全文获取类型
收费全文 | 1400篇 |
免费 | 5篇 |
国内免费 | 11篇 |
专业分类
系统科学 | 38篇 |
丛书文集 | 1篇 |
教育与普及 | 1篇 |
理论与方法论 | 13篇 |
现状及发展 | 256篇 |
研究方法 | 216篇 |
综合类 | 830篇 |
自然研究 | 61篇 |
出版年
2021年 | 4篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 15篇 |
2017年 | 18篇 |
2016年 | 7篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 19篇 |
2012年 | 100篇 |
2011年 | 190篇 |
2010年 | 37篇 |
2009年 | 9篇 |
2008年 | 103篇 |
2007年 | 103篇 |
2006年 | 98篇 |
2005年 | 121篇 |
2004年 | 94篇 |
2003年 | 74篇 |
2002年 | 88篇 |
2001年 | 21篇 |
2000年 | 16篇 |
1999年 | 8篇 |
1994年 | 3篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 11篇 |
1977年 | 14篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1974年 | 14篇 |
1973年 | 7篇 |
1972年 | 8篇 |
1971年 | 12篇 |
1970年 | 16篇 |
1969年 | 18篇 |
1968年 | 13篇 |
1967年 | 11篇 |
1966年 | 11篇 |
1965年 | 7篇 |
排序方式: 共有1416条查询结果,搜索用时 0 毫秒
41.
42.
Thomas A. Knetsch 《Journal of forecasting》2007,26(7):527-549
The paper develops an oil price forecasting technique which is based on the present value model of rational commodity pricing. The approach suggests shifting the forecasting problem to the marginal convenience yield, which can be derived from the cost‐of‐carry relationship. In a recursive out‐of‐sample analysis, forecast accuracy at horizons within one year is checked by the root mean squared error as well as the mean error and the frequency of a correct direction‐of‐change prediction. For all criteria employed, the proposed forecasting tool outperforms the approach of using futures prices as direct predictors of future spot prices. Vis‐à‐vis the random‐walk model, it does not significantly improve forecast accuracy but provides valuable statements on the direction of change. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
43.
Summary Lanthanum had a small effect on the barrier, but did not significantly increase its sodium or patossium permeability. There was no effect on nerve conduction unless the barrier was deliberately damaged. The results lend confidence to the use of lanthanum as an extracellular tracer. 相似文献
44.
R. S. Verma S. Thomas M. Coleman R. T. Silver H. Dosik 《Cellular and molecular life sciences : CMLS》1986,42(4):440-441
Summary A random distribution of the Y-chromosome at somatic metaphase was found in 50 patients with Ph' positive chronic myelogenous leukemia (CML). Thus, it is concluded that the positive of the Y-chromosome at somatic metaphase does not appear to influence the loss from bone marrow cells. 相似文献
45.
46.
47.
48.
Garcia-Gonzalo FR Corbit KC Sirerol-Piquer MS Ramaswami G Otto EA Noriega TR Seol AD Robinson JF Bennett CL Josifova DJ García-Verdugo JM Katsanis N Hildebrandt F Reiter JF 《Nature genetics》2011,43(8):776-784
Mutations affecting ciliary components cause ciliopathies. As described here, we investigated Tectonic1 (Tctn1), a regulator of mouse Hedgehog signaling, and found that it is essential for ciliogenesis in some, but not all, tissues. Cell types that do not require Tctn1 for ciliogenesis require it to localize select membrane-associated proteins to the cilium, including Arl13b, AC3, Smoothened and Pkd2. Tctn1 forms a complex with multiple ciliopathy proteins associated with Meckel and Joubert syndromes, including Mks1, Tmem216, Tmem67, Cep290, B9d1, Tctn2 and Cc2d2a. Components of this complex co-localize at the transition zone, a region between the basal body and ciliary axoneme. Like Tctn1, loss of Tctn2, Tmem67 or Cc2d2a causes tissue-specific defects in ciliogenesis and ciliary membrane composition. Consistent with a shared function for complex components, we identified a mutation in TCTN1 that causes Joubert syndrome. Thus, a transition zone complex of Meckel and Joubert syndrome proteins regulates ciliary assembly and trafficking, suggesting that transition zone dysfunction is the cause of these ciliopathies. 相似文献
49.
Dobbins SE Broderick P Melin B Feychting M Johansen C Andersson U Brännström T Schramm J Olver B Lloyd A Ma YP Hosking FJ Lönn S Ahlbom A Henriksson R Schoemaker MJ Hepworth SJ Hoffmann P Mühleisen TW Nöthen MM Moebus S Eisele L Kosteljanetz M Muir K Swerdlow A Simon M Houlston RS 《Nature genetics》2011,43(9):825-827
To identify susceptibility loci for meningioma, we conducted a genome-wide association study of 859 affected individuals (cases) and 704 controls with validation in two independent sample sets totaling 774 cases and 1,764 controls. We identified a new susceptibility locus for meningioma at 10p12.31 (MLLT10, rs11012732, odds ratio = 1.46, P(combined) = 1.88 × 10(-14)). This finding advances our understanding of the genetic basis of meningioma development. 相似文献
50.