全文获取类型
收费全文 | 6721篇 |
免费 | 526篇 |
国内免费 | 1篇 |
出版年
2023年 | 39篇 |
2022年 | 98篇 |
2021年 | 192篇 |
2020年 | 118篇 |
2019年 | 132篇 |
2018年 | 155篇 |
2017年 | 124篇 |
2016年 | 218篇 |
2015年 | 394篇 |
2014年 | 421篇 |
2013年 | 494篇 |
2012年 | 624篇 |
2011年 | 559篇 |
2010年 | 367篇 |
2009年 | 353篇 |
2008年 | 456篇 |
2007年 | 416篇 |
2006年 | 358篇 |
2005年 | 300篇 |
2004年 | 266篇 |
2003年 | 288篇 |
2002年 | 258篇 |
2001年 | 50篇 |
2000年 | 36篇 |
1999年 | 65篇 |
1998年 | 50篇 |
1997年 | 46篇 |
1996年 | 27篇 |
1995年 | 35篇 |
1994年 | 36篇 |
1993年 | 31篇 |
1992年 | 28篇 |
1991年 | 17篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 19篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 5篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1974年 | 9篇 |
1973年 | 5篇 |
1970年 | 5篇 |
1969年 | 8篇 |
排序方式: 共有7248条查询结果,搜索用时 234 毫秒
901.
Houses that underwent water damages are often responsible for heath problems of the occupants. Since there is no universally used protocol for the analysis, we wanted to verify the usefulness of surface sampling versus air sampling for the evaluation of mold diversity in problematic houses and the value of the number of visible mold growth zones to predict air quality. Seventeen houses were sampled for culturable molds in the air and on the surfaces showing contamination. We compared the mold taxa found in the air and on the surfaces and verified the correlation between the number of moldy surfaces and airbone mold concentration. This study demonstrated that, surprisingly, some of the so called wet spore molds (e.g. Stachybotrys) were found more often from air than surface samples whereas, some dry spore molds (e.g. Asp. fumigatus) was more easily isolated from surface samples. There was a good correlation between the number of visible mold growth zones and the concentration of airborne molds. We conclude that air and surface sampling are necessary to evaluate mold diversity in problematic houses and that the number of mold growth zones is a good predictor of airborne mold concentration. 相似文献
902.
Knowledge of the target cells is fundamental to maximise efficiency in attempts at immortalisation of specific cell types. It is also important to optimise the primary cell culture system to promote the survival of the target cell population. Other important factors that may influence the success in obtaining immortalised cells include the toxicity and efficiency of the immortalisation procedure. These can be assessed experimentally and if necessary appropriate techniques can be employed to purify the target cells. When cell lines have been established it is vital to assess them at an early stage for desired scientific and practical features as well as determining their stability and life-span. Furthermore, early characterisation of cell line authenticity (e.g. genetic characters, species of origin) and quality control testing will avoid wasted time and resources should contamination with micro-organisms or another cell line occur. Establishing a programme of immortalisation is a serious undertaking that should only be considered when there are no candidate continuous cell lines available. However, new approaches to modify the biology of cells to give extended life-span, whilst retaining the characteristics of differentiated cells in vivo, will hopefully provide valuable new substrates for in vitro toxicology. 相似文献
903.
904.
Raoul Santiago Johanna Ortiz Jimenez Reza Forghani Nikesh Muthukrishnan Olivier Del Corpo Shairabi Karthigesu Muhammad Yahya Haider Caroline Reinhold Sarit Assouline 《Translational oncology》2021,14(10)
Biomarkers which can identify Diffuse Large B-Cell Lymphoma (DLBCL) likely to be refractory to first-line therapy are essential for selecting this population prior to therapy initiation to offer alternate therapeutic options that can improve prognosis. We tested the ability of a CT-based radiomics approach with machine learning to predict Primary Treatment Failure (PTF)-DLBCL from initial imaging evaluation. Twenty-six refractory patients were matched to 26 non-refractory patients, yielding 180 lymph nodes for analysis. Manual 3D delineation of the total node volume was performed by two independent readers to test the reproducibility. Then, 1218 hand-crafted radiomic features were extracted. The Random Forests machine learning approach was used as a classifier for constructing the prediction models. Seventy percent of the nodes were randomly assigned to a training set and the remaining 30% were assigned to an independent test set. The final model was tested on the dataset from the 2 readers, showing a mean accuracy, sensitivity and specificity of 73%, 62% and 82%, respectively, for distinguishing between refractory and non-refractory patients. The area under the receiver operating characteristic curve (AUC) was 0.83 and 0.79 for the two readers. We conclude that machine learning CT-based radiomics analysis is able to identify a priori PTF-DLBCL with a good accuracy. 相似文献
905.
Christelle Boileau Johanne Martel-Pelletier Judith Caron Philippe Msika Georges B Guillou Caroline Baudouin Jean-Pierre Pelletier 《Arthritis research & therapy》2009,11(2):R41-9
Introduction
The aims of this study were, first, to investigate the in vivo effects of treatment with avocado/soybean unsaponifiables on the development of osteoarthritic structural changes in the anterior cruciate ligament dog model and, second, to explore their mode of action. 相似文献906.
Caroline L. Willis John H. Cummings Graham Neale Glenn R. Gibson 《Current microbiology》1997,35(5):294-298
In contrast to other anaerobic ecosystems, such as marine and estuarine sediments, there is a lack of information on the
nutritional requirements of human gut sulfate-reducing bacteria (SRB). Various substrates stimulated sulfate reduction in
mixed culture, including short-chain fatty acids and other organic acids, alcohols, and amino acids (but not sugars or aromatic
compounds). However, the use of sodium molybdate as a specific inhibitor of sulfate reduction caused an accumulation of ethanol
and malonate only, and reduced the rate of utilization of lactate. This indicates the importance of these electron donors
for sulfate reduction. Since ethanol and lactate are primarily utilized by members of the Desulfovibrio genus, the results suggest a physiologically important role for this group. Experiments with two strains of Desulfovibrio desulfuricans isolated from human feces demonstrated that both were able to reduce sulfite, thiosulfate or nitrate in the absence of sulfate.
In addition, one strain (DsvUC1) was able to grow by fermentative metabolism, although the second strain (DsvFD1) showed more
restricted fermentative growth. The data indicate that desulfovibrios are ecologically the most significant group of SRB in
the human colon, and that colonic isolates belonging to this genus are versatile, in terms of both the electron acceptors
and donors that they are able to utilize.
Received: 24 March 1997 / Accepted: 10 June 1997 相似文献
907.
908.
Mischa R. Müller Kenneth Saunders Christopher Grace Macy Jin Nicole Piche-Nicholas John Steven Ronan O’Dwyer Leeying Wu Lam Khetemenee Yulia Vugmeyster Timothy P. Hickling Lioudmila Tchistiakova Stephane Olland Davinder Gill Allan Jensen Caroline J. Barelle 《MABS-AUSTIN》2012,4(6):673-685
Advances in recombinant antibody technology and protein engineering have provided the opportunity to reduce antibodies to their smallest binding domain components and have concomitantly driven the requirement for devising strategies to increase serum half-life to optimise drug exposure, thereby increasing therapeutic efficacy. In this study, we adopted an immunization route to raise picomolar affinity shark immunoglobulin new antigen receptors (IgNARs) to target human serum albumin (HSA). From our model shark species, Squalus acanthias, a phage display library encompassing the variable binding domain of IgNAR (VNAR) was constructed, screened against target, and positive clones were characterized for affinity and specificity. N-terminal and C-terminal molecular fusions of our lead hit in complex with a naïve VNAR domain were expressed, purified and exhibited the retention of high affinity binding to HSA, but also cross-selectivity to mouse, rat and monkey serum albumin both in vitro and in vivo. Furthermore, the naïve VNAR had enhanced pharmacokinetic (PK) characteristics in both N- and C-terminal orientations and when tested as a three domain construct with naïve VNAR flanking the HSA binding domain at both the N and C termini. Molecules derived from this platform technology also demonstrated the potential for clinical utility by being available via the subcutaneous route of delivery. This study thus demonstrates the first in vivo functional efficacy of a VNAR binding domain with the ability to enhance PK properties and support delivery of multifunctional therapies. 相似文献
909.
Rates of excretion of NH4+ urea and dissolved primary amines(DPA) by Acartia tonsa were measured over two 24-h periods inestuarine mesocosms. Animals ( 相似文献
910.