全文获取类型
收费全文 | 1383篇 |
免费 | 108篇 |
国内免费 | 5篇 |
出版年
2021年 | 25篇 |
2020年 | 21篇 |
2019年 | 17篇 |
2018年 | 36篇 |
2017年 | 33篇 |
2016年 | 44篇 |
2015年 | 64篇 |
2014年 | 69篇 |
2013年 | 95篇 |
2012年 | 101篇 |
2011年 | 85篇 |
2010年 | 54篇 |
2009年 | 39篇 |
2008年 | 58篇 |
2007年 | 55篇 |
2006年 | 46篇 |
2005年 | 44篇 |
2004年 | 29篇 |
2003年 | 29篇 |
2002年 | 34篇 |
2001年 | 30篇 |
2000年 | 30篇 |
1999年 | 21篇 |
1998年 | 20篇 |
1997年 | 9篇 |
1995年 | 10篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 16篇 |
1991年 | 24篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 19篇 |
1987年 | 30篇 |
1986年 | 21篇 |
1985年 | 26篇 |
1984年 | 17篇 |
1983年 | 12篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 13篇 |
1978年 | 9篇 |
1976年 | 8篇 |
1974年 | 10篇 |
1973年 | 14篇 |
1972年 | 8篇 |
1971年 | 8篇 |
1970年 | 10篇 |
1968年 | 8篇 |
排序方式: 共有1496条查询结果,搜索用时 93 毫秒
81.
82.
1. The myosin molecule from Ehrlich ascites tumour cells consists of heavy chains of about 200 kDa and three species of light chains of 20, 19 and 15 kDa. 2. The heavy chain can be phosphorylated in vitro either by endogenous Ca2+-independent kinase or by casein kinase II. 3. The 20 and 19 kDa light chains can be phosphorylated either by an endogenous kinase or by myosin light chain kinase from chicken gizzard. 4. The Ca2+-ATPase activity of the purified myosin was 0.3 mumol/min mg protein. The Mg2+-ATPase activity was activated 14-fold by actin upon the light chain phosphorylation. 相似文献
83.
84.
The growth of the very large CD8+ T cell clones in older mice is controlled by cytokines 总被引:3,自引:0,他引:3
Older humans and mice frequently contain very large clones of CD8(+) T cells. In mice these cells are phenotypically very similar to memory CD8(+) T cells. Like memory CD8(+) T cells, most members of the clones are in continuous slow division, apparently independently of Ag stimulation. Proliferation of the CD8(+) clonal T cells is inhibited in mice treated with Ab to the IL-2R beta-chain that blocks signaling by either IL-2 or IL-15. However, inhibition of IL-2 increases the numbers of dividing clonal cells. Therefore, like normal memory CD8(+) T cells, expansion of the clones is driven by IL-15 and inhibited by IL-2 and is probably limited by the amounts of IL-15 and IL-2 present in the host. Control by these two cytokines may account for the fact that, although the clones can be very large, they do not overwhelm or kill their hosts. Nevertheless the clonal cells compete successfully with normal memory CD8(+) T cells for growth. Perhaps the clonal cells use IL-15 more effectively or are more resistant to the inhibitory effects of IL-2. Thus they might affect the immune response of their hosts by competing for factors that stimulate and inhibit normal CD8(+) memory T cells. 相似文献
85.
A fatal cytokine-induced systemic inflammatory response reveals a critical role for NK cells 总被引:5,自引:0,他引:5
Carson WE Yu H Dierksheide J Pfeffer K Bouchard P Clark R Durbin J Baldwin AS Peschon J Johnson PR Ku G Baumann H Caligiuri MA 《Journal of immunology (Baltimore, Md. : 1950)》1999,162(8):4943-4951
The mechanism of cytokine-induced shock remains poorly understood. The combination of IL-2 and IL-12 has synergistic antitumor activity in vivo, yet has been associated with significant toxicity. We examined the effects of IL-2 plus IL-12 in a murine model and found that the daily, simultaneous administration of IL-2 and IL-12 resulted in shock and 100% mortality within 4 to 12 days depending on the strain employed. Mice treated with IL-2 plus IL-12 exhibited NK cell apoptosis, pulmonary edema, degenerative lesions of the gastrointestinal tract, and elevated serum levels of proinflammatory cytokines and acute phase reactants. The actions of TNF-alpha, IFN-gamma, macrophage-inflammatory protein-1alpha, IL-1, IL-1-converting enzyme, Fas, perforin, inducible nitric oxide synthase, and STAT1 did not contribute to the observed toxicity, nor did B or T cells. However, toxicity and death from treatment with IL-2 plus IL-12 could be completely abrogated by elimination of NK cells. These results suggest that the fatal systemic inflammatory response induced by this cytokine treatment is critically dependent upon NK cells, but does not appear to be mediated by the known effector molecules of this cellular compartment. These data may provide insight into the pathogenesis of cytokine-induced shock in humans. 相似文献
86.
Sap flow measurements with some thermodynamic methods,flow integration within trees and scaling up from sample trees to entire forest stands 总被引:19,自引:1,他引:18
Sap flow measurement techniques and evaluation of data are reviewed. Particular attention is paid to the trunk segment heat balance (THB) and heat field deformation (HFD) methods based on 30 years experience. Further elaboration of sap flow data is discussed in terms of integrating flow for whole stems from individual measuring points, considering variation of radial patterns in sapwood and variation around stems. Scaling up of data from sets of sample trees to entire forest stands based on widely available biometric data (partially on remote sensing images) is described and evaluated with a discussion of the magnitude of errors, the routine procedure applicable in any forest stand and practical examples. 相似文献
87.
Development and evaluation of a protein microarray chip for diagnosis of hepatitis C virus 总被引:3,自引:0,他引:3
A protein chip diagnostic kit was developed for the diagnosis of hepatitis C virus (HCV) based on the protein chip technique and the immuno-concentration method. This kit was designed for low-density protein chips and also for the availability of multiple sample screening. Applicability of the chip was evaluated using 96 blood specimens and the results were compared to results of an anti-HCV enzyme immunoassay (EIA) test. With further development, the technology associated with the development of this chip could be applied to the simultaneous detection of multiple protein-protein, protein-ligand interactions. 相似文献
88.
Nonlinear 3-D models with fluid-structure interactions (FSI) based on in vitro experiments are introduced and solved by ADINA to perform flow and stress/strain analysis for stenotic arteries with lipid cores. Navier-Stokes equations are used as the governing equations for the fluid. Hyperelastic Mooney-Rivlin models are used for both the arteries and lipid cores. Our results indicate that critical plaque stress/strain conditions are affected considerably by stenosis severity, eccentricity, lipid pool size, shape and position, plaque cap thickness, axial stretch, pressure, and fluid-structure interactions, and may be used for possible plaque rupture predictions. 相似文献
89.
Kim IJ Park JH Kang HC Shin Y Park HW Park HR Ku JL Lim SB Park JG 《Human genetics》2003,114(1):118-120
Recently, BRAF mutations were found in a variety of human cancers. Interestingly, the most common of BRAF mutation (V599E) has not been identified in tumors with K-ras mutations. Whereas the majority of human cancer types has been screened for BRAF mutations, no detailed studies on gastric cancers have been investigated. Thus, we decided to investigate the incidence of BRAF mutations in gastric cancers, and the relationship between BRAF and K-ras mutations in such cancers. Three non-pathogenic BRAF polymorphisms and seven K-ras missense mutations were found in 66 gastric cancers and 16 gastric cancer cell lines. Although only 9% of our gastric cancer panels had K-ras mutations, the incidence of BRAF mutations was not high. Thus, BRAF mutations, which are present in a variety of other human cancers, do not seem to be involved in gastric cancer development. 相似文献
90.
A synnematous species of Penicillium, P. calidicanium, is described and illustrated. The fungus was isolated from soil in Taiwan. Penicillium calidicanium can be placed in subgenus Biverticillium because of its symmetrical, biverticillate penicilli, ampulliform to acerose phialides, and ability to produce abundant synnemata in Czapek yeast extract agar, malt extract agar, and Czapek's solution agar. It is close to P. duclauxii and P. vulpinum, but differs in colony morphology, growth rate, morphology of the synnemata, and ornamentation of the conidial wall. 相似文献