival rates of 75.7% (140/185) for the former and 74.2 (46/62) for the latter]. Myometrial invasion and histological grade appeared to have been highly accurate predictors without lymph node information. Because information on histological grade is available early and is highly predictive, its use could be incorporated into a revised management algorithm for stage I endometrial cancer which would depend upon ensuring lymphadenectomy for women with low grade histopathology and omitting it for those with high grades on the grounds that no further information is necessary to act appropriately. 相似文献
85.
Sarkar S Flores I Ron Y Derosa C Ozzello L Pestka S 《International journal of oncology》1995,7(1):17-24
Highly aggressive murine B16 melanoma was engineered to secrete IFN-alpha constitutively. Cells expressing IFN-alpha were injected into syngeneic C57BL/6 mice and the mice were monitored for tumor development. Secretion of IFN-alpha by B16 melanoma cells completely abrogated their tumorigenicity in syngeneic mice. LFN-alpha-secreting cells also abrogated the tumorigenicity of IFN-gamma-secreting and TNF-alpha-secreting cells when injected in combination whereas cells secreting either IFN-gamma or TNF-alpha grow progressively in mice when injected alone. Moreover, protected animals developed significant immunity against subsequent challenge with parental cells. Injection of parental cells and IFN-alpha-secreting cells together in a mixed tumor transplantation assay resulted in a significant reduction of tumorigenicity of the parental cells. Histopathological studies of the tissues from the injection site of the mice inoculated with a combination of parental and B16.IFN-alpha cells revealed the existence of a massive cellular infiltrate composed of lymphocytes and granulocytes at an early stage (7-11 days). In the later stages (22 days), no recognizable tumor tissue was detected. Injection of irradiated IFN-alpha-secreting cells in the mice carrying an established tumor completely prevented tumor development in 80% of the treated mice when injection was performed on the same side as the tumors. Injection of irradiated IFN-alpha-secreting cells in the contralateral site showed much less effect on the established tumor. Systemic antitumor effects on the established tumor can be enhanced by using a combination of irradiated IFN-alpha and IFN-gamma secreting cells as a vaccinating inoculum. 相似文献
86.
Acierno R Resnick H Kilpatrick DG Saunders B Best CL 《Journal of anxiety disorders》1999,13(6):814-563
The National Women's Study, a 2-year, three-wave longitudinal investigation, employed a national probability sample of 3,006 adult women to: (a) identify separate risk factors for rape and physical assault, and (b) identify separate risk factors associated with post-rape posttraumatic stress disorder (PTSD) and post-physical assault PTSD. This investigation differed from previous studies in that it prospectively examined risk factors at the multivariate, as opposed to univariate level. Overall, past victimization, young age, and a diagnosis of active PTSD increased women's risk of being raped. By contrast, past victimization, minority ethnic status, active depression, and drug use were associated with increased risk of being physically assaulted. Risk factors for PTSD following rape included a history of depression, alcohol abuse, or experienced injury during the rape. However, risk factors for PTSD following physical assault included only a history of depression and lower education. 相似文献
87.
NGOs in community health insurance schemes: examples from Guatemala and the Philippines 总被引:3,自引:0,他引:3
Ron A 《Social science & medicine (1982)》1999,48(7):939-950
In poor rural communities, access to basic health care is often severely limited by inadequate supply as well as financial barriers to seeking care. National policies may introduce social health insurance, but these are likely to begin with the salaried public and private sector workers while the informal sector population may be the last to be covered. Community initiatives to generate health care financing require a complex development process. This paper covers attempts to develop such schemes in rural populations in Guatemala and the Philippines through non-government organizations and notes the major factors which have contributed to unequal progress in the two schemes. The scheme of the Association por Salud de Barillas (ASSABA) in Guatemala was not sufficiently established as an administrative body at the conceptual stage and there was no clear national policy on health care financing. By the time the necessary action was taken, local conflicts hindered progress. In the Philippines, the ORT Health Plus Scheme (OHPS) was implemented during the period of legislation of a national health insurance act. The appraisal after three years of operation shows that OPHS has made health care affordable and accessible to the target population, composed mainly of low and often unstable income families in rural areas. The major success factors are probably the administrative structure provided by a cooperative and controls in the delivery system and in expenditures, through the salaried primary health care team, referral process and the capitation agreement for hospital-based services. The proliferation of such schemes could benefit from national guidelines, a formal accreditation process and an umbrella organization to provide assistance in design, training and information services, involving government, non-government and academic institutions as an integral part of the development process. 相似文献
88.
89.
Suprathreshold Auditory Cortex Activation Visualized by Intrinsic Signal Optical Imaging 总被引:2,自引:2,他引:0
Bakin Jonathan S.; Kwon Michael C.; Masino Susan A.; Weinberger Norman M.; Frostig Ron D. 《Cerebral cortex (New York, N.Y. : 1991)》1996,6(2):120-130
The suprathreshold tonotopic organization of rat and guineapig auditory cortex was investigated using intrinsic signaloptical imaging through a thinned skull. Optical imaging revealedthat suprathreshold pure sine wave tone stimulation (2540dB) evoked activity over large cortical areas that were tonotopicallyorganized. Three-dimensional surface plots of the activatedareas revealed "patchy" auditory-evoked activity consistingof numerous local peaks and valleys building to a maximum. Subsequentdetailed electrophysiological mapping in the same subjects confirmedthe localization of auditory-evoked activity based on opticalimaging, including responses to a test frequency at corticalloci more than 2 octaves away from the threshold-defined isofrequencycontour. The success of this technique in visualizing auditorycortex functional organization at suprathreshold stimulus levelswill allow for future investigations of auditory cortex frequencyrepresentation. including representational plasticity inducedby a variety of experimental manipulations. 相似文献
90.
Allen L Seligson Brian K Campion Jason W Brown Ron C Terry Renata Kucerova Martina Bienova Marian Hajduch Milos Sovak 《Drug development research》2003,59(3):292-306
Nonsteroidal antiandrogens (AA) cannot be topically used for androgenetic alopecia (AGA) because of systemic resorption. A new class of androgen receptor (AR) suppressors designed for safe topical treatment of AGA was synthesized from (3‐amino‐2‐hydroxy‐2‐methyl‐N‐(4‐nitro‐3‐trifluoromethyl)phenyl) propanamide (BP‐34), to contain perfluoroalkyl moieties. The trifluoromethyl derivative (fluridil) at 10 μM decreased expression of the AR in LNCaP human cells by 95%, its serum half‐life was 6 h; it decomposes hydrolytically to BP‐34 and trifluoroacetic acid. Acute intraperitoneal maximum tolerated dose (MTD) of fluridil in mice is 270–300 mg/kg/d and the subacute MTD is 450 mg/kg/d. The oral LD50 in mice was 2,872 mg/kg in males, 2,232 mg/kg in females, and >2,500 mg/kg in rats. Fluridil solution in isopropanol was not cutaneously absorbed in rabbits, did not sensitize or show any phototoxic or photoallergic effects on guinea pig skin, and demonstrated no skin irritation potential in rabbits and humans. Fluridil solid induced only slight and reversible eye irritancy in rabbits and displayed no cytotoxicity to rabbit corneal fibroblasts in vitro. Fluridil demonstrated no significant mutagenicity potential by Ames method. In a double‐blind study, 43 males with AGA, Norwood grade II to Va, used topical 2% fluridil in isopropanol or the vehicle daily for 12 months. Anagens (growing hairs) increased in the fluridil group from 76% to 89%. All hematological and biochemistry values remained within normal range, including testosterone, which varied but seasonally. No fluridil or its decomposition product (BP‐34) was detected in serum. No adverse side effects were reported. Drug Dev. Res. 59:292–306, 2003. © 2003 Wiley‐Liss, Inc. 相似文献