全文获取类型
收费全文 | 1567篇 |
免费 | 519篇 |
国内免费 | 26篇 |
出版年
2024年 | 13篇 |
2023年 | 78篇 |
2022年 | 66篇 |
2021年 | 104篇 |
2020年 | 87篇 |
2019年 | 102篇 |
2018年 | 117篇 |
2017年 | 113篇 |
2016年 | 140篇 |
2015年 | 146篇 |
2014年 | 229篇 |
2013年 | 161篇 |
2012年 | 72篇 |
2011年 | 126篇 |
2010年 | 45篇 |
2009年 | 44篇 |
2008年 | 48篇 |
2007年 | 55篇 |
2006年 | 43篇 |
2005年 | 37篇 |
2004年 | 18篇 |
2003年 | 26篇 |
2002年 | 18篇 |
2001年 | 17篇 |
2000年 | 17篇 |
1999年 | 24篇 |
1998年 | 4篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1973年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有2112条查询结果,搜索用时 140 毫秒
1.
Sequential medical trials involving paired data 总被引:2,自引:0,他引:2
2.
Benjamin C. Blum Weiwei Lin Matthew L. Lawton Qian Liu Julian Kwan Isabella Turcinovic Ryan Hekman Pingzhao Hu Andrew Emili 《Molecular & cellular proteomics : MCP》2022,21(1):100189
Metabolism is recognized as an important driver of cancer progression and other complex diseases, but global metabolite profiling remains a challenge. Protein expression profiling is often a poor proxy since existing pathway enrichment models provide an incomplete mapping between the proteome and metabolism. To overcome these gaps, we introduce multiomic metabolic enrichment network analysis (MOMENTA), an integrative multiomic data analysis framework for more accurately deducing metabolic pathway changes from proteomics data alone in a gene set analysis context by leveraging protein interaction networks to extend annotated metabolic models. We apply MOMENTA to proteomic data from diverse cancer cell lines and human tumors to demonstrate its utility at revealing variation in metabolic pathway activity across cancer types, which we verify using independent metabolomics measurements. The novel metabolic networks we uncover in breast cancer and other tumors are linked to clinical outcomes, underscoring the pathophysiological relevance of the findings. 相似文献
3.
4.
5.
《Fungal biology》2020,124(2):83-90
Latterly, the upsurge in use of antifungal drugs has brought about the emergence of several drug-resistance strains, making it skeptical to continue relying on current therapeutic regime. In the necessity of resistance-free antifungal agent, flavonoids presented possibilities of replacing existing drugs, displaying antifungal activity against pathogenic fungi. Among them, quercetin, one of the most representative flavonoids, exhibited antifungal activity against Candida albicans. To inspect the further understanding regarding quercetin, the antifungal mode of action of quercetin was investigated. In the initial step, the apoptosis was monitored after quercetin treatment. Moreover, intracellular levels of Mg2+ was assessed and was determined that Mg2+ increase occurred under the influence of quercetin. In addition, several features of mitochondrial dysfunction were monitored. Mitochondrial dysfunction triggers decrease in mitochondrial redox levels and leads to disruption in mitochondrial antioxidant system. Increased intracellular ROS and decreased intracellular redox levels were also displayed, indicating the occurrence of overall disruption in antioxidant systems. Sequentially, DNA fragmentation was observed and this DNA damage in turn induces apoptosis. In analyses, hexaamminecobalt(III) chloride (Cohex) was applied to inhibit Mg2+ transport between cytosol and mitochondria. Cohex attenuated the effects induced by quercetin, which demonstrates that the presence of Mg2+ is essential in quercetin-induced apoptosis. 相似文献
6.
Berthold Lausen Torsten Hothorn Frank Bretz Martin Schumacher 《Biometrical journal. Biometrische Zeitschrift》2004,46(3):364-374
The identification and assessment of prognostic factors is one of the major tasks in clinical research. The assessment of one single prognostic factor can be done by recently established methods for using optimal cutpoints. Here, we suggest a method to consider an optimal selected prognostic factor from a set of prognostic factors of interest. This can be viewed as a variable selection method and is the underlying decision problem at each node of various tree building algorithms. We propose to use maximally selected statistics where the selection is defined over the set of prognostic factors and over all cutpoints in each prognostic factor. We demonstrate that it is feasible to compute the approximate null distribution. We illustrate the new variable selection test with data of the German Breast Cancer Study Group and of a small study on patients with diffuse large B‐cell lymphoma. Using the null distribution for a p‐value adjusted regression trees algorithm, we adjust for the number of variables analysed at each node as well. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
Gas exchange studies in two Portuguese grapevine cultivars 总被引:8,自引:0,他引:8
M. Manuela Chaves Peter C. Harley John D. Tenhunen Otto L. Lange 《Physiologia plantarum》1987,70(4):639-647
Gas exchange characteristics of leaves of Vitis vinifera L. cvs Tinta Amarela and Periquita, two grapevine cultivars grown in distinct climatic regions of Portugal, were studied under natural and controlled conditions. Daily time courses of gas exchange were measured on both a hot, sunny day and a cooler, partly cloudy day. Responses of net photosynthesis to irradiance and internal partial pressure of CO2 , were also obtained. A strong correlation between net photosynthesis (PN ) and leaf conductance (gs ) was found during the diurnal time courses of gas exchange, as well as a relatively constant internal partial pressure of CO2 (Pi ), even under non-steady-state conditions. On the cloudless day, both PN and gs were lower in the afternoon than in the morning, despite similar conditions of leaf temperature, air to leaf water vapor deficit and irradiance. The response curves of net photosynthesis to internal CO2 showed linearity up to pi values of 50 Pa, possibly indicating a substantial excess of photosynthetic capacity. When measured at low partial pressures of O2 (1 kPa), PN became inhibited at high CO2 levels. Inhibition of PN at high CO2 was absent under normal levels of O2 (21 kPa). Significant differences in gas exchange characteristics were found between the two cultivars, with T. Amarela having higher rates under similar measurement conditions. In particular, the superior performance of T. Amarela at high temperatures may represent adaptation to the warmer conditions at its place of origin. 相似文献
8.
Almond plants (Amygdalus communis L.) of the Garrigues variety were grown in the field drip irrigated and rainfed. Leaf water potential (Ψ) and leaf conductance
(g1) were determined throughout one growing season. Pre-dawn measurement for Ψ in the irrigated treatment was consistent through
the growing season, whereas in the rainfed treatment it decreased gradually. Ψ values at midday (Ψ minimum) was closely dependent
on atmospheric evaporative demand, and their recovery was quicker in the wet treatment than in the dry. The g1 values were higher in the wet than dry treatments, decreasing in both cases by leaf ageing. Maximum values for g1 were reached when evaporative demand was highest in the day. The relationship between Ψ and g1 revealed a decrease in the hysteresis throughout the growing season, being most marked in the dry treatment. The results
highlight the close dependence of Ψ and g1 on evaporative demand, leaf ageing and irrigtion treatment during the growing season. 相似文献
9.
Using [3H] diazepam as ligand, it is possible to distinguish neuronal binding sites from those present on glial elements and in peripheral tissues (non-neuronal). The function of the "non-neuronal" binding sites is still obscure. Preliminary data showed a distribution of [3H] diazepam binding sites in kidney that could suggest a localization along the renal tubules. This is the site at which a renal peptide, arginine-vasopressin (AVP) is supposed to act. In an attempt to examine the function of these "non-neuronal" sites, we studied the [3H] diazepam binding in kidney of Brattleboro rats which lack AVP and present the symptoms of diabetes insipidus. The homozygous Brattleboro rats showed an increase in the apparent number of benzodiazepine binding sites (Bmax) compared to Long-Evans control rats. Replacement of AVP in these animals results in a reversal of the electrolyte alterations of diabetes insipidus and in an increase of the affinity of the [3H] diazepam binding. These findings may indicate a possible relationship between benzodiazepine binding sites and vasopressin action in kidney and may support receptor function of these "non-neuronal" binding sites. 相似文献
10.
Microfluorometric detection of asymmetry in the centromeric region of mouse chromosomes 总被引:2,自引:0,他引:2
A lateral asymmetry in the centromeric region of mouse chromosomes is revealed in studies involving the BUdR quenching of 33258 Hoechst fluorescence. This cytologically detected asymmetry may reflect the unequal distribution of thymidine between the two chains of mouse satellite DNA. 相似文献