全文获取类型
收费全文 | 1376197篇 |
免费 | 122925篇 |
国内免费 | 1435篇 |
专业分类
1500557篇 |
出版年
2021年 | 17886篇 |
2019年 | 16142篇 |
2018年 | 18041篇 |
2017年 | 16812篇 |
2016年 | 28215篇 |
2015年 | 42322篇 |
2014年 | 50315篇 |
2013年 | 76446篇 |
2012年 | 37796篇 |
2011年 | 26925篇 |
2010年 | 44096篇 |
2009年 | 45281篇 |
2008年 | 25767篇 |
2007年 | 23865篇 |
2006年 | 28713篇 |
2005年 | 29755篇 |
2004年 | 29031篇 |
2003年 | 26342篇 |
2002年 | 24476篇 |
2001年 | 33444篇 |
2000年 | 30872篇 |
1999年 | 31055篇 |
1998年 | 25409篇 |
1997年 | 25318篇 |
1996年 | 24773篇 |
1995年 | 22935篇 |
1994年 | 22723篇 |
1993年 | 21817篇 |
1992年 | 27263篇 |
1991年 | 25817篇 |
1990年 | 24550篇 |
1989年 | 25252篇 |
1988年 | 23475篇 |
1987年 | 22371篇 |
1986年 | 21216篇 |
1985年 | 23087篇 |
1984年 | 22854篇 |
1983年 | 20233篇 |
1982年 | 20599篇 |
1981年 | 19832篇 |
1980年 | 18592篇 |
1979年 | 19046篇 |
1978年 | 17900篇 |
1977年 | 17200篇 |
1976年 | 16473篇 |
1975年 | 16011篇 |
1974年 | 16670篇 |
1973年 | 16990篇 |
1972年 | 14582篇 |
1971年 | 13363篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
E. N. Medvedeva N. A. Neverova T. E. Fedorova V. A. Babkin E. S. Meteleva A. V. Dushkin T. G. Tolstikova M. V. Khvostov M. P. Dolgikh 《Russian Journal of Bioorganic Chemistry》2010,36(7):853-859
It has been found by gel-penetrating chromatography and quantitative 13C NMR spectroscopy that mechanochemical processing of arabinogalactan isolated from the wood of the Siberian larch changes
the molecular mass distribution, monosaccharide composition, and the degree of branching of its macromolecules. This is due
to the partial destruction of polysaccharide macromolecules and subsequent recombination of resulting fragments. The intensity
of these processes depends on the conditions of mechanochemical processing. Based on the data of IR and 13C NMR spectra, the conclusion has been drawn that no functionalization of arabinogalactan macromolecules occurs under these
conditions. The toxicopharmacological properties of mechanically processed arabinogalactan have been studied. Its acute toxicity
is >5000 mg/kg. 相似文献
132.
133.
134.
Protein metal-binding sites. 总被引:2,自引:0,他引:2
Metal ions have a role in a variety of important functions in proteins including protein folding, assembly, stability, conformational change, and catalysis. The presence or absence of a given metal ion is crucial to the conformation or activity of over one third of all proteins. Recent developments have been made in the understanding and design of metal-binding sites in proteins, an important and rapidly advancing area of protein engineering. 相似文献
135.
V K Khugaeva E D Klimenko P N Aleksandrov G F Leskova M I Reutov 《Biulleten' eksperimental'no? biologii i meditsiny》1985,100(7):15-19
Experiments were made on rabbit fed an atherogenic diet (0.5 g/kg cholesterol) singly for 15 and 24 h and repeatedly for 3, 9 and 30 days. At early stages of lipid metabolism distress the interrelationship was established between blood rheological disorders and microcirculatory abnormalities. The dependence of the initial reaction of some rheological characteristics on their initial level was marked. 相似文献
136.
Vernon Shattuck Frank R. Katterman 《Biochemical and biophysical research communications》1982,109(3):1017-1025
When cotyledonary tissue of cotton are treated with the mutagen ethyl methanesulfonate and then germinated, an enhanced, unscheduled DNA synthesis response is observed, along with a concomitant increase in the thymidine triphosphate precursor pool size. The implications of these results are discussed in this paper. 相似文献
137.
138.
139.
140.
Nitrogen fertigation of greenhouse-grown cucumber 总被引:2,自引:0,他引:2
I. Papadopoulos 《Plant and Soil》1986,93(1):87-93
Summary This greenhouse study investigated the response of trickle-irrigated cucumber (Cucumis sativa cv. ‘Petita’) to three N levels applied with every irrigation via the irrigation stream. The plants were grown in pots filled
with 12 kg of soil. Water containing 5.8, 11.8, or 17.8 mmol N/l, and uniformly supplied with 2.0 and 3.9 mmol/l of P and
K, respectively, was applied two to three times daily. In all treatments of 0.3 leaching fraction was allowed.
The resulting total N applications were 15.7, 31., and 47.2 g N/plant. The total amount of water applied was 1851/plant. Total
N and NO3-N, in lajinae and petioles, increased with increasing N level whereas P and K in generated decreased. Although different
NO3/NH4 ratios in the treatments may have influeced the response to N, it could be concluded that the highest yield was obtained
with 11.8 mmol N/1 due to increased number of fruit. In the root volume of this treatment the NO3-N concentration in the soil solution was aroun 7 mmol/1 for most of the growing season. The dry matter concentration of fruits
was not affected by the N levels.
It was concluded that 11.8 mmol N/1 applied with every irrigation via the irrigation stream is adequate to cover the needs
of greenhous-grown cucumber for higher yield (9.42 kg/plant over a harvesting period of 93 days). 相似文献