全文获取类型
收费全文 | 2566篇 |
免费 | 127篇 |
国内免费 | 4篇 |
出版年
2023年 | 26篇 |
2022年 | 20篇 |
2021年 | 75篇 |
2020年 | 48篇 |
2019年 | 56篇 |
2018年 | 94篇 |
2017年 | 62篇 |
2016年 | 81篇 |
2015年 | 118篇 |
2014年 | 148篇 |
2013年 | 193篇 |
2012年 | 200篇 |
2011年 | 179篇 |
2010年 | 119篇 |
2009年 | 118篇 |
2008年 | 119篇 |
2007年 | 103篇 |
2006年 | 100篇 |
2005年 | 90篇 |
2004年 | 69篇 |
2003年 | 69篇 |
2002年 | 70篇 |
2001年 | 53篇 |
2000年 | 44篇 |
1999年 | 36篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 21篇 |
1991年 | 23篇 |
1990年 | 16篇 |
1989年 | 28篇 |
1988年 | 24篇 |
1987年 | 24篇 |
1986年 | 19篇 |
1985年 | 21篇 |
1984年 | 21篇 |
1983年 | 7篇 |
1982年 | 15篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 19篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1970年 | 5篇 |
排序方式: 共有2697条查询结果,搜索用时 15 毫秒
991.
As an adaptive mechanism, hypocotyl dormancy delays emergence of functional leaf until favorable season of growth in Podophyllum hexandrum, an endangered medicinal plant of the western Himalayas. However, upon exposure of the freshly germinated seedlings to favorable
temperature (25°C), functional leaves emerged within 20 days. Therefore, we examined regulation mechanisms of growth and development
of this alpine plant by temperature under laboratory conditions. The seedlings were exposed to (1) 25°C (temperature prevailing
at the time of maximum vegetative growth), (2) 4°C (mean temperature at the onset of winter in its natural habitat), and (3)
10°C (an intermediate temperature). Slackened growth at 4°C was followed by senescence of aerial parts and quiescence of roots
and predetermined leaf primordia. Rapid development of leaf primordia at 25°C was associated with increased starch hydrolysis.
This was evident from higher α-amylase activity and reducing sugars. These parameters decreased on sudden exposure to 4°C.
In contrast, the roots (perennating organs) showed a slight increase (1.36-fold) in α-amylase activity. Growth and development
in seedlings growing at 10°C (temperature less adverse than 4°C) were comparatively faster. The content of reducing sugars
and α-amylase activity were also higher in all the seedling parts at 10°C as compared to 4°C. This indicated larger requirements
for sugar by the seedlings at 10°C. Irrespective of temperature, maximum changes in nitrate and nitrate reductase occurred
during the initial 10 days, i.e., when the readily available form of sugars (reducing sugar) was highest. This indicated that
a temperature-dependent availability of carbon, but not temperature itself, was an important regulator of uptake and reduction
of nitrogen.
IHBT Publication number 508a. 相似文献
992.
Neeraj Kumar Saini Monika Sharma Amita Chandolia Rashmi Pasricha Vani Brahmachari Mridula Bose 《BMC microbiology》2008,8(1):200
Background
The mce4 operon is one of the four homologues of mammalian cell entry (mce) operons of Mycobacterium tuberculosis. The mce4A (Rv3499c) gene within this operon is homologous to mce1A (Rv0169), that has a role in host cell invasion by M. tuberculosis. Our earlier reports show that mce4 operon is expressed during the stationary phase of growth of the bacillus in culture and during the course of infection in mammalian hosts. M. tuberculosis carrying mutation in mce4 operon shows growth defect and reduced survival in infected mice. However, the intracellular localization of Mce4A protein and its direct role in cell entry or survival of the bacillus has not been demonstrated so far. 相似文献993.
Harsha HC Jimeno A Molina H Mihalas AB Goggins MG Hruban RH Schulick RD Kamath U Maitra A Hidalgo M Pandey A 《Journal of proteome research》2008,7(11):4651-4658
Pancreatic cancer is one of the most fatal among all solid malignancies. Targeted therapeutic approaches have the potential to transform cancer therapy as exemplified by the success of several tyrosine kinase inhibitors. Prompted by this, comprehensive profiling of tyrosine kinases and their substrates was carried out using a panel of low passage pancreatic cancer cell lines. One of the pancreatic cancer cell lines, P196, which showed dramatic upregulation of tyrosine kinase activity as compared to non-neoplastic cells, was systematically studied using a quantitative proteomic approach called stable isotope labeling with amino acids in cell culture (SILAC). A careful analysis of activated tyrosine kinase pathways revealed aberrant activation of epidermal growth factor receptor pathway in this cell line. Mouse xenograft based studies using EGFR inhibitor erlotinib confirmed EGFR pathway to be responsible for proliferation in these tumors. By a systematic study across low passage pancreatic cancer cell lines and mice carrying pancreatic cancer xenografts, we have demonstrated activated epidermal growth factor receptor as an attractive candidate for targeted therapy in a subset of pancreatic cancers. Further, we propose immunohistochemical labeling of activated EGFR (pEGFR (1068)) as an efficient screening tool to select patients who are more likely to respond to EGFR inhibitors. 相似文献
994.
Clinical proteomics is an emerging field that deals with the use of proteomic technologies for medical applications. With a major objective of identifying proteins involved in pathological processes and as potential biomarkers, this field is already gaining momentum. Consequently, clinical proteomics data are being generated at a rapid pace, although mechanisms of sharing such data with the biomedical community lag far behind. Most of these data are either provided as supplementary information through journal web sites or directly made available by the authors through their own web resources. Integration of these data within a single resource that displays information in the context of individual proteins is likely to enhance the use of proteomic data in biomedical research. Human Proteinpedia is one such portal that unifies human proteomic data under a single banner. The goal of this resource is to ultimately capture and integrate all proteomic data obtained from individual studies on normal and diseased tissues. We anticipate that harnessing of these data will help prioritize experiments related to protein targets and also permit meta-analysis to uncover molecular signatures of disease. Finally, we encourage all biomedical investigators to maximize dissemination of their valuable proteomic data to rest of the community by active participation in existing repositories such as Human Proteinpedia. 相似文献
995.
996.
Raghothama Chaerkady Paul J. Thuluvath Min-Sik Kim Anuradha Nalli Perumal Vivekanandan Jessica Simmers Michael Torbenson Akhilesh Pandey 《Clinical proteomics》2008,4(3-4):137-155
Introduction
Quantitative proteomics using tandem mass spectrometry is an attractive approach for identification of potential cancer biomarkers. Fractionation of complex tissue samples into subproteomes prior to mass spectrometric analyses increases the likelihood of identifying cancer-specific proteins that might be present in low abundance. In this regard, glycosylated proteins are an interesting class of proteins that are already established as biomarkers for several cancers.Materials and Methods
In this study, we carried out proteomic profiling of tumor and adjacent non-cancer liver tissues from hepatocellular carcinoma (HCC) patients. Glycoprotein enrichment from liver samples using lectin affinity chromatography and subsequent 18O/16O labeling of peptides allowed us to obtain relative abundance levels of lectin-bound proteins. As a complementary approach, we also examined the relative expression of proteins in HCC without glycoprotein enrichment. Lectin affinity enrichment was found to be advantageous to quantitate several interesting proteins, which were not detected in the whole proteome screening approach. We identified and quantitated over 200 proteins from the lectin-based approach. Interesting among these were fetuin, cysteine-rich protein 1, serpin peptidase inhibitor, leucine-rich alpha-2-glycoprotein 1, melanoma cell adhesion molecule, and heparan sulfate proteoglycan-2. Using lectin affinity followed by PNGase F digestion coupled to 18O labeling, we identified 34 glycosylation sites with consensus sequence N-X-T/S. Western blotting and immunohistochemical staining were carried out for several proteins to confirm mass spectrometry results.Conclusion
This study indicates that quantitative proteomic profiling of tumor tissue versus non-cancerous tissue is a promising approach for the identification of potential biomarkers for HCC. 相似文献997.
Three families of proteinase inhibitors, namely, serine, cysteine (thiol) and aspartic (carboxyl) were examined for their
inhibitory effects on growth and development of Indian alfalfa weevil (Coleoptera: Curculionidae). Proteinase inhibitors are
considered as a part of alternate strategy to control the herbivorous insect as they inhibit the digestive enzymes of the
insects. Larval leaf feeding, survival, pupation and adult emergence were significantly decreased by pHMB, (p-hydroxy-mercuribenzoic acid), cystatin and E-64 (trans-epoxysuccinyl-l-leucylamido-(4guanidino)-butane) belonging to cysteine class of proteinases, at a concentration of 0.1 and 0.5%. Serine and
aspartic classes of inhibitors have low detrimental effects on larvae. The results demonstrate the inhibitory response of
specific proteinase inhibitors on alfalfa weevil larval leaf feeding, survival, pupation and adult emergence. Weevil resistant
species, namely, Medicago scutellata showed high level of leaf consumption under forced feeding in vivo bioassay indicated the presence of resistance factors
other than proteinase inhibitors. 相似文献
998.
999.
Sharrel Rebello Mohandas Anju Embalil Mathachan Aneesh Raveendran Sindhu Parameswaran Binod Ashok Pandey 《Reviews in Environmental Science and Biotechnology》2017,16(3):381-394
The wide utility and catalytic efficiency of microbial pectinase in various industries has greatly increased its global demand. Among the natural sources of pectinases, microbial pectinases are used frequently for its ease of production and unique physicochemical properties. Yet similar to other industrial enzymes, pectinases also face the constraint of thermo-tolerance and low yield in its economised production. The current review addresses the various strategies adopted to meet the high yield and thermo-tolerance of pectinases as well as the various attempts made in the field of pectinases to its improved production and better catalytic efficiency. The utilisation of natural as well as recombinant microbial sources, metagenomic approaches, metabolic engineering, site directed mutagenesis and media engineering techniques adopted in the field of pectinases have been discussed. The significance of pectinases in various industries is depicted by enlisting its applications. To the best our knowledge the current review is unique being the first attempt to compile the recent advancements in the field of pectinases. 相似文献
1000.
Impact of Cryopreservation on Caprine Fetal Adnexa Derived Stem Cells and Its Evaluation for Growth Kinetics,Phenotypic Characterization,and Wound Healing Potential in Xenogenic Rat Model 下载免费PDF全文