全文获取类型
收费全文 | 3259篇 |
免费 | 161篇 |
出版年
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 11篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 40篇 |
2017年 | 26篇 |
2016年 | 57篇 |
2015年 | 87篇 |
2014年 | 104篇 |
2013年 | 126篇 |
2012年 | 293篇 |
2011年 | 326篇 |
2010年 | 110篇 |
2009年 | 84篇 |
2008年 | 242篇 |
2007年 | 204篇 |
2006年 | 259篇 |
2005年 | 216篇 |
2004年 | 224篇 |
2003年 | 188篇 |
2002年 | 184篇 |
2001年 | 119篇 |
2000年 | 146篇 |
1999年 | 75篇 |
1998年 | 19篇 |
1997年 | 13篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 15篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 14篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 13篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1973年 | 4篇 |
1972年 | 4篇 |
排序方式: 共有3420条查询结果,搜索用时 421 毫秒
41.
Lladó Maldonado S. Krull J. Rasch D. Panjan P. Sesay A. M. Marques M. P. C. Szita N. Krull R. 《Bioprocess and biosystems engineering》2020,43(2):359-359
Bioprocess and Biosystems Engineering - Unfortunately, in the “How to Cite as” section, the given and the family name of the author was incorrectly published, the correct name is... 相似文献
42.
Mathias Weber Alexandra R. Wey-Fabrizius Lars Podsiadlowski Alexander Witek Ralph O. Schill László Sugár Holger Herlyn Thomas Hankeln 《Molecular phylogenetics and evolution》2013,66(1):182-189
The metazoan taxon Syndermata (Monogononta, Bdelloidea, Seisonidea, Acanthocephala) comprises species with vastly different lifestyles. The focus of this study is on the phylogeny within the syndermatan subtaxon Acanthocephala (thorny-headed worms, obligate endoparasites). In order to investigate the controversially discussed phylogenetic relationships of acanthocephalan subtaxa we have sequenced the mitochondrial (mt) genomes of Echinorhynchus truttae (Palaeacanthocephala), Paratenuisentis ambiguus (Eoacanthocephala), Macracanthorhynchus hirudinaceus (Archiacanthocephala), and Philodina citrina (Bdelloidea). In doing so, we present the largest molecular phylogenetic dataset so far for this question comprising all major subgroups of Acanthocephala. Alongside with publicly available mt genome data of four additional syndermatans as well as 18 other lophotrochozoan (spiralian) taxa and one outgroup representative, the derived protein-coding sequences were used for Maximum Likelihood as well as Bayesian phylogenetic analyses. We achieved entirely congruent results, whereupon monophyletic Archiacanthocephala represent the sister taxon of a clade comprising Eoacanthocephala and monophyletic Palaeacanthocephala (Echinorhynchida). This topology suggests the secondary loss of lateral sensory organs (sensory pores) within Palaeacanthocephala and is further in line with the emergence of apical sensory organs in the stem lineage of Archiacanthocephala. 相似文献
43.
44.
JA Kiernan 《Biotechnic & histochemistry》2013,88(5-6):203-210
Hexazonium pararosaniline is a valuable reagent that has been used in enzyme activity histochemistry for 50 years. It is an aqueous solution containing the tris-diazonium ion derived from pararosaniline, an aminotriarylmethane dye, and it contains an excess of nitrous acid that was not consumed in the diazotization reaction. Other investigators have found that immersion for 2 min in an acidic (pH 3.5) 0.0015 M hexazonium pararosaniline solution can protect cryostat sections of unfixed animal tissues from the deleterious effects of aqueous reagents such as buffered solutions used in immunohistochemistry, while preserving specific affinities for antibodies. In the present investigation hexazonium pararosaniline protected lymphoid tissue and striated muscle against the damaging effects of water or saline. The same protection was conferred on unfixed sections treated with dilute nitrous or hydrochloric acid in concentrations similar to those in hexazonium pararosaniline solutions. Model tissues (solutions, gels or films containing gelatin and/or bovine albumin) responded predictably to well known cross-linking (formaldehyde) or coagulant (mercuric chloride) fixatives. Hexazonium pararosaniline solutions prevented the dissolution of protein gels in water only after 9 or more days of contact, during which time considerable swelling occurred. It is concluded that there is no evidence for a “fixative” action of hexazonium pararosaniline. The protective effect on frozen sections of unfixed tissue is attributable probably to the low pH of the solution. 相似文献
45.
Montserrat Núñez Stephan Pfister Assumpció Antón Pere Muñoz Stefanie Hellweg Annette Koehler Joan Rieradevall 《Journal of Industrial Ecology》2013,17(1):90-102
The environmental impact of the water consumption of four typical crop rotations grown in Spain, including energy crops, was analyzed and compared against Spanish agricultural and natural reference situations. The life cycle assessment (LCA) methodology was used for the assessment of the potential environmental impact of blue water (withdrawal from water bodies) and green water (uptake of soil moisture) consumption. The latter has so far been disregarded in LCA. To account for green water, two approaches have been applied: the first accounts for the difference in green water demand of the crops and a reference situation. The second is a green water scarcity index, which measures the fraction of the soil‐water plant consumption to the available green water. Our results show that, if the aim is to minimize the environmental impacts of water consumption, the energy crop rotations assessed in this study were most suitable in basins in the northeast of Spain. In contrast, the energy crops grown in basins in the southeast of Spain were associated with the greatest environmental impacts. Further research into the integration of quantitative green water assessment in LCA is crucial in studies of systems with a high dependence on green water resources. 相似文献
46.
Lászió Puskás József Czombos Sándor Bottka 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):967-968
Abstract Phosphoramidite derivative of 1,4-diamino antraquinone was synthesized, characterized, and incorporated into oligonucleotides. Intercalative interaction between the dye and the nucleic acid was confirmed by CD spectroscopy. 相似文献
47.
48.
Anita Rózsás Judit Berta Lívia Rojkó László Z. Horváth Magdolna Keszthelyi István Kenessey Viktória László Walter Berger Michael Grusch Mir Alireza Hoda Szilvia T?r?k Walter Klepetko Ferenc Rényi-Vámos Balázs Heged?s Balázs D?me József Tóvári 《PloS one》2013,8(10)
Recombinant human erythropoietins (rHuEPOs) are used to treat cancer-related anemia. Recent preclinical studies and clinical trials, however, have raised concerns about the potential tumor-promoting effects of these drugs. Because the clinical significance of erythropoietin receptor (EPOR) signaling in human non-small cell lung cancer (NSCLC) also remains controversial, our aim was to study whether EPO treatment modifies tumor growth and if EPOR expression has an impact on the clinical behavior of this malignancy. A total of 43 patients with stage III–IV adenocarcinoma (ADC) and complete clinicopathological data were included. EPOR expression in human ADC samples and cell lines was measured by quantitative real-time polymerase chain reaction. Effects of exogenous rHuEPOα were studied on human lung ADC cell lines in vitro. In vivo growth of human ADC xenografts treated with rHuEPOα with or without chemotherapy was also assessed. In vivo tumor and endothelial cell (EC) proliferation was determined by 5-bromo-2’-deoxy-uridine (BrdU) incorporation and immunofluorescent labeling. Although EPOR mRNA was expressed in all of the three investigated ADC cell lines, rHuEPOα treatment (either alone or in combination with gemcitabine) did not alter ADC cell proliferation in vitro. However, rHuEPOα significantly decreased tumor cell proliferation and growth of human H1975 lung ADC xenografts. At the same time, rHuEPOα treatment of H1975 tumors resulted in accelerated tumor endothelial cell proliferation. Moreover, in patients with advanced stage lung ADC, high intratumoral EPOR mRNA levels were associated with significantly increased overall survival. This study reveals high EPOR level as a potential novel positive prognostic marker in human lung ADC. 相似文献
49.
Cristina Teixidó Rosó Marés Miguel Aracil Santiago Ramón y Cajal Javier Hernández-Losa 《PloS one》2013,8(1)
Elisidepsin (elisidepsin trifluoroacetate, Irvalec®, PM02734) is a new synthetic depsipeptide, a result of the PharmaMar Development Program that seeks synthetic products of marine origin-derived compounds. Elisidepsin is a drug with antiproliferative activity in a wide range of tumors. In the present work we studied and characterized the mechanisms associated with sensitivity and resistance to elisidepsin treatment in a broad panel of tumor cell lines from breast and pancreas carcinomas, focusing on different factors involved in epithelial-mesenchymal transition (EMT) and the use of HER family receptors in predicting the in vitro drug response. Interestingly, we observed that the basal protein expression levels of EMT markers show a significant correlation with cell viability in response to elisidepsin treatment in a panel of 12 different breast and pancreatic cancer cell lines. In addition, we generated three elisidepsin treatment-resistant cell lines (MCF-7, HPAC and AsPC-1) and analyzed the pattern of expression of different EMT markers in these cells, confirming that acquired resistance to elisidepsin is associated with a switch to the EMT state. Furthermore, a direct correlation between basal HER3 expression and sensitivity to elisidepsin was observed; moreover, modulation of HER3 expression levels in different cancer cell lines alter their sensitivities to the drug, making them more resistant when HER3 expression is downregulated by a HER3-specific short hairpin RNA and more sensitive when the receptor is overexpressed. These results show that HER3 expression is an important marker of sensitivity to elisidepsin treatment. 相似文献
50.
Erzsébet Fehér Éva Pongor Károly Altdorfer László Kóbori Gabriella Lengyel 《Cell and tissue research》2013,354(2):543-550
Bidirectional interaction between immune and nervous systems is considered an important biological process in health and disease. However, little is known about the mechanisms involved in their interaction in the human liver. This study examines the distribution of intrahepatic NPY, SP immunoreactive (IR) nerve fibers and their antomical relationship with immunocells containing tumor necrosis factor-α (TNF-α) and nuclear factor κB (NF-κB) in patients with autoimmune hepatitis. Liver specimens were obtained from control liver and autoimmune hepatitis patients. The immunoreactivity was determined by immunohisto- and immunocytochemistry and confocal laser microscopy. In hepatitis, the number of NPY-IR and SP-IR nerve fibers increased significantly. These IR nerve fibers were in very close contact with the lymphocytes. In healthy controls, no NPY-IR, SP-IR or NF-κB IR lymphocytes and only a few TNF-α positive cells, were observed. In hepatitis, some of the lymphocytes showed immunoreactivity for SP and NPY in the portal area. Fluorescent double-labeled immunostaining revealed that in these cells NPY did not colocalize with TNF-α or NF-κB. However, some of the SP fluorescence-positive immune cells exhibited immunostaining for p65 of NF-κB, where their labeling was detected in the nuclei. Under the electronmicroscope, these cells could be identified (lymphocytes, plasmacells and mast cells). The gap between the IR nerve fibers and immunocells was 1 μm or even less. Overexpression of SP in lymphocytes may amplify local inflammation, while NPY may contribute to liver homeostasis in hepatitis. Neural immunomodulation (SP antagonists and NPY) might be a novel therapeutic concept in the management of liver inflammation. 相似文献