全文获取类型
收费全文 | 808469篇 |
免费 | 86601篇 |
国内免费 | 421篇 |
专业分类
895491篇 |
出版年
2016年 | 9067篇 |
2015年 | 13768篇 |
2014年 | 15742篇 |
2013年 | 21719篇 |
2012年 | 24951篇 |
2011年 | 24855篇 |
2010年 | 16840篇 |
2009年 | 15870篇 |
2008年 | 22697篇 |
2007年 | 23289篇 |
2006年 | 21773篇 |
2005年 | 21025篇 |
2004年 | 20811篇 |
2003年 | 20160篇 |
2002年 | 19524篇 |
2001年 | 34425篇 |
2000年 | 34817篇 |
1999年 | 28164篇 |
1998年 | 10917篇 |
1997年 | 11486篇 |
1996年 | 11023篇 |
1995年 | 10422篇 |
1994年 | 10275篇 |
1993年 | 10094篇 |
1992年 | 23661篇 |
1991年 | 22919篇 |
1990年 | 22545篇 |
1989年 | 21859篇 |
1988年 | 20119篇 |
1987年 | 19790篇 |
1986年 | 18150篇 |
1985年 | 18238篇 |
1984年 | 15164篇 |
1983年 | 13250篇 |
1982年 | 10611篇 |
1981年 | 9456篇 |
1980年 | 9012篇 |
1979年 | 14575篇 |
1978年 | 11743篇 |
1977年 | 10599篇 |
1976年 | 9992篇 |
1975年 | 10827篇 |
1974年 | 11653篇 |
1973年 | 11438篇 |
1972年 | 10232篇 |
1971年 | 9484篇 |
1970年 | 8117篇 |
1969年 | 7674篇 |
1968年 | 6849篇 |
1967年 | 6182篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
Wei Sun Yoon-Dong Park Janyce A. Sugui Annette Fothergill Noel Southall Paul Shinn John C. McKew Kyung J. Kwon-Chung Wei Zheng Peter R. Williamson 《PloS one》2013,8(8)
A recent large outbreak of fungal infections by Exserohilum rostratum from contaminated compounding solutions has highlighted the need to rapidly screen available pharmaceuticals that could be useful in therapy. The present study utilized two newly-developed high throughput assays to screen approved drugs and pharmaceutically active compounds for identification of potential antifungal agents. Several known drugs were found that have potent effects against E. rostratum including the triazole antifungal posaconazole. Posaconazole is likely to be effective against infections involving septic joints and may provide an alternative for refractory central nervous system infections. The anti-E. rostratum activities of several other drugs including bithionol (an anti-parasitic drug), tacrolimus (an immunosuppressive agent) and floxuridine (an antimetabolite) were also identified from the drug repurposing screens. In addition, activities of other potential antifungal agents against E. rostratum were excluded, which may avoid unnecessary therapeutic trials and reveals the limited therapeutic alternatives for this outbreak. In summary, this study has demonstrated that drug repurposing screens can be quickly conducted within a useful time-frame. This would allow clinical implementation of identified alternative therapeutics and should be considered as part of the initial public health response to new outbreaks or rapidly-emerging microbial pathogens. 相似文献
922.
Robine J. Rischen K. Hero Breuning Ewald M. Bronkhorst Anne Marie Kuijpers-Jagtman 《PloS one》2013,8(11)
Background
Traditionally, dental models, facial and intra-oral photographs and a set of two-dimensional radiographs are used for orthodontic diagnosis and treatment planning. As evidence is lacking, the discussion is ongoing which specific records are needed for the process of making an orthodontic treatment plan.Objective
To estimate the contribution and importance of different diagnostic records for making an orthodontic diagnosis and treatment plan.Data sources
An electronic search in PubMed (1948–July 2012), EMBASE Excerpta Medica (1980–July 2012), CINAHL (1982–July 2012), Web of Science (1945–July 2012), Scopus (1996–July 2012), and Cochrane Library (1993–July 2012) was performed. Additionally, a hand search of the reference lists of included studies was performed to identify potentially eligible studies. There was no language restriction.Study selection
The patient, intervention, comparator, outcome (PICO) question formulated for this study was as follows: for patients who need orthodontic treatment (P), will the use of record set X (I) compared with record set Y (C) change the treatment plan (O)? Only primary publications were included.Data extraction
Independent extraction of data and quality assessment was performed by two observers.Results
Of the 1041 publications retrieved, 17 met the inclusion criteria. Of these, 4 studies were of high quality. Because of the limited number of high quality studies and the differences in study designs, patient characteristics, and reference standard or index test, a meta-analysis was not possible.Conclusion
Cephalograms are not routinely needed for orthodontic treatment planning in Class II malocclusions, digital models can be used to replace plaster casts, and cone-beam computed tomography radiographs can be indicated for impacted canines. Based on the findings of this review, the minimum record set required for orthodontic diagnosis and treatment planning could not be defined.Systematic review registration number
CRD42012002365 相似文献923.
924.
A comparison between two different harvest systems for Miscanthus x giganteus crop (direct cut/chip and mow/bale) in terms of the net energy delivered to an end user, and the various energy costs and energy yields associated with each system was conducted. Only minor differences in terms of energy consumption were observed between the two harvest systems when all phases of the harvesting chain had been taken into account. Chip harvesting consumed 0.11 GJ?t?1 compared with 0.13 GJ?t?1 for bale harvesting. Chip transportation was considerably more expensive than bale transportation for a set distance of 50 km (0.18 and 0.11 GJ?t?1 for chip and bale, respectively). Despite this, higher overall net energy yield was achieved by direct cutting and chipping the material. This was due to the higher proportion of harvestable energy lost in the field as a result of the use of a mowing/baling system. The overall net energy delivered in terms of harvestable material by the direct cut and chip system was 12.45 GJ?t–1 compared with 11.78 GJ?t?1 by the mow and bale system, making direct cut the more efficient system even up to a transport distance of 400 km. A sensitivity analysis indicated that the choice of transport system becomes more important for energy efficiency as transport distance increases. 相似文献
925.
Sebastian M. Mboma Rein M. G. J. Houben Judith R. Glynn Lifted Sichali Francis Drobniewski James Mpunga Paul E. M. Fine Neil French Amelia C. Crampin 《PloS one》2013,8(3)
Background
The rise in tuberculosis (TB) incidence following generalized HIV epidemics can overwhelm TB control programmes in resource-limited settings, sometimes accompanied by rising rates of drug resistance. This has led to claims that DOTS-based TB control has failed in such settings. However, few studies have described the effect of a sustained and well-supported DOTS programme on TB incidence and drug resistance over a long period. We present long-term trends in incidence and drug resistance in rural Malawi.Methods
Karonga District in northern Malawi has an adult HIV prevalence of ∼10%. A research group, the Karonga Prevention Study, collaborates with the National Tuberculosis Programme to support core TB control activities. Bacteriological, demographic and clinical (including HIV status) information from all patients starting TB treatment in the District have been recorded since 1988. During that period isolates from each culture-positive TB patient were exported for drug sensitivity testing. Antiretroviral therapy (ART) has been widely available since 2005.Results
Incidence of new smear-positive adult TB peaked at 124/100,000/year in the mid-90s, but has since fallen to 87/100,000/year. Drug sensitivity information was available for 95% (3132/3307) of all culture-positive cases. Initial resistance to isoniazid was around 6% with no evidence of an increase. Fewer than 1% of episodes involved a multi-drug resistant strain.Discussion
In this setting with a generalised HIV epidemic and medium TB burden, a well-supported DOTS programme enhanced by routine culture and drug sensitivity testing may well have reduced TB incidence and maintained drug resistance at low levels. 相似文献926.
Fabien Dépis Eric Hatterer Romain Ballet Bruno Daubeuf Laura Cons Sophie Glatt Walter Reith Marie Kosco-Vilbois Yann Dean 《MABS-AUSTIN》2013,5(4):555-564
Fc-modified anti-human CD3ε monoclonal antibodies (mAbs) are in clinical development for the treatment of autoimmune diseases. These next generation mAbs have completed clinical trials in patients with type-1 diabetes and inflammatory bowel disease demonstrating a narrow therapeutic window. Lowered doses are ineffective, yet higher pharmacologically-active doses cause an undesirable level of adverse events. Thus, there is a critical need for a return to bench research to explore ways of improving clinical outcomes. Indeed, we recently reported that a short course of treatment affords synergy, providing long-term disease amelioration when combining anti-mouse CD3 and anti-mouse tumor necrosis factor mAbs in experimental arthritis. Such strategies may widen the window between risk and benefit; however, to more accurately assess experimentally the biology and pharmacology, reagents that mimic the current development candidates were required. Consequently, we engineered an Fc-modified anti-mouse CD3ε mAb, 2C11-Novi. Here, we report the functional characterization of 2C11-Novi demonstrating that it does not bind FcγR in vitro and elicits little cytokine release in vivo, while maintaining classical pharmacodynamic effects (CD3-TCR downregulation and T cell killing). Furthermore, we observed that oral administration of 2C11-Novi ameliorated progression of remitting-relapsing experimental autoimmune encephalitis in mice, significantly reducing the primary acute and subsequent relapse phase of the disease. With innovative approaches validated in two experimental models of human disease, 2C11-Novi represents a meaningful tool to conduct further mechanistic studies aiming at exploiting the immunoregulatory properties of Fc-modified anti-CD3 therapies via combination therapy using parenteral or oral routes of administration. 相似文献
927.
E. De Pauw E. Marafante J. Riego C. Leuratti 《Nucleosides, nucleotides & nucleic acids》2013,32(3):361-364
Abstract The identification and quantitation of DNA adducts formed by reaction of genotoxic chemicals with DNA may provide direct evidence of exposure t o mutagens and carcinogens and may make possible a beginning of risk estimation based on Molecular Dosimetry approach. 相似文献
928.
Uric acid, despite being a major antioxidant in the human plasma, both correlates and predicts development of obesity, hypertension, and cardiovascular disease, conditions associated with oxidative stress. While one explanation for this paradox could be that a rise in uric acid represents an attempted protective response by the host, we review the evidence that uric acid may function either as an antioxidant (primarily in plasma) or pro-oxidant (primarily within the cell). We suggest that it is the pro-oxidative effects of uric acid that occur in cardiovascular disease and may have a contributory role in the pathogenesis of these conditions. 相似文献
929.
André B. P. van Kuilenburg Heinz-Josef Klumpen Anneke M. Westermann Lida Zoetekouw Piet J. M. Bakker Henk-Jan Guchelaar 《Nucleosides, nucleotides & nucleic acids》2013,32(6-7):726-732
Dihydropyrimidine dehydrogenase (DPD) plays a pivotal role in the metabolism of 5-fluorouracil (5FU). In patients treated with capecitabine or 5FU combined with other chemotherapeutic drugs, DPD activity in peripheral blood mononuclear cells was increased in patients experiencing grade I/II neutropenia. In contrast, decreased DPD activity proved to be associated with grade I/II dermatological toxicity, including hand-foot syndrome. Thus, patients with a low-normal or high-normal DPD activity proved to be at risk of developing mild toxicity upon treatment with 5FU-based chemotherapy, demonstrating the important role of DPD in the etiology of toxicity associated with 5FU and the catabolites of 5FU. 相似文献
930.
Erica G. Tierney Garry P. Duffy Sally-Ann Cryan Caroline M. Curtin Fergal J. O’Brien 《Organogenesis》2013,9(1):22-25
One solution to the shortage of human organs available for transplantation envisions growing new organs in situ. This can be accomplished by transplantation of developing organ anlagen/primordia. Allotransplantation of embryonic day 15 metanephroi into the omentum of adult hosts is followed by differentiation, growth, vascularization and function of the implants. Here we show that survival of rats with all native renal mass removed can be increased by prior metanephros transplantation and ureteroureterostomy. Excretion of urine formed by metanephroi is prerequisite for enhanced survival. This is the first demonstration that life can be extended following de novo renal organogenesis. 相似文献