全文获取类型
收费全文 | 18742篇 |
免费 | 1238篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 216篇 |
儿科学 | 419篇 |
妇产科学 | 345篇 |
基础医学 | 2583篇 |
口腔科学 | 319篇 |
临床医学 | 1623篇 |
内科学 | 4826篇 |
皮肤病学 | 410篇 |
神经病学 | 1618篇 |
特种医学 | 613篇 |
外科学 | 2653篇 |
综合类 | 238篇 |
一般理论 | 8篇 |
预防医学 | 1402篇 |
眼科学 | 412篇 |
药学 | 1121篇 |
中国医学 | 77篇 |
肿瘤学 | 1172篇 |
出版年
2023年 | 132篇 |
2022年 | 330篇 |
2021年 | 545篇 |
2020年 | 306篇 |
2019年 | 447篇 |
2018年 | 515篇 |
2017年 | 342篇 |
2016年 | 364篇 |
2015年 | 449篇 |
2014年 | 619篇 |
2013年 | 840篇 |
2012年 | 1331篇 |
2011年 | 1347篇 |
2010年 | 773篇 |
2009年 | 664篇 |
2008年 | 1125篇 |
2007年 | 1194篇 |
2006年 | 1175篇 |
2005年 | 1105篇 |
2004年 | 1008篇 |
2003年 | 959篇 |
2002年 | 953篇 |
2001年 | 132篇 |
2000年 | 117篇 |
1999年 | 161篇 |
1998年 | 198篇 |
1997年 | 164篇 |
1996年 | 164篇 |
1995年 | 120篇 |
1994年 | 115篇 |
1993年 | 98篇 |
1992年 | 100篇 |
1991年 | 100篇 |
1990年 | 88篇 |
1989年 | 69篇 |
1988年 | 79篇 |
1987年 | 83篇 |
1986年 | 68篇 |
1985年 | 88篇 |
1984年 | 98篇 |
1983年 | 92篇 |
1982年 | 110篇 |
1981年 | 123篇 |
1980年 | 108篇 |
1979年 | 66篇 |
1978年 | 75篇 |
1977年 | 87篇 |
1976年 | 61篇 |
1974年 | 52篇 |
1973年 | 52篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Amy C Y Lo Alvin K H Cheung Victor K L Hung Chung-Man Yeung Qing-Yu He Jen-Fu Chiu Stephen S M Chung Sookja K Chung 《Journal of cerebral blood flow and metabolism》2007,27(8):1496-1509
Previously, we reported that transgenic mice overexpressing endothelin-1 in astrocytes showed more severe neurological deficits and increased infarct after transient focal ischemia. In those studies, we also observed increased level of aldose reductase (AR), the first and rate-limiting enzyme of the polyol pathway, which has been implicated in osmotic and oxidative stress. To further understand the involvement of the polyol pathway, the mice with deletion of enzymes in the polyol pathway, AR, and sorbitol dehydrogenase (SD), which is the second enzyme in this pathway, were challenged with similar cerebral ischemic injury. Deletion of AR-protected animals from severe neurological deficits and large infarct, whereas similar protection was not observed in mice with SD deficiency. Most interestingly, AR(-/-) brains showed lowered expression of transferrin and transferrin receptor with less iron deposition and nitrotyrosine accumulation. The protection against oxidative stress in AR(-/-) brain was also associated with less poly(adenosine diphosphate-ribose) polymerase (PARP) and caspase-3 activation. Pharmacological inhibition of AR by Fidarestat also protected animals against cerebral ischemic injury. These findings are the first to show that AR contributes to iron- and transferrin-related oxidative stress associated with cerebral ischemic injury, suggesting that inhibition of AR but not SD may have therapeutic potential against cerebral ischemic injury. 相似文献
13.
Tushar M Ranchod Daynia E Ballot Alma M Martinez Barbara J Cory Victor A Davies J Colin Partridge 《Suid-Afrikaanse tydskrif vir geneeskunde》2004,94(11):913-916
BACKGROUND: Little is known about parental experience and decision making with regard to premature infants requiring intensive care in developing countries. We undertook this study to characterise parents' experience of physician counselling and their role in making life-support decisions for very low-birth-weight (VLBW) (birth weight < 1 501 g) infants born in South Africa's public-sector neonatal intensive care units (NICUs). METHODS: Parents of surviving VLBW infants treated in three Johannesburg-area public hospitals and attending follow-up clinics in August 2001 were interviewed regarding their experience of perinatal counselling on outcomes (pain, survival, disability), perception of actual and optimal decision making, and satisfaction with NICU communication. RESULTS: Parents of 51 infants were interviewed. Seventy-five per cent of parents reported antenatal counselling by physicians on at least one perinatal topic (severe disability, pain, death, finances or religious/moral considerations). The majority of parents (> 60%) who received counselling thought that these topics had been discussed adequately. Most parents reported that doctors had the primary decision-making role, either without consulting them (41%) or after consulting them (37%). Joint decision making was rare (14%). Parents wanted more input in life-support decisions than they reported being given. CONCLUSION: Counselling is not consistently provided in public-sector hospitals in Johannesburg. Parents of premature infants want a larger share in NICU decision making than they currently experience. Most parents were satisfied with communication later during their infant's hospitalisation. South Africa presents a unique opportunity to study the use of advanced medical technologies in a nation with marked disparities in access to care. 相似文献
14.
15.
The use of 19F spectroscopy and diffusion-weighted MRI to evaluate differences in gene-dependent enzyme prodrug therapies. 总被引:4,自引:0,他引:4
Daniel A Hamstra Kuei C Lee Joseph M Tychewicz Victor D Schepkin Bradford A Moffat Mark Chen Kenneth J Dornfeld Theodore S Lawrence Thomas L Chenevert Brian D Ross Juri T Gelovani Alnawaz Rehemtulla 《Molecular therapy》2004,10(5):916-928
To evaluate noninvasive measures of gene expression and tumor response in a gene-dependent enzyme prodrug therapy (GDEPT), a bifunctional fusion gene between Saccharomyces cerevisiae cytosine deaminase (CD) and Haemophilus influenzae uracil phosphoribosyltransferase (UPRT) was constructed. CD deaminates 5-fluorocytosine (5FC) to 5-fluorouracil (5FU), and UPRT subsequently converts 5FU to fluorouridine monophosphate, and both of these reactions can be monitored noninvasively in vitro and in vivo using 19F magnetic resonance spectroscopy (MRS). Following transient transfection the CD-UPRT fusion protein exhibited both UPRT and CD enzymatic activities as documented by 19F MRS. In addition, an increase in CD activity and thermal stability was witnessed for the fusion protein compared to native CD. Stable expression of CD-UPRT in 9L glioma cells increased both 5FC and 5FU sensitivity in vitro compared to CD-expressing and wild-type 9L cells. Noninvasive 19F MRS of both CD and UPRT gene function in vivo demonstrated that in animals bearing CD-expressing tumors there was limited conversion of 5FC to 5FU with no measurable accumulation of cytotoxic fluorinated nucleotides (F-nucs). In contrast, CD-UPRT-expressing tumors had increased CD gene activity with a threefold higher intratumoral accumulation of 5FU and significant generation of F-nucs. Finally, CD-UPRT yielded increased efficacy in an orthotopic animal model of high-grade glioma. More importantly, early changes in cellular water mobility, which are felt to reflect cellular death, as measured by diffusion-weighted MRI, were predictive of both durable response and increased animal survival. These results demonstrate the increased efficacy of the CD-UPRT GDEPT compared to CD alone both biochemically and in a preclinical model and validate both 19F MRS and diffusion-weighted MRI as tools to assess gene function and therapeutic efficacy. 相似文献
16.
Victor M. Neira Corey Sawchuk Kenneth S. Bonneville Victor Chu Theodore E. Warkentin 《Journal canadien d'anesthésie》2007,54(6):461-466
PURPOSE: To describe the management of severe acute intracardiac thrombosis in a patient who underwent redo multiple valve replacement and valvular repair. The diagnostic features, associated risk factors, and anesthetic management are reviewed. CLINICAL FEATURES: A 67-yr-old woman undergoing redo mitral and aortic mechanical valve replacement and tricuspid annuloplasty under aprotinin prophylaxis exhibited severe refractory hypotension that began immediately after protamine reversal of intraoperative heparin anticoagulation following separation from cardiopulmonary bypass. Intraoperative transesophageal echocardiography revealed severe thrombosis in the right atrium, right ventricle and pulmonary artery. The patient was managed by immediate reheparinization and return to cardiopulmonary bypass (CPB), surgical thrombectomy, and intraoperative administration of recombinant tissue-plasminogen activator. After removal of the thrombi, and separation from CPB, no further protamine was given. One hundred units of blood products and two surgical re-explorations were required to manage subsequent massive postoperative bleeding. Acute heparin-induced thrombocytopenia (HIT) was ruled out using sensitive assays for HIT antibodies. After 16 days in the intensive care unit and 30 more days in hospital, the patient was subsequently transferred to a chronic care facility and succumbed several weeks later. CONCLUSION: Acute intraoperative thrombosis is a rare and potentially fatal complication of cardiac surgery. Intraoperative transesophageal echocardiography was essential for rapid diagnosis in this case. Multiple interacting prothrombotic factors (e.g., aprotinin use, acquired antithrombin deficiency, long pump time, post-protamine status, transfusion of blood components) were likely contributing factors related to this rare complication. 相似文献
17.
Victor W. Acquista M.D. Tom J. Wachtel M.D. Celia I. Gomes M.P.H. Michael Salzillo M.S. Melanie Stockman R.N. 《Journal of community health》1988,13(1):43-52
In an effort to improve Health Risk Appraisals and to induce individuals to change their lifestyles, comprehensive evaluations and counseling sessions were carried out for 476 participants of an experimental preventive care program (1984). Nurse practitioners interviewed participants in their homes and collected information about their lifestyle, medical history, and family history. In addition, physical examinations were performed and blood samples were obtained for laboratory analysis. This information was used to formulate health risk profiles for all participants who were then counseled on how to decrease identified health risks. Interventions included education about health risks and specific programs which were administered to help modify high-risk behaviors. At one year follow-up, significant risk reductions were reported in many areas of increased risk.Victor W. Acquista, M.D., is a Fellow in General Internal Medicine, Rhode Island Hospital. Tom J. Wachtel, M.D., is Director, Medical Primary Care Unit, Rhode Island Hospital, and Assistant Professor of Community Health, Brown University. Celia I. Gomes, M.P.H., is Health Education Coordinator, Blue Cross/Blue Shield of Rhode Island. Michael Salzillo, M.S., is Team Leader, Statistical Analysis Department, Blue Cross/Blue Shield of Rhode Island. Melanie Stockman, R.N., is Director of Ambulatory Nursing, Rhode Island Hospital. 相似文献
18.
19.
20.
Acetylcholinesterase Adaptation to Voluntary Wheel Running is Proportional to the Volume of Activity in Fast, but not Slow, Rat Hindlimb Muscles 总被引:4,自引:0,他引:4
Victor Gisiger Manon Bélisle Phillip F. Gardiner 《The European journal of neuroscience》1994,6(5):673-680
Chronic enhancement of neuromuscular activity by forced exercise training programmes results in selective adaptation of the G4 acetylcholinesterase (AChE) molecular form in hindlimb fast muscles of the rat, with only minor and non-selective AChE changes in the soleus. In order to shed further light on the physiological significance of this G4 adaptation to training, we turned to a voluntary exercise model. The impact of 5 days and 4 weeks of voluntary wheel cage running on AChE molecular forms was examined in four hindlimb fast muscles and the slow-twitch soleus from two rat strains. Inbred Fisher and Sprague– Dawley rats, placed in live-in wheel cages, exercised spontaneously for distances which progressively increased up to an average of ∼3 and 18 km/day, respectively, by the end of week 4. Fast muscles responded to this voluntary activity by massive G4 increases (up to 420%) with almost no changes in A12 , so that by week 4 the tetramer became the main AChE component of these muscles. The additional G4 was composed primarily of amphiphilic molecules, suggesting a membrane-bound state. The G4 content of fast muscles was highly correlated with the distance covered by the rats during the 5 days before they were killed ( r = 0.850-0.879, P < 0.001 in three muscles). The soleus muscle, in turn, responded to wheel cage activity by a marked selective reduction of its asymmetric forms—up to 45% for A12 . This A12 decline, already maximal by day 5 of wheel cage running, showed no relationship with the distance covered. The present results constitute strong new evidence suggesting that the role of AChE in neuromuscular transmission is not limited solely to the rapid inactivation of just-released acetylcholine. 相似文献